Before designing "strip," be sure to understand the tolerance requirements of the parts, material performance, punch tonnage, punch table, SPM (punch per minute), feeding direction, feeding height, mold thickness requirements, material utilization rate, mold life. When designing a strip, CAE analysis should be performed at the same time, mainly considering the thinning rate of the material, which is generally below 25%. Special deep-drawing stainless steel material can be annealed after pre-stretching. Using a high-frequency annealing machine, the thinning rate can be accepted to 40%. When designing the strip, you must communicate with the customer. It is best to ask the customer to provide the previous. To refer to the mold photos or structural drawings, to stretch is also very important. If the length of the mold allows, it is beneficial to change the length of the mold after mold testing. The strip design is an analysis of the molding process of the product, which determines whether the mold is successful. In the design of progressive die, the lifting design is essential. If the lifting rod cannot lift the entire material belt, automatic continuous production cannot be carried out.
In the mold design, mold material selection and heat treatment and surface treatment (such as TD, TICN, TD time takes 3-4 days), especially for tensile parts, if there is no TD, the mold surface will easily pull and burn. For surfaces with small hole positions or tolerances, make adjustable inserts as much as possible to facilitate adjustment during trial and production, to easily achieve the size requirements of parts. Adjustable spare plate should be made at the same time.
When designing a hydrogen spring, design it according to the pressure analyzed by CAE. Do not design an oversized hydrogen spring to prevent the product from rupturing. The usual situation is low pressure, product wrinkling, high pressure, product rupture. To solve the wrinkle of the product, the method of locally increasing the draw bead can be used. The draw bead is first used to fix the sheet and then stretched to reduce wrinkles.
Suggestions for the first trial
During the first mold test, the top plate must be closed slowly. For the stretching process, the thickness of the material level must be tested with a fuse. When the gap between the material levels reaches the thickness of the material, try the mold again. The knife-edge must be aligned first. Please use movable inserts for the draw beads to adjust the height of the draw beads. When testing the mold, the reference hole and reference surface must be equipped with the mold before placing the product on the inspection tool for measurement.
Customer sample requirements
At the laser grade, the red lead powder (the name of the powder used to repair the mold) should be matched, and the feeding materials should be adjusted to solve the problems of cracking, wrinkling, and dimensional tolerances. Correct the main problem when opening the shear, and then make local mold improvements. For 3D complex products, you can use the 3D laser method. Before the 3D laser, you must make 3D graphics, use the CNC to set the reference point, and then send the 3D laser. The 3D laser also needs to be positioned. For the high-strength steel plate, the hard material of the blade should be A88 or V4. In the trial mold, to test the tensile effect, you can put sandpaper on different positions on the material to test the effect.
The above is a summary of some experience in the actual stamping work, I hope to help those who read this article, improve the quasi-term pass rate of the mold, and reduce the number of mold testing.
How to repair the mold with red lead powder?
Mix red lead powder to a thin paste with motor oil. When using, apply red lead powder to the surface where the male mold and the female mold are in contact with your fingers or a brush. Then close the male mold and the female mold, take it out and look at the point where the two touched. Repair the degree and scrape the contact points until the contact surface becomes larger and larger, it is best to ask enough to make the entire surface contactable.