滚动轴承的轴承环和高精度衬套类零件的内孔形状精度,一般都具有较高的圆度要求(如允差<0.5μm)。影响其加工精度的原因,除了机床主轴及磨头系统的稳定性外,工件的夹具也对被加工工件精度产生很大的影响。通常采用三爪卡盘夹紧这类零件的外圆,对内孔进行磨削,往往因为受力和导热不均匀,引起工件变形,使工件内圆几何形状呈多角形。为达到较高的圆度要求,我们采用端面三点等力压紧夹具,实际使用效果较好。其结构形式见附图。夹具结构夹具体1以机床主轴8之短锥部分作为定位,并用螺钉固结成一体。夹具体和定位套9采用H7/k6过渡配合。定位套安装入夹具体内孔后,由机床磨头精磨定位套内孔至使用要求。使用时,将已磨平两端面的工件10装入定位套孔内,压圈12放置在工件端面上,拧紧经调节后的夹紧螺钉15。由于压力传递介质凡士林油受圆柱销11 Rolling bearing rings and high-precision bushing type parts bore shape accuracy, generally have a higher roundness requirements (such as tolerance <0.5μm). Affect the machining accuracy of the reasons, in addition to the stability of the spindle and grinding head system, the workpiece fixture also has a great impact on the accuracy of the workpiece being machined. Usually three-jaw chuck clamping of such parts of the outer circle, the inner hole for grinding, often due to uneven force and thermal conductivity, causing the workpiece deformation, so that the workpiece was polygonal internal geometry. In order to achieve a higher roundness requirements, we use three-point end pressure clamping fixture, the actual use of better. Its structure is shown in the attached drawings. Clamp structure fixture body 1 to the short taper of the machine tool spindle 8 as a positioning, and with screws into one. Clamp body and positioning sleeve 9 with H7 / k6 transition fit. After the positioning sleeve is installed into the inner hole of the clamp, the grinding hole of the positioning sleeve is refined by the grinding machine of the machine to the use requirements. In use, the workpieces 10 with both end surfaces polished are put into the positioning sleeve holes, and the pressing ring 12 is placed on the end face of the work piece to tighten the adjusted clamping screw 15. Due to the pressure transmission medium Vaseline received by the cylindrical pin 11