【正文】 ring has the following:1, the determination of locating elementsPositioning refers to determine the workpiece on the machine (table) have the right process or jig, can usually be interpreted as relative to the workpiece cutting tool or grinding tool of a certain position, to ensure the processing precision of dimension, form and position requirements. So reference [4] in the second chapter introduces the monly used positioning method is: (1) the workpiece with planar location with cylindrical holes (2) the workpiece location outside round surface (3) the workpiece positioning (4) the orientation of workpiece with other surface (5) bination (6) side two holes on the surface of the positioning2, clamping device and the determination of clamping forceClamping refers to artifacts should be fixed after positioning, can withstand gravity in the machining process and cutting force, and the operation of the locating position unchanged. By reference [4] in the third chapter are: (1) the determination of clamping device when the clamping device is an important part of the jig.Should be paid attention to when designing clamping device, to meet the following requirements: 1) should be able to keep the workpiece positioning in the process of stepping up the correct position. 2) size appropriate clamping force. Clamping mechanism should ensure workpiece in machining process does not produce looseness or vibrations, and at the same time to avoid undue distortion and surface damage is generated. And the clamping mechanism general selflocking function. 3) clamping device should be easy to operate, safe, energy saving. 4) the plexity of the clamping device and automation should be adapted to production batch and production way. Should strive to simple, pact structure and design, and try to adopt standardized ponents. (2) determination of clamping forceClamping force includes three elements: size, direction and functional point.Clamping force in the direction of choice in general should follow the following principles: 1) the role of the clamping force direction should be conducive to the accurate positioning of workpiece, and not damage localization. 2) the clamping force direction as far as possible consistent with the direction of the workpiece stiffness big, to reduce the workpiece clamping deformation. 3) clamping force direction should be the same as that of cutting force, gravity of workpiece, to minimize the required clamping force. The point of clamping force options: 1) clamping force point should be on supporting ponents or located in the support element formed by the supporting surface, to ensure the positioning of workpiece has been unchanged. 2) clamping force point should be in the workpiece rigid good parts, in order to reduce clamping deformation of workpiece. 3) clamping force point should be close to processing surface, to reduce the workpiece caused by cutting force turning torque. Clamping force calculations: estimate the clamping force of the general approach is to separate the workpiece as a body, forces, and analyze the effect on the parts again According to the system of force equilibrium conditions to determine the minimum clamping force required to keep the balance of artifacts, the final will be the minimum clamping force multiplied by an appropriate factor of safety, that is to get the required clamping force.Second, the structure of fixture types Boring machine fixture according to its structural characteristics, the use of machine tool and boring position is different, have the following classification method.1. According to the used machine tools category, can be divided into universal boring clamp, multiaxis boring modular machine tool clamp, precision boring machine, and the mon boring machine tool fixture.2. According to clamp the structure characteristics of points, can be divided into vertical and horizontal boring machine jig boring machine fixture, etc.3. According to the boring and sets the location of the distribution, can be divided into the single bearing before guided boring clamp, namely boring set is to be processing the front of the hole。 After the single bearing guided boring fixture.3, clamp design basic requirements 1. Fixture parts processing process to meet the accuracy requirement, especially for the finishing process, should improve the accuracy of jig, appropriately to ensure the size tolerance and position tolerance of workpiece, etc.2. The clamp should meet the requirements of machining productivity.3. The jig operation more convenient and safe.4. Guarantee clamp the certain service life and low manufacture cost.5. To raise the degree of generalization and standardization of fixture element.6. Must have good molding process, so that the fixture manufacturing and maintenanceNote: boring clamp finishing with the focus on the requirements of machining precision, etcFour, fixture design method Mainly is to draw the pattern at the same time, formulate the technical requirements. Should refer to the typical fixture design, on the basis of design scheme according to processing requirements to devise, then through modification, finally determine the structure of the fixture.Five, the fixture design steps Design: 1. Before the fixture design, designers should clear the design task and requirements, according to the task serious investigation and study, to collect the data, and carries on the analysis: (1) collect product detail drawing, assembly drawing, blank drawing, process and procedure and other technical documents, analysis of part of the function, shape, structure, material and technical requirements. (2) the analysis of ponents of the machining process planning, especially the working procedure of semifinished products shape, size, machining allowance, cutting allowance, and the use of technology reference. (3) the analysis process the