Shaftless film unwinding device and bag making machine

Abstract

The utility model relates to the technical field of bag making machines, in particular to a film shaftless unwinding device and a bag making machine, which comprise a rack and an unwinding component, the unwinding component is assembled with the rack, the unwinding component comprises a cylinder, two groups of unwinding seats and two groups of plugs, the two groups of unwinding seats are arranged at intervals along the longitudinal direction of the rack, and the two groups of plugs are arranged at intervals along the longitudinal direction of the rack. The two sets of plugs are arranged in a mirror image mode and assembled on the inner side walls of the two sets of unwinding bases correspondingly, the plugs are conical, the two sets of plugs include the first plug and the second plug, the air cylinder is assembled on the outer side walls of the unwinding bases and used for pushing the first plug to move back and forth towards the second plug, and the air cylinder is assembled on the outer side walls of the unwinding bases and used for pushing the second plug to move back and forth towards the second plug. The conical plug is adopted as a positioning and locking element, unwinding of film rolls of multiple specifications is achieved, the plug on one side is driven by the air cylinder to move linearly, opening and closing actions of the plug and the fixed plug are achieved, roll changing and clamping of the film rolls are facilitated, and roll changing efficiency is improved.

Description

Technical Field

[0001] This utility model relates to the field of bag making machine technology, and in particular to a film shaftless unwinding device and a bag making machine. Background Technology

[0002] Bag-making machines are core production equipment in the flexible packaging industry. Their core processing principle involves unwinding two rolls of film material via an unwinding device, then being pulled, unfolded, and precisely aligned by multiple sets of guide rollers before being overlapped and laminated. Finally, they are heat-sealed and cut to produce packaging bags. The film roll consists of film wound onto a core cylinder.

[0003] Currently, the feeding and unwinding of film rolls generally uses an air shaft solution. During operation, the air shaft must first be inserted into the core tube and inflated, then supported at both ends on the unwinding frame for unwinding. This method has two major drawbacks: First, it has poor compatibility. With various core tube inner diameters, multiple sets of air shafts of different specifications are needed to meet production requirements, increasing equipment costs and the complexity of air shaft storage and management. Second, it has low feeding efficiency. Changing rolls requires first loading and unloading the air shaft, preventing direct installation of the film roll. Repeated loading and unloading of the air shaft increases operational steps and time, impacting production efficiency.

[0004] Therefore, it is necessary to design a film unwinding device that does not require an air shaft to improve the compatibility and feeding efficiency of the unwinding device. Utility Model Content

[0005] In view of the fact that the existing technology requires the use of an air shaft for installation when unwinding film rolls, which has problems with compatibility and installation inconvenience, this application provides a shaftless unwinding device for film and a bag making machine.

[0006] Firstly, the present invention provides a shaftless unwinding device for thin films, which adopts the following technical solution:

[0007] A shaftless unwinding device for thin films includes a frame and an unwinding assembly. The unwinding assembly is assembled with the frame. The unwinding assembly includes a cylinder, two sets of unwinding seats, and two sets of plugs. The two sets of unwinding seats are arranged longitudinally and spaced apart along the frame. The two sets of plugs are mirror images of each other and are respectively assembled on the inner sidewalls of the two sets of unwinding seats. The plugs are conical. The two sets of plugs are a first plug and a second plug. The cylinder is assembled on the outer sidewall of the unwinding seat and is used to push the first plug to move back and forth toward the second plug.

[0008] Preferably, the conical surface of the plug has multiple sets of grooves, and the multiple sets of grooves are arranged at intervals along the axis of the plug.

[0009] Preferably, the plug is provided with a first conical surface and a second conical surface, the diameter of the first conical surface is smaller than the diameter of the second conical surface, and the second conical surface is located close to the unwinding seat.

[0010] Preferably, the unwinding assembly further includes an outer sleeve and an inner sleeve. The outer sleeve is connected to the outer wall of the unwinding seat, and the inner sleeve is slidably assembled in the outer sleeve. The fixed end of the cylinder is connected to the outer sleeve, and the pushing end of the cylinder is connected to the inner sleeve. The first plug is rotatably assembled with the inner sleeve.

[0011] Preferably, the unwinding assembly further includes a magnetic powder brake, the second plug is rotatably assembled with another set of unwinding seats, and the magnetic powder brake is assembled with the unwinding seats and is used to brake the second plug.

[0012] Preferably, the unwinding assembly further includes a driving pulley, a driven pulley, and a timing belt. The fixed end of the magnetic powder brake is connected to the unwinding seat, the rotating end of the magnetic powder brake is axially connected to the driving pulley, the driven pulley is axially connected to the second end cap, and the timing belt is sleeved between the driving pulley and the driven pulley.

[0013] Preferably, it further includes an adjustment and locking assembly, wherein the unwinding seat is slidably assembled with the frame, and the adjustment and locking assembly is assembled between the unwinding seat and the frame, and is used to adjust and lock the position of the unwinding seat.

[0014] Preferably, the adjusting locking assembly includes a rack and a gear. The rack is connected to the frame, and the gear is assembled with the unwinding seat and moves back and forth along the transverse direction of the rack. When the unwinding seat is slidably adjusted, the gear slides away from the rack, causing the unwinding seat to slide against the frame.

[0015] Preferably, the adjusting locking assembly further includes a pull handle, a fixed seat, a connecting shaft, and a spring. The fixed seat is connected to the unwinding seat and has a transverse through-hole. The connecting shaft passes through the through-hole and one end is connected to the gear. The other end of the connecting shaft is connected to the pull handle. The connecting shaft has a shoulder. The inner ring of the spring is fitted around the connecting shaft and its two ends abut against the inner wall of the shoulder and the through-hole, respectively.

[0016] Secondly, the bag-making machine provided by this utility model adopts the following technical solution:

[0017] A bag making machine includes the aforementioned shaftless unwinding device for film, and also includes a bag making machine body. The shaftless unwinding device for film is located on the feeding side of the bag making machine body and is used for feeding and unwinding film rolls.

[0018] The beneficial effects of this utility model are as follows:

[0019] By using a conical plug as a positioning and locking element to replace the traditional air shaft, the compatibility problem of the unwinding device with film cores of different inner diameters is solved, enabling unwinding of film rolls of various specifications and reducing the procurement, management, and replacement costs of air shafts of various specifications. Secondly, by using a cylinder to drive the plug on one side to move linearly, the opening and closing action with the fixed plug is realized, eliminating the repetitive operation steps of pre-loading and unloading the air shaft during the film roll feeding process, facilitating film roll changing and clamping, and improving changing efficiency.

[0020] By setting up an outer sleeve and an inner sleeve that slide together to act as a transmission medium between the cylinder and the first plug, the problem of the cylinder push rod not being able to rotate while the first plug needs to rotate continuously is solved. This achieves functional decoupling between the axial clamping force transmission and the circumferential rotational motion, enabling the smooth operation of the film winding and unwinding.

[0021] By controlling the magnetic powder brake to brake the second plug, the film roll can be quickly and accurately aligned and assembled with the second plug, improving the stability and efficiency of the feeding process. When the other end of the film roll is tightened by the first plug, the magnetic powder brake is controlled to release the brake on the second plug, thereby enabling the second plug to rotate and allowing the film roll to be unwound.

[0022] By incorporating an adjustment and locking assembly, pulling the handle pulls the connecting shaft, overcoming the spring force, causing the gear and rack to disengage, allowing the unwinding seat to slide. This adjusts the length between the first and second plugs, thus matching film rolls of different lengths and improving the equipment's compatibility with various film roll specifications. Attached Figure Description

[0023] Figure 1 This is a top view of Embodiment 1 of this application;

[0024] Figure 2 yes Figure 1 A magnified view of a section at point A in the middle;

[0025] Figure 3 yes Figure 1 A magnified view of a section at point B in the middle;

[0026] Figure 4 This is the front view in Embodiment 1 of this application;

[0027] Figure 5 This is the left view in Embodiment 1 of this application;

[0028] Figure 6 yes Figure 5 Enlarged view of a section at point C;

[0029] Figure 7 This is the right view in Embodiment 1 of this application;

[0030] Figure 8 This is a perspective view of the plug in Embodiment 1 of this application;

[0031] Figure 9 This is a cross-sectional view of the plug in Embodiment 1 of this application. Figure 1 ;

[0032] Figure 10 This is a schematic diagram of the plug and unwinding shaft in Embodiment 1 of this application;

[0033] Figure 11 This is a cross-sectional view of the plug in Embodiment 1 of this application. Figure 2 ;

[0034] Figure 12 This is a partial schematic diagram of the adjusting locking component in Embodiment 1 of this application;

[0035] Figure 13 This is a schematic diagram of the slide rail and slider assembly in Embodiment 1 of this application;

[0036] Explanation of reference numerals in the attached drawings: 1. Frame; 2. Unwinding assembly; 201. Cylinder; 202. Unwinding seat; 203. Plug; 2031. First plug; 2032. Second plug; 2033. Groove; 2034. First conical surface; 2035. Second conical surface; 2036. Mounting groove; 2037. Keyway; 204. Outer sleeve seat; 205. Inner sleeve seat; 206. Magnetic powder brake; 207. Drive pulley; 208. Driven pulley; 209. Synchronous belt; 210. Unwinding shaft; 211. Bearing; 3. Adjustment and locking assembly; 301. Rack; 302. Gear; 303. Pull handle; 304. Fixed seat; 3041. Connecting hole; 305. Connecting shaft; 306. Spring; 307. Slider; 308. Slide rail. Detailed Implementation

[0037] This section will describe in detail the specific embodiments of this application. Preferred embodiments of this application are shown in the accompanying drawings. The purpose of the drawings is to supplement the textual description with graphics, so as to intuitively and vividly understand each technical feature and overall technical solution of this application, but they should not be construed as limiting the scope of protection of this application.

[0038] In the description of this application, if directional descriptions are involved, such as "up," "down," "front," "back," "left," "right," etc., indicating the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, it is only for the convenience of describing this application and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application. When a feature is referred to as "set," "fixed," or "connected" to another feature, it can be directly set, fixed, or connected to the other feature, or it can be indirectly set, fixed, or connected to the other feature.

[0039] In the description of this application, if directional descriptions are involved, such as "lateral," "longitudinal," or "vertical," indicating directional or positional relationships, these are based on the appendix. Figure 4 and Figure 5 The orientation or positional relationship shown is represented by the X-axis as "horizontal", the Y-axis as "vertical", and the Z-axis as "vertical".

[0040] In the description of this application, the term "several" means one or more, and "more than" means two or more. The terms "greater than," "less than," and "exceeding" should be understood as excluding the stated number, while "above," "below," and "within" should be understood as including the stated number. The terms "first" and "second" should be understood as distinguishing technical features and not as indicating or implying relative importance, the number of indicated technical features, or the order of the indicated technical features.

[0041] Furthermore, unless otherwise defined, the technical and scientific terms used in this application have the same meanings as commonly understood by one of ordinary skill in the art. The terminology used in this application is for the purpose of describing particular embodiments only and not for limiting the application. It should be understood that, when used in this specification and the appended claims, the terms "comprising" and "including" indicate the presence of the described features, integrals, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components, and / or collections thereof.

[0042] Example 1: As Figure 1-13As shown, a shaftless unwinding device for thin films includes a frame 1 and an unwinding assembly 2. The unwinding assembly 2 is assembled with the frame 1. The unwinding assembly 2 includes a cylinder 201, two sets of unwinding seats 202, and two sets of plugs 203. The two sets of unwinding seats 202 are arranged longitudinally at intervals along the frame 1. The two sets of plugs 203 are mirror images of each other along the central reference plane between the two sets of unwinding seats 202 and are respectively assembled on the inner sidewalls of the two sets of unwinding seats 202. The axes of the two sets of plugs 203 are collinear. The plugs 203 are tapered. The end of the plug 203 near the unwinding seat 202 gradually tilts and contracts towards the end away from the unwinding seat 202. The two sets of plugs 203 are a first plug 2031 and a second plug 2032, respectively. The cylinder 201 is assembled on the outer sidewall of the unwinding seat 202 and is used to push the first plug 2031 back and forth toward the second plug 2032.

[0043] During operation, the control cylinder 201 moves one set of plugs 203 away from the other set of plugs 203. Then, the film roll is fed until one end of the core tube contacts the outer ring wall of the second plug 2032, and the other end of the core tube is flush with the height of the first plug 2031. Then, the control cylinder 201 moves the first plug 2031 toward the second set of plugs 203, and the tapered surface of the plug 203 abuts against the inner wall of the core tube, thereby completing the feeding of the film roll.

[0044] By using a conical plug 203 as a positioning and locking element to replace the traditional air shaft, the compatibility problem of the unwinding device with film cores of different inner diameters is solved, enabling unwinding of film rolls of various specifications and reducing the procurement, management, and replacement costs of air shafts of various specifications. Secondly, by using a cylinder 201 to drive the plug 203 on one side to move linearly, the opening and closing action with the fixed plug 203 is realized, eliminating the repetitive operation steps of pre-loading and unloading the air shaft during the film roll feeding process, facilitating film roll changing and clamping, and improving changing efficiency.

[0045] The unwinding assembly 2 is provided in two sets, and the two sets of unwinding assemblies 2 are arranged vertically along the frame 1 to unwind the upper and lower rolls of film material.

[0046] Because the core tube is made of paper core, in order to assemble the plug 203 with the core tube, in terms of the specific structural design of the plug 203, multiple sets of grooves 2033 are opened on the conical surface of the plug 203. The multiple sets of grooves 2033 are arranged at equal angles along the axis of the plug 203. By setting the plug 203 with grooves 2033, the assembly stability of the core tube is improved.

[0047] To enable the plug 203 to accommodate two different commonly used inner diameter sizes of mandrels, thereby reducing the continuous conical surface and preventing the overall axial length of the plug 203 from becoming too long, the plug 203 is provided with a first conical surface 2034 and a second conical surface 2035. The diameter of the first conical surface 2034 is smaller than the diameter of the second conical surface 2035, and the second conical surface 2035 is located close to the unwinding seat 202. By designing the plug 203 with a first conical surface 2034 and a second conical surface 2035 of different diameters, the problem of the excessively long axial dimension of the plug 203 caused by using a single long conical surface to accommodate two inner diameter sizes is solved. This achieves the goal of accommodating two main specifications of mandrels within a limited space and optimizes the structural compactness of the plug 203.

[0048] The cone angle α of the first cone surface 2034 and the second cone surface 2035 is 18~22°.

[0049] In order to make the plug 203 compatible with the air shaft and further improve the compatibility of the unwinding device, the end of the plug 203 away from the unwinding seat 202 is provided with a mounting groove 2036. The mounting groove 2036 is used to insert the air shaft to achieve compatibility with the air shaft film roll.

[0050] Furthermore, if the film is wound on the printing plate cylinder, i.e., the core cylinder is the printing plate cylinder, the existing printing plate cylinder structure has a keyway 2037 inside the printing plate cylinder. In order to make the plug 203 compatible with it, the tapered surface of the plug 203 has a keyway 2037. When it is necessary to unwind the film roll with the printing plate cylinder as the core cylinder, a key bar is connected to the keyway 2037 by screws, which is aligned with the keyway 2037 of the printing plate cylinder to play a positioning and anti-slip role, thereby realizing the unwinding.

[0051] Since the end cap 203 needs to rotate during unwinding, but the push rod of the cylinder 201 cannot rotate continuously, in order to solve the above technical problem, in terms of the assembly structure of the first end cap 2031 and the cylinder 201, the unwinding assembly 2 also includes an outer sleeve 204 and an inner sleeve 205. The outer sleeve 204 is cylindrical and connected to the outer side wall of the unwinding seat 202. The inner sleeve 205 is slidably assembled in the outer sleeve 204. The fixed end of the cylinder 201 is connected to the outer sleeve 204, and the pushing end of the cylinder 201 is connected to the inner sleeve 205 and is used to push the inner sleeve 205 along the outer sleeve 202. The inner wall of 04 moves back and forth, and the first plug 2031 is rotated and assembled with the inner sleeve 205. When the cylinder 201 pushes, it pushes the first plug 2031 through the inner sleeve 205. The first plug 2031 and the inner sleeve 205 are rotated and assembled. By setting the outer sleeve 204 and the inner sleeve 205 that cooperate and slide with each other, as the transmission medium between the cylinder 201 and the first plug 2031, the problem that the cylinder 201 push rod cannot rotate while the first plug 2031 needs to rotate continuously is solved. The function of axial clamping force transmission and circumferential rotational motion is decoupled, so that the film winding and unwinding operation can proceed smoothly.

[0052] When feeding the film roll, one end needs to be installed with the second end cap 2032 first. Similarly, the second end cap 2032 needs to rotate during unwinding. However, the rotation of the second end cap 2032 during installation will cause the film roll to rotate, thus affecting the installation of the film roll. To solve the above technical problems, the unwinding assembly 2 also includes a magnetic powder brake 206. The second end cap 2032 is rotatably assembled with another set of unwinding seats 202. The magnetic powder brake 206 is assembled with the unwinding seat 202 and is used to brake the second end cap 2032. By providing a magnetic powder brake 206 on the side of the second plug 2032, the second plug 2032 can be braked by controlling the magnetic powder brake 206 when installing the film roll. This facilitates the quick and accurate alignment of the film roll with the second plug 2032, improving the stability and efficiency of the feeding process. When the other end of the film roll is first tightened, the magnetic powder brake 206 is controlled to release the brake on the second plug 2032, thereby enabling the rotation of the second plug 2032 and allowing the film roll to be unwound.

[0053] Regarding the assembly structure of the magnetic powder brake 206 and the second plug 2032, the unwinding assembly 2 also includes a drive pulley 207, a driven pulley 208, and a timing belt 209. The fixed end of the magnetic powder brake 206 is connected to the unwinding seat 202, and the rotating end of the magnetic powder brake 206 is axially connected to the drive pulley 207. The driven pulley 208 is axially connected to the second plug 2032. The timing belt 209 is sleeved between the drive pulley 207 and the timing belt 209 wheel for power transmission. The magnetic powder brake 206 and the second plug 2032 are connected through the transmission method of the timing belt 209 and the pulley, thus optimizing the installation layout of each component of the unwinding device.

[0054] Regarding the installation and assembly structure of the plug 203, the unwinding assembly 2 also includes an unwinding shaft 210 and a bearing 211. The end of the plug 203 away from the mounting groove 2036 is connected to the unwinding shaft 210, and the inner ring of the bearing 211 is axially connected to the unwinding shaft 210. Specifically, when the first plug 2031 on the cylinder 201 side is assembled, the outer ring of the bearing 211 is connected to the inner ring of the inner sleeve 205. When the second plug 2032 on the magnetic powder brake 206 side is assembled, the outer ring of the bearing 211 is connected to the unwinding seat 202 through the bearing 211 seat.

[0055] To accommodate unwinding of film rolls of different lengths, this embodiment also includes an adjustment and locking assembly 3. The unwinding base 202 is slidably assembled with the frame 1. The adjustment and locking assembly 3 is assembled between the unwinding base 202 and the frame 1 and is used to adjust and lock the position of the unwinding base 202. By moving the unwinding base 202 back and forth along the longitudinal direction of the frame 1, the length between the first end cap 2031 and the second end cap 2032 is adjusted, thereby matching film rolls of different lengths and improving the equipment's compatibility with film rolls of various specifications.

[0056] Regarding the specific structure of the adjusting locking assembly 3, the adjusting locking assembly 3 includes a rack 301 and a gear 302 that meshes with the teeth of the rack 301. The rack 301 is connected to the frame 1, and the gear 302 is assembled with the unwinding seat 202 and moves back and forth along the transverse direction of the rack 301. When the unwinding seat 202 is slidably adjusted, the gear 302 slides away from the rack 301, causing the unwinding seat 202 to slide against the frame 1. After the unwinding seat 202 has been adjusted, the gear 302 meshes with the rack 301, thereby locking the unwinding seat 202 against the frame 1. Locking is achieved through the meshing of the gear 302 and the rack 301, improving the reliability and stability of locking after the unwinding seat 202 has been slidably adjusted.

[0057] When the unwinding device is unwinding, the unwinding seat 202 and the frame 1 should be in a locked state. That is, in the assembly method of gear 302 and rack 301, in the reset state, they should be in a meshed locked state to ensure the stability of film roll unwinding. When adjusting the unwinding seat 202, the operator consciously disengages gear 302 and rack 301 to complete the sliding adjustment, thereby ensuring the reliability of operation. For this purpose, in terms of the specific structure of the sliding assembly of rack 301 and unwinding seat 202, the adjusting locking assembly 3 also includes a pull handle 303, a fixed seat 304, a connecting shaft 305, and a spring 306. The fixed seat 304 is connected to the unwinding seat 202, and the fixed seat 304 has a transverse through-hole 3041. The connecting shaft 305 passes through the through-hole and one end is connected to gear 302. The other end of the connecting shaft 305 is connected to the pull handle 303. The connecting shaft 305 is provided with a shoulder. The spring 3041... The inner ring of 6 is fitted with the connecting shaft 305, and its two ends abut against the inner wall of the shaft shoulder and the connecting hole respectively. When the spring 306 is in the reset state, the gear 302 and the rack 301 are engaged. When it is necessary to slide the unwinding seat 202, the connecting shaft 305 is pulled by pulling the handle 303 to overcome the elastic force of the spring 306, so that the gear 302 and the rack 301 are disengaged, allowing the unwinding seat 202 to slide. During this period, the handle 303 needs to be pulled so that the gear 302 and the rack 301 are disengaged during the adjustment. When the handle 303 is released, the gear 302 slides under the force of the spring 306, so that the gear 302 and the rack 301 are engaged, completing the locking of the unwinding seat 202. The continuous elastic force provided by the spring 306 keeps the gear 302 and the rack 301 engaged in normal state, so that the adjustment locking component 3 is in a safe state of default locking, improving the stability and safety of operation.

[0058] Regarding the structure of the unwinding base 202 slidingly assembled with the frame 1, the adjusting locking assembly 3 also includes a slide rail 308 and a slider 307. The slide rail 308 is connected to the frame 1, one side of the slider 307 is slidably assembled with the slide rail 308, and the other side of the slider 307 is connected to the unwinding base 202. A set of slide rails 308 is correspondingly provided with four sets of sliders 307. A set of unwinding bases is connected with two sets of sliders 307. The two sets of sliders 307 are arranged at intervals along the longitudinal direction of the unwinding base 202. There are two sets of slide rails 308, and the two sets of slide rails 308 are arranged at intervals along the vertical direction of the unwinding base 202, thereby improving the stability of the unwinding base 202 sliding.

[0059] To facilitate the adjustment of the unwinding seat 202, scale lines are engraved on the side wall of the frame 1 at the location corresponding to the rack 301. This allows for the calculation of the difference between different lengths of film rolls to determine the adjustment amount of the unwinding seat 202 on one side.

[0060] It is worth mentioning that this embodiment also includes a processor, a cylinder 201 control button, and a magnetic powder brake 206 control button. The cylinder 201 control button is electrically connected to the processor and is used to input the push signal of the cylinder 201. The processor is electrically connected to the cylinder 201 and is used to output the push command of the cylinder 201. The magnetic powder brake 206 control button is electrically connected to the processor and is used to input the start and stop signal of the magnetic powder brake 206. The processor is electrically connected to the magnetic powder brake 206 and is used to output the start and stop command of the magnetic powder brake 206. The cylinder 201 control button and the magnetic powder brake 206 control button are respectively installed on the unwinding base 202 near the corresponding side of the cylinder 201 and the magnetic powder brake 206 for easy operation control.

[0061] Example 2: Figure 1-13 As shown, a bag making machine includes a film shaftless unwinding device as described in Embodiment 1, and also includes a bag making machine body. The film shaftless unwinding device is located on the feeding side of the bag making machine body and is used for feeding and unwinding film rolls.

[0062] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in this application, and these modifications or substitutions should all be covered within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A film off-axis unwinding device characterized by: The application relates to a thin-film shaftless unwinding device, which comprises a rack and an unwinding assembly assembled with the rack, wherein the unwinding assembly comprises a cylinder, two groups of unwinding seats, two groups of plugs, an outer sleeve seat and an inner sleeve seat; the two groups of unwinding seats are arranged along the longitudinal direction of the rack; the two groups of plugs are arranged in a mirror image mode and are assembled on the inner side walls of the two groups of unwinding seats respectively; the plugs are arranged in a tapered mode; the two groups of plugs are a first plug and a second plug respectively; the cylinder is assembled on the outer side wall of the unwinding seat and is used for pushing the first plug to move back and forth towards the second plug; the outer sleeve seat is connected with the outer side wall of the unwinding seat; the inner sleeve seat is slidingly assembled in the outer sleeve seat; the fixed end of the cylinder is connected with the outer sleeve seat; the pushing end of the cylinder is connected with the inner sleeve seat; and the first plug is rotationally assembled with the inner sleeve seat.

2. A film off-axis unwinding device according to claim 1, characterized in that: The plug is provided with a first taper surface and a second taper surface; the diameter of the first taper surface is smaller than that of the second taper surface; and the second taper surface is arranged close to the unwinding seat.

3. A film off-axis unwinding device according to claim 1 or 2, characterized in that: The taper surface of the plug is provided with a plurality of grooves; and the plurality of grooves are arranged along the axis of the plug.

4. The film off-axis unwinding device of claim 2, wherein: The taper angle a of the first taper surface is 18-22 DEG.

5. The film off-axis unwinding device of claim 1, wherein: The unwinding assembly further comprises a magnetic powder brake; the second plug is rotationally assembled with another group of unwinding seats; and the magnetic powder brake is assembled with the unwinding seat and is used for braking the second plug.

6. A film off-axis unwinding device according to claim 5, characterized in that: The unwinding assembly further comprises a driving pulley, a driven pulley and a synchronous belt; the fixed end of the magnetic powder brake is connected with the unwinding seat; the rotating end of the magnetic powder brake is connected with the driving pulley; the driven pulley is connected with the second plug; and the synchronous belt is sleeved between the driving pulley and the driven pulley.

7. The film off-axis unwinding device of claim 1, wherein: The application further comprises an adjusting and locking assembly; the unwinding seat is slidingly assembled with the rack; the adjusting and locking assembly is assembled between the unwinding seat and the rack and is used for adjusting and locking the position of the unwinding seat.

8. A film off-axis unwinding device according to claim 7, characterized in that: The adjusting and locking assembly comprises a rack and a gear; the rack is connected with the rack; the gear is assembled with the unwinding seat and moves back and forth along the transverse direction of the rack; when the unwinding seat is slidingly adjusted, the gear slides away from the rack so that the unwinding seat slides with the rack.

9. A film off-axis unwinding device according to claim 8, characterized in that: The adjusting and locking assembly further comprises a pulling handle, a fixed seat, a connecting shaft and a spring; the fixed seat is connected with the unwinding seat and is provided with a communication hole penetrating through the transverse direction; the connecting shaft is arranged in the communication hole and one end of the connecting shaft is connected with the gear; the other end of the connecting shaft is connected with the pulling handle; the connecting shaft is provided with a shaft shoulder; and the inner ring of the spring is sleeved with the connecting shaft and the two ends of the spring are respectively abutted against the shaft shoulder and the inner wall of the communication hole.

10. A bag making machine characterized by: The application further comprises a bag making machine body; and the thin-film shaftless unwinding device is arranged on the feeding side of the bag making machine body and is used for feeding and unwinding the thin-film roll.

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