| 摘要 |
PURPOSE:To obtain inexpensively a uniform product in short forming time by forming a recess to the outside circumferential part of a cylindrical blank pipe, inserting a space member into said recess and forming the pipe to a spherical shape by pressing. CONSTITUTION:A blank pipe 10 formed by cutting a pipe material is inserted into a die press 16. The press 16 has a projecting part 11' forming a recess to the pipe 10. The lower die thereof is divided to a lower left die 13 and a lower right die 14 which are movable forward and backward in a horizontal direction and have receiving recessed 15 for forming the recess 12. The pipe 10 is pressed by an upper die 11 and the dies 13, 14, by which the recess 12 is formed. A space member 17 is inserted into the recess 12 and the pipe 10 is inserted into a die press 22 formed with semi-spherical recesses 20, 21 to an upper die 18 and a lower die 19 so as to face each other in such a way that the axis of the pipe 10 is positioned in a vertical direction. The pipe 10 is then formed to a spherical shape by the pressing force of both dies 18, 19 and the member 17 is removed. The hollow ball having the recess 12 on the outside circumferential surface is thus obtd. |
