COMPOUND TOOL

COMPOUND PIERCING AND BLANKING  TOOLS:-

1. • Compound tools also produce blanks having holes.
2. •  In a compound tool both the piercing and blanking operations are performed simultaneously.
3. • The conventional positions of punch and die are inverted.
4. • The blanking punch is clamped to the bottom plate of the tool.
5. • The blanking die is clamped to the top plate.
6. • The piercing punches are positioned in-side the blanking die opening.
7. • They are mounted on punch holders.
8. • Their mating piercing dies are formed in the blanking punch.
9. • Because of the positions the mating parts assume, the blanking and piercing operations take place in the opposite directions, but simultaneously.
10. • Because of this the piercing' and blanking burrs are formed on the same side of the piece part.
11. • A fixed stripper cannot be clamped to the die because the die is mounted on the top plate.
12. •  A moveable stripper is fitted around the blanking punch.
13. • The stripper is actuated by self contained compression springs or by the die cushion of the press.
14. •  In addition to stripper some means should be provided to knockout or shed the piece art from the blanking die as well as to strip itself from the piercing punches.
15. • This is achieved by a shedder which is closely fitted in the blanking die and around the piercing punches.
16. • The shedder can be actuated by a compression spring or can be connected to  the knockout mechanism of the press.
17. • The slug produced from the piercing operation falls down through the opening provided in the bottom plate.
18. • The blanking die walls are straight without angular clearance.
19. • The piece parts are knocked out of the die as soon as the blanking is over.