The mechanical properties and metallographic structures of the friction welded drill rod and the hot upset forged drill rodpipe are compared.
本文叙述了这种钻杆的焊接性，并与采用热镦粗工艺生产的钻杆管体金相组织和机械性能进行了对比。
2
The axial flotation of chuck plays an important role in the protection of rodpipe threads and prevention of rodpipe stripping or cutterhead from dropping during the process of raise boring.
在天井钻进过程中，卡盘的轴向浮动对保护钻杆螺纹和防止钻杆脱扣、刀头坠落等方面具有重要作用。
3
Next to it a boy leaned against the railings, his rod and line dangling out over the floating garbage and the stream of brown, stinking waste which trickled from a pipe in the wall below.