螺纹前打孔数据

螺纹前打孔螺纹尺寸 钻头直径 下孔径 最小直径 最大直径
3 × 0.5 2.5 2.59 (75%) 2.459 2.599
4 × 0.7 3.3 3.39 (80%) 3.242 3.422
5 × 0.8 4.2 4.31 (80%) 4.134 4.334
6 × 1.0 5 5.13 (80%) 4.917 5.153
8 × 1.25 6.8 6.85 (85%) 6.647 6.912
10 × 1.5 8.5 8.62 (85%) 8.376 8.676
12 × 1.7 10.3 10.40 (85%) 10.106 10.441
14 × 2.0 12 12.2 (85%) 11.835 12.210
16 × 2.0 14 14.2 (85%) 13.835 14.210
18 × 2.5 15.5 15.7 (85%) 15.294 15.744
20 × 2.5 17.5 17.7 (85%) 17.294 17.744
22 × 2.5 19.5 19.2 (85%) 19.294 19.744
24×3.0 21 21.2（85%） 20.752 21.252