A printing device for paper-plastic composite bags

Abstract

This utility model relates to a paper-plastic composite bag printing device, including a printing table disposed at the upper end of a conveyor belt, and also including an adjustable paper bag box, a bag feeding assembly, and a positioning assembly. The adjustable paper bag box is disposed at the front end of the conveyor belt, and at least two side walls of the adjustable paper bag box are provided with adjustable position limiting plates. The bag feeding assembly is disposed at the lower end of the adjustable paper bag box and is used to feed the paper-plastic composite bags in the adjustable paper bag box one by one onto the conveyor belt. The positioning assembly is disposed on the conveyor belt and located between the adjustable paper bag box and the printing table, and is used to position and adjust the position of the paper-plastic composite bags fed by the bag feeding assembly. This utility model can be flexibly adjusted according to different specifications of paper-plastic composite bags, ensuring accurate placement and positioning of the paper-plastic composite bags during the printing process, improving printing quality and production efficiency.

Description

Technical Field

[0001] This utility model relates to the field of packaging bag printing technology, and in particular to a paper-plastic composite bag printing device. Background Technology

[0002] Paper-plastic composite bags are made of plastic and kraft paper. The plastic layer is usually made of flat woven fabric with polypropylene (PP) or polyethylene (PE) as the base material, while the kraft paper is made of refined composite kraft paper, which has the characteristics of high strength, good water resistance and beautiful appearance. When customizing paper-plastic composite bags, printing is required on the paper-plastic composite bags according to the customer's requirements. For example, CN216330746U discloses a paper-plastic composite bag printing device. A paper bag box is set in the paper feeding direction of the screen printing machine printing table. A stack of paper-plastic packaging bags is filled in the paper bag box. By reciprocating push of the cylinder, the paper-plastic packaging bags in the paper bag box are fed out one by one using the unidirectional paper feeding characteristic of the bag feeding component. Compared with the traditional manual operation of placing paper-plastic packaging bags, the operation is simple, the paper feeding is stable, and it can adapt to paper-plastic packaging bags of different thicknesses. However, paper-plastic composite bags have different specifications according to customer requirements, but this device can only place paper-plastic composite bags of the same specification for printing. Placing paper-plastic composite bags of larger or smaller specifications in the paper bag box, if the placement position is incorrect, will lead to subsequent printing defects and affect the printing quality.

[0003] Therefore, it is necessary to develop a paper-plastic composite bag printing device to address the above-mentioned shortcomings. Utility Model Content

[0004] The purpose of this invention is to provide a paper-plastic composite bag printing device that can be flexibly adjusted according to different specifications of paper-plastic composite bags, ensuring accurate placement and positioning of the paper-plastic composite bags during the printing process, thereby improving printing quality and production efficiency.

[0005] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0006] This utility model discloses a paper-plastic composite bag printing device, including a printing table disposed at the upper end of a conveyor belt, and further including an adjustable paper bag box, a bag feeding assembly, and a positioning assembly. The adjustable paper bag box is disposed at the front end of the conveyor belt, and at least two side walls of the adjustable paper bag box are provided with adjustable position limiting plates. The bag feeding assembly is disposed at the lower end of the adjustable paper bag box and is used to feed the paper-plastic composite bags in the adjustable paper bag box one by one onto the conveyor belt. The positioning assembly is disposed on the conveyor belt and located between the adjustable paper bag box and the printing table, and is used to position and adjust the position of the paper-plastic composite bags fed by the bag feeding assembly.

[0007] Preferably, the adjustable paper bag box includes a box body, which is fixedly installed at the front end of the conveyor belt. The bottom end of the box body is provided with a sliding groove, and the limiting plates on both sides are slidably installed in the sliding groove by sliders. The sliders and the limiting plates are integral structures. A bidirectional lead screw is rotatably installed in the sliding groove. The slider is provided with a threaded hole adapted to the bidirectional lead screw. The slider passes through the threaded hole and engages with the threaded sections at both ends of the bidirectional lead screw. One end of the bidirectional lead screw extends out of the box body and is fixedly installed on the output shaft of a first motor. The first motor drives the bidirectional lead screw to rotate, so that the limiting plates on both sides move closer or further apart to accommodate paper-plastic composite bags of different widths. Fixed plates are provided on the front and rear sides of the box body. A gap is provided between the fixed plate near the conveyor belt outlet and the conveyor belt to facilitate the passage of paper-plastic composite bags.

[0008] Preferably, the bag feeding assembly includes two sets of cylinders, three sets of parallel transmission rods, and one-way paper feeding wheels. The two sets of cylinders are respectively fixedly installed on both sides of the fixed plate of the adjustable paper bag box. The output end of the cylinder is fixed on the connecting rod. The two ends of the three sets of transmission rods are rotatably installed on the connecting rod. Each set of transmission rods is rotatably installed with multiple one-way paper feeding wheels through bearings. The one-way paper feeding wheels of the three sets of transmission rods are staggered. The one-way paper feeding wheels contact the bottom of the paper-plastic composite bags in the adjustable paper bag box. Through the reciprocating push of the cylinders, the paper-plastic composite bags are fed out one by one onto the conveyor belt.

[0009] Preferably, the positioning assembly includes a positioning plate and an electric telescopic rod. The positioning plates are symmetrically arranged on both sides of the conveyor belt. The back of the positioning plates is fixedly mounted on the telescopic end of the electric telescopic rod. The electric telescopic rod is fixed on both sides of the conveyor belt by a bracket. The electric telescopic rod drives the positioning plates to move closer or further apart to adjust the lateral position of the paper-plastic composite bag. A pre-pressure roller is provided at the rear end of the positioning plate. The distance between the pre-pressure roller and the conveyor belt is adjusted by an adjustment assembly to accommodate paper-plastic composite bags of different thicknesses.

[0010] Preferably, the front end of the positioning plate is horizontally positioned near the printing table, and the rear end is inclined near the adjustable paper bag box, with the opening facing away from the center of the conveyor belt.

[0011] Preferably, the adjustment assembly includes a slide and a fixed seat fixed on both sides of the conveyor belt frame. The slide is disposed inside the fixed seat and is slidably connected to the fixed seat in the vertical direction. A bolt is provided at the upper end of the slide, which passes through the fixed seat and is threadedly connected to the fixed seat. The two ends of the preload roller are rotatably mounted on the slide via bearings. By rotating the bolt, the position of the slide within the fixed seat can be adjusted, thereby adjusting the distance between the preload roller and the conveyor belt.

[0012] Preferably, the conveyor belt is provided with a support plate on the lower side of the feeding section.

[0013] Preferably, the bottom surface of the box is flush with the upper surface of the conveyor belt.

[0014] Compared with the prior art, the beneficial technical effects of this utility model are as follows:

[0015] This utility model of paper-plastic composite bag printing device, through the design of adjustable paper bag boxes and positioning components, can flexibly adjust to paper-plastic composite bags of different specifications, ensuring accurate placement and positioning of the bags during the printing process. This avoids printing defects caused by inconsistencies in specifications and greatly improves printing quality. The device can adapt to paper-plastic composite bags of different widths and thicknesses, improving production flexibility and adaptability, and meeting diverse customer customization needs. The bag feeding component enables automatic, one-by-one feeding of paper-plastic composite bags, while the positioning component quickly and accurately positions the bags, reducing manual operation time and errors, and improving overall production efficiency. The support plate under the conveyor belt feed section supports the bag body, preventing jamming due to gravity during feeding and printing, which would affect the printing effect. Attached Figure Description

[0016] The present invention will be further described below with reference to the accompanying drawings.

[0017] Figure 1 This is a three-dimensional structural diagram of the paper-plastic composite bag printing device of this utility model;

[0018] Figure 2 This is a schematic diagram of the main structure of the paper-plastic composite bag printing device of this utility model;

[0019] Figure 3 This is a top view of the paper-plastic composite bag printing device of this utility model.

[0020] Explanation of reference numerals in the attached drawings: 1. Printing table; 2. Conveyor belt; 3. Adjustable paper bag box; 301. Limiting plate; 302. Box body; 303. Slide groove; 304. Slider; 305. Two-way lead screw; 306. First motor; 307. Fixing plate; 4. Bag feeding assembly; 401. Cylinder; 402. Transmission rod; 403. One-way paper feeding wheel; 404. Connecting rod; 5. Positioning assembly; 501. Positioning plate; 502. Electric telescopic rod; 503. Bracket; 504. Pre-pressure roller; 6. Adjustment assembly; 601. Slide seat; 602. Fixing seat; 603. Bolt; 7. Support plate. Detailed Implementation

[0021] The core of this utility model is to provide a paper-plastic composite bag printing device that can be flexibly adjusted according to different specifications of paper-plastic composite bags, ensuring the accurate placement and positioning of paper-plastic composite bags during the printing process, thereby improving printing quality and production efficiency.

[0022] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present utility model, and not all of them. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0023] In the description of this utility model, it should be understood that the terms "upper", "lower", "front", "rear", "left", "right", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this utility model 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. Therefore, they should not be construed as limitations on this utility model.

[0024] Refer to the attached diagram. Figure 1 This is a schematic diagram of the main structure of the paper-plastic composite bag printing device of this utility model; Figure 2 This is a top view structural schematic diagram of the paper-plastic composite bag printing device of this utility model; Figure 3 This is a schematic diagram of the left side of the paper-plastic composite bag printing device of this utility model.

[0025] In one specific implementation, such as Figures 1-3As shown, a paper-plastic composite bag printing device includes a printing table 1, which is positioned at the upper end of a conveyor belt 2. Printing is performed via the conveyor belt 2, increasing the printing speed. It also includes an adjustable paper bag box 3, a bag feeding assembly 4, and a positioning assembly 5. The adjustable paper bag box 3 is positioned at the front end of the conveyor belt 2, and at least two side walls of the adjustable paper bag box 3 are provided with adjustable positioning plates 301; by adjusting the distance of the positioning plates 301, it can accommodate the placement of paper-plastic composite bags of different sizes. The bag feeding assembly 4 is positioned at the lower end of the adjustable paper bag box 3, and is used to feed the paper-plastic composite bags one by one from the adjustable paper bag box 3 onto the conveyor belt 2. The positioning assembly 5 is positioned on the conveyor belt 2 and located between the adjustable paper bag box 3 and the printing table 1, and is used to position and adjust the position of the paper-plastic composite bags fed out by the bag feeding assembly 4.

[0026] In one specific implementation, such as Figures 1-3 As shown, the adjustable paper bag box 3 includes a box body 302, which is fixedly installed at the front end of the conveyor belt 2. A groove 303 is provided at the bottom of the box body 302. Limiting plates 301 on both sides are slidably installed in the groove 303 via sliders 304, which are integral with the limiting plates 301. A bidirectional lead screw 305 is rotatably installed in the groove 303. The slider 304 has threaded holes adapted to the bidirectional lead screw 305, and the slider 304 passes through the threaded holes and engages with the threaded sections at both ends of the bidirectional lead screw 305. One end of the bidirectional lead screw 305 extends out of the box body 302 and is fixedly installed on the output shaft of a first motor 306. The first motor 306 drives the bidirectional lead screw 305 to rotate, causing the limiting plates 301 on both sides to move closer or further apart, accommodating paper-plastic composite bags of different widths. The front and rear sides of the box 302 are provided with fixing plates 307. The fixing plate 307 near the outlet of the conveyor belt 2 is provided with a gap between it and the conveyor belt 2 to facilitate the passage of paper-plastic composite bags. According to the width specifications of the paper-plastic composite bags to be printed, the first motor 306 is started to adjust the distance between the limiting plates 301 on both sides of the adjustable paper bag box 3.

[0027] In one specific implementation, such as Figures 1-3As shown, the bag feeding assembly 4 includes two sets of cylinders 401, three sets of parallel transmission rods 402, and one-way paper feeding rollers 403. The two sets of cylinders 401 are fixedly installed on both sides of the fixed plate 307 of the adjustable paper bag box 3. The output ends of the cylinders 401 are fixed to the connecting rod 404. The two ends of the three sets of transmission rods 402 are rotatably installed on the connecting rod 404. Multiple one-way paper feeding rollers 403 are rotatably installed on each set of transmission rods 402 via bearings. The one-way paper feeding rollers 403 are mounted on the transmission rods 402. The one-way paper feeding rollers are arranged in a staggered pattern on the transmission rods, with a spacing of 5-10mm between adjacent rollers, ensuring that only a single bag is contacted each time. The one-way paper feeding rollers 403 contact the bottom of the paper-plastic composite bags inside the adjustable paper bag box 3. Through the reciprocating push of the cylinders 401, the paper-plastic composite bags are fed one by one onto the conveyor belt 2. The cylinders 401 here are all of the same model and are connected to the control valves. Each side is equipped with a regulating valve to control the air intake of each cylinder, ensuring consistency between the two sides. The unidirectional feed roller uses a unidirectional bearing structure to transport the paper-plastic composite bag when rotating in the forward direction and automatically locks when rotating in the reverse direction to prevent backflow. The reverse locking function prevents the paper-plastic composite bag from shifting position. The unidirectional feed roller surface is typically made of a high-friction material such as rubber, silicone, or polyurethane, with horizontal lines, diagonal lines, or raised dots to increase the contact friction with the paper-plastic composite bag (static friction coefficient ≥ 0.8) and reduce slippage.

[0028] In one specific implementation, such as Figures 1-3 As shown, the positioning component 5 includes a positioning plate 501 and an electric telescopic rod 502. The positioning plates 501 are symmetrically arranged on both sides of the conveyor belt 2, and their backs are fixedly mounted on the telescopic ends of the electric telescopic rod 502. The electric telescopic rod 502 is fixed to both sides of the conveyor belt 2 by a bracket 503. The electric telescopic rod 502 drives the positioning plates 501 to move closer or further apart, thereby adjusting the lateral position of the paper-plastic composite bag. A pre-pressure roller 504 is provided at the rear end of the positioning plate 501. The distance between the pre-pressure roller 504 and the conveyor belt 2 is adjusted by an adjusting component 6 to accommodate paper-plastic composite bags of different thicknesses. The paper-plastic composite bag moves on the conveyor belt 2 and enters the area of ​​the positioning component 5. The electric telescopic rod 502 drives the positioning plate 501 to adjust the lateral position of the paper-plastic composite bag, and the pre-pressure roller 504 adapts to the thickness of the paper-plastic composite bag and maintains its stability. Finally, the paper-plastic composite bag is conveyed to the printing table 1 for printing.

[0029] In one specific implementation, such as Figures 1-3 As shown, the front end of the positioning plate 501, near the printing table 1, is horizontally positioned, while the rear end, near the adjustable paper bag box 3, is inclined, with its opening facing away from the center of the conveyor belt 2. The angle between the inclined portion and the horizontal direction is 5° to 10°. This shape facilitates the smooth entry of the paper-plastic composite bag into the positioning plates 501, while ensuring the stability of the paper-plastic composite bag during the positioning process.

[0030] In one specific implementation, such as Figures 1-3 As shown, the adjustment assembly 6 includes a slide 601 and a fixed seat 602 fixed on both sides of the frame of the conveyor belt 2. The slide 601 is disposed inside the fixed seat 602, and the slide 601 and the fixed seat 602 are slidably connected in the vertical direction. A bolt 603 is provided at the upper end of the slide 601, which passes through the fixed seat 602 and is threadedly connected to the fixed seat 602. The two ends of the pre-pressure roller 504 are rotatably mounted on the slide 601 through bearings. By rotating the bolt 603, the position of the slide 601 within the fixed seat 602 can be adjusted, thereby adjusting the distance between the pre-pressure roller 504 and the conveyor belt 2. The pre-pressure roller 504, by adjusting the distance with the conveyor belt 2, adapts to paper-plastic composite bags of different thicknesses, improving printing quality. The adjustment assembly allows the distance between the pre-pressure roller and the conveyor belt to be adjusted within the range of 0.5-5mm, suitable for paper-plastic composite bags with a thickness of 0.1-3mm.

[0031] In one specific implementation, such as Figures 1-3 As shown, a support plate 7 is located below the feeding section of the conveyor belt 2. This support plate 7 supports the paper-plastic composite bags fed through the conveyor belt 2, preventing the bags from sagging due to gravity during feeding and printing, which would affect the stability of the feeding and printing processes. The upper surface of the support plate 7 has a smooth coating to reduce friction with the conveyor belt 2.

[0032] In one specific implementation, such as Figures 1-3 As shown, the bottom surface of the inner wall of the housing 302 is flush with the upper surface of the conveyor belt 2. This ensures a smooth transition when the paper-plastic composite bag is fed from the adjustable paper bag box 3 to the conveyor belt 2, avoiding jamming or misalignment of the paper-plastic composite bag due to height differences, and further improving the accuracy of bag feeding and positioning. The bottom surface of the inner wall of the housing 302 has a smooth layer to reduce friction between the paper-plastic composite bag and the bottom surface of the housing 302.

[0033] The operation process of this paper-plastic composite bag printing device is as follows: The paper-plastic composite bags to be printed are neatly stacked in the adjustable paper bag box 3. According to the width specifications of the paper-plastic composite bags, the first motor 306 is started. The first motor 306 drives the bidirectional lead screw 305 to rotate. Since the slider 304 is threadedly connected to the bidirectional lead screw 305 and the slider 304 and the limiting plate 301 are an integral structure, the rotation of the bidirectional lead screw 305 causes the limiting plates 301 on both sides to move closer or further apart in the slide groove 303, thereby adjusting the distance between the limiting plates 301 to accommodate paper-plastic composite bags of different width specifications and ensure that the paper-plastic composite bags are placed neatly in the paper bag box. The cylinder 401 is fixedly installed on the frame below the adjustable paper bag box 3. The output end of the cylinder 401 is connected to the transmission rod 402. Multiple unidirectional paper feeding wheels 403 are rotatably installed on the transmission rod 402, and the unidirectional paper feeding wheels 403 contact the bottom of the paper-plastic composite bags. The cylinder 401 reciprocates, utilizing the unidirectional rotation characteristic of the paper feeding roller 403 to feed the paper-plastic composite bags one by one from the adjustable paper bag box 3 onto the conveyor belt 2. The fed paper-plastic composite bags move forward on the conveyor belt 2 and enter the positioning component 5 area. The electric telescopic rod 502 is fixed to both sides of the conveyor belt 2 by the bracket 503. The positioning plates 501 are symmetrically arranged on both sides of the conveyor belt 2, with their backs fixed to the telescopic ends of the electric telescopic rod 502. The electric telescopic rod 502 drives the positioning plates 501 to move closer or further apart, adjusting the lateral position of the paper-plastic composite bags. Simultaneously, by rotating the bolt 603 in the adjusting assembly 6, the position of the slide 601 within the fixed seat 602 can be adjusted because the slide 601 and the fixed seat 602 are slidably connected in the vertical direction and the bolt 603 is threadedly connected to the fixed seat 602. This adjusts the distance between the pre-pressure roller 504 and the conveyor belt 2 to accommodate paper-plastic composite bags of different thicknesses, ensuring that the paper-plastic composite bags maintain accurate positioning and stable posture on the conveyor belt 2. After positioning and adjustment, the paper-plastic composite bags are conveyed to the printing table 1 by the conveyor belt 2 for printing.

[0034] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For the apparatus disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the description is relatively simple; relevant parts can be referred to the method section.

[0035] The embodiments described above are merely preferred embodiments of the present utility model and are not intended to limit the scope of the present utility model. Various modifications and improvements made to the technical solutions of the present utility model by those skilled in the art without departing from the spirit of the present utility model should fall within the protection scope defined by the claims of the present utility model.

Claims

1. A paper-plastic composite bag printing device, comprising a printing table (1), wherein the printing table (1) is disposed at the upper end of a conveyor belt (2), characterized in that: It also includes an adjustable paper bag box (3), a bag feeding assembly (4), and a positioning assembly (5); the adjustable paper bag box (3) is located at the front end of the conveyor belt (2), and at least two side walls of the adjustable paper bag box (3) are provided with adjustable position limiting plates (301); the bag feeding assembly (4) is located at the lower end of the adjustable paper bag box (3) and is used to feed the paper-plastic composite bags in the adjustable paper bag box (3) one by one onto the conveyor belt (2); the positioning assembly (5) is located on the conveyor belt (2) and between the adjustable paper bag box (3) and the printing table (1) and is used to position and adjust the position of the paper-plastic composite bags fed out by the bag feeding assembly (4).

2. The paper-plastic composite bag printing apparatus according to claim 1, characterized in that: The adjustable paper bag box (3) includes a box body (302), which is fixedly installed at the front end of the conveyor belt (2). The bottom end of the box body (302) is provided with a slide groove (303). The limiting plates (301) on both sides are slidably installed in the slide groove (303) by sliders (304). The sliders (304) and the limiting plates (301) are integral structures. A bidirectional lead screw (305) is rotatably installed in the slide groove (303). The slider (304) is provided with a threaded hole adapted to the bidirectional lead screw (305). The slider (304) passes through the threaded hole and... The two ends of the bidirectional lead screw (305) are engaged with each other. One end of the bidirectional lead screw (305) extends out of the housing (302) and is fixedly installed on the output shaft of the first motor (306). The first motor (306) drives the bidirectional lead screw (305) to rotate, so that the limiting plates (301) on both sides move closer or further apart to accommodate paper-plastic composite bags of different widths. The front and rear sides of the housing (302) are provided with fixing plates (307). The fixing plate (307) near the outlet of the conveyor belt (2) is provided with a gap between it and the conveyor belt (2) to facilitate the passage of paper-plastic composite bags.

3. The paper-plastic composite bag printing apparatus according to claim 2, characterized in that: The bag feeding assembly (4) includes two sets of cylinders (401), three sets of parallel transmission rods (402), and one-way paper feeding wheels (403). The two sets of cylinders (401) are respectively fixedly installed on both sides of the fixed plate (307) of the adjustable paper bag box (3). The output end of the cylinder (401) is fixed on the connecting rod (404). The two ends of the three sets of transmission rods (402) are rotatably installed on the connecting rod (404). Each set of transmission rods (402) is rotatably installed with multiple one-way paper feeding wheels (403) through bearings. The one-way paper feeding wheels (403) of the three sets of transmission rods (402) are staggered. The one-way paper feeding wheels (403) contact the bottom of the paper-plastic composite bag in the adjustable paper bag box (3). Through the reciprocating push of the cylinders (401), the paper-plastic composite bags are fed out one by one onto the conveyor belt (2).

4. The paper-plastic composite bag printing apparatus according to claim 1, characterized in that: The positioning component (5) includes a positioning plate (501) and an electric telescopic rod (502). The positioning plate (501) is symmetrically arranged on both sides of the conveyor belt (2). The back of the positioning plate (501) is fixedly installed on the telescopic end of the electric telescopic rod (502). The electric telescopic rod (502) is fixed on both sides of the conveyor belt (2) by a bracket (503). The electric telescopic rod (502) drives the positioning plate (501) to move closer or further away from each other to adjust the lateral position of the paper-plastic composite bag. The rear end of the positioning plate (501) is provided with a pre-pressure roller (504). The distance between the pre-pressure roller (504) and the conveyor belt (2) is adjusted by an adjustment component (6) to accommodate paper-plastic composite bags of different thicknesses.

5. The paper-plastic composite bag printing apparatus according to claim 4, characterized in that: The front end of the positioning plate (501) is horizontally positioned near the printing table (1), and the rear end is inclined near the adjustable paper bag box (3), with the opening facing away from the center of the conveyor belt (2).

6. The paper-plastic composite bag printing apparatus according to claim 5, characterized in that: The adjustment assembly (6) includes a slide (601) and a fixed seat (602) fixed on both sides of the frame of the conveyor belt (2). The slide (601) is disposed in the fixed seat (602). The slide (601) and the fixed seat (602) are slidably connected in the vertical direction. The upper end of the slide (601) is provided with a bolt (603). The bolt (603) passes through the fixed seat (602) and is threadedly connected to the fixed seat (602). The two ends of the preload roller (504) are rotatably mounted on the slide (601) through bearings. By rotating the bolt (603), the position of the slide (601) in the fixed seat (602) can be adjusted, thereby adjusting the distance between the preload roller (504) and the conveyor belt (2).

7. The paper-plastic composite bag printing apparatus according to claim 1, characterized in that: The conveyor belt (2) is provided with a support plate (7) on the lower side of the feeding section.

8. The paper-plastic composite bag printing apparatus according to claim 2, characterized in that: The bottom surface inside the box (302) is flush with the upper surface of the conveyor belt (2).

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