Film rolling brake device

Abstract

The utility model discloses a film rolling brake device, and relates to the technical field of packaging mechanical equipment. On the basis of an existing film rolling brake device, the transmission structure between the tension swing arm and the brake swing arm is provided with the transmission clearance, the transmission clearance means that the tension swing arm swings by a set angle and then drives the brake swing arm to swing, that is, when film drawing is started, force capable of overcoming the gravity of the tension swing arm only needs to be applied firstly, and then the tension swing arm is driven to swing by the brake swing arm. After the tension swing arm is driven to swing upwards by a set angle, when the tension swing arm continues to swing upwards, the swing force of the tension swing arm can be conducted to the brake swing arm, and therefore a brake band on the brake swing arm is made to leave a brake disc, a supporting film roller is released, and a film is smoothly released. According to the utility model, through the arrangement of the transmission clearance, the instantaneous tension when the roll film conveying is started is reduced, and the tension is divided into at least two stages, that is, the tension on the packaging film is increased step by step, so that the probability that the packaging film is stretched and deformed when the packaging film is started to be conveyed is reduced.

Description

Technical Field

[0001] The utility model relates to the technical field of packaging machinery and equipment, and more specifically to a film rolling brake device. Background Art

[0002] In packaging production, a film releasing mechanism is often used to release packaging film. The film releasing mechanism mainly includes a supporting film roller for supporting the film roll, a number of film guide rollers and a film pulling mechanism. The film roll is supported on the supporting film roller. The packaging film released from the film roll is input to the packaging station through the film guide roller and the film pulling mechanism to wrap the material. When the film pulling mechanism repeatedly starts and stops to pull the film, due to inertia or the film roll rotates a certain angle more, more packaging film is released, which is not conducive to the control of the tension of the packaging film and will also affect the packaging effect.

[0003] In the existing packaging equipment, in order to solve this problem, a brake disc is arranged on the supporting film roller, a brake swing arm is installed on the frame, a brake band adapted to the brake disc is installed on the brake swing arm, and a tension swing arm for feedback of the packaging film conveying tension is arranged on the frame of the film placing mechanism. The packaging film released from the film roll is input to the packaging station after passing through a number of film guide rollers and the guide rollers on the tension swing arm and the film pulling mechanism. The tension swing arm is connected to the brake swing arm by transmission. When the tension of the packaging film output becomes low, the tension swing arm is swung downward by its own gravity to ensure the tension of the packaging film conveying. At the same time, the swing of the tension swing arm will drive the brake swing arm to swing. The brake swing arm drives the brake band to approach the brake disc, generating friction force to prevent the supporting film roller from rotating, thereby stopping the supporting film roller and stopping the film roll from releasing the packaging film.

[0004] The above-mentioned brake structure which feeds back the conveying tension of the packaging film through the tension swing arm to adjust the braking force is widely used in the film placing mechanism.

[0005] In actual use, it is found that the above-mentioned brake structure that adjusts the braking force by feeding back the tension of the packaging film through the tension swing arm still has some problems. When the machine is restarted (the packaging film stops being transported) after stopping (the packaging film is pulled again), the force applied by the film pulling mechanism to the packaging film needs to be able to overcome the gravity of the tension swing arm itself so that it can swing upward, thereby driving the brake swing arm to move and prompting the brake band to release the brake disc. It is also necessary to overcome the friction force applied by the brake band to the brake disc, that is, the instantaneous pulling force when starting the film pulling must be greater than the friction force of the brake disc and the gravity of the tension swing arm itself, so that the packaging film can be released smoothly. This results in an increase in the instantaneous pulling force applied by the film pulling mechanism to the packaging film when starting the film pulling, especially for packaging films that are easily stretched and deformed. This frequent start and stop will cause the packaging film to be stretched and deformed, damage the packaging film, and make the packaging film unusable, resulting in waste of packaging film and affecting packaging efficiency. Utility Model Content

[0006] In order to overcome the defects and deficiencies in the above-mentioned prior art, the utility model provides a film roll brake device. The film roll brake device of the utility model is an improvement on the existing film roll brake device. The invention purpose of the utility model is to solve the problem that the instantaneous pulling force applied to the packaging film by the existing film roll brake device when starting is large, which is easy to cause the stretching deformation of the packaging film. On the basis of the existing film roll brake device, the utility model is provided with a transmission virtual position on the transmission structure between the tension swing arm and the brake swing arm. The transmission virtual position means that after the tension swing arm swings to a set angle, it drives the brake swing arm to swing, that is, when starting the film pulling, it only needs to apply a force that can overcome the tension swing arm's own gravity, so that after the tension swing arm is driven to swing upward to a set angle, when the tension swing arm continues to swing upward, its swinging force will be transmitted to the brake swing arm, thereby prompting the brake belt on the brake swing arm to leave the brake disc, release the supporting film roller, and smoothly release the film. The utility model reduces the instantaneous pulling force when starting the roll film conveying by setting the transmission virtual position, and divides the pulling force into at least two stages, that is, gradually increasing the pulling force on the packaging film, thereby reducing the probability of the packaging film being stretched and deformed when starting the conveying.

[0007] In order to solve the above problems existing in the prior art, the utility model is implemented through the following technical solutions.

[0008] The utility model provides a film roll brake device, which includes a supporting film roller, a brake swing arm and a tension swing arm, the supporting film roller is equipped with a brake disc, the brake swing arm is equipped with a brake belt matched with the brake disc, the tension swing arm is transmission-connected with the brake swing arm, and a transmission virtual position is arranged on the transmission structure between the tension swing arm and the brake swing arm, and the setting of the transmission virtual position enables the tension swing arm to swing to a set angle first and then drive the brake swing arm to move.

[0009] Further preferably, the tension swing arm and the brake swing arm are connected via a transmission connecting rod, and the transmission virtual position is arranged on the transmission connecting rod.

[0010] Further preferably, the tension swing arm swings around the tension swing shaft, and a transmission swing rod is coaxially mounted on the tension swing shaft, and the transmission swing rod is connected to the brake swing arm through a transmission connecting rod; the transmission virtual position is arranged on the transmission connecting rod.

[0011] Further preferably, the transmission connecting rod includes a fixed connection joint and a floating connection joint, the floating connection joint is connected to the fixed connection joint, and the floating connection joint is telescoped and displaced relative to the fixed connection joint along the axis of the transmission connecting rod, and the displacement of the floating connection joint relative to the fixed connection joint forms the transmission virtual position.

[0012] More preferably, the floating connection joint and the fixed connection joint are inserted together. A limiting groove is provided on the fixed connection joint, and a limiting member for cooperating with the limiting groove is provided on the floating connection joint. The displacement of the limiting member on the floating connection joint in the limiting groove forms the transmission virtual position.

[0013] More preferably, the tension swing arm swings around the tension swing axis. A transmission swing rod is coaxially assembled on the tension swing axis, and the transmission swing rod is connected to the brake swing arm; the transmission virtual position is arranged on the tension swing axis for transmission between the tension swing arm and the transmission swing rod.

[0014] More preferably, the tension swing axis is fixedly connected to the end of the tension swing arm. A wedge-shaped protrusion is provided at the end of the tension swing axis for assembling the transmission swing rod. A wedge-shaped slot is provided in the mounting hole of the transmission swing rod for assembling the tension swing axis. The wedge-shaped protrusion is correspondingly arranged in the wedge-shaped slot, and the radian of the wedge-shaped protrusion is smaller than the radian of the wedge-shaped slot. The wedge-shaped protrusion rotates by a set angle in the wedge-shaped slot, driving the transmission swing rod to rotate. The displacement of the wedge-shaped protrusion in the wedge-shaped slot is the transmission virtual position.

[0015] More preferably, a tension spring is connected to the brake swing arm. One end of the tension spring is connected to the swing end of the brake swing arm, and the other end is connected to the frame of the film winding brake device.

[0016] More preferably, the other end of the tension spring is connected to the frame of the film winding brake device through a tension adjusting assembly.

[0017] More preferably, the tension adjusting assembly includes a fixed nut fixed on the frame of the film winding brake device, an adjusting bolt threadedly engaged with the fixed nut, and a hanging ring adapted to the hook of the tension spring provided at the end of the adjusting bolt.

[0018] Compared with the prior art, the beneficial technical effects brought by the present utility model are as follows:

[0019] 1. The transmission structure between the tension swing arm and the brake swing arm of the present utility model is provided with a transmission virtual position. The setting of this transmission virtual position makes the swing feedback to the brake swing arm lag, and there is a flexible reaction relying on the self-weight of the tension swing arm. When the equipment starts to operate (when starting to pull the film), the braking force on the film roll is relatively large. With the intervention of the transmission virtual position, the initial tension on the packaging film only needs to overcome the self-weight of the tension swing arm and can be easily started within the stroke range of the transmission virtual position. For the packaging film, it can avoid being stretched and deformed due to excessive initial tension. When the equipment is operating normally, after the swing of the tension swing arm finishes the stroke of the transmission virtual position, the continuous swing of the tension swing arm will drive the brake swing arm to swing, thereby changing the braking force of the brake band on the brake disc on the brake swing arm, and then adjusting the braking force to a level suitable for the film roll tension, ultimately achieving a balancing device. When the equipment stops operating, when the film roll is relatively large, it usually loosens a lot under the action of inertia during shutdown, releasing a part of the packaging film. At this time, the braking force has returned to the maximum state. With the intervention of this transmission virtual position, the tension swing arm can continue to swing with a certain stroke under its own weight (after the braking force reaches the maximum, the tension swing arm can continue to swing along the transmission virtual position), which can keep the packaging film in a tension balance state and avoid problems such as unstable color mark induction and excessive length deviation of the packaging bag due to the film roll being too loose during the next start-up.

[0020] 2. In the present utility model, setting this transmission virtual position in the transmission structure between the tension swing arm and the brake swing arm can achieve the functions of this application. The transmission virtual position is set on the transmission connecting rod, with a more simplified structure and easier implementation, and less modification to the existing film roll braking device. Only by replacing the original transmission connecting rod with a transmission connecting rod with a transmission virtual position can it be achieved.

[0021] 3. In the present utility model, a tension spring is provided on the brake swing arm. Through the setting of the tension spring, when the equipment stops operating and there is no support from the tension swing arm, the tension spring can pull the brake swing arm to quickly restore the braking force. Under the action of the transmission virtual position, the tension swing arm can continue to swing with a certain stroke under its own weight, which can keep the packaging film in a tension balance state and avoid problems such as unstable color mark induction and excessive length deviation of the packaging bag due to the film roll being too loose during the next start-up. At the same time, the setting of the tension spring can also adjust the tension according to the wear condition of the brake band, so that the braking force can be adjusted and adapted to follow the wear of the brake band, and the braking force is adjusted to a level suitable for the film roll tension. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 is a schematic structural diagram of the film roll braking device;

[0023] Figure 2 is Figure 1 a three-dimensional structural diagram of

[0024] Figure 3 Schematic diagram of the transmission structure of the roll film braking device Figure 1 ;

[0025] Figure 4 Schematic diagram of the transmission structure of the roll film braking device Figure 2 ;

[0026] Figure 5 Schematic diagram of the structure of the present utility model with the transmission virtual position arranged on the transmission connecting rod;

[0027] Figure 6 Schematic diagram of the structure of the transmission connecting rod;

[0028] Figure 7 Schematic diagram of the structure with a transmission virtual position arranged between the tension swing shaft and the transmission swing rod Figure 1 ;

[0029] Figure 8 Schematic diagram of the structure with a transmission virtual position arranged between the tension swing shaft and the transmission swing rod Figure 2 ;

[0030] Reference numerals: 1, support film roller; 2, brake swing arm; 3, tension swing arm; 4, brake disc; 5, brake band; 6, transmission virtual position; 7, transmission connecting rod; 8, tension swing shaft; 9, transmission swing rod; 10, fixed connection joint; 11, floating connection joint; 12, limit groove; 13, limiting member; 14, wedge-shaped protrusion; 15, wedge-shaped slot; 16, tension spring; 17, tension adjustment assembly; 18, fixing nut; 19, adjusting bolt; 20, hanging ring; 21, frame. Detailed implementation manners

[0031] The following are exemplary embodiments in combination with the accompanying drawings to help comprehensively understand the present utility model defined by the claims and their equivalents, where the specific details will only be regarded as exemplary and will not limit the scope of the present utility model. Therefore, those of ordinary skill in the art can make various changes and modifications to the embodiments without departing from the scope and spirit of the present utility model.

[0032] As a preferred embodiment of the present utility model, this embodiment discloses a roll film braking device, which includes a support film roller 1, a brake swing arm 2 and a tension swing arm 3. A brake disc 4 is assembled on the support film roller 1, a brake band 5 adapted to the brake disc 4 is assembled on the brake swing arm 2, the tension swing arm 3 is in transmission connection with the brake swing arm 2, and a transmission virtual position 6 is arranged on the transmission structure between the tension swing arm 3 and the brake swing arm 2. The setting of the transmission virtual position 6 enables the tension swing arm 3 to swing a set angle first and then drive the brake swing arm 2 to act.

[0033] In the film winding brake device, the tension swing arm 3 and the brake swing arm 2 are generally not directly connected by transmission, but are connected through other transmission structures, such as transmission through the transmission connecting rod 7, or through the tension swing shaft 8 to drive the transmission swing rod 9, the transmission swing rod 9 is connected to the transmission connecting rod 7, and the transmission connecting rod 7 is connected to the brake swing arm 2. Or some other transmission structures.

[0034] In this embodiment, the transmission virtual position 6 can be set on any transmission connecting member on the transmission structure between the tension swing arm 3 and the brake swing arm 2. Or it can be set at the connection position between the two transmission connecting members, and the function of the present application can be realized.

[0035] The setting of the transmission virtual position 6 makes the transmission between the tension swing arm 3 and the brake swing arm 2 not respond immediately, causing the response of the brake swing arm 2 to lag. When the equipment is started, a force can be applied first to overcome the deadweight of the tension swing arm 3, and then the pulling force to drive the brake swing arm 2 to move and overcome the braking force can be gradually increased to avoid the packaging film being stretched and deformed due to excessive initial pulling force.

[0036] For example, when the equipment is stopped, the brake arm 2 is driven close to the brake disc 4 by the deadweight of the tension arm 3, and a braking force is formed between the brake band 5 and the brake disc 4. When there is no transmission dummy position 6, when the equipment is started, the tension F applied to the packaging film 拉 Need to overcome the tension swing arm 3 weight F 重 The braking force F formed between the brake band 5 and the brake disc 4 刹 , that is, F 拉 >F 重 + F 刹 At this time F 拉 If it is too large, the packaging film will be stretched and deformed.

[0037] After the transmission virtual position 6 is set, the tension swing arm 3 can first swing relative to the brake swing arm 2 by a set amplitude, which is determined according to the travel of the transmission virtual position 6. At this time, the tension applied to the packaging film only needs to meet F 拉 >F 重 That is, the deadweight of the tension swing arm 3 is overcome. When the tension swing arm 3 has completed the travel of the transmission virtual position 6, the tension swing arm 3 continues to swing and drives the brake swing arm 2. At this time, the tension applied to the packaging film increases to F 拉 >F 重 + F 刹That is, when the device is started, the pulling force applied to the packaging film increases step by step, which avoids the stretching deformation of the packaging film caused by excessive initial pulling force. After the swing of the tension swing arm 3 finishes the stroke of the transmission virtual position 6, if the tension swing arm 3 continues to swing, it will drive the brake swing arm 2 to swing, thereby changing the braking force of the brake band 5 on the brake disc 4 on the brake swing arm 2, and further adjusting the braking force to the force adapting to the film roll tension, and finally reaching the balancing device.

[0038] As an implementation manner of the present utility model, referring to the attached Figure 1 drawing and the attached Figure 2 As shown in the figure, a film roll braking device is shown. The device includes a frame 21, a support film roll 1, a brake swing arm 2 and a tension swing arm 3. The tension swing arm 3 and the support film roll 1 are located on one side of the frame 21. The end of the support film roll 1 passes through the frame 21 to assemble a brake disc 4. The brake disc 4 and the brake swing arm 2 are located on the other side of the frame 21. The tension swing arm 3 is connected to a tension swing shaft 8. Both ends of the tension swing shaft 8 are located on both sides of the frame 21. One end is connected to the tension swing arm 3 located on one side of the frame 21, and the other end is connected to a transmission swing rod 9 located on the other side of the frame 21. The transmission swing rod 9 is connected to the brake swing arm 2 through a transmission connecting rod 7. A brake band 5 is arranged on the brake swing arm 2.

[0039] Referring to the attached Figure 1 As shown in the figure, when the device is in a shutdown state, the tension swing arm 3 swings downward by its own weight, and the swing posture of the tension swing arm 3 is maintained by the packaging film passing around the film guide roller on the frame 21 and the film guide roller on the tension swing arm 3. At this time, the tension of the packaging film is maintained by the self-weight of the tension swing arm 3.

[0040] When the device is started, a film pulling mechanism (not shown in the figure) pulls the packaging film for conveying. At this time, the brake band 5 does not leave the brake disc 4, and the film roll is held stationary by the braking force. Then the tension of the packaging film increases, causing the tension swing arm 3 to swing upward, that is, shortening the distance between the film guide roller on the tension swing arm 3 and the film guide roller on the frame 21. When there is no transmission virtual position 6 set, when the tension swing arm 3 swings upward, it drives the transmission swing rod 9 to swing downward through the tension swing shaft 8. The transmission swing rod 9 drives the brake swing arm 2 to swing downward through the transmission connecting rod 7, reducing the acting force of the brake band 5 on the brake disc 4, thereby reducing the braking force, and the film roll rotates. When the device is running normally, the braking force is adjusted to the force adapting to the film roll tension, and finally the balancing device is reached.

[0041] Referring to the attached Figure 3 As shown in the figure, the attached Figure 3 shows the structure where the tension swing arm 3 and the brake swing arm 2 are on the same side of the frame 21. In this structure, a connecting ear plate is arranged at a position on the tension swing arm 3 close to the tension swing shaft 8. The transmission connecting rod 7 is connected through this connecting ear plate, and the transmission between the tension swing arm 3 and the brake swing arm 2 is realized through the transmission connecting rod 7.

[0042] Based on the instruction manual Figure 2 and attached Figure 3 The structures of the two film winding brake devices shown in the figure, when the transmission virtual position 6 is set, the transmission virtual position 6 can be set on the transmission connecting rod 7, refer to the attached manual Figure 5 and attached Figure 6 As shown, the transmission connecting rod 7 includes a fixed connection joint 10 and a floating connection joint 11, the floating connection joint 11 is connected to the fixed connection joint 10, and the floating connection joint 11 is telescopically set relative to the fixed connection joint 10 along the axis of the transmission connecting rod 7, and the displacement of the floating connection joint 11 relative to the fixed connection joint 10 forms the transmission virtual position 6. In this embodiment, the transmission virtual position 6 is set on the transmission connecting rod 7, the structure is simpler, and it is easier to implement. The modification of the existing film rolling brake device is relatively small, and it can be realized by only replacing the original transmission connecting rod 7 with the transmission connecting rod 7 with the transmission virtual position 6.

[0043] As an example of this embodiment, refer to the attached Figure 6 As shown, the floating connection joint 11 is plugged together with the fixed connection joint 10, a limiting groove 12 is provided on the fixed connection joint 10, and a limiting member 13 is provided on the floating connection joint 11 for limiting the position in cooperation with the limiting groove 12, and the displacement of the limiting member 13 on the floating connection joint 11 in the limiting groove 12 forms the transmission virtual position 6.

[0044] As another implementation structure of this embodiment, refer to the attached Figure 4 As shown, attached Figure 4 The structure of the brake swing arm 2 connected to the tension spring 16 is shown. At this time, there is no transmission connection between the transmission swing arm 9 and the brake swing arm 2. Instead, the transmission swing arm 9 is in contact with the brake swing arm 2. When the transmission swing arm 9 swings, the brake swing arm 2 is lifted up, thereby realizing the adjustment of the braking force. Figure 4 In the structure shown, when there is no transmission virtual position 6, the initial tension needs to overcome the deadweight of the tension swing arm, the braking force and the elastic force of the tension spring 16. The initial tension is greater and is more likely to cause tensile deformation of the packaging film.

[0045] And the structure of the above embodiment of the attached Figure 2 and attached Figure 3 In the film winding brake device structure shown, the transmission virtual position 6 can be arranged on the tension swing shaft 8 transmitted between the tension swing arm 3 and the transmission swing rod 9. Or it can be arranged between the tension swing shaft 8 and the transmission swing rod 9.

[0046] As an example of this embodiment, refer to the attached Figure 7As shown, the tension swing shaft 8 is fixedly connected to the end of the tension swing arm 3. A wedge-shaped protrusion 14 is provided at the end of the transmission swing rod 9 assembled on the tension swing shaft 8. A wedge-shaped slot 15 is provided in the mounting hole of the transmission swing rod 9 for assembling the tension swing shaft 8. The wedge-shaped protrusion 14 is correspondingly arranged in the wedge-shaped slot 15, and the radian of the wedge-shaped protrusion 14 is smaller than that of the wedge-shaped slot 15. The wedge-shaped protrusion 14 rotates a set angle in the wedge-shaped slot 15, driving the transmission swing rod 9 to rotate. The displacement of the wedge-shaped protrusion 14 in the wedge-shaped slot is the transmission virtual position 6.

[0047] As another example of this embodiment, refer to the appended drawings of the specification Figure 8 As shown, the tension swing shaft 8 is divided into two halves along its axial plane. One half is a sector smaller than a semi-circle. One half is fixed to the tension swing shaft 8, and the other half is fixed to the transmission swing rod 9. The relative displacement between the two halves of the tension swing shaft 8 is the transmission virtual position 6.

[0048] When the equipment stops running, when the film roll is relatively large, it usually loosens a lot under the action of inertia when stopping, releasing a part of the packaging film. At this time, the braking force has returned to the maximum state. With the intervention of the transmission virtual position 6, the tension swing arm 3 can swing for a certain stroke under its own weight (after the braking force reaches the maximum, the tension swing arm 3 can continue to swing along the transmission virtual position 6), which can keep the packaging film in a tension balance state, avoiding the problem of unstable color mark induction due to the too loose film roll during the next start-up, resulting in too large a deviation in the length of the packaging bag.

[0049] As another example of this embodiment, refer to the appended drawings of the specification Figure 2 and appended Figure 4As shown, a tension spring 16 is connected to the brake swing arm 2. One end of the tension spring 16 is connected to the swing end of the brake swing arm 2, and the other end is connected to the frame 21 of the film winding brake device. The other end of the tension spring 16 is connected to the frame 21 of the film winding brake device through a tension adjustment assembly 17. The tension adjustment assembly 17 includes a fixing nut 18 fixed on the frame 21 of the film winding brake device, an adjustment bolt 19 threadedly engaged with the fixing nut 18, and a hanging ring 20 adapted to the hook of the tension spring 16 provided at the end of the adjustment bolt 19. By providing the tension spring 16 on the brake swing arm 2, when the device stops, in the absence of the support of the tension swing arm 3, the tension spring 16 can pull the brake swing arm 2 to quickly restore the braking force. Under the action of the transmission play 6, the tension swing arm 3 can swing with a certain stroke under its own weight, enabling the packaging film to maintain a tension balance state, avoiding the problem of unstable color mark induction caused by the too loose film roll during the next startup, which may lead to an excessive deviation in the length of the packaging bag. At the same time, the setting of the tension spring 16 can also adjust the tension according to the wear condition of the brake band 5, so that the braking force can be adjusted and adapted to follow the wear of the brake band 5, and the braking force can be adjusted to a strength suitable for the film roll tension.

[0050] Although the inventive concept of the present invention has been specifically shown and described with reference to the exemplary embodiments of the present invention, those skilled in the art should understand that various changes in form and details can be made without departing from the spirit and scope of the present invention defined by the claims.

Claims

1. A roll film braking device, which comprises a support film roller (1), a braking swing arm (2) and a tension swing arm (3). A brake disc (4) is assembled on the support film roller (1). A brake band (5) adapted to the brake disc (4) is assembled on the braking swing arm (2). The tension swing arm (3) is in transmission connection with the braking swing arm (2), and is characterized in that: A transmission virtual position (6) is provided on the transmission structure between the tension swing arm (3) and the brake swing arm (2). The setting of the transmission virtual position (6) enables the tension swing arm (3) to swing by a set angle first and then drive the brake swing arm (2) to act.

2. The roll film braking device according to claim 1, characterized in that: The tension swing arm (3) and the brake swing arm (2) are connected by a transmission connecting rod (7), and the transmission virtual position (6) is provided on the transmission connecting rod (7).

3. The roll film braking device according to claim 1, characterized in that: The tension swing arm (3) swings around a tension swing shaft (8). A transmission swing rod (9) is coaxially assembled on the tension swing shaft (8). The transmission swing rod (9) is connected to the brake swing arm (2) through a transmission connecting rod (7); the transmission virtual position (6) is provided on the transmission connecting rod (7).

4. A roll film braking device according to claim 2 or 3, characterized in that: The transmission connecting rod (7) includes a fixed connection joint (10) and a floating connection joint (11). The floating connection joint (11) is connected to the fixed connection joint (10), and the floating connection joint (11) is displaced along the axis of the transmission connecting rod (7) relative to the fixed connection joint (10). The displacement of the floating connection joint (11) relative to the fixed connection joint (10) forms the transmission virtual position (6).

5. The roll film braking device according to claim 4, wherein: The floating connection joint (11) is inserted into the fixed connection joint (10). A limit groove (12) is provided on the fixed connection joint (10), and a limit member (13) that cooperates with the limit groove (12) for limiting is provided on the floating connection joint (11). The displacement of the limit member (13) on the floating connection joint (11) in the limit groove (12) forms the transmission virtual position (6).

6. The roll film braking device according to claim 1, characterized in that: The tension swing arm (3) swings around a tension swing shaft (8). A transmission swing rod (9) is coaxially assembled on the tension swing shaft (8). The transmission swing rod (9) is connected to the brake swing arm (2); the transmission virtual position (6) is provided on the tension swing shaft (8) for the transmission between the tension swing arm (3) and the transmission swing rod (9).

7. The winding film braking device according to claim 6, characterized in that: The tension swing shaft (8) is fixedly connected to the end of the tension swing arm (3). A wedge-shaped protrusion (14) is provided at the end of the tension swing shaft (8) for assembling the transmission swing rod (9). A wedge-shaped slot (15) is provided in the mounting hole of the transmission swing rod (9) for assembling the tension swing shaft (8). The wedge-shaped protrusion (14) is correspondingly arranged in the wedge-shaped slot (15), and the radian of the wedge-shaped protrusion (14) is smaller than the radian of the wedge-shaped slot (15). The wedge-shaped protrusion (14) rotates by a set angle in the wedge-shaped slot (15), and the wedge-shaped protrusion (14) drives the transmission swing rod (9) to rotate. The displacement of the wedge-shaped protrusion (14) in the wedge-shaped slot (15) is the transmission virtual position (6).

8. A roll film braking device according to any one of claims 1-3 or 6-7, characterized in that: A tension spring (16) is connected to the brake swing arm (2). One end of the tension spring (16) is connected to the swing end of the brake swing arm (2), and the other end is connected to the frame (21) of the film winding brake device.

9. The roll film braking device according to claim 8, characterized in that: The other end of the tension spring (16) is connected to the frame (21) of the film winding brake device through a tension adjusting assembly (17).

10. A roll film braking device according to claim 9, characterized in that: The tension adjusting assembly (17) includes a fixing nut (18) fixed on the frame (21) of the film winding braking device, an adjusting bolt (19) threadedly engaged with the fixing nut (18), and a hanging ring (20) adapted to the hook of the tension spring (16) provided at the end of the adjusting bolt (19).

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