Page 29 - MetalForming November 2012
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press bolster. To accommodate differ- ent size die shoes, bore additional pairs of locator holes. Bumper pins fit into these holes and accurately locate the subplate’s standard notches.
This method is particularly suitable for smaller dies set with a fork truck, as well as heavy dies set with a die cart. Stampers also use bumper pins for accurately setting dies on a moving bolster using a crane—there is no dan- ger of a pin binding as is the case with large centerline locators.
Large Centerline Locators
Large, typically 3-in. or larger loca- tors find use for moving-bolster appli- cations to accurately locate the lower die shoe or subplate. Many new press- es with moving bolsters are fitted with these locators.
Good practice: Bolt the pins to the bolster and carefully lower the die over the pins for setting. Fig. 3 shows a plan view (looking downward) of the bol- ster, pins and lower die. Accurate loca- tion requires that the pins have only a small clearance in the lower die, typi- cally 1⁄16 in. (Fig. 4).
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Fig. 4—Centerline locating pins must fit snugly.
Accurate location is essential when using automatic die clamps. Transfer- press fingers as well as tandem pick- and-place automation require exact location to function without trial-and- error adjustment with every die set. You need sufficient clearance to avoid binding when lifting the die from the bolster, but not so much as to cause inaccurate location. MF
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