Lead-in guideway for a rolling and punching machine

Abstract

The present invention is directed to a pressure and piercing mill for converting a square bar, coming from a bar rolling mill or directly from a continuous casting plant, into a round, axially pierced blank. The basic machine includes inlet and outlet guide members which are positioned adjacent to a pair of rolling cylinders having round grooves and a mandrel which extends along the rolling axis and from the outlet side of the guide members. In addition, a pushing member is provided for driving the square bar through the inlet and outlet guides, the rolling cylinders and against the piercing bit. The present invention is directed to an improved inlet and outlet guide members which ensure that the blank is accurately centered on the rolling and piercing axis during its travel through the pressure and piercing mill. This improved centering of the square bar is achieved by providing an inlet guide which includes a rectilinear tunnel having a square cross section and made of four linear groups extending parallel to the rolling axis and held independently of one another by a stationary frame. Each linear group comprises a longitudinal, rigid, internal, flat rectilinear wall. At least two consecutive linear groups are movable in a direction perpendicular to the rolling axis when a predetermined pressure is exerted on the flat rectilinear walls of the consecutive linear groups from within the rectilinear tunnel.