Seaming

双缝, 现在几乎所有的食品和饮料罐上都有, 是否有一种简单且经过验证的方法来提供这种密封. However, 虽然最终目标很简单, 这个过程看起来仍然非常复杂, particularly to brands who are new to the industry or to working with metal food packaging.

The formation of a double seam results from two sequential operations that have a dependent relationship with the aim of joining an end, or lid, 密封:以这种方式使罐体产生密封. Once the can end has been placed onto the can (called the make-up point), the first operation seam begins the seaming process by gradually curling the outside curled edge of the end, 罐缘下, 同时也卷罐法兰在同一时间向下. The second operation finishes this process off by fully compacting the seam and all the included layers of metal together to create the hermetic seal. 两端提供了一层薄薄的垫圈材料, which fills any voids created within the seam to make it truly gas-tight.

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获得最好的结果

双缝的世界可能看起来很复杂, but a few key tips will lend you a better sense of how to achieve a fault-free seal.

技巧1:了解双缝的术语

A double seam creates a hermetic seal by interlocking the edges (flanges) both of the cover (lid or end) and body of the can. The body hook, 也就是俗称的罐头勾, is the flange of the can body that is curled downward in the formation of the double seam. The cover hook, 也叫尾钩, is the curled edge of the cover that is curled inward after the end is formed.

Once you are familiar with the basic terms, you can explore the inner workings of the two operations. 双煤层形成的初始阶段, occurs when the c-shaped profile of the seam roll is driven into the cover hook causing it to be partially rolled up and under the flange of the can body. A suitable seaming chuck is used in conjunction with the seaming rolls, 在缝合过程中，哪一个既可以作为夹子将盖子固定在适当的位置, and as an anvil to support the cover as the seaming roll pushes against it to form the metal. The second operation is the final step in the formation of a double seam. 在这个过程中, the seam is further compressed and flattened against the side of the can body, 造成气密密封. The results of the second operation are determined in the first operation. It is not possible to correct errors in the first operation by adjusting the second operation. 

提示2:认识到第一个操作缝的重要性 

The importance of the first operation seam is frequently overlooked as it is difficult to access in most automated seamers, often requiring parts to be removed to stop the second operation being carried out. If, however, 第一个操作执行错误, 想要成功地实现双缝几乎是不可能的. A fact to consider is that the first operation seam controls proper formation of the cover hook, which consequently controls the formation of the body hook as well as the depth of the countersink. A helpful tip is to closely follow the can manufacturer’s standards for determining suitable tolerances for flange and end thicknesses, can diameter, 台面和模具轮廓.

提示#3:检查第一个操作

如果你在第一次手术中遇到麻烦, you’ll need to carefully examine the seam according to the following guidelines. (注:作为预防措施, be sure that the second operation seam is backed off or changed to the off-seam position prior to inspecting the first operation). Appropriate times to check the first operation seam are during the initial set-up of a seamer, 在安装新的缝辊和重新调整时.

技巧4:计算第二个操作缝.

安装或纠偏后第一次操作缝辊, which will determine the correct formation between the can and the cover, 您可以继续优化接缝的第二个操作.