Stamping is one of the practical processes for the production of large quantities of parts. In the stamping production process, the mold has the most problems, and it is the most important factor in the entire stamping production factor. Directly affect production efficiency and cost. Affect the delivery cycle of the product. Mold problems are mainly concentrated in mold damage, product quality defects and mold sharpening, which have long plagued industry production. Only these key points are handled correctly. Stamping production can be carried out smoothly.

1 mold failure
Mold failure is the most prone problem in stamping production, often resulting in production downtime, affecting product production cycle. Therefore, the cause of the mold failure must be found as soon as possible, and reasonable maintenance.

 █ mold damage

Mold damage refers to the cracking, breaking, and opening of the mold. To deal with the problem of mold damage, it is necessary to find the reason from the design of the mold, the manufacturing process and the use of the mold.

 █ card model

During the stamping process, once the mold clamping is not flexible or even stuck, it is necessary to stop production immediately, find out the cause of the card and eliminate the fault. Otherwise, the fault will be enlarged and the mold will be damaged.

The main causes of the card mold are: poor mold orientation and tilt. Or there is a foreign object between the templates, so that the template can not be flat; the mold strength design is not enough or the force is uneven. The deformation of the mold is caused. For example, the hardness and thickness of the mold base and the template are too small, and it is easily deformed by external force; the position of the mold is not installed correctly, and the positioning error of the upper and lower molds is excessive. Or the accuracy of the press is too poor, causing the mold to interfere; the strength of the punch is not enough, the size of the punch is too close, and the lateral force of the mold is unbalanced. At this time, the punch strength should be increased to enhance the guiding protection of the discharge plate.

 █ mold damage and repair

The cost of stamping production is high. Usually the mold cost is 1/5-1/4 of the total cost of the part. This is because, in addition to the difficulty in manufacturing the mold and the high cost. The cost of mold repair and sharpening maintenance after putting into production is also high, and the original cost of the mold only accounts for about 40% of the total mold cost. Therefore, timely repair of the mold to prevent mold damage can greatly reduce the cost of stamping production.

After the mold is damaged, there is a question of maintenance and scrapping. Generally speaking. Unnatural wear of stamping dies, such as damage to non-critical parts. And the small punch is broken, the punch is thick and short, the concave template is cracked, and the cutting edge is cracked. Most of them can be restored to normal condition by repairing and re-commissioned into stamping production. but. When the key parts of the mold are seriously damaged, sometimes the convex and concave molds are damaged at the same time. The one-time repair cost exceeds 70% of the original cost of the die, or the mold life is near. The meaning of maintenance is not great. At this time, the scrap mold should be considered: except for the large mold and the continuous mold with complicated structure. When the mold repair technology is too complicated and the cost of mold repair is too large, the difficulty will inevitably make the maintenance period too long, which will seriously affect the normal production of stamping. It is necessary to choose to scrap the scrap beforehand and remanufacture the mold.

Under normal conditions, the main failure mode of the die is excessive wear. Delivered from the manufacture of new molds. Until the burrs of the punched parts exceed the standard, the size and shape accuracy of the parts are too poor, and the mold can no longer be repaired or no repair value at all, the mold can only be scrapped. From the time the new mold is put into use to the end of the scrap. It usually takes many repairs and sharpening.

2 Parts quality defects

The most common defect in the quality of the part is the size of the product. Only a few products have surface quality problems.

 █ size tolerance

Out-of-size defects are a serious drawback of stamped parts. In this regard, we must first check and check the design of the mold to eliminate the reasons for design and manufacture. If the tolerance is related to the thickness of the material, the thickness, material and hardness of the stamped material should be checked.

In the stamping production process, the size is out of tolerance, mainly due to the wear of the mold, poor positioning and deformation of the workpiece. The edge of the mold is worn. It will cause the burr to be too large or the size of the cut to become larger, the punching becomes smaller, and the flatness is too poor, and the mold should be sharpened or replaced. Poor positioning and guidance includes no guide, guide pin or other positioning device does not work, the feeder does not relax, the positioning block wears too long, the feed distance is too long, the length of the guide plate is wrong or the guide gap is too large. The parts are deformed during production, mainly including impact deformation. For example, the blowing pressure of the product is too strong or the gravity falls. The impact is too large. When the material is squeezed or deformed during discharge, the discharge position should be cleared or the discharge space should be increased. : Ejection is improperly deformed. For example, the top material pin is improperly formulated, the spring force is not suitable, or the ejection force is too long. The elastic force should be adjusted or the position or the number of pins should be changed; Some of the curved parts can not allow the material to overlap, and must be dropped every time. When the dish strain occurs, the pressure pad can be used to eliminate it; the punching and shearing deformation is mainly caused by the material being distorted. The size is increased or the center is asymmetrical; the deformation of the chip is caused by the floating of the scrap or the fines remaining on the die face or the foreign matter and the like.

 █ Surface quality is unqualified

The surface quality of stamped parts is mainly due to excessive burrs. The reason for the excessive burrs of the workpiece is firstly the wear of the die edge. The mold should be re-ground (described below) to ensure sharp edges. Secondly, the interval between the convex and concave molds is unreasonable. If the gap is too large, most of the sides are polished bands. If the gap is too small, the secondary shear surface will appear. If the hardness of the material is too high, the material should be replaced or the gap should be increased. When the punching edge is too small or the trimming material is too small, the material will be pulled into the gap of the mold to become a flash. At this point, it is necessary to increase the size of the lapped edge or the trimming margin.

3 mold sharpening

Reasonable sharpening of the mold in stamping production. It can effectively improve the life of the die, save the cost of the mold, and greatly reduce the cost of the product.

4 Conclusion

Stamping production efficiency and cost are highly dependent on the mold. For the failure of the mold in the production process, specific problems should be analyzed and the correct maintenance plan should be formulated. Timely resolution of mold damage, jamming, sharpening and product quality defects. To deal with the relationship between mold repair and scrapping, it is possible to reduce the time for mold-off repair, shorten the production cycle, and ensure the normal production of stamping.

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