过去,我厂加工泡沫塑料上的φ3.5×100的深孔,曾采用标准麻花钻。由于材料的特点,因而加工比较困难(切屑不易切掉,排屑也很难),经常出现孔不圆度大和孔不通的现象,无法满足生产需要。针对以上情况,后来我们改进了麻花钻的切削部分,采用三尖钻(附图),结果加工出来的孔圆整、光滑,既提高了生产效率,又节省了人力,符合了图纸要求。三尖钻钻心部分缩小,锋角2K= In the past, my factory processing deep holes in the φ3.5 × 100 foam, had used a standard twist drill. Due to the characteristics of the material, it is difficult to process (chips are not easy to cut off, chip evacuation is also very difficult), often the phenomenon of large hole non-roundness and hole barrier can not meet the production needs. In view of the above, we later improved the cutting part of the twist drill, using a tipped drill (with photos). The resulting hole was rounded and smooth, which not only improved the production efficiency but also saved manpower and met the requirements of the drawings. Triangle drilling part of the center to reduce the front angle 2K =