Low-tension control device for plastic film

Abstract

A plastic film low tension control device comprises a swing rod and a floating guide roller, and fixed guide rollers are arranged on the upstream and the downstream of the floating guide roller respectively. A piston rod of the proportional valve cylinder applies upward acting force to the swing rod, and the piston rod of the proportional valve cylinder is fixedly connected with a linear displacement detector for measuring displacement; the upper limiting block and the lower limiting block are used for limiting the swing amplitude of the swing rod; the proportional valve air cylinder and the floating guide roller are located on the same side of the swing rod swing shaft. A balancing weight is further installed at the tail end of the swing rod, the balancing weight and the proportional valve air cylinder are located on the two opposite sides of a swing shaft of the swing rod respectively, and the torque generated by the balancing weight is just equal to the torque generated by the floating guide roller. The tension of the thin film can be more accurately regulated and controlled, and the thin film can be more effectively prevented from being strained.

Description

Technical Field

[0001] The utility model belongs to the technical field of plastic film processing and production equipment, and particularly relates to a plastic film low tension control device. Background Art

[0002] Some films for special purposes are extremely thin, or their materials are prone to plastic deformation and can withstand very low tension. Therefore, low tension is required during winding. During the low-tension winding process, the winding tension will also fluctuate. If the winding tension fluctuates in a direction that is too large, the film may be damaged. In order to solve this problem, the existing technology adopts technical solutions such as Figure 1 As shown, it includes a floating guide roller 11 and two floating guide rollers (fixed guide roller 21 and fixed guide roller 22) that can float up and down. The floating guide roller 11 is installed on the rocker 3 and uses the piston rod 40 of the proportional valve cylinder 4 to push up the rocker 3. It is also provided with an upper limit block 61 and a lower limit block 62 to limit the swing amplitude of the rocker 3. The piston rod of the proportional valve cylinder 4 is fixedly connected to a linear displacement detector 5 for measuring displacement. Figure 1 As shown. Under normal working conditions, the piston rod 40 of the proportional valve cylinder is at the midpoint of its stroke; when the film winding tension fluctuates in a direction that is too large, the piston rod 40 of the proportional valve cylinder can be retracted downward, and the floating guide roller 11 can be moved downward, shortening the film path of the film 8, as shown. Figure 2 As shown, this prevents film damage. During this process, the linear displacement detector 5 detects the displacement of the piston rod 40 of the proportional valve cylinder and notifies the central control system, which then commands the production line to restore tension, reducing it until the piston rod 40 of the proportional valve cylinder returns to the midpoint of its stroke. In the above structure, the piston rod 40 of the proportional valve cylinder exerts a clockwise torque on the rocker arm 3, while the weight of the floating guide roller 11 exerts a counterclockwise torque on the rocker arm 3. The difference between the clockwise and counterclockwise torques is sufficient to counteract the tension torque of the film 8.

[0003] However, the above structure still has the following aspects to be improved:

[0004] 1. During the up and down swinging of the rocker 3, the distance between the floating guide roller 11 and the rocker shaft 30 (equivalent to the force arm of the floating guide roller weight G) will change, for example Figure 1 The middle moment arm AB is greater than Figure 2 The middle arm AH, therefore, the difference between the clockwise moment (the torque generated by the piston rod 40 of the proportional valve cylinder on the rocker arm 3) and the counterclockwise moment (the torque generated by the weight of the floating guide roller 11 on the rocker arm 3) will also change, thereby affecting the precise control of the tension;

[0005] Second, when the tension of the film 8 changes, the swing and reaction of the pendulum 3 are not sensitive enough, and the amplitude of the change of the film path length of the film 8 (i.e. Figure 1 、 Figure 2 The length value of CD+EF-KL-MN) is not large. Thus, when the rocker arm 3 contacts the lower limit block 62, if the film tension control of the production line has not yet completed the tension repair due to a delayed reaction, the rocker arm 3 can no longer continue to swing counterclockwise, and the film 8 will be hard-wound. Utility Model Content

[0006] The purpose of the utility model is to overcome the above-mentioned shortcomings and provide a low-tension control device for plastic film, which can more accurately regulate the tension of the film and more effectively avoid damaging the film.

[0007] Its purpose can be achieved according to the following scheme: a low-tension control device for plastic film, including a rocker arm and a floating guide roller, with fixed guide rollers provided upstream and downstream of the floating guide roller respectively; a proportional valve cylinder is also provided, the piston rod of the proportional valve cylinder applies an upward force to the rocker arm, and the piston rod of the proportional valve cylinder is fixedly connected to a linear displacement detector for measuring displacement; an upper limit block and a lower limit block are also provided to limit the swing amplitude of the rocker arm; the proportional valve cylinder and the floating guide roller are located on the same side of the rocker arm's swing axis; it is characterized in that a counterweight block is also installed at the end of the rocker arm, the counterweight block and the proportional valve cylinder are located on opposite sides of the rocker arm's swing axis respectively, and the torque generated by the counterweight block is exactly equal to the torque generated by the floating guide roller.

[0008] There are two floating guide rollers, which are installed on the same side of the rocker arm shaft. There are three fixed guide rollers, which are located below the two floating guide rollers. The three fixed guide rollers are arranged in a horizontal row, and the horizontal positions of the fixed guide rollers and the movable guide rollers form a cross arrangement.

[0009] The utility model has the following advantages and effects:

[0010] 1. When the utility model is working, the torque generated by the counterweight is exactly equal to the torque generated by the floating guide roller, that is, the torques of the two are exactly offset. Therefore, no matter what angle the rocker arm swings to, the difference between the clockwise torque and the counterclockwise torque will not be affected by the change in the force arm of the floating guide roller. The difference between the clockwise torque and the counterclockwise torque remains unchanged (always equal to the torque generated by the proportional valve cylinder), which is conducive to the precise control of the tension.

[0011] 2. Compared with the traditional technical solution of "one floating guide roller and two fixed guide rollers", the technical solution of "two floating guide rollers and three fixed guide rollers" has the following advantages:

[0012] 1. Both technical solutions share a common feature: during the swing arm's swing due to tension fluctuations, the floating guide roller can continue to float downward as long as the arm has not yet contacted the lower limit block. As long as the floating guide roller can continue to float downward, the film will generally not be damaged by hard tension. In the present invention, however, the range of variation in the film path length is doubled. Therefore, when tension fluctuations disrupt the balance of the swing arm, the time it takes for the arm to contact the lower limit block is doubled. This means that the entire production line has twice the time to repair tension fluctuations, providing more time for tension repair, as long as tension repair is completed before the swing arm contacts the lower limit block.

[0013] 2. In the traditional technical solution of "single floating guide roller and two fixed guide rollers", assuming the film tension is F, the downward pulling force on the film borne by the rocker arm is 2F. Therefore, when the film tension fluctuates, the change in the pulling force on the rocker arm will be magnified by two times; in the technical solution of "two floating guide rollers and three fixed guide rollers", the downward pulling force on the film borne by the rocker arm is 4F. Therefore, when the film tension fluctuates, the change in the pulling force on the rocker arm is magnified by four times. This means that the rocker arm's sensing will be more sensitive, which is conducive to the central control system of the production line to perceive tension changes more promptly, thereby adjusting the tension earlier and more accurately. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 This is a schematic diagram of the overall structure and normal operating status of a traditional plastic film low tension control device.

[0015] Figure 2 yes Figure 1 Schematic diagram of the adjustment state of the structure shown.

[0016] Figure 3 It is a schematic diagram of the overall structure and normal use state of a specific embodiment of the utility model.

[0017] Figure 4 It is an application Figure 3 Schematic diagram of a plastic film production line according to a specific embodiment is shown.

[0018] Figure 5 yes Figure 3 Schematic diagram of the adjustment state of the specific embodiment shown. DETAILED DESCRIPTION

[0019] Figure 3The low tension control device of a plastic film shown in the figure includes a rocker arm 3 and two floating guide rollers (a floating guide roller 11 and a floating guide roller 12). The floating guide roller 11 and the floating guide roller 12 are installed on the same side of the rocker shaft 30 of the rocker arm. A fixed guide roller 21 is installed upstream of the floating guide roller 11, and a fixed guide roller 22 is installed downstream of the floating guide roller 11. The fixed guide roller 22 is located upstream of the floating guide roller 12, and a fixed guide roller 23 is installed downstream of the floating guide roller 12. The three fixed guide rollers are located below the two floating guide rollers. The fixed guide rollers 21, 22, and 23 are arranged in a horizontal row. The lateral positions of the fixed guide rollers and the movable guide rollers form a cross arrangement. Specifically, the lateral position of the floating guide roller 11 is located horizontally between the fixed guide roller 21 and the fixed guide roller 22. Toward the middle of the position, the lateral position of the floating guide roller 12 is located in the middle of the lateral positions of the fixed guide roller 22 and the fixed guide roller 23; a proportional valve cylinder 4 is also provided, and the piston rod 40 of the proportional valve cylinder 4 applies an upward force to the rocker arm 3. The piston rod 40 of the proportional valve cylinder is fixedly connected to a linear displacement detector 5 for measuring displacement, and an upper limit block 61 and a lower limit block 62 for limiting the swing amplitude of the rocker arm 3 are also provided; the proportional valve cylinder 4 and the two floating guide rollers are located on the same side of the rocker arm shaft 30; a counterweight block 7 is also installed at the end of the rocker arm 3, and the counterweight block 7 and the proportional valve cylinder 4 are respectively located on opposite sides of the rocker arm shaft 30, and the torque generated by the counterweight block 7 is just equal to the torque generated by the two floating guide rollers (with the rocker arm shaft 30 as the fulcrum).

[0020] The operating principle of the above embodiment is as follows:

[0021] This embodiment can be applied to a plastic film production line, which is provided with a reel 9. The film 8 is wound around the fixed guide roller 21, the floating guide roller 11, the fixed guide roller 22, the floating guide roller 12, the fixed guide roller 23 in sequence, and finally wound by the reel 9. Figure 4 shown.

[0022] Under normal working conditions, the tension of the film 8 is maintained at a set normal value, and the piston rod 40 of the proportional valve cylinder 4 is at the midpoint of its stroke, such as Figure 3 As shown; when the winding tension fluctuates in a direction that is too large, the piston rod 40 of the proportional valve cylinder can be retracted downward, the rocker arm 3 rotates counterclockwise, and the two floating guide rollers (floating guide roller 11 and floating guide roller 12) can swing downward to shorten the film path 8, thereby achieving the effect of avoiding damage to the film 8, as shown Figure 5 As shown, at the same time, the linear displacement detector 5 transmits the displacement information of the piston rod 40 to the central control system of the production line. The central control system then orders the production line to repair the tension. The rotation speed of the winding shaft 9 of the production line is slowed down, so that the tension of the film 8 decreases. Before the rocker arm 3 touches the upper limit block 61, the tension repair process is completed, and the tension of the film 8 returns to normal value. Thereafter, the piston rod 40 of the proportional valve cylinder 4 returns to the midpoint of its stroke.

Claims

1. A plastic film low-tension control device, comprising a rocker arm and a floating guide roller, with fixed guide rollers disposed upstream and downstream of the floating guide roller, respectively; a proportional valve cylinder, the piston rod of which applies an upward force to the rocker arm, the piston rod of which is fixedly connected to a linear displacement detector for measuring displacement; upper and lower limit blocks for limiting the swing amplitude of the rocker arm; the proportional valve cylinder and the floating guide roller are located on the same side of the rocker arm's swing axis; and characterized in that: A counterweight is also installed at the end of the rocker arm. The counterweight and the proportional valve cylinder are located on opposite sides of the rocker arm's rocking axis, and the torque generated by the counterweight is exactly equal to the torque generated by the floating guide roller.

2. The plastic film low tension control device according to claim 1, characterized in that: There are two floating guide rollers, which are installed on the same side of the rocker arm shaft. There are three fixed guide rollers, which are located below the two floating guide rollers. The three fixed guide rollers are arranged in a horizontal row, and the horizontal positions of the fixed guide rollers and the movable guide rollers form a cross arrangement.

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