(1) Restrictions on raw materials for steel drums To make steel drums, the material must have low carbon content and good plasticity. Because of its good processing performance, welding, stamping, and bulging are easy to ensure quality. But the hemming is different, because the size of the hemming roller groove cannot change with the hemming process, and the hemming force must be gradually transferred to the center of the hemming through the peripheral material, so that the center can be rolled. The better the plasticity of the material, the more difficult it is to transmit force. It is conceivable that if the material of the steel drum is spring steel, the same material as the law of a clock, not to mention rolling ten layers, I am afraid it is also easy to roll 20 layers, because it has good elasticity and rigidity, and the sealing force is very high through the outer volume. Easy to reach the center. But this is impossible, because this material has good elasticity, so after the end of the rolling, when the rolling force disappears, it is easy to rebound back to the original state, that is, to return to the beginning of the rolling. This is obviously not what we need. Therefore, it is impossible for us to choose highly elastic materials. In terms of the materials currently used to make steel drums in the world, our country has the most rigid materials, so the quality is more difficult to guarantee. And the number of curling layers does not exceed seven. According to the research of relevant foreign experts, the number of layers of steel drum hemming will not exceed seven, and obviously the sealing force cannot be transmitted that far.
(2) The limitation of the steel drum coil sealing technology. At present, the most advanced coil sealing technology in the world is similar, except for the change of the crimping roll profile and the difference of the coil sealing speed. This process method is the most economical method for mass production, and it is also the method with the lowest quality cost. If you don't care about these, there may be a better way to transmit the sealing force farther, so that the curling can reach more than seven layers. But for steel drums, a good seven-layer crimp is enough. If the current quality of the crimp is not good, you need to find other problems.
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