Application Of Tension Controller In Gravure Equipment Manufacturing

With the development of China's gravure equipment manufacturing industry, the tension controller has also been used in further applications. China's gravure printing equipment manufacturing industry has experienced a rapid development process in recent years, and has achieved remarkable progress. With the rapid development of gravure printing machine color control technology and automation, some high-end computer color gravure printing machines in China Microcomputer control systems have been adopted. In addition, the tension control technology that has been adapted to it has also made a major breakthrough. It adopts PLC programmable tension controller for complete machine control, touch computer screen man-machine interface operation, high degree of automation, easy operation, all-round parameter setting, operability, high stability and durability. Therefore, modern gravure printing machines have greatly improved the quality of printed matter.

Regarding the tension control of the intaglio, it is first necessary to understand what tension control is. At present, there are two main parts of the gravure printing machine that need to be applied to the tension control principle: the first part is from the feeding to the feeding traction roller. Overprinting error, that is, the overprinting accuracy between the colors of multicolor printing is poor. If the positional relationship of the printing press mechanism is correct, the error is caused by the elongation or shortening of the material, and a certain amount of elongation is controlled within the allowable range, and the tension control is most effective. The second part is from the receiving traction roller to the post-receipt parts. Attention should be paid to the tension control of the receiving coil to be tight, tidy and reliable.

The tension controller system of the gravure press is essentially a special follower system in which the input amount changes according to an adjustable attenuation law. The control of tension can be said to be the core of the whole machine control. As long as the tension control is stable and the tension change is small, the color registration accuracy and the reject rate of the gravure printing machine are easily controlled. Therefore, in order to ensure gravure quality and efficiency, a fully functional tension controller system must be provided. However, in the printing process, the factors that cause the fluctuation and change of the gravure machine tension are often complicated. The main influencing factors are as follows: the gravure printing machine roll is in the process of receiving and unwinding, winding and releasing. The diameter of the roll is constantly changing and the change in diameter must cause a change in the tension of the strip. When the unwinding torque is constant, the diameter is reduced and the tension is increased. The winding is reversed. If the winding torque is constant, the tension will decrease as the winding diameter increases. This is determined by the inherent characteristics of the gravure press and is one of the main factors that cause the change in the tension of the tape; the material is not uniform in the material. Such as the fluctuation of the elastic modulus of the material, the thickness of the material varies along the width and length, the eccentricity of the material roll, and the temperature and humidity changes in the production environment will have a subtle effect on the tension fluctuation of the tension controller; During the automatic refueling process without stopping the machine, the material receiving and breaking of the material will cause the sudden tension of the original machine to suddenly change. The higher the speed of the equipment, the greater the interference. At this time, the tension controller system should be able to quickly and randomly adjust according to the tension of the belt tension to restore the tension to the original stable state in time. There are deviations in the manufacturing precision and assembly accuracy of the main components of the gravure printing machine such as the base, the wall panel, and the guide roller. For example, the flatness and straightness of the base assembly, the verticality of the assembly of the wall panel and the base, the level of assembly of the various rollers and guide rollers, and the parallelism between them, their respective runout deviations, mass dynamic balance deviations, etc. Etc., all requirements are very strict. Otherwise, the tension on the strip will change slightly as the strip runs on the plate roll and the many guide rolls. Eventually it will be reflected on the entire machine, resulting in irregular changes in tension. In addition, the gears and reduction gearboxes in the main drive system of the gravure printing machine should be equipped with no gap precision transmission to ensure the synchronous operation of the plate rollers of each printing unit. If the transmission synchronization error is caused during the printing process, the tension of each printing unit will be inevitable. Make a difference.

The main types and characteristics of tension controllers. Tension control refers to the ability to permanently control the tension of the tape as it is transported over the device. This control must be effective for any speed of the machine, including acceleration, deceleration and constant speed of the machine. Even in the case of an emergency stop, it has the ability to ensure that the tape does not break. The gravure press tension control is basically divided into three categories: manual tension control, open-loop semi-automatic tension control and closed-loop 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. However, the modern gravure press manual tension control system has been basically eliminated, and only exists as a mode of operation in the closed-loop automatic tension control system. Open-loop semi-automatic tension control, also known as roll-diameter tension control, uses a proximity switch mounted on the reel to detect the rotational speed of the reel and is calculated by cumulative calculation of the initial diameter of the reel diameter and material thickness. The current diameter of the winding or unwinding drum, the corresponding change in the winding diameter, outputs a control signal to control the winding torque or the unwinding braking torque, thereby adjusting the tension of the belt. Because each revolution of the reel, the winding diameter will occur twice as much as the thickness of the strip. This tension control is not affected by external stimuli and can perform stable tension control. However, due to factors such as torque variation, linear variation, and mechanical loss of the transmission, the absolute accuracy of such tension control is poor. The closed-loop 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 this signal with the preset tension value of the controller, the control is calculated. The signal, the automatic control execution unit makes the actual tension value equal to the preset tension value for the purpose of tension stabilization. It is currently a more advanced method of tension control. In addition, in the medium and high-grade printing press tension controller system manufactured and sold in China, the higher printing speed and production process put forward higher requirements for tension control, making the magnetic powder clutch unable to perform the execution unit of such system. . Therefore, it has been replaced by AC and DC servo motor execution units in modern gravure printing machines, high-speed slitting machines and high-speed coating laminating machines, achieving more advanced tension servo control.

Application of tension controller: floating roller tension servo control system. The floating roller type tension servo numerical control device system adopts a four-stage closed-loop automatic tension servo control system. The four-stage tension refers to the four parts of unwinding tension, feed traction tension, discharge tension and winding tension. The four-stage tension control is controlled by the tension controller of each section, and the feedback of the floating roller displacement detecting device constitutes a closed loop for automatic control. The difference is that the unwinding and winding unit uses an AC vector variable frequency motor, while the feed traction and discharge traction unit uses a servo motor. On the one hand, since the unwinding and winding unit adopts the AC vector variable frequency motor, the control speed range is wide and the precision is high. Whether it is good performance at low speed or high speed, as long as the closed loop control vector frequency conversion motor can be stabilized. Unwinding tension and winding tension. On the other hand, the traction traction and discharge traction unit selects the servo motor because the traction tension controller forms a closed loop through the feedback of the floating roller displacement detecting device, and controls the servo motor to obtain a stable tension according to the host setting line speed. Because of this, it must be linked with the host, coordinated by the central control cabinet for centralized control and operation; touch screen tension CNC system. The touch screen tension numerical control device adopts a full-closed automatic tension controller system with four sections of unified control mode. The machine is controlled by PLC programmable controller. The man-machine interface adopts HITECH touch screen for operation parameter setting and display. The unwinding, feeding traction, discharge traction and winding are coordinated and centralized by the main control cabinet. The four-stage tension refers to the four-part tension such as unwinding tension, feed traction tension, discharge tension, and winding tension. All four tensions are automatically controlled by an AC vector variable frequency motor. The HITECH touch screen is installed on the operation panel of the receiving unit, which can set the parameters such as speed, tension and coil diameter, and also display the parameters such as speed and tension in real time. The system has high control precision, fast response and good stability. The operator can start, accelerate, decelerate or stop the operation from any part of the machine, which is very convenient. In addition to the tension control operation panel, the discharge and receiving wall panels are equipped with the entire machine start, stop and emergency stop switches. Due to the AC vector frequency conversion motor receiving, the control speed range is wide, and it has good performance at both low speed and high speed, and can realize taper tension control and excellent winding effect. In addition, it also includes high-speed non-stop automatic feeding and cutting, receiving and unwinding pre-drive, safe automatic alarm and length automatic counting and display control functions. The maximum control tension is 20kg, and the host printing speed is 0~200m/min.

In addition, the system also has the functions of high-speed operation, non-stop switching volume, pre-loading and unwinding, safe automatic alarm and automatic length counting and display control. The system not only has high control precision, fast response, small tension fluctuation, but also can be used as an accumulator to absorb the sudden peak of tension in the system. And it is easy to achieve high-speed switching volume, which has a good buffer absorption effect when the machine is added or decelerated. The maximum control tension is 25kg, and the host printing speed is 0~250m/min.

At present, although China's gravure printing equipment manufacturing industry has made great progress, in general, the printing machine industry has not applied a wide range of advanced tension controller devices. With the deepening of WTO accession and the development of the industry, various printing machinery, Packaging machinery will use more tension control methods to improve product quality.