Press forming machine and method for manufacturing press-formed product

Abstract

A press forming machine includes a holding structure configured to hold a workpiece, and a metallic die for press forming the workpiece. The workpiece is a member made by joining a first steel plate and a second steel plate together by butt welding. The butt welding is a welding of an end face of the first steel plate and an end face of the second steel plate at a boundary between the first steel plate and the second steel plate. The holding structure is configured to hold a first region including both the first steel plate and the second steel plate adjacent to the boundary as a specific region in the workpiece, and not to hold a second region that is farther from the boundary than the first region and includes at least one of the first steel plate and the second steel plate adjacent to the first region.

What is claimed is: 
     
         1 . A press forming machine comprising:
 a holding structure configured to hold a workpiece; and   a metallic die for press forming the workpiece,   the workpiece being a member in which a first steel plate and a second steel plate are joined together by butt welding,   the butt welding being a welding of an end face of the first steel plate and an end face of the second steel plate at a boundary between the first steel plate and the second steel plate,   the holding structure being configured to hold a first region including both the first steel plate and the second steel plate adjacent to the boundary as a specific region in the workpiece, and not to hold a second region that is farther from the boundary than the first region and includes at least one of the first steel plate and the second steel plate adjacent to the first region.   
     
     
         2 . The press forming machine according to  claim 1 , wherein
 the holding structure holds the workpiece along the boundary.   
     
     
         3 . The press forming machine according to  claim 1 , wherein
 the holding structure is configured to hold an end of a weld line, which is a butt-welded portion of the workpiece.   
     
     
         4 . The press forming machine according to  claim 1 , wherein
 the first steel plate and the second steel plate differ from each other in at least one of plate thickness and strength.   
     
     
         5 . The press forming machine according to  claim 4 , wherein
 the first steel plate and the second steel plate have different plate thicknesses,   the holding structure has a step corresponding to a difference in plate thickness between the first steel plate and the second steel plate so as to be able to hold surfaces of both the first steel plate and the second steel plate, and   the step is provided along a plate thickness direction of the first steel plate and the second steel plate.   
     
     
         6 . The press forming machine according to  claim 1 , wherein
 the first region is smaller than the second region.   
     
     
         7 . A method for manufacturing a press-formed product, the method comprising:
 holding a workpiece, the workpiece being a member in which a first steel plate and a second steel plate are joined together by butt welding; and   press forming at least one of the first steel plate and the second steel plate in its plate thickness direction,   the butt welding being a welding of an end face of the first steel plate and an end face of the second steel plate at a boundary between the first steel plate and the second steel plate,   the holding the workpiece including holding a first region including both the first steel plate and the second steel plate adjacent to the boundary as a specific region in the workpiece, and not holding a second region that is farther from the boundary than the first region and includes at least one of the first steel plate and the second steel plate adjacent to the first region.