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文獻綜述
論文題目 左支座零件制造工藝分析及夾具設計
(英 文)Design of process analysis and fixture manufacturing left bearing parts
學 院
專 業(yè)
姓 名 xxxxxxxx
學 號 xxxxxxxxxxxxx
指導教師
2014年3月20日
文獻綜述
1、 前言
機械加工工藝規(guī)程是規(guī)定產品或零部件機械加工工藝過程和操作方法等的工藝文件,是一切有關工生產人員都應嚴格執(zhí)行、認真貫徹的紀律性文件。生產規(guī)模的大小、工藝水平的高低以及解決各種工藝問題的方法和手段都要通過機械加工工藝規(guī)程來體現。而機床夾具是在機床上用以裝夾工件的一種裝置,其作用是使工件相對于機床或刀具有個正確的位置,并在加工過程中保持這個位置不變。它們的研究對機械工業(yè)有著很重要的意義。
機械的加工工藝及夾具設計是在完成了大學的全部課程之后,進行的一次理論聯系實際的綜合運用,使我對專業(yè)知識、技能有了進一步的提高,為以后從事專業(yè)技術的工作打下基礎。機械加工工藝是實現產品設計,保證產品質量、節(jié)約能源、降低成本的重要手段,是企業(yè)進行生產準備,計劃調度、加工操作、生產安全、技術檢測和健全勞動組織的重要依據,也是企業(yè)上品種、上質量、上水平,加速產品更新,提高經濟效益的技術保證。然而夾具又是制造系統(tǒng)的重要組成部分,不論是傳統(tǒng)制造,還是現代制造系統(tǒng),夾具都是十分重要的。因此,好的夾具設計可以提高產品勞動生產率,保證和提高加工精度,降低生產成本等,還可以擴大機床的使用范圍,從而使產品在保證精度的前提下提高效率、降低成本。當今激烈的市場競爭和企業(yè)信息化的要求,企業(yè)對夾具的設計及制造提出了更高的要求。
2、 發(fā)展歷史
從1949年以來,我國機械工業(yè)有了很大的發(fā)展,已經成為工業(yè)中產品門類比較齊全、具有相當規(guī)模和一定技術基礎的產業(yè)部門之一,其機械加工和夾具也有很大的發(fā)展,但是與工業(yè)發(fā)達國家相比,我們這方面的水平還存在著階段性的差距,主要表現在機械產品質量和水平不夠高,加工工藝過程不合理,夾具應用也比較少,使其加工工人勞動強度大,加工出來的產品也不理想。
夾具從產生到現在,大約可以分為三個階段:第一個階段主要表現在夾具與人的結合上,這是夾具主要是作為人的單純的輔助工具,是加工過程加速和趨于完善;第二階段,夾具成為人與機床之間的橋梁,夾具的機能發(fā)生變化,它主要用于工件的定位和夾,夾具與操作人員改進工作及機床性能的提高有著密切的關系,所以對夾具引起了重視;第三階段表現為夾具與機床的結合,夾具作為機床的一部分,成為機械加工緊。人們越來越認識到中不可缺少的工藝裝備。
3、 發(fā)展現狀
長期以來,加工工藝編制是由工藝人員憑經驗進行的。如果由幾位工藝員各自編制同一個零件的工藝規(guī)程,其方案一般各不相同,而且很可能都不是最佳方案。這是因為工藝設計涉及的因素多,因果關系錯綜復雜。CAPP將是機械加工工藝的發(fā)展趨勢,它不僅提高了工藝設計的質量,而且使工藝人員從繁瑣重復的工作中擺脫出來,集中精力去考慮提高工藝水平和產品質量問題。
制造業(yè)是國民經濟的基礎,隨著以計算機技術為主導的現代科學技術的迅速發(fā)展,以“時間驅動”為特征的市場競爭、產品更新換代的加快、商品需求的多樣化、用戶素質的提高等使制造業(yè)面臨著巨大的挑戰(zhàn),特別像后鋼板彈簧吊耳類不規(guī)則零件的加工就出現了一些問題,在現階段像后鋼板彈簧吊耳類的加工還沒達到現代自動化的水平。在現代的中小批量生產中,它的加工工藝還需人工畫線的方法來保證其精度,而對工件的裝夾也是通過人工的方法進行的。因此我國對后鋼板彈簧吊耳類不規(guī)則零件的加工還處于效率低、成本高的階段。
機床夾具最早出現在18世紀后期。隨著科學技術的不斷進步,夾具已從一種輔助工具發(fā)展成為門類齊全的工藝裝備。
國際生產研究協(xié)會的統(tǒng)計表明,目前中、小批多品種生產的工件品種已占工件種類總數的85%左右?,F代生產要求企業(yè)所制造的產品品種經常更新換代,以適應市場的需求與競爭。然而,一般企業(yè)都仍習慣于大量采用傳統(tǒng)的專用夾具,一般在具有中等生產能力的工廠里,約擁有數千甚至近萬套專用夾具;另一方面,在多品種生產的企業(yè)中,每隔3~4年就要更新50~80%左右專用夾具,而夾具的實際磨損量僅為10~20%左右。特別是近年來,數控機床、加工中心、成組技術、柔性制造系統(tǒng)(FMS)等新加工技術的應用,對機床夾具提出了如下新的要求:
1)能迅速而方便地裝備新產品的投產,以縮短生產準備周期,降低生產成本;
2)能裝夾一組具有相似性特征的工件;
3)能適用于精密加工的高精度機床夾具;
4)能適用于各種現代化制造技術的新型機床夾具;
5)采用以液壓站等為動力源的高效夾緊裝置,以進一步減輕勞動強度和提高勞動生產率;
6)提高機床夾具的標準化程度。
4、發(fā)展趨勢
隨著機械工業(yè)的迅速發(fā)展,對產品的品種和生產率提出了愈來愈高的要求,使多品種,中小批生產作為機械生產的主流,為了適應機械生產的這種發(fā)展趨勢,必然對機床夾具提出更高的要求。特別像后鋼板彈簧吊耳類不規(guī)則零件的加工還處于落后階段。在今后的發(fā)展過程中,應大力推廣使用組合夾具、半組合夾具、可調夾具,尤其是成組夾具。在機床技術向高速、高效、精密、復合、智能、環(huán)保方向發(fā)展的帶動下,夾具技術正朝著高精高效模塊組合通用經濟方向發(fā)展。
(1)特種加工 它是指一些物理的、化學的加工方法,如電火花加工、電解加工、超聲波加工、激光加工、離子束加工等。特種加工方法的主要對象是難加工材料的加工,如金剛石、陶瓷等超硬材料的加工,其加工精度可達分子級加工單位或原子級加工單位,所以它又常常是精密加工和超精密加工的重要手段。特種加工與傳統(tǒng)加工相結合的復合加工有較大的發(fā)展前途。
(2)快速成形 利用離散、堆積成形概念,可將一個三維實體分解為若干二維實體制造出來,再經堆積而構成三維實體。
(3)精密工程 它包括精密加工的超精密加工技術、微細加工和超微細加工技術、微型機械和納米技術等方面。當前,以納米技術為代表的超精密加工技術和以微細加工為手段的微型機械技術有重要意義,它們代表了這一時期精密工程的方向。
(4)傳統(tǒng)加工工藝的改造和革新 這一方面的技術潛力很大,如高速切削、超高速切削、強力磨削、超硬材料磨具的出現都對加工理論的發(fā)展、加工質量和效率的提高有重要意義。另一方面,舊設備的改造和挖潛,如普通機床改造成數控機床等,對機械工業(yè)的發(fā)展和提高是不容忽視的。
5、設計面臨的問題
在設計中,需要對零件加工工藝方案和夾具進行設計,在確定加工工藝方案時,可能會出現工藝路線的不合理,甚至出現不能保證加工所要求達到的精度。在進行夾具設計時,可能因定位基準選擇不合理,出現過定位或欠定位造成加工的零件的精度得不到保證。在選擇夾緊機構時由于機構的大小,尺寸等不合理,而達不到夾緊的目的,也可能因夾緊力作用點或作用面的位置不合理而使工件產生翻轉。所以在設計過程中應制訂多套方案,以供比較選擇最優(yōu),同時還要多請教指導老師和同學,并多查閱相關的書籍來盡可能好的完成設計。
6、總結
在機械制造中,為完成需要的加工工序、裝配工序及檢驗工序等,使用著大量的夾具。利用夾具,可以提高勞動生產率,提高加工精度,減少廢品,可以擴大機床的工藝范圍,改善操作的勞動條件。因此,夾具是機械制造中的一項重要的工藝裝備。夾具設計的基礎理論一個好的機床夾具,首先要保證能加工出合格的產品。為此,所設計的夾具首先應滿足以下兩項要求:第一,在未受外力作用時,加工件對刀具和機床應保持正確的位置,即加工件應有正確的定位。第二,在加工過程中,作用于加工件上的各種外力,不應當破壞加工件原有的正確定位,即對加工件應有正確的夾緊。
綜上,機械加工藝及夾具隨著科技的發(fā)展都使計算機技術、數控技術、控制論及系統(tǒng)工程與制造技術的結合為制造系統(tǒng),形成現代制造工程學。而物料流、能量流、信息流是組成制造系統(tǒng)的三個基本要素。現代加工都為集成化的系統(tǒng)加工,這雖減輕了工人的勞動強度,但同時對工人的知識水平要求較高。這需要我們全方位的認知現代科技知識。因此,在以后的學習中需要我們全方位的學習其各個相關領域的知識,不能只注重一點,為將來的人才戰(zhàn)略提出了新的要求。
參考文獻
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外文資料翻譯
Electromechanical integration technology and its application
An electromechanical integration technology development
Mechatronics is the machinery, micro-, control, aircraft, information processing, and other cross-disciplinary integration, and its development and progress depends on the progress of technology and development, the main direction of development of a digital, intelligent, modular, and human nature , miniaturization, integration, with source and green.
1.1 Digital
Microcontroller and the development of a number of mechanical and electrical products of the base, such as the continuous development of CNC machine tools and robots, and the rapid rise of the computer network for the digital design and manufacturing paved the way for, such as virtual design and computer integrated manufacturing. Digital request electromechanical integration software products with high reliability, easy operability, maintainability, self-diagnostic capabilities, and friendly man-machine interface. Digital will facilitate the realization of long-distance operation, diagnosis and repair.
Intelligent 1.2
Mechanical and electrical products that require a certain degree of intelligence, it is similar to the logical thinking, reasoning judgement, autonomous decision-making capabilities. For example, in the CNC machine increase interactive features, set up Intelligent I / O interface and intelligent database technology, will use, operation and maintenance of bring great convenience. With fuzzy control, neural network, gray, wavelet theory, chaos and bifurcation, such as artificial intelligence and technological progress and development and the development of mechanical and electrical integration technology has opened up a vast world.
Modular 1.3
As electromechanical integration products and manufacturers wide variety of research and development of a standard mechanical interface, dynamic interface, the environment interface modules electromechanical integration products is a complex and promising work. If the development is set to slow down. VVVF integrated motor drive unit with vision, image processing, identification and location of the motor functions, such as integrated control unit. Thus, in product development, design, we can use these standards modular unit quickly develop new products.
1.4 Network
As the popularity of the network, network-based remote control and monitoring of various technical ascendant. The remote control device itself is the integration of mechanical and electrical products, fieldbus technology to household appliances and LAN network possible, use a home network to connect various home appliances into a computer as the center of computer integrated appliances system, so that people in the home can be full enjoyment of the benefits of various high-tech, therefore, electromechanical integration products should be no doubt North Korea networks.
1.5 humanity
Electromechanical integration of the end-use product is targeted, how to give people electromechanical integration of intelligent products, emotion and humanity is becoming more and more important, electromechanical integration products in addition to improving performance, it also urged the color, shape and so on and environmental coordination, the use of these products, or for a person to enjoy, such as home robot is the highest state of human-machine integration.
1.6 miniaturization
Micro-fine processing technology is a necessity in the development, but also the need to improve efficiency. MEMS (Micro Electronic Mechanical Systems, or MEMS) refers to quantities can be produced by the micro-collection agencies, micro-sensors, micro actuators and signal processing and control circuit until interface, communication and power is one of the micro-devices or systems . Since 1986 the United States at Stanford University developed the first medical microprobe, 1988 at the University of California, Berkeley developed the first micro-motor, both at home and abroad in MEMS technology, materials and micro-mechanism much progress has been made, the development of all sorts MEMS devices and systems, such as the various micro-sensors (pressure sensors, micro-accelerometer, micro-tactile sensor), various micro-component (micro-film, micro-beam, microprobes, micro-link, micro-gear, micro-bearings, micro-pump , microcoil and micro-robot, etc.).
1.7 Integration
Integration includes a mutual penetration of various technologies, and integration of various products of different structural optimization and composite, and included in the production process at the same time processing, assembly, testing, management, and other processes. In order to achieve more variety, small batch production of automation and high efficiency, the system should have a more extensive flexible. First system can be divided into several levels, allowing the system to function dispersed, and security and coordination with other parts of the operation, and then through software and hardware at various levels will be organically linked to its optimal performance, the most powerful.
1.8 with source of
Electromechanical integration refers to the product itself with energy, such as solar cells, fuel cells and large-capacity battery. As on many occasions not be able to use electricity, which campaigns for the mechanical and electrical integration products, has a unique power source comes with the benefits. Sources with the integration of mechanical and electrical product development direction of.
Green 1.9
The development of technology in people's lives brought great changes in the material at the same time has also brought rich resources, deterioration of the ecological environment consequences. Therefore, people calling for the protection of the environment, regression, and achieving sustainable development in the concept of green products such calls have emerged. Green products is low-power, low-wood consumption, clean, comfortable, coordination and utilization of renewable products. In its design, manufacture, use and destruction of human beings should be in line with environmental protection and health requirements, electromechanical integration of green products is mainly refers to the use of time is not pollute the ecological environment, at the end of product life, and regeneration of decomposition products.
2 electromechanical integration in the application of technology in the iron and steel
In the iron and steel enterprises, the integration of mechanical and electrical systems are at the core microprocessor, the computer, industrial computer, data communications, display devices, meters and the combination of technologies such as organic, assembled by the merger means for the realization of a large-scale integrated system create conditions for effective integration, enhanced system control precision, quality and reliability. Electromechanical integration technology in the iron and steel enterprises in the mainly used in the following areas:
2.1 Intelligent Control Technology (IC)
As a large-scale iron and steel, high-speed continuous and the characteristics of the traditional control technologies encountered insurmountable difficulties, it is necessary to adopt very intelligent control technology. Control technologies include intelligent expert system, neural and fuzzy control, intelligent control techniques in steel product design, manufacturing, control, product quality and diagnostic equipment, and other aspects, such as blast furnace control system, electric furnace and continuous casting plant, steel rolling system , steelmaking - Casting integrated scheduling system - rolling, cold rolling, etc..
2.2 Distributed Control System (DCS)
Distributed control system uses a central command for the control of a number of Taiwan-site monitoring and intelligent computer control unit. Distributed control systems can be two, three or more levels. Using computers to concentrate on the production process monitoring, operation, management and decentralized control. With monitoring and control technologies, and the functions of distributed control system more and more. Not only can be achieved control of the production process, but also can be achieved online optimization, the production process real-time scheduling, production planning statistical management functions, as a measurement, control, integration of the integrated system. DCS control functions with diverse features and easy operation, the system can be extended, easy maintenance and high reliability characteristics. DCS is decentralized and centralized control monitoring, fault-minor, and the system has the chain protection features, the use of manual control system failure operational measures, the system is highly reliable. Distributed control system and centralized control system compared to their more functional, with a higher level of security. Is the large-scale integration of mechanical and electrical systems main trend.
2.3 Open Control System (OCS)
Open Control System (Open Control System) is the development of computer technology led by the new structure concept. "Open" means a standard for the exchange of information in order consensus and support this standard design systems, different manufacturers products can be compatible and interoperable, and the sharing of resources. Industrial control systems through open communication network so that all control equipment, management, computer interconnections, to achieve control and management, administration, integrated decision-making, through fieldbus to the scene and control room instrumentation control equipment interconnected to achieve integrated measurement and control of.
2.4 Computer Integrated Manufacturing System (CIMS)
CIMS is the iron and steel enterprises will be and the production and operation, production management and process control connecting to achieve from raw materials into the plant, production and processing of shipments to the entire production process and the overall integration process control. Currently iron and steel enterprises have basically achieved process automation, but this kind of "automated island" of single automation lack of information resources and the sharing of the unified management of the production process, can hardly meet the requirements of the iron and steel production. Future competition iron and steel enterprises is the focus of many varieties, small batch production, cheap and of good quality, timely delivery of goods. In order to improve productivity, saving energy, reducing staff and the existing inventory, accelerate cash flow, production, operation and management of the overall optimization, the key is to strengthen the management, access to the benefits of raising the competitiveness of businesses. The United States, Japan and some other large-scale iron and steel enterprises in the 1980s has been widely realization of CIMS.
2.5 Fieldbus Technology (FBT)
Fieldbus Technology (Fied Bus Technology) is the connection settings in the field of instrumentation installed in the control room and control devices for digital, bi-directional, multi-station communication link. Fieldbus technology used to replace the existing signal transmission technology (such as 4 to 20 mA, DC DC transmission), it will enable more information in the field of Intelligent Instrumentation devices and higher-level control system in the joint between the communications media on the two-way transmission. Fieldbus connection can be through save 66% or more on-site signal connecting wires. Fieldbus lead to the introduction of the reform and the new generation of DCS around open fieldbus automation system of instruments, such as intelligent transmitter, intelligent, fieldbus detection instruments, fieldbus of PLC (Programmable Logic Controller) local control stations and field development.
2.6 AC drive technology
Transmission technology in the iron and steel industry plays a crucial role. With power technology and the development of microelectronics technology, the development of AC variable speed very quickly. The AC drive to the advantages of electric drive technology in the near future from AC drive completely replace DC transmission, the development of digital technology, complex vector control technologies to achieve practical, AC variable speed system speed and performance has reached more than DC converter level. Now whether small or large-capacity electrical motor capacity synchronous motor can be used to achieve reversible induction motor or smoothing governor. AC drive system in the production of steel rolling emerged as a welcome users, applications continues to expand.
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