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: 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.

Abstract: The present invention is directed to an extraction device for use in continuous rolling mills for extracting tubes from retaining mandrels. The extraction device includes a frame having three pressure yielding rollers mounted therein. The rollers are normally retained in a fixed position for performing a final reduction on the tubes. However, if a mandrel on which the tube has been rolled accidentally enters the orifice defined by the three rollers, the rollers will yield to the excessive pressure and move away from the center of the frame by an amount corresponding to the maximum diameter of the tube containing the mandrel.

Abstract: The invention relates to a housing for a rolling mill for producing axially bored cylindrical blooms from square bars, the housing being of the kind substantially comprising a pair of cogging rollers having round grooves and associated bearing chocks mounted in the housing, an inlet guide for bearing a square bar to be rolled, an outlet guide for the board, rolled cylindrical bloom, and means for adjustably positioning the inlet guide relative to the rolling axis.