When it comes to metal food cans, the ability to lock-in and preserve the freshness of ingredients, 同时也将有害元素如微生物和氧气拒之门外,这是一个很大的优势.
A closeup of a steel food can.

The double seam, found today on virtually all food and beverage cans, is a simple and proven way to provide such a hermetic seal. 然而, while the end goal is simple, the process can still appear very complex, 特别是品牌谁是新的行业或与金属食品包装工作.

双缝的形成是由两个连续的操作造成的,这两个操作与连接一端的目的有依赖关系, 或盖, to a can body in such a way as to produce the hermetic seal. 一旦罐头末端被放置在罐头上(称为上妆点), 第一个操作缝通过逐渐卷曲末端的外部卷曲边缘开始缝制过程, under the can flange, whilst also curling the can flange downwards at the same time. 第二次操作通过完全压实接缝和所有包含的金属层一起创建密封密封来完成此过程. The ends are supplied with a thin layer of gasket material, 哪一种能填满煤层中产生的空隙,使其真正做到气密.

A diagram of a common double seam.

Getting the Best Results

The world of double seaming may seem complicated, 但有几个关键的技巧会让你更好地了解如何获得无故障的密封.

Tip #1: Understand the terminology of double seaming

双缝通过将罐盖(盖子或瓶口)和罐身的边缘(法兰)联锁而形成密封. 身体钩, which is also commonly known as the can hook, 罐身向下卷曲的法兰是否形成双缝. 盖钩, also called the end hook, 端面成型后向内卷的盖板的卷边是卷曲的吗.

一旦熟悉了基本术语,就可以探索这两种操作的内部工作原理. The initial step in the formation of a double seam, 当缝辊的c形轮廓被驱动到盖钩中,导致其部分卷起来并在罐体的法兰下时发生. 合适的夹头与夹辊配合使用, which acts as both a clamp to hold the cover in place during seaming, 作为一个铁砧来支撑盖子,当接缝卷推动它形成金属. 第二道工序是形成双缝的最后一步. During this process, 该缝进一步压缩并压平罐身侧面, resulting in a gas-tight seal. 第二项操作的结果在第一项操作中确定. 不可能通过调整第二次操作来纠正第一次操作中的错误. 

Tip #2: Recognize the importance of the first operation seam 

第一道工序缝的重要性经常被忽视,因为在大多数自动缝机中很难进入, 通常需要拆卸零件以停止进行第二次手术. If, 然而, the first operation is not properly executed, it will be almost impossible to achieve a successful double seam. 需要考虑的一个事实是,第一操作缝控制着盖钩的正确形成, 因此,是什么控制了身体钩的形成以及台面的深度. 一个有用的提示是严格遵循罐制造商的标准来确定合适的法兰和端厚公差, 可以直径, countersink and tooling profiles.

Tip #3: Check the first operation

If you are experiencing trouble with the first operation, 你需要根据下面的指导方针仔细检查接缝. (Note: As a precaution, 在检查第一次操作前,请确保第二次操作缝已退开或换到脱缝位置). 检查第一次操作缝的适当时间是在缝机的初始设置期间, while installing new seaming rolls and during the re-adjustment.

Tip #4: Evaluate the second operation seam.

After installing or correcting the first operation seaming rolls, 哪个决定了罐子和盖子之间的正确形状, you can move on to optimizing the second operation of the seam.