Analysis of the status and operation problems of t

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Analysis of the status and operation problems of domestic aluminum foil slitting machine

1 status of aluminum foil slitting equipment

after the aluminum foil for drug packaging is processed on the special aluminum foil printing coating machine, the semi-finished products need to be cut on the slitting machine, and its length, width and weight need to be determined according to the relevant standards. At present, the performance technology of foreign post press slitting machines is superior to that of domestic ones, mainly in the following aspects: first, the equipment technology is more advanced, using shaftless unwinding, photoelectric deviation correction and pneumatic braking. The reeling adopts independent center reeling, equipped with upper and lower friction reeling shafts. The reeling shaft adopts a special structure, which is assembled by air bag felt strips and many friction rings. The reeling paper core is fixed on the friction ring, and there is no contact pressure between the friction rings, which can ensure the reeling of aluminum foil products of multiple sizes on the same shaft. The control series of the slitter adopts the world's latest PLC and touch screen, with automatic control functions such as inertia and friction pressure calculation, working speed winding tension characteristic curve calculation, etc. When calculating the winding tension by PLC, the diameter, speed, moment of inertia and other factors are comprehensively considered, which can ensure that the winding tension control is accurate and stable, and has the function of fault display, and the operation is simple. Secondly, the slitting speed is high, and the slitting speed is as high as M/min. it is equipped with a special coil unloading device, which is convenient, time-saving, high production efficiency and high degree of automation. The operation of the slitter is basically completed on the touch screen, with high quality assurance and good repeatability of slitting and winding, which eliminates the influence of human factors such as the experience and skills of operators. A machine can be used for many purposes. About 20000 winding tension diameter characteristic curves and winding tension speed characteristic curves are stored in the machine for selection. After selecting various parameters of the curve and equipment, the winding tension can be automatically controlled, so the machine has a wide range of adaptability. In addition to slitting aluminum foil, it is also suitable for slitting PE, PP, PVC and other plastic films to meet the needs of different industries

compared with foreign equipment, the domestic medicinal aluminum foil slitter is still at a low technical level, mainly in several aspects: the slitting speed is low. Generally, the nominal maximum speed of domestic machines is 180m/min, but the actual speed is less than this speed; The slitting and winding quality is unstable. Due to the backward control mode of domestic machines, low control accuracy, poor stability and repeatability, the quality of slitting and winding is unstable and highly dependent on the experience and skills of operators. When cutting products with different widths, the winding length cannot be accurately guaranteed. After the efforts of recent years, with the rapid development of pharmaceutical packaging and market changes in China, the production capacity of slitting equipment continues to increase, and the product quality needs to be further improved. According to the current use situation, summarize the performance requirements of enterprises for the slitter in use, and need to improve in the following aspects:

1. Improve the production capacity of the slitter. Generally, the unwinding diameter is about 1000mm, and the winding diameter can reach 600mm

2. Improve the slitting speed. On the basis of the current cutting speed, it will be increased to 200-00m/min. Improving slitting speed is the main way to improve production capacity, and high speed is one of the main means for enterprises to increase output and reduce costs

3. Easy to operate. The increase of the diameter of the original coil will inevitably increase the labor intensity for the operator, and the requirement of reducing the labor intensity must be put forward for the equipment. The unwinding system is divided into axial unwinding and shaftless unwinding. Generally speaking, shaftless unwinding is convenient for winding up and clamping. As long as a lifting car is used, winding up and unloading can be convenient to use, so as to achieve the purpose of reducing labor intensity. The control operation must also be simple and intuitive, such as setting tension, tension curve, unwinding diameter, slitting material and thickness, rewinding width, length and other parameters, which can be achieved through simple operation, using equipment to ensure the rewinding quality and eliminate the influence of human factors

4. the equipment is safe and reliable. When the equipment is running at high speed, there should be a certain guarantee for the safety of operators and the safety of the action sequence of the equipment; The deviation corrector is sensitive to ensure that the edge of aluminum foil is neat without staggered layers; The meter setting is stable to ensure that the winding length deviation is within a certain tolerance range

2 factors affecting product quality during the operation of domestic slitting machine

after printing and coating, aluminum foil needs to be cut on the slitting machine after printing, and the large volume of semi-finished products will be cut into the required specifications and sizes. The substrate running on the slitter is a process of unwinding and rewinding. This process includes speed control and tension control of the machine. The so-called tension control is to pull the aluminum foil and roll it onto the roll core according to the standard. A certain tension and tension traction force must be applied to the aluminum foil, of which the tension control force is the tension. If the tension is too large and the winding is too tight, the aluminum foil is easy to wrinkle; If the tension is insufficient, the aluminum foil is easy to slip on the mandrel and be seriously misaligned, so that the coil cannot be unloaded, and the unwinding shaft swings greatly during slitting, affecting the slitting quality. Therefore, the slitter must have a good tension control system

1. detection system type of winding tension and speed of slitter: ① tension sensor detection: the tension sensor is installed under the bearing of the tension detection roller, converts the detected aluminum foil tension into an electrical signal, sends the tension signal to compare, carries out PID calculation, and then inputs it into the winding motor controller to control the tension and speed of the winding roller. ② Floating roll indirect tension detection system: a set of floating rolls is installed in front of the aluminum foil tracking roll, and the position of the floating roll is detected by a potentiometer. The way of tension control is to keep the tension constant by maintaining the position of the floating roll as unchanged as possible. ③ The magnetic particle clutch is used to control the rotating torque of the input winding roll to achieve tension control: the magnetic particle clutch is composed of the driving part and the driven part, which are connected with the winding roll through the universal coupling and other transmission mechanisms, and the middle is filled with micro iron magnetic particles as the torque transmission medium. A certain current is passed through the excitation coil to form a magnetic field, and the magnetic particles are magnetized. The magnetized magnetic particles attract each other to form a chain arrangement. When the active part rotates at a constant speed, it destroys the coupling force between the magnetic particles and forms a circumferential tangential force. The product of the tangential force and the radius of the magnetic particle circle is the rotating torque that drives the winding of some steel plates and even half tensioned parts, so as to realize the coupling of the output torque from the active part to the driven part in continuous rotation, so as to achieve the purpose of controlling the tension. ④ Slitting and unwinding capacity and speed detection system: the magnetic powder tension brake is mainly used to control the unwinding force and speed. Its working principle is that the magnetic powder brake is equipped with a coupling, as well as input and output components with magnetic coils. Under the magnetic coil is an annular groove, and under it is an annular rotor, that is, the output part. The annular groove is located in the center of the output part, and the groove is filled with magnetic powder. When there is excitation current in the magnetic coil, the coil will generate magnetic flux to make the magnetic particles arrange along the direction of the magnetic field, which will generate resistance between the input part and the output part and transfer the torque. If you want to increase or decrease the tension and speed applied to the aluminum foil, you can effectively control the tension and speed as long as you change the size of the excitation current, or change the current value that the amplifier will add the experimental force to the coupling coil

2. attenuation of winding tension and tension compensation: it is generally believed that maintaining the constant tension of aluminum foil during winding is conducive to the apparent quality of aluminum foil finished products, but it is not. The best way is to increase the tension of the aluminum foil according to a certain law with the increase of the coil diameter, and the smaller the diameter is, the lower the tension value will be. There are automatic tension control and manual tension control in the process of slitting operation. The automatic tension control system is a preset tension value, which is maintained throughout the winding process. Manual tension control requires the operator to constantly adjust the diameter of the substrate roll to meet the tension required by the aluminum foil during operation. When setting the automatic tension operation, the initial tension should be set first, and then the tension attenuation value should be set. Taking the setting of the attenuation value of slitting and unwinding as an example, the setting principle is: the aluminum foil tension attenuation value (%) is equal to the tension at the end of winding of each roll of aluminum foil minus the initial tension, and then divided by the initial tension, and the quotient obtained is multiplied by 100%. When setting the automatic tension value of unwinding, it should not be too large, otherwise the surface hardness of aluminum foil winding is large, and edge warping is easy to occur. However, the tension should not be too small, which is easy to cause too loose rewinding body, irregular winding and edge running. Therefore, the quality of rewinding and unwinding during aluminum foil slitting operation is mainly affected by the change of aluminum foil tension. It can be seen that the mastery of rewinding and unwinding control system is the key to affect the quality

3. The change of speed during slitting affects the change of tension: when the operation is accelerated or decelerated, the speed of the main motor changes. Firstly, it causes the instantaneous change of the tension of the aluminum foil from the unwinding traction to the winding section, and the aluminum foil must vibrate slightly for a period of time to gradually stabilize the tension. The instability of this tension is manifested in the uneven winding of the finished coil, and the concave convex phenomenon on the end face, which affects the product quality

4. The estimated maximum load accuracy of the tension detection roller of the slitter: if the processing accuracy of the detection roller is poor during operation, the stability of the tension of the aluminum foil cannot be guaranteed, which will affect the product quality. The overall requirement for the inspection roll is that the circular runout of the roll during processing should not be too large. If the runout is too large, the tension of the aluminum foil will change irregularly with the rotation of the roll. In addition, the balance of the roll is not good, and the speed of the roll will change all the time in a week. The requirements for roll balance are: the eccentric weight at the outer diameter should not exceed 5g, which is used to rotate the guide roll. After the hand is released, the guide roll rotates smoothly and stops. It can stop at any position. The roll weight should be as light as possible, and the moment of inertia should be as small as possible, so as to be consistent with the speed of the host

to sum up, when implementing the first development project of the industrial development plan to cut medicinal aluminum foil, we should first choose advanced models, and pay attention to the understanding of which winding tension control system is used in the equipment during operation. According to the characteristics of the tension detection and control system in the equipment, we should formulate a reasonable tension for the aluminum foil materials used and the tension attenuation and compensation in the winding process, so as to realize the soft start of the tension of the equipment, Soft stop to prevent quality problems. In the process of slitting operation, we should always pay attention to the change of aluminum foil winding tension, because it is affected by the change of material quality, weight, thickness uniformity and slitting speed. When setting the winding tension, we must adapt to these characteristics of aluminum foil. In order to ensure the accuracy of the winding tension, the dynamic balance treatment shall be carried out when the tension detection roller of the winding mechanism should be higher than the maximum speed per hour, and its surface should have enough wrapping angle when in use, so as to provide accurate running tension and ensure the stability of product quality. (text/Bai Bing)

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