When it is necessary to punch three or more holes in a tubular or other shaped piece where this form of die can be used, a triple die effects a great saving, as the holes can be punched at one stroke of the press.
Fig. 364 shows a die used for punching three holes in a tube and is intended for use in any simple power press. The dies AAA are placed in a hollow stud which fits in the inside of the piece to be punched. The vertical punch is held in the punch holder as shown. The horizontal punches are operated by means of the inclined arms CC, working in the horizontal slides BB.
The horizontal punches in the illustration are made from drill rod of the desired size; but they may be of any desired form, the opening in the die being made to match. Where work is done in batches sufficiently large to warrant the expense of a triple die, its construction is to be recommended, as better results can be obtained than if one hole is punched at a time.
Fig. 363. Compound Die for Producing Washer at One Operation.