【溫馨提示】 dwg后綴的文件為CAD圖，可編輯，無(wú)水印，高清圖，，壓縮包內(nèi)文檔可直接點(diǎn)開預(yù)覽，需要原稿請(qǐng)自助充值下載，請(qǐng)見壓縮包內(nèi)的文件，所見才能所得，下載可得到【資源目錄】下的所有文件哦--有疑問可咨詢QQ:1304139763 或 414951605

Mechanical design According to user requirements of special mechanical working principle, structure, movement, power and energy transmission, various parts of the material and shape size, lubrication methods for design, analysis and calculation and mechanical design Translate them into a specific description to be made based on the workingprocess. Mechanical design is an important part of mechanical engineering, machinery is produced in the first step, is to determine the mechanical properties of the main factors. Mechanical design goal is: in various limited conditions (such as materials, processing ability, theory and calculation method of design of the best machinery ), i.e. to make optimization design. Optimization design to consider the many requirements, generally : the best performance, the minimum cost, the minimum size and weight, use the reliability, minimum consumption and the minimum environmental pollution. These requirements are often contradictory, but their relative importance for the mechanical type and use vary. The designer's task is to weigh up one thing against another according to the specific circumstance, take all factors into consideration, make the design of the mechanical optimal comprehensive technical and economic effect. In the past, optimization design depends on the designer's knowledge, experience and vision. As the base of mechanical engineering theory and the value engineering, systems analysis and other new disciplines in the development, manufacture and use of technical economy the accumulation of data, as well as computer application, optimize gradually abandon the subjective judgment and rely on scientific computing. In the service of different industry different machinery, application of different working principle, requires a different function and characteristic. Industrial machinery design, especially the whole and the entire system of mechanical design, must be attached to the relevant industrial technology to form an independent discipline. So the design of agricultural machinery, mining machinery, textile machinery, automobile design design design, ship design, design of pump, compressor, turbine design, engine design, machine design, professional mechanical design branch. However, many of these professional design and many common technologies, such as the analysis and synthesis of mechanisms, and can analysis and calculation, engineering materials, strength of materials, transmission, lubrication, sealing, and standardization, reliability, process optimization. In addition, there are research design work of the inherent law and the rationality of the design methods and steps of the new design methodology. The mechanical design of the general technology and rational design methodology brings together into an independent, comprehensive mechanical design is mechanical engineering practice and education workers are working hard. A machine quality basically depends on the quality of design. Manufacturing process on the quality of the machine the role, essence is to realize the design required quality. Therefore, the machine's design phase is the key decision machine. Mechanical design The discussion of the design process refers only to the narrow sense of technical design process. It is a creative process, but also a try best to use the successful experience of the job. Be well to the inheritance and innovation to combine, in order to design a high quality machine. As a complete machine, it is a complex system. To improve the design quality, must have a scientific design program. Although it is not possible for a list of valid in all cases only program, but, according to the long term experience, a machine design process basically can be as shown in Table 2- 1. 1for each stage are respectively brief description. ( a ) the planning stage in accordance with the production or life presents the need to design new machines, the planning stage is a stage of preparation. At this time, to design the machines only a vague notion. In the planning stages, to deal with the design of the machine needs to do the full investigation and analysis. Through the analysis, to further clarify the machine the function that should have, and for the subsequent decision proposed by the environmental, economic, and processing time and other aspects of the identified constraints. Based on this, clearly written assignments on the overall requirements and design details, finally forms the design task book, as the stage summary. The design task book generally should include : the machine function, economy and environmental protection estimates, manufacturing requirements with respect to roughly estimate, basic requirements, and completed the task of design is expected duration. At this point, the requirements and conditions in general can only give a reasonable range, but not the exact number. For example can be used must meet the requirements, minimum requirements, hoping to reach the requirements shall be identified. ( two) scheme design stage the stage of design play a key role. In this one phase is also fully demonstrated the design work have multiple solutions ( solution ) features. The function of the machine analysis, is to design of the proposed machine function must meet the requirements of the minimum requirements, and hope to achieve the requirements of comprehensive analysis, namely, these functions can be realized, a number of features with no contradiction, can substitute each other. Finally determines the functional parameters, as the basis for further design. In this step, want appropriate processing need and possibility, the ideal and the reality, development goals and the goals may arise between the contradictory problem. To determine the functional parameters, then propose possible solutions, which is made possible by the plan. Seek solution, according to the driving part, a transmission part and execution part are respectively discussed. , more commonly used method is to first from the operative portion began to discuss. Discuss machine execution part, the first is about the working principle of selection. For example, the design and manufacture of screw machine, its working principle can be used in the cylindrical blank by turning thread approach, can also be used in the cylindrical blanks with thread rolling die rolling thread approach. It puts forward two kinds of different working principles. Its working principle is different, of course, the design of the machine will fundamentally different. Special is to be stressed, must continue to research and development of new working principle. It is an important way of the development of design technology. According to the different working principle, can develop a variety of different execution mechanism scheme. For example, only the thread cutting, can use the workpiece can only rotate and tool for linear motion to the cutting thread ( such as in lathe cutting thread ), also can make the workpiece is fixed and the cutter to rotate and move to the cutting thread ( such as die processing thread ). That is to say, even for the same kind of work principle, also may have several different structural schemes. The original motivation scheme also can have multiple choice. Because of the power supply of the universality and the electric drive technology development, it can be said that the vast majority of the fixed mechanical is preferred choice as prime mover part of motor. The original motivation for transport, the main thermal engineering machinery and agricultural machinery. Even with the motor as the motive, there are both AC and DC selection, high speed and low speed selection. The transmission part of the scheme is more complicated and diverse. For the same transmission task, by a variety of institutions and different body combination to complete. Therefore, if the prime mover Part IV, said the number of possible schemes, N2and N3respectively representing the transmission part and the execution part number of possible schemes, then the machine the overall number of possible schemes of Ni x N2x N3. The above is only on the machine is composed of three main parts to discuss the. Sometimes, also considering the configuration assistant system, in this regard, books no longer discuss. In so many programmes, technically feasible only a few. On the several feasible solutions, from technology and economy and environmental protection and other aspects of a comprehensive evaluation. Evaluation of the method are many, now with economic evaluation for example omitted description. According to the economic evaluation, it is necessary to take into account the design and manufacture of economy, should cost taken into account when using economy. If the machine structure is more complex, its design and manufacture cost is relatively increased, but its function will be more complete, productivity is higher, so the use of economy is also good. In turn, the structure is relatively simple, the function is not complete machinery, design and manufacturing cost is less, but the use of cost will increase. Evaluation of structural scheme design and manufacturing economy, can also be used to represent the cost of unit efficiency. For example, the unit output power cost, unit cost. Machine evaluation, but also on the machine reliability analysis, the reliability as an evaluation index. From the point of view of reliability, the blind pursuit of complex structure is often not wise. Generally speaking, the system is more complex, then the system reliability is lower. In order to improve the reliability of complex systems, it is necessary to increase the parallel system, which will inevitably increase the cost of the machine. The environmental protection is also design must be carefully considered important aspects. Have a bad effect on the environment of the technical scheme, must detailed analysis, and puts forward the technical maturity of the solution. Through the evaluation, the final decision, according to determine a next step technology design of the schematic diagram or kinematic diagram of mechanism. In the program design phase, to correctly handle the relationship between reference and innovation. Similar machines ought to draw lessons from the successful precedent, originally weak and inconsistent with the current task demands of the part should be improved or changed. We should not only actively innovation, against conservative and copy the original design, but also against a novelty and reasonable original experience abandoned the two wrong tendencies. ( three) the technical design stage design goal was to generate assembly sketches and assembly sketches. The sketch design identified the components and parts of the form and basic size, including connections between components, spare, parts of the form and basic size. The final drawing parts drawing, parts and assembly drawings and assembly drawings. In order to determine the main parts of the basic size, must do the following:1) the kinematic design of machines. According to determine the structure scheme, determine the driver parameters ( power, speed, linear speed etc. ). Then do the kinematics calculation, thereby determining the motion components of movement parameters ( speed, velocity, acceleration ). 2) the machine dynamics calculation. Combined with the structure and motion parameters, calculation of the main part of the load size and characteristics. The calculated load, the part is designed, which is applied to parts of the nominal ( or nominal ) load. 3) parts of the working capability design. The known major parts by the nominal load size and characteristics, can be zero, parts of the preliminary design. The designs are based on the ability to work standards, should be zero, parts of the general failure situation, job characteristics, environmental conditions and reasonably develop, generally have the strength, stiffness, vibration, life criterion. Through calculation and comparison, then decided to spare, parts of the basic size. 4) assembly sketches and general assembly sketch design. According to the main components, the basic size, design a component assembly sketches and assembly sketches. The sketch of all parts of the shape and size of the structured design. In this step, need good coordination among the various parts of the structure and size, to consider a comprehensive design of zero, parts of the process of the structure, so that all the parts have the most reasonable configuration. 5) the main parts of the check. There are some parts, in the above third ) step due to the specific structure of undetermined, difficult to conduct detailed work capacity calculation, we can only do a preliminary calculation and design. In the draw assembly design and assembly sketches, all parts of the structure and size are known, the mutually abutting the relations between components also known as. Only then, can be more accurately determined action on the part of load, decisions affecting parts working ability detail factor. Only on this condition, it can and must be for something important or shape and stress condition of complex parts for accurate calculation of. According to the check results, repeatedly modify parts of the structure and size, until satisfied. In the technical design of the various steps in, nearly thirty or forty years with the development of the optimization design technology, more and more shows it can make the selection of structural parameters to achieve the best capacity. Some new numerical method, such as finite element method, can make previously difficult to quantitative calculation problems in obtaining excellent approximation calculation results. For a few very important, the structure is complex and expensive parts, where necessary, must use the model test method to the design, namely according to the preliminary design drawings to create a model, through the experiment, to find out the weak parts of the structure or the redundant section size, thus enhance or reduce the modification to the original design, finally achieving the perfect degree. Mechanical reliability theory for the technical design stage, according to the viewpoint of reliability design of zero, parts of structure and its parameters to make it meet the requirement of reliability evaluation, put forward the improvement design is proposed, which can further improve the quality of machine design. These new design methods and concepts, shall, should be applied in the design and promotion, make get corresponding development. Sketch design completed, according to the sketch has identified parts of basic size, design parts drawing. At this time, there are still a large number of parts structure details to be examined and determined. Design work plan, full consideration should be given to the processing of parts and assembly process, parts during machining process and processing after completion of the inspection requirements and implementation methods. Some details of the arrangement if the parts work ability was worth considering influence, must go back to check the work ability. Finally draw out in addition to the standard outside of all parts of the map. According to the final shape of the parts of the structure and size, to draw the part and assembly drawings and assembly drawings. Through this work, can check out the detail drawings may be hidden in the size and structural errors. People regard this work popularly called paper assembly. ( four) the preparation of technical documents phase technology file types, commonly used in the machine design brochures, manuals, and other standard parts list. Design calculation specification, should include the scheme selection and technical design all the conclusions of the content. Preparation for users of machine instructions, should introduce the users machine performance parameters, operation methods, daily maintenance and simple repair method, spare parts catalog. Other technical documents, such as inspection single, purchased parts list, acceptance, as needed and not be compiled. ( five) the computer application in mechanical design with the development of computer technology, the computer in the mechanical design has been increasingly widely used, and there have been many efficient design, analysis software. It can be used in the design phase of projects, can be of different includes large and complex project structural strength, stiffness and dynamic characteristics of precision analysis. At the same time, also in the computer to build virtual prototype, using virtual prototype simulation to verify the design, which realizes the design phase fully assess the feasibility of the design. Can say, the computer technology in machinery design promotion has already changed mechanical design process, it enhances the design quality and efficiency advantages is difficult to estimate. The above briefly introduced the machine design program. Broadly speaking, in the machine manufacture process, appear likely at any time due to technical reasons for modifying the design condition. If you want to modify, should follow certain procedures. Machine factory, should have planned to carry out investigation; in addition, users in the use of the process will also give the design or manufacture sector feedback problems. Design department according to these information, through the analysis, it is also possible for the original design was modified, even remodel. These work, although generalized also belong to design program components, but belongs to another level of problems, this book will not discuss its specific content. But as design worker, should have a strong sense of social responsibility, to my vision extends into the manufacture, use and waste utilization of total process, repeated constantly improve the design, in order to make the quality of the machine to continue to improve, to better meet the needs of production and life At the beginning of the design before, must make the design task. When the design task is more complex, using three general stages of design, the preliminary design, technical design and working drawing design; when the task is relatively simple, such as the simple mechanical model design, general machinery inherited design or variant design, it will start a design to achieve technical design depth, after review, modification and approval to do working drawing design, and become two stage design. In the three stage design in the preliminary design stage, design of the main steps of : determining the working principle and basic structure, motion design, main spare parts, drawing design, preliminary master plan, the preliminary design review. In the design phase, the main steps are: according to the review comments to modify the design, design of all parts, drawing the new general plan, technical design review. In working drawing design stage, according to the review comments to modify the design, draw all the working drawings and make all technical documents. For the mass or mass production of products, but also shape design. In the design of each step, may be found in the previous step some decided not reasonable, it need to fold back in front of that step, modify the irrational decisions, redo the subsequent design work. 1, making design task it is the preparatory work of the design. Design task is based on the user orders, the market needs and the new research results. Design departments application technology and market information, to be listed options, comparing its advantages and disadvantages, and business departments and users together, formulates the reasonable design target. The new design is particularly important. The goal of the task error will be caused serious damage to the economy, even with the overall failure. 2, determine the working principle and basic structure types such as de