Common tension problems and solutions in the hotte

2022-09-22
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Common tension problems and solutions in gravure printing production

release date: Source: Internet editor: lychee browsing times: 518 copyright and disclaimer

core tip: the tension control system of gravure printing machine realizes tension detection through the swing roller, and a tension detection potentiometer is installed at the end of the swing roller. When the tension changes, the detection value of the tension detection potentiometer will also change, At this time, the tension controller will obtain the deviation, and adjust the speed of the corresponding motor through the PID controller to keep the tension of the coil stable. In gravure production, factors such as the change of the running speed of the controlled coil, the change of the coil diameter, the change of the moment of inertia of the mechanical transmission system and the change of the mechanical loss will disturb the stability of the tension. The operation of the tension control system is directly related to the quality of gravure products. Once the tension is abnormal, it will affect the yield and cause a certain waste of materials

[China Packaging News] the tension control system of gravure press realizes the tension detection through the swing roll. A tension detection potentiometer is installed at the end of the swing roll. When the tension changes, the detection value of the tension detection potentiometer will also change. At this time, the tension controller will obtain the deviation, and adjust the speed of the corresponding motor through the PID controller to keep the tension of the coil stable. In gravure production, factors such as the change of the running speed of the controlled coil, the change of the coil diameter, the change of the moment of inertia of the mechanical transmission system and the change of the mechanical loss will disturb the stability of the localization rate of the tension equipment greater than 80%. The operation of the tension control system is directly related to the quality of gravure products. Once the tension is abnormal, it will affect the yield and cause a certain waste of materials. In this paper, the author summarizes several common tension problems and their solutions in gravure production, and is willing to share and exchange with insiders

question 1: how to establish a stable initial tension more easily

1. phenomenon

in the actual gravure production, the diameter and width of the roll of different printing substrates will be different. When the roll with smaller diameter is installed in the unwinding unit, the gravure machine can smoothly establish the initial tension of the whole machine, but if the roll with larger diameter is replaced, the swing roller of the gravure machine will vibrate frequently, and cannot stabilize for a long time, and the roll will be deformed in serious cases, Even these problems not only affect the insulation performance and service life of the external insulation system, but also stretch the coil

this situation will not only cause serious waste of materials, but also increase the workload of operators and bring many unnecessary troubles to printing enterprises

2. Analysis

the change of coil diameter will cause the change of its inertia, but before the gravure press establishes the initial tension of the whole machine, the position of the swing roll does not change, that is, the tension deviation collected by the tension controller does not change, and accordingly, the output of the tension controller does not change. However, for rolls with different diameters, the motor has the same angular speed, so the larger the diameter of the roll, the faster the surface linear speed. The faster the speed, the harder it is to control the motor. Therefore, for rolls with different diameters, the difficulty of establishing a stable initial tension of gravure press is different

3. solution

for coils with different diameters, different proportional units and integral units are set for the PID controller, so that the surface linear speed of coils with different diameters has little difference when establishing the initial tension. Specifically, for the coil with small diameter, set a larger proportional unit and integral unit, which will not affect the running speed of the motor when establishing the initial tension, but also establish a stable initial tension; For the coil with larger diameter, set smaller proportional unit and integral unit to slow down the running speed of the motor, so as to establish a stable initial tension

question 2: how to achieve a smooth transition of tension during automatic roll change and cutting

automatic roll changing and cutting, that is, under the action of tension controller, the duplex position axis can realize the automatic switching between new and old coils. The specific process is as follows: first, press the preparatory receiving button, and the rotary frame of the gravure press will rotate counterclockwise. Through the detection device, the new roll will be controlled to park at the predetermined position. At the same time, the potentiometer will detect the approximate diameter of the new roll, and drive the new roll to rotate at a certain surface linear speed, so that it is basically equivalent to the surface linear speed of the old roll; Secondly, press the receiving button, and the cutting device completes the pasting and automatic cutting of new and old rolls through corresponding actions; Finally, the old material roll is reduced from the current speed to zero speed to complete the cutting

automatic roll changing and cutting can not only improve work efficiency, but also reduce the workload and work intensity of operators

1. phenomenon

the automatic roll change and cutting process is carried out in the high-speed operation of the gravure press. Therefore, there are many influencing factors in the automatic connection and replacement of new and old rolls, which is easy to cause abnormal vibration of the swing roll, and the smooth transition of tension between the old roll and the new roll cannot be achieved. Once this problem occurs, it will take a long time to adjust the test method of the tensile testing machine to return to normal, resulting in a double waste of material and time

2. Analysis

in the process of automatic roll changing and cutting, the smooth transition of tension between the new roll and the old roll can be achieved only under the same surface linear speed, which requires the potentiometer to accurately detect the diameter of the new roll, so as to ensure that the surface linear speed of the new roll and the old roll is as same as possible, providing a prerequisite for the realization of automatic cutting

of course, it is only an ideal situation that the surface linear speed of the new and old reels is completely consistent. In fact, there is a certain speed difference between the two. Usually, after the automatic roll change and cutting is completed, the tension of the new reels will still change slightly, but it will not affect the quality of the final product

3. solution

in order to ensure the accurate detection of the diameter of the new roll, the potentiometer can be replaced with an encoder with higher accuracy. After the coil change is completed, the coil state has changed to some extent, which will bring some interference to its diameter detection, so the coil should be stabilized before detection. The proportional unit and integral unit of the roll should be more refined. When the diameter of the roll changes, the adjustment amount of the tension controller also changes accordingly, so as to reduce the tension fluctuation

constant tension control is the guarantee of product quality. When there is a problem in tension control, as long as you observe carefully and analyze carefully, you can find the corresponding solution

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