图1所示的工件,要求精确地加工出与孔A相平行的凹槽B。这一工作可采用图2所示的塑料夹具在铣床上进行。这个夹具一次可加工四个工件。工件依靠它已钻好的孔A定位在中心插销1上;插销1是装在两个轴承座2内,这两个轴承座用螺钉分别固定在底座上。另外在底座3上还固定有一个夹紧框架,它是由夹紧横梁4、中介件5和夹紧元件6组成的。在夹紧横梁4上装有压力支承 The workpiece shown in FIG. 1 requires that the groove B parallel to the hole A be accurately machined. This work can be carried out on a milling machine using the plastic clamp shown in Figure 2. This fixture can process four workpieces at a time. The workpiece is positioned on the center pin 1 by means of the hole A it has drilled; the pin 1 is mounted in two bearing blocks 2, which are each fastened to the base with screws. In addition, a clamping frame is also fastened to the base 3 and consists of a clamping beam 4, an intermediate piece 5 and a clamping element 6. The clamping beam 4 is equipped with pressure support