| 摘要 |
PROBLEM TO BE SOLVED: To increase depth and narrowness and improve the limit of drilling process of a stock material by linearly holding the forming part of an extrusion pin during a forming process. SOLUTION: A guide sleeve 22 linearly holding an extrusion pin 11 for a drilling process is fitted to the outer periphery of the forming part 21 of the extrusion pin 11 from the radial direction as a two-split state, and during the forming, the forming part 21 is kept straight. The guide sleeve 22 is so constituted that it is kept at a position where it covers the forming part 21 as far as the tip of the part by the urging force of a spring 26 before extruding start and it is pushed to the rear flowing part to reach it, and it returns from the retreating position after completion of extrusion. An auxiliary support ring 23 is attached to the rearwardly projected part from the guide sleeve 22.
|
