Machinery's Handbook, 31st Edition
1456
Steel Rule Dies
Upper die shoe
Lignostone die block
Steel rule with land for shearing
Fool proofing pin locations Parallels for slug clearance
Piercing punch
Male punch
Fool proofing pin locations
Die strippers may be neoprene, spring ejector, or positive knock out
Lower die plate
Lower die shoe
Subdie plate
Fig. 64. Steel Rule Die for Cutting a Circular Shape, Sectioned to Show the Construction Steel rule die blocks can carry punches of various shapes to pierce holes in the stock, also projections designed to form strengthening ribs and other shapes in material such as aluminum, at the same time as the die cuts the component to shape. Several dies can be combined or nested, and operated together in a large press, to produce various shapes simultaneously from one sheet of material. As shown in Fig. 64, the die steel is held in the die block slot on its edge, usually against the flat platen of a die set attached to the moving slide of the press. The sharp, free end of the rule faces toward the workpiece, which is supported by the face of the other die half. This other die half may be flat or may have a punch attached to it, as shown, and it with stands the pressure exerted in the cutting or forming action when the press is operated. The closed height of the die is adjusted to permit the cutting edge to penetrate into the material to the extent needed, or, if there is a punch, to carry the cutting edges just past the punch edges for the cutting operation. After the sharp edge has penetrated it, the material often clings to the sides of the knife. Ejector inserts made from rubber, combinations of cork and rubber, and specially compounded plastics material, or purpose-made ejectors, either spring- or positively actuated, are installed in various positions alongside the steel rules and the punch. These ejectors are compressed as the dies close, and when the dies open, they expand, pushing the material clear of the knives or the punch. The cutting edges of the steel rules can be of several shapes, as shown in profile in Fig. 65, to suit the material to be cut, or the type of cutting operation. Shape A is used for shearing in the punch in making tools for blanking and piercing operations, the sharp edge later being modified to a flat, producing a 90 ° cutting edge, B . The other shapes in Fig. 65 are used for cutting various soft materials that are pressed against a flat surface for cutting. The shape at C is used for thin, and the shape at D for thicker materials. Steel rule die steel is supplied in lengths of 30 and 50 in., or in coils of any length, with the edges ground to the desired shape, and heat treated, ready for use. The rule material width is usually referred to as the height, and material can be obtained in heights of 0.95, 1, 1 1 ∕ 8, 1 1 ∕ 4 , and 1 1 ∕ 2 in. Rules are available in thicknesses of 0.055, 0.083, 0.11, 0.138, 0.166, and 0.25 in. (4 to 18 points in printers’ measure of 72 points = 1 in.). Generally, stock thicknesses of 0.138 or 0.166 in. (10 and 12 points) are preferred, the thinner rules being used mainly for dies requiring intricate outlines. The stock can be obtained in soft or hard temper. The standard edge bevel is 46 ° , but bevels of 40 to 50 ° can be used. Thinner rule stock is easiest to form to shape and is often used for short runs of 50 pieces or thereabouts.
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