Abstract: A 2-roll piercing mill for producing hollow blocks from a rolled material comprising high alloy steels has guide tools for the rolled material. The guide tools are arranged for closing a reforming zone of the piercing mill transversely with respect to the rolling axis as the hollow block is pierced. In this arrangement, each of the guide tools includes a base body made of a carrier material and a working face made of a material that has antiadhesive properties with respect to high alloy steels and high hot strength. Prior to the piercing operation, the temperature of either the working face or the entire guide tool is raised above room temperature to avoid high thermal stresses.

Abstract: A process for producing a hollow billet for producing tubing for antifriction bearings includes massively reducing a bloom in a three-roll rotary piercing mill and subsequently piercing the reduced bloom in a three-roll rotary piercing mill. The reducing and piercing may be performed in one-pass through the three-roll rotary piercing mill. The reducing and piercing steps may also be performed in separate passes through the same mill or through two separate mills.

Abstract: A method of calibrating and orienting forming rollers of an Assel-type rolling mill, and more particularly, of calibrating an Assel mill for rolling thin-walled tubes of pre-pierced hollow bodies about a mandrel, using at least three generally conical rollers that are circumferentially spaced about the mandrel. The orientation of each forming roller is adjusted so as to position the roller inclination relative to the mandrel axis of roll by an expansion angle .alpha. of approximately 7.degree. to 30.degree.. Each forming roller is also adjustably oriented so that its smoothing part relative to the mandrel axis of roll defines a transport angle .gamma. of approximately 7.degree. to 17.degree.. In further accordance with this invention, each forming roller is configured so as to have an opening angle .beta. of approximately 4.degree. to 15.degree..

Abstract: The invention relates to a process for reducing the outside diameter and wall thickness by rolling a cylindrical hollow ingot the front part of which is fed into an Assel rolling mill, in which connection, in front of the Assel rolling mill as seen in the direction of feed, a device is provided for reducing the diameter and/or wall thickness of the rear end part of the hollow ingot threaded onto a mandrel rod. In this process, the prereduction rolls are slowly and continuously pressed against the ingot at a predetermined point near the end of the ingot to produce a conically reduced end portion.