附录ALathe fixture design and analysisMa Feiyue(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 FIXTUREInstalled 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 fixtureΦand the end cylinder B, design process, first select the cylindrical workpiece 5.56hΦsemi-circular surface finishing (finishing second circular surface when the the 22.5car has been good with 0.023023+Φ 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) 0.023023+Φ tool by the workpiece machining position relative to the guarantee. (2) symmetry of 180.02± size 0.02. Rely on sets of holes and positioning theworkpiece with the precision of 5.56h Φ and0.0100.00220.5++Φ 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 0.005mm .because the A side is the fixture with the lathe when the transition assembly base plate installed.(4) specific folder on the 207H Φ-hole plate with the transition to the benchmarks 20Φ 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 0.0102.5+Φ and 0.0110.00510++Φ, drilling, boring, reamingprocess scheme. Boring is required in the face A face of finishing B (12Φ range) and the A, B sides and the hole 10Φ axis face runout does not exceed 0.02mm . In addition, the processing of 2.5Φ-hole, you should also ensure that its axis with the axis of the 0.0110.00510++Φ degree of tolerance for the uranium 0.01mm Φ; 10Φ size15.50.1± and the location of 80.1mm ±; 2.5Φ and 10Φ and 17.5Φ of the axis of the axis of displacement tolerance not more than 0.02mm .Based on the above analysis on the part of process size, choose the 17.5Φ-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 rotaryfixture 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 140mm , or (23)D d <- 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 150mm fixture, 1.25L D ≤;Diameter D between the fixture in 150300mm , 0.9L D ≤;Fixture diameter D is greater than 300mm , 0.6L D ≤.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.References[1] Chen Guofu. Lathe fixture [J]. Mechanical workers. Cold, 2000 (12)[2] Dong Yuming. Yang Hongyu. Fixture design in the common problems [J]. Mechanical workers. Cold, 2005 (1)[3] Liu Juncheng The machine clamps the clamping force in the design process calculations [J]. tool technology, 2007 (6)附录B车床夹具设计分析马飞跃（合肥学院机械工程系，安徽 合肥 230022）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。