PROGRESSIVE TOOL

PROGRESSIVE BLANKING AND PIERCING TOOLS

A simple blanking tool is designed only when the piece part has no internal details. An altogether different tool is to be designed if the piece part is to be produced by the combination of blanking and piercing operations. It can be done in the following way in the same tool. The piercing is performed in the first station. Then the stock strip is advanced to another station where
blanking is carried out. The relative position with the previously pierced hole is
maintained during the blanking operation. The tool is known as "progressive tool" because the processing progresses from station to station.

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Before designing the tool the piece part drawing should be studied carefully. This is to plan the operations to be carried out in different stations. Then the drawing of the stock strip is done. The drawing will be similar to the stock strip as it will appear after it has gone through all the stations till a finished part is removed from it. It must be fully dimensioned and should carry all in formations
necessary to start the design of the tool.

The in formations are:
1.Feed direction
2.The amount of pitch by which the strip should advance after each stroke.
3.Position of stoppers.
4.Width of the strip
5.Scrap bridge dimensions.

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STRIP LAYOUT:-

1. • Fifty to seventy per cent of the cost of stamping is on the material.
2. • The method employed in laying out the strip influences the economic success or failure of any pressing operation.
3. • The strip layouts should be such that the maximum area of the strip is utilized for the production of stamping.
4. • In the tool shown the finished piece part is produced when the strip passes through three stations.
5. • The strip is stopped at the first station by the auxiliary stopper. (Finger Stopper).
6. • During the first stroke of the press ram two holes are pierced by the piercing punch.
7. • The strip is then advanced to the next station.
8. • To do this the first finger stopper is withdrawn and the second finger stopper is engaged.
9. •  Now the pierced hole comes in line with the two pilots.
10. • The pilots are longer than the piercing punches.

     

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PROGRESSIVE TOOLS:-

1. • The strip is then advanced to the next station. To do this the first finger stopper  is withdrawn and the second finger stopper is engaged.
2. • Now the pierced hole comes in line with the two pilots.
3. • The pilots are longer than the piercing punches.
4. • Their nose is conical shaped with a radius at the tip.
5. • During the next stroke of the press ram, the pilots enter into the previously  pierced holes and locate the strip. (Second station)
6. •  In the first station the piercing punches again pierce two holes in the strip.
7. • Again the strip is advanced and brought to stop against the final stop.
8. • During the third stroke of the press ram the pilots enter the pre-pierced holes   and locate the strip.
9. • In the first station the two piercing punches produce two holes.
10. • In the third station the component is blanked and a piece part is obtained.
11. • This piece part will conform to the piece part drawing.
12. • Once the first blank is removed from the strip the strip is lifted to clear the fixed stopper.
13. •The strip is fed till it again stops against the newly formed edge of the opening in the strip created by the removal of the first blank.
14. • Only when a new strip is introduced into the tool the auxiliary stoppers are used again.