The production of aluminum caps first requires cylindrical stretching of the aluminum plate, which is a stretching method with a edge ring. At present, the commonly used edge-holding method in the aluminum cap industry is to compress the rubber ring or spring to provide the edge-holding force. Due to the compression characteristics of the rubber ring and spring, during the compression process, the edge-holding force provided has a changing process, that is, it is first small and then large. , resulting in uneven wall thickness on the side of the stretched aluminum cylinder. Moreover, rubber rings and springs are prone to failure after repeated compression, and the blank holder force is unevenly provided, affecting product quality.

Aluminum lids are widely used in liquor, health wine, medicine, wine and condiments due to their good sealing performance, low cost, energy saving and environmental protection, high food safety, and low storage requirements for sealed products. Airtight sealing of the product. Aluminum cover processing first requires a special mold to stretch and deform the aluminum foil sheet into a cylindrical shape. Due to the small stretch coefficient and high product dimensional accuracy requirements, it usually requires edge stretching. At present, aluminum cover manufacturers generally use rubber rings or spring edge pressing methods. The blank holder force provided by the rubber ring and spring during the compression process changes from small to large, which is not conducive to stretching. Moreover, rubber rings and springs are prone to failure after repeated compression, and the blank holder force is insufficient or uneven, affecting product quality. ?

1. Research on pneumatic edge pressing of aluminum cover one-time stretching mold?

1. Current status of aluminum cover one-time stretching die edge pressing?

Currently aluminum The one-time stretching mold for the cover generally adopts the rubber ring edge pressing method. The rubber ring is connected in series to the screw and is isolated by a flat metal disc. The screw is screwed onto the lower template directly below the center of the punch, and the bottom of the screw is tightened with a nut. The blank holder ring of the mold is connected to the rubber ring through three ejector pins passing through the template, thereby forming a structure that provides blank holder force. Different blanking sizes require different blank holders, which can be adjusted through the fastening nut under the screw. The rubber ring edge pressing method is shown in Figure 1. ?

Disadvantages of the rubber ring edge pressing method: 1) During the stretching process of the aluminum cylinder, the edge pressing force is first small and then large, which is not conducive to deformation and stretching. 2) The rubber ring is prone to failure after repeated compression. 3) The three ejector rods passing through the lower template are easy to wear the lower template during work, and the holes are too large, causing the blank holder force to become unstable. 3) The rubber ring forms a long "tail" under the lower template, which makes loading and unloading the mold inconvenient and labor-intensive. ?

2. Design and application of pneumatic blanking of aluminum cover one-time stretching mold?

How to overcome the shortcomings of the rubber ring blanking method requires changing the method of providing blanking force. The following is the design of the pneumatic edge press, see Figure 2. ?

1.Punch 2.Blank holder 3.Blanking knife 4.Base 5.Sealing ring 6.Sealing ring 7.Piston 8.Sealing ring 9.Lower template 10.Compressed air channel?

The piston 7 and the base 4, and the piston 7 and the punch 1 mold handle are sealed with small resistance and wear-resistant sealing rings, and the sealing ring 8 is used between the base 4 and the lower mold boring hole. It is sealed in a way, thereby forming a closed space between the piston, the base, the punch mold handle and the lower template. It is connected to the external compressed air through the compressed air channel 10. The compressed air pushes the piston upward to connect with the blank holder, so that the pressure The edge ring's edge holding force can be provided and adjusted by compressed air. ?

Apply grease to the piston to reduce friction and improve sealing. The compressed air is provided with a gas storage tank of appropriate size to ensure the stability of the compressed air pressure in the mold. ?

Advantages of pneumatic blanking: 1) The blanking force is always consistent during the stretching process, thereby ensuring uniform wall thickness of the aluminum cylinder after stretching and high homogeneity of the produced product. 2) The structure is reasonable, the sealing ring is wear-resistant, has a long service life, and the mold is stable and reliable in use. 3) The long "tail" formed by the rubber ring pressure is removed, the mold is easy to assemble and disassemble, the labor intensity is low, and the safety is high. ?

2. Research on pneumatic edge pressing of two- and three-time stretching molds for aluminum covers?

1. Current situation?

At present, two- and three-time stretching of aluminum covers Molds generally use spring edge pressing, as shown in Figure 3. In order to facilitate cap removal, the drawing die is in the form of an inverted drawing die. When stretching the aluminum cylinder, spring compression is relied on to provide the blank holder force. The defects of the spring blank holder are: 1) The blank holder force is first small and then large, which is not conducive to stretching and is prone to wrinkles or cracks. 2) The size of the blank holder force is directly related to the thickness and compression amount of the selected spring. An appropriate spring must be selected. 3) The spring is prone to failure after repeated compression, causing product quality problems. ?

2. Design and application of the second and third pneumatic blanking stretching molds for aluminum caps?

The pneumatic blanking method overcomes the defects caused by the blanking force provided by the spring. The pneumatic edge-pressing method of stretching the mold is shown in Figure 4. ?

1. Cylinder 2. Blanket holder 3. Air storage tank 4. Compressed air channel?

The principle is basically the same as the above-mentioned pneumatic blank holder of the one-time stretching mold. In the cylinder 1. There is a built-in piston block, which forms a closed space between the cylinder, template and punch mold handle. Compressed air is introduced from the compressed air channel to provide pressure to the piston. The piston is connected to the blank holder and pushes the blank holder forward. This forms a process in which compressed air provides blank holder force. ?

Add a gas storage tank outside the compressed air channel. The gas storage tank has a pressure gauge and the pressure is adjustable. The compressed air pressure in the cylinder is adjusted through the air pressure valve to maintain appropriate pressure for the blank holder. Constant blank holder force.

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3. New development of pneumatic blanking stretching dies?

In order to further improve the efficiency of the secondary and tertiary aluminum cylinder stretching and break through the limitations of using special punches, a rotating structure is stretched. ?

The cylinder is suspended on the rotating body, and the upper and lower guide rails are used to precisely correspond to the die. The cylinder runs on the curved slide rail, and completes the up and down movements while rotating to realize the aluminum cylinder stretching process. The primary aluminum cylinder feeding method uses an indexing dial to ensure accurate feeding position. This kind of air pressure edge structure can increase production efficiency by more than 3 times. ?

3. Conclusion?

The design research practice has proved that the aluminum cover stretching mold using pneumatic edge pressing has high reliability and the quality of the products produced is better than that using rubber rings or springs. The products are produced by edge pressing and can be adapted to the production of rapid punches. It has a simple structure and strong practicability, and can be widely used in drawing molds for aluminum cover production.