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Metal packaging materials have good decorative properties on the surface, high strength, convenience for storage and transportation, and are increasingly appreciated by the public. The metal cans were originally used to package foods. The earliest can be traced back to the era of Napoleon before 200 years ago. Three beverage cans have become one of the main forms of packaging for carbonated drinks, juices, and beer. Currently, there are many types of drink cans on the market, and most of the can lids use pull-type easy-open lids. However, the currently used open lids have structural defects.
1 Opening principle and classification of pull-open cover
Pull-type easy to open the lid referred to as pull-open can lid, this type of lid is easy to open, just pull the ring on the open, a little hard pull to open the lid. The opening principle of the pull-open easy-open cover is: first pre-press the indentation at the open position of the can lid to reduce its local strength, and generate a relatively concentrated stress near the pull ring at the time of opening. Under the action of the shear force, it is the indentation area. Crack open and open. Under normal circumstances, the pressure difference between the inside and outside the tank is small, the shear force generated at the indentation is small and uniform, and the cans will not crack on their own, thus ensuring the safety of the canned products during transportation and storage.
Pull-type easy cover has two forms: one is a small mouth type, when the pull ring is pulled up, the tank lid opens a small mouth, so that the small mouth can suck or pour the fluid content, and the other is a large mouth type, the pull ring pulls up Almost the entire can lid was removed to remove solid, powdered or highly viscous self-thickened contents. The article mainly discusses the small opening easy cover, which has a wide range of applications in beverage cans. At present, there are two kinds of easy opening covers: full tear and non-full tear. Both types of cans have advantages and disadvantages.
2 Small mouth type easy to open the characteristics analysis
The application of full tear and easy opening covers a long time and is most widely used in current beverage cans. Its style is shown in Figure 1. The full tearing and easy opening cover manufacturing technology is mature, the structure is beautiful, the stacking performance is good, and the storage and display are reluctant. However, the pull ring that is completely torn and easily opened will be discarded after being opened, causing environmental pollution and possibly injuring others. This is the weakness of full tearing and easy opening. For this weakness of the full tearing and easy opening cover, people designed a non-full tearing easy opening cover that is a retention type easy opening cover, as shown in Figure 2
Retention-type easy-open lids do not come off the lid when the pull-tab is pulled up, but are pushed into the tank. This structure avoids the problem of injury and environmental pollution caused by the throwing of the pull ring and the opening. This structure also has a lot of loopholes. Canned beverages are easily transported, displayed on display, put into refrigerators, and carried by consumers. They are easily exposed to contamination by canisters with bacterial dust. After being put into the can, the openings are in contact with the contents and consumed. The health of the drinkers will not be guaranteed.
In addition, the above two kinds of can lid pull ring is not very convenient at the time of opening, consumers have a peaceful experience that is when opening the easy open lid pull ring, mainly rely on the fingers of the finger cover force, this design does not meet The principle of user-friendliness that is convenient to use, from an ergonomic point of view, refers to the best endurance force when the flap is in the ring, and the finger force requires that the end of the loop have a snare's contact.
3 Easy to open the optimal design
Based on the above analysis, the author optimized the lid design. The pattern shown in Figure 3 is the optimized design of the lid. The design principle of the design application is similar to that of the retaining lid. The rivets are used as the fulcrum. The end of the pull ring is where the force is applied. The force is the top of the geothermal resource ring that pushes down the can lid. This design differs from the retention cap in that the rivets are on the heroic image piece so that when the pull tab is pulled up, the rivet is subjected to an upward force, the tearing piece is lifted under the action of the shear stress, and the tip of the tear piece and the can are The cover is connected for the connection line. In this way, it is possible to avoid complete separation of the tearing piece from the can lid. This design idea is accomplished by the shortcomings of full tearing and retaining can lids. The structure avoids the environmental pollution and wounding caused by the pull ring completely out of the can lid. The possibility also solves the problem that consumers' drinking health is not guaranteed. In addition, the design notices that the grooved end of the can lid at the end of the pull ring is deeper and deeper than the original design so that the consumer can use the background force instead of the lid when lifting the pull ring.
4 Conclusion
The optimization design proposed in this paper considers the factors of greenness, humanization and processing technology. Although the use of plastics and paper for beverage packaging has been widely used in recent years, the amount of metal cans used in the packaging of carbonated soft drinks, fruit juices, beer, etc. is still very large, and the packaging design of metal cans should be greener and more humane. Only in this way can we truly meet the needs of consumers.