The main method is to use the pressing device on the die structure to press the edge ring, so that the part of the blank that may wrinkle is sandwiched between the die plane and the edge ring, so that the blank can smoothly pass between the two planes. Using blank holder or sill can also effectively increase the radial tensile stress and reduce the tangential compressive stress, which is also an effective measure to prevent wrinkling.
With the continuous downward movement of the punch, the outer diameter of the blank left on the end face of the female die decreases, and the circular blank is gradually pulled into the gap between the male die and the female die to form a straight wall, while the material below the male die becomes the bottom of the drawing part. When all the sheets enter the gap between the punch and the die, the drawing process ends, and the plane blank becomes a cup-shaped part with a certain diameter and height.
Compared with the blanking die, the working parts of the drawing punch and die should not have sharp cutting edges, but should have certain rounded corners, and the unilateral gap between the punch and die is slightly larger than the material thickness.
Extended data:
After drawing, the wall thickness and hardness of simple parts will change. The thickness of the upper part of the side wall of the circular single piece increases the most, which can reach 20% ~ 30%. However, where the corner between the simple wall and the bottom is slightly higher, the minimum thickness reduction of the plate can reach 8%~ 10% at most. When the stress in this section exceeds the strength limit of the material at this time, the workpiece is cracked here.
The formation mechanism of stretch marks and tensile cracks is the same, but the difference is only in different degrees. When the ingot is pulled from the crystallization tank to the casting shaft after the crystallization of the melt, the strength of the metal shell formed by the melt just crystallized in the crystallization tank is low.
If it is not enough to resist the friction between the ingot and the working surface of the crystallization tank, the surface of the ingot will be pulled out of stripes. In severe cases, the surface of the ingot will be pulled out of the crack laterally, and in severe cases, the local hard shell may be pulled out, resulting in depression at the crack.
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Baidu Encyclopedia-Drawing Technology
If the problem with hands is that the joints are thick, it is difficult to thin hands, but if the hands are fleshy, you can try the following methods.