Positioning device of paper-plastic composite glazing machine

Abstract

The utility model relates to the field of paper-plastic composite bag production, in particular to a positioning device of a paper-plastic composite glazing machine, which comprises a support, a positioning device and a positioning device, the limiting assembly comprises a limiting frame and two limiting rollers, the limiting frame is installed on the support, the two limiting rollers are rotationally installed on the limiting frame and are arranged at intervals in the radial direction of the movement track of the kraft paper, and limiting grooves allowing the kraft paper to penetrate through are coaxially formed in the wheel faces of the limiting rollers; and the tensioning assembly comprises two tensioning roller sets and an adjusting piece, the two tensioning roller sets are arranged at intervals along the movement track of the kraft paper and located on the two sides of the limiting roller wheel correspondingly, gaps allowing the kraft paper to penetrate through are formed in the tensioning roller sets, and the adjusting piece is used for adjusting the positions of the two tensioning roller sets. Kraft paper is limited through the limiting rollers, and the tensioning force of the kraft paper is adjusted when the glazing machine works by adjusting the tensioning roller set, so that the influence of adjustment of the position of the kraft paper on the production speed of a kraft paper laminating film is reduced.

Description

Technical Field

[0001] The present application relates to the field of paper-plastic composite bag production, and in particular to a positioning device for a paper-plastic composite lidding machine. Background Art

[0002] In order to improve the waterproof and moisture-proof properties of kraft paper, a layer of plastic film similar to OPP film will be compounded on the outer surface of the kraft paper packaging bag so that the packaging bag can be used to package fertilizers, grains, chemical products and other products.

[0003] The paper-plastic composite laminating machine is a device for laminating kraft paper. When it is working, the kraft paper and OPP film are moved to the hot pressing roller together under the guidance of the roller group. The adhesive layer of the OPP film faces the surface of the kraft paper. Then the kraft paper and OPP film pass through the hot pressing roller together. The hot pressing roller heats the adhesive layer of the OPP film to melt it, thus achieving the bonding and lamination of the OPP film and kraft paper.

[0004] When kraft paper contacts the surface of the hot pressing roller, it will produce some slight deformation due to the increase in temperature. Over time, it will affect the tension between the kraft paper and the roller group, causing the friction between the kraft paper and the roller to gradually decrease. The kraft paper itself is more likely to shift its moving position due to external factors such as collisions, requiring the operator to stop the machine from time to time to adjust the position of the kraft paper, thus affecting the lamination speed of the kraft paper. Utility Model Content

[0005] In order to reduce the influence of adjusting the position of kraft paper on the kraft paper laminating output speed, the present application provides a positioning device for a paper-plastic composite covering machine.

[0006] This application provides a technical solution that adopts the following:

[0007] A positioning device for a paper-plastic composite capping machine, comprising:

[0008] A bracket, mounted on the capping machine and located between the roller set and the hot pressing roller;

[0009] The limiting assembly comprises a limiting frame and a limiting roller, wherein the limiting frame is mounted on the bracket, two limiting rollers are provided and the two limiting rollers are radially spaced along the moving track of the kraft paper, the wheel surfaces of the two limiting rollers are arranged opposite to each other and are both rotatably mounted on the limiting frame, and the wheel surfaces of the limiting rollers are coaxially provided with limiting grooves for the kraft paper to pass through;

[0010] The tensioning assembly includes a tensioning roller group and an adjusting member. Two tensioning roller groups are arranged at intervals along the moving track of the kraft paper, and the two tensioning roller groups are respectively located on both sides of the limiting roller. A gap is provided on the tensioning roller group for the kraft paper to pass through. The adjusting member connects the two tensioning roller groups and is used to adjust the positions of the two tensioning roller groups.

[0011] By adopting the above technical solution, when the kraft paper moves on the cover light machine, it first passes through one set of tension rollers, then passes through the limit groove and limits the radial position of the kraft paper through the limit groove to prevent the kraft paper from deviating. Finally, the kraft paper passes through another set of tension rollers and moves to the hot pressing roller for hot pressing lamination. When the friction between the kraft paper and the tension roller is reduced, the position of the tension roller group can be adjusted through the adjustment part, so as to adjust the tension between the tension roller group and the kraft paper through the change of its own position, so as to prevent the position of the kraft paper from being offset due to external factors. And the whole process does not need to stop, reducing the impact of adjusting the position of the kraft paper on the kraft paper lamination output speed, and improving the kraft paper lamination output speed.

[0012] Optionally, the tensioning roller group includes a tensioning support and a tensioning roller rotatably mounted on the tensioning support, and two tensioning rollers are radially arranged along the moving track of the kraft paper, and a gap is provided between the two tensioning rollers for the kraft paper to pass through.

[0013] By adopting the above technical solution, the kraft paper abuts against the two tensioning rollers and passes between the two tensioning rollers, so that the two tensioning rollers rotate as the kraft paper moves, and the kraft paper is limited by the tensioning force.

[0014] Optionally, one of the tensioning rollers is connected to a fine-tuning piece, and the fine-tuning piece includes a fine-tuning slider and a fine-tuning spring. The tensioning roller is rotatably connected to the fine-tuning slider around its own axis. The tensioning support is provided with a fine-tuning groove for the fine-tuning slider to slide in a direction close to the other tensioning roller. The fine-tuning spring is arranged along the sliding direction of the fine-tuning slider, and both ends of the fine-tuning spring are respectively connected to the fine-tuning slider and the tensioning support.

[0015] By adopting the above technical scheme, in order to improve the application range of the tensioning roller group, the position of one tensioning roller relative to the other tensioning roller can be adjusted, so that the two tensioning rollers can be used for kraft paper of different thicknesses. When the kraft paper is covered with a laminated film, the tensioning force between the kraft paper and the tensioning roller can be flexibly adjusted according to the thickness of the kraft paper.

[0016] Optionally, the adjusting member includes an adjusting frame and a rotating rod, the tensioning support is installed on the adjusting frame, the adjusting frame is connected to the rotating rod on both radial sides along the moving trajectory of the kraft paper, the rotating rod is rotatably connected to the bracket around its own axis, the axis of the rotating rod is perpendicularly intersected with the axis of the limiting roller, and the rotating rod is connected to a first driving member for controlling the rotation angle of the rotating rod.

[0017] By adopting the above technical solution, in normal operation, the two tension rollers are arranged horizontally. When the tension between the kraft paper and the tension roller needs to be adjusted, the first driving member drives the rotating rod to rotate, so that the two tension rollers rotate around the limiting roller, thereby changing the local movement trajectory of the kraft paper, so that the movement direction of the kraft paper before the two tension roller brackets changes multiple times, thereby increasing the tension between the kraft paper and the tension roller.

[0018] Optionally, the first driving member includes a first gear, a second gear and a first motor, the first gear is coaxially fixed to the rotating rod, the second gear is rotatably mounted on the bracket and meshes with the first gear, the first motor is mounted on the bracket and the output shaft is coaxially fixedly connected to the second gear.

[0019] By adopting the above technical solution, the first motor drives the second gear to rotate, thereby driving the rotating rod connected to the first gear to rotate. The rotation of the rotating rod drives the positions of the two sets of tensioning rollers to change, so as to achieve fine-tuning of the tension of the kraft paper.

[0020] Optionally, a guide ring is coaxially arranged on the limiting roller, one end of the guide ring is flat and fixed to a groove wall of the limiting groove arranged along the axial direction of the limiting roller, and the other end of the guide ring is hemispherical.

[0021] By adopting the above technical solution, when the position of the tension roller group changes, the position and angle of the kraft paper passing through the limit groove will also change slightly. When the kraft paper is in continuous contact with the edge of the limit groove, the probability of the kraft paper being damaged will increase. The guide ring increases the contact area with the kraft paper and guides the kraft paper to slide into the limit groove, thereby reducing the wear between the kraft paper and the edge of the limit groove and reducing the probability of kraft paper being damaged.

[0022] Optionally, a movable part is connected between the limit frame and the bracket, and the movable part includes a movable slide and a bidirectional screw. The movable slide is installed on the bracket, and the bidirectional screw is rotatably installed on the movable slide and radially arranged along the moving trajectory of the kraft paper. The limit frame is threadedly connected to the bidirectional screw along the axial direction of the bidirectional screw, and the movable slide is slidably connected to the limit frame.

[0023] By adopting the above technical solution, the distance between the two limiting rollers can be accurately adjusted by rotating the bidirectional lead screw to facilitate the use of kraft paper of different sizes.

[0024] Optionally, the bidirectional screw is connected to a second driving member for controlling the rotation of the bidirectional screw, the second driving member includes a second motor and a distance measuring sensor, the second motor is installed on the moving slide and the output shaft is coaxially connected to the bidirectional screw, the distance measuring sensor is installed on the groove wall of the limit groove, and the distance measuring sensors on the two limit rollers are radially arranged along the moving trajectory of the kraft paper.

[0025] By adopting the above technical solution, in order to achieve the limitation of kraft paper, it is necessary to limit the position of both sides of the kraft paper. The distance between the two limiting rollers can be sensed by the distance measuring sensor. The distance between the groove walls of the two limiting grooves is the width of the kraft paper. The rotation angle of the bidirectional lead screw is accurately controlled by the second motor, so that the kraft paper slides and abuts against the groove walls of the limiting groove when moving, so as to improve the limiting accuracy of the kraft paper.

[0026] In summary, the present application includes at least one of the following beneficial technical effects:

[0027] The radial position of the kraft paper is limited by the limit groove, and the position of the tension roller group can be adjusted by the adjusting piece, thereby adjusting the tension between the tension roller group and the kraft paper to prevent the kraft paper from being displaced due to external factors. And the whole process does not require stopping, reducing the impact of adjusting the position of the kraft paper on the kraft paper laminating speed, and increasing the kraft paper laminating speed;

[0028] The first driving member drives the rotating rod to rotate, so that the two tension roller groups rotate around the limiting roller, thereby changing the local movement trajectory of the kraft paper, so that the movement direction of the kraft paper before the two tension roller group brackets changes multiple times, thereby increasing the tension between the kraft paper and the tension roller group;

[0029] As the position of the tension roller group changes, the position and angle of the kraft paper passing through the limit groove will also change, increasing the continuous contact between the kraft paper and the edge of the limit groove. Therefore, the guide ring increases the contact area with the kraft paper and guides the kraft paper to slide into the limit groove, thereby reducing the wear between the kraft paper and the edge of the limit groove and reducing the probability of kraft paper damage. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is a working schematic diagram of the positioning device according to an embodiment of the present application.

[0031] Figure 2 It is a schematic diagram of the structure of the positioning device in the embodiment of the present application.

[0032] Figure 3 It is a schematic diagram of the connection between the limiting roller and the limiting frame in the embodiment of the present application.

[0033] Figure 4 It is a schematic diagram of the overall structure of the limiting component in the embodiment of the present application.

[0034] Description of reference numerals:

[0035] 100, positioning device; 200, roller set; 300, hot pressing roller;

[0036] 1. Bracket; 2. Limiting assembly; 21. Limiting frame; 22. Limiting roller; 221. Limiting groove; 23. Guide ring; 24. Moving member; 241. Moving slide plate; 242. Bidirectional lead screw; 25. Second driving member; 251. Second motor; 252. Distance measuring sensor; 3. Tensioning assembly; 31. Tensioning support; 311. Fine-tuning slide groove; 32. Tensioning roller group; 321. Tensioning roller; 33. Adjusting member; 331. Adjusting frame; 332. Rotating rod; 34. Fine-tuning member; 341. Fine-tuning slide block; 342. Fine-tuning spring; 35. First driving member; 351. First gear; 352. Second gear; 353. First motor. DETAILED DESCRIPTION

[0037] The following is combined with Figure 1-4 This application is described in further detail.

[0038] It should be noted that, in the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicating orientations or positional relationships are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0039] The embodiment of the present application discloses a positioning device for a paper-plastic composite capping machine.

[0040] Reference Figure 1 and Figure 2 The positioning device 100 includes a bracket 1, a limiting component 2 and a tensioning component 3.

[0041] As shown in the figure, when the positioning device 100 is in use, the bracket 1 is installed on the cover light machine and is located between the roller group 200 and the hot pressing roller 300. The limiting assembly 2 includes a limiting frame 21 and a limiting roller 22. The limiting frame 21 is installed on the bracket 1. Two limiting rollers 22 are provided and the two limiting rollers 22 are arranged radially and spaced along the moving track of the kraft paper. The wheel surfaces of the two limiting rollers 22 are arranged opposite to each other and are both rotatably installed on the limiting frame 21. Figure 3 As shown, the wheel surface of the limiting roller 22 is coaxially provided with a limiting groove 221 for the kraft paper to pass through.

[0042] Before the kraft paper moves to the hot pressing roller 300 , the kraft paper passes through the limiting groove 221 between the two limiting rollers 22 , and the kraft paper slides against the groove wall of the limiting groove 221 , and the radial position of the kraft paper is limited by the limiting groove 221 .

[0043] In addition, the tensioning assembly 3 includes a tensioning roller group 32 and an adjusting member 33. Two tensioning roller groups 32 are arranged at intervals along the moving track of the kraft paper, and the two tensioning roller groups 32 are respectively located on both sides of the limiting roller 22. The tensioning roller group 32 includes a tensioning support 31 and a tensioning roller 321 rotatably mounted on the tensioning support 31. The tensioning roller 321 is radially arranged along the moving track of the kraft paper and two tensioning rollers 321 are provided. A gap is provided between the two tensioning rollers 321 for the kraft paper to pass through. The adjusting member 33 connects the two tensioning roller groups 32 and is used to adjust the positions of the two tensioning roller groups 32.

[0044] When the kraft paper passes through one of the tension roller groups 32, the kraft paper slides and contacts with the two tension rollers 321 and drives the two tension rollers 321 to rotate together through friction. When the tension between the kraft paper and the tension rollers 321 decreases due to external factors, the contact force between the kraft paper and the tension rollers 321 decreases, and the kraft paper is easily touched by some external collisions, causing its position to deviate.

[0045] Therefore, the positions of the two tensioning roller groups 32 can be fine-tuned through the adjustment member 33, so that the tensioning force between the tensioning roller 321 and the kraft paper is maintained in a relatively balanced state. The entire positioning process does not require closing the light covering machine, thereby reducing the impact of adjusting the position of the kraft paper on the kraft paper laminating and output speed, thereby increasing the kraft paper laminating and output speed.

[0046] Reference Figure 2 and Figure 4 The adjusting member 33 includes an adjusting frame 331, a rotating rod 332 and a first driving member 35. The tensioning support 31 is mounted on the adjusting frame 331. The adjusting frame 331 is connected to the rotating rods 332 on both radial sides along the moving track of the kraft paper. The rotating rods 332 are rotatably connected to the bracket 1 around their own axis. The axis of the rotating rod 332 is perpendicularly intersected with the axis of the limiting roller 22. When the position of the tensioning roller group 32 needs to be fine-tuned, the rotating rod 332 is rotated to drive the positions of the two tensioning roller groups 32 to change. Since the positions of the hot pressing roller 300 and the roller group 200 are relatively fixed, the effect of fine-tuning the kraft paper can be achieved.

[0047] In order to make the rotating rod 332 more stable when rotating and to make the angle adjustment more accurate, as shown in the figure, the first driving member 35 includes a first gear 351, a second gear 352 and a first motor 353. The first gear 351 is coaxially fixed to the rotating rod 332, the second gear 352 is rotatably mounted on the bracket 1 and meshes with the first gear 351, and the first motor 353 is mounted on the bracket 1 and the output shaft is coaxially fixedly connected with the second gear 352, so that the rotating rod 332 is driven to rotate by the first motor 353.

[0048] Reference Figure 2 and Figure 4In order to use kraft paper of different thicknesses, one of the tension rollers 321 in the same tension roller group 32 is connected with a fine-tuning member 34, and the fine-tuning member 34 includes a fine-tuning slider 341 and a fine-tuning spring 342. The tension roller 321 is rotatably connected with the fine-tuning slider 341 around its own axis, and a fine-tuning slot 311 is provided on the tension support 31 for the fine-tuning slider 341 to slide in a direction close to another tension roller 321. The fine-tuning spring 342 is arranged along the sliding direction of the fine-tuning slider 341, and the two ends of the fine-tuning spring 342 are respectively connected to the fine-tuning slider 341 and the tension support 31.

[0049] Normally, the fine-tuning spring 342 is in an extended state. When kraft paper of different thicknesses enters between the two tensioning rollers 321, the fine-tuning spring 342 will contract to varying degrees, increasing the distance between the two tensioning rollers 321 and increasing the tension between the kraft paper.

[0050] In the initial state, the two tension roller groups 32 are arranged horizontally relative to each other. When the tensioning force needs to be fine-tuned, the rotating rod 332 rotates to drive the position of the tension roller group 32 to change. At this time, the movement trajectory of the kraft paper between the two tension roller groups 32 will also change. The kraft paper will pass through the limit groove 221 at an angle. At this time, the kraft paper will contact and rub against the edge of the limit groove 221, which can easily cause creases or even direct rupture of the kraft paper. In order to avoid the above situation as much as possible, referring to the figure, a guide ring 23 is coaxially arranged on the limit roller 22. One end of the guide ring 23 is a plane and fixed to the groove wall of the limit groove 221 arranged along the axial direction of the limit roller 22, and the other end of the guide ring 23 is hemispherical.

[0051] When the kraft paper passes through the limiting groove 221 at an angle, the kraft paper contacts the hemispherical end surface of the guide ring 23. Due to the shape of the guide ring 23 itself, it can not only increase the contact area with the kraft paper, but also guide the kraft paper to change its own moving direction, thereby reducing the creases on the kraft paper and avoiding damage to the kraft paper as much as possible.

[0052] When the kraft paper needs the limiting roller 22 to limit the radial position, the radially arranged side of the kraft paper needs to slide against the groove wall of the limiting groove 221, that is, the distance between the two limiting grooves 221 is the width of the kraft paper. Figure 2 and Figure 3 A moving member 24 is connected between the limiting frame 21 and the bracket 1 , and the moving member 24 includes a moving slide 241 and a bidirectional lead screw 242 .

[0053] Among them, the movable slide 241 is installed on the bracket 1, the bidirectional screw 242 is rotatably installed on the movable slide 241 and radially arranged along the moving trajectory of the kraft paper, the limiting frame 21 connected to the two limiting rollers 22 is threadedly connected to the bidirectional screw 242 along the axial direction of the bidirectional screw 242, and the movable slide 241 is slidably connected to the limiting frame 21 along the axial direction of the bidirectional screw 242 to guide the position adjustment of the limiting roller 22.

[0054] In addition, the bidirectional lead screw 242 is connected to a second driving member 25 for controlling the rotation of the bidirectional lead screw 242. The second driving member 25 includes a second motor 251 and a distance measuring sensor 252. The second motor 251 is installed on the moving slide 241 and the output shaft is coaxially connected to the bidirectional lead screw 242. The distance measuring sensor 252 is installed on the groove wall of the limiting groove 221. The distance measuring sensors 252 on the two limiting rollers 22 are radially arranged along the moving trajectory of the kraft paper.

[0055] When limiting the position of the kraft paper, the second motor 251 controls the bidirectional lead screw 242 to rotate, so that the two limiting rollers 22 move in the direction close to the kraft paper, and the distance between the two limiting rollers 22 can be accurately measured by the distance measuring sensor 252 until the distance between the two distance measuring sensors 252 is equal to the thickness of the kraft paper. After that, when the kraft paper passes through the two limiting grooves 221, the kraft paper can be accurately limited, thereby improving the efficiency of limiting the kraft paper and reducing the wear on the kraft paper.

[0056] The implementation principle of the positioning device 100 of a paper-plastic composite covering machine in the embodiment of the present application is as follows: when the kraft paper is hot-pressed, the bracket 1 is first installed between the roller group 200 and the hot pressing roller 300, and then according to the width of the kraft paper, the second motor 251 controls the bidirectional lead screw to rotate until the distance measuring sensor 252 senses that the distance between the two limit grooves 221 is the width of the kraft paper, and the bidirectional lead screw 242 stops rotating, and the kraft paper passes through one of the tensioning roller groups 32, the limit groove 221 and the other tensioning roller group 32 in turn, and finally the kraft paper moves to the hot pressing roller 300. When the tension between the kraft paper and the tensioning roller group 32 is reduced due to some factors during the hot pressing process, the first motor 353 controls the rotating rod 332 to rotate, and the positions of the two tensioning roller groups 32 change, thereby changing the moving length of the kraft paper between the hot pressing roller 300 and the roller group 200, thereby achieving the tensioning effect during the hot pressing process. The entire process does not require shutdown, reducing the impact of adjusting the position of the kraft paper on the kraft paper laminating output speed, and increasing the kraft paper laminating output speed.

[0057] The above are all preferred embodiments of the present application, and the protection scope of the present application is not limited thereto. Therefore, any equivalent changes made according to the structure, shape, and principle of the present application should be included in the protection scope of the present application.

Claims

1. A positioning device for a paper-plastic composite capping machine, characterized in that: include: A bracket (1) is installed on the capping machine and is located between the roller set (200) and the hot pressing roller (300); The limiting assembly (2) comprises a limiting frame (21) and a limiting roller (22), wherein the limiting frame (21) is mounted on the bracket (1), two limiting rollers (22) are provided and the two limiting rollers (22) are radially spaced along the moving track of the kraft paper, the wheel surfaces of the two limiting rollers (22) are arranged opposite to each other and are both rotatably mounted on the limiting frame (21), and the wheel surfaces of the limiting rollers (22) are coaxially provided with limiting grooves (221) for the kraft paper to pass through; The tensioning assembly (3) comprises a tensioning roller group (32) and an adjusting member (33), wherein two tensioning roller groups (32) are arranged at intervals along the moving track of the kraft paper and the two tensioning roller groups (32) are respectively located on both sides of the limiting roller (22), and a gap is provided on the tensioning roller group (32) for the kraft paper to pass through, and the adjusting member (33) connects the two tensioning roller groups (32) and is used to adjust the positions of the two tensioning roller groups (32).

2. The positioning device of the paper-plastic composite capping machine according to claim 1, characterized in that: The tensioning roller group (32) comprises a tensioning support (31) and a tensioning roller (321) rotatably mounted on the tensioning support (31); two tensioning rollers (321) are radially arranged along the moving track of the kraft paper; a gap is provided between the two tensioning rollers (321) for the kraft paper to pass through.

3. The positioning device of the paper-plastic composite capping machine according to claim 2, characterized in that: One of the tensioning rollers (321) is connected to a fine-tuning member (34), and the fine-tuning member (34) includes a fine-tuning slider (341) and a fine-tuning spring (342). The tensioning roller (321) is rotatably connected to the fine-tuning slider (341) around its own axis. The tensioning support (31) is provided with a fine-tuning groove (311) for the fine-tuning slider (341) to slide in a direction close to the other tensioning roller (321). The fine-tuning spring (342) is arranged along the sliding direction of the fine-tuning slider (341), and the two ends of the fine-tuning spring (342) are respectively connected to the fine-tuning slider (341) and the tensioning support (31).

4. The positioning device of the paper-plastic composite capping machine according to claim 2, characterized in that: The adjusting member (33) comprises an adjusting frame (331) and a rotating rod (332); the tensioning support (31) is mounted on the adjusting frame (331); the adjusting frame (331) is connected to rotating rods (332) on both radial sides along the moving track of the kraft paper; the rotating rod (332) is rotatably connected to the bracket (1) around its own axis; the axis of the rotating rod (332) is perpendicularly intersected with the axis of the limiting roller (22); the rotating rod (332) is connected to a first driving member (35) for controlling the rotation angle of the rotating rod (332).

5. The positioning device of the paper-plastic composite capping machine according to claim 4, characterized in that: The first driving member (35) comprises a first gear (351), a second gear (352) and a first motor (353); the first gear (351) is coaxially fixed to the rotating rod (332); the second gear (352) is rotatably mounted on the bracket (1) and meshes with the first gear (351); the first motor (353) is mounted on the bracket (1) and its output shaft is coaxially fixedly connected to the second gear (352).

6. The positioning device of the paper-plastic composite capping machine according to claim 1, characterized in that: A guide ring (23) is coaxially arranged on the limiting roller (22); one end of the guide ring (23) is flat and fixed to a groove wall of the limiting groove (221) arranged along the axial direction of the limiting roller (22); the other end of the guide ring (23) is hemispherical.

7. The positioning device of the paper-plastic composite capping machine according to claim 1, characterized in that: A moving part (24) is connected between the limiting frame (21) and the bracket (1), and the moving part (24) comprises a moving slide (241) and a bidirectional lead screw (242). The moving slide (241) is mounted on the bracket (1), and the bidirectional lead screw (242) is rotatably mounted on the moving slide (241) and radially arranged along the moving track of the kraft paper. The limiting frame (21) is threadedly connected to the bidirectional lead screw (242) along the axial direction of the bidirectional lead screw (242), and the moving slide (241) is slidably connected to the limiting frame (21).

8. The positioning device of the paper-plastic composite capping machine according to claim 7, characterized in that: The bidirectional lead screw (242) is connected to a second driving member (25) for controlling the rotation of the bidirectional lead screw (242); the second driving member (25) comprises a second motor (251) and a distance sensor (252); the second motor (251) is mounted on the moving slide plate (241) and the output shaft is coaxially connected to the bidirectional lead screw (242); the distance sensor (252) is mounted on the groove wall of the limiting groove (221); the distance sensors (252) on the two limiting rollers (22) are radially arranged along the moving track of the kraft paper.

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