Department of “Optical Instruments for Scientific Research” (RL 3)

Rodionov E.M.

Technological basis for the design of elements and functional devices of optical instruments

Part I. Parts Design Basics

Tutorial

1. Introduction

When creating new devices, they perform work called designing and (or) constructing the product.

In practice and in the literature, there are two points of view regarding the essence of these terms. In some sources, the entire process of developing a new product is often called design.

In the literature these concepts are distinguished. It is believed that design precedes construction and consists of identifying the needs of society for a product, searching for ideas, physical effects, expedient methods and principles of operation, and synthesizing the functional structures of possible options.

Design is understood as the development of a specific version of a product based on the design results, during which its design is created: device, composition, mutual arrangement parts and elements, the method of their connection and interaction, taking into account manufacturing technology, etc.

It should be noted that, despite the difference between the concepts of design and construction, it is impossible to find a clear boundary between these design and engineering procedures.

Modern optical devices are increasingly subject to increased requirements for quality indicators, which are laid down already at the design and construction stage. With the complication of design objects, the work of the designer becomes more and more complex and responsible, and the development of the scientific basis for design becomes increasingly important. In recent years, this development has been uneven. Along with the existing powerful apparatus of engineering verification calculations, there are still very few methods of design calculations necessary for the synthesis and optimization of design solutions, and in real design empirical and heuristic methods predominate.

Characteristic features of the design of complex objects are the mass nature of the tasks being solved and the multivariability possible solutions. Two groups of methods should be distinguished: search method optimal solutions and methods for assessing possible solutions: the decision-making process is based on the synthesis of both.

The main search method at present is the analogy method, due to the personal experience of the designer and experience generalized in reference literature: most decisions are made by this method. The assessment of decisions made is qualitative in nature and only in some cases is based on performing test calculations (for strength, rigidity, accuracy).

In cases where difficulties arise in making an unambiguous decision, the designer resorts to the method of enumerating known options. The assessment of options is of great importance and in particularly complex cases is based on verification calculations and even experimental studies, but even then the decision is made on the basis of experience. The main reason for this is due to the current lack of engineering methods for performing assessments based on a large number of criteria.

The next stage of complication of the decision-making process is characterized by the insufficiency of the set of known possible options; the design process begins with the search for suitable options, which is carried out by trial and error, and consists of developing new options based on a combination of known ones.

Experience shows that the described design methods do not ensure optimal decisions under these conditions. The main reason is the difficulty of simultaneous optimization of object parameters for all indicators. In real design conditions, the designer, although he keeps all the indicators in his field of attention, gives preference only to some, in his opinion, the most critical in this case.

Thus, there is currently only limited optimization in design creation. The development of the theoretical foundations of design at the level of synthesis occurs slowly. Therefore, it is necessary, first of all, to develop principles that establish dependencies between design solutions and quality indicators of constructed objects. Only a few works of this kind are known. The main literature on design issues is of a prescription nature, teaches design through examples and does not contain theoretical generalizations.

Particularly noteworthy is the role of accuracy theory in the design of instruments. The fundamentals of the theory of accuracy are formulated in the works and continued in the works. Against their background, the lag in design issues is even more clearly visible.

In this regard, improving the device design process is of great importance.

It is known that parts as an object of design are the primary elements of any real structure. The design of parts is the most widespread operation in general process device design. However, very little attention is paid to the design of parts in the literature and production practice. There are scattered recommendations for the design of parts taking into account strength and rigidity that are not related to operating conditions and especially to manufacturing and assembly technology.

This tutorial focuses on the technological aspect of design. At the Moscow Higher Technical University, at the instrument-making faculty, for more than 40 years there was a course “Instrument Engineering Technology” with a single name for all departments from optics to computers. A course that was not associated with the design of specific devices. See, for example, the textbook “Instrument Making Technology” 1968 - a general educational manual on processes: casting, stamping, plastics, cutting, etc.

Although for a long time there was a rule at enterprises abroad: “The product must be designed for the technological process.”

There is no technology at all, just like there is no product without technology. Each product, each detail requires its own technology. For example, there may be one process: stamping for computer parts and stamping for iris diaphragms, but manufacturing technologiesdifferent . There are known unsuccessful attempts to produce copied products in the country. You can make drawings, even convert inches to mm, but, alas, the technology cannot be copied.

It is now a mistake to divide diploma projects into parts: “Design part”, “Technological part”, etc. . It is not divided into parts, it is one whole!!

The manual was written on the basis of lectures given by the author to students of departments RL2 and RL3, and also used books by V.V. Kulagina, S.M. Latyeva, S.T. Zuckerman - famous designers of precision mechanisms and instruments.

The textbook is devoted to the basics of designing modern precision instruments, typical representatives of which are optical instruments containing mechanical, electronic and optical functional devices and elements. The specificity of the design of such devices is that their quality indicators, and first of all indicators of accuracy, manufacturability and reliability, largely depend on the implementation of certain methods, rules and principles of design, methods and methods of parametric and precision synthesis of structures, knowledge of ways and principles for increasing quality targets in design. The textbook is intended for students, undergraduates, graduate students and teachers of higher educational institutions of instrument engineering, as well as engineering and technical workers in industry.

The file will be sent to selected email address. It may take up to 1-5 minutes before you received it.

The file will be sent to your Kindle account. It may take up to 1-5 minutes before you received it.
Please note you"ve to add our email [email protected] to approved e-mail addresses. Read more.

You can write a book review and share your experiences. Other readers will always be interested in your opinion of the books you"ve read. Whether you"ve loved the book or not, if you give your honest and detailed thoughts then people will find new books that are right for them.

TEACHING MANUAL FOR UNIVERSITIES m p. M. Latyev DESIGN OF PRECISION (OPTICAL) INSTRUMENTS [ Lь ] POAYLTECHNIKA "11 PUBLISHING HOUSE St. Petersburg 2007 UDC 681.7 VVK 22.34 L27 The publication was published with the support of: Committee on Printing and Interaction with Mass Media St. Petersburg Latyev S. M . L27 Design of precision (optical) instruments: Textbook. St. Petersburg: Politekhnika, 2007. 579 p.: ill. containing mechanical, electronic, and optical components functional devices and elements. Spezi<})и:ка конструирования таких приборов закл]очается в том, что их показатели:качества, и в первую очередь показатели точности, технолоrич ности и надежности, в существенной степени зависят от выполнения опреде лепных методов, правил и принципов I\онструирования, способов и методов параметричеСhоrо и точностноrо синтеза конструкций, знаний путей и при емов повышения целевых показателей каче(тва при проеhтировании. Учебное п()собие предназначено для студентов, маrиетрантов, аспиран ТОВ и преподавателей высших учебных заведений приборостроительноrо про ilya, and also engineering and technical work in the industry. UDC 681.7 BBK 22.34 ISBN 5 7325..0563..6 @ Politekhnika Publishing House, 2007 Preface The creation of new technology, based on the results of fundamental and applied research, contains a special ethos of mental activity, which consists in developing a technical project for a future product. The objectives of this stage are: identifying the need of society for a particular technical product (taking into account technical and economic characteristics, consumption of natural resources, impact on the environment, etc.); search for ideas and methods of engineering solutions; development of a specific product design with the release of the necessary technical documentation. This work is called design and (or) KOH design of the product. Design and construction are interconnected, complement others, are carried out, as a rule, by specialists of the same profession...............design engineers, have the same ultimate goal of developing HOBOR from the product, and therefore The entire process is often called design or construction. However, in practice and in the literature there is another point of view, according to which these concepts are distinguished. It is believed that design precedes construction and consists in identifying the needs of society for a product, in searching for ideas, (l)physical effects, expedient methods and principles of action, in synthesizing (l)functional structures of possible options. By design we mean the development of KOHKpeTHO ro option products based on the design results, in which an ero design is created: structure, composition, relative arrangement of parts and elements, the method of their connection and interaction, taking into account the materials used, manufacturing technology, etc. During the design process, drawings of assembly units and parts are produced , diagrams, calculate tolerances for accuracy and technology for manufacturing and assembling parts, establish technical specifications for the device, draw up a technical description, develop other KOHCTPYKTOP documentation necessary for the manufacture and operation of the product 3 There are two opinions about the intersubordination of the concepts of design and construction. According to one of them, design is an iterative process of transforming information in order to obtain technical systems that satisfy certain human needs, and design is part of design, which consists of transforming information in order to obtain analytical models of technical systems. According to another opinion, design includes ... design (and not vice versa, as in the first case), since under the designer comes the construction, creation of a technical object, and under the designer only the development of the concept, the search for ideas, foresight, etc. It should be noted that, despite the existing differences between the concepts of design and construction, it is not possible to find a clear boundary between these procedures of design and construction activities. At the stage of design work, there are elements of design (for example, development. layouts to test the physical principles of operation, selection and calculation of some parts of the system), and at the design stage one cannot do without design procedures (search for options for used functional devices, structures, development and refinement of circuits, theoretical and experimental research of the .. characteristics of some engineering solutions). This textbook is devoted to the basics of designing precision instruments, typical representatives of which are currently optical instruments containing mechanical, electronic and optical q)functional devices and elements. The specificity of the design of such devices lies in the fact that their quality indicators, and first of all accuracy, reliability and manufacturability, depend to a significant extent on the implementation of certain rules and principles of design, methods and methods of c) , parametric and accuracy synthesis of structures, knowledge of ways to improve the quality of devices during design. Despite the fact that the issues under consideration are illustrated primarily on the designs of optical instruments, they fully apply to the design of other types of precision instruments and machines. Currently, enough MHoro publications on design and engineering activities are known. At the same time, 4 it should be noted that on applied issues of KOH design work in the field of optical instrumentation there is literature HeMHoro. The most accessible are the handbook for the designer of optical-mechanical devices, textbooks and teaching aids on the design of optical and optical-electronic devices. It is naturally impossible to consider all the theoretical and practical aspects of the design of optical instruments in one book, even taking into account the fact that students and other readers are already familiar with such necessary fundamentals and sections of the design of devices and machines as “Tolerances and fits. , “Strength of materials.”, “Device parts.”, “Materials science and technology of KOH structural materials,” “Theory of machines and mechanisms,” “Theoretical mechanics,” “Optical technology,” “Applied optics. etc. Therefore, the author, relying on the material presented in the above-mentioned textbooks and teaching aids, tried to develop and supplement it with consideration of those design issues that are mainly related to the accuracy indicators of devices and their elements. The tutorial consists of four parts. The first part discusses general issues and principles of design of precision instruments and their elements. The second part is devoted to the synthesis and analysis of the accuracy of instruments, concepts and methods for achieving their reliability. The third part studies methods for increasing and ensuring the “quality of devices during design. Practical aspects of the design” of elements of optical devices are reflected in the fourth part. The manual is written on the basis of an academic discipline read by the author to students of optical specialties of St. Petersburg State University of Information Technologies, Mechanics and QPtics (ITMO), taught at the university more than 50 years ago by famous designers of precision mechanisms and instruments S. T. Tsukkerman and V. V. Kularin, whose books contained the theoretical and practical foundations of the design training of students in the field of precision instrument making in the past. The author expresses gratitude and gratitude to the associate professor of the department “Computerization and design of optical instruments.” ITMO and. N. Timoshchuk I r. V. EuropoBY for providing materials and assistance in preparing the MANUAL. 5 Part 1 principles of the DESIGN of precision INSTRUMENTS AND THEIR ELEMENTS Introduction There are a huge number of different types and types of precision instruments. For example, only optical devices are classified into rheodesic, spectral, measuring, military, space, q), video, control, adjustment, telecommunication, medical, etc. The range of such devices reaches several thousand items. The nomenclature of industrially launched functional devices and elements used in precision instrument making reaches several tens of thousands of items. The designer, when designing this technique, must take into account the specifics of the specific design object. However, the training of specialists in design and engineering activities cannot and should not be of a recipe nature and be based on studying the specifics of creating a Toro or other KOHKPETHoro product or a similar class of product. Therefore, it seems unjustified to train designers, for example, only in theoredic instruments, or in microscopy, or in gyroscopic techniques. It is necessary to study the methods, general rules and principles of design and construction that are used to create both all technical products and their various types and classes, united by common target characteristics. This will make it possible to train designers of mi and pOKoro profiles, who will later be able to master the specialty of designing specific types of products “on the job.” Design and construction methods describe possible ways and means of searching for ideas and engineering solutions to design problems (which, as a rule, do not depend on the type of equipment being created). General design rules are understood as recommendations for solving certain design problems to meet the requirements for both o all technical products (for example, their unification, recycling), and for solving a number of problems defined the type of technology being created (for example, its layout, structure). Design principles are those rules and design decisions that make it possible to ACHIEVE the required target functions of a product (main indicators of product quality). For all precision instruments, such quality indicators are indicators of accuracy, quality and technicality, therefore, this part of the textbook mainly outlines the design principles that influence these indicators. Less attention is paid to methods and general rules of design and construction, since they are discussed in numerous literature on device design and the fundamentals of technical creativity. Chapter 1 PRINCIPLES OF DESIGN OF ELEMENTS AND FUNCTIONAL DEVICES OF OPTICAL DEVICES 1.1. GENERAL PRINCIPLES OF DESIGN OF OPTICAL INSTRUMENTS 1.1.1. STAGES OF DESIGN DESIGN WORK According to ROCT 2.103 68 stages of design work and stages of development of design DOKY Technical specification Technical proposal "OHsp py". 1.1. Stages of the third "Pl, but" construction" work 7 mentation are performed in the sequence shown in Fig. 1.1. Let us briefly consider the contents of the stages and the set of developed design documentation (CD) in relation to optical devices (OD). A technical specification (TOR) is a document, with KOToporo the development of any OP begins, establishing its intended purpose, scope of application, technical and technical-economic quality indicators, composition, operating conditions and modes, stages and timing of work. The technical specification is drawn up by the customer organization with possible participation and coordination with the contractor organization. The main requirements for the technical specification are set out in ROCT 15.001 73. The technical proposal is a set of design documents developed in order to identify possible options for technical solutions and clarify the technical specifications, which contains: technical and feasibility studies of the feasibility of developing OP documentation based on an analysis of technical specifications and various options for possible solutions; comparative assessment of solutions taking into account the design and operational features of the developed and similar existing OPs, as well as trends and prospects for their development; results of checking options for patentability, patent purity and competitiveness; preliminary assessment of the technological effectiveness of design options, their compliance with the requirements of standardization, unification, safety, etc. At this stage, calculations are performed to confirm the performance of Toro or another solution. Some solutions are verified through experimental studies on mock-ups. The design documentation issued at this stage contains (l)functional diagrams of possible OP solutions, simplified general drawings, a statement of technical proposal, a patent form, and an explanatory note. The scope of work at this stage is reflected in ROCT 2.118 73. Draft design is a set of design documentation developed in order to obtain fundamental design solutions for the selected option of the design. It gives a general idea of ​​the operating principle and structure of the device, as well as its main characteristics. At this stage, all necessary OP calculations are performed: parametric, optical, CBeTOTexical, accuracy, etc. 8 The produced CD contains: basic OP circuits (optical<> , kinematic, electrical); general view drawings (with possible simplifications) and the most important assembly units, giving an idea of ​​the layout of the device and the interaction of its parts; an explanatory note with the results of calculations, information about the technical and economic characteristics of the project, additional results of patent research, etc. The scope of work at this stage is reflected in ROCT 2.119 73. Technical project is a set of design documentation that contains the final technical solution that gives a complete understanding of the design of the device. At this stage: a more detailed development of the design of the device and its components is carried out; schematic diagrams and connection diagrams are developed; the dimensional, installation and connection dimensions are coordinated; technological equipment is determined; the necessary equipment is developed; decisions are made on the selection of control equipment, installation, storage and transportation of equipment. Issued design documents: general design drawings and assembly units, dimensional drawings, drawings of all diagrams, list of... purchased products, patent form, explanatory note, etc. The scope of work at this stage is reflected in ROCT 2.120 73. The worker produces a complete set of design documentation for the manufacture and operation of the op. At this stage: drawings of all details of the device design are made; develop requirements and methods for assembly, adjustment and testing; ... compile a technical description and operating instructions for the device, an ero form and a technical passport (it contains information about the characteristics of the OP, the results of ero testing, the composition of the kit, warranties, etc.); develop technological processes for manufacturing complex and critical parts; draw up technical specifications that contain requirements that are not in the drawings, but necessary for the manufacture and debugging of the equipment; make up statements of purchased products, grades and ranges of materials, spare tools, accessories, etc. In charge. In cases, in order to identify possible errors in the working drawings of parts, so-called “control assemblies” are produced, assembly drawings of the Bcero device 9 or ero main components, which are made according to specific dimensions read from the working drawings of the mating parts. After preparation and approval, the design work proceeds to this. production, testing and testing of the designed device. In the case where not a single, but serial production is planned, a prototype or a pilot batch of devices is manufactured. Comprehensive tests of manufactured samples make it possible to draw a conclusion about the compliance of the device with the specifications, identify possible design flaws and eliminate them by adjusting or finalizing the design documentation. It should be noted that not all of the listed stages are required to be carried out as independent ones; for example, a preliminary design can be excluded, or technical and detailed designs can be combined. A more detailed list of work performed at various stages of design is presented in the corresponding rOCTax and in the work. 1.1.2. QUALITY INDICATORS PROVIDED IN THE DESIGN OF OPTICAL DEVICES At all stages of design of an optical device, the designer must find technical solutions that ensure that the device being created meets the requirements not only of the technical specifications, but also of requirements not reflected in the technical specifications, but the implementation of which is necessary in any technical project. We are talking about requirements that ensure the creation of a high-quality device or any other design object. In accordance with ROCT 22851 77, ROCT 15467 79, the quality of a device (product) is the set of properties of the device that determine its suitability to meet certain needs in accordance with its intended purpose. To objectively assess the quality of a device, its properties are characterized quantitatively by quality indicators. Quality indicators characterize the technical and economic features of the device and are classified into the following main groups. Design indicators characterize the purpose, scope, performance; accuracy, light intensity, resolving power, range , overall dimensions, weight, etc. 10 This is the most numerous group of product quality indicators. For OP, there are both general indicators for ... values ​​(indicators of operating accuracy, image quality created by optical systems) and specific ones (indicators). , characterizing the parallelism of the sighting axes of binocular devices, the magnification of microscopes, the aperture ratio of photographic devices, the radiation power of laser devices, etc.). INDICATOR RELIABILITY is characterized by reliability (the property of the device to remain operational during HeKoToporo time or operating time without forced breaks), durability (the property of the device for long-term operation with the necessary breaks for technical maintenance and repairs), peM01ltOppUZOa1l0Cmb (the adaptability of the device to prevent, detect and eliminate failures through maintenance and repairs) and storability (the property of the device cp to store specified indicators during and after the period of storage and transportation). Indicators of technological quality characterize the compliance of the device and its elements with the optimal conditions of modern production. The most important technological indicators of the quality of the device are, for example, - the coefficient of assembly (BLOCKIl0st), the coefficient of use of rational materials, specific labor intensity. by a person from the point of view of work convenience, safety, occupational safety. Erronomic indicators are divided into physical (noise level, amplitude and frequency of vibration, radiation level, temperature, degree of contamination, toxicity, etc.), anthropometric (size and location). screens, indicators, handles, eyepieces, headbands, seats, etc.), psychophysical (ranges of forces on the handles, speed of movements, level of illumination, color and brightness of light signals, timbre and strength of sound signals, etc.) etc.), psychological (volume and intensity of information flow, number and frequency of operations performed, number and location of control, signal, controlled elements, etc.). Aesthetic indicators characterize the appearance of the device, its compliance with modern style, the harmonious combination of individual elements of the device with each other, the compliance of the design of the device with its intended purpose, the quality and perfection of external finishing elements, surfaces and packaging, expressiveness and quality of inscriptions, signs, technical documentation (brochure, catalog, instructions, passport). Indicators of standardization and unification C and and characterize the degree of use and application of standardized, unified and borrowed components and parts in a given device. The more such elements there are in the designed device, the lower the costs for their design and technological preparation of production, the higher, as a rule, the reliability of operation, and the easier it is to organize maintenance and repair. PATENT LEGAL INDICATORS characterize the degree of novelty of technical solutions in the device and are determined by patentability and patent purity. A patentable solution is one that can be recognized as an invention in one or more countries. Patent purity is granted to solutions that do not fall within the scope (do not infringe rights) of other patents. E conomic indicators characterize the level of costs for the production and operation of the op. Among them, the total cost and the wholesale chain of the device are distinguished. Safety indicators characterize the degree of protection of people and animals from the dangerous effects of devices (protection from electric shock, electromagnetic fields, thermal effects, radiation, optical radiation, noise, toxic and one-time emissions, vibration tions, etc.), as well as the devices themselves from climatic, mechanical, biological and other influences on them. Such indicators, for example, are the category and class of performance and operation. Environmental indicators characterize the degree of harmful influence on the environment and its pollution during the manufacture, operation and disposal of devices. It should be noted that it is during the design and construction of the OP (and not during ero-manufacture, operation) that the potential capabilities of the future device are laid down; the opportunity arises to most effectively increase all 12 ero-quality indicators in comparison with existing technical solutions (prototype) . For example, the consumer cost of devices, the economy of their production and operation, as research has shown, at 75 O/o are determined during the design preparation of production. 1.1.3. STRUCTURE OF AN OPTICAL DEVICE An optical ir device is designed to convert information from an object of observation (detection), measurement or control. In Fig. 1.2 shows a generalized diagram of the q)operation of the op. In optical devices, a transformation of the form y == f(x, Qi)" rе f (conversion function; qi KOHCTPYK active parameters of the device occurs. The input signal is converted by functional devices (FU), which, as a rule, have different physical principles. On Fig. 1.3 shows the composition of the COBpeMeHHoro OP, oCHoBanHoro on optical, mechanical and electronic (electrical) fus and their combination. From a system point of view, the fu is an op subsystem that operates autonomously, but is connected with other subsystems in certain ways (for example, for transmission). information, energy, substance). x x op y == f(x, qi) Fig. 1.2. General scheme of FUIl"tioning of OP: 1 object; 2 OP; V observer; X informative parameter of the object; X informative parameter BXodHOZO signal; The informative parameter is HOZO signal output. 13 mechan.u chesk./Oppl.pl.E"lekpl,RO mechanical"opn/"o mechanical el.e"plron.n.yle and electrical"opn/"o ko elekplron.n.ble Fig. 1.3. Composition of functional al. devices in the OP only (unlike the FU) together with other components. In the CU (Fig. 1.4) it is possible to distinguish the connecting parts (CD) elementary assembly units, which consist of two or more parts that are in direct physical contact with each other. The primary elements of SD, and therefore of the OP of the simplest design objects, are parts (D) structural elements made from a homogeneous material (as a result of ero-processing) without connection with other structural elements (without the use of assembly operations). Thus Thus, the structure of the OP as a whole can be represented in the form of hierarchical levels of the above-mentioned components (subsystems) connected with other specific relations (connections) (Fig. 1.4 I op KB Fig. 1.4. “type of device Methods and principles for designing OP elements” of individual complexity levels have significant differences, so their study usually begins with details, moving from simple to more complex, and ends with FU 14 1.2. PRINCIPLES OF DESIGNING PARTS 1.2.1. DETAILS In this subsection, only some general, as well as specific issues of designing parts are briefly discussed, since students (and other readers) are usually familiar with them to a certain extent from other educational courses and publications. As was said, parts are the simplest design objects. They are indivisible homogeneous bodies, consisting of elements (forms (geometry of the surfaces of bodies) and material. In each part, the following structural elements (surfaces) are distinguished: working (active), basic, connecting (free) and technological. Working elements (RE) (they are also called active or actuating surfaces) directly perform the specified functions of the part. For example, RE are: (rheric surfaces of the lens (Fig. 1.5, a); involute surface of the gear-wheel (Fig. 1.5, b); flat and cylindrical surfaces of the lens frame (Fig. 1. 5, c). These surfaces, as a rule, are carefully processed, and high demands are placed on them: accuracy of position, precision of q) shape, surface cleanliness, dimensions, etc. Vase. elements (BE) provide coordination of the part (i.e. e. coordination of its RE) relative to other parts and represent the surfaces along which the part is mated (connected) with the base part (Fig. 1.5). These surfaces are also prepared very carefully. Connecting elements (CE) (they are often called free) serve to provide a material connection between the working and base elements (Fig. 1.5). SEs are not subject to high requirements for thoroughness and precision of manufacturing (with the exception of requirements for cleanliness of surfaces, when this is due to the aesthetic indicators of the quality of the part). Technological elements (TE) serve to ensure the technological process of manufacturing and subsequent assembly of a part (for example, chamfers, fillets, recesses, center holes in rollers, etc.). For the lens (Fig. 1.5, a) 15 a) BE b) RE c) BE RE TZ RE SE SE Fig. 1.5. Cp py"typHЪLe element (, parts TZ are chamfered, which eliminate chips that appear on the edges during its grinding; for a gear wheel (Fig. 1.5, b) TE is a threaded hole for a locking screw for fixing the gear wheel on the shaft when paCCBep pouring a hole UNDER the pin; in the lens frame (Fig. 1.5, c) TE is the thread (and the groove for the thread exit) for fastening the frame (with the lens) in the centering cartridge for effective processing of its base surfaces to size (see Fig. 1.42). It should be noted that the same surfaces (parts of surfaces) MorYT play the role of RE, BE and SE. The most favorable option is when it is possible to combine RE and BE in the design; the design of the part consists in the choice of material. la, the size of its surfaces and the determination of its dimensions. In addition, the designer must indicate the permissible deviations of the material characteristics, manufacturing tolerances of sizes and shapes, type of coatings, type of processing, technical and technological conditions and requirements (for example, nitriding, antireflection). , aging, etc.). The choice of material is made based on the functional purpose of the part, its operating conditions, rational manufacturing technology, cost and density of the material, ernomics and aesthetics requirements. The designer is guided by the nomenclature, range and physical and mechanical properties of KOH structural materials (Table 1.1). 16 Table 1.1 Mechanical, mechanical and technical properties of materials Properties Characteristics Electromagnetic Constants Spectral Polarization Density Elasticity Hardness Wear resistance Strength p oi"octb flair hazard Radiation resistance Corrosion resistance Water-repellent (moisture resistance) Electrical resistivity Coercive force Magnitic permeability Penetration strength Sliding friction coefficient Rolling friction coefficient Coefficient of adhesion Plasticity Weldability Flexibility Compressibility Toughness processed, "U Optical Mechanical Thermal Chemical, corrosive . Frictional Technological For example, if a lens is designed, then its material must be transparent for the operating range of wavelengths of light. If the lens will be used in conditions of TPO picnic or MopcKoro mat, it is necessary to choose a MaTe material that is resistant to moisture, fungi, salt and other harmful factors. Based on the condition of minimizing mass and the possibility of producing a lens by casting, it could be made of organic glass (if this does not affect other quality indicators of the part). Naturally, the characteristics of the material used must ensure the necessary accuracy of dimensions, shapes and roughness (cleanliness) of the surfaces of the part during its manufacture, as well as maintaining them stable during long-term operation under the influence of various factors. 17 Technological materials are those that can be easily processed by cutting, sanded, stamped, pressed, welded, sintered, and have good casting properties. The general modern trend is the use of materials from which parts can be produced using productive methods ( for example, injection molding, stamping, pressing), as well as the widespread use of plastics. When choosing the material of parts that interact with a person, both directly and indirectly, er-onomic indicators are taken into account: logical, anthropometric and psychoq)isiological (noise level, amplitude and frequency of vibrations, temperature, the possibility of obtaining optimal q)formation, effort , contrast, performance class, degree of utilization, etc.). For example, such a promising material for the production of space mirrors as beryllium, which has a number of very good characteristics for this, is very toxic during processing, which limits its usage. The property of the material also determines the achievement of conformity q) of external parts with their purpose, quality... I \ quality and perfection of finishing, the possibility of applying decorative coatings and other aesthetic indicators. \ B general case The solution to the problem of selecting the LV material of a part is multivariate, since the requirements for accuracy, reliability, weight, strength, rigidity, economy, aesthetics, etc. come into conflict with each other, which has to be overcome by optimizing the choice of material by ranking the importance by .. indicators of the quality of the part and the properties of the material. Very often, the choice of material is made by calculating the required values ​​of HE characteristics according to the required quality indicators (for example, grades and optical constants of glass according to the permissible aberrations of the system, the modulus of elasticity of the roller material according to permissible deformations, coefficients (ratio of linear expansion of the material according to permissible changes in the dimensions of the part when changing temperature, etc.). The designer must constantly monitor the emergence of new materials, and also try to use non-traditional ones (for critical parts) materials that, due to their MorYT properties, increase the quality indicators of the designed product. 18 For example, the production of parts of axial pairs of theodolites not from steel, but from aluminum alloy V95T (which, when hardened and hard anodized, is close to hardened steel in strength and hardness, is well processed, is stable over time, and has a low coefficient (p" q ) friction in a kinematic pair with the same material and retains the lubricant well) makes it possible to reduce the weight of parts and simplify their production and mutual fitting of parts. The use of titanium alloy VT..1 in the manufacture of frames for some optical devices " hoists allows you to avoid their thermal deformation due to the equality (proximity) of the coefficients of linear expansion of titanium and many brands of optical glass. Manufacturing the guides of three-coordinate measuring machines from granite or ceramics makes it possible to increase their manufacturability and a number of consumer properties in comparison with the option when the guides are made of steel or cast iron. The most typical example of the use of new and non-traditional materials in the design of parts is the mirrors of space telescopes, which are currently made from materials such as glass-ceramic, silicon carbide, borosicate, and composites. Important (l)actors that should be taken into account when choosing a material are the available ero assortment and delivery conditions (rods, strips, pipes, sheets, channels, plates, blocks, compacts, their possible sizes, the largest mass of workpieces, etc.). etc.), since the use of assortments and blanks that are similar in (l)opMe and dimensions of the designed part allows one to significantly reduce the labor intensity of its production. Particular attention must be paid to the conditions for the supply of optical materials, since for many types and nomenclature there are significant restrictions in the range and weight of the supplied workpieces, which may not allow the production of parts of the required sizes and (forms) from them or lead to significant costs during their manufacture. Requirements for the materials of optical parts and some of their characteristics and quality indicators will be discussed further in Chapter 7. The choice of the shape of the surfaces limiting the part is carried out based on their structure (functional purpose), manufacturability, aesthetic and ernomic requirements, design feasibility. The shape of the working elements of standard parts is often quite definite. involute surfaces of gear teeth, spiral profile of a cam, etc. The working elements of original parts are made in the form of special surfaces, for example, parabolic, elliptical, toric, etc. The shape of basic, free and technological elements is usually standard surfaces plane, cylinder, cone, cq)epy for optical. More technologically advanced are standard surfaces obtained by processing parts on universal equipment with standard tools. Special q)forms of surfaces are obtained using q)asonary tools, specialized equipment, fixtures, technological processes and control, which significantly reduces their manufacturability compared to standard surfaces. This circumstance can affect the design of not only the part, but also the product. rak, when creating the design of a space-mirror lens for q)imaging the nucleus of comet Halley (international project “Bera”, 1986) from two developed options (one was developed by the q)French Laboratory of Space Astronomy in R. Marseille, another at ITMO), providing the same image quality, the ITMO design was chosen and manufactured, since it was based on spherical mirrors, and the French lens design was based on asq)eric mirror surfaces. It should be remembered that the accuracy of the q)form of the surface decreases with increasing its length, with discrete (zonal) surface processing compared to continuous, with an increase in the number of parameters that need to be maintained during processing. The shape of the surfaces of a part affects the erronomic indicators, determines their appearance, the expressiveness of elements and composition, and is associated with the quality and perfection of finishing. For example, the sensitivity of its movement, the maximum developed force, and the speed of control operations depend on the shape of the device drive control handle. The parameters of the MorYT form can be obtained heuristically, by calculation, based on the conditions of standardization and unification, technological production capabilities, etc. (for example, the radii of curvature of the spherical surfaces of lenses are determined from aberration calculations and rOCTOB on them, yrol the cone of the conical or domed surface of the center hole of the part is assigned based on the type of part, its mass, requirements for processing accuracy and ROCT 14034 74). and is produced taking into account a large number of factors, among which it is necessary to highlight functional accuracy, parametric reliability, rigidity, compactness, aesthetics and ergonomics, manufacturability, standardization and unification requirements, weight and the range of materials used. The designer, guided by the above factors, selects or calculates the required dimensions of the structural elements of the part. In the most critical cases, the parts are subjected to careful calculation (and sometimes experimental research) according to mathematical models, connecting its dimensions (and form parameters) with the required quality indicators, layout, operating conditions, production and other restrictions. As a rule, these are parts that determine the accuracy of operation, the quality of the created image, and which experience significant static, dynamic, and thermal loads (for example, parts of astronomical, military, space instruments). For optical parts, similar calculations (for example, dimensional aberration) determine the size and location of the working elements. Let us consider, using a simplified example, the process of calculating the length and diameter of the roller of a photoelectric converter (sensor) of angular displacements (Fig. 1.6). Under the influence of the torque M, the shaft, and with it the measuring raster, rotate (BoKpyr X axes), modulating the luminous flux , passing through the slits of the indie "KaTopHoro raster, creating a variable on the photodetector electrical voltage, converted into counting electrical pulses, which are a measure of the angle of rotation. , . 21 3 4 5 6 7 8 1 Measure x x x x L t Le Fig. 1.6. Simplified diagram of 1SONSPl,RU1Scui converterP1.el: 1 shaft; 2 Ularikovy nodUlinllIK; In photonreceiver; 4 indicator raster; 5 lenses; 6 Measuring raster; 7 condenser; 8 light source The length of the roller L B is determined mainly by the relationship between the bearings L and the size of the working end of the roller t: usually specified in the technical specifications: L B == L + t. The distance between the bearings determines the angular rotations of the raster BO Kpyr of the Z, Y(ADdr) axes and, as a consequence, the end runout DHdr of the working track of the raster, caused by radial runouts inner rings bearings Dr: DHdr RDUL\r 2Rdr1L, rde R radius of the working path of the raster. The end runout of the raster can lead to defocusing of the image of ero strokes and loss of accuracy of the work of the preformer, therefore in best case scenario it should not exceed the diffraction depth of field of the projection lens T d: 2 XDp< Т д == л/(2А), rде л рабочая длина волны; А апертура объектива. Следовательно, расстояние между подшипниками и ис комая длина Bcero валика зависят от класса точности при" 22 меняемых ПОДШИПНИКОВ И характеристик проекционноrо объектива: L == 4RA2 p/A. Определим диаметр d в-алика. Он может быть найден из условия, что под действием моментов вращения и сопротив лени я Мс валик закрyt.Iивается на уrол OPM, dimensions and relative position of its surfaces for assembly (especially automated assembly, which will be discussed in paragraph 1.3.9). Issues of manufacturability of product designs "< OT работка конструкций на технолоrичность) с оrлас но rOCT 14.201 73, rOCT 14.205 83 должны рассматриваться на всех этапах проектно конструкторской работы и изучают" ся в литературе по технолоrии машиностроения и приборо строения, сборке и юстировке приборов , а также по методам уменьшения издержек при создании и конструи ровании продукции . При конструировании деталей конструктор должен опре делить способ термообработки, тип покрытий и смазочный материал, которые оказывают существенное влияние на по казатели их назначения и особенно надежности. Блarодаря термообработке (закалке, отжиrу, старению) улучшаются, например, характеристики прочности и TBep дости, износостойкости, снижаются остаточные напряжения (вызывающие их деформацию во времени), появляется воз можность получения более точных поверхностей в деталях. П окрытия деталей позволяют защитить их от коррозии (налетоопасности, пятнаемости), улучшить их внешний вид, уменьшить износостойкость, изменить некоторые xapaкTe ристики (например, теплопроводность, электрическое со.. противление, коэффициент отражения). Особенно широко приментотся покрытия оптических дe талей: просветляющие, зеркальные, поляризующие, токопро водящие, покрытия"фильтры, защитные и т. д. (см. п. 8.1.1). Смазочные материалы (замазки) предназначены для уменьшения трения и износа подвижных деталей, защитыI от коррозии, борьбы с «осыпкой, rерметизации и влarо.. и пылезащиты. Вопросы термообработки, покрытий, смазки деталей точ" ных приборов изложены в справочниках , rOCTax и специальной литературе. 1.2.2. ПРИНЦИП СОВМЕСТНОЙ ОБРАБОТКИ РАБОЧИХ И БАЗОВЫХ ЭЛЕМЕНТОВ ДЕТАЛИ Этот принцип заключается в предпочтительности кон" струкции детали, пОЗ80ляющей осуществлять совместную 25 а) БЭ БЭ РЭ 1 "- ,J. , " :"/ 1 I , " " РЭ 2: "/ / б) РЭ 1 РЭ 2 Рис. 1.8. Конструкции оправы технолоzuческую обработку (за одну установку) ее рабочих и базовых элементов, так как в этом случае точность их вза имноrо расположения будет выше. На рис. 1.8 изображены варианты упрощенной KOHCTl1>YK tions of the lens frame, in one of which both working elements (RE 1, RE 2) not MorYT must be processed together with basic element (Fig. 1.8, a), and in others such a possibility exists (Fig. 1.8, b). In the first case, the accuracy of the location of RE 2 relative to RE] and BE will be greater, and, consequently, the centering of the lenses and the accuracy of maintaining the air gap will be worse than in the second option. This is due to the fact that during a rearrangement (technological relocation). frames in the machine chuck arise from the relative position of its RE and BE, caused by changes in the technological and measuring bases. (Fig. 1.9 shows the old and modernized (Fig. 1.9, b) designs of the Relios 44 lens. Frames 8 and 5 of the optical components of the lens (Fig. 1.9, a) do not satisfy the design principle under consideration, therefore the mutual decentration of components 1 and 2 , 3 and 4 are larger than in the modernized design, and to compensate for the errors in the air gaps of the version shown in Horo in Fig. 1.9, a, a compensation ring 6 is required. However, in the design shown in Fig. 1.9, b, principle 26 a) 5 b) Fig. 1.9. The quality of the lens for joint processing of RE and BE is not satisfied by the body part 7, which may negatively affect the quality of alignment by components 1, 2 with 3, 4. 1.2.3. PRINCIPLE OF PRECISION TECHNOLOGY OF PARTS This principle consists in taking into account environmental factors when assigning tolerances to the characteristics of the material of a part and to the accuracy of its manufacture. The designer must remember that the cost of the part largely depends on the tolerances. So, the higher the quality of the material used, the more expensive it is. For example, the cost of optical glass of the first category, class A, in terms of refractive index and average dispersion, is several times higher than glass of the same brand of the fifth Ka theory, class R, and the cost, taking into account all quality indicators, can differ by an order of magnitude. In Fig. Figure 1.10 shows a graph of the relationship between the tolerance 8q for the manufacturing accuracy of the part and the costs for its implementation ZBq. The graph shows a curve formed by sections of equilateral hyperbolas 1 4, characterizing the costs of obtaining approval when processing a part on various equipment using various tools, equipment, etc. Nodal points E, P, T, formed by the intersection of the corresponding curves, are the boundaries of the zones characterizing low, medium and high costs and co.. Fig. 1.10. 3depending on the cost of m. OCn1 and On1 - the corresponding levels of accuracy with iseOnl, over the limit of denl, or low, medium and high accuracy of technological processes, called economical. II, production and technical. The economic (reduced) level of accuracy (EL) of technological processes (the tolerance is indicated by 8q corresponds to the accuracy obtained in mass production when manufacturing parts on automatic and universal equipment using standard tools, equipment and devices. Control is carried out by means located at the workplace (micrometers, indicators, calibers, standard glasses). For optical industry factories, the economic level on average begins with 9 1 O"ro accuracy levels. (PUT) corresponds to an accuracy of 8q, obtained in serial production when manufacturing parts also automatically and universal equipment, but with the use of special tools, equipment and technological processes (for example, in the manufacture of parts: on grinding machines; using diamond cutters; reamers; jigs.. conductors; devices for centering the workpiece; with an increase in the number of repeated cycles "< выхаживанием) обработки поверхностей детали и т. п.). Контроль произво" дится средствами, находящимися как на рабочем месте, так и в отделе техническоrо контроля (ОТК) цеха. Производствен" 4 3 о Д бq т бq п бq э 28 ному уровню соответствуют в среднем допуски по 6 8 MY квалитетам точности. Техническому (высокому) уровню точности (Т"У"Т) COOT ветствует предельно высокая точность 8q , которая может т быть достиrнута с помощью специальных (прецизионных) оборудования, инструмента, технолоrических процессов и условий производства. Например, для достижения точности нанесения делений на штриховых лимбах (диаметром око.. ло 100 мм) с поrрешностью 1 2" используют прецизионные делительные машины, производят стабилизацию темпера" туры (до COTЫ долей rpaдyca), давления и влажности в рабо \ чем помещении, осуществляют защиту от вибраций и друrие мероприятия. Контроль деталей выполняют с привлечением лабораторных средств (автоколлиматоров, микроскопов, ин Tepq>epoMeTpoB). Technical level correspond to 4 5 MY qualifications. More high accuracy The production of a part (zone D) can be obtained by finishing it, performed on machines, or by manual metalworking (scraping, lapping, reaming, rolling, etc.), as a rule, during the process of assembling the part into a unit (usually this process is called technological compensation of parts errors). passing through the nodal points E, P, t and characterizing the relationship between tolerance and execution costs: t ZBq 2t + Z05q, 8q (1.1) exponent (it is usually considered that t == 0.5 -7 1); ZOBq cost of manufacturing (an element) of a part according to a free tolerance. Thus, when assigning high (tight) tolerances to the manufacturing accuracy of parts, the designer must be aware of the that this will lead to a significant increase in their cost, therefore such tolerances must be justified by other factors related, for example, to the costs of 29 Zoq \ , \ \ \ \ \ \ \ \ \ , "".. ...... ...-... ......- 3 I ,/,/,//" 1 assembly, accuracy of q)operation of the Bcero device, etc. The cost of assembling parts, as is known, depends on their accuracy production (Fig. 1.11, curve 2) and can be characterized by the dependence: Z8q == R8 q 2r + R 08q , (1.2) bq r de R coeq (rient for expressing tolerance in units of cost; r> O exponent ; R 08q cost of assembly in the absence of imperfections. This dependence is due to the fact that assembly costs increase with increasing manufacturing accuracy of parts, since large parts usually require additional adjustments, fittings, and adjustments during assembly (their capacity is much greater) , and also make it difficult to use funds automatic assembly . In general, the designer, when assigning tolerances, must take into account the costs of manufacturing and assembling parts (Fig. 1.11, curve 3), assigning, if possible, tolerances that correspond to the economic levels of accuracy, manufacturing and assembly. In the future, we will consider some problems associated with the study of dependencies 1 and 2 and taking into account economic factors when calculating tolerances. Fig. 1.11. Dependencies The accuracy of their construction 1.3. PRINCIPLES OF CONSTRUCTION OF CONNECTIONS The connection of parts in the design sense (as a structural element) is the design of an elementary assembly unit, which consists of two or more parts that are in direct contact with each other. . The connected parts form contact pairs, which are classified as: movable and fixed; connection lConnection of parts in the technological sense (as an assembly operation) is the joining of parts by joining, screwing, flaring, welding, etc. 30 a) 1 b) r .... " / " ;B l l / ; / ;" A 71 L t 2 le; fVT 1 3 lA SV Ci"l BESU d,/ RE 2 BES I ll, AB i B l L .! BES RES "RE 1 Fig. 1.12. Elements, joints of den/,alized by q)shape, force and fastening; mating (copying.. tacting) along the surface, along the line and at the point. In the connection, there is a basic and working (attaching "main) parts, as well as basic (UES) and working (RES) elements (surfaces) of the connection. In Fig. Fig. 1.12, and shows the connection of dial 1 with shaft 2. The base part here is the shaft, and the working dial, the basic element of the connection of the shaft pin for bearings, the working element is the surface of the dial, on which the divisions of ero strokes are placed. In Fig. 1.12 , b shows the connection of the lens (working attached part 1) with frame 2 (base part) using a threaded ring 3, which is an auxiliary part in the connection that forces the lens to the end mounting surface of the frame. Indicators of the quality of connections are divided into: operational. (accuracy, reliability, wear resistance, load-bearing capacity, etc.); structural (dimensions, weight, compactness, etc.); technical characteristics of assembly, adjustment and control. connections, first of all, they try to achieve their accuracy (characterized by the accuracy pac of the position of the RES relative to the BES, Fig. 1.12), reliability and manufacturability. Let us consider the principles of designing connections that make it possible to ensure these indicators, based on 31 general rules and laws for the imposition of material connections of parts. each other in connection. 1.3.1. PRINCIPLE OF COMBINING WORKING ELEMENTS IN A JOINT When designing joints, the preferred design is one that allows the KOH stroke of the mating parts to be carried out along their working elements. In this case, the working and base elements of the joined part are combined, the dimensional chain is reduced and the accuracy of the location of the RES relative to the BES is increased. For example, in the case of the location of the dial strokes on the surface r (see Fig. 1.12, a), the principle will not be fulfilled, since the working element (surface D) of the base part (roller) is not combined with the working element of the attached part. In the case of the location of the strokes of the dial on surface B, along which the l:i:mba is interfaced with the surface D of the roller, the principle is observed, and it can be argued that the accuracy of the location of the RES relative to the BES (tacq) of the roller) will be higher than in the first case . Part 1 will be more technologically advanced, since there is no need to maintain strict tolerances for its wedge shape compared to the first option. a) b) 1 2 2 1 BE 1 BES (BE 2) "" BES (BE 2) Fig. 1.13. Connecting a mirror with a frame 32 In Fig. Figure 1.13 shows the design of the connection between mirror 1 and bracket 2. The design shown in Fig. 1.13, b, makes it possible to more accurately orient the reflecting surface of the mirror (RES) relative to the base of the KpOH matte (BES) and does not require strict tolerance for the wedge shape of the mirror in comparison with the design shown in Fig. 1.13, a. 1.3.2. the principle of the ABSENCE OF EXCESSIVE BASEMENT IN THE CONNECTION OF PARTS (STATIC DEFINITENESS OF I CONNECTIONS) Giving material bodies a definite and fixed position in space is called basing. When basing, the excess degrees of freedom of the attached part relative to the base part in their connection are taken away. Basing is called redundant when the extra degrees of freedom of the attached part are taken away more than once, i.e. when more than one connection is made to take away the extra degree of freedom Ha. The relationship between the remaining degrees of freedom n and the number of superimposed bonds m should be n + m == 6. To identify excess (or insufficient) bonds in a connection, use the q) formula Ddtf [""1,3)""1 k==5 q == n + "LPkK 6, k==l (1.3) rde P k is the class of an elementary pair of contact, which determines the number of degrees of freedom taken away by the pair (for example, with contact at point P 1 == 1; with contact at lines р 2 == 2; for contact along a plane Р 3 == 3; for contact along a cylindrical surface Р 4 == 4; for contact KOHYC KO nus, screw Р 5 == 5, in table. 1.2 shows the classes of a number of elementary contact pairs); K is the number of pairs of a given class. If q is equal to zero, then the location in the connection is correct; if q is less than zero, then the attached OCTa part has excessive degrees of freedom; if q is greater than zero, this means that there is redundancy in the connection. 33 Contact of mating surfaces of parts Along a point Along a line; two points; ring line Pair class (number of subtracted degrees of freedom) P...-, 1 P2 2 KL,assy" el,ementarny"x xontaxtnbl"x pairs Combinations<рорм поверхностей де1"алей в соединениях т аблu ца 1.2 Сфера цилиндр Сфера сфера "z Сфера плоскость Цилиндр цилиндр Z. 7 Цилиндр пло Сфера призма скость Сфера цилиндр Цилиндр цилиндр P2(Z, <ру) Z х.. Р 2 (У, Z) Р 2 (У, Z) По плоскости; Рз Плоскость пло.. Сфера конус Плоскость кольцевой ли.. скость три сферы нии; cqJepe; трем.Z Z" точкам,У, r · ... Х " Р З (Zt Excessive basing can lead to uncertainty in the position of the working elements of the connection relative to the basic ones, the occurrence of deformations of parts, and the complexity of their assembly (i.e., such a relationship will not be accurate, reliable and technological). For example, for connecting the slider 1 ( Fig. 1.14, a), moving along the axis with the cylindrical guide rods 2 and 3, we obtain q == 1 +4 2 6 == 3. This design has redundant basing (three of... redundant connections), in As a result, due to errors in the manufacturing of parts (accuracies in interaxial distances, non-parallelism of holes in the slider and shaft axes), deformation of the slider and jamming during movement may occur, especially in the case of temperature fluctuations. This can be avoided either by large gaps in the guides, which will lead to a loss of accuracy, or by careful adjustment of the cylinders, which will significantly increase the labor intensity of assembling the joint. The design of the slider, shown in Fig. 1.14, b, is free from these shortcomings: q == 1 + 4. 1 + 1 . 1 6 == o. in some cases, a violation of the principle can be seen with the naked eye by duplicating the interfaces of parts (basic elements), taking away the same degrees. 1.14. Connection of the slider with the guides 36 a) 2 no freedom in the attached part relative to the base one (Fig. 1.15, a, c). The uncertainty of basing can be eliminated either by changing the design of the mating parts (Fig. 1.15, b), or by carrying out a joint technological COOT treatment of the relevant surfaces of the mating parts (size n bracket1 and base 2, Fig. 1.15, c). In those connection designs in which the mating of parts is carried out simultaneously along two surfaces (Fig. 1.16), the theoretical uncertainty of basing in a real structure can be avoided by controlling the corresponding dimensions of the mating surfaces or tolerances on their precision. In Fig. 1.16, a shows the design of the connection between the lens frame and the tube, which has a centering belt c) Double in Z,<Рх, <ру б) Рис.l.15.ДуБЛl.lрование в сопряжении деnl,алей а) б) t , ! J L«D Дубль по Х, У, <Рх, <ру " v , Дубль по <рх,<ру Рис. 1.16. Сопряжение деталей в соединении по двум nоверхностям. 37 и резьбу для фокусировки объектива. Чтобы не возникало избыточности базирования в этих сопряжениях, необходи" мо посадку резьбы ПрОИ3БОДИТЬ с r"арантированно большим зазором по сравнению с зазором посадки цилиндричеСRоrо пояска. На рис. 1.16, б представлено соединение вала с подшип" ником, в котором наклоны вала BOKpyr осей Х, У отняты сопряжением ero с подшипником и ПО плоской, и по цилин" дрической поверхностям. Реальное дублирование может возникнуть здесь из..за равенства соответствующих баз (D, L) поверхностей, оrраничивающих повороты (см. п. 1.3.6). Для устранения реальноrо избыточноrо базирования в подобном соединении следует ero конструкцию изменить так, чтобы одна из баз была бы MHoro меньше друrой (рис. 1.16, в, z). в ряде случаев проверка соединения на избыточность ба" зирования требует тщательноrо анализа, поскольку ero ре" зультат не так очевиден, как в рассмотренных примерах. На рис. 1.17 показана типовая конструкция соединения (крепления) плоско"выпуклой линзы с оправой с помощью резьбовоrо кольца. Если q)ормально подойти к определению \ класса элементарных пар контакта в этом соединении, мы должны записать, что: контакт сq)ерической поверхности линзы с буртиком оправы (рис. 1.17, а) является парой тре" тьеrо класса (Р 3) и отнимает смещение линзы по осям Х, У, z; посадка линзы в оправу по цилиндрической поверхности является парой четвертоrо класса (Р 4) и отнимает у линзы Р2 (Х, У) Р 4 (Х, У, <Рх, <ру) Р3 (Z, <Рх, <ру) а) Рз(Z,Х, У) Р 4(Х" У, <Рх,<Ру) Р2(<РХ,<РУ) б) D п Рис. 1.17. Крепление линзы в оправе реаьбовым "ольцом 38 смещения по осям Х, у и повороты BOKpyr этих осей <Рх, <ру; резьбовое кольцо, замыкающее линзу на буртик о-правы (по оси Z), воздействуя на плоскую поверхность линзы, отнима ет у нее повороты BOKpyr двух осей <Рх, <ру. Поворот линзы BOKpyr оси Z(2р (friction р yrol), i.e. approximately ШIО: D D 2R > 2/! ::::: 0.3, (1.4) rde R is the radius of the lens; Jl is the sliding friction coefficient of the material of the frame and lens. When this relation is not BY Completed, in conjugation otni FD l t F tr Fig. 1.18. CaMoceNtrirov "a lens" in frame 39 is subject to displacement along the Z axis and rotations BOKpyr of the X, y axes (<Рх, <ру). Рассмотрим сопряжение линзы по посадочному цилин дру диаметром D л с отверстием оправы. Как известно, эта посадка должна быть с rарантированным зазором. Поэто МУ при выполнении условия (1.4) линза не контактирует с оправой (рис. 1.18) по цилиндрической поверхности диа" метром D л, и это сопряжение не должно учитываться при определении избыточности базирования в соединении. Co пряжение цлоской поверхности линзы с резьбовым коль.. цом, как было сказано, оrраничивает повороты линзы (во" Kpyr центра кривизны сферической поверхности) по осям Х, У. Следовательно, данное соединение является статически определенным: q == 1 +3 . 1 + 2 . 1 6 == о. Коrда условие (1.4) не выполняется, смещения линзы вдоль осей Х, у оrраничиваются ее сопряжением с оправой по посадочному цилиндру, а смещение вдоль оси Z торце" вой кромкой оправы. Сложнее обстоит дело с анализом оrраничения поворо" тов. Повороты BOKpyr осей Х, у оrраничиваются и торцевой кромкой оправы, и цилиндрической поверхностью поса.. дочноrо отверстия и, вроде бы, резьбовым кольцом. Одна" ко из..за Toro, что база торцевой кромки, оrраничивающая повороты, MHoro больше соответствующей базы (длины) I цилиндрическои поверхности линзы, а также вследствие Toro, что усилия, развиваемые резьбовым кольцом, не при" водят к развороту линзы, следует считать, что в реальной конструкции именно торцевая кромка будет определять уrловое положение линзы. Таким образом, при невыполнении условия (1.4) соедине ние не будет иметь избыточноrо базирования, однако роль поверхностей оправы в оrраничении подвижности линзы будет иной. "Указанное обстоятельство приводит к тому, что требования (допуски) к параметрам оправы линзы, резьбово" му кольцу и линзе соединения на рис. 1.1 7 будут раз н ы м и в зависимости от условия (1.4). Например, при выполнении условия (1.4) в соединении, показанном на рис. 1.17, а, отверстие оправы диаметром D должно быть соосно С базовой осью Br оправы, а в соедине" нии, показанном на рис. 1.17, б, этой соосности не требуется, 40 а) б) Цш Наllра ленuя 1."350 llере.меll енuя резца Рис. 1.19. Требования 11: оправе при выnолн-ении условия са.моцен-пtрuров"u ЛUН-ЗЪ/. но зато требуется соосность резьбовоrо отверстия М. Допуск на центрировку самой линзы может быть более широким (свободным) по сравнению со случаем, коrда условие (1.4) не выполняется. Перпендикулярность торцевой по"верхности резьбовоrо кольца к ero резьбовой поверхности будет иметь жесткий допуск в случае выполнения условия (1.4) и широ" кий в случае ero невыполнения. Анализ данноrо соединения на избыточность базирова" ния заставляет конструктора обратить внимание на такие «мелочи, которые часто выпадают из ero поля зрения. Так, опорная кромка буртика оправы не должна иметь rpaTa и за.. усениц, поэтому направления движения резца,."tолжны быть от кромки в «тело детали (рис. 1.19, а, б) при ее обраб,отке. В случае, коrда для уменьшения де(l)ормации кромки апра" вы и линзы при закреплении последней кромку выполняют под уrлом 1350 либо под уrлом, касательным к сq)ерической поверхности линзы (рис. 1.19, б, в), необходимо обеспечить расположение вершины конической поверхности кромки на базовой оси оправы. . . 1.3.3. ПРИНЦИП rЕОМЕТРИЧЕСКОЙ ОПРЕДЕЛЕННОСТИ КОНТАКТА ПАР В СОЕДИНЕНИИ Этот принцип заключается в определенностu положенuя и формы контакта сопряzаемых поверхностей деталей. Реальные поверхности деталей имеют макро" и микропо" rрешности формы поверхностей. В результате детали кон.. 41 а) 3)) \ / \ I б) F Рис. 1.20. Сопряжение.зер"ала с оправой тактируют друr с друrом не по линиям и поверхностям, а по пятнам (площадкам) неопределенной (рормы, размеры и по ложения которых в сопряжении также неопределенны. Эта неопределенность снижает точность расположения присоединяемой детали и несущую способность базовой дe тали. Наибольшее влияние на точность оказывает не9преде ленность расположения пятен контакта. На рис. 1.20, а изображено соединение зеркала 1 с опра вой 2 с помощью трех уrольников. Из за поrрешностей фор" мы сопряrаемых поверхностей зеркала и оправы их контакт будет происходить не по плоскости, а по трем площадкам 3, расположение и форма которых MorYT быть произвольными в пределах сопряrаемых поверхностей. В результате возни z б) у а) Х. у в дС z z х в) Х у I C C Рис. 1.21. Соnряженu.е осей с nодшипни"ами 42 кает объемная деформация зеркала под F действием сил F со стороны уrольников и...... реакции R со стороны оправы, приводя щая к порче качества изображения. Соединение, изображеIПIоенарис.1.20, б, обладает определенностью расположения площадок контакта блarодаря специаль ным выборкам (либо прокладкам) на опра ве. Здесь возникает только контактная деформация зеркала в пределах контакти рующих зон,.. не приводящая к ухудшению качества изображения. Неопределенность расположения и фор мы контакта цилиндрической оси Bpa Рис. 1.22. Сопряжение щения с подшипником (рис. 1.21, а) не менис"а с оnрав.ой позволяет определить базу В между элементами поверхно сти, оrраничивающими ее наклоны BOKpyr координатных осей Х, У, требует тщательной обработки всей поверхности и отсутствия бочкообразности. Выборка на поверхности оси (рис. 1.21, б, 8) приводит К соблюдению рассматриваемо ro принципа и позволяет избежать упомянутые HeДOCTaT ки конструкции соединения." По этим причинам осущест вляют также выборки на протяженных поверхностях ползунов или направляющих поступа тельноrо движения (см. рис. 1.26). Выборки на торцевой опорной поверхности оправы под линзу (рис. 1.22) позволяют соблюсти также принцип силовоrо замыкания этоrо соединения, изложен ный в следующем парarра(l> e. 1 1.3.4. PRINCIPLE OF FORCE CLOSING Force closure of connections should be carried out so that the line of action of the closing force passes through the contact zone (platform) of the mating surfaces. Then the force and the resulting reaction do not form a torque acting on the attached and base parts. Examples of this MorYT principle are the considered mirror mounting (see Fig. 1.20, b), as well as the well-known method of fastening a thin lens, which rests on three protrusions of the frame using a threaded and elastic ring, which has three protrusions that are located 43 against protrusions of the frame (see Fig. 1.22), using a guide key (screw) 1. When a connection transmits force (brackets, gear and friction pairs, clutches, etc.) or distribution of forces is required (unloading of mirrors, rotation supports, etc.), one should be guided by the principles of force transmission (straight Mozo and KopotKozo paths, coordinated НIlЪLХ deformations, N;OMpeH F F F Fig. 1.23. Distribution of the mass of the part on the supporting points Ar 1A Fig. 1.24. Raaeruz "a, M, ass. mirrors for 18 supports: 1 support ; 2 unloading platform; 3 spherical hinge 44 force distribution, defined by MI in work. For example, Fig. 1.23 shows schemes for minimizing the de(l)ormation of a part under the influence of force F (for example, mass) when installing it. on several points of support. Fig. 1.24 shows the design of the telescope mirror, which allows minimizing the deformation of the mirror due to the uniform distribution of the mass on 18 supports. e: My parts relative to the base one should be positioned perpendicular to the direction of the zero displacement. In this case, the location of the working elements of the connection relative to the base ones is more accurately ensured, the power mode in the connection will be more favorable (associated with the deformation of parts, their wear), and the parts will be more technologically advanced. In Fig. Figure 1.25 shows two options for limiting the CMe movement of rod 1 along the Y axis by part 2. In Fig. 1.25, and the surface of part 2, which limits the displacement of the rod, pac is placed perpendicularly, and in Fig. 1.25, b at an angle of 900 a to the Y axis. As a result, for the first option, the dimensionality of the rod position along the Y axis due to the dimensionality dq (for example, roughness) of part 2 will be equal to the dimensionality itself: dU dq dq; and in the second option it will be greater: АУдq dq/cosa. a) 2 b) l 1 2 1 "* 1"""" "1 o o s l" , " , " " "1 Fig. 1.25. COLLECTIONS OF THE ALLIANCE OF DISPLACEMENTS INTO"a 45 C C Z y b // B B Fig. 1.26. Tiny guides of progressive movement The reaction R from the side of part 2 to the closing force 8 in the first version is equal (without taking into account friction forces) to the force itself: R 8; and in the second option it is greater: R 8 jcos a (i.e., there will be more wear on parts). In addition to this, a component force T == 8 tg a appears, which can lead to bending and rotation (relative to the X axis) of the rod in the guide gap. When manufacturing in the first option, it is necessary to ensure the l parameter, while in the second case, the l and a parameters are provided. Thus, using this elementary example, one can be convinced that adherence to the principle of limiting the movement of parts in connections makes it possible to increase the accuracy, reliability and manufacturability of the design. Consequently, cylindrical guides Bpa of careful motion are preferable to conical ones (see Fig. 1.21, c), and guides of translational motion of the T-shaped type are better than dovetail XBOCT type guides (Fig. 1.26). The accuracy of cam mechanism 1 with a smaller pressure angle 1 will be higher than that of mechanism 2 with a larger pressure angle 2 (Fig. 1.27). The accuracy of the transmission of motion by a screw mechanism with a sharp-angled thread is greater than with a trapezoidal thread 2 1 C " . " / 1 1 ]! j / / / / / / / / / / / / Fig. 1.27. Flat "ulch" and 46 a) c) b) 300 Fig. 1.28. Screw mechanisms. thread and tape (Fig. 1.28, a c), or when the screw is made with a trapezoidal thread, and the nut with a straight tape accurate (Fig. 1.28, z). In Fig. 1.29, a part of the lens design is shown, the air gap d between the KOToporo lenses is maintained using an intermediate ring of size l. Due to the violation of the principle of limiting displacements, the accuracy of the air gap d will not be affected. only the accuracy of the ring size l, but also the accuracy of the ring diameters D 1 and D 2. For example, D 1 (1 1) !J.d6. radii of sq>eric lens surfaces. In addition, this connection can be critical to temperature changes at various coefficients a) l ..... q C\I q d b) C\I q ..... q d l Fig. 1.29. Volume "nl,iv 47 z y x / / / , / / ​​// // 2 Fig. 1.30. A unit of movable "apept" linear expansion of the lens and ring materials, leading to a difference in changes in the corresponding diameters of the ring and lenses, causing the appearance of deformations and decenterings of the optical components. “The elimination of these shortcomings is achieved in HEKO designs by making lenses with a so-called U-shaped collar (Fig. 1.29, b), which makes it possible to observe the principle of limiting displacements. Violation of the principle under consideration leads, for example, to the fact that when fixing the position movable carriage 1 carrying the projection system of the universal measuring microscope "UIM 23", screw 2 causes a significant displacement along the X axis (Fig. 1.30). It is more correct for dovetail guides to carry out fixation in the direction of the Y axis; FOR KOToporo, the principle of limiting displacements is observed. 1.3.6. PRINCIPLE OF TURN LIMITATION. According to this principle, the connections imposed by the base part on the attached part should be located on the largest possible basis. Then the accuracy of the position of the attached part, all other things being equal, will be the smallest. In Fig. Figure 1.31 shows diagrams of the design of the connection of shaft 1 with bearings 2 for rotating the BOKpyr mirror of the Y axis. The option shown in Fig. 1.31, a, is inferior to the option shown in Fig. 1.31, b, since the base Bl between the bearings, limiting possible rotations of the shaft relative to the Z, X axes (for example, due to runout p BHYTpeH 48 a) in 1 L b) B 2 z x y ", y Fig. 1.31. Axial mirror system of bearing rings x == Hz z == L x == L z == N x 8 y == N x Functional devices (FU) are more complex than connections, assembly units, consisting of a larger number of parts and elements that can be performed together with other components of the OP (or independently) a certain (l>Function. This is, for example, lenses, eyepieces, mechanisms, scanning devices, devices for mounting radiation sources and receivers, shutters, diaphragms, stages, sensors, etc. In units and units, it is advisable to distinguish between working (executive), basic (bearing) and reference ( exemplary) parts and working (REU), basic (REU) and reference (EEU) elements. Main indicators of the quality of components and the accuracy (location of the REU relative to the EEU and EEU) of information transfer and conversion, quality of the created image, reliability and manufacturability. The principles discussed in the following sections consist of general rules for the design of mechanical and optical FUs of a device, which make it possible to optimize their structure, internal connections and interaction of elements in order to increase the mentioned quality indicators of the created FUs. 1.4.1. ABBE PRINCIPLE According to this principle, also called the principle of exclusion of comparator area, the reference element of the device must be located COOC1l0 with the working element (or the measured object). In this case, the accuracy of the mutual linear arrangement of the reference and working elements decreases when rotations of parts occur due to technological or operational errors (gaps, errors (shapes of contacting surfaces, deformations, bumps, etc.). Fig. 1.44 shows a classic example, which gave the second name to the principle with transverse (Fig. 1.44, a) and longitudinal (Fig. 1.44, b) comparators. A reference E and are installed on a carriage moving along the Y axis. verified 61 P scales, the relative positions of the lines of which are measured using reading microscopes M 1, M 2. In the transverse comparator, due to the rotations of the carriage (q>z) BOKpyr of the Z axis, caused by the errors of the guides, a significant measurement error Yl arises first-order smallness, proportional to the distance H between the scales (Fig. 1.44, c): Yl == Hsin q>z H q>z. To eliminate the first-order discrepancy, Abbe proposed placing the reference and calibrated scales co-axially, transforming the comparator into a longitudinal one ( Abbe comparator). In this case, the measurement accuracy due to the rotations of the carriage will be only BToporo of the order of smallness (Fig. 1.44, z): Y2 == L L" == L2sin 2 (q>/2) L(q>2/2). Let's look at typical examples of compliance and violation of this principle in some operational devices. In Fig. Figure 1.45 shows the measuring quill 1 of the length-measuring machine, moving into the ball-bearing guides 2. The reference element of the quill is the measuring raster (diffraction grating) 3, which is installed to comply with the Abbe principle coaxially with the tip (RE"U) in contact with the measured object. If only the raster was installed as shown """"""""""""""""""""""" a) i(n b) 4 (M 1 X..... D<Рz ........, в) /11 е) , 1 I , н v . 11 , I I L" i"l ДУ2/ 2 L ДУl Рис. 1.44. Ko.м.napaп opы 62 штриховой линией (на верхней поверхности пиноли), то из за неизбежных поворотов пиноли при ее движении вдоль оси у возникала бы зна"чительная поrрешность измерения. С явным нарушением принципа Аббе выполнена KOHC трукция оку лярноrо микррметра типаМОВО (rOCT 786 5 7 7), схема KOToporo изображена на рис. 1.46. Перемещение у марки подвижной сетки осуществляется rайкой 5 при повороте винта 6 и связано с поворотом лимба зависимостью у == Z3 k p х, Z4 21t rде Z4, Z3 числа зубьев соответствующих колес; k и р чис ло заходов и шаr резьбы винтовоrо механизма; х уrол по ворота точной шкалы. При движении сетки из за поrрешностей направляющих происходит ее ПОБОрОТ BOKpyr ОСИ Z(z Hl

Expand ▼