机械密封环上游泵送槽凸模压制脱模工艺试验

为了解决凸模压制碳化硅密封环泵送槽时存在的黏模问题,从模具结构、脱模剂种类选择、加压及卸压速度等方面,运用单因素分析法,在液压成型机上开展大量工艺试验,以优化工艺参数组合.研究结果表明：螺旋小块的脱模斜度和过渡圆角对脱模效果和脱模后密封环的形貌影响较大,脱模斜度为11°～15°、下端面过渡圆角半径为0.1～0.2mm时最佳.根据脱模剂性质和试验结果,最终选择自主研制的2种组合方式,即固体润滑剂二硫化钼和凡士林混合,以及锂基润滑脂和抗磨液压油混合.前者脱模后密封环的形貌较好但涂抹过程较烦琐,且成功率偏低,后者反之.加压速度及保压时间对脱模效果无明显影响,但卸载速度的影响较大,当卸载速度为2～5MPa/s时脱模效果最佳.另外,根据碳化硅粉料的特点及泵送槽的形貌要求分析了其他脱模剂不能满足使用要求的原因.

Experimental research on technique of demolding with punch pressing of upstream pumping grooves on sealing rings

To solve the problem of existing sticky mold in punch pressing upstream pumping grooves on sealing rings of SiC,the study was carried out in the aspects of mold structure,selection of mold release agent,speed of compression and depressurization,et al.The single factor analysis method was used,and lots of test with hydraulic forming machine was conducted for parameters optimization.The results show that the most available structure of mold is a draft angle of 11°- 15°on the two sides of the small spiral pieces with a radius of transition fillet with 0.1-0.2 mm on the areas of the bottom corners.Two kinds of combinations were chosen on the selection of mold release agent with their properties and experimental results,one is the combination of molybdenum disulfide of solid lubricant and vaseline,and the other is the combination of lithium base grease and anti-wear hydraulic oil.The appearance of former method is better than latter one,but the process of application is more complicated while the productivity is lower.Pressing speed and holdup time hardly impacts demolding,while depressurization rate has obvious impacts.The optimum depressurization rate is 2- 5 MPa/s.In addition,according to the property of SiC and appearance of pumping grooves,the reasons that other kinds release agent cannot meet the requirements were analyzed.