Miscellaneous Dies

Chapter 5 Miscellaneous Dies

Contents • Basic Construction and working of – Shaving dies – Trimming dies – Progressive dies – Compound dies – Combination dies

COINING DIES

• • • •

Simple Follow or progressive Combination Compound

• SIMPLE DIE: – In a simple die, only one operation is performed at each stroke of the ram. All the press operations explained later are carried out in simple die.

• A progressive die performs two or more operations on a sheet-metal coil at two or more stations with each press stroke. The part is fabricated progressively. The coil is fed from one station to the next and different operations (e.g., punching, notching, bending, and blanking) are performed at each station.

• The progressive die is a multiple-station die, used for parts have depth to diameter ratio is too large. It performs number of operations at two or more stations, during each stroke of the press. • The product is completed in several successive draws. This die can perform very complex work, includes piercing, blanking, forming and like operations. A two stage progressive blanking and piercing die is shown in fig.

• In a compound die two or more cutting operations are accomplished at one station of the press in every stroke of the ram. As can be seen it, allows blanking and punching operation simultaneously. It has a more complicated construction than single drop-through die

• Advantages – close dimensional tolerances, – greatest accuracy of parts, – as all work is done in a single stroke.

Limitations: – (i) The compound dies are limited to relatively simple processes such as blanking and piercing. – (ii) It can perform only cutting operations not shaping or bending operations.

• In a combination die, both cutting and non-cutting operations are accomplished at one station of the press in every stroke of the ram. The combination die is used to perform both cutting (i.e., blanking) and shaping (i. e. bending, drawing) operations. In a blanking-drawing combination die, first, the blanking punch is operated which produces a blank from the metal strip as an output product. Secondly, a drawing punch is actuated and draws the blank, into the required shape. This time, blanking punch act as a blank holder.