Stamping parts common bad and countermeasures
Let's take a look at the various defects of stamping parts produced by stamping factories, as well as the causes and preventive measures.
We covered three points briefly in the last article. Let's look at a few others.
4. The precision of the outer edge and the inner hole of the punching parts is reduced and the size changes
1) Reasons
Positioning pin, stop pin and other positions change or wear too much;
The operator's negligence when feeding the left and right deviation;
The dimensional accuracy of the strip is low, too narrow and too wide feeding difficulties make it difficult to send to the designated place, the strip will be in the guide plate before and after deviation, out of the workpiece hole and shape before and after the position deviation.
5. When the parts are bent, the size and shape are not qualified
1) Reasons
The rebound of materials causes the product to be unqualified;
The positioner is worn and deformed, and the positioning of the strip is not correct, so a new positioner must be replaced.
In the unguided bending die, when adjusting on the press, improper adjustment of the lower dead point of the press slider will also cause the shape and size of the bending parts to be unqualified;
The pressing device of the die fails or does not play the pressing role at all. The pressing force must be readjusted or the pressure spring must be replaced to make it work normally.
2) Measures to reduce rebound
The stamping materials with large elastic modulus and small yield point are selected.
Add correction procedure, using correction bending instead of free bending;
Before bending, the material should be annealed, so that the cold hardening material is softened before bending and forming;
If the shape deformation occurs in the stamping process, it is difficult to eliminate; Should be replaced or trimmed punch and die slope, and make the gap equal to the minimum thickness of the material;
Increase the contact area between the die and the workpiece, reduce the contact area between the punch and the workpiece;
6. Cracks occur at the bending parts of the bending parts
1) Countermeasures
Eliminate the burr on the outside of the bending area, which will cause the stress concentration in the area and reduce the bending deformation; Remove burrs from this area;
The burr side is placed inside the curved area;
When bending the workpiece, it is best to make the bending direction and the fiber direction of the material (rolling direction) perpendicular;
The bending radius should not be too small, and the fillet radius should be increased as far as possible under the condition of mass.
The surface of the bending billet should be smooth and clean, without obvious bumps and scars;
When bending, the intermediate annealing process is used to eliminate the internal stress. After softening, the bending rarely produces cracks.
When bending large bending parts must be coated with lubricant to reduce the friction in the bending process.
7. Deviation of the bending parts in the bending process
1) Reasons
In the bending process, when the billet slides along the surface of the die, it will be subjected to friction resistance. If the friction resistance difference between the two sides of the billet is large, the billet will shift to the side with greater friction resistance.
2) Countermeasures
The bending parts with asymmetrical shapes are formed by symmetrical bending (single-side bending parts are formed by symmetrical bending of two pieces before cutting).
The elastic press device is added on the bending die so that the billet can be pressed to prevent movement during bending.
Using the inner hole and shape positioning form to make its positioning accurate.
8. The surface of the bending part is bruised
1) Reasons and countermeasures
For copper, aluminum alloy and other soft materials for continuous operation bending, metal particles or dregs are easy to attach to the surface of the working part, so that the parts appear large scratches, and produce scratches;
When the bending direction is parallel to the rolling direction of the material, cracks will occur on the surface of the workpiece, which will reduce the surface quality of the workpiece. In more than two parts of the bending, should be as far as possible to ensure that the bending direction and rolling direction have a certain Angle;
Die fillet radius is too small, the bending part of the impact marks. Polishing the die and enlarging the radius of the die fillet can avoid the abrasion of bending parts;
Die gap should not be too small, too small gap will cause thinning abrasion. In the stamping process to always check the change of the gap of the die;
The depth of punch into the concave die is too large will produce parts surface scratches, so in order to ensure that the impact of rebound, should be appropriate to reduce the depth of punch into the concave die;
