1、某机床托架零件制造工艺及工装设计摘要：车床后托架是机床的附件，该零件的尺寸较小，虽然结构形状不是很复杂，但侧面的三杠孔和底面的加工精度要求较高，还有对顶面的四孔的加工精度有一定的要求。为保证零件的装配质量和寿命，必须保证其尺寸精度，几何精度，相对位置精度以及表面处理质量。该文主要分析机床托架的加工工艺及工装设计的要点和工艺制造方案。关键词：机床托架 制造工艺 工装设计机床托架为箱体类零件，主要是平面加工和孔系的加工。虽然平面加工精度要求较高，但加工精度比较容易控制，但孔系加工需要控制孔系的尺寸精度和为位置精度，还需要处理好孔系和平面的关系。1 托架个表面的加工方案机场托架的加工不但要达到设计要
2、求，还应具有良好的机械加工性，良好的加工工艺，不但确保了加工精度，而且能够提高加工效率。除此之外，加工设备的经济性，选择合理的机床设备。根据零件的表面技术要求，合理安排粗、精加工工序。根据材料的性质合理的加工工具，如经过淬火的材料，硬度较大，一般选用磨削或电加工的方式。如果是大批量生产，应选用专用机床，单件小批量则选择一般加工方法，提高本厂加工工艺水平。前期准备工序分别为粗车、半精车、淬火和粗磨，平面的加工依次为粗铣、精铣，孔的加工依次为粗镗、精镗，顶面四孔的加工依次为钻、扩、铰。2 定位基准的确定2.1 粗基准的确定选择精加工基准时，为保证加工面与不加工面的位置精度关系，应选择位置精度较高的
3、表面为粗基准，或重要的表面微基准；为保证该表面有足够的加工余量，应选择加工余量最小的为粗基准；为保证零件能够准定位，应选择平整、光洁的表面为粗基准，同时粗基准不能同时使用。考虑以上因素，机床后托架应选择侧面三孔为粗加工基准。2.2 精基准的确定为避免定位基准与设计基准不重合而产生不重合误差，应尽可能选择设计基准为精基准；为避免基准转换带来的位置误差，应尽可能的选择统一的基准；加工两个被加工面时，难以确定定位基准，可以互为基准提高加工精度；此外，为保证零件加工时的稳固性，选择尺寸较大的平面为精基准。通过以上分析，结合本零件的特点，选择底面和顶面两孔为精加工基准。3 工艺路线的制定3.1 加工阶段
4、的划分首先加工统一的基准，先以孔定位粗、精加工顶平面，然后安排粗精加工工序。其加工阶段分为粗加工、半精加工、精加工和光整加工四个加工阶段。3.1.1 零件的粗加工粗加工的目的是削去绝大部分金属，为半精加工和精加工提供定位基准。但粗加工过程中，切削余量大，切削力加大，切削产生的热量多，切削变形大，加工精度低。一半粗加工的公差等级为 IT11-IT12，粗糙度为 Ra80-100um。3.1.2 半精加工半精加工是为主要面的精加工做好准备，为避免零件的变形，选择合理的加工余量和切削速度。其公差等级为 IT9-IT10，便面粗糙度为 Ra10-1.25um。3.1.3 精加工精加工阶段用于切除剩余的
5、材料，到达设计要求的尺寸精度、位置精度和表面粗糙度，加工精度一般为 IT6-IT17，表面粗糙度为 Ra10-1.25um,为防止零件的划伤，精加工安排的零件的加工的最后。3.1.4 光整加工对于有较高表面质量要求的零件，往往通过光整加工，改善其表面质量。3.2 加工路线的设计铸造-清砂-热处理（退火）-检验毛坯-铣底面-粗镗空-粗铣油槽-半精镗孔-精镗空-钻顶面四孔-锪孔-铰孔-转侧面两空-攻丝-去毛刺-检验-入库4 专用夹具设计为提高加工精度，提高加工效率，降低工人的劳动强度，需要为机床后托架设计专用夹具，主要是为加工孔和铣底面设计夹具。4.1 铣平面夹具的设计铣机床后托架的底面，应满足侧
6、面三孔的尺寸和平行度要求，同时考虑零件的生产效率，使用 V 型块作为自动找侧面三孔的中心线夹具，由于该构件体积小，易于切削，考虑选用手动加紧方式，并按照机床夹具设计手册对其铣削力和夹具的加紧力经行分析，分析加紧机构的可靠性。当工作过程中出现磨损或零件尺寸放生变化时，应根据设计情况使用支撑钉和 V 形块进行调节。4.2 镗孔夹具的设计镗孔主要是加工侧面三孔，除了满足轴线对平面的平行度要求外还应满足表满粗糙度的要求，由于底面经过粗铣，所以选择底面为定位精基准，并以左侧面和后侧面为定位基准来设计镗模，加紧机构仍然选择手动螺旋加紧机构。为满足加工工序的要求，还应根据互换性与技术测量和机床夹具设计手册分
7、析夹具和定位方式是否满足孔轴线与左侧面的尺寸公差及平行度公差。4.3 顶面四孔夹具的设计由于顶面四孔没有位置公差的要求，应选择左侧面和后侧面为定位基准来设计钻模，加上底面共限制 5 个自由度，满足定位要求。为保证该工序的公差小于工序的规定的公差，需要保证孔轴线与左侧面的尺寸公差，即定位误差、加紧安装误差、磨损造成的误差以及刀具和夹具的相对误差的总和小与规定误差。5 结语机床托架的零件制造虽然工序不复杂，但工艺路线的制定和夹具的设计依然应高度重视，只有合理科学的安排加工工序，不断提高夹具的设计精度，才能提高零件的加工精度和生产效率，根据现有条件，设计适合本厂的加工工艺，提高机床托架零件的工艺制造
8、水平。参考文献【1】赵家齐.机械制造工艺学课程设计指导书.2 版北京：机械工业出版社,2000.【2】史全福.金属切削手册.3 版.上海：上海科学技术出版社，2000.【3】陈家芬.实用金属切削加工工艺手册.2 版.上海上海科学技术出版社,2005.A Machine Bracket Parts Manufacturing Process and Tooling DesignAbstract: the lathe after the bracket is machine tool attachment ,the size of the parts is small, although the
9、shape of the structure is not very complicated, but the side of The three lever hole and the bottom of the machining precision requirement is high, and the top surface of the machining accuracy of the four-hole has certain requirements. In order to ensure the quality and life of the assembly and par
10、ts of life, must ensure the dimensional accuracy and geometric accuracy, the relative position precision and surface processing quality. This paper mainly analyzes the key points of bracket machine processing technology and tooling design elements and process manufacturing solutions.Keywords: machin
11、e bracket manufacturing process tooling designThe machine bracket for box-type parts, processing is mainly plane processing and holes. Although the plane process require high precision, the processing precision is easy to control, but the hole processing need to control the pore system of the dimens
12、ional accuracy and positional accuracy, also need to deal with the relationship between hole and plane.The 1 bracket surface processing schemeAirport bracket processing not only to meet the design requirements, but also has good machinability, good process, not only ensures the precision, but also c
13、an improve the processing efficiency. In addition, the economic efficiency of processing equipment, a reasonable choice of machine tools. According to the technical requirements of the part surface, reasonable arrangements for roughing and fine finishing process. According to the reasonable nature o
14、f the processing tools and materials, such as quenched materials, which is very hard, generally used in grinding or EDM approach. If mass-produced, should use special tools, single and small quantities? select general processing methods to improve the level of processing factory. Preparatory steps w
15、ere roughing, semi-finishing car, quenched and coarse grinding, plane processing were rough milling, precision milling, hole machining were rough boring, fine boring, the top surface of the processing order of the four-hole drilling, expanding , hinges.2. Determine the location datum2.1 Determinatio
16、n of crude benchmarkIn order to ensure the accuracy relationship between the position of the machined surface and not machined surface, we should choose a higher position accuracy surface as reference or important surface as reference when selecting finishing benchmarks. To ensure that the surface h
17、as enough allowance, we should select the smallest allowance for crude benchmark; To ensure the parts to precise positioning, we should choose flat, smooth surface as rough benchmark, and benchmark crude cannot be used simultaneously. Considering the above factors, we should select the side three ho
18、les as rough machining datum for bracket machine after.2.2 Determination of fine benchmarkTo avoid locating datum does not coincide with the design basis and produce no coincidence error, we should choose the design basis for the fine as a reference; to avoid position errors caused by datum transfor
19、mation we should set a single datum; when processing the two machined surfaces , it is difficult to determine the positioning reference, the reference can improve the machining accuracy of each other; In addition, to ensure stability during processing part, selecting a larger size for the fine refer
20、ence plane. Through the above analysis, combined with the characteristics of the parts, select two holes to finish bottom and top surfaces benchmark.3 the set of process route3.1 division processing stagesFirst, to set a unified benchmark, first to locate the hole rough, finishing top of the plane,
21、and then arrange rough finishing operations. The processing stage is divided into roughing, semi-finishing, finishing and finishing four stages of processing.3.1.1 Parts roughing machiningThe aim is to cut away most of the rough metal, provide positioning reference for semi-finishing and finishing.
22、But roughing process, cutting a large margin, the cutting forces increase, the heat generated by cutting, large cutting deformation, low precision. Half roughing tolerance class IT11-IT12, roughness Ra80-100um3.1.2 Semi finishes machiningSemi finishing is ready for the main surface finishing, avoidi
23、ng the deformation of parts, choosing a reasonable allowance for machining and cutting speed. The tolerance levels for the IT9-IT10, the surface roughness of Ra10-1.25um.3.1.3 FinishingFinishing stage for the removal of the remaining material to reach the required dimensional accuracy of the design,
24、 location accuracy and surface roughness, machining accuracy is generally IT6-IT17, surface roughness Ra10-1.25um, to prevent scratching of parts, finishing arrangements for the final part of the .3.1.4 FinishingFor a higher surface quality requirements of the parts, often through finishing, improve
25、 surface quality.3.2 Design of processing routesCasting - sand - heat treatment (annealing) - Inspection rough - milling underside - rough boring empty - roughing the tank - semi-fine boring - fine boring empty - the top surface of the four-hole drilling - countersinking - reaming - turn two empty s
26、ide - tapping - demurring - Inspection - Storage4 special fixture designsTo improve the precision, improve processing efficiency; reduce labor intensity, the need for special fixtures after the machine bracket design, mainly for holes and milling underside design fixtures.4.1 milling plane fixture d
27、esignAfter milling the bottom surface of the bracket, the sides should meet three holes the size and parallel degree requirements, taking into account the productivity of parts, using the V-block as an automatic three-hole side of the centerline of the fixture to find, since the members are small an
28、d easy cutting , consider using manual methods to intensify, and its milling force and clamp force intensified by the line analysis, reliability analysis in accordance with the agency to step up, “fixture design Manual.“ When worn or release part size changes occur during operation should be used to
29、 support the nail and V-block design be adjusted according to the situation.Boring fixture design 4.2Is the main processing side hole boring, in addition to meet the requirements of the parallelism of the axis plane should also satisfy the table full of roughness requirements, because the bottom sur
30、face through the rough milling, so the choice of the bottom surface is positioning precise basis, and to the left side and rear side as the positioning reference to design of boring die, clamping mechanism still choose manual spiral the clamping mechanism. In order to meet the requirements of machin
31、ing process, also should be based on the “analysis of interchangeability and technical measurement“ and “machine fixture design handbook“ clamps and locating way whether meet the dimensional tolerances of hole axis and the left side and parallelism tolerances.Design of 4.3 top four holes jigThe top
32、surface of the four holes without position tolerance requirements should choose the left side and rear side as the positioning reference to the design of drilling jig, coupled with the bottom surface of a total limit of 5 degrees of freedom, to meet the positioning requirements. In order to ensure t
33、hat the specified tolerance of less than the processes of the process tolerances, the need to ensure dimensional tolerances of hole axis and the left side of the positioning error, i.e., stepping up installation error and wear caused by the error and the sum of small and provisions of the relative e
34、rror of tool and fixture error.5. ConclusionThe machine bracket parts manufacturing although process is not complicated, but the formulation and fixture design process route still should pay attention to, the only reasonable scientific arrangement of working procedure, and constantly improve the des
35、ign accuracy of the fixture, in order to improve the machining precision and efficiency, according to the present condition, the design is suitable for processing factory, improve process the machine bracket parts manufacturing level.Reference1 Zhao Jiaqi. Mechanical manufacturing technology curricu
36、lum design guide book version.2 Beijing: Mechanical Industry Press, 20002 Shi Quanfu. Metal cutting version.3 of the manual Shanghai: Shanghai science and Technology Press, 20003Chen Jiafen. Practical Handbook of metal cutting processing technology.2.Shanghai Shanghai science and Technology Press, 2005
