A press is the machine used for performing most of the cold-working operations. Presses are used for mass production of articles economically, quickly and accurately. They find wide application in performing a large variety of operations such as shearing, bending, deep drawing, stamping, coining, forging, etc. Examples of products made by press-working include: drawing and formed parts of automobile and aircraft, electrical appliances, coining money, kitchenware, thick cylindrical shells, notched motor laminations, toys, radio, jewellery, etc.
Presses are available in large variety as discussed, but they have the following main features in common. A press basically consists of the following components.
(i) A rigid machine frame and bed forming the body of press. Bed supports the bolster plate and die and is usually open in the centre to allow the cut blank or scrap to fall down.
(ii) Bolster plate carries the press tools (die and other accessories) and is fixed to the top of bed.
(iii) Ram (slide) carries the punch and moves up and down to carry out die cutting and other forming operations.
(iv) Power source and mechanism to move the ram in a typical fashion.
(v) A knockout system comprising a mechanism that usually operates on the upstroke of ram (or punch) and helps in the detaching of the cut blank (or formed part) from the punch (for example, a stripper plate)
(vi) Die-assembly comprising (a) female member or a die mounted and bolted to the bolster plate, and (b) male member or punch mounted with the ram, reciprocating up and down.
(vii) Press accessories and auxiliary equipment consisting of devices that help in conducting the press operations effectively, for example, roller-feed device for pulling the strip off a stock reel through the press or die cushion platen often used in drawing operations and actuated by spring or compressed air to give cushioning effect on the die.
Roller-feed device for pulling sheet metal stock or strip off the stock reel and through the die and finally wrapping the scrap on the scrap reel.
Details of a typical drawing die. The blank is first placed and located above the die. The blank holder plate then comes down and holds the blank at its edges. Later, the punch descends and forces the blank completely through the die producing an article of desired shape (or as per the configuration of the die). A die cushion platen is often used in drawing operations and is actuated by spring or compressed air to give cushioning effect on the die.
See More: Wire Drawing
See More: Tube Drawing
See More: Sheet MetalForming:(Press Working)
