最近,西德一家公司发明了这种游动芯棒,适于拉制薄壁管材和一般的管材,特别适于拉制诸如铝及铝合金那样的粘附性能强的材料。用常规的芯棒拉制上述焊接管时,管材的内表面得到延伸,焊缝突起处从管材的内表面上被刮下。同时大部分的润滑剂也被刮下的毛刺带走,使减壁区只存在极微量的润 Recently, a company in West Germany invented this swimming mandrel, which is suitable for drawing thin-walled pipes and pipes in general and is especially suitable for drawing highly adherent materials such as aluminum and aluminum alloys. When the above-mentioned welded pipe is drawn with a conventional mandrel, the inner surface of the pipe is extended and the weld bead is scraped off from the inner surface of the pipe. At the same time most of the lubricant is also scraped away the burr away, so that there is only a very small amount of run-off Run