岩心管（套管）接头两端螺纹的同轴度和圆柱度对于保证钻孔质量，减少孔内事故有一定影响。为提高其加工精度，我们试制成功了“重锤式自动夹紧卡具”。经近二年的使用，效果很好，提高了两端螺纹的同轴度，保证了圆柱度，减轻了劳动强度，提高了工作效率。 The concentricity and cylindricity of the threads at both ends of the core tube (sleeve) joint have certain influence on the quality of the drilled hole and the reduction of accidents in the hole. In order to improve its processing accuracy, we successfully produced a “hammer automatic clamp fixture.” After nearly two years of use, the effect is very good, the coaxiality of both ends of the thread is improved, the cylindricity is ensured, the labor intensity is reduced, and the working efficiency is improved.