Plug rolling process
The plug rolling process is a rolling process for the production of seamless steel tubes .
Plug rolling plants can largely be traced back to Stiefel. Boot rolling mills originally consisted of piercing piercing mills, stretching piercing mills, Stiefelscher plug rolling mills and at least one smoothing mill in front of a downstream reducing mill as a finishing stage. Because a high temperature loss occurred on the tube after the many process stages from piercing to reducing rolling mill, the tubes were usually reheated to reducing rolling temperature in a specially designed furnace after the smooth rolling.
The original Stiefel plug mill had rolls with several gauges cut next to each other. Single-caliber plug rolling systems were later developed because the multi-caliber rolls led to inaccuracies in the rolled product due to the deflection.
In plug rolling mills, a hollow block is rolled out over a stationary plug supported on a rod, preferably in two to three passes, to form a shell. After each pass, the billet is pulled from the bar against the rolling direction by a driving device and turned by 90 degrees and fed to the next pass. The stoppers are changed after each stitch.
literature
About the punching process in the boot rolling mill with special consideration of the stress and behavior of the hole plug - 1929 by Körber Friedrich and Simoneit Karl