磨料电解加工在硬质合金刀具刃口钝化上的应用

Application of abrasive electrochemical machining in carbide tool edge honing

常用机械式刃口钝化存在效率低、工具损耗严重等缺点。利用电化学尖端效应结合磨料去除氧化膜,将磨料电解加工应用于硬质合金刀具钝化,可精确地加工出圆弧形刃口。扫描电镜分析表明,钝化消除刃口微小崩刃缺陷和附近前/后刀面磨削痕迹,表面粗糙度由钝化前0.31μm减小到0.14μm,刃口表面质量明显改善。对刃口附近出现微米级的腐蚀微坑做能谱分析,发现钴由钝化前5.8%减小到0.6%,表明富钴区域优先电解。微坑内存在较多杂质元素K、Cl、Na、N是电解质的残留,表明钝化后应加清洗工序。相同切削用量下的对比钻削实验,磨料电解钝化的钻头刃口磨损量略低于毛刷式钝化的钻头。

The traditional mechanical cutting edge honing has some disadvantages such as low efficiency, tool wear and so on. Using electrochemical tip effect and abrasive to remove oxide film, the abrasive electrochemical machining is applied to passivation of cemented carbide cutters, and arc edges are machined accurately. The SEM result showed that passivation eliminated the micro-chipping and grinding marks near the front/rear edge of the edge, and the surface roughness reduced from 0.31 to 0.14 μm. The surface quality of the cutting edge was improved obviously. The energy spectrum analysis of micro-scale corrosion pits near the edge showed that the Co content decreased from 5.8% to 0.6%, indicating that cobalt-rich areas were preferred to electrolysis. There are many electrolyte residues of impurity elements K, Cl, Na and N in the micropits, indicating that the cleaning process should be carried out after passivation. Drilling tests with the same cutting parameters confirmed that the wear rate of cutting edge with electro-abrasive honing is lower than that of abrasive brushing.