文献翻译—机床夹具设计分析.doc

Lathe fixture design and analysis(School of Mechanical Engineering, Hefei, Anhui Hefei 230022, China)Abstract: From the start the main types of lathe fixture, fixture on the flower disc and angle iron clamp lathe was introduced, and on the basis of analysis of a lathe fixture design points.Keywords: lathe fixture; design; pointsLathe for machining parts on the rotating surface, such as the outer cylinder, inner cylinder and so on. Parts in the processing, the fixture can be installed in the lathe with rotary machine with main primary uranium movement. However, in order to expand the use of lathe, the work piece can also be installed in the lathe of the pallet, tool mounted on the spindle.THE MAIN TYPES OF LATHE FIXTURE Installed on the lathe spindle on the lathe fixtureInstalled in the fixture on the lathe spindle in addition to three-jaw chuck, four jaw chuck, faceplate, front and rear dial with heart-shaped thimble and a combination of general-purpose lathe fixture folder outside (as these fixtures have been standardized and machine tool accessories, can be purchased when needed do not have to re-design), usually need to design special lathe fixture. Common special lathe folder with the following types.Fixture took disc latheThis process is to find the generic is installed on the faceplate is difficult to ensure the accuracy of the workpiece, so the need to design special lathe fixture. The lathe fixture design process, first select the cylindrical workpiece and the end cylinder B, the semi-circular surface finishing (finishing second circular surface when the car has been good with circular surface) is positioned datum, limit of six degrees of freedom, in line with the principle of base overlap.The work piece fixture to ensure the accuracy of measures:The workpiece fixture to ensure the accuracy of measures:(1) tool by the workpiece machining position relative to the guarantee. (2) symmetry of size 0.02. Rely on sets of holes and positioning theworkpiece with the precision of and locate the position of dimensional accuracy and process specification requirements to ensure that the same parts of the four circular surface must be processed on the same pins.(3) all fixtures and clip bushing hole axis vertical concrete face A tolerance of .because the A side is the fixture with the lathe when the transition assembly base plate installed.(4) specific folder on the -hole plate with the transition to the benchmarks pin design requires processing each batch of parts to be sold in the transitional disk with a coat made of a tight match, and the local processing of the face plate to reduce the transition fixture on the set of small errors.The angle iron fixtureIf the processing technology for the and , drilling, boring, reaming process scheme. Boring is required in the face A face of finishing B ( range) and the A, B sides and the hole axis face runout does not exceed . In addition, the processing of -hole, you should also ensure that its axis with the axis of the degree of tolerance for the uranium ; size and the location of ; and and of the axis of the axis of displacement tolerance not more than .Based on the above analysis on the part of process size, choose the -hole on the workpiece surface and M, N two planes to locate the benchmark.Installed on the lathe pallet fixtureLimited equipment in the factory, similar to the shape of the parts box, its small size, designed for easy installation without turning the main pumping in the fixture, you can drag the panel removal tool holder, fixture and workpiece mounted on the pallet. Processing, mounted on the lathe tool on the main primary uranium movement, feed the work piece for movement, so you can expand the scope of application of lathe.LATHE FIXTURE DESIGN POINTSThe design features of the positioning deviceLathe fixture positioning device in the design, in addition to considering the limited degrees of freedom, the most important thing is to make the surface of the workpiece axis coincides with the axis of spindle rotation. This is described in the previous two sets of lathe fixture when special emphasis. In addition, the positioning device components in the specific folder location on the workpiece surface accuracy and dimensional accuracy of the location has a direct relationship, so the total figure on the fixture, be sure to mark the location positioning device dimensions and tolerances, and acceptance as a fixture conditions.Jig weight design requirementsProcessing in the lathe, the workpiece rotation together with the fixture will be a great centrifugal force and the centrifugal force increases sharply with increasing speed. This precision machining, processing, and the vibration would affect the surface quality of parts. Therefore, the lathe fixture between devices should pay attention to the layout of equipment necessary to balance the design weights.Dlamping device design requirementsLathe fixture in the course of their work should be the role of centrifugal force and cutting force, the size of its force and direction of the workpiece position relative to the base is changing. Therefore, a sufficient clamping device clamping force and a good self-locking. To ensure safe and reliable clamping. However, the clamping force can not be too large, and require a reasonable layout of the force, and will not undermine the accuracy of the location positioning device.Llathe fixture connection with the machine tool spindle designLathe fixture connected with the spindle directly affects the accuracy of the rotary fixture accuracy, resulting in errors in the workpiece. Therefore, the required fixture rotation axis lathe spindle axis with high concentricity.Lathe fixture connected with the spindle structure, depending on the spindle when turning the front of the structure model is confirmed, by machine instructions or the manual check on. Lathe spindle nose are generally outside the car with cone and cone, or a journal and other structures with the flange end connections to the fixture base. Note, however, check the manual should be used with caution, because many manufacturers of machine tools, machine tools of similar size may differ. The most reliable method for determining, or to field measurements in order to avoid errors or losses.Determine the fixture and the spindle connecting structure, generally based on fixture size of the size of the radial: radial dimension less than , or small lathe fixture.Pairs of fixture requirements of the overall structureLathe fixture generally work in the state of the cantilever in order to ensure process stability, compact fixture structure should be simple, lightweight and safe, overhang length to as small as possible, the center of gravity close to the front spindle bearing. Fixture overhang length L and the ratio of outer diameter D profile can refer to the following values used:Less than the diameter D in fixture, ; Diameter D between the fixture in , ; Fixture diameter D is greater than , .To ensure security, installed in the specific folder on the components of the folder is not allowed out beyond the specific diameter, should also consider cutting the wound and coolant splash and other issues affecting safe operation.翻译：车床夹具设计分析摘 要：从车床夹具的主要类型着手，对花盘式车床夹具和角铁式夹具进行了介绍，并在此基础上分析了车床夹具设计要点。关键词：车床夹具；设计；要点 车床主要用于加工零件上的回转表面，如外圆柱面、内圆柱面等。零件在加工时，可安装在车床夹具上同机床主铀一起回转作主运动。但为扩大车床的使用范围，也可将工件安装在车床的拖板上，刀具装在主轴上。1 车床夹具的主要类型1.1 安装在车床主轴上的车床夹具 安装在车床主轴上的夹具除三爪卡盘、四爪卡盘、花盘、前后顶针以及拨盘与鸡心夹的组合通用车床夹具外（这些夹具现已标准化并作为机床附件，需用时可购买不必重新设计)，通常还需设计专用车床夹具。常见的专用车床夹具有以下几种类型1.1.1 花盘式车床夹具 这道工序若要在通用花盘上找正安装是难以保证工件精度要求的，所以需要设计专用车床夹具。设计该工序的车床夹具，首先选定工件外圆柱面与端面B、半精车的圆弧面（精车第二个圆弧面时则用已经车好的圆弧面）为定位基准面、限制了6个自由度，符合基准重合原则。 该夹具保证工件加工精度的措施有： （1）靠工件相对于刀具的加工位置保证。 （2）尺寸对称度0.02。依靠定位套孔与工件的配合精度与定位的位置尺寸精度来保证且工艺规程要求同一工件的4个圆弧面必须在同一定位销上进行加工。 （3）夹具的所有衬套孔的轴线与夹具体的端面A垂直度公差为因为A面是夹具与车床过渡盘安装时的装配基准。 （4）夹具体上孔为与过渡盘上销的对定基准，设计要求每批零件加工时都要在过渡盘上装销配作成较紧的配合,且就地加工过渡盘端面以减小夹具的对定误差。1.1.2 角铁式夹具 若加工和的工艺为钻、镗、铰的工艺方案。在镗孔时需精车端面A端面B （范围内） 且A、B两面与孔 轴线的端面跳动量不超过。此外，加工孔时，还应保证其轴线与 轴线的同铀度允差为； 的位置尺寸为和；和的轴线与的轴线位移度公差不得大于。 根据以上对零件工序尺寸的分析，选工件上的孔表面和M、N两个平面为定位基准。1.1.3 安装在车床拖板上的夹具 在工厂设备有限时，类似箱体形状的零件，其尺寸较小，不便于设计成安装在车床主抽上的夹具，可以将拖板上的刀架拆除，夹具和工件安装在拖板上。加工时，装在车床主铀上的刀具作主运动，工件作进给运动，这样可以扩大车床的应用范围。2 车床夹具设计要点2.1 定