Explanation

Abbreviated as PPM. The perforation method is different from oblique breast perforation and vertical perforation. PPM uses a pressure pusher to push the hot square billet into the horizontal roll pass, and then it is rolled into a hollow shell by plug rolling. This piercing mill can use continuous casting square billet as raw material. The metal yield is 7% higher than that of continuous casting square billet milk round tube billet. It can rolling up to 12m long tubes with good internal surface quality. The piercing deformation is in the state of three-way compressive stress, which can produce high alloy steel pipes that are difficult to be pierced by ordinary skew rolling piercing mill. Its power consumption is low and its output is high. However, the eccentricity of capillary wall thickness during perforation is too large, and can generally only be controlled at 12% -15%. It is reduced to ± 5% -6% after extension, and increased to ± 10% after continuous rolling, more than 50% larger than skew rolling piercing. In addition, there are strict requirements for the size deviation and flatness of continuous casting billets, otherwise defects may occur and pressure piercing cannot be carried out.

Classification