Three-piece can

Tinplate, also known as tin-plated iron, is the common name for electro-tin-plated thin steel plates. Most of the three-piece cans we mentioned are made of tinplate. Commonly used in canned containers for food, beverages, dry powders, chemical products, and spray products. The process mainly involves the can body (cutting - feeding - bending into a circle - overlapping positioning - resistance welding - touch-up coating - drying - rummaging - beading), can lid (oiling - cutting and blanking - lid punching) - round edge - glue injection - drying and curing) manufacturing, can body and bottom cover crimping and empty can quality inspection. The longitudinal seams of the can body are processed using high-frequency resistance welding, crimping and bonding methods.

The three-piece can has been in use for nearly 200 years. Although it has been improved many times, it is still made of three metal sheets (mostly tinplate): the can body, the bottom and the lid, hence the name "three-piece can

The bottom and lid of ordinary three-piece cans have exactly the same shape, size and manufacturing method, and are collectively called the lid.

There are two main types of sealing forms for the longitudinal seams of the can body: soldering and fusion welding.

Initially, the domestic three-piece cans were all soldered cans (that is, the three-piece cans were made by soldering the overlapping iron sheets at the joints of the can body). However, due to the lead contained in solder, it has become obsolete. With the continuous advancement of science and technology, this tin welding can process is gradually being replaced by the current resistance welding process due to its backward technology, high labor intensity, and unclean construction environment. Image processing substitute.

Fusion welding can avoid lead contamination and consumes less energy and materials, but the production equipment is complex. Domestic and foreign scientists have developed newer side seam overlapping technologies based on the resistance welding process, mainly including: laser welding of cans (that is, the overlap between the side seams of the cans and the overlap between the iron sheets uses laser to weld the can body) and adhesive welding. Can splicing (that is, the overlap of the iron sheets at the seams of the can body is bonded with adhesive).

Three-piece cans have the characteristics of good rigidity, the ability to produce cans of various shapes, high material utilization, easy size change, mature production technology, and a wide variety of packaging products.

Two-piece can

The two-piece can was introduced in the mid-20th century. The entire packaging can is composed of two parts, namely the can body and the can lid (no lower can lid), so it is called a two-piece can. The principle of the process is to pass a metal sheet through a stretch forming die with a punch, causing it to be stretched and deformed so that the bottom and body of the tank are integrated into one body. Together with the lid, it becomes a metal can made of two pieces of metal.

Two-piece cans can be subdivided into several types according to different classification methods. For example, according to the height of the can body, it can be divided into shallow flush cans and deep flush cans; according to the can making material, it can be divided into aluminum cans and iron cans; According to the manufacturing technology, it can be divided into thinning and drawing cans and deep drawing and drawing cans.

Compared with three-piece cans, two-piece cans have the following advantages:

1. Good sealing. The can body is directly formed by the stamping process and does not leak, eliminating the need for leak detection.

2. Ensure product quality. The two-piece can is sealed without welding to avoid lead contamination of the solder can, and it is resistant to high-temperature sterilization to ensure product hygiene.

3. Beautiful and elegant. The can body has no seams and beautiful appearance, and the can body can be continuously decorated and printed with good effect.

4. High production efficiency. The two-piece can has only two parts, and the can body manufacturing process is simple, which is of great benefit to simplifying the process and improving production capacity.

5. Save raw materials. The body of the two-piece can is stretched and deformed during molding, and the wall thickness is thinner than that of the three-piece can. In addition, the body of the two-piece can is integrally formed, without longitudinal seams on the body or joints with the bottom of the can, which also saves material. .

However, two-piece cans have higher requirements on material performance, can-making technology, can-making equipment, etc., and have fewer types of filling materials.

Special-shaped cans

Finally, let me share with you a special kind of metal can: the special-shaped can. As the name suggests, they refer to metal cans with special shapes that are different from ordinary forms. Most of them are innovative and more attractive in appearance. However, special-shaped cans have higher and more complex production process requirements and higher costs.

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