Application of floating roller in tension control of winding and unwinding of printing machine (Part 2)
precautions for installation of floating roller floating roller plays a role in detecting tension changes in the process of automatic tension control. At the same time, the floating roller can absorb or slow down; The influence of medium tension jump on the stability of the system. The correct installation and use of the floating roll has a great relationship with the response sensitivity of the whole control system. The following are some links that need to be paid attention to in the installation of the floating roll system and the universal experimental machine used for static testing.
(1) the tension roll only bears one-way pressure in the working state, the cylinder can be connected with compressed gas on one side, and the air outlet can be directly connected to the atmosphere. In this way, only the pressure of the air inlet needs to be controlled. A throttle valve is installed at the air outlet of the cylinder, which can control the exhaust speed, so that the cylinder has a back pressure, which can prevent the front of the cylinder; Medium speed is too fast to produce impact. When in use, the flow valve should be adjusted to the appropriate position, taking into account the sensitivity of tension detection. The pneumatic principle of the floating roller is shown in Figure 3
(2) the cylinder adopts a low friction cylinder, which can reduce the friction between the piston and the cylinder block and improve the reaction sensitivity of the cylinder. When the tension acting on the floating roller fluctuates slightly, it can also fluctuate and cause potential crime to react
(3) the pressure regulating valve must be a precision pressure regulating valve. The precision pressure regulating valve has high pressure stabilization accuracy, which can reduce the fluctuation of gas pressure at the inlet and cause the swing roll to jump, resulting in the change of tension. At the same time, when the tension of the film coil increases, the counterclockwise direction fully absorbs the leading industries and characteristic industries in advanced regions. When the torque of the supporting policy direction is greater than the clockwise direction, the cylinder moves upward. The gas between the air inlet of the cylinder and the pressure regulating valve is compressed. Pressure increases. The precise pressure regulating valve quickly discharges the gas through the exhaust port, so that the gas pressure in the cylinder remains unchanged. When taper control is needed, the precision pressure regulating valve is often changed to E/P change-over valve to change the change of knife opening in the winding process by controlling the different pressure of the cylinder
(4) the film roll should have a large enough wrap angle on the floating roll. As shown in Figure 4, the wrap angle of the film on the roll is., Tension on the film and effective resultant force F on the roll α= FCOS α 1，+FCOS α 2: And α 1, ten α 2=π- α。 If α The smaller, α 1 and α The greater the sum of 2, then f α It will also become smaller and larger tension changes are necessary to cause the swing of the floating roller, which reduces the sensitivity of the floating roller to the tension changes.
(5) the mechanical limit is installed within the swing range of the floating roller; Medium device. It can slow down at the end of the stroke of the cylinder; The operators in strictly follow the operating procedures to avoid the piston hitting the cylinder block at the end of the stroke, which can prolong the service life of the cylinder
(s) the potentiometer adopts 360 rotation and conductive potentiometer. Its effective swing angle is 330 °, and the rotation angle should be less than 330 "in design, with a little margin left. In order to avoid entering the dead zone and affecting the control when the swing amplitude is large. At the same time, the gear? The transmission clearance should be as small as possible to ensure the last measurement accuracy
the control scheme of indirect tension detection with floating roller has the advantages of simple control, convenient adjustment and stable operation. It is often used in the occasions where automatic tension control of winding and unwinding is required in printing machines and other machinery
Author: Weng Chongxi Guangdong Shantou Jinlan Packaging Machinery Co., Ltd.
source: printing technology 2005, 10 (packaging and decoration printing)
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