| 摘要 |
A draw bead made integral with the die plate or as an insert and having alternating pressure applying surfaces and grooves which will thicken the metals drawn across it minutely at the grooves and will distribute the metal evenly at the pressure surfaces. The draw bead is preferably placed close to the draw radius of the die cavity, and it can have various shapes to compliment the shape of the die cavity. Substantially less blank holder pressure is required because the draw bead restrains the flow of metal and better distributes the metal as it is drawn into the die cavity, and since the draw bead is close to the draw radius, a smaller blank holder is possible. The draw bead can be used to form a portion of the drawn part thereby eliminating a secondary forming operation if the part requires a flat flange about its trim line. When spotting in a new die, metal thickening in certain areas can be greatly reduced or prevented by applying pressure to the underside of the draw bead by hydraulic, pneumatic, or other resilient elements which can be made individually adjustable.
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