A mounting machine for implementing a blank area on a light permeable sheet

Abstract

This utility model discloses a laminating machine for creating a blank area on a translucent sheet, comprising a sheet laminating mechanism and an adhesive applicator. The sheet laminating mechanism includes a clamping conveyor roller and a continuous rotation drive that drives the clamping conveyor roller to rotate continuously while carrying the sheet. The adhesive applicator includes an adhesive applicator roller for applying adhesive to the sheet laminating surface and an intermittent adhesive applicator drive that drives the adhesive applicator roller to rotate intermittently. There is an adhesive applicator gap between the adhesive applicator roller and the clamping conveyor roller for the sheet to move. The adhesive applicator roller has a first state and a second state. In the first state, the adhesive applicator roller rotates and cooperates with the clamping conveyor roller to apply adhesive to the sheet laminating surface. In the second state, the linear velocity of the adhesive applicator roller is less than the linear velocity of the clamping conveyor roller and it remains in contact with the sheet laminating surface. The clamping conveyor roller drives the sheet to continue moving, so that a blank area is formed at the end of the sheet laminating surface. The glue-coating roller of this invention rotates at a variable speed. In the first state, the glue-coating roller applies glue to the sheet. In the second state, the glue-coating roller stops rotating or rotates at a speed lower than that of the clamping conveyor roller, allowing the sheet to continue moving and creating a blank area at the end of the sheet composite surface to avoid glue overflow at the end.

Description

Technical Field

[0001] This utility model relates to the field of sheet lamination, and in particular to a lamination machine for creating blank areas on translucent sheets. Background Technology

[0002] High-end card products such as translucent cards and miniature cards are widely used in the fields of collectibles, gifts, membership badges, and cultural and creative products. Due to their exquisite design and special materials, they have high artistic and market value. These cards are usually made by laminating a single-sided translucent sheet (such as PVC or PET) with a base cardboard, or by combining two layers of translucent sheets.

[0003] In the current manufacturing processes of high-end card products such as transparent cards and mini cards, existing lamination equipment typically uses an adhesive coating method to apply glue to the sheets, and then uses a composite roller to move the composite sheets upwards to achieve lamination. However, because the surface of the translucent sheets is smooth and transparent, if the glue coating thickness is insufficient, air bubbles can easily remain between the two layers of composite sheets, seriously affecting the product appearance and yield. To ensure uniform glue distribution and avoid air bubble formation, a thicker glue layer is often required in actual operation.

[0004] As the composite sheet moves upward, an excessively thick adhesive layer causes it to extend downwards, resulting in adhesive overflow mostly occurring at the tail end. This overflow not only contaminates the surface of the laminating roller but also contaminates materials processed subsequently. Due to the technical issues between the adhesive coating process and material characteristics, existing laminating equipment struggles to strike a balance between ensuring the adhesive layer thickness and preventing overflow, leading to the continued reliance on manual methods for laminating operations in this field. Summary of the Invention

[0005] This invention addresses the shortcomings of existing technologies by providing a laminating machine that creates a blank area for translucent sheets, preventing adhesive overflow from contaminating the composite roller surface during the lamination process.

[0006] To solve the above-mentioned technical problems, this utility model provides the following technical solution: a laminating machine for creating a blank area on translucent sheets, comprising a sheet laminating mechanism and an adhesive applicator; the sheet laminating mechanism includes a clamping conveyor roller and a continuous rotation drive that drives the clamping conveyor roller to continuously rotate while carrying the sheet; the adhesive applicator includes an adhesive applicator roller for applying adhesive to the sheet laminating surface and an intermittent adhesive applicator drive that drives the adhesive applicator roller to rotate intermittently, wherein there is an adhesive applicator gap between the adhesive applicator roller and the clamping conveyor roller for sheet movement, and the adhesive applicator roller has a first state and a second state, wherein the adhesive applicator roller in the first state rotates and cooperates with the clamping conveyor roller to apply adhesive to the sheet laminating surface; the linear velocity of the adhesive applicator roller in the second state is less than the linear velocity of the clamping conveyor roller and remains in contact with the sheet laminating surface, and the clamping conveyor roller drives the sheet to continue moving, so that a blank area is formed at the end of the sheet laminating surface.

[0007] The glue-applying roller of this invention rotates at a variable speed. In the first state, the glue-applying roller first applies glue to the composite surface of the sheet. Then, the glue-applying roller enters the second state, where it stops rotating or its rotation speed is lower than that of the clamping conveyor roller. While the glue-applying roller rotates again, the clamping conveyor roller continues to rotate, allowing the sheet to continue moving. Because the glue-applying roller rotates at a low speed or stops rotating, there is little or no glue at the contact position at its tail, forming a blank area at the end of the composite surface of the sheet. Therefore, during the lamination process, any excess glue can extend to the blank area at the tail, avoiding glue overflow at the tail, reducing pollution, and ensuring the yield of the finished product.

[0008] Preferably, the adhesive application drive can drive the adhesive application roller to rotate intermittently. This further reduces the amount of adhesive in the tail blank area, thereby avoiding contamination of the roller surface and improving the yield.

[0009] Preferably, the gluing mechanism further includes two glue-removing components. The coating roller has a contact roller surface, which, after being de-gummed by the glue-removing components, contacts the sheet material composite surface conveyed by the clamping conveyor roller. The two glue-removing components are arranged at intervals along the axis of the coating roller and are both located on the same side of the coating roller. The glue-removing components abut against the contact roller surface to form two glue-free blank areas corresponding to each other. The contact roller surface between the two glue-free blank areas is the glue-applying area. The glue-free blank areas allow the glue layer in the glue-applying area to extend to the left and right sides during the sheet material composite process, preventing excess glue from overflowing from the sides and further preventing the roller surface from being contaminated by glue.

[0010] Based on the presence of a glue-free blank area and a glue-applied area, the glue-applied area of ​​the coating roller allows the sheet composite surface to form an adhesive area accordingly, and the glue-free blank area of ​​the coating roller allows the left and right sides of the sheet composite surface to form lateral blank areas respectively. The lateral blank areas provide space for the adhesive layer of the adhesive area to extend during the sheet composite process.

[0011] Preferably, the coating roller includes a first hard roller and a first adhesive coating layer. The first hard roller ensures that the coating gap remains constant during the coating process. The first adhesive coating layer is disposed on the outer circumferential surface of the first hard roller and ensures stable coating. The first hard roller can prevent expansion caused by long-term contact with adhesive, ensuring the service life of the coating roller and further ensuring that the coating gap does not change. In addition, the first adhesive coating layer can ensure adhesive adhesion, thereby ensuring coating quality.

[0012] Preferably, the gluing mechanism further includes a gluing roller and a transfer roller, with the transfer roller positioned between the coating roller and the gluing roller. Therefore, the gluing roller includes a second hard roller and a second gluing coating layer, the second gluing coating layer being disposed on the outer circumferential surface of the second hard roller. The transfer roller includes a third hard roller and a third gluing coating layer, the third gluing coating layer being disposed on the outer circumferential surface of the third hard roller. This ensures the quantitative and uniform transfer of the glue.

[0013] Preferably, a glue tray is provided below the glue roller. The glue tray includes a box body and a cover body. The cover body is provided with an opening for the glue roller to pass through, and the glue roller is placed inside the box body through the opening. The cover body can reduce the opening of the glue tray and slow down the evaporation rate.

[0014] Preferably, the frame is equipped with a guide rod, and the adhesive removal component is adjustablely mounted on the guide rod along the axial direction of the coating roller. The guide rod is arranged parallel to the coating roller, and the distance between the adhesive removal components can be adjusted according to the sheet material of different specifications.

[0015] In addition to the guide rod, the adhesive removal component also includes a movable base. The adhesive removal part is connected to the movable base via an adjusting screw, which drives the adhesive removal component to move back and forth relative to the movable base. This back-and-forth movement of the adhesive removal component facilitates equipment adjustment and ensures effective adhesive removal.

[0016] Preferably, the clamping conveyor roller has gripper bars and a straight clamping groove for accommodating the front end of the sheet. The straight clamping groove includes a clamping surface, which is lower than the composite roller surface of the clamping conveyor roller. The gripper bars cooperate with the clamping surface of the straight clamping groove to clamp the sheet. The cooperation between the gripper bars and the clamping surface causes the end of the sheet to bend inward into the straight clamping groove, creating a non-adhesive linear blank area at the front edge of the composite surface of the sheet. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the structure of this utility model.

[0018] Figure 2 This is a perspective view of the present invention.

[0019] Figure 3 This is a schematic diagram of the adhesive application mechanism of this utility model.

[0020] Figure 4 This is a schematic diagram of the structure of the material clamping conveyor roller of this utility model.

[0021] Figure 5 This is a schematic diagram of the blank area of ​​the sheet material of this utility model.

[0022] The names of the body parts referred to by the numbers in the above attached diagrams are as follows: The components include: 1. Clamping conveyor roller; 2. Glue coating roller; 21. Contact roller surface; 211. Glue-free blank area; 212. Glue-applying area; 3. Glue removal component; 4. Glue application roller; 5. Glue transfer roller; 6. Glue tray; 61. Box body; 62. Cover body; 63. Opening; 7. Guide rod; 8. Moving seat; 9. Adjusting screw; 10. Clamping straight long groove; 11. Paper gripper bar; 12. Frame; 13. Glue-coated sheet; 131. Tail blank area; 132. Side blank area; 133. Beginning linear blank area; 134. Bonding area. Detailed Implementation

[0023] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments.

[0024] See Figure 1 A laminating machine for creating blank areas on translucent sheets includes a sheet laminating mechanism and an adhesive applicator. The sheet laminating mechanism includes a clamping conveyor roller 1, which is connected to a continuous rotary drive that drives the sheet to rotate continuously. The sheet laminating mechanism also includes a composite clamping roller. The clamping conveyor roller 1 and the composite clamping roller rotate opposite each other, and a laminating gap exists between them for the sheet to pass through. The two rollers work together to achieve lamination between the sheets. The surface where the sheet clamped by the clamping conveyor roller 1 is laminated with another sheet is the laminated surface. The structures of the clamping conveyor roller 1 and the composite clamping roller can utilize existing technology. The gluing mechanism includes a gluing roller 2 for applying glue to the sheet composite surface and a gluing drive component for driving the gluing roller 2 to rotate at a variable speed. The gluing roller 2 is arranged parallel to the clamping conveyor roller 1. The gluing roller 2 is provided with a gluing gap between itself and the clamping conveyor roller 1 for the sheet to move. The gluing roller 2 has a first state and a second state. In the first state, the gluing roller 2 rotates and cooperates with the clamping conveyor roller 1 to apply glue to the sheet composite surface. In the second state, the linear speed of the gluing roller 2 is less than the linear speed of the clamping conveyor roller 1 and it remains in contact with the sheet composite surface. The clamping conveyor roller 1 drives the sheet to continue moving, so that the end of the sheet composite surface forms a tail blank area 131. After lamination, the blank area can be cut. The glue-applying drive unit can drive the glue-applying roller to rotate at a variable speed. When the sheet is coated with glue to the end, the glue-applying drive unit drives the glue-applying roller to reduce its speed, and its speed is lower than that of the clamping conveyor roller 1. This prevents the glue-applying roller from having enough time to accurately and continuously transfer the glue onto the sheet, thereby reducing the glue transfer rate and forming a blank area with very little glue at the end of the sheet. Alternatively, the glue-applying drive unit can drive the glue-applying roller 2 to rotate intermittently. When the sheet is coated with glue to the end, the glue-applying roller stops rotating, forming a blank area without glue at the end of the sheet. The blank area 131 at the end can extend the excess glue while ensuring sufficient glue, thereby avoiding glue overflow and contamination of the roller surface of the clamping conveyor roller 1. This eliminates the need for frequent machine stops for glue removal, improving work efficiency and yield.

[0025] See Figure 2 and Figure 3 To prevent glue from overflowing from the side of the sheet composite surface, the gluing mechanism also includes two glue-removing components 3. The coating roller 2 has a contact roller surface 21. The contact roller surface 21 is de-glued by the glue-removing components 3 before contacting the sheet composite surface conveyed by the clamping conveyor roller 1. The two glue-removing components 3 are arranged at intervals along the axis of the coating roller 2 and are both located on the same side of the coating roller 2. The glue-removing components 3 abut against the contact roller surface 21 to form two glue-free blank areas 211 on the contact roller surface 21. The two glue-free blank areas are spaced apart along the axis of the coating roller 2. The glue-free blank area 211 refers to the area where there is only a small amount of glue after the glue-removing components 3 scrape the glue off the contact roller surface 21. The glue-free component 3 can be a scraper or an adhesive-backed rubber blanket. The contact roller surface 21 between the two glue-free blank areas 211 is the glue application area 212 (see [link]). Figure 3 (The dotted lines represent the virtual division of the glue-free blank area 211 and the glue-applied area 212 for ease of understanding.) The glue-applied area 212 of the glue roller 2 allows the sheet composite surface to form an adhesive area 134. The glue-free blank area 211 of the glue roller 2 allows the left and right sides of the sheet composite surface to form lateral blank areas 132 respectively. The size of the lateral blank areas can be adjusted by changing the contact area between the glue removal component 3 and the contact roller surface 21. The lateral blank areas 132 allow the adhesive layer of the adhesive area 134 to extend during the sheet composite process. Excess adhesive can extend to the lateral blank areas 132 and the tail blank area 131 to further avoid glue overflow and ensure the yield rate.

[0026] In existing technologies, the coating roller 2 typically consists of a metal core and a double layer of rubber. The rubber layer, in prolonged contact with the adhesive, expands, altering the coating gap and affecting the amount of adhesive applied, thus reducing yield. This necessitates frequent adjustments. To prevent changes in the coating gap during production, the coating roller 2 includes a first hard roller and a first adhesive coating layer. The first hard roller ensures the coating gap remains constant during application. The first adhesive coating layer is disposed on the outer circumferential surface of the first hard roller, which is made of carbon steel or stainless steel. The first adhesive coating layer covers the outer surface of the first hard roller, forming a contact surface. This first adhesive coating layer ensures stable adhesive application by increasing the friction of the first hard roller. The first hard roller also prevents expansion caused by prolonged immersion, thus ensuring a constant coating gap and maintaining a high yield.

[0027] See Figure 1 and Figure 3To improve the stability of the gluing roller 4 and the transfer roller 5, the gluing mechanism further includes a gluing roller 4 and a transfer roller 5, with the transfer roller 5 positioned between the coating roller 2 and the gluing roller 4. Therefore, the gluing roller 4 includes a second hard roller and a second gluing coating, the second gluing coating being disposed on the outer circumferential surface of the second hard roller; the transfer roller 5 includes a third hard roller and a third gluing coating, the third gluing coating being disposed on the outer circumferential surface of the third hard roller. Both the transfer roller 5 and the gluing roller 4 are made of hard roller material and have an outer surface covered with a gluing coating to ensure quantitative and uniform transfer of the glue.

[0028] See Figure 3 To reduce the contact between the glue and air and slow down its evaporation, a glue tray 6 is provided below the glue roller 4. The glue tray 6 includes a box body 61 and a cover body 62. The box body 61 and the cover body 62 can be integrated or separate. The cover body 62 is provided with an opening 63 for the glue roller 4 to pass through. The glue roller 4 is partially placed inside the box body 61 through the opening 63. The box body 61 stores glue, and the glue roller 4 is partially immersed in the glue. The cover body 62 covers the box body 61, thereby reducing the contact between the glue and air.

[0029] To accommodate sheets of different specifications, the frame 12 is equipped with a guide rod 7, which is axially mounted on the frame along the coating roller 2. The adhesive removal component 3 is adjustablely mounted on the guide rod 7 along the axial direction of the coating roller 2. Various adjustment methods are available for the adhesive removal component 3; see [link to relevant documentation]. Figure 3 In this embodiment, the adhesive removal component 3 also includes a movable seat 8, which can be clamped onto the guide rod 7 and fixed in position by a locking screw. Furthermore, to adjust the front-to-back position of the adhesive removal part, the adhesive removal part is connected to the movable seat 8 via an adjusting screw 9. The adjusting screw 9 drives the adhesive removal component 3 to move back and forth relative to the movable seat 8. The adjusting screw 9 is threadedly connected to the movable seat 8; rotating the adjusting screw 9 drives the adhesive removal component 3 to move back and forth, ensuring the adhesive removal effect of the adhesive removal component 3.

[0030] See Figure 4 In the prior art, the gripper spacing of the paper gripper bar 11 is such that during the lamination process, the adhesive layer may overflow between the grippers, contaminating the glue roller. To avoid the adhesive layer overflowing from the front end of the sheet, the clamping conveyor roller 1 has a paper gripper bar 11 and a clamping straight groove 10 for accommodating the front end of the sheet. The clamping straight groove 10 is arranged along the axial direction of the clamping conveyor roller 1 and can accommodate the front edge of the sheet. The clamping straight groove 10 includes a clamping surface, which is lower than the lamination roller surface of the clamping conveyor roller 1. The paper gripper bar 11 and the clamping surface of the clamping straight groove 10 cooperate to clamp the sheet. The paper gripper bar 11 presses the front end of the sheet onto the clamping surface, making the front edge of the sheet concave. The glue roller 2 does not contact the front end of the sheet, thereby creating a non-adhesive linear blank area 133 at the front edge of the laminated sheet surface.

[0031] Example 1 The gripper bar 11 of the clamping conveyor roller 1 picks up the sheet and transfers it to the coating roller 2 for coating. At this time, the intermittent coating drive drives the coating roller 2 to the first state. The contact roller surface 21 of the coating roller 2 first passes through the glue removal component 3. The two glue removal components 3 make the two sides of the contact roller surface 21 form a glue-free blank area 211. Then the contact roller surface 21 of the coating roller 2 contacts the composite surface of the sheet for coating. An adhesive area and a side blank area are formed on the composite surface of the sheet. When the sheet is about to be coated, the coating roller 2 switches to the second state and stops rotating. The contact roller surface 21 of the coating roller 2 has a small amount of glue or even no glue. The clamping conveyor roller 1 drives the sheet to continue moving. The tail of the composite surface of the sheet continues to contact the contact roller surface 21 with little or no glue, so that the end of the composite surface of the sheet forms a tail blank area 131.

[0032] The present invention creates a tail blank area 131 at the end of the sheet composite surface, which can greatly reduce glue overflow. On this basis, a side blank area 132 is added to further reduce glue overflow, ensuring the cleanliness of the roller surface of the clamping conveyor roller 1 and the cleanliness of the product.

[0033] Example 2 Based on Example 1, in order to further reduce glue overflow, after the first sheet passes through, the composite surface of the subsequent sheets first contacts the coating roller 2 in the second state to achieve a blank area at the beginning of the composite surface of the sheet. Then the coating roller 2 switches to the first state to apply glue to the sheet. When the sheet is about to be coated, the coating roller 2 switches to the second state again to achieve a blank area 131 at the end of the composite surface of the sheet. This solution can prevent glue from overflowing from all sides of the sheet and further improve the yield.

[0034] Example 3 Based on Example 1, in order to achieve a blank area at the beginning, a straight clamping groove 10 can be provided on the clamping conveyor roller 1. The paper gripper bar 11 presses the front end of the sheet onto the clamping surface of the straight clamping groove 10, so that the front edge of the sheet is concave, thereby creating a non-adhesive linear blank area 133 at the front edge of the sheet composite surface. When the sheet enters, it can directly contact the glue coating roller 2 in the first state. When the sheet is about to exit, the glue coating roller 2 switches to the second state, realizing a blank area 131 at the end of the sheet composite surface. This solution can prevent glue from overflowing from all sides of the sheet, improve production efficiency, and further improve the yield.

[0035] In the description of this invention, it should be understood that the terms "center," "length," "width," "thickness," "upper," "lower," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating orientation or positional relationships based on the orientation or positional relationships shown in the accompanying drawings, are only for the convenience of describing the invention and simplifying the description, and do 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 the invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined with "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0036] In summary, the above description is only a preferred embodiment of the present utility model. All equivalent changes and modifications made within the scope of the patent application of the present utility model shall fall within the scope of the patent of the present utility model.

Claims

1. A laminating machine for creating blank areas on translucent sheets, characterized in that: Includes sheet lamination mechanism and gluing mechanism; A sheet composite mechanism includes a clamping conveyor roller (1) and a continuous rotation drive that drives the roller to carry the sheet to rotate continuously. The gluing mechanism includes a gluing roller (2) for applying glue to the composite surface of the sheet material and a gluing drive component for driving the gluing roller (2) to rotate at a variable speed. There is a gluing gap between the coating roller (2) and the clamping conveyor roller (1) for moving the sheet material. The coating roller (2) has a first state and a second state. The first state of the coating roller (2) rotates and cooperates with the clamping conveyor roller (1) to coat the composite surface of the sheet material with glue; The linear velocity of the coating roller (2) in the second state is less than that of the clamping conveyor roller (1) and it remains in contact with the sheet composite surface. The clamping conveyor roller (1) drives the sheet to continue moving, so that the end of the sheet composite surface forms a tail blank area (131).

2. The laminating machine for creating blank areas on translucent sheets according to claim 1, characterized in that: The adhesive application drive can drive the adhesive application roller (2) to rotate intermittently.

3. The laminating machine for creating blank areas on translucent sheets according to claim 1, characterized in that: The gluing mechanism also includes two glue removal components (3). The coating roller (2) has a contact roller surface (21), which is de-adhesive by the de-adhesive component (3) and then comes into contact with the composite surface of the sheet material conveyed by the clamping conveyor roller (1); Two adhesive removal components (3) are arranged at intervals along the axis of the coating roller (2) and are both located on the same side of the coating roller (2). The adhesive removal components (3) abut against the contact roller surface (21) to form two adhesive-free blank areas (211) on the contact roller surface (21). The contact roller surface (21) between the two adhesive-free blank areas (211) is the adhesive application area (212).

4. The laminating machine for creating blank areas on translucent sheets according to claim 3, characterized in that: The adhesive area (212) of the coating roller can form an adhesive area (134) on the sheet composite surface. The adhesive-free blank area (211) of the coating roller can form a side blank area (132) on the left and right sides of the sheet composite surface. The side blank area (132) provides for the extension of the adhesive layer of the adhesive area (134) during the sheet composite process.

5. The laminating machine for creating blank areas on translucent sheets according to claim 1, characterized in that: The coating roller (2) includes a first hard roller and a first coating layer. The first hard roller is used to ensure that the coating gap remains unchanged during the coating process. The first coating layer is disposed on the outer peripheral surface of the first hard roller. The first coating layer is used to ensure that the coating roller can apply glue stably.

6. The laminating machine for creating blank areas on translucent sheets according to claim 1 or 5, characterized in that: The gluing mechanism further includes a gluing roller (4) and a transfer roller (5), wherein the transfer roller (5) is disposed between the coating roller (2) and the gluing roller (4); Therefore, the adhesive roller (4) includes a second hard roller and a second adhesive coating, wherein the second adhesive coating is disposed on the outer peripheral surface of the second hard roller; The transfer roller (5) includes a third hard roller and a third adhesive coating, the third adhesive coating being disposed on the outer peripheral surface of the third hard roller.

7. The laminating machine for creating blank areas on translucent sheets according to claim 6, characterized in that: Below the glue roller (4) is a glue tray (6), which includes a box body (61) and a cover body (62). The cover body (62) is provided with an opening (63) for the glue roller (4) to pass through, and the glue roller (4) is placed inside the box body (61) through the opening (63).

8. The laminating machine for creating blank areas on translucent sheets according to claim 3, characterized in that: The frame (12) is provided with a guide rod (7), and the glue removal component (3) can be adjusted and set on the guide rod (7) along the axial direction of the glue coating roller (2).

9. The laminating machine for creating blank areas on translucent sheets according to claim 8, characterized in that: The adhesive removal component (3) also includes a movable seat (8). The adhesive removal part is connected to the movable seat (8) via an adjusting screw (9). The adjusting screw (9) can drive the adhesive removal component (3) to move back and forth relative to the movable seat (8) for adjustment.

10. The laminating machine for creating blank areas on translucent sheets according to claim 1, characterized in that: The clamping conveyor roller (1) has a paper gripper bar (11) and a clamping straight groove (10) for accommodating the front end of the sheet. The clamping straight groove (10) includes a clamping surface, which is lower than the composite roller surface of the clamping conveyor roller (1). The paper gripper bar (11) and the clamping surface of the clamping straight groove (10) cooperate to clamp the sheet.

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