The hottest metal packaging can canning process 0

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Metal can making process

the traditional manufacturing method of metal can is: first cut the sheet metal blank into squares, then roll the blank into a cylinder (i.e. the cylinder), and then tin weld the formed longitudinal joint line to form a side seal. How will one end of the cylinder (i.e. the bottom of the tank) and the circular end cover be done by mechanical method? At present, it is unknown how to form a flange and roll the seal (i.e. double crimping joint), Thus forming the tank body; The other end is sealed with the tank cover after the product is loaded. Because the container is composed of three parts: the bottom, the body and the cover, it is called three piece can. This can making method has basically not changed much for more than 150 years, but the automation and machining accuracy have been greatly improved. In recent years, the welding seam of the side seal has been changed to fusion welding

A new can making principle appeared in the early 1970s. According to this principle, the can body and the can bottom are a whole, which is stamped from a round flat slab, and sealed after being loaded into the product, that is, a two-piece can. There are two forming methods for this kind of can: stamping thinning drawing method (i.e. punching method) and stamping re stamping method (i.e. deep drawing method). These technologies are not new in themselves. As early as the first World War, the punching method has been used to manufacture cartridge cases. The difference between can making and ultra-thin metal is that it uses ultra-thin metal and the production speed is high (the annual output can reach hundreds of millions)

1 manufacturing of three piece cans

the manufacturing process is: cut the coil into rectangular plates with a shear machine; Painting and costume printing; Cutting long billet; Roll into a cylinder and weld the side seam; Repair joints and coatings; Cutting cylinder; Forming grooves or waves; Press out flanges at both ends; Rolling back cover; Inspect and stack on the pallet

① barrel processing. The key process is curling forming and side seam welding. There are three sealing methods of side seam: tin welding, fusion welding and bonding

the tin solder of tin can is generally composed of 98% lead and 2% tin. The cylinder making machine that rolls the flat slab into a cylinder is used in pairs with the side seam sealing machine for tin welding. In the cylinder making machine, the edge of the slab is cleaned and bent into a hook shape, so that it is easy to fix when forming a cylinder. Then the cylinder passes through the side sealing machine, adds solvent and solder, preheats the sealing area with a gas gun, further heats the solder through the longitudinal tin welding roller, and then uses a rotary scraper roller to remove the excess solder that mainly exists in drops

fusion welding uses the principle of consumable wire electrode and adopts resistance welding process. Earlier fusion welding systems used large laps to raise the temperature of steel to the melting point and weld under low roller pressure. The latest welding machine adopts a small overlap amount (0.3 ~ 0.5mm), and the metal temperature is just below the melting point, but it is necessary to increase the pressure of the welding roller and forge the two overlapping surfaces together

the weld destroys the original or painted smooth surface of the inner surface, resulting in exposed iron, iron oxide and tin on both sides of the weld. In order to prevent the product from being polluted and the weld from being eroded by the product, the side seal needs to be protected by coating in most cases

the side seal of the tank containing only dry products can be glued. That is, paste the longitudinal joint with nylon tape, which melts and condenses after the cylinder is formed. Its advantage is that the original edge can be completely protected, but it can only be used in Wuxi Steel (TFs), because the melting point of tin is close to the melting temperature of plastic

② post processing of simplified Chinese. Flanges must also be machined at both ends of the shell in order to install the end cap. For processed food cans, the cans may be subjected to external pressure during processing or may be internally vacuum during storage. In order to increase the strength of the tank, stiffeners may be made on the surface of the shell. This process is called corrugation. In order to improve production efficiency, the length of the round Jane of the shallow container is often two to three tank lengths. At this time, the first process is to cut off the cylinder. The traditional practice is that the slab is cut continuously on the cutting machine (scoring machine) before forming. However, recently, due to the emergence of can trimming shears developed for the production of two-piece cans

2 manufacturing of two-piece cans

the two molding methods for manufacturing two-piece cans adopt the metal plate molding method. This method is based on the metal "fluidity" shown by the rearrangement of crystal structure under the action of composite stress, and the material should not fracture in this process

① stamping. That is to use a punch of the press to punch a flat plate into a cylindrical die, so as to deform the flat plate into a cylinder. The diameter of the cup formed after the initial stamping can be reduced by the re stamping process. In the re stamping process, a stamping sleeve is used to replace the stamping die and installed between the punch and the inner diameter of the cup. The equal area rule determines that the height increases with the reduction of diameter. The re stamping process can be repeated again. The diameter of the book gradually decreases within a certain limit, and the metal fracture is avoided

② thinning and stretching of cup wall. The stamped cylindrical cup is sleeved on the punch, and the punch is squeezed into a die along the axial direction. The gap between the die and the punch is less than the thickness of the cup wall, so that the wall thickness is reduced when the diameter remains unchanged. The metal volume of the cylinder after thinning is equal to the metal volume of the cup during thinning and stretching, and also equal to the metal volume of the original slab. In the manufacturing of cans, this process needs to be repeated twice or three times. The punch with cup passes through a series of molds successively, and one stroke passes through one mold. The most convenient way to install the punched forest on the punch is to conduct a re punching operation before the first thinning drawing

③ manufacturing of cupping. The manufacturing process of cupping is generally as follows: unfold the ordinary strip coiled material; Xu lubricant; Blanking and cup flushing; Re stamping; Thinning and stretching of cup side wall; Bottom forming; Cut the edges of simplified Chinese according to the correct height; Cleaning and disposal. For dry drink cans, the outer surface coating, printing and decoration, inner surface coating, flange forming and closing of the open end are also required. For food cans, the outer surface coating, flange forming at the open end, cylinder pressure ripple and inner surface coating are carried out during the cleaning process, or the can end is made of pre coated plates on a multi mold press, and the can cover is pressed with ripples (stiffeners) to bear the internal and external pressure. The last process here is curling to form and print the double curling seam of the report (see Figure 1). Place packing on the final seal to act as a sealing gasket

Figure 1 double crimping and sealing

1-end cap crimping and folding on the flange of the cylinder 2-sealing filler 3-sealing overlap 4-cylinder 5-end cap

④ manufacturing of deep drawing tank. The steps of manufacturing the deep drawing tank are as follows: cut the thin plate and strip coil into vortex shaped plates; Coating and finishing plate (coil can also be coated); Disc blank blanking and cup punching; Re flushing (once or twice, depending on the size of the tank); Tank bottom forming; The flange is trimmed to the correct width; Inspection and sterilization treatment

as with the drawing process, a multi die cup punching machine is used to load and unload the wide sheet coil or plate, and punch it into a shallow cup

the shallow cup gradually reduces its diameter and increases its height through primary and secondary re stamping. When the final stamping is stopped to a certain extent, a flange will be left on the can, like all other sheet metal forming processes. Irregular edges should be cut off, and the tank bottom should be processed into the required shape

processing equipment

the main equipment for can making processing includes various stamping machines, shear blanking machines and other auxiliary equipment. There are many kinds of these devices, which are impossible - an introduction. In view of the characteristics of automatic production in modern can making industry, this chapter only takes the composition of the cupping production line (Figure 2) as an example for a brief description

Figure 2 composition of the cupping production line when we bought the computer

l- coiler 2- coil selection inspection and lubricant coating equipment 3- single side thinning and stretching machine of the washing machine (making simplified Chinese) 5-cutting machine

6-can cleaner 7-outer surface coating equipment 8-Box furnace 9-filling equipment 10-box furnace 11 obstruction return flange forming machine

12-inspection machine 13 internal spraying machine 14 curing furnace 15 local secondary spraying 16 curing furnace

thin plate coil is sent to the exhibition by transport vehicle. Common fault 7: coiler (roll stand). The coiler generally has two arms, one of which is facing the thin plate coil transport vehicle, and the other arm feeds the press. The thin plate coil can be replaced by rotating the arm. The thin sheet roll is coated with lubricant on both sides through the lubricant coating equipment, and passes through a pair of rubber rollers to remove the excessive lubricant. In the older production line, the lubricant is mixed into the correct concentration and then stored in a container, which is supplemented to the lubricant groove when necessary. In newer production lines, an external circulation system is generally used, which can control the temperature, continuously filter and maintain the constant quality of lubricating oil

cup punching press is a specially designed double action press, which first punches several round slabs, and then punches the round slabs into shallow cups. These two actions are completed in one trip

the function of the cup wall thinning and drawing machine is to turn the cup into a cylinder with the correct thickness distribution of the side wall, and turn the cup bottom into a design shape that can resist internal pressure in use. Here, the cup is re punched and left on the punch, and then the cup wall is thinned through three thinning drawing rings in turn. At the end of the journey, enter the auxiliary press to form the round arch and cup bottom. At the beginning of the return journey, with the help of the compressed air sent by the punching pipe, the spring ejector rod will unload the can body from the punch, and the can will be sent out of the machine by the conveyor belt

each cup wall thinning and drawing machine works together with an edge cutting machine. There are two forms of edge cutting machine, guide rail type and roller type. Many cores are installed on the rotating frame of the guide rail trimming machine, and the can edge is cut between the rotating core and the static guide rail. On the roller trimming machine, one end of the tank is sent between the two rollers and rotates around its own axis, and the two rollers are close to each other to complete the trimming action

after the tank is cut at a fixed height, the opening of the tank is facing down, buckled on the lattice conveyor belt, and is largely transmitted to a series of cleaning rooms equipped with spray nozzles. The lubricant used in punching and thinning stretching is washed away with detergent, and finally rinsed in non ionic water to ensure that there is no stain and dry

the closing and flange forming machine is used for closing and flange forming of beverage cans, while for food cans, it is used for crimping and flange forming. In order to avoid roughening the axial surface of the metal during thinning and drawing, the flange is generally formed by spinning process. The necking at the top of the beverage can can be retracted and formed with a mold after spinning the flange. (end)

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