Film surface rolling pressure control method

Abstract

A film surface winding pressure control method comprises the following steps that in the winding process, a film roll makes contact with and presses the surface of a friction roller; continuously monitoring the diameter D of the film roll and the length of the rolled film; after a film roll diameter value D0 is monitored, a corresponding rolling pressure target value F0 is determined according to the function relation between the film roll diameter and the rolling pressure target value, the net weight G1 of the film roll is measured and calculated according to the length of the rolled film, the net weight G1 of the film roll is added with the weight G2 of a rolling shaft, the weight G3 of a paper core cylinder and the weight G4 of a secondary support, and then the film roll diameter value D0 is obtained; the total ballast weight G is obtained, namely G = G1 + G < 2 + > G < 3 + > G4; calculating an ideal inclination angle theta required by the linear guide rail according to a formula theta = arcsin (F0 / G); and the stepping motor drives the first-stage support to rotate, so that the actual inclination angle a of the linear guide rail is equal to the calculated ideal inclination angle theta. According to the device, the actual rolling pressure value can be equal to the set rolling pressure target value, and the rolling pressure can be evenly distributed in the axial direction of the film roll.

Description

Technical Field

[0001] The present invention belongs to the technical field of film winding, and in particular relates to a method for controlling film surface winding pressure. Background Art

[0002] Figure 1 As shown, after the film is produced, it is wound up by a paper core tube 6 sleeved on a winding shaft 3 to form a film roll 8, wherein the winding shaft 3 is generally a hollow inflatable shaft, and the diameter of the paper core tube 6 is generally less than 10 cm, while the diameter of the film roll after winding can reach a maximum of about 100 cm. During the winding process, the speed of the film conveyed upstream of the production line remains basically unchanged, that is, the linear speed of the film roll winding the film remains basically unchanged, which means that the rotation speed of the film roll and the winding shaft at the beginning of winding can reach about 10 times the rotation speed when the winding is nearly completed.

[0003] From the perspective of the film winding power source, the film winding forms mainly include the following two forms: the first is center winding. As the name suggests, the power for the film roll to rotate comes from the winding shaft located in the center of the film roll, and the winding shaft is directly driven by the winding motor; the second is surface winding. As the name suggests, the power for the film roll to rotate comes from the surface friction roller (referred to as friction roller) in contact with the surface of the film roll. The friction roller is directly driven by the friction roller motor, and the friction roller 4 is pressed on the surface of the film roll 8 and rubs the film roll 8. Figure 1 shown.

[0004] In order for the friction roller to effectively rub the film roll, pressure needs to be maintained between the film roll and the surface of the friction roller. This pressure is called winding pressure. Winding pressure is an important quality control indicator of the surface winding process and needs to be controlled. If the winding pressure is too high, it will cause material rupture or surface wear. If it is too low, it will not be conducive to the removal of air involved in the film roll, nor will it be conducive to improving the density of the film roll. During the winding process, as the diameter of the film roll increases, the winding pressure may need to be gradually reduced (called taper pressure in the industry), or it may need to remain unchanged (called constant pressure in the industry), depending on other winding process parameters of the entire production line and the film material, film thickness, etc. Before each winding, the functional relationship curve between the coil diameter D and the winding pressure target value F can be planned and set in advance, so that the winding pressure can be continuously adjusted according to the real-time diameter of the coil during the winding process; of course, if it is a constant pressure method, then the functional relationship curve between the two is a horizontal line.

[0005] During the winding process, both ends of the winding shaft of the film roll are installed on the winding shaft support, and the central axis position of the friction roller is fixed. As the diameter of the film roll continues to increase, the film roll will continue to retreat, so the winding shaft support needs to be installed on a linear guide rail and continue to retreat; on the other hand, in order to maintain a winding pressure between the film roll and the surface of the friction roller, the prior art also provides a cylinder 7 that applies thrust to the winding shaft supports on the left and right sides. The thrust of the cylinder 7 acts on both ends of the winding shaft and is transmitted to the middle of the winding shaft through the two ends of the winding shaft 3 along the axial direction of the winding shaft, and is transmitted to the surface of the friction roller 4 through the film roll 8 by the winding shaft 3. Figure 1 shown.

[0006] However, the existing winding pressure control method has low precision and can only be applied to ordinary film winding processes. In recent years, the film winding width has been developing towards ultra-wide, the film winding speed has been developing towards ultra-high speed, and the film thickness has been developing towards ultra-thin. The above development has made the problem of insufficient precision of the traditional winding pressure control method increasingly obvious, mainly due to the following reasons: 1. The cylinder applies pressure through the two ends of the winding shaft. The winding shaft is a hollow air shaft, not an absolutely rigid body. It will deform after being subjected to force. Therefore, when the above pressure is transferred to the film roll, the winding pressure shows a trend of gradually decreasing from the two ends of the winding shaft to the middle of the winding shaft. For example, Figure 1 In the figure, the winding pressure at point B is less than that at points A\C; for ultra-wide films, the corresponding winding shaft length may reach three or four meters or even longer, making the degree of winding pressure decay from both sides to the middle more obvious, resulting in a high degree of difference in winding pressure at different parts of the film roll axis, which is not conducive to accurate control of winding pressure; Second, in the traditional method, the winding shaft is supported by both ends and is completely suspended in the middle. The diameter of the winding shaft is generally less than ten centimeters. If it is long, for example, three or four meters, it will appear thinner, and the middle section is more likely to sag and deform the winding shaft. Especially at the beginning of the high-speed winding process, the bending deformation of the winding shaft will be aggravated due to the high-speed rotation, which is more unfavorable for accurately controlling the winding pressure and easily affects the winding quality. 3. The pressure of the cylinder comes from the air source in the factory workshop, but the air source in the factory workshop is not only responsible for supplying air to the cylinders at both ends of the take-up shaft, but also needs to supply air to a large number of other equipment in the factory workshop; therefore, if other equipment happens to suddenly use a large amount of air during a certain period, the pressure of the air source will fluctuate and decrease, resulting in a decrease in the pressure of the cylinders at both ends of the take-up shaft. This problem may not have much impact on ordinary films, but for ultra-thin films / films with strong adhesive coatings on the surface / films with delicate coatings on the surface, the impact is greater because of the high requirements for the accuracy of the winding pressure. Summary of the invention

[0007] The purpose of the present invention is to overcome the above-mentioned shortcomings and provide a method for controlling the winding pressure on the film surface, which can not only make the actual value of the winding pressure accurately equal to the set winding pressure target value, but also make the winding pressure evenly distributed along the axial direction of the film roll.

[0008] The purpose can be achieved according to the following scheme: a film surface winding pressure control method, the film surface winding device adopted includes a friction roller and a winding shaft, and winding shaft supports are respectively provided at both ends of the winding shaft, each winding shaft support includes a primary support and a secondary support, the primary support is rotatably mounted on the frame, and the rotation center axis of the primary support overlaps with the center axis of the friction roller; the primary support is provided with a linear guide rail, the secondary support can be slidably mounted on the linear guide rail of the primary support, and the two ends of the winding shaft are respectively placed on the secondary supports on the corresponding sides; when the extension direction of the linear guide rail is horizontal, the vertical position of the center axis of the winding shaft is flush with the vertical position of the center axis of the friction roller; a stepping motor for driving the primary support to rotate is also installed on the frame; the following steps are included: Before winding, establish the functional relationship between the film roll diameter and the winding pressure target value; During the winding process, the film roll on the winding shaft touches the surface of the friction roller; the diameter D of the film roll and the length of the film that has been wound are constantly monitored; Whenever the film roll diameter value D0 is monitored, the corresponding winding pressure target value F0 is determined according to the functional relationship between the film roll diameter and the winding pressure target value, and the net weight G1 of the film roll is calculated according to the length of the wound film. The net weight G1 of the film roll is added to the weight G2 of the winding shaft, the weight G3 of the paper core tube and the weight G4 of the secondary support to obtain the total ballast weight G, that is, G=G1+G2+G3+G4; then the ideal inclination angle θ required for the linear guide is calculated according to the formula θ=arcsin(F0 / G); the stepper motor drives the primary support to rotate so that the actual inclination angle a of the linear guide is equal to the calculated ideal inclination angle θ.

[0009] Preferably, an arc-shaped rack is fixed to the edge of the primary support of the film surface winding device, and a gear is also installed on the frame, the gear is meshed with the arc-shaped rack, and the stepping motor drives the connecting gear.

[0010] The present invention has the following advantages and effects: 1. When the extension direction of the linear guide is horizontal, the vertical position of the central axis of the winding shaft is flush with the vertical position of the central axis of the friction roller. Therefore, the sliding direction of the winding shaft on the linear guide is the radial direction of the friction roller, and its sliding tendency direction on the linear guide is also the radial direction of the friction roller, specifically the centripetal direction of the friction roller; during the winding process, the linear guide of the primary support is in an inclined state, and the gravity of the film roll, the winding shaft, the secondary support and the paper core tube presses on the friction roller along the radial component of the film roll to form a winding pressure, and the magnitude of the winding pressure F is equal to G×sina (a is the actual inclination angle of the linear guide); on the other hand, the actual inclination angle a of the linear guide controlled by the stepper motor is equal to the ideal inclination angle θ, and the ideal inclination angle θ is calculated according to the formula θ=arcsin(F0 / G), so during the winding process, the magnitude of the actual winding pressure F can be accurately equal to the winding pressure target value F0.

[0011] 2. The winding pressure mainly comes from the weight of the film roll and the winding shaft. Therefore, the winding pressure is very evenly distributed along the axial direction of the film roll. The winding pressure in the middle part of the film roll and at both ends of the film roll are basically the same.

[0012] 3. The winding pressure comes from the weight of the film roll, winding shaft, secondary support and paper core tube. Its size is not affected by the fluctuation of air source pressure in the factory workshop, which is conducive to the precise control of the winding pressure.

[0013] 4. In the initial stage of winding, although the winding shaft rotates at a very high speed, the weight of the film roll is very small, so the actual inclination angle a of the linear guide is relatively large, that is, the linear guide has a large inclination, and the winding shaft is located obliquely above the friction roller. Therefore, the friction roller can support part of the weight of the winding shaft and the film roll, reducing the degree of bending deformation of the winding shaft due to suspension and high-speed rotation, and avoiding large bending of the winding shaft due to high-speed rotation in the initial stage of winding, which is conducive to better control of the winding pressure.

[0014] Due to the above four reasons, the winding pressure of the present invention can be evenly distributed along the axial direction of the film roll, and the actual value of the winding pressure can be accurately equal to the set winding pressure target value F0, and the degree of bending and deformation of the winding shaft due to high-speed rotation can be reduced, thereby better controlling the winding pressure and improving the winding quality. It is particularly suitable for the winding process of thin films that require high winding pressure control accuracy, such as the winding process of thin films with large width, high winding speed or high viscosity. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a schematic diagram of the traditional surface winding method.

[0016] Figure 2 It is a schematic diagram of the structure of a film surface winding device used in a specific embodiment of the present invention.

[0017] Figure 3 yes Figure 2 Schematic diagram of the support structure at both ends of the reel.

[0018] Figure 4 yes Figure 2 Schematic diagram of the structure of the middle-level support.

[0019] Figure 5 It is a schematic diagram of the state of a specific embodiment of the present invention when the diameter of the film roll is small.

[0020] Figure 6 yes Figure 5 Schematic diagram of the mechanical principle analysis of the state shown.

[0021] Figure 7 It is a schematic diagram of the state of a specific embodiment of the present invention when the diameter of the film roll is large.

[0022] Figure 8 It is a schematic diagram of a functional relationship curve between the film roll diameter D and the winding pressure target value F according to a specific embodiment of the present invention. DETAILED DESCRIPTION

[0023] A film surface winding pressure control method, the film surface winding device used includes a friction roller 4, a winding shaft 3, and winding shaft supports are respectively provided at both ends of the winding shaft 3. Figure 2 , Figure 3 , Figure 4 As shown, each winding shaft support includes a primary support 1 and a secondary support 2. The primary support 1 can be rotatably mounted on the frame, and the rotation center axis of the primary support 1 overlaps with the center axis of the friction roller 4; the primary support 1 is provided with a linear guide rail 11, and an arc-shaped rack 12 is fixed to the edge of the primary support 1. The secondary support 2 can be slidably mounted on the linear guide rail 11 of the primary support, and the two ends of the winding shaft 3 are respectively placed on the secondary support 2 on the corresponding side; when the extension direction of the linear guide rail 11 is horizontal (such as Figure 2 As shown in the state), the center axis of the reel 3 (in Figure 2 The vertical position of the friction roller 4 (point H) is the same as the central axis of the friction roller 4 (in Figure 2 The vertical position of the film surface is flush with that of point E); a gear and a stepper motor 5 are also installed on the frame, and the stepper motor 5 drives the connecting gear, and the gear and the arc rack 12 are meshed; the film surface winding pressure control method includes the following steps: Before winding, establish the functional relationship curve between the film roll diameter and the winding pressure target value. The functional relationship curve is as follows: Figure 8As shown, the functional relationship curve can be determined according to the production process of the entire production line (including winding speed, winding tension) and the material and thickness of the film, and belongs to the prior art; during the winding process, the film roll 8 on the winding shaft 3 touches the surface of the friction roller 4, and the diameter D of the film roll 8 and the length L of the wound film are continuously monitored; whenever the diameter value D0 of the film roll 8 is monitored, the corresponding winding pressure target value F0 is determined according to the functional relationship between the film roll diameter and the winding pressure target value, and the net weight G1 of the film roll is calculated according to the length L of the wound film (the net weight G1 of the film roll is equal to the weight of the film per unit length multiplied by the length L of the wound film, and the weight of the film per unit length is known), the net weight G1 of the film roll 8 is added to the weight G2 of the winding shaft 3, the weight G3 of the paper core tube and the weight G4 of the secondary support 2, and the total ballast weight G is obtained, that is, G= G1+ G2+ G3+ G4; then the ideal inclination angle θ required by the linear guide 11 is calculated according to the formula θ=arcsin(F0 / G); the stepper motor 5 drives the primary support 1 to rotate through the gear and the arc rack 12, so that the actual inclination angle of the linear guide (such as Figure 6 ∠a shown in the figure) is equal to the calculated ideal inclination angle θ.

[0024] The principle of the above embodiment is explained as follows: During the winding process, the linear guide rail 11 of the primary support is in an inclined state, and the secondary support 2 has a tendency to slide down along the linear guide rail 11. The gravity of the film roll 8, the winding shaft 3, the secondary support 2, and the paper core tube presses on the friction roller 4 along the radial direction of the film roll to form a winding pressure F. The magnitude of the winding pressure is equal to G×sinb, such as Figure 6 As shown, in Figure 6 ∠b=∠a, so the winding pressure F= G×sina. Due to the actual inclination angle ( Figure 6 In the figure, ∠a) is controlled by a stepper motor to be equal to the ideal inclination angle θ, which is calculated according to the formula θ=arcsin(F0 / G), so the actual winding pressure F will be equal to the winding pressure target value F0.

[0025] In the initial stage of winding, the diameter of the film roll 8 is small, the length L of the wound film is short, the net weight G1 of the film roll is small, and the actual inclination angle a is large. Therefore, part of the weight of the winding shaft 3 and the film roll 8 can be carried on the friction roller 4, that is, the winding shaft 3 and the film roll will not be suspended in the air. Figure 5 As shown; as the winding continues, the diameter of the film roll 8 gradually increases, the net weight G1 of the film roll gradually increases, and the stepper motor 5 gradually drives the arc rack 12 of the primary support 1 to rotate clockwise through the gear, so that the primary support 1 and the linear guide 11 rotate synchronously clockwise around the rotation center axis of the primary support 1, and the actual inclination angle a gradually decreases, as shown in FIG. Figure 7 shown.

[0026] The inclination angle of the linear guide 11 refers to the angle between the linear guide 11 and the horizontal line (such as Figure 6 The angle between the straight line m is as follows: Figure 6 In the above winding process, the linear guide 11 rotates synchronously with the primary support 1. During the rotation of the primary support 1, the actual inclination angle a of the linear guide 11 changes continuously, and the change value of the inclination angle of the linear guide 11 is equal to the rotation angle of the primary support 1. Therefore, as long as the rotation amount of the stepper motor 5 is controlled, the rotation angle of the primary support 1 can be controlled, and then the actual inclination angle a of the linear guide 11 can be controlled.

[0027] The film surface winding device structure used in the above embodiment is the same as the structure disclosed in the Chinese invention patent application with application publication number CN114348721A, but the purpose of setting the structure in CN114348721A is only to enable the primary support to rotate during the roll change process after the winding is completed, thereby driving the secondary support to rotate to the bottom of the second linear guide rail so as to receive the spare winding shaft sliding down from the second linear guide rail, and then the primary support rotates in the opposite direction to transfer the spare winding shaft to the winding position, so that the spare winding shaft becomes the main winding shaft, and then the winding begins. In short, in the normal winding process of the structure of CN114348721A, the first linear guide rail is always kept in a horizontal position, and the purpose of setting the rotating support is only for the convenience of roll change. Therefore, the technical purpose, technical features, and technical effects of the winding method disclosed in CN114348721A are different from those of the present application.

Claims

1. A film surface winding pressure control method, the film surface winding device used includes a friction roller and a winding shaft, and winding shaft supports are respectively provided at both ends of the winding shaft, each winding shaft support includes a primary support and a secondary support, the primary support is rotatably mounted on a frame, and the rotation center axis of the primary support overlaps with the center axis of the friction roller; the primary support is provided with a linear guide rail, the secondary support can be slidably mounted on the linear guide rail of the primary support, and the two ends of the winding shaft are respectively placed on the secondary supports on the corresponding sides; when the extension direction of the linear guide rail is horizontal, the vertical position of the center axis of the winding shaft is flush with the vertical position of the center axis of the friction roller; a stepping motor for driving the primary support to rotate is also installed on the frame; the steps include: Before winding, establish the functional relationship between the film roll diameter and the winding pressure target value; During the winding process, the film roll on the winding shaft touches the surface of the friction roller; the diameter D of the film roll and the length of the film that has been wound are constantly monitored; Whenever the film roll diameter value D0 is monitored, the corresponding winding pressure target value F0 is determined according to the functional relationship between the film roll diameter and the winding pressure target value, and the net weight G1 of the film roll is calculated according to the length of the wound film. The net weight G1 of the film roll is added to the weight G2 of the winding shaft, the weight G3 of the paper core tube and the weight G4 of the secondary support to obtain the total ballast weight G, that is, G= G1+G2+ G3+ G4; then the ideal inclination angle θ required for the linear guide is calculated according to the formula θ=arcsin(F0 / G); the stepper motor drives the primary support to rotate so that the actual inclination angle a of the linear guide is equal to the calculated ideal inclination angle θ.

2. A method for controlling film surface winding pressure according to claim 1, characterized in that: The edge of the primary support of the film surface winding device is fixed with an arc-shaped rack, and a gear is also installed on the frame. The gear meshes with the arc-shaped rack, and the stepping motor drives the connecting gear.

Images