Abstract: A device for locking and releasing the mandrel-holding carriage of a piercing pressure mill, the device comprising at least one lever having an end pivoted to a horizontal pivot perpendicular to the mandrel axis, the other end of the lever being free and removably engaging an abutment formed in the carriage, and at least one substantially toggle mechanism having one end pivoted to the lever which cooperates with a means for actuating the mechanism to form a double toggle for angularly moving the lever around its pivot axis from a position in which its free end engages the abutment to a position in which its free end is completely released from the abutment.

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.

Abstract: A device for controlling the speed of a mandrel in a continuous retained-mandrel rolling mill, such device comprising a rod having a double rack provided at one end with a means for removably securing an end of a mandrel and a number of pinions engaging the rack on the rod, each pinion being driven in rotation by a corresponding motor-driven shaft which, via respective clutches is connected to a motor and speed-reducing group provided with a brake for each motor-driven shaft. Further, the device includes a second set of pinions engaging the rack on the rod, each pinion being driven in rotation by a corresponding motor and speed-reducing group provided with a brake.