为了提高劳动生产率，保证加工质量，降低劳动强度，需要设计专用夹具。经过

为了提高劳动生产率，保证加工质量，降低劳动强度，需要设计专用夹具。经过与指导老师协商，决定设计第3道工序—钻、扩、粗绞Φ20的孔的钻床夹具。本夹具将用于Z525立式钻床，刀具为Φ18钻头、Φ19.8扩孔钻和Φ20的绞刀。<br>（一）问题的提出<br>本夹具主要用来钻Φ4mm孔及扩Φ6mm的孔，此孔的形位公差和表面要求较高，故加工此孔时Φmm 的外圆柱面和其端面应加工出来，可用来作为此工序的定位面。因此在本道工序，在保证提高劳动生产率，降低劳动强度的同时可以设计选用比较简单的专用夹具。<br>（二）夹具设计<br>1、定位基准的选择<br>由零件图可知，Φ20孔的轴线和Φ45的轴线有同轴度要求，对Φ45的端面面有垂直度要求，其设计基准为Φ45圆柱面的中心线、Φ45的端面。为了使定位误差为0，本设计只选用以Φ45圆柱面为主要定位基面，另选用Φ45的端面为辅助定位基准。为了降低生产成本，本设计选择采用螺旋加紧机构的夹紧的方式。<br>2、切削力及夹紧力计算<br>刀具：高速钢钻头 D=Φ18mm

为了提高劳动生产率，保证加工质量，降低劳动强度，需要设计专用夹具。 经过与指导老师协商，决定设计第3道工序—钻、扩、粗绞Φ20的孔的钻床夹具。 本夹具将用于Z525立式钻床，刀具为Φ18钻头、Φ19.8扩孔钻和Φ20的绞刀。<br>（一）问题的提出<br>本夹具主要用来钻Φ4mm孔及扩Φ6mm的孔，此孔的形位公差和表面要求较高，故加工此孔时Φmm 的外圆柱面和其端面应加工出来，可用来作为此工序的定位面。 因此在本道工序，在保证提高劳动生产率，降低劳动强度的同时可以设计选用比较简单的专用夹具。<br>（二）夹具设计<br>1、定位基准的选择<br>由零件图可知，Φ20孔的轴线和Φ45的轴线有同轴度要求，对Φ45的端面面有垂直度要求，其设计基准为Φ45圆柱面的中心线、Φ45的端面。 为了使定位误差为0，本设计只选用以Φ45圆柱面为主要定位基面，另选用Φ45的端面为辅助定位基准。 为了降低生产成本，本设计选择采用螺旋加紧机构的夹紧的方式。<br>2、切削力及夹紧力计算<br>刀具：高速钢钻头 D=Φ18mm

In order to improve labor productivity, ensure processing quality and reduce labor intensity, special clamps need to be designed. After consultation with the instructor, it was decided to design the drilling machine fixture for the third process - drilling, expanding and roughly reaming Φ 20 holes. The fixture will be used for z525 vertical drilling machine, with the cutter of Φ 18 drill bit, Φ 19.8 reamer and Φ 20 reamer.<br>（1） Questions raised<br>This fixture is mainly used to drill Φ 4mm holes and expand Φ 6mm holes. The shape and position tolerance and surface requirements of this hole are high. Therefore, when processing this hole, the Φ mm outer cylindrical surface and its end face should be machined out, which can be used as the positioning surface of this process. Therefore, in this process, the simple special fixture can be designed and selected while ensuring the improvement of labor productivity and the reduction of labor intensity.<br>（2） Fixture design<br>1. Selection of positioning datum<br>It can be seen from the part drawing that the axis of Φ 20 hole and Φ 45 axis have coaxiality requirements, and the perpendicularity requirements for the end surface of Φ 45. The design basis is the center line of Φ 45 cylindrical surface and the end surface of Φ 45. In order to make the positioning error 0, only Φ 45 cylindrical surface is selected as the main positioning base, and Φ 45 end face is selected as the auxiliary positioning base. In order to reduce the cost of production, this design adopts the clamping method of screw tightening mechanism.<br>2. Calculation of cutting force and clamping force<br>Cutter: high speed steel drill d = Φ 18mm<br>