1. The reason for the instability and wrinkling of the flange of the stretched part: the blank holder force is too small, or the relative thickness of the blank is small, or the tensile coefficient is too small.
Solution: Increase the blank holder force or increase the number of stretches.
2. Reasons for surface strain of stamping and drawing parts: low heat treatment hardness, poor finish, improper material selection, excessive material thickness, wear of concave die fillet, poor surface quality of bending blank, unreasonable selection of process plan, insufficient lubrication, etc.
Solution: For stamping parts that need to be stretched many times, under the premise of ensuring the necessary appearance quality, there are traces that can occur during the stretching process. Choose suitable materials and process solutions, lubricate and reduce friction.
3. Reasons for the inconsistent shape and size of stamping and drawing parts: due to inaccurate positioning, in addition to taking measures to reduce springback, the reliability of blank positioning should also be improved.
Solution: The shape of stamping and drawing should be as simple and symmetrical as possible, and one-time stretching should be done as much as possible.
4. The reason for the cracking of the hole after the stretching of the tensile member with the hole: the hole diameter is too large, so that the material around the hole is subjected to a large tensile stress, which leads to fracture.
Solution: Change the sequence of forming process, stretch and form first, and then punch holes at the bottom.
5. The reason for the instability and wrinkling of the upper edge of the cylindrical drawing part: the radius of the concave die fillet is too large, which causes the gap between the concave die and the punch die to be too large, or the blank holder force is too small.
Solution: increase the blank holder force and reduce the radius of the die fillet.
In the drawing process, the cylindrical drawing part is a common metal drawing part, which is widely used. Some customers have special requirements for stretched parts, such as flanging, etc., which can meet the special requirements of the product. Drawing parts processing plants need to fully understand the knowledge of drawing parts flanging processing.
Cylindrical stretching parts with flanging include narrow flanging, cylindrical stretching parts and wide flanging cylindrical stretching parts; narrow flanging cylindrical punching and stretching parts are stretching parts with a small total flange width . When this type of parts is stretched many times, due to the narrow flanging, it can be stretched by punching the flanging cylinder first, and then the flanging process is performed to form the specified narrow flanging shape.
In order to make the flanging better, the conical concave die and the conical pressing ring can be selected for stretching in the last two processes of drawing, and the conical flanging can be vacated, so that the flanging area can be reduced when the part is formed. Radial tensile deformation is beneficial to avoid edge cracking.
When the wide-flanged cylindrical stretched piece needs to be stretched multiple times, for the first stretch, make sure that the flanging specification is equivalent to the flanging specification of the stretched piece. In the next stretching, the flanging specification No change, only the raw material in a certain part of the cylinder migrates to the stretch specification. Because in the subsequent stretching process, even a small deformation caused by a part of the flanging will cause a very large tensile stress in the force transmission area of the cylinder wall, thereby causing the bottom section to crack.Read More →