Application of cutting and rewinding technology of

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The application of composite film slitting and rewinding process in flexible packaging

the slitting and rewinding process of packaging composite film actually refers to the further processing of composite products and more perfect different curve products through special machinery. The purpose is to facilitate the production of the next process, or to provide preparation for the next process. So we say that slitting and rewinding is an intermediate process, which plays a connecting role. In fact, the process flow is: composite film unwinding - composite film traction - slitting - product winding - finished product detection - finished product packaging or product reprocessing. Common composite structures include pet/al/pe, pet/vmpet/cpp, opp/cpp, opp/vmpet/pe, opp/pe, etc. When cutting different composite structures, the process parameters are set differently, which must be paid great attention to. In fact, many personnel engaged in the process do not understand the basic parameters of the materials to be cut, which eventually leads to errors in the process and direct losses of product scrap. In order to ensure the quality of slitting and rewinding, we require operators to have a full understanding of the process and a serious and responsible attitude. Slitting and rewinding equipment mainly includes electrical devices, slitting and rewinding devices, and air source devices. The following describes and analyzes the process problems from different angles:

slitting and rewinding device

(1): composite film unwinding device and its role

the unwinding device of composite film mainly includes: threading roller, core plug, sliding platform, magnetic particle brake, deviation corrector, etc. The function of the threading roller is: "The composite material to be cut is generally made of stainless steel solid. The diameter is mm, which requires a certain load capacity and does not bend or deform under 150kg. On the contrary, normal feeding and cutting cannot be carried out. With the improvement of current manufacturing, the diameter of the unwinding and threading roller has been changed and has been increased to 100mm. It is not difficult for us to find that the diameter of 100mm is similar to the current common winding core diameter of mm. At the same time, it is gratifying that there are many now The slitting and rewinding machine and unwinding of flexible packaging are also transformed from the original solid roll to the current air drum type. There are three advantages in analysis: "a-reduce the operating procedures and improve the production efficiency. B-improve the unwinding flatness and ensure the product slitting and rewinding. C-reduce the quality problems caused by the friction and crushing of the coil core during high-speed operation and improve the cleanliness of the product." The function of the core plug is mainly to stabilize the unwinding base material so that it can run smoothly. It is generally used on the solid threading roller. The plug shall be clean, otherwise it will shake left and right during unwinding, which is not conducive to slitting. The sliding platform plays a great role, not only supporting the threading roller, but also positioning with the electric eye tracking of deviation correction and the left and right swing of the unwinding film. Therefore, the sliding platform is the core part of the unwinding device. The sliding platform requires flexibility. Often, the lubrication part is poor, and the unwinding cannot operate normally, resulting in many quality problems, such as the uneven and jagged edges of the cut film. (as shown in Figure 1) the principle of the magnetic particle brake is to adjust electrically. The purpose is to control the tension of the unwinding film. The tension is adjusted by connecting the micro motor of the magnetic particle brake. CFRP is a kind of difficult to machine material, which is usually expressed by ammeter unit "a". The setting of the deviation correction instrument is also very important. Because the deviation correction setting is not good, and the unwinding and walking materials are misaligned, the cutting size of the product is unstable. You can imagine the scrap rate of the product. When setting photoelectric correction, the focal length of the electric eye should be fixed first. The specific method is: "first stick the composite film (preferably the black film) on the roller, let the long strip light of the electric eye project on the black film, adjust the distance between the electric eye and the black film (about mm), repeat the electric eye several times, the front indicator light will follow the change of red and green light, and the position of the electric eye should stay at the place where the indicator light is not lit (about 30mm). It should be Bairstow in 1910." The change of stress-strain curve under cyclic load is studied, the hysteresis loop is measured, and the concepts of cyclic hardening and cyclic softening are established; The program fatigue experiment was also carried out to remind the operator that the installation angle and focal length of the electric eye will affect the left and right balance of the signal. When setting sensitivity. If there is continuous jitter at the upper black film, it indicates that the sensitivity is excellent and suitable for the requirements of slitting. On the contrary, the sensitivity is weak. The deviation correction speed is not as fast as the synchronous speed of the main motor, and a quality accident occurs in slitting the composite film roll. " Therefore, the adjustment of deviation correction is often carried out when there is no slitting. Deviation rectifiers are widely used in flexible packaging. They can be installed on printing machines, laminating machines and bag making machines, which can improve production efficiency and product quality

(2): traction device of composite membrane

relatively speaking, the traction device is much simpler, mainly several rollers are installed at different positions. The requirement is that each traction drum can be flexible, clean and free of foreign matters. Each drum of the device is padded on both sides by lubricating bearings. Therefore, bearing oil shortage is often manifested as poor operation. Friction and longitudinal slip marks occur when slitting the composite film roll. Especially, it is obvious when the transparent structure is rewound. The surface of the drum should be smooth without thorns, otherwise the product will have periodic quality problems, such as marks and even perforation, under the high-speed state

(3): slitting device

the main parameters of the slitting device are: the selection of slitting blade, the angle adjustment of slitting knife, the treatment of residual film edge, the adjustment of slitting size, the discrimination of slitting quality, etc. There are two main points to choose the slitting blade: "A-- and double-sided. The selection is based on the structure and thickness of slitting and rewinding. If the thickness of the composite film is below 70UM, it is recommended to choose double-sided blade. UN recommends to choose single-sided blade. Because the double-sided blade is relatively soft and suitable for slitting thin materials, so that the flatness of the film edge can be guaranteed and the impact performance at low temperature. At the same time, it can also extend the service life. The single-sided blade is thick and rigid. It is better when slitting thick film. Because of the high-speed slitting Under normal circumstances, the hard blade is not easy to displace, so as to ensure the product quality. B-the blade edge should be sharp and free of notch. " The adjustment of the blade installation angle is very important, because now generally, the angle adjustment on the slitter is fixed manually, and only the screw is rotated. It is suggested that the angle should be 45 degrees. If the angle is too large, the tough edge of the blade cannot be fully used. If the angle is too small, you may worry about incomplete slitting and rough edges of the product. It needs to be reminded that the speed should be reduced to the slowest when installing the blade. Generally, normal operation can be carried out after debugging, and pay attention to safety. For the treatment of residual film edges, the slitter is now equipped with a hollow pipe, which is connected to 0.5 meters outside the machine. The tube is also a channel for residual film edge treatment. Because the film edge is light, the manufacturer is smart to install an electric hair dryer, and the film edge is blown away at a certain wind speed. The cutting size is adjusted according to the actual requirements, and finally meet the needs of customers. Generally, the slitting film edge is 0.5cm, which indicates that the composite manufacturer produces waste, and too little slitting brings difficulties. There are edge seal products, middle seal products and so-called automatic cutting products

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