攻丝前钻孔 meaning in Chinese

vorbohren rough-bore

Subland twist drills with cylindrical shanks for holes prior to tapping screw threads
攻丝前钻孔用圆柱柄阶梯麻花钻
Subland twist drills with morse taper shanks for holes prior to tapping screw threads
攻丝前钻孔用莫氏锥柄阶梯麻花钻
Subland twist drills for holes prior to tapping screw threads . part 1 : the types and dimensions for subland twist drills with parallel shanks
攻丝前钻孔用阶梯麻花钻第1部分:直柄阶梯麻花钻的型式和尺寸
Subland twist drills for holes prior to tapping screw threads . part 1 : the types and dimensions for subland twist drills with morse shanks
攻丝前钻孔用阶梯麻花钻第2部分:莫式锥柄阶梯麻花钻的型式和尺寸