Tube production method, heat-exchange tube produced by the method and heat exchanger using the heat-exchange tube

Abstract

A method of producing a tube which has a tube body portion constituting an outer hull of flow passages, and flow passage dividers for dividing the flow passages, comprising a roll forming process to form the tube, a cutting process to cut the tube to a predetermined length after the roll forming process, and a brazing process to braze the tube contact portions of the flow passage dividers to the inner surface of the tube body portion after the cutting process. The cutting process forms a slit in the tube, and so as to concentrate a stress on the slit, thereby to cut the tube starting from the slit. The slit is formed in only the tube body portion between the tube body portion and the flow passage dividers or formed ranging from the tube body portion to the tube contact portions of the flow passage dividers.

1 . A method of producing a tube which has a tube body portion constituting an outer hull of a flow passage, and a flow passage divider for dividing the flow passage, comprising: 
 a roll forming process to form the tube,    a cutting process to cut the tube to a predetermined length after the roll forming process, and    a brazing process to braze a tube contact portion of the flow passage divider to an inner surface of the tube body portion after the cutting process,    wherein:    in the cutting process, a slit is formed in the tube so as to concentrate a stress on the slit, thereby cutting the tube from the slit as a starting point; and    the slit is formed in one of only the tube body portion and a portion ranging from the tube body portion to the tube contact portion.    
   
   
       2 . (canceled)  
   
   
       3 . The method of producing a tube according to  claim 1 , wherein the slit is formed by moving a cutter blade in parallel to a surface of the tube.  
   
   
       4 . The method of producing a tube according to  claim 1 , wherein the slit is formed by moving a disk cutter in parallel to a surface of the tube.  
   
   
       5 . The method of producing a tube according to  claim 1 , wherein the tube is pulled in a longitudinal direction to concentrate the stress on the slit.  
   
   
       6 . The method of producing a tube according to  claim 5 , wherein: 
 the roll forming process and the cutting process are performed while conveying the tube at a first conveying velocity in the roll forming process and a second conveying velocity in the cutting process continuously,    the tube is pulled in the longitudinal direction with a feed roller disposed on a downstream side of the slit in a conveying direction, and    the second conveying velocity is set to be faster than the first conveying velocity.    
   
   
       7 . The method of producing a tube according to  claim 5 , wherein: 
 the roll forming process and the cutting process are performed while conveying the tube continuously, and    the tube is pulled in the longitudinal direction by holding the tube at an upstream and a downstream sides of the slit in a conveying direction by a pair of clamps.    
   
   
       8 . The method of producing a tube according to  claim 1 , wherein said cutting step includes a step of applying a load to the tube in a direction different from a longitudinal direction thereof.  
   
   
       9 . The method of producing a tube according to  claim 8 , wherein said load is applied with a feed roller disposed offset with respect to the longitudinal direction of the tube; and 
 the tube passes through the feed roller after the slit is formed.    
   
   
       10 . The method of producing a tube according to  claim 8 , wherein said load is applied while the tube is oscillated.  
   
   
       11 . The method of producing a tube according to  claim 1 , wherein the tube has a flat shape and a thickness of 0.8 to 1.7 mm.  
   
   
       12 . The method of producing a tube according  claim 1 , wherein the tube body portion has a thickness of 0.15 to 0.25 mm.  
   
   
       13 . The method of producing a tube according to  claim 1 , wherein the flow passage divider includes a bead having a top brazed to the inner surface of the tube body portion.  
   
   
       14 . The method of producing a tube according to  claim 1 , wherein the flow passage divider includes an inner fin separate from the tube body portion.  
   
   
       15 . The method of producing a tube according to  claim 14 , wherein the inner fin has a corrugated shape and a top brazed to the inner surface of the tube body portion.  
   
   
       16 . The method of producing a tube according to  claim 14 , wherein the inner fin has a width of 0.3 to 1.4 mm.  
   
   
       17 . The method of producing a tube according to  claim 14 , wherein the inner fin has a thickness of 0.05 to 0.10 mm.  
   
   
       18 . The method of producing a tube according to  claim 14 , wherein the inner fin has the corrugated shape having a pitch of 0.6 to 2.0 mm.  
   
   
       19 . A heat-exchange tube, which is produced by the method according to  claim 1 .  
   
   
       20 . A heat exchanger comprising the heat-exchange tube according to  claim 19.