Research and Application of Process Combining Backward-extrusion Piercing with Push Bench Drawing+Cross-rolling for Manufacture of Large-sized Seamless Steel Tubes

The combined process involving backward-extrusion piercing and push bench drawing plus crossrolling is flexible,and so suitable for manufacturing high value-added special seamless steel tubes like the large-sized,extra-heavy walled or light-walled ones featuring tight dimensional tolerances and fine surface quality.Compared with the conventional cross-rolling process or the extrusion process,the combined process is rather advanced.This process partially substitutes the new techniques such as cross-rolling/piercing,reeling and sizing of large-sized workpieces for the mandrel mill rolling+rotary expanding process,being a pilot practice in the field of manufacture of large-sized,light wall seamless steel tubes.