Tomáš Perna, Petr Unucka, Marek Vindyš, Jaroslav Pindor
Materiálový a metalurgický výzkum s.r.o.
The purpose of the submitted invention is to optimize piercing of semi-products used in seamless tube production in the Mannesmann type piercing mill through the application of a new support cylinder (drilled charge is unacceptable – it would not be piercing). This task extensively solves the piercing mill support cylinder for hollow billet production through its skew rolling between two working piercing rolls with skewed axes and conically shaped surfaces (two truncated cones), when the essence of the invention rests in the fact that the external shape of the support cylinder is convex. The support cylinder's convex shape, as compared to the traditional conically shaped cylinders, significantly enhances the transfer of the working piercing rolls' impacts on the billet centre. It also improves the conditions of purchase and power and strength piercing parameters.