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印制电路板材机械钻孔加工对硬质合金微钻要求极高,目前硬质合金微钻结构设计局限于螺旋角、芯厚、顶角、沟幅比、硬质合金晶粒度、晶粒结构等优化手段,印制电路板机械钻孔领域对提高硬质合金微钻的加工时孔位精度已经面临瓶颈。本研究设计了一种区别于传统双螺旋槽微钻的新型微钻结构,包含了短排屑槽、长排屑槽及连通槽将长短排屑槽连通设计。该设计在保证了硬质合金微钻正常切削性能和孔位精度的同时,提高了硬质合金微钻的钻体刚度。利用ANSYS有限元分析,在相同切削力加载情况下,新结构硬质合金微钻钻削时钻尖的径向位移量明显减小。经钻削实验验证,该新型微钻相较于传统硬质合金微钻钻削印制电路板背面孔位精度CPK值可提高1倍。
Mechanical drilling of printed circuit board is very demanding for carbide micro-drilling. At present, the design of micro-micro-hard diamond structure is limited to helix angle, core thickness, apex angle, groove width ratio, grain size of cemented carbide, Structure and other optimization methods, printed circuit board mechanical drilling holes to improve the accuracy of carbide micro-drilling processing has been facing a bottleneck. This study designed a new type of micro-drill structure which is different from the traditional double helix groove micro-drill, which includes short chip flute, long chip flute and connecting flute to connect long flute and short flute. The design improves the rigidity of hard alloy micro-drills while ensuring the normal cutting performance of microhardness and hole accuracy. With the finite element analysis of ANSYS, the radial displacement of the drill tip is obviously reduced under the condition of the same cutting force loading. The drilling experiments show that the new micro-drilled drill can improve CPK value by a factor of two compared with that of the conventional hard micro-drilled drill PCB.