Metal pipe straightening method, straightening roller, and manufacturing device

Abstract

A straightening method is presented where a concave roller, which has a roller caliber and in which the projection of the roll caliber forms an arc with respect to the cross section of a pipe. The projection arc radius can freely be changed by adjusting the angle between the roller axis and the axis line of the pipe. A plurality of concave rollers are arranged on the outer surface of the metal pipe in the circumferential direction, and rolling is applied on the outer diameter of the pipe while revolving these rollers about the pipe axis.

1 . A metal pipe straightening method comprising: 
 revolving a straightening roller group about the axis of a metal pipe to apply pressure to the metal pipe to straighten the outer circumference of the metal pipe,    wherein said straightening roller group includes:    a plurality of concave rollers with a roller caliber to be arranged in the circumferential direction of the outer surface of the metal pipe,    the roller caliber of the concave roller, which is made to contact the metal pipe, having a structure in which parts of the projection of the roller surfaces on the cross-section surface of the metal pipe are on the same circumference of the metal pipe, and    the radius of the projection arc can be adjusted according to the angle of inclination of the roller with respect to the axial line of the pipe and the position in the radial direction of the pipe.    
   
   
       2 . A metal pipe straightening method comprising: 
 revolving about the axis of a metal pipe a plurality of straightening roller groups arranged in a axial direction of the metal pipe to apply pressure to the metal pipe to straighten the outer circumference of the pipe    wherein each of the straightening roller groups include:    a plurality of concave rollers with a roller caliber, which are arranged in the circumferential direction of the outer surface of the metal pipe,    the roller caliber of the concave roller, which contacts the metal pipe, having a structure in which parts of the projection of the roller surfaces on the cross-section surface of the metal pipe are on the same circumference of the metal pipe, and    the radius of the projection arc can be adjusted according to the angle of inclination of the roller with respect to the axial line of the pipe and the position in the radial direction of the pipe.    
   
   
       3 . The metal pipe straightening method according to  claim 2 , wherein a pipe axial pass line of the whole metal pipe, which passes through the plurality of straightening roller groups, has an eccentric relationship to the axis of the metal pipe in the position which is the geometrical center of the arrangement of the rollers, which form any of the straightening roller groups and which are the center of revolution thereof, and deformation by bending occurs in the longitudinal direction of the metal pipe, which passes through the roller groups in order to increase the straightness of the pipe in the axial direction.  
   
   
       4 . The metal pipe straightening method according to  claim 2 , wherein the geometrical center of the arrangement of the rollers, which form any of the straightening roller groups, has an eccentric relationship with the center of revolution of that roller group, and deformation by bending occurs in the longitudinal direction of the metal pipe, which passes through the roller groups in order to increase the straightness of the pipe in the axial direction.  
   
   
       5 . A metal pipe straightening roller, which is used in the metal pipe straightening method according to  claim 1 , wherein the roller caliber of concave rollers contacting the metal pipe is constructed such that parts of the projection of the surfaces of the rollers on the cross-section surface of the metal pipe are on the same circumference of the metal pipe, and the radius of the projection arc can be adjusted according to the angle of inclination of the roller with respect to the axial line of the pipe and the position of the rollers in the radial direction of the pipe.  
   
   
       6 . A manufacturing apparatus for a metal pipe comprising: 
 an apparatus which continuously produces a metal pipe from metal strapping in a forming process which uses a forming roller, forming shoe, or both, and    an apparatus which straightens the metal pipe after production in a sizing process, wherein the metal pipe straightening method according to  claim 1  is used in the sizing process.    
   
   
       7 . A manufacturing apparatus for a metal pipe comprising: 
 an apparatus which continuously produces a metal pipe from metal strapping in a forming process which uses a forming roller, forming shoe, or both, and    an apparatus which straightens the metal pipe after production in a sizing process, wherein the metal pipe straightening method according to  claim 2  is used in the sizing process.    
   
   
       8 . A metal pipe straightening roller which is used in the metal pipe straightening method according to  claim 2 , wherein the roller caliber of concave rollers contacting the metal pipe is constructed such that parts of the projection of the surfaces of the rollers on the cross-section surface of the metal pipe are on the same circumference of the metal pipe, and the radius of the projection arc can be adjusted according to the angle of inclination of the roller with respect to the axial line of the pipe and the position of the rollers in the radial direction of the pipe.