Method and apparatus for making cold-pilger-rolled pipe

Abstract

An apparatus for making a cold-pilger-rolled tube has two grooved pilger work rolls rotatable in a roll frame about respective axes to compress a tubular workpiece moving in a travel direction around a mandrel extending in the direction between a nip formed between the grooved rolls and anchored upstream of the nip in a thrust block. An outside diameter of the workpiece is measured downstream in the direction from the rolls as the workpiece passes through the nip, and an actuator engaging one of the rolls relative the other of the rolls shifts it transversely to the travel direction as the workpiece passes through the nip in accordance with the measured outside diameter for maintaining a uniform outside diameter of the workpiece.

1 . In an apparatus for making a cold-pilger-rolled tube having two grooved pilger work rolls rotatable in a reciprocating roll frame about respective axes to compress a tubular workpiece moving in a travel direction against a mandrel extending in the direction between a nip formed between the rolls and anchored upstream of the nip in a thrust block, the improvement comprising:
 means for measuring an outside diameter of the workpiece downstream in the direction from the rolls as the workpiece passes through the nip; and   means for displacing one of the rolls relative the other of the rolls transversely to the travel direction as the workpiece passes through the nip in accordance with the measured outside diameter for maintaining a uniform outside diameter of the workpiece.   
     
     
         2 . The apparatus defined in  claim 1 , further comprising
 control means between the means for measuring and the means for displacing for operating the means for displacing to maintain a uniform outside diameter of the workpiece.   
     
     
         3 . The apparatus defined in  claim 1 , wherein the control means has a memory in which is stored data including a desired outside diameter of the workpiece. 
     
     
         4 . The apparatus defined in  claim 2 , wherein the control means compares the measured outside diameter of the workpiece from the means for measuring with the desired outside diameter and operates the means for displacing to change transverse position of the one roll when a differential between the measured outside diameter and the desired outside diameter exceeds a predetermined limit. 
     
     
         5 . The apparatus defined in  claim 1 , wherein the means for measuring is a laser sensor. 
     
     
         6 . The apparatus defined in  claim 1 , wherein the means for displacing includes an actuator braced between the frame and the one roll. 
     
     
         7 . The apparatus defined in  claim 6 , wherein the actuator is a movable wedge braced between the frame and the one roll. 
     
     
         8 . The apparatus defined in  claim 7 , wherein the actuator further includes a hydraulic cylinder braced between the wedge and the frame. 
     
     
         9 . The apparatus defined in  claim 6 , wherein the actuator is a hydraulic cylinder transversely braced between the one roll and the frame. 
     
     
         10 . The apparatus defined in  claim 6 , further comprising:
 respective backing rolls flanking and engaging the work rolls, at least one of the backing rolls being transversely shiftable by the actuator.   
     
     
         11 . The apparatus defined in  claim 6 , wherein the means for measuring or the means for controlling is mounted away from the frame and is connected to the actuator by a wired or wireless link. 
     
     
         12 . The apparatus defined in  claim 1 , wherein the thrust block is also shiftable relative to the work rolls. 
     
     
         13 . The apparatus defined in  claim 12 , wherein the means for displacing is also connected to the thrust block. 
     
     
         14 . A method of making a cold-pilger-rolled tube, the method comprising the steps of:
 simultaneously moving a workpiece in a travel direction through a nip between two grooved pilger work rolls rotatable in a roll frame about respective axes while pressing the workpiece against around a mandrel extending in the direction through the nip;   measuring an outside diameter of the workpiece downstream in the direction from the rolls; and   displacing one of the rolls relative the other of the rolls transversely to the travel direction in accordance with the measured outside diameter for maintaining a uniform outside diameter of the workpiece.   
     
     
         15 . The method defined in  claim 14 , further comprising the step of:
 processing the measured outside workpiece diameter in a controller and operating at least one actuator connected to the one roll in accordance with the measured outside workpiece diameter.   
     
     
         16 . The method defined in  claim 15 , wherein the outside diameter is measured and the one roll is displaced as the workpiece passes through the nip. 
     
     
         17 . The method defined in  claim 14 , wherein the outside diameter is read with a laser sensor. 
     
     
         18 . The method defined in  claim 14 , wherein the outside diameter is measured all around the workpiece. 
     
     
         19 . The method defined in  claim 14 , wherein for each tube that made or each revolution of the workpiece as it passes through the nip the outside of the workpiece is measured at least 5 times. 
     
     
         20 . The method defined in  claim 14 , further comprising the step of:
 displacing the thrust block and mandrel in or transverse to the travel direction as the workpiece passes through the nip in accordance with the measured outside diameter when same lies outside a predetermined range.