在成型和定径时运用成组技术，可用一套开口孔型辊、定径辊生产一组外径相近的焊管。

With the grouping technique it is allowed to produce a group of tube sizes with similar O.

youdao

在成型和定径时运用成组技术，可用一套开口孔型辊、定径辊生产一组外径相近的焊管。

With the grouping technique it is allowed to produce a group of tube sizes with similar O.

youdao