The processing difficulty of fine-blanking parts directly affects its manufacturing cost. Therefore, studying the processing difficulty of fine-blanking parts and taking effective technical measures for difficult-to-machine parts will help reduce costs and increase efficiency. For a specific fine blanking part, the manufacturing cost is directly related to its processing difficulty level. The greater the processing difficulty, the higher the manufacturing cost.
1. Dimensional factors: sheet thickness, shape size;
2. Shearing surface elements: shearing surface tearing and intact rate requirements, collapse angle size;
3. Material elements: hardness, strength, carbide spheroidization rate (medium and high carbon steel or alloy steel), anisotropy, etc.;
4. Structural elements: acute angle and radius of fillet, slot width, cantilever, hole diameter, hole spacing, ratio of hole margin to material thickness, whether there is tooth shape, whether there is half punching, countersinking, local thinning, Composite forming of internal and external chamfering, bending, stretching, flanging, etc.;
5. Accuracy factors: shape and position accuracy;
6. Other elements: heat treatment, surface treatment and other requirements.
The greater the thickness and outer dimensions, the greater the difficulty of fine blanking. The thickness of the sheet suitable for fine blanking is generally between 3 and 12 mm, and the fine blanking difficulty index increases linearly with the thickness. The greater the thickness, the more prone to tearing and peeling defects on the shear surface, and the lower the die life. Generally speaking, if the thickness is less than 5mm, it is easy to fine blank; if the thickness is 5-9mm, it is moderately difficult; if the thickness is greater than 9mm, it is difficult.
The size of the fine-blanking parts, in theory, as long as the tonnage of the equipment is large enough, there is no limit. However, when the external size is large to a certain extent, due to the anisotropy of the material and the force and deformation of the die during the punching process, it is difficult to ensure the dimensional accuracy of the fine blanking parts. Generally, the maximum external dimension is less than 100mm, which is easy to fine blanking; 100-250mm, it is medium difficulty; greater than 250mm, it is difficult.
Therefore, in actual production, for thick and large fine blanking parts, the following measures should be taken:
1. The rigidity of the mold should be large enough, and the main measure to increase the rigidity of the mold is to increase the thickness of the die, the ring gear platen and the template as much as possible;
2. A stress ring is set on the outer periphery of the die to reduce its stress deformation and prevent cracking;
3. According to the difference between the size of the stamping part and the size of the mold, make appropriate compensation for the size of the mold edge.