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1.新建零件圖.
如下圖：
2.選擇需要作圖的平面進(jìn)入草繪界面
如下圖：
3. 分析此零件發(fā)現(xiàn)該零件為非對稱結(jié)構(gòu)，所以需要將其拆分成若干圖塊分別繪制，首先繪制零件的底部圓柱體。
如下圖：
4.草繪完成后進(jìn)行拉伸完成圓柱體
如下圖：
5. 上步完成后選擇圓柱體的一平面為基準(zhǔn)面進(jìn)入繪制地盤圓柱體四周的小突起
如下圖：
6.草繪后完成拉伸
如下圖：
7.選擇上步的草繪的基準(zhǔn)面草繪圓
如下圖：
8.拉伸切除后得到如圖四個通孔
如下圖：
9.選擇上步草繪的基準(zhǔn)平面草繪四個圓
如下圖：
10.拉伸切除得到四凹槽
如下圖：
11.底盤繪制完成后繼續(xù)往上繪制殼體身部，選擇上步使用的基準(zhǔn)平面進(jìn)行草繪
如下圖：
12.拉伸草繪圖形得到如下圖結(jié)構(gòu)
如下圖：
13.選擇剛拉伸圓柱的上平面為基準(zhǔn)面草繪如下線條
如下圖：
14拉伸后得到如下圖所示：
15.以上步得到的垂直平面為基準(zhǔn)面草繪如下尺寸圖形：
16.繼續(xù)拉伸得到下述圖形
17.選擇側(cè)平面為基準(zhǔn)面草繪如下尺寸圖形
18.拉伸后得到下圖
19.以最上平面為基準(zhǔn)面草繪上盤圖形
如下圖：
20.拉伸草繪圖形得到上盤
如下圖：
21.以上平面為基準(zhǔn)草繪
如下圖：
22.拉上上步草繪圖形得到側(cè)筋
如下圖：
23.草繪加強筋平面
如下圖：
24.拉伸加強筋
如下圖：
25.草繪殼體中心階梯孔
如下圖：
26.拉伸階梯孔
如下圖：
27.以階梯孔下平面為基準(zhǔn)面繪制通孔圓
如下圖：
28.拉伸通孔圓，得到如圖通孔
如下圖：
29.對階梯孔外周進(jìn)行倒角
如下圖：
30.同上
31.選取殼體側(cè)平面為基準(zhǔn)面草繪
如下圖：
32.拉伸切除后得到如圖凹槽
如下圖：
33.選擇殼體最上平面草繪圓
位置如下圖：
34.拉伸切除圓形
得到如下圖柱孔：
35.選擇殼體背面平面為基準(zhǔn)平面草繪
如下圖：
36.拉伸切除草繪圖形，得到如下圖凹孔：
37.以上步拉伸切除后成形的凹孔下平面為基準(zhǔn)面草繪如下圖尺寸圓：
38.拉伸切除得到如下圖凹孔：
39.以殼體側(cè)凸面為基準(zhǔn)面草繪圓
如下圖：
40.拉伸切除草繪圓得到如下圖所示凹孔：
41.以上步完成的凹孔下平面為基準(zhǔn)面草繪如下圖尺寸圓：
42.拉伸切除草繪圓得到如下圖所示孔：
43.以殼體最上平面為基準(zhǔn)面草繪如下圖所示六個圓：
44.拉伸切除草繪圓得到如下圖所示六個通孔：
45.以殼體頂蓋背面平面為基準(zhǔn)面草繪如下圖所示圓
46.拉伸切除草繪圓，得到如下圖所示階梯孔：
47.以殼體側(cè)平面切除面為基準(zhǔn)面草繪如下圖所示兩圓：
48.拉伸草繪圓：
如下圖：
49.試用螺旋掃面—切除命令繪制螺紋
如下圖：
50.選擇側(cè)加強筋孔試用上步命令繪制螺紋
如下圖：
最后安照圖紙要求R角標(biāo)準(zhǔn)進(jìn)行倒角，完成殼體三維繪圖
如下圖：
26
Cylinder block machining process design
Engine parts engine block is a more complex structure of spare parts box, its high precision, complex process, and the processing quality will affect the overall performance engine, so it has become the engine manufacturer's focus parts one.
Technical Characteristics of the engine cylinder block
Cylinder cast for a whole structure, and its upper part 4 cylinder mounting hole; cylinder standard cylinder is divided into upper and lower divisions into two parts; cylinder to the rear of the front-side arrangement of the previous three coaxial mounting hole of the camshaft and the idler axle hole.
Cylinder process features are: the structure of complex shape; processing plane, more than holes; uneven wall thickness and stiffness is low; processing of high precision typical of box-type processing part. The main processing of the surface of cylinder block top surface, the main bearing side, cylinder bore, the main and camshaft bearing bore holes and so on, they will directly affect the machining accuracy of the engine assembly precision and performance, mainly rely on precision equipment, industrial fixtures reliability and processing technology to ensure the reasonableness.
1.Engine block process design principles and the basis for
Design Technology program should be to ensure product quality at the same time, give full consideration to the production cycle, cost and environmental protection; based on the enterprises ability to actively adopt advanced process technology and equipment, and constantly enhance their level of technology. Engine block machining process design should follow the following basic principles:
(1) The selection of processing equipment ,the principle of selection adopted the principle of selection adopted the principle of combining rigid-flexible, processing each horizontal machining center is located mainly small operations with vertical machining center, the key process a crank hole, cylinder hole, balancer shaft hole High-speed processing of high-precision horizontal machining center, an upper and lower non-critical processes before and after the four-dimensional high-efficiency rough milling and have a certain adjustment range of special machine processing;
(2) focus on a key process in principle process the body cylinder bore, crankshaft hole, Balance Shaft hole surface finishing and the combination of precision milling cylinder head, using a process focused on a setup program to complete all processing elements in order to ensure product accuracy The key quality processes to meet the cylinder capacity and the relevant technical requirements;
According to the technological characteristics of automobile engine cylinder block and the production mandate, the engine block machining automatic production line is composed of horizontal machining center CWK500 and CWK500D machining centers, special milling/boring machine, vertical machining centers matec-30L and other appliances.
(1) top and bottom, and tile covered only the combination of aperture rough milling machine dedicated to this machine to double-sided horizontal milling machine, using moving table driven parts, machine tools imported Siemens S7-200PLC system control, machine control cabinet set up an independent, cutting automate the process is completed and two kinds of automatic and adjust the state;
(2) high-speed horizontal machining center machining center can be realized CWK500 the maximum flow of wet processing, but because of equipment, automatic BTA treatment system through the built-in tray under the wide-type chip conveyor and the completion of the machining center can be dry processing; machine tool spindle speed 6000r/min,rapid feeding speed 38m/min;
(3) The combination of front and rear face rough milling machine tool using hydraulic transmission; control system imported Siemens S7-200PLC system control, machine tools have a certain flexibility;
(4) The special machine TXK1500 this machine vertical machining center by the modification of shape, with vertical machining center features and performance, this machine has high strength, high wear-resistant, high stability, high accuracy, high-profile etc.;
(5) high-speed vertical machining center matec-30L of the machining center spindle high speed 9000r/min.Control system uses Siemens SINUMERIK840D control system;
(6) high-speed horizontal machining center spindle CWK500Dhighest speed 15000r/min.
2.Engine block machining process design the main content
Engine block complex structure, high precision, arge size, is thin-walled parts, there are a number of high precision plane and holes. Engine block machining process characteristics; mainly flat and the hole processing, processing of flat generally use planing, milling methods such as processing, processing of hole used mainly boring, processing and multi-purpose drilling holes. As the cylinder complex structure. so how to ensure that the mutual position of the surface processing precision is an important issue.
3.1 The selection of blank
Engine block on the materials used are generally gray cast iron HT150,HT200,HT250,there is also cast aluminum or steel plate, this engine block using high-strength alloy cast iron. Cylinder in the processing prior to aging treatment in order to eliminate stress and improve the rough casting mechanical properties.
Improve the rough accuracy, reduction of machining allowance, is to improve the automated production line system productivity and processing quality of the important measures. As the foreign box-type parts of rough quality and high precision, and its production-line system has been implemented directly on the blank line, not only eliminating the need for blank check device also saves the rough quality problems due to waste of machining time, increase overall efficiency. Therefore, the refinement of rough is to improve the productivity of the most promising way out. For the engine block production line, can be rough in parts on-line pre-milling six face, removing most of the margin, to facilitate direct on-line parts.
3.2 Machining process selection and processing of the benchmark
Choose the right processing technology base is directly related to the processing quality can ensure the parts. Generally speaking, process benchmarking can be divided into coarse and fine reference base.
(1) The baseline for the on-line thick rough, which is particularly important the choice of benchmark crude, if crude benchmark choice unreasonable, will the uneven distribution of machining allowance, processing and surface offsets, resulting in waste. In the cylinder production line, we have adopted for the coarse side of the base;
(2) Refined the base of this box for the engine block parts, the general use of "side two sales "for a full range of uniform benchmarks, For the longer automated production positioning, therefore, will be divided into 2-3 segment pin holes used. In the cylinder pin hole of the process, we have adopted to the side, bottom and the spindle hole positioning, in the processing center on the process.
3.3 Machining Processing Stages and processes of the arrangements
Often a part of many apparent need for processing, of course, the surface machining accuracy are different. Processing of high precision surface, often after repeated processing; As for the processing of the surface of low precision, only need to go through one or two on the list. Thus, when the development process in order to seize the "processing high precision surface, "this conflict, the reasonable arrangement processes and rational division stage of processing. Arrange the order of the principle of process is: after the first coarse refined, the first surface after the hole, the first benchmark other. In the engine block machining, the same should follow this principle.
(1) roughing stage engine block machining process, the arrangements for roughing process, to fully carry out rough rough, trim most of the margin in order to ensure production efficiency;
(2) semi-finishing phase of the engine block machining, in order to ensure the accuracy of the middle of some important surface processing, and arrange some semi-finishing operations, will be required accuracy and surface roughness of the surface of the middle of some processing to complete, while demanding the surface of semi-finished, to prepare for future finishing;
(3) The finishing stage of requiring high accuracy and surface roughness of the surface processing;
(4) secondary processing, such as small surface screw holes, you can finish of the major surface after the one hand, when the workpiece deformation process little impact at the same time also reduced the rejection rate;In addition,if the main surface of a waste,these small the surface will not have to be processed,thus avoiding a waste of man-hours.However,if the processing is very easy for a small surface bumps the main surface,it should be placed on a small surface finish prior to the main surface finishing;
(5) should make proper arrangements for secondary processes such as product inspection process,in part roughing stage,the key process before and after processing,spare parts all the processing has been completed,should be appropriate arrangements.
Stage of processing division,has the following advantages:First,it can take measures to eliminate the rough workpiece after the stress,to ensure accuracy; second,finishing on the back,and will not damage during transport the surface of the workpiece has been processed;again,first roughing the surface defects can be detected early and promptly deal with rough,do not waste working hours.But most small parts,do not sub very thin.
3.4 cylinder surface of the main processing and secondary processes
Cylinder surface and support the main processing operations are:
(1) plane processing at present, the milling of engine blocks is the primary means of planar processing,domestic milling feed rate is generally 300-400mm/min,and foreign 2000-4000mm/min milling feed rate compared to far cry,to be on increasing,therefore,improve the milling feed rate,reduce overhead time is to improve the productivity of the major means of finishing a number of plane engine block when the milling feed rate to reach 2399mm/min,greatly improved efficiency;
Top surface of the cylinder milling is a key process in the process,the flatness requirements for 0.02/145mm,the surface roughness of Ra1.6um.Processing in the cylinder,the use of side and spindle bearing bore positioning,top,bottom and middle vagay only aperture while processing used in the processing line outside of the knife device can better meet the engine block machining accuracy;
(2) General holes machining holes in general are still using the traditional processing of drilling,expansion,boring,reaming,tapping and other craft approach. Issues in the design process of specific programs,use of coated cutting tools,cutting tools and other advanced tools within the cooling,and using a large flow of cooling systems,greatly improving the cutting speed,improved productivity;
(3) deep hole processing of the traditional processing method is used to grade twist drill feed,low efficiency of their production,processing and quality is poor.The deep hole in the engine block processing,the use of gun drilling process;
(4) The three-axis machining holes for the cylinder-axis machining holes holes of high precision,long working hours of the restrictive process.Thus,work arrangements,processing methods,tools and so on should be special attention.All cover pre-processing,that is,semi-circular hole and the cylinder block main bearing cap of the shortage of processing,its main purpose is to remove blank margin,release stress,to prepare for the post-order processing;in crankshaft machining processing center hole,using double-sided Boring,boring the first holes in the crankshaft hole at one end to 1/2 length,and then turn 180 degrees workbench,form the other end and then bore another 1/2 length.
(5) The cylinder bore machining cylinder hole cylinder machining processing is a key process in the one,under normal circumstances,the machining process as a rough boring,semi-fine boring,precision boring and honing.Cylinder bore wall for the early detection of casting defects,eliminate stress,should be thick cylinder boring holes in advance;due to the structural characteristics of the different cylinder bore,must be in honing process to improve the cylinder bore surface quality.In the high-volume production,the cylinder bore honing generally use the multi-axis grinding machine or honing Automatic Line.Here we use honing automatic lines,from the coarse-heng.Fine-heng and testing equipment,composed of three;
(6) Cleaning cleaning isdivided into wet cleaning and dry cleaning.Machining cylinder automatic production line using a large flow of wet cleaning;
(7) Detect points outside the line detection and line detection of two kinds. Quality inspection in the engine block,according to the actual situation with lines outside the detection,the main use of coordinate measuring machine integrated measurements of the cylinder,each 200 samples 1-5 pieces,each class random one.
3.Summary
Through the engine block of the structure and process characteristics of the analysis,discusses the engine block machining process design principles and basis of the choice of cutting parameters,and U-turn at high speed milling and boring,for example,design,analysis of the engine cylinder body of high-speed milling and turnover boring process,and in the processing need to pay attention to.
加工工藝設(shè)計
缸體是零件中結(jié)構(gòu)較為復(fù)雜的箱體零件，其精度要求高，加工工藝復(fù)雜，并且加工加工質(zhì)量的好壞直接影響發(fā)動機整個機構(gòu)的性能，因此，它成為各個發(fā)動機生產(chǎn)廠家所關(guān)注的重點零件之一。
1.缸體的工藝特點
缸體為一整體鑄造結(jié)構(gòu)，其上部有4個缸套安裝孔；缸體的水平隔板將缸體分成上下兩部分；缸體的前端面從到后排列有三個同軸線的凸輪軸安裝孔和惰輪軸孔。
缸體的工藝特點是：結(jié)構(gòu)、形狀復(fù)雜；加工的平面和孔比較多；壁厚不均，剛度低；加工精度要求高，屬于典型的箱體類加工零件。缸體的主要加工表面有頂面、主軸承側(cè)面、缸孔、主軸承孔及凸輪軸孔等，它們的加工精度將直接影響發(fā)動機的裝配精度和工作性能，主要依靠設(shè)備進(jìn)度、工夾具的可靠性和加工工藝的合理性來保證。
2. 發(fā)動機缸體工藝方案設(shè)計原則和依據(jù)
設(shè)計工藝方案應(yīng)在保證產(chǎn)品質(zhì)量的同時，充分考慮生產(chǎn)周期、成本和環(huán)境保護(hù)；根據(jù)本企業(yè)能力，積極采用國內(nèi)外先進(jìn)的工藝技術(shù)和裝備，不斷提高企業(yè)工藝水平。發(fā)動機缸體機械加工工藝設(shè)計應(yīng)遵循以下基本原則：
（1）加工設(shè)備選型原則 加工設(shè)備選型采用剛?cè)峤Y(jié)合的原則，加工設(shè)備以臥式加工中心為主，少量采用立式加工中心，關(guān)鍵工序—曲軸孔、缸孔、平衡軸孔加工采用高精度高速臥式加工中心，非關(guān)鍵工序—上下前后四個平面的粗銑采用高效并有一定調(diào)整范圍的專用機床加工；
（2）集中工序原則 關(guān)鍵工序—曲軸孔、缸孔、平衡軸孔的精加工缸蓋結(jié)合面的精銑，采用在集中在一道工序一次裝夾完成全部加工內(nèi)容方案，以確保產(chǎn)品精度滿足缸體關(guān)鍵品質(zhì)的工藝性能和有關(guān)技術(shù)要求。
根據(jù)汽車發(fā)動機缸體的工藝特點和生產(chǎn)任務(wù)要求，發(fā)動機缸體機械加工自動生產(chǎn)線由臥式加工中心CWK500和CWK500D加工中心、專用銑/鏜床、立式加工中心matec-30L等設(shè)備組成。
（1）頂?shù)酌婕巴呱w止口面粗銑組合機床 本機床為雙面臥式專用銑床，采用移動工作臺帶動工件，機床采用進(jìn)口西門子S7-200PLC系統(tǒng)控制，機床設(shè)獨立電控柜，切削過程自動化完成，有自動和調(diào)整兩種狀態(tài)；
（2）高速臥式加工中心CWK500 該加工中心可實現(xiàn)最大流量的濕加工，但由于設(shè)備自動排屑處理系統(tǒng)是通過位于托盤下的內(nèi)置寬式排屑器而完成，該加工中心可以進(jìn)行干加工；機床主軸轉(zhuǎn)速6000r/min，快速進(jìn)給速度38m/min；
（3）前后端面粗銑組合機床 機床采用液壓傳動；控制系統(tǒng)采用進(jìn)口西門子S7-200PLC系統(tǒng)控制，機床具有一定的柔性；
（4）采用機床TXK1500 本機床有立式加工中心改造而成形，具備立式加工中心的特點及性能，該機床具有高精度、高強度、高耐磨度、高穩(wěn)定性、高配置等優(yōu)點；
（5）高速立式加工中心matec-30L 該加工中心主軸最高轉(zhuǎn)速9000 r/min?？刂葡到y(tǒng)采用西門子公司SINUMERIK840D控制系統(tǒng)
（6）高速臥式加工中心CWK500D 主軸最高轉(zhuǎn)速15000 r/min。
3. 發(fā)動機缸體機械加工工藝設(shè)計的主要內(nèi)容
發(fā)動機缸體結(jié)構(gòu)復(fù)雜，精度要求高，尺寸較大，是薄壁零件，有若干精度要求較高的平面和孔。發(fā)動機缸體機械加工的工藝特點是：主要是平面和孔的加工，加工平面一般采用刨、銑削等方法加工，加工孔主要采用鏜削，加工小孔多用鉆削。由于缸體結(jié)構(gòu)復(fù)雜，因此如何保證各表面的相互位置精度是加工中的一個重要問題。
3.1 毛坯的選擇
發(fā)動機缸體采用的材料一般是灰鑄鐵HT150、HT200、HT250，也有采用鑄鋁或者鋼板的，此發(fā)動機缸體采用高強度合金鑄鐵。缸體在加工前進(jìn)行時效處理，以消除鑄件內(nèi)應(yīng)力和改善毛坯的力學(xué)性能。
提高毛坯精度，減少加工余量，是提高自動生產(chǎn)線系統(tǒng)生產(chǎn)率及加工質(zhì)量的重要措施。由于國外箱體類零件毛坯質(zhì)量和精度較高，其生產(chǎn)線系統(tǒng)已實現(xiàn)了毛坯直接上線，既省去了毛坯檢查裝置，也節(jié)省了由于毛坯質(zhì)量問題而浪費的加工工時，提高了綜合效益。因此，精化毛坯是提高生產(chǎn)率最有潛力的出路。對于發(fā)動機缸體生產(chǎn)線，可在零件上線前粗銑六個面，去除大部分余量，便于零件直接上線。
3.2機械加工工藝基準(zhǔn)的選擇和加工
選擇合理的加工工藝基準(zhǔn)，直接關(guān)系到能否保證零件的加工質(zhì)量。一般來說，工藝基準(zhǔn)可分為粗基準(zhǔn)和精基準(zhǔn)。
（1）粗基準(zhǔn)對于上線的毛坯，其粗基準(zhǔn)的選擇尤為重要，如果粗基準(zhǔn)選擇不合理，會使加工余量分布不均勻，加工面偏移，造成廢品。在缸體生產(chǎn)線中，我們采用側(cè)面作為粗基準(zhǔn)；
（2）粗基準(zhǔn)對于發(fā)動機缸體這種箱體零件來說，一般采用“一面兩銷”為全線的統(tǒng)一基準(zhǔn)。對于較長的自動自動生產(chǎn)線系統(tǒng)，由于定位銷孔在使用過程中的磨損造成定位不準(zhǔn)確，因此，將定位銷孔分為2-3段使用。在缸體定位銷孔的加工中，我們采用了以側(cè)面、底面和主軸孔定位，在加工中心上加工。
3.3 機械加工加工階段的劃分和工序的安排
一個零件往往有許多表面需要加工，當(dāng)然表面的加工精度是不同的。加工精度較高的表面，往往要經(jīng)過多次加工；而對于加工精度低的表面，只要經(jīng)過一兩次就行了。因此，擬定工藝順序時，要抓住“加工精度高的表面”這個矛盾，合理安排工序和合理劃分加工階段。安排工藝順序的原則是：先粗后精，先面后孔，先基準(zhǔn)后其他。在發(fā)動機缸體的機械加工中同樣應(yīng)遵循這一原則。
（1）粗加工階段 在發(fā)動機缸體的機械加工過程中，安排粗加工工序，對毛坯全面進(jìn)行粗加工，切去大部分余量，以保證生產(chǎn)效率；
（2）半精加工階段 在發(fā)動機缸體的機械加工過程中，為了保證一些重要表面的加工精度，安排一些半精加工工序，將精度和表面粗造度要求中等的一些表面加工完成，而對要求高的表面進(jìn)行半精加工，為以后的精加工做準(zhǔn)備；
（3）精加工階段 對精度和表面粗造度要求高的表面進(jìn)行加工；
（4）次要小表面的加工 如螺紋孔，可以在精加工主要表面后進(jìn)行，一方面加工時對工件變形影響不大，同時廢品率也降低；另外，如果主要表面出廢品后，這些小表面就不必再加工了，從而避免浪費工時。但是，如果小表面的加工很容易碰傷主要表面時，就應(yīng)該把小表面加工放在主要表面的精加工之前；
（5）輔助工序也要妥善安排 如檢驗工序，在零件粗加工階段之后，關(guān)鍵工序加工前后，零件全部加工完畢后，都要適當(dāng)安排。
對加工階段進(jìn)行劃分，具有以下好處：首先，可以在粗加工后采取措施消除工作內(nèi)應(yīng)力，保證精度；其次，精加工放在最后面，不至于在運輸過程中損壞工件已加工表面；再次，先粗加工各面，可以及早發(fā)現(xiàn)毛坯缺陷并及時處理，不會浪費工時。不過對于一般小工件就不要分的很細(xì)。
3.4 缸體的主要加工表面和輔助工序
缸體主要加工表面和輔助工序有：
（1）平面加工 目前，銑削是發(fā)動機缸體平面加工的主要手段，國內(nèi)銑削進(jìn)給量一般為300-400mm/min，與國外銑削進(jìn)給量2000-4000 mm/min相比，相差甚遠(yuǎn)，有待于提高，因此，提高銑削進(jìn)給量，縮短輔助時間，是提高生產(chǎn)效率的主要途徑，發(fā)動機缸體精加工一些平面時的銑削進(jìn)給量達(dá)到2399mm/min，大大提高了效率；
頂面的銑削是缸體加工中的一個關(guān)鍵工序，其平面度要求為0.02/145mm，表面粗造度為Ra1.6um。在缸體的加工中，采用側(cè)面和主軸軸承孔定位，頂面、底面和中間瓦蓋面同時加工，在加工中采用線外對刀裝置，能較好地滿足發(fā)動機缸體加工精度要求；
（2）一般孔系的加工 一般孔系的加工仍采用傳統(tǒng)的鉆、擴(kuò)、鏜、鉸、攻絲等工藝方法。課題在設(shè)計具體的工藝方案時，采用涂層刀具、內(nèi)冷卻刀具等先進(jìn)刀具，采用大流量冷卻系統(tǒng)，大大提高了切削速度，提高了生產(chǎn)率；
（3）深油孔加工 傳統(tǒng)的加工方法是采用麻花鉆進(jìn)行分級進(jìn)給，其生產(chǎn)效率低，加工質(zhì)量差。在發(fā)動機缸體深油孔的加工中，采用槍鉆工藝；
（4）三軸孔的加工 三軸孔的加工為缸體孔系加工中精度要求高，工時長的限制性工序。因此，工序安排、加工方法、刀具等都應(yīng)該特別注意。合蓋前加工，既缸體半圓孔和主軸承蓋得加工，其主要目的是去除毛坯余量、釋放應(yīng)力，為后序加工做準(zhǔn)備；在加工中心上加工曲軸孔時，采用雙面鏜孔，先在曲軸孔一段端鏜孔到1/2長度時，然后工作臺回轉(zhuǎn)180度，從另外一端再鏜另一1/2長；
（5）缸孔的加工 缸孔的加工時缸體機械加工中的關(guān)鍵工序之一，一般情況下，其加工工藝過程為粗鏜、半精鏜、精鏜和珩磨。為及早發(fā)現(xiàn)缸孔內(nèi)壁的鑄造缺陷，消除應(yīng)力，應(yīng)盡量提前粗鏜缸孔；由于缸孔的結(jié)構(gòu)特點不同，需采用珩磨工藝，以提高缸孔表面質(zhì)量。在大批量生產(chǎn)中，缸孔的珩磨一般采用多軸珩磨機或珩磨自動線。再次我們采用珩磨自動線，由粗珩、精珩和檢測三臺設(shè)備組成；
（6）清洗 清洗分為濕式清洗和干式清洗。缸體機械加工自動生產(chǎn)線采用大流量濕式清洗；
（7）檢測 檢測分為在線檢測和線外檢測兩種。在發(fā)動機缸體的質(zhì)量檢測中，根據(jù)實際情況采用線外檢測，主要采用三坐標(biāo)測量機對缸體進(jìn)行綜合測量，每200件抽查1-5件，每班抽查一件。
4. 小結(jié)
通過對發(fā)動機缸體的結(jié)構(gòu)和工藝特點進(jìn)行分析，論述了發(fā)動機缸體機械加工工藝方案的原則和依據(jù)以及切削用量的選擇，并以高速銑削和調(diào)頭鏜孔為例，設(shè)計、分析了發(fā)動機缸體的高速銑削和調(diào)頭鏜孔工藝過程，及在加工中需要注意的問題。
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