1、连杆是柴油机的主要传动件之一，本文主要论述了连杆的加工工艺及其夹具设计。连杆的尺寸精度、形状精度以及位置精度的要求都很高，而连杆的刚性比较差，容易产生变形，因此在安排工艺过程时，就需要把各主要表面的粗精加工工序分开。逐步减少加工余量、切削力及内应力的作用，并修正加工后的变形，就能最后达到零件的技术要求。连杆零件加工工艺 大量生产的工艺特征：零件的互换性：具有广泛的互换性，少数装配精度较高处，采用分组装配法和调整法。毛坯的制造方法和加工余：广泛采用金属模机器造型，铸或其他商效方法。毛坯精度高，加工余量小。机床设备及其布置形式：广泛采用商效专用机床及自动机床，按流水线和自动排列设备。工艺装备：广泛
2、采用高效夹具，复合刀具，专用量具或自动检验装置，靠调整法达到精度要求。对工人的技术要求：对调整工的技术水平要求高，对操作工的技术水平要求较低。工艺文件：有工艺过程卡或工序卡，关键工序要调整卡和检验卡。成本：较低。生产率：高。工人劳动条件：较好。第二节 零件的分析一、零件的分析（1）加工表面的尺寸精度和形状精度。（2）主要加工表面之间的相互位置精度。（3）加工表面的粗糙度及其他方面的表面质量要求。（4）热处理及其他要求。连杆零件的图样的视图正确，完整，尺寸，公差及技术要求齐全。但基准孔14H8mm要求Ra1.6m比较高，需要绞孔。本零件的两大小头孔的加工并不困难。根据零件的技术要求，其大小头孔的
3、两中心的平行度要求比较高，达0.08mm，因此在加工时应设计一夹具来保证两孔中心的平行度要求。另外就是该零件的油槽加工，分析该小孔是做油孔之用，位置精度不需要太高，只要钻至沟槽之内，即能使油路畅通就行。再就是铣小头孔上十字形通槽，需要设计一夹具来加工。二、选择毛坯及毛坯制造方法(1) 根据零件用途确定毛坯类型。(2)根据批量（生产纲领）确定毛坯制造方法。(3)根据手册查定表面加工余量及余量公差。根据技术要求，零件材料为ZG310570，即铸造碳钢。主要化学成分W% 主要特性 用途举例 C Si Mn P S不大于0.40 0.50 0.90 0.04 0.04 有较好强度、塑性、焊接、性能尚好
4、。 轨刚机架模具、箱体、缸体连杆、曲轴等。 热处理 正火或退火温度 回火温度 870890 620680 机械性能bN/mm2 sN/mm2 s% % kJ/cm2 570 310 15 21 30 按GB/T56131995规定，铸钢牌号用“铸”和“钢”两字汉语拼音首位字母“ZG”后加工两组数字表示，第一组数字表示屈服点的最低值，第二组数字表示抗拉强度的最低值。ZG310570表示s310MPa，B570MPa的铸钢。铸造碳钢的碳质量分数一般为0.15%0.6%，其铸造性能比铸造铁差，但力学性能比铸造铁好。主要用于制造形状复杂，力学性能要求高，而在工艺又很锻压等方法成形的比较重要的机械零件，
5、例如汽车的变速箱壳，机车车辆的车销和联轴器等。铸造碳钢的牌号，化学成分，力学性能见表 毛坯的制造方法：根据毛坯的材料，生产类型，生产纲领及零件的复杂程度，毛坯可采用铸成型。零件并不复杂，因此毛坯可以与零件的形状尽量接近。两孔可不必锻出，直接加工。通过查加工余量表，得两端面的总加工余量为3mm，毛坯尺寸可以通过加工余量确定。选择毛坯铸的主要依据：铸可锻造形状复杂的毛坯，尺寸精度较高，尺寸偏差0.1mm0.2mm，表面粗糙度Ra为12.5m，毛坯的钎维组织好，强度高，生产率较高，但需要专用锻模及锻锤设备。大批量生产，适于锻造碳素钢，合金钢。 锻件加工表面直线度，平面度公差。铸件长度为160mm，热
6、处理为调质时，直线度和平面度公差的普通级为1.1mm，精密度为0.7mm。第三节 工艺规程设计一、定位基面的选择定位基面的选择是拟定零件的机械加工路线，确定加工方案中首先要做的重要工作。基面选择得正确、合理与否，将直接影响工件的加工质量和生产率。在选择定位基面时，需要同时考虑以下三个问题：(1) 以哪一个表面作为加工时的精基面或统一基准，(2) 才能保证加工精度，(3) 使整个机械加工工艺过程顺利地进行?(4) 为加工上述精基面或统一基准，(5) 应采用哪一个表面作为粗基面?(6) 是否有个别工序为了特殊的加工要求，(7) 需要采用统一基准以外的精基面?精基面的选择：根据精基面的选择原则，选择
7、精基面时，首先应考虑基准重合的问题，即在可能的情况下，应尽量选择加工表面的设计基准为定位基准。 在连杆机械加工工艺过程中，大部分工序选用连杆的一个指定的端面和小头孔作为主要基面，并用大头孔处指定一侧的外圆面作为另一基面。这是由于：端面的面积大，定位比较稳定；用小头孔定位可直接控制大小头孔的中心距。这样就使各工序的定位基准统一起来，减少定位误差。再深入研究一下：根据零件图，连杆零件的大小头孔有一端面（即右端面）在一个平 面上，因此可以同时加工出来，但另一端面（即左端面）不在一个平面上，这对作为定位基准面来说是不利的。因此，在加工时需主意其定位方案的合理性。小头孔外圆作为基面，所以小头孔外圆表面的
8、加工安排得比较早。 在小头孔与大头孔作为定位基面前的加工工序且钻孔、扩孔、铰孔，这些工序对于加工后的孔与孔的平行度不易保证，有时会影响到后续工序的加工精度，因此，在加工时应注意，选用合理的定位方案。在第一道工序中，工件的各个表面都是毛坯表面，定位和夹紧的条件都较差，而加工余量和切削力都较大，如果再遇上工件本身的刚性差，则对加工精度会有很大影响，因此第一道工序的定位和夹紧方法的选择，对于整个工艺过程的加工精度常有深远的影响。连杆加工就是如此。在粗铣中工件如何定位呢？一个方法是以毛坯端面定位，在侧面和端部夹紧，粗铣一个端面后，翻身，以铣好的面定位，铣另一个毛坯面。但是由于毛坯表面 不平整，连杆的刚
9、性差，定位夹紧时工件可能变形，粗铣后端面似乎平整了，一放松，工件又恢复变形，影响后续工序的定位精度。关键词: 连杆 变形 加工工艺 夹具设计The connecting rod is one of the main driving medium of diesel engine, this text expounds mainly the machining technology and the design of clamping device of the connecting rod. The precision of size, the precision of profile and
10、 the precision of position , of the connecting rod is demanded highly , and the rigidity of the connecting rod is not enough, easy to deform, so arranging the craft course, need to separate the each main and superficial thick finish machining process. Reduce the function of processing the surplus ,
11、cutting force and internal stress progressively , revise the deformation after processing, can reach the specification requirement for the part finally . Keyword: Connecting rod Deformination Processing technology Design of clamping deviceConnecting parts processing technologyMass production process
12、 features:The interchangeable parts: widespread interchangeability, assembling accuracy is high, the minority group assembly method and usingThe whole law.The manufacturing process and method of blank over: widely used metal mould casting machine model, or other business efficiency. blankHigh precis
13、ion, small machining allowance.Machine equipment and its layout forms: widely used for business efficiency and automatic machine tools, and automatic assembly lineEquipment.Process equipment: widely used efficiently, composite cutter, special jig automatic test device, measuring or by aaaMeet precis
14、ion requirements.The technical requirements for workers to DiaoZhengGong technical level, high technology level of operators, low requirements.Process documents: process card or process card, key procedure should adjust the card and card.Low cost:.Productivity: high.Labor conditions: good.The second
15、 section of the analysis of the componentsA, the analysis of the components(1) the processing precision and surface shape accuracy.(2) the interaction between the main processing surface position accuracy.(3) processing surface roughness and other aspects of the surface quality requirements.(4) heat
16、 treatment and other requirements.The pattern of connecting parts, complete and correct view size, tolerance and technical requirements. But the benchmark hole 14H8mm requirements Ra1.6 muon m high, need hole. This part of the two size head hole machining is not difficult. According to the technical
17、 requirements of the parts of the two centers head size hole parallel degree more demanding, of 0.08 mmIn the process, so when a fixture should be designed to ensure the parallel hole center. Another is the partsOil processing, analysis of the oil hole hole is doing with high precision, need not, as
18、 long as the drill to grooveOil can make clear, namely. Or milling small head hole groove, cross through a fixture design needs to processing.Second, the choice method and blank blank(1) to determine the blank type parts purposes.(2) according to the batch production program () method blank.(3) shal
19、l be determined according to the manual surface machining allowance allowance and tolerance.According to the technical requirement, material for ZG310-570 parts, namely cast steel.Main chemical compositions W % main characteristics for purposesC Si Mn P SNot more than0.40 0.50 0.90 0.04 0.04 has goo
20、d strength, plastic, welding, performance is good. Rail just frameMould, box, cylinder rods, crankshaft etc.heatIs the fire temperature c or annealing temperature c tempered870-62-680 890Mechanical propertiesSigma b N/mm 2 s N/mm 2 delta % s % k J/cm 2570 310 15 and 30According to GB/T5613-1995, wit
21、h cast steel brand and steel letters first ZG pinyinAfter two group, digital processing of the first group of low yield point number, the second group of numerals tensileLow intensity.ZG310-570 said s p 310MPa, B 570MPa experiment.it steel. The carbon steel casting quality score0.15% - 0.6 percent,
22、the properties of casting iron foundry than poor, but the mechanical properties of casting iron than. Mainly used for manufacturingComplex shape, high mechanical properties, and in the process and methods of forming of metalforming machine is importantA car gearbox shell, for example, the locomotive
23、s car sales and couplings etc. Casting steel grades, and chemicalComposition, mechanical properties tableMethods: the manufacturing blankAccording to the material, producing blank type, production program and parts of complexity, can use cast forming.Parts not complex, therefore blank can be as clos
24、e as possible to the shape of parts. Two holes can not directly, forgingWork.By looking at more than processing, the scale of total limits.but for 3mm, blank dimensions can through limits.but indeedFixed.The main basis of casting billet choice: casting forging shape can be complex and size precision
25、, size deviation0.1 mm 0.2 mm, surface roughness Ra to 12.5 muon m, organize the brazing dimension, high strength, productivityHigh, but need special forging die forging and equipment.Mass production, suitable for carbon steel, alloy steel forging.Straightness, sugar processing surface flatness tole
26、rance.Casting for 160mm, heat treatment for length of conditioning, straightness tolerances of peaceful face degrees for 1.1 mm, constructionDensity 0.7 mm.The third quarter design procedureThe selection of base and positioningThe base position is protocol machining line, determine the processing pl
27、an of the important work to do firstMake. Choose correctly, the yankees will directly influence the reasonable or not, the machining of quality and productivity.When selecting position in the plane, need to consider the following questions:(1) in which a surface as the essence and surface or unified
28、 standards, (2) to ensure machining precision, (3)Make the machining process smoothly?(4) for processing the pure plane or unity, (5) should be adopted as a rough surface plane?(6) whether individual processes for special processing requirements, (7) need to employ unified standards of plane outside
29、?According to the essence and the yankees choice: fine, fine and selection principles should be considered when the first, the benchmark overlapIn may, namely, under the situation of the machined surface should be chosen for the locating datum design standards.In the process of connecting the machin
30、ing process, most of a specified process selection of end and small head holeAs the main base, with big hole in the side outside the designated as another round face includes surface. This is due to the face. Large area, more stable, With little head position can directly control size hole hole cent
31、er distance of the head. It makesThe process of locating datum, reduce positioning error.Further study: again,According to the drawing, the size of the connecting parts have a head hole surface (namely the right end) in a flat surface,Therefore, but can also be processed another end (left) is not an
32、 end, for the plane asIt is disadvantageous position datum. Therefore, in the process of the localization plan to idea.As the yankees round hole small head, so little head outside surface processing round hole arrangement early. In small head and largeBefore the yankees head hole as orientation of the m
