Hot press molding method, article molded by hot press molding, and mold for hot pressing

Abstract

In a hot press molding method for press-molding a heated material and cooling the material while holding the material in a mold, during press molding of the material, shape changes including a portion that curves with respect to a longitudinal direction of the material are molded at longitudinal opposite end portions of the material and resistance to thermal contraction force of the material in the longitudinal direction during cooling is imparted. In one embodiment of the present invention, the shape changes molded on the material during the press molding are minute protrusions provided on surfaces of the longitudinal opposite end portions of the material. The invention makes it possible to suppress thermal contraction of the material during cooling in hot press molding to thereby prevent defects associated therewith.

1 . A hot press molding method for press-molding a heated material and cooling the material while holding the material in a mold,
 wherein, during press molding of the material, shape changes including a portion that curves with respect to a longitudinal direction of the material are molded at longitudinal opposite end portions of the material and resistance to thermal contraction force of the material in the longitudinal direction during cooling is imparted.   
     
     
         2 . The hot press molding method according to  claim 1 , wherein the shape changes molded on the material during the press molding are a plurality of minute protrusions provided on surfaces of the longitudinal opposite end portions of the material. 
     
     
         3 . The hot press molding method according to  claim 1 , wherein the shape changes molded on the material during the press molding are flanges molded on the longitudinal opposite ends of the material. 
     
     
         4 . A hot press molded article obtained by the hot press molding method according to  claim 1 . 
     
     
         5 . A mold for hot pressing, the mold including an upper mold and a lower mold, for sandwiching a heated material between the upper mold and the lower mold to press-mold the material, and for holding the material in the mold to cool the material,
 wherein a plurality of protruding portions protruding toward the upper mold or a plurality of recessed portions recessed from the upper mold toward the lower mold are provided at a portion of the lower mold corresponding to a longitudinal end portion of the material,   a plurality of recessed portions or a plurality of protruding portions corresponding to the protruding portions or the recessed portions provided to the lower mold are provided to the upper mold, and   a plurality of minute protrusions are molded on a surface of the longitudinal end portion of the material by the protruding portions or the recessed portions provided to the lower mold and the recessed portions or the protruding portions provided to the upper mold during press molding with the upper mold and the lower mold.   
     
     
         6 . A mold for hot pressing, the mold including an upper mold and a lower mold, for sandwiching a heated material between the upper mold and the lower mold to press-mold the material, and for holding the material in the mold to cool the material,
 wherein a flange bending from the upper mold toward the lower mold or from the lower mold toward the upper mold is molded at a longitudinal end of the material by the upper mold and the lower mold during the press molding.   
     
     
         7 . A hot press molded article obtained by the hot press molding method according to  claim 2 . 
     
     
         8 . A hot press molded article obtained by the hot press molding method according to  claim 3 .