Aluminum foil cutting quality
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After the aluminum foil for pharmaceutical packaging is processed on a special aluminum foil printing and coating machine, the semi-finished product needs to be cut on the slitting machine, and the length, width and weight thereof are determined according to relevant standards. At present, the performance technology of foreign post-press slitting machines is superior to that of domestic ones. The main performances are as follows: Firstly, the equipment technology is advanced, mainly in the use of shaftless unwinding of raw materials, photoelectric correction air pressure braking method, and the winding center adopts independent center collection. The roll is equipped with two upper and lower friction winding reels. The reel is made of special structure and assembled by airbag felt strip and many friction rings. The winding paper core is fixed on the friction ring, and the friction ring has no contact pressure with each other, and the aluminum foil product of the multi-roll size can be ensured on the same shaft. The control system of the slitting machine adopts the latest DLC and touch screen, and has automatic control functions such as inertia and friction air pressure calculation working speed winding tension characteristic curve calculation. When pLC calculates the winding tension, it takes into account factors such as diameter, speed, and moment of inertia to ensure accurate and stable tension control, and has a fault display function and is easy to operate. Secondly, the cutting speed is high, the cutting speed is as high as 300-400m/min, and it is equipped with a special unloading device. The loading and unloading rolls are convenient, time-saving, high in production efficiency and high in automation. The operation of the slitting machine is basically completed on the touch screen, and the repeatability is good, which eliminates the influence of the operator's experience, skills and other human factors. A machine has many uses, and the machine stores about 20,000 winding tension diameter characteristic curves and winding tension speed characteristic curves. After the variogram is selected and the various parameters are set, the winding tension is automatically controlled. Therefore, the machine has wide adaptability. In addition to slitting aluminum foil, it is also suitable for cutting plastic films such as PE, pp and pvc to meet the needs of slitting products in different industries.
Compared with foreign equipment, the domestic medicinal aluminum foil slitting machine is still at a relatively low level of technology. It is mainly displayed in these aspects: the cutting speed is low, and the nominal speed of the domestically produced machine is 180m/mim, and the actual vehicle speed is less than The speed. The quality of the slitting and winding is unstable, because the domestic machine control method is backward, the control precision is low, the stability and repeatability are poor, resulting in unstable winding quality during slitting, and strong dependence on the experience and skills of the operators. When slitting different products, the length of the winding cannot be accurately guaranteed. However, after the efforts of recent years, with the rapid development of pharmaceutical packaging in China and the changes in the market, the production capacity of slitting equipment has been continuously enhanced, and the quality of products needs to be further improved. According to the current situation of use, the manufacturers are generally in use. For the performance requirements of the slitting machine, it is necessary to re-elect in the following aspects to improve the production capacity of the slitting machine. Generally, the unwinding diameter is about 1000 mm, and the winding diameter can be up to 600 mm; 7 increasing the slitting speed. Based on the current slitting speed, it is increased to 200-300/min. Increasing the cutting speed is the main way to increase production capacity. High speed is one of the main means for enterprises to increase production and reduce costs; 3 easy to operate. The diameter of the original roll is increased, which is labor intensive for the operator, and the equipment must be required to reduce the labor intensity. The unwinding system is divided into a shaft unwinding and a shaftless unwinding. Generally speaking, there is no shaft unwinding, and the upper winding is convenient to clamp. As long as a lifting truck is used, the winding and unwinding can be used to achieve the purpose of reducing labor intensity. Control operations must also be simple and intuitive, such as setting tension, tension curve, unwinding diameter, slitting material and thickness, and winding width and length, all of which can be achieved by simple operation, and the quality of the winding is ensured by the precision of the equipment. Eliminate the influence of human factors; 4 equipment is safe and reliable. When the equipment is running at high speed, the safety of the operator and the safety of the sequence of the equipment should be guaranteed. The corrector is sensitive, ensuring that the edge of the aluminum foil roll is neat and error-free. The number of meters is set to be stable, and the deviation of the winding length is within a certain tolerance.
After the aluminum foil is printed and coated, it needs to be cut and cut on the slitting machine to cut the large-volume semi-finished product into the required size. The semi-finished product that is cut and run on the slitting machine is a process of unwinding and winding. This process includes two parts of the machine's running speed control and tension control. The so-called tension is to pull the aluminum foil and roll it onto the core according to the standard. It is necessary to apply a certain tensile and tensioning traction to the aluminum foil, wherein the tension of the aluminum foil is the tension. Tension control is the ability to permanently control the tension of the foil as it is transported on the equipment. This control must be effective for any operating speed of the machine, including acceleration, deceleration and uniform speed of the machine. Even in the case of an emergency stop, it has the ability to ensure that the aluminum foil does not break. The tension control of the slitter is basically manual tension control and automatic tension control. Manual tension control means that during the winding or unwinding process, when the winding diameter changes to a certain stage, the operator adjusts the manual power supply device to achieve the purpose of controlling the tension. The automatic tension control is to directly measure the actual tension value of the material belt by the tension sensor, and then convert the tension data into a tension signal and feed it back to the tension controller. By comparing the signal with the preset tension value of the controller, the control signal is calculated. The control unit is automatically controlled to make the actual tension value equal to the preset tension value for the purpose of stabilizing the tension. The size of the equipment winding and unwinding tension directly affects the yield of the product. The tension is too large, the winding is too tight, the aluminum foil is prone to wrinkles, I tension is insufficient, and the aluminum foil is easy to cause a serious misalignment on the roll, which may result in failure. Unloading, and causing a large swing of the reel when cutting, affecting the quality of the slitting, so the slitting machine must have a good tension detection system.
1. Slitting machine unwinding tension detection system:
(1) The tension sensor detects that it is a direct detection of the tension, and is closely combined with the machine, and is provided with a detection method of the moving part. Usually two sensors are paired and mounted on the end shafts on both sides of the detection guide roller. The strip detects displacement of the sensitive element of the tension sensor by detecting the applied load on both sides of the guide roller, thereby detecting the actual tension value, and converting the tension data into a tension signal and feeding it back to the tension controller.
(2) Indirect tension detection system of floating roller: a set of floating roller is installed in front of the aluminum foil tracking roller. The position of the floating roller is detected by a potentiometer. The tension control method is to maintain the tension constant by maintaining the position of the floating roller.
(3) The magnetic powder clutch is used to control the rotational torque of the input winding roller to achieve tension control: the magnetic powder clutch is composed of an active part and a driven part, and is connected to the winding roller through a transmission mechanism such as a universal joint, and is filled with fine iron in the middle. Magnetic powder is used as a torque transmission medium. A magnetic field is formed by applying a constant current to the exciting coil, and the magnetic powder is magnetized. The magnetized magnetic powder attracts each other to form a chain arrangement. When the active part rotates at a constant speed, the coupling force between the magnetic powders is broken to form a circumferential tangential force, and the product of the tangential force and the radius of the magnetic powder ring is the driving driven part. The winding torque of the winding realizes 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) The slitting and unwinding capability and the speed tension detecting system mainly use the magnetic powder tension brake to control the unwinding speed. The working principle is that the magnetic powder brake is equipped with a coupling, and the input part and output with the magnetic coil. component. Below the magnetic coil is an annular groove, the underside of which is an annular rotor or output member. The annular groove is located at the center of the output member, and the groove is filled with magnetic powder. When there is excitation current in the magnetic coil, the coil generates magnetic flux to align the magnetic powder in the direction of the magnetic field, thus generating damping between the input member and the output member, and transmitting the torque. If the tension and speed applied to the aluminum foil are increased or decreased, the magnitude of the exciting current can be changed, or the current value or voltage value applied to the coupling coil by the varying amplifier can be effectively controlled.
2. Attenuation and tension compensation of the tension and retraction of the slitting machine: It is generally believed that maintaining the constant tension of the aluminum foil during the rewinding and unwinding of the aluminum foil is beneficial to the performance quality of the finished aluminum foil, but it is not. The best method is to increase the tension of the aluminum foil according to a certain rule as the diameter or weight of the coil increases, and the smaller the diameter weight, the lower the tension value. Due to the automatic tension control and manual tension control in the slitting operation. Manual tension control requires the operator to continuously adjust to the weight of the master roll diameter. As shown in the following table:
Aluminum foil cutting weight (kg) Manual control power supply voltage value (V) Actual tension value (N)
30 5 15-20
60 6 20-25
90 6.5 25-30
120 7 30-35
150 7.5 35-40
180 8 40-45
210 8.5 45-50
The automatic tension control system is a pre-set tension attenuation value, which is attenuated according to the change of the material during the operation of the equipment. When setting the automatic tension operation, set the initial tension and then set the tension attenuation value. Taking the attenuation value of the unrolled aluminum foil unwinding as an example, the setting principle is: the aluminum foil tension attenuation value (%) is equal to the tension of the aluminum foil at the end of winding, minus the initial tension and then divided by the initial tension, and the result is multiplied by 100%. When setting the automatic tension value, it should not be too large. Otherwise, the aluminum foil winding surface has high hardness and is prone to curling, but the tension should not be too small. Too small is easy to cause the rewinding body to be too loose, and the winding is not neat. Therefore, the quality of the rewinding and unwinding during the aluminum foil slitting operation is mainly affected by the change of the tension of the aluminum foil. It can be seen that the mastery of the retracting and unwinding control system is the key to affecting the quality.
3. The standard requirements for the quality of the aluminum foil after cutting, the quality of the appearance requires that the surface of the cut aluminum foil is clean, flat and evenly coated. The surface and end surface of the cut aluminum foil should be tightly wrapped and the end surface is flat. No tower shape or split layer is allowed. If the loose layer or the core is free to fall off, the length of the aluminum foil should be controlled within 1000 m ± 2%. The number of joints per roll is less than or equal to 3/1000 meters. The flatness of the winding surface is less than 1 mm.
4. The change of speed affects the change of tension when cutting: When the speed is increased or decelerated, the speed of the main motor changes, firstly causing the instantaneous change of the tension of the unwinding traction to the aluminum foil of the winding section, and the aluminum foil must be slightly vibrated after a period of time, gradually making the tension smooth. Since the running speed of the equipment is operated by humans during the slitting operation, the speed of the operation will affect the flatness of the end face of the aluminum foil after slitting. Therefore, the slitting operation adopts a rapid speed-up operation, that is, the machine is reached in a very short time in a few seconds. The maximum speed at this time, the tension changes greatly at this time, when other problems occur, it is necessary to rush to stop the treatment, often buried the quality hazard, and another operation is to gradually speed up, also known as the segmentation speed: start at 30-50 m / min , gradually speed up to 80-100 m / min, and finally reach the maximum speed of the machine. It is called soft start, which is good for tension stability. Although the slit end face has a speed-increasing interface, the split surface is flat.
5. Reasonable installation of the slitting knife affects the quality: After the aluminum foil is printed, it needs different specifications and dimensions, and it needs to be cut on the slitting machine. The cutter used for slitting is a round knife and a round pad type, which is called a shearing cutter. Since the knife edge is precisely machined on a circular outer surface as required, when the upper and lower rollers rotate one turn, the slitting cutter line works correspondingly. For each cutting point, the cutting is performed under the rotation of the knife. The contact of the object line. The working principle is similar to that of a pair of scissors, and the cutting effect of the aluminum foil is achieved by the two opposite cutting edges of the upper and lower rollers. When the slit is large at the upper and lower cutting edges, the aluminum foil is not easily cut, and occasionally it can be cut, and the uneven surface of the end face is not obvious. The gap between the upper and lower edges is small, and the surface of the aluminum foil has a longitudinal texture. Generally, when the tool is loaded before cutting, the gap between the lines is adjusted to 0, 20-0, and 0.3 mm. In order to ensure the flat surface of the aluminum foil, the aluminum foil rebound and impact can reduce the metal collision and contact between the upper and lower cutter rolls during the slitting process of the aluminum foil. From the cross section of the cutter, the slitting is performed by the lower roller cutter. One side, thus improving the mechanical strength of the knife edge, as long as the use is reasonable, the knife edge collapse phenomenon will rarely occur.
6. Slitting machine tension detecting roller accuracy: If the processing precision of the detecting roller during operation is poor, the stability of the aluminum foil slitting tension cannot be ensured, thereby affecting the product quality. The overall requirement for the detecting roller is that the rounding of the roller during processing is not too large, the jumping is too large, and the tension of the aluminum foil changes irregularly with the rotation of the roller. In addition, the balance of the roller, the balance is not well mastered, and the speed of the roller changes within a week. The requirement for the balance of the roller is that the outer diameter should be more than 5 grams, and the guide roller should be turned by hand. After the hand is released, the rotation of the guide roller is smooth, so that it stops, and the roller can be stopped at any position. Keep it as small as possible to keep up with the speed of the machine.
In summary, when cutting the medicinal aluminum foil, first select the advanced model, and pay attention to understanding the characteristics of the retractable tension detection control system used in the equipment during operation, and make reasonable use of the aluminum foil material used. The tension and the tension decay and compensation of the rewinding process to achieve soft start and soft stop of the device tension to prevent quality problems. During the slitting operation, attention should be paid to the change of the tension of the aluminum foil rewinding and unwinding, because it is affected by the material quality, weight, thickness uniformity, and slitting speed. It must be related to the characteristics of the aluminum foil when setting the tension of the rewinding and unwinding. adapt. In order to ensure the accuracy of the tension of the rewinding and unwinding, the dynamic balance treatment should be carried out under the condition that the tension detecting roller of the rewinding and unwinding mechanism should be higher than the maximum speed, and the surface should have sufficient wrap angle to provide accurate running tension. Guarantee the stability of product quality.