Circular rolling mill and rolling method using such a rolling mill

Abstract

A circular rolling mill includes a main chassis, a radial stand and at least one axial stand. The radial stand includes a roller and a mandrel. The axial stand includes an auxiliary chassis and tapered rollers. The mandrel is supported by an upper mandrel holder and selectively engaged with a lower mandrel holder. Each mandrel holder is integral in translation along a longitudinal axis of the main chassis, with at least one drive bar parallel to the longitudinal axis. The movement of the mandrel holders is controlled by a movement system located on the same side of the shaping roller as the mandrel. The auxiliary chassis slides along its longitudinal axis on the drive bars, which pass all the way through it. A mechanism moves the auxiliary chassis relative to the drive bars in translation parallel to the longitudinal axis.

1 . A circular rolling mill for shaping annular workpieces, comprising:
 a main chassis;   a radial stand comprising:
 a shaping roller for shaping an outer radial face of a workpiece to be rolled; and 
 a mandrel for shaping an inner radial face of the workpiece to be rolled, supported by an upper mandrel holder and selectively engaged in a lower mandrel holder, each of the mandrel holders being integral, in translation along a longitudinal axis of said main chassis, with at least one drive bar parallel to the longitudinal axis of said main chassis, movement of the mandrel holders parallel to the longitudinal axis of said main chassis being controlled by a movement system located on the same side of said shaping roller as the mandrel; 
   at least one axial stand, comprising:
 an auxiliary chassis slidably mounted, parallel to the longitudinal axis of said main chassis, on the drive bars of the mandrel holders, which pass all the way through it; and 
 upper and lower tapered rollers for shaping lower and upper radial faces of the workpiece to be rolled; and 
   a mechanism for translating said auxiliary chassis relative to the drive bars, parallel to the longitudinal axis of said main chassis.   
     
     
         2 . The rolling mill according to  claim 1 , wherein a drive bar movement system is mounted on said main chassis on the side of said auxiliary chassis opposite the mandrel holders, the at least one drive bar extends between the movement system and the mandrel holders, and said auxiliary chassis is provided with openings for the at least one drive bar to pass through and for guiding movement of said auxiliary chassis on the at least one drive bar. 
     
     
         3 . The rolling mill according to  claim 1 , wherein each mandrel holder is integral with two drive bars, distributed on either side of a median longitudinal plane of the rolling mill, and wherein said movement mechanism synchronizes movement of said auxiliary chassis along the two drive bars of one of the mandrel holders. 
     
     
         4 . The rolling mill according to  claim 3 , wherein the drive bars, with respect to which said movement mechanism synchronizes movement of said auxiliary chassis, are integral with the lower mandrel holder. 
     
     
         5 . The rolling mill according to  claim 3 , wherein said movement mechanism comprises a frame mounted on the two drive bars and immobilized in translation along the longitudinal axis of said main chassis on these two drive bars, as well as members for driving said auxiliary chassis along the drive bars, relative to the frame. 
     
     
         6 . The rolling mill according to  claim 5 , wherein said frame is provided with two holes for the longitudinal bars on which it is mounted and immobilized to fit through. 
     
     
         7 . The rolling mill according to  claim 5 , wherein said frame supports a motor for moving said auxiliary chassis along the drive bars and members for transmitting movement between the motor and said auxiliary chassis. 
     
     
         8 . The rolling mill according to  claim 7 , wherein the motion transmission members comprise a belt and two parts of ball-screw systems, a belt and two parts of nut-and-screw systems or two parts of rack-and-pinion systems. 
     
     
         9 . The rolling mill according to  claim 5 , wherein said frame carries at least one actuator for moving said frame and said auxiliary chassis away from each other parallel to the longitudinal axis of said main chassis. 
     
     
         10 . The rolling mill according to  claim 1 , wherein an axial stand and a mandrel are provided on each side of said shaping roll, along the longitudinal axis of said main chassis, wherein said auxiliary chassis of each radial stand is slidably mounted, parallel to the longitudinal axis of said main chassis, on the drive bars of the mandrel holders located on the same side, which pass all the way through it, and wherein the circular rolling mill further comprises two mechanisms for moving said auxiliary chassis in translation relative to the drive bars, parallel to the longitudinal axis of said main chassis. 
     
     
         11 . A method for rolling an annular workpiece by means of a rolling mill according to  claim 1 , comprising:
 shaping the radial outer and inner faces of the annular workpiece, by means of the shaping roller and mandrel, and the lower and upper axial faces, by means of the lower and upper tapered rollers; and   adjusting, as a function of a diameter of the annular workpiece being rolled, a distance between the mandrel and a rear edge of the tapered rollers by actuating the mechanism for moving the auxiliary chassis along the drive bars.