Butt welding apparatus, butt welding method, and butt welded product

Abstract

Disclosed are a butt welding apparatus, a butt welding method, and a product manufactured by the butt welding method. Two electrode rollers ( 3, 4 ) are disposed on both the front and back sides of a thick sheet member ( 1 ) and on both the front and back sides of a thin sheet member ( 2 ) whose end surfaces ( 1 A, 2 A) are butted. The electrode rollers ( 3, 4 ) are applied with power, melt the butt portion ( 6 ) of the sheet members ( 1, 2 ) with electric resistance heat, and joint the butt portion. Further, the electrode rollers ( 3, 4 ) have a length bridging across the sheet members ( 1, 2 ) and are composed of first portions ( 3 A, 4 A) arranged as small diameter portions on the side of the thick sheet member ( 1 ) and second portions ( 3 B, 4 B) arranged as large diameter portions on the side of the thin sheet member ( 2 ). The first portions ( 3 A, 4 A) come into contact with the thick sheet member ( 1 ) and presses it before the second portions ( 3 B, 4 B) come into contact with the thin sheet member ( 2 ). Thus, the end surface ( 1 A) of the thick sheet member ( 1 ) swells and deforms toward the thin sheet member ( 2 ) and reliably comes into contact with the end surface ( 2 A) of the thin sheet member ( 2 ). As a result, power is applied between the end surfaces ( 1 A, 2 A) even if the end surfaces ( 1 A, 2 A) are not finished by polishing and the like.

1 .- 15 . (canceled)  
   
   
       16 . A butt welded product according to  claim 23 , characterized in that the product forms a part of a vehicle body of a vehicle by being used as an inner panel coupled with an outer panel and the surface on the side without step is disposed as an outward surface facing the outer panel.  
   
   
       17 . A butt welded product according to  claim 16 , characterized in that the inner panel is an inner panel for each door attached to the main portion of the vehicle body by hinges which are coupled with the thick sheet member of the thick and thin sheet members forming the inner panel.  
   
   
       18 . A butt welded product according to  claim 23 , characterized in that the butt welded product is used as a dashboard of a vehicle, the thin sheet member forms an upper side and the thick sheet member forms a lower side, and the surface without step faces the side of a vehicle inside space formed in front of a driver's seat.  
   
   
       19 . (canceled)  
   
   
       20 . A butt welded product according to  claim 23 , characterized in that the product forms a part of a vehicle body of a vehicle by being used as an inner panel coupled with an outer panel, and the surface on the side without step is disposed as an outward surface facing the outer panel.  
   
   
       21 . A butt welded product according to  claim 20 , characterized in that the inner panel is an inner panel for each door attached to the main portion of the vehicle body by hinges which are coupled with the thick sheet member of the thick and thin sheet members forming the inner panel.  
   
   
       22 . (canceled)  
   
   
       23 . A butt welded product comprising two welding sheet members having end surfaces butt welded to one another and a nugget extending into each welding sheet member through the butt welded end surfaces, the end surface of one of the welding sheet members, which abuts against the end surface of the other welding sheet member, being swollen and deformed in a direction towards the other welding sheet member.  
   
   
       24 . A butt welded product according to  claim 23 , wherein the two welding sheet members have different thicknesses.  
   
   
       25 . A butt welded product according to  claim 23 , wherein the two welding sheet members have the same thickness.  
   
   
       26 . A butt welded product according to  claim 23 , wherein the end surfaces of the two welding sheet members are in the same state as when sheared from blanks to manufacture the welding sheet members and not subjected to finish processing.