This historic book may have numerous typos and missing text. Purchasers can usually download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1919 edition. Excerpt: ... be found necessary to shear the stock somewhat wider than in general practice for plain blanking, and this amount can be determined only by trial. The stripper should be milled with little more than enough room for the stock to pass. This will hold the stock flat and prevent wrinkling, to some extent. ...
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This historic book may have numerous typos and missing text. Purchasers can usually download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1919 edition. Excerpt: ... be found necessary to shear the stock somewhat wider than in general practice for plain blanking, and this amount can be determined only by trial. The stripper should be milled with little more than enough room for the stock to pass. This will hold the stock flat and prevent wrinkling, to some extent. With the feed rolls tight and the dies made right, this wiH be found a very cheap and satisfactory way of making shallow shells. j.1 ii-ij Other Applications Of The Pinch Off Principle This principle of draw and pinch off tools can be applied advantageously to other work. Consider for the moment Fig. 244, which is the powder box for which the cover, Fig. 242, is made. This box is finished nV in. deep and crowned on the bottom the same as the cover. On a double acting cam actuated press, the box is first drawn about 3V in. larger in diameter than finish eize. Then it is redrawn and pinched off to the proper height. A very satisfactory result is-ob tained and no further trimming is necessary if the punch is kept sharp. This type of punch and die can very often be used to advantage in drawing and trimming steel shells for various purposes. In Fig. 245 is shown a cup made of 0.0437 sheet steel, drawn upon a cam actuated cut-and-draw press and then redrawn to the dimensions given. After annealing it had been the practice to turn or face off in a drilling machine, the cup being held in special jaws while the cutting tool was fastened in the spindle. The cup was then put through a final draw and again sent to the drilling machine to be faced off to correct height, as shown at Fig. 246. As may be supposed, there were many rejections due to the facing off of too much material, or to rough edges. In the latter case it was necessary to send the...
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