Method for drawing metallic tube

Abstract

In a method for drawing a tube blank while supplying lubricant to an inner surface of the tube blank from a discharge opening of a rod, the lubricant is adhered appropriately to the inner surface both in the circumferential direction of the tube blank and in the longitudinal direction thereof without using any application member such as a core. While drawing a metal tube blank 2 by passing between a die 10 for shaping an outer surface and a plug 11 for shaping an inner surface, the lubricant L is discharged intermittently from a discharge opening 21 provided in an outer peripheral surface of a rod 20 supporting the plug 11 toward an upper region 40 of the tube blank 2 positioned higher than the center of the tube 2 in the up-and-down direction to thereby make the lubricant adhere to a portion of the inner surface of the tube 2 including the highest position P 1 of the inner surface of the tube 2.

1 . A method for drawing a metal tube blank,
 while drawing the metal tube blank between a die for shaping an outer surface of the tube blank and a plug for shaping an inner surface of the tube blank, intermittently discharging lubricant through a discharge opening formed in a rod supporting the plug toward an upper region of the tube blank positioned higher than a center of the tube blank in an up-and-down direction to apply the lubricant to a portion of the inner surface of the tube blank including the highest position of the inner surface of the tube blank.   
     
     
         2 . The method for drawing a metal tube blank as recited in  claim 1 , wherein the lubricant is discharged intermittently in a manner such that a discharge amount of the lubricant is gradually increased. 
     
     
         3 . The method for drawing a metal tube blank as recited in  claim 1 , wherein the discharge opening is formed in an outer peripheral surface of a hollow rod. 
     
     
         4 . The method for drawing a metal tube blank as recited in  claim 1 , wherein the lubricant is discharged toward a region of the inner surface of the tube blank positioned within a center angle of 30° at both sides in a circumferential direction from a highest position of the inner surface of the tube blank. 
     
     
         5 . The method for drawing a metal tube blank as recited in  claim 1 , wherein the lubricant is discharged forwardly of the discharge opening. 
     
     
         6 . The method for drawing a metal tube blank as recited in  claim 1 , wherein the lubricant is discharged from a nozzle provided on a periphery of the discharge opening. 
     
     
         7 . An apparatus for drawing a metal tube blank by passing the metal tube blank between a die for shaping an outer surface of the tube blank and a plug for shaping an inner surface of the tube blank, comprising:
 a discharge opening configured to discharge lubricant, the discharge opening being opened in an outer peripheral surface of a hollow rod supporting the plug and provided only in a region of the tube blank higher than a center of the rod in an up-and-down direction; and   a discharge control device configured to intermittently discharge the lubricant and suspend the discharge of the lubricant during the drawing of the tube blank.