University life is coming to an end, and college students begin to do graduation projects. Before we do the graduation project, we should write a good opening report. So what is an excellent opening report? The following is the report of sleeve processing and mold opening that I compiled for you, for reference only. Let's have a look.
Student name
Professional mechanical design, manufacturing and automation
Instruct teachers to evaluate teachers.
Completion date: 202 1 Feb. 15.
Process analysis and fixture design of sleeve
Student: Wu Xingang
Instructor: Zhang
Teaching unit: College of Machinery and Materials, Three Gorges University
1 topic source
This topic comes from production practice and discusses the general basic problems in machining. This subject involves a wide range of knowledge and requires high design, which is a good exercise for students' design ability, especially their thinking ability. The research contents of the discipline include mechanics, materials science, mechanical principle, mechanical design, tolerance and interchangeability, mechanical manufacturing technology and other knowledge, especially the application and innovation of institutions are the main highlights of this discipline. Let students get a comprehensive exercise. The discipline requires students to have strong system design ability and innovation ability, which is a challenge for students. This subject is a typical mechanical design subject, which involves comprehensive mechanical knowledge and is closely combined with the direction of mechanical specialty.
2 the purpose and significance of the study
2. 1 the purpose of the study
With the rapid development of the world economy and science and technology, the market is constantly internationalized and globalized, and the competition in all walks of life is becoming increasingly fierce. If enterprises want to survive and develop in the cruel competition, they must strive to improve their competitiveness. Shorten the research and development time of new products, improve the design quality of products, reduce the research and development cost, and carry out innovative design. Only in this way can we meet the changing needs of the market.
In the mechanical production of modern enterprises, how to ensure the processing quality of parts, improve production efficiency and reduce production costs is the goal that enterprises constantly pursue. With the increasingly fierce market competition, higher requirements are put forward for the technical economy of mechanical parts, and good technical economy largely depends on the formulation of processing technology. Sleeve parts are the most common parts in mechanical products, and their production technology is quite special. The improved sleeve part can achieve higher precision, and the fixture is simple in structure, convenient and quick to operate, and can be reused, thus greatly reducing the cost.
2.2 the significance of the study
The process planning of parts plays a very important role in machining, and whether the process planning of parts is reasonable or not is directly related to whether the parts can finally meet the quality requirements. The design of fixture is also an essential part, which is related to whether it can improve its processing efficiency. Therefore, these two are crucial links in the machining industry.
Machining technology refers to the whole process of changing the shape, size, relative position and performance of blank by machining method, making it a part.
The basic unit of machining process is working procedure, which consists of installation, station, working step and feed.
A process document that specifies the manufacturing process and operation method of a product or part is called a process specification. The main functions of the processing procedure are as follows:
1. Processing technology specification is the main basis for production preparation. According to its introduction, it is used to organize the supply of raw materials and blanks, adjust machine tools, design and manufacture special process equipment, prepare production operation plans, allocate labor force and conduct production cost accounting.
2. Processing technology specification is also the basis of organizing production and scheduling. With it, you can specify the progress and achieve high quality, high yield and low consumption.
3. The processing procedure is the basic technical document of the newly-built factory. According to it and the production procedure, the type and quantity of machine tools needed, the area of the factory, the plane layout of machine tools and the arrangement of various departments can be determined. Processing technology card and processing technology card are two main process documents. The inspection process includes inspection process cards, processes completed by automatic and semi-automatic machine tools and machine tool adjustment cards. Machining process card is a process document that explains the machining process of parts. Processing technology card is a part used to directly guide production, mass production and important parts in mass production when formulating each working procedure.
When machining a workpiece on a machine tool, in order to ensure the machining accuracy, the workpiece must be correctly installed to occupy the correct position for the cutting and forming movement of the machine tool and the cutter, and it must also be "positioned". In order not to be damaged by external forces such as cutting force, inertia force and gravity, a certain clamping force must be applied to the workpiece. This process is called "clamping". The whole process of positioning and clamping is called "installation". The important process equipment used to complete the task of workpiece installation on the machine tool is the most widely used "machine tool fixture" among all kinds of fixtures.
There are many kinds of machine tool fixtures, among which the most widely used universal fixture has standardized specifications and dimensions and is produced by professional factories. However, the special fixture which is widely used in mass production and specially serves a certain workpiece processing procedure needs to be designed and manufactured by various manufacturers according to the workpiece processing technology. Therefore, the design of special fixture is an important production preparation, and every fixture designer engaged in machining technology should master the basic knowledge of fixture design.
The sleeve part is a common part. Studying the processing technology and fixture production technology of sleeve parts can improve the production method of sleeve parts, improve the production efficiency of factories, reduce the production cost and improve the accuracy of parts, which is of great significance to actual production.
3 Research status and development trend at home and abroad
3. 1 Research status at home and abroad
The processing technology of sleeve parts varies with its function, structural shape, material, heat treatment and size. According to its structural form, it can be divided into two categories: short sleeve and long sleeve. In the process of machining, their clamping methods and machining methods are very different.
1) Function and structural characteristics of sleeve parts
Sleeve parts usually play a supporting or guiding role in products. Because of their different functions, there are great differences in structure and size, but they still have the same characteristics in structure: the main surfaces of the parts are internal and external rotating surfaces with high coaxiality requirements, and the walls of the parts are thin and easy to deform under stress. Its main technical requirements are: the accuracy of cylindrical surface diameter, usually 7 ~ 8; The accuracy of the inner hole diameter is usually the coaxiality of the inner and outer circles of IT7; Verticality between hole axis and end face and surface roughness, etc.
2) Production and processing conditions
Because of the thin wall of sleeve parts, it is easy to deform under radial force. In order to solve these problems, the following two clamping methods are often used:
(1) Positioning and clamping with external circle;
(2) Positioning with the processed inner hole. In the production process, uniform radial force clamping or axial force clamping is generally adopted. Commonly used clamps include soft claws, mandrels, spring collets, liquid-plastic clamps and so on. These fixtures are specially designed according to different sleeve parts. Once the structure and size of parts are changed or discontinued, these fixtures will become scrapped products, causing great waste and increasing production costs, which enterprises should try to avoid.
Main technical problems in processing sleeve parts;
The main problems in the processing of general sleeve parts are to ensure the mutual position accuracy of the inner and outer circles (that is, to ensure the coaxiality of the surfaces of the inner and outer circles and the verticality between the axis and the end face) and to prevent deformation.
1) to ensure mutual position accuracy.
In order to ensure the coaxiality of the inner and outer circular surfaces and the verticality between the axis and the end surface, the following three technological schemes can usually be adopted: (1) Install and process the inner and outer circular surfaces and the end surface at one time. (2) All processing is carried out in several devices. Firstly, the hole is machined, and then the cylindrical surface is machined based on the hole. (3) All construction works shall be carried out in several installations. Firstly, the excircle is processed, and then the inner hole is processed according to the surface of the excircle.
2) methods to prevent deformation
In the process of machining thin-walled sleeve, due to the influence of clamping force, cutting force and cutting heat, deformation often occurs, which leads to the decline of machining accuracy. Thin-walled sleeves that need heat treatment will also cause irreparable deformation if the heat treatment process is not properly arranged. In order to prevent the deformation of thin-walled sleeve, the following measures can be taken:
(1) Reduce the influence of clamping force on deformation;
(2) reducing the influence of cutting force on deformation;
(3) Reduce the error caused by thermal deformation.
3.2 Future development trend
4, the future development trend of processing technology:
1. Optimize process design by simulation technology.
Forming, modification and machining are the main processes of mechanical manufacturing technology, and they are the processes of manufacturing raw materials (mainly metal materials) into blanks or parts. These technological processes, especially hot working processes, are extremely complicated high-temperature, dynamic and instantaneous processes, during which a series of complex physical, chemical and metallurgical changes will occur. Not only can these changes not be directly observed, but indirect testing is also very difficult. Therefore, for many years, the design of hot working process can only rely on "experience". In recent years, the simulation and optimization design technology of hot working process formed by computer technology and modern testing technology has swept the world and become the hottest research hotspot and cross-century technical frontier of hot working disciplines.
The technological process of hot working (casting, forging, welding, heat treatment, injection molding, etc.) is simulated by using simulation technology. ) can be displayed virtually, and the process results (organization, performance and quality) can be predicted. By comparing different parameters, the process design can be optimized to ensure the success of one-time manufacturing of large parts. Ensure that a batch of parts are successfully tested at one time. Simulation technology has also been applied to machining, special machining and assembly process, and developed towards virtual manufacturing, which has become the technical basis of decentralized networked manufacturing, digital manufacturing and manufacturing globalization.
2. The forming accuracy is developing towards zero margin. The forming of blanks and parts is the first process of mechanical manufacturing. Metal blanks and parts are usually formed by casting, forging, stamping, welding and rolling. With the development of blank precision forming technology, the shape and dimensional accuracy of part forming is developing from near-net forming to net forming, that is, near-no-allowance forming. The boundary between "blank" and "part" is getting smaller and smaller. Some blanks are close to or reach the final shape and size of parts after forming, and can be assembled after grinding. The main methods include various forms of precision casting, precision forging, precision stamping, cold and warm extrusion, precision welding and cutting. For example, in automobile production, "agile precision stamping system close to zero margin" and "intelligent resistance welding system" are all under development.
3. Molding quality is developing towards almost no "defects". Another index of blank and parts forming quality is the number, size and harm degree of defects. Because the hot working process is very complicated and the factors are changeable, it is difficult to avoid defects. In recent years, the hot working field has put forward the goal of "developing in the direction of almost no" defects ",which refers to the concept of critical defects that will not cause early failure. The main measures taken are: (1) using advanced technology to purify metal melt, increase alloy structure density, and lay the foundation for obtaining intact castings and forgings; Adopting simulation technology, optimizing process design, realizing one-time molding and die trial success; Strengthen process monitoring and nondestructive testing, and find out the parts exceeding the standard in time; Through the research and evaluation of the safety and reliability of parts, the critical defect value is determined.
4. Machining is developing towards ultra-precision and ultra-high speed. At present, ultra-precision machining technology has entered the era of nano-machining, with machining accuracy of 0.025μm and surface roughness of 0.0045 μ m. Finishing technology is approaching from the current red band to the visible band or invisible ultraviolet and X-ray band. Ultra-finishing machine tools are developing in the direction of multi-function modularization; Superfinishing materials have expanded from metals to nonmetals.
5. The future development trend of fixture design;
Fixture is an indispensable part of machining. Driven by the development of machine tool technology in the direction of high speed, high efficiency, precision, compounding, intelligence and environmental protection, fixture and chuck technology are developing in the direction of high precision, high efficiency, modularization, combination, universality and economy.
(1) high accuracy
With the improvement of machining accuracy of machine tools, in order to reduce positioning error and improve machining accuracy, the manufacturing accuracy of chuck is required to be higher. The spacing accuracy of positioning holes of high-precision chuck reaches 5 microns, the verticality of fixture supporting surface reaches 0.0 1mm/300mm, and the parallelism reaches 0.0 1mm/500mm. The 4m long and 2m wide hole series combined welding chuck platform manufactured by demmeler company in Germany has a height error of 0.03mm, and the parallelism and verticality of precision flat-nose pliers are within 5μm; The positioning accuracy of repeated installation fixture is as high as 5 microns; The repeated positioning accuracy of the chuck is as high as 2 ~ 5 microns [12]. The accuracy of machine tool chuck has been improved to micron level, and the world-famous chuck manufacturing companies are all precision machinery manufacturing enterprises. It is true that in order to meet the needs and economy of different industries, chucks have different models and different levels of accuracy standards to choose from.
(2) High efficiency
In order to improve the production efficiency of machine tools, there are more and more double-sided, four-sided and multi-piece clamping fixture chuck products.
In order to reduce the installation time of the workpiece, all kinds of automatic centering clamping, precision flat pliers, lever clamping, cam clamping, pneumatic and hydraulic clamping, etc. And quick clamping function parts are continuously pushed out. It takes only 1 ~ 2 seconds to clamp and loosen the workpiece with a new type of electric control permanent magnet sucker, and the fixture structure is simplified, which creates conditions for multi-station, multi-face and multi-piece machining of machine tools. In order to shorten the time for installing and adjusting the fixture on the machine tool, the Swedish 3R fixture only needs 1 minute to complete the installation and adjustment of the WEDM machine tool chuck. Jergens's ball lock clamping system can position and lock the chuck on the machine tool table within 1 min. The ball lock clamping system can be used to replace the chuck on the flexible production line, which can shorten the downtime and improve the production efficiency.
(3) Modules and combinations
Modularization of fixture assembly is the basis of realizing combination. It has become the basic point of fixture technology development to adopt modular design to serialize and standardize fixture parts and quickly assemble various fixtures. Labor-saving, time-saving, material-saving and energy-saving are embodied in the innovation of various advanced fixture systems. Modular design lays a foundation for computer-aided design and assembly of fixture. Using CAD technology, parts library, typical fixture library, standard and user file library can be established to optimize fixture design and assembly fixture for users' three-dimensional entities [13]. Simulating the cutting process of tools can not only provide users with correct and reasonable matching schemes for fixtures and parts, but also accumulate experience, understand the market demand and constantly improve and perfect the fixture system. In cooperation with Huazhong University of Science and Technology, Modular Fixture Sub-branch is establishing a fixture professional technical website to provide a public platform for information exchange, fixture product consultation and development, and strive to realize the generalization, remote informationization and e-commerce of fixture design and service.
(4) universality and economy
The universality of fixture directly affects its economy. Modular combined fixture system has a large one-time investment. Only the fixture system has strong reconfigurability, reconfigurability and expansibility, wide application range, good universality, high fixture utilization rate and fast investment recovery can it show good economy. The hole series combined welding fixture of demmeler company in Germany can be assembled into various welding fixtures with only a few kinds and specifications of supporting components [14]. The powerful function of components makes the fixture universal, with fewer but more precise components, low matching cost and economical and practical popularization and application. Experts suggest that the combined fixture industry should strengthen cooperation with Industry-University-Research, speed up the pace of upgrading fixture technology with high technology, create a fixture professional technology website, make full use of modern information and network technology, and keep pace with the times to innovate and develop fixture technology. It is an effective way for China's modular fixture industry to actively contact foreign fixture manufacturers, strive for joint venture and cooperation, and introduce technology.
6. Main contents of the study.
The main content of this study is to design the processing program of sleeve parts through the process analysis of sleeve parts, including determining the manufacturing form of blanks, selecting benchmarks and determining the process route. In addition, the corresponding fixture should be designed.
7. Main stages, progress and requirements of the project
8, the ultimate goal and completion time
The ultimate goal of this project is to analyze the processing technology of sleeve parts, design their processing technology cards and processing technology cards, and complete the design of corresponding fixtures to meet the auditing standards of the auditing unit.
The final completion time is early June, and I will take part in the defense.
9. Existing conditions and necessary measures
The existing conditions are related professional courses learned during the university, related papers collected from the Internet, and corresponding drawing software. At present, we still need to collect more information, review the relevant knowledge we have learned and read more relevant documents in order to have a deeper understanding of the subject.
10, assisting units and main problems to be solved
In order to solve practical problems in production, this topic needs the strong support and help of teachers and classmates because of lack of experience.
refer to
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[1 1] Hu Zongwu. Non-standard mechanical equipment design manual [M]. Beijing: Machinery Industry Press, 2003.
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