left-hand square thread是什么意思

用法例句

Intorduced to develop hot rolled left screw bar ofΦ18、Φ20、Φ22that was needed by buyer.

介绍了在轧钢厂二车间开发顾客需要的Φ18、Φ20、Φ22的热轧左旋螺纹钢。

Helical fissures are observed on the surface of steel Cr12MoV cold work rolls after rough grinling by use of magnaflux inspection and metallographic examination.

采用磁粉探伤、化学分析及金相检验等方法对Cr12MoV钢冷轧工作辊粗磨后表面呈现的螺旋形波纹进行了检测分析。