The manufacturing principle of plastic bottle caps


Everyone is too familiar with plastic bottle caps, mainly used to seal bottles and cans

Plastic bottle caps are too common and too cheap, so they will be thrown away if they don’t win a prize after opening. Few people understand it. With the increase of environmental protection awareness, many magical uses of bottle caps have appeared on the Internet. Renovation can turn waste into treasure and solve some problems in life.

The metal caps are mainly used for beer, health products, food, etc., and the plastics are mainly used for beverages, food, cosmetics, etc. The material of plastic bottle cap is generally PP material or PE material.

In the early days, the bottle cap was made of cork, and later it was made of screwed iron. In the mid-1990s, the Coca-Cola Company produced plastic bottled beverages, replacing aluminum and iron caps with plastic caps. Plastic caps have been widely used due to their various advantages.

The structure of the bottle cap

The internal measurement of the bottle cap is a section of thread, its function is that during the process of filling the bottle, there will be content remaining in the bottle mouth, in order to facilitate the flushing with water after filling, and also during the opening process In the middle, part of the gas in the bottle is discharged through the gap, so that when the cap is unscrewed, the cap will not fly off and hurt people, and the cap will not fall on the ground and get dirty. There is a small circle under the bottle cap called a one-time breaking anti-theft ring. When the cap is unscrewed, the anti-theft ring will fall off and stay on the bottle. This device is for safety and health. If the anti-theft ring falls off and is not connected to the bottle cap, it means it has been It is no longer safe and hygienic after use. There are many strip-shaped non-slip grooves on the outer edge of the bottle cap, which is convenient to increase the friction when opening the cap.

Plastic bottle caps are manufactured by injection molding process and compression molding process

Compression molding bottle cap production process

Compression-molded bottle caps have no traces of material openings and look more beautiful. The processing temperature is low, the shrinkage is small, and the cap size is more accurate. Put the mixed material into a compression molding machine, heat the material to about 170 degrees Celsius in the machine to become a semi-plasticized state, and squeeze the material into the mold quantitatively. The upper and lower grinding tools are closed and pressed into a bottle cap shape in the grinding tool. The compression molded bottle cap remains in the upper mold. The lower mold is removed. The bottle cap passes through the rotating disc. The bottle cap is removed from the grinding counterclockwise according to the internal thread. Remove the tool. After the bottle cap is compression molded, it is rotated on the machine, and a knife is used to cut a 3 mm edge of the bottle cap into an anti-theft ring connected by multiple points.

Injection molding production process of injection bottle cap

The injection molding mill has a large specific volume and is troublesome to replace. The injection molding requires a large pressure to produce multiple bottle caps, and the material heating temperature is higher, and the energy consumption is higher than that of compression molding. Put the mixed material into the injection molding machine, in the machine, heat the material to about 230 degrees Celsius to become a semi-plasticized state, inject it into the mold cavity of the mold through pressure, and cool and shape it. The bottle cap cooling and shrinking grinding tool rotates counterclockwise, and the bottle cap is pushed out under the action of the push plate to realize the automatic cap falling off. The use of threaded rotation demoulding can ensure the complete forming of the entire thread and effectively avoid the deformation of the bottle cap Scratched. After cutting the anti-theft ring and installing the sealing ring in the bottle cap, a complete bottle cap is produced.

The bottle cap is fastened on the bottle mouth through cooperation with the bottle mouth to prevent the leakage of the contents of the bottle and the invasion of bacteria from the outside. After tightening the bottle cap, the mouth of the bottle goes deep into the top of the bottle cap to the sealing gasket. The inner measuring groove of the bottle mouth and the thread of the bottle cap are in close contact with each other to provide pressure for the sealing surface. Several sealing structures can effectively prevent the substance in the bottle from leaking. Leakage or deterioration.

The manufacturing principle of plastic bottle caps
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