Progressive Die

• A progressive or follow on die has a series of operations. At each station, an operation is performed on a work piece during a stroke of the press.
• Between strokes the piece in the metal strip is transferred to the next station.
• A finished work piece is made at each stroke of the press.
• While the piercing punch cuts a hole in the stroke, the blanking punch blanks out a portion of the metal in which a hole had been pierced at a previous station.
• Thus after the first stroke, when only a hole will be punched, each stroke of the press produces a finished washer.

Construction

• Progressive dies are made with two or more stations arranged in a sequence.
• Each station performs an operation on the workpiece, or provides an idler station, so that the workpiece is completed when the last operation has been accomplished.
• Thereafter each stroke of the ram produces a finished part. Thus after the fourth stroke of a four – station die, each successive stroke will produce a finished part.
• Operations which may be carried out in a progressive die are piercing, blanking, forming, drawing, cut – off, etc.
• The list of possible operations is long. The number and types of operations which may be performed in a progressive die depends upon the ingenuity of the designer.

Working

1. The die block is made up of four pieces and fastened to the die shoe.

2. This permits easy replacement of broken or worn die blocks.

3. The stock is fed from the right and registers against a finger stop (not shown).

4. The first stroke of the press produces a square hole and two notches.

5. These notches form the left end of the first piece.

6. During the upstroke of ram, the stock is moved to the next station against a finger stop (not shown). The stock is positioned for the second stroke.

7. The second station is an idler.

8. The right end of the first piece, the left end of the second piece, and a second square hole are pierced.

9. The ram retracts and the scrap strip is moved to the third station against an automatic stop.

10. This stop picks up the notched V and positions the scrap strip.

11. The third stroke of the ram pierces the four holes as shown in Fig.

12. The fourth stroke, cuts off and forms the radii at the ends of the finished piece.

13. Thereafter every stroke produces a finished part.

Applications

• Progressive dies are used where higher production rates are desired and the material is neither too thick nor too thin. Their use helps in cutting down the material handling costs.

Combination die

A die in which a cutting operation is combined with a noncutting operation is referred to as a combination die. The cutting operations may include blanking, piercing, trimming, and cutoff and are combined with noncutting operations which may include bending, extruding, embossing, and forming.

In a combination die, cutting action is combined with non-cutting actions, i.e. forming. Non-cutting actions may be bending, drawing, extrusion or embossing.

More than one operation is possible in one stroke at a single stage, but the die is more useful for two operations only

Working

1. The die ring is mounted on the die shoe.

2. The die ring is counter bored at the bottom to allow the flange of a pad to travel up and down.

3. This pad is held flush with the face of die by a spring.

4. The drawing punch of required shape is attached to the die shoe.

5. The blanking punch is placed in the punch holder.

6. The stripper (spring operated) strips the skeleton from the blanking punch.

7. As the workpiece comes in contact with the knock out bar during the return stroke, knock out removes the part attached to the punch.

8. As the part is blanked, the blank holding comes down.

9. Then the drawing punch contacts and forces the blank into the drawing die which is made into the blanking punch.