1·Secondly there is error between the thread roll angles of thread rolling die and drill rod.
滚丝轮螺纹和钻杆螺纹的螺旋角有误差。
2·The advanced hydraulic system has self-return and drill rod stuck proof implements, which ensure great maneuverability and reliability.
先进的液压系统有自我的回报和钻杆坚持证明实施，确保伟大的机动性和可靠性。
3·Through the project case histories the paper analysed the causes of forming the cast drill rod and an useful protection measure is taken.
该文通过工程实例分析了形成铸钻杆的原因，并采取了有效的防治措施，在施工中降低了事故的发生率。
4·The sales, maintenance and service of rotary drilling rig drill rod;
旋挖钻机钻杆的销售、维修、服务；
5·Equipped with hydraulic holder and hand powered unscrewer, to untighen the drill rod easily.
附设液压夹持器，并配以手动御扣装置，使拆御钻杆更方便。