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1 英文文獻翻譯
1.1 On the CNC Turning Process Analysis
First, the contents of the CNC Turning Process
??CNC Turning process is used when the CNC lathe parts used methods and techniques combined. Its main contents include the following aspects:
? (A) Select and identify parts of the CNC Turning content; (b) the part drawings CNC Turning Process Analysis; (3) tool, fixture selection and adjustment of design; (d) processes, working step design; (e) processing trajectory calculation and optimization; (vi) the preparation of CNC turning processing, verification and modification; (7) the first piece of test processing and on-site treatment of the issue; (8) the preparation of CNC machining technology documents; In short, the contents of CNC machining process more, and some similarities with ordinary machining.
??Second, CNC Turning Process Analysis
? Process analysis is the early stage of CNC turning process preparations. Process of making a very reasonable or not, the program's establishment, machine processing efficiency and processing precision parts have a significant impact. In order to prepare a reasonable and practical processing procedure that requires the programmer, not only to understand the working principle of CNC lathe, performance characteristics and structure. Master programming languages and programming formats, but also proficiency in workpiece machining process, determine a reasonable cutting parameters, and correctly use tools and workpiece clamping methods. Therefore, the process should follow the general principles of combining the characteristics of CNC lathes, serious and detailed process analysis for NC turning. Its main contents are: According to the drawings analysis of parts machining requirements and reasonable; determining the workpiece on CNC lathe setup mode; the surface of the processing sequence, tool feed lines, as well as tools, fixtures and cutting parameters selection, etc. .
???(A) Part Diagram Analysis
???Parts diagram analysis is to develop CNC turning process priority. Mainly for dimensioning method of analysis, factor analysis and profile geometry precision and technical requirements analysis. In addition, the structure should also analyze the components and processing requirements are reasonable, selection process benchmarks.
???1. Dimension Analysis
?? Part drawing on the dimensioning methods should adapt to CNC lathe processing features to mark the same size of the base coordinates given size or directly. This labeling method is not only easy to program, and it helps the design basis, process benchmarking, measuring baseline and programming the unity of origin. If the components of the direction of the size of the map there is no uniform design basis could be considered without affecting the accuracy of the premise part of the process to select a single benchmark. Calculation into the various sizes, to simplify the programming calculations.
???2. Profile geometry factor analysis
???In the manual programming, to calculate the coordinates of each node. In the auto-programming the part when all the contours of the definition of geometric elements. Therefore, in part drawing analysis, to analyze the geometric elements of the given condition is sufficient.
???3. Analysis of accuracy and technical requirements
?? The accuracy of parts being processed and technical analysis, is part of an important process analysis, only the analysis of parts dimensional accuracy and surface roughness, based on rational choice in order to correctly processing methods, clamping methods, cutting tools and cutting parameters and so on. The main contents include: analysis of accuracy and the various technical requirements are complete, whether it is reasonable; analyze the processes of CNC turning machining accuracy can meet drawing requirements, if not reach, allowing up to take other processing methods, the process should be given to the follow-up left margin; pairs of drawings on the surface of location accuracy requirements shall be guaranteed to complete in one setup; to require a higher surface roughness of the surface should be constant linear speed cutting (Note: In the face turning when the spindle should be limited The maximum speed).
??(B) the choice of fixtures and tools
?? 1. Workpiece fixturing and positioning
?? CNC turning operations as possible after a setup can be processed into all or most of the generation of machined surface, minimizing setup times in order to improve processing efficiency, and ensure precision. For shaft parts, usually in their cylindrical parts cylinder for positioning the base; for the sleeve parts, then the hole is positioned within the base. CNC lathe fixture in addition to using generic auto-centering three-jaw chuck, 4 Jaw chuck, hydraulic, electric and pneumatic clamps, there are a variety of universal good dedicated fixture. The actual operation should be a reasonable choice.
???2. Tool Selection
?? In addition to the life of cutting tools and tool materials, related to, but also the diameter of the tool a great relationship. Larger tool diameter, can withstand the greater the amount of cutting. So in part the shape permitting use of the tool diameter as large as possible is to extend tool life, increased productivity and effective measures. NC turning tool commonly used in general be divided into three categories. Namely, acuminate turning tool, arc-shaped turning tools and forming turning tools. Reposted elsewhere in the paper for free download http://www.hi138.com
(1)acuminate Cutters. A straight line-shaped cutting edge is characterized by generally known as acuminate Tool Tool. Its tip by a straight line of the main, the Deputy cutting edge composition, such as the cylindrical side knives, end-turning tools, etc.. Such turning tools when machining parts, spare parts outline the main shape of the tip by an independent or a linear displacement obtained after the main cutting edge.
?? (2) The arc-shaped lathe tool. Apart from turning circle inside and outside the surface of things, especially suitable for turning all kinds of connections forming smooth surfaces. It is characterized by: constitute the main cutting edge of the blade shape of a contour line of roundness error or error of a small arc, the arc of each blade is arc-shaped lathe tool bit tip, it is not a round cutter sites arc, while at the center of the arc.
?? (3) forming Tool. Namely, the contours of parts being processed entirely by the shape of turning tool blade shape and size decisions. CNC turning, the lathe tool commonly used in forming a small radius arc turning tool, car slot knife and thread turning tools and so on. In order to reduce tool change time and convenience of the knife is easy to realize the standardization of mechanical processing. CNC turning, we should maximize the use of machine-type Cutters Indexable.
?? (C) Cutting Select
?? CNC Turning back the cutting parameters, including a knife to eat the amount of ap, spindle speed S (or the cutting speed and the feed rate F (or the feed f).
?? Cutting parameters selection principle, a reasonable selection of cutting parameters for improving the quality of critical CNC lathe processing. CNC lathe cutting parameters to determine when the machine instructions must be in accordance with the requirements, as well as the durability of the tool to choose, but also with practical experience of using analogy to determine. The choice of the general principle is: rough car, first of all consider the case of machine tool stiffness to allow the greatest possible choice knife back to eat the amount of ap; followed by a larger feed choice f; last longer permitted under the tool to determine an appropriate life The cutting speed Increased back to eat away a knife blade can reduce the amount of times, improve processing efficiency, increasing the feed rate is conducive to chip breaking. Fine car, should focus on considering how to ensure processing quality, and on this basis, to maximize processing efficiency, it should choose a smaller knife to eat the amount of back and feed rate, as much as possible to improve processing speed. Spindle speed S (r / min) according to cutting speed (mm / min) by the formula (D for the workpiece or cutter / a diameter of mm) is calculated, you can also determine the look-up table or according to practical experience.
?? (D) The division processes and the development process in order
?? 1. The principle of separation processes
???In the CNC lathe machining parts, the division of the principle of common processes in two ways.
?? (1) Maintain the principle of accuracy. Processes generally require as much as possible concentrated, thick, finishing usually completed in one setup. To reduce the thermal deformation and cutting force deformation on the workpiece shape, position accuracy, dimensional accuracy and surface roughness effects, they should be rough, finishing separately.
?? (2) improve production efficiency principle. In order to reduce tool changing times, save tool change time, improve production efficiency, should need to use the same knife for processing after the processing of parts have been completed, and back to another to process other parts of the knife, while air travel should be minimized.
?? 2. Determine the processing sequence
???Develop processing sequence followed in general the following principles:
?? (1) fine after the first rough. In accordance with Rough fine cars fine car and a half order, gradually increase the machining accuracy.
?? (2) The first, after nearly far. Away from the point of the knife near the site of the first processing, far away from the location of the knife-point after the processing, in order to shorten the distance of tool movement, reduce air travel time. In addition, the first long last, after turning blanks are conducive to maintaining a rigid or semi-finished products, to improve their cutting conditions.
?? (3) internal and external cross. On the inner surface and outer surface of both processing components required should conduct internal and external surface of the rough, after internal and external surface finish.
?? (4) basal plane first. Used as a fine should be given priority processing of the surface of the base out, positioning the surface of the base the more accurate the smaller the setup error.
?? 3 Conclusion
?? CNC machine tools as a high-efficiency equipment, people wishing to give full play to its high-performance, high-precision and high automation features, in addition to master the performance of machine tools, characteristics and operation methods, but also in the programming process to conduct a detailed analysis of pre - and determine a reasonable processing technology in order to get the best processing program.
1.2 中文翻譯
一、數控車削加工工藝是采用數控車床加數控車削加工工藝的內容??
工零件時所運用的方法和技術手段的總和。其主要內容包括以下幾個方面:??
(一)選擇并確定零件的數控車削加工內容;(二)對零件圖紙進行數控車削加工工藝分析;(三)工具、夾具的選擇和調整設計;(四)工序、工步的設計;(五)加工軌跡的計算和優(yōu)化;(六)數控車削加工程序的編寫、校驗與修改;(七)首件試加工與現場問題的處理;(八)編制數控加工工藝技術文件;總之,數控加工工藝內容較多,有些與普通機床加工相似。??
?二、數控車削加工工藝分析??
工藝分析是數控車削加工的前期工藝準備工作。工藝制定得合理與否,對程序的編制、機床的加工效率和零件的加工精度都有重要影響。為了編制出一個合理的、實用的加工程序,要求編程者不僅要了解數控車床的工作原理、性能特點及結構。掌握編程語言及編程格式,還應熟練掌握工件加工工藝,確定合理的切削用量、正確地選用刀具和工件裝夾方法。因此,應遵循一般的工藝原則并結合數控車床的特點,認真而詳細地進行數控車削加工工藝分析。其主要內容有:根據圖紙分析零件的加工要求及其合理性;確定工件在數控車床上的裝夾方式;各表面的加工順序、刀具的進給路線以及刀具、夾具和切削用量的選擇等。??
?。ㄒ唬┝慵D分析??
零件圖分析是制定數控車削工藝的首要任務。主要進行尺寸標注方法分析、輪廓幾何要素分析以及精度和技術要求分析。此外還應分析零件結構和加工要求的合理性,選擇工藝基準。??
1.尺寸標注方法分析??
零件圖上的尺寸標注方法應適應數控車床的加工特點,以同一基準標注尺寸或直接給出坐標尺寸。這種標注方法既便于編程,又有利于設計基準、工藝基準、測量基準和編程原點的統一。如果零件圖上各方向的尺寸沒有統一的設計基準,可考慮在不影響零件精度的前提下選擇統一的工藝基準。計算轉化各尺寸,以簡化編程計算。??
2.輪廓幾何要素分析??
在手工編程時,要計算每個節(jié)點坐標。在自動編程時要對零件輪廓的所有幾何元素進行定義。因此在零件圖分析時,要分析幾何元素的給定條件是否充分。??
3.精度和技術要求分析??
對被加工零件的精度和技術進行分析,是零件工藝性分析的重要內容,只有在分析零件尺寸精度和表面粗糙度的基礎上,才能正確合理地選擇加工方法、裝夾方式、刀具及切削用量等。其主要內容包括:分析精度及各項技術要求是否齊全、是否合理;分析本工序的數控車削加工精度能否達到圖紙要求,若達不到,允許采取其他加工方式彌補時,應給后續(xù)工序留有余量;對圖紙上有位置精度要求的表面,應保證在一次裝夾下完成;對表面粗糙度要求較高的表面,應采用恒線速度切削(注意:在車削端面時,應限制主軸最高轉速)。?
?。ǘA具和刀具的選擇??
1.工件的裝夾與定位??
數控車削加工中盡可能做到一次裝夾后能加工出全部或大部分代加工表面,盡量減少裝夾次數,以提高加工效率、保證加工精度。對于軸類零件,通常以零件自身的外圓柱面作定位基準;對于套類零件,則以內孔為定位基準。數控車床夾具除了使用通用的三爪自動定心卡盤、四爪卡盤、液壓、電動及氣動夾具外,還有多種通用性較好的專用夾具。實際操作時應合理選擇?。??
2.刀具選擇??
刀具的使用壽命除與刀具材料相關外,還與刀具的直徑有很大的關系。刀具直徑越大,能承受的切削用量也越大。所以在零件形狀允許的情況下,采用盡可能大的刀具直徑是延長刀具壽命,提高生產率的有效措施。數控車削常用的刀具一般分為3類。即尖形車刀、圓弧形車刀和成型車刀。??
?。?)尖形車刀。以直線形切削刃為特征的車刀一般稱為尖形車刀。其刀尖由直線性的主、副切削刃構成,如外圓偏刀、端面車刀等。這類車刀加工零件時,零件的輪廓形狀主要由一個獨立的刀尖或一條直線形主切削刃位移后得到。??
?。?)圓弧形車刀。除可車削內外圓表面外,特別適宜于車削各種光滑連接的成型面。其特征為:構成主切削刃的刀刃形狀為一?圓度誤差或線輪廓誤差很小的圓弧,該圓弧刃的每一點都是圓弧形車刀的刀尖,因此刀位點不在圓弧上,而在該圓弧的圓心上。??
(3)成型車刀。即所加工零件的輪廓形狀完全由車刀刀刃的形狀和尺寸決定。數控車削加工中,常用的成型車刀有小半徑圓弧車刀、車槽刀和螺紋車刀等。為了減少換刀時間和方便對刀,便于實現機械加工的標準化。數控車削加工中,應盡量采用機夾可轉位式車刀。??
?。ㄈ┣邢饔昧窟x擇??
數控車削加工中的切削用量包括背吃刀量ap、主軸轉速S(或切削速度υ)及進給速度F(或進給量f?)。??
切削用量的選擇原則,合理選用切削用量對提高數控車床的加工質量至關重要。確定數控車床的切削用量時一定要根據機床說明書中規(guī)定的要求,以及刀具的耐用度去選擇,也可結合實際經驗采用類比法來確定。一般的選擇原則是:粗車時,首先考慮在機床剛度允許的情況下選擇盡可能大的背吃刀量ap;其次選擇較大的進給量f;最后再根據刀具允許的壽命確定一個合適的切削速度υ。增大背吃刀量可減少走刀次數,提高加工效率,增大進給量有利于斷屑。精車時,應著重考慮如何保證加工質量,并在此基礎上盡量提高加工效率,因此宜選用較小的背吃刀量和進給量,盡可能地提高加工速度。主軸轉速S(r/min?)可根據切削速度υ(mm/min)由公式?S=υ1000/πD(D為工件或刀/具直徑?mm)計算得出,也可以查表或根據實踐經驗確定。??
?。ㄋ模﹦澐止ば蚣皵M定加工順序??
1.工序劃分的原則??
在數控車床上加工零件,常用的工序的劃分原則有兩種。??
?。?)保持精度原則。工序一般要求盡可能地集中,粗、精加工通常會在一次裝夾中全部完成。?為減少熱變形和切削力變形對工件的形狀、位置精度、尺寸精度和表面粗糙度的影響,則應將粗、精加工分開進行。??
?。?)提高生產效率原則。為減少換刀次數,節(jié)省換刀時間,提高生產效率,應將需要用同一把刀加工的加工部位都完成后,再換另一把刀來加工其他部位,同時應盡量減少空行程。??
2.確定加工順序??
制定加工順序一般遵循下列原則?:??
(1)先粗后精。按照粗車半精車精車的順序進行,逐步提高加工精度。??
?。?)先近后遠。離對刀點近的部位先加工,離對刀點遠的部位后加工,以便縮短刀具移動距離,減少空行程時間。此外,先近后遠車削還有利于保持坯件或半成品的剛性,改善其切削條件。??
?。?)內外交叉。對既有內表面又有外表面需加工的零件,應先進行內外表面的粗加工,后進行內外表面的精加工。??
?。?)基面先行。用作精基準的表面應優(yōu)先加工出來,定位基準的表面越精確,裝夾誤差越小。??
三、結?語??
數控機床作為一種高效率的設備,欲充分發(fā)揮其高性能、高精度和高自動化的特點,除了必須掌握機床的性能、特點及操作方法外,還應在編程前進行詳細的工藝分析和確定合理的加工工藝,以得到最優(yōu)的加工方案。
2 專業(yè)閱讀書目
2.1 機械制造基礎
內容摘要:
全書分上下二篇共二十章,上篇主要內容有鑄造、鍛壓、焊接、切削加工基礎知識,車、銑、刨、磨削加工,鉆削與鏜削加工,光整、特種加工和微機數控車床,鉗工共十一章。下盤主要內容有工程材料,金屬材料的改性工藝基礎,熱加工工藝基礎,毛坯的選用,金屬切削加工工藝基礎,典型表面的加工方法分析,機械零件的制造工藝過程及其技術經濟分析,機械制造自動化概論,質量、安全和環(huán)境保護共九章。(宋昭祥.機械制造基礎[M].北京:機械工業(yè)出版社,1998.)
2.2 液壓與氣壓傳動
內容摘要:
本書分液壓傳動和氣壓傳動兩篇。液壓傳動的主要內容有液壓傳動的基礎知識、液壓元件、液壓基本回路、典型液壓傳動系統、液壓伺服和電液比例控制技術及液壓傳動系統設計。氣壓傳動主要內容有氣壓傳動的基本知識。氣源裝置、氣動元件、氣動回路以及氣動程序控制系統的設計方法。(左建民.液壓與氣壓傳動[M].北京:機械工業(yè)出版社,2002.)
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