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How to Solve Folding Defects of Aluminum Forgings?

There are many closed sections on aluminum forgings, the distance between the ribs is short, the ribs are thin, the space between the two ribs and the thickness of the web are large, and many parts of the surface is not processed. Because there are many thin ribs on aluminum forgings, folding problems often occur at the intersection of thin ribs and webs and at the joints of ribs and edges in production. The upper folding of aluminum forged products destroys its continuity, because it weakens the section part, or fatigue cracks occur due to stress concentration in use, which greatly reduces the bearing capacity of forgings. The ribs are generally used to give rigidity or to provide mounting or linking surfaces for other parts. Therefore, folding defects should be prevented.

Ⅰ. The folding defect position of aluminium forged products and reason analysis

1. The folding parts of aluminium forged products can be seen from the structure and shape of the forgings. Folding mostly occurs between the web and rib or between the rib and edge in the production.

2. Causes of folding defects

The unreasonable blank material design leads to differences in metal distribution. The diameter of the long bar is 180 mm × 420 mm in the forging process. Process the long bar to 120 mm × 180 mm × 480 mm according to the quadratic multi-section. Then, draw out the middle part and finally press it into shape on the hydraulic press. The upper and lower ribs are symmetrical, although the shape and appearance of blank material and forgings are close.

Ⅱ. The methods to solve the folding defects of aluminium forged products

①Choose the long bar with the diameter of 170 mm × 280 mm as the blank material. Draw it long in the drawing die, and the diameter of the head end is (170 × 80 + 10) mm. The new improved blank material is selected to be molded, and the upper and lower metals are uniform. In the molding process, the metal deformation is relatively uniform, and the rounded corner of the bar will transit smoothly. In molding, the flow resistance is small in the vertical direction of the die parting, and holes cannot form in the upper part of the rounded corner in the cavity, so that the metal evenly fills the cavity.

②Increase the radius of the convex fillet on the mold and radius of the fillet on the rib and web, so that the metal mold can evenly fill the cavity in molding, the flow resistance is reduced, and the excess metal will flow into the burr groove along the shape of the cavity.

③ There is no folding on the surface of the aluminum forged products after the improved process, and the streamline is distributed along the forgings, which conforms to the drawings and acceptance standards.