A conveying mechanism for milk box ink-jet printing
Patent Information
- Application Number
- CN202522254571.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-10-24
- Publication Date
- 2026-09-18
- Estimated Expiration
- 2035-10-24
AI Technical Summary
这种方式存在几个显著的弊端：首先，单一输送线的放料工位有限，限制了整体放料效率，成为生产效率的瓶颈；其次，人工放料的节奏不一，导致包装盒在输送带上间距不均，时而紧密堆积，时而间隔过大，这种不稳定的输送状态会严重影响后续喷码工位的识别与喷印质量，容易导致漏喷、喷码位置不准或字迹重叠等问题，需要频繁停机调整，降低了生产效率；此外，现有的输送线护栏多为固定式结构，无法适应不同尺寸包装盒的输送需求，更换产品规格时需停机调整甚至更换部件，费时费力
[0014] The beneficial effects of this utility model are as follows: In this utility model, milk cartons are placed manually or mechanically on the first and second conveyor belts respectively. The milk cartons are conveyed forward under the action of the first or second conveyor belt. The guardrails on both sides can effectively prevent the milk cartons from shifting or detaching from the first or second conveyor belt during the conveying process. When the milk cartons are conveyed to the end of the first or second conveyor belt, they enter the third conveyor belt from both sides of the beginning of the third conveyor belt under the guidance of the guardrails. Then, the third conveyor belt conveys the milk cartons to the inkjet printing device at the end to complete the inkjet printing operation. By setting two parallel first and second conveyor belts, milk cartons can be loaded from both sides at the same time, improving the loading efficiency. The guardrails can prevent the milk cartons from detaching from the first or second conveyor belt and guide the conveying direction of the milk cartons, ensuring that the milk cartons accurately enter the third conveyor belt and avoiding blockage or jamming. The overall structure is simple and easy to operate, which can effectively improve the conveying efficiency and stability of milk cartons before inkjet printing, thus making it suitable for batch inkjet printing and conveying operations of milk cartons.
Smart Images
Figure CN224766327U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of packaging box conveying technology, and in particular to a conveying mechanism for inkjet printing on milk cartons. Background Technology
[0002] On packaging production lines for liquid foods such as milk, marking the packaging boxes with inkjet printing (such as production date and shelf life) is an essential step. Currently, most production lines use a single conveyor belt for transport, with manual feeding. This method has several significant drawbacks: First, the limited feeding stations on a single conveyor line restrict overall feeding efficiency, becoming a bottleneck for production efficiency. Second, inconsistent feeding rhythms result in uneven spacing of the boxes on the conveyor belt, sometimes tightly packed and sometimes too far apart. This unstable transport state severely affects the recognition and printing quality of subsequent inkjet printing stations, easily leading to problems such as missed printing, inaccurate coding positions, or overlapping characters, requiring frequent machine stops for adjustments and reducing production efficiency. Furthermore, existing conveyor guardrails are mostly fixed structures, unable to adapt to the transport needs of packaging boxes of different sizes. Changing product specifications requires machine stops for adjustments or even component replacement, which is time-consuming and labor-intensive. Utility Model Content
[0003] Therefore, in view of the above problems, this utility model proposes a conveying mechanism for milk carton inkjet printing that has high production efficiency, can be adapted to packaging boxes of different sizes, and has uniform spacing between packaging boxes.
[0004] This utility model is achieved through the following technical solution: A conveying mechanism for inkjet printing on milk cartons, comprising: First conveyor belt, second conveyor belt, and third conveyor belt; The first and second conveyor belts are used to hold milk cartons, and their ends converge at the beginning of the third conveyor belt. Wherein, the end of the first conveyor belt is located on one side of the beginning of the third conveyor belt, and the end of the second conveyor belt is located on the other side of the beginning of the third conveyor belt; Guardrails are provided on both sides of the first and second conveyor belts; The guardrail is configured to prevent milk cartons from detaching from the conveyor belt during transport and to guide the milk cartons toward the beginning of the third conveyor belt at the ends of the first and second conveyor belts.
[0005] As a further improvement of this utility model, the first conveyor belt and the second conveyor belt are arranged symmetrically with respect to the center line of the third conveyor belt.
[0006] As a further improvement of this utility model, the guardrail has guide sections formed at the ends of the first conveyor belt and the second conveyor belt, respectively; The two guide sections are inclined at opposite angles relative to the conveying direction of their respective conveyor belts, and the ends of the two guide sections converge or are adjacent to each other in the central area of the beginning of the third conveyor belt, thereby forming a converging guide channel.
[0007] As a further improvement of this utility model, baffles are provided on both sides of the first conveyor belt and the second conveyor belt, and a telescopic cylinder is provided on one side of the baffle. The telescopic cylinder is used to drive the baffle to move along the width direction of the first conveyor belt or the second conveyor belt. The telescopic cylinders on the first and second conveyor belts are configured to extend and retract alternately to drive the baffles to alternately intercept or release milk cartons, thereby realizing the batch collection and transportation of milk cartons.
[0008] As a further improvement of this utility model, a milk carton spacing adjustment mechanism is provided on the third conveyor belt; The milk carton spacing adjustment mechanism includes two rollers disposed opposite to each other on both sides of the third conveyor belt, and a rotary motor that drives the rollers to rotate. The linear velocity of the roller is configured to be less than the conveying speed of the third conveyor belt; When the milk cartons pass between the two rollers, they are held by the rollers and slowed down because the linear speed of the rollers is less than the conveying speed of the third conveyor belt. This causes the milk cartons to be redistributed on the third conveyor belt, ultimately creating a uniform spacing between the milk cartons after they have passed the rollers, which facilitates subsequent coding operations.
[0009] As a further improvement of this utility model, the distance between the two rollers can be adjusted.
[0010] As a further improvement of this utility model, motor mounting brackets are provided on both sides of the third conveyor belt; The motor mounting bracket is provided with a slide rail and a slider that can slide along it, and the rotating motor is fixedly mounted on the slider; The motor mounting bracket is also provided with a lead screw, which is connected to the slider via a threaded drive. A handwheel is provided at one end of the lead screw. By rotating the handwheel, the lead screw is driven to rotate, thereby driving the slider and the rotating motor mounted on it to move synchronously, so as to adjust the distance between the two rollers.
[0011] As a further improvement of this utility model, the spacing between the inner guardrail and the outer guardrail of the guardrails on both sides of the first conveyor belt and the second conveyor belt is adjustable.
[0012] As a further improvement of this utility model, the guardrail includes a guide rod and a mounting base for the guide rod to pass through; The mounting base is provided with a through hole for the guide rod to pass through, and one side of the through hole has an opening, so that the inner part of the guide rod is exposed outside the opening, for direct contact with and guidance of the milk carton.
[0013] As a further improvement of this utility model, mounting frames are provided on the frames on both sides of the conveyor belt, and uprights are rotatably connected to the mounting frames; The upper end of the upright has a horizontal opening, through which a transverse connecting rod passes, and the end of the transverse connecting rod is connected to the outside of the mounting base. The upper end of the upright is also provided with a locking screw. The locking screw is vertically inserted into the opening and abuts against the side wall of the transverse connecting rod. The locking screw and the upright are threaded together to lock the relative position of the transverse connecting rod and the upright.
[0014] The beneficial effects of this utility model are as follows: In this utility model, milk cartons are placed manually or mechanically on the first and second conveyor belts respectively. The milk cartons are conveyed forward under the action of the first or second conveyor belt. The guardrails on both sides can effectively prevent the milk cartons from shifting or detaching from the first or second conveyor belt during the conveying process. When the milk cartons are conveyed to the end of the first or second conveyor belt, they enter the third conveyor belt from both sides of the beginning of the third conveyor belt under the guidance of the guardrails. Then, the third conveyor belt conveys the milk cartons to the inkjet printing device at the end to complete the inkjet printing operation. By setting two parallel first and second conveyor belts, milk cartons can be loaded from both sides at the same time, improving the loading efficiency. The guardrails can prevent the milk cartons from detaching from the first or second conveyor belt and guide the conveying direction of the milk cartons, ensuring that the milk cartons accurately enter the third conveyor belt and avoiding blockage or jamming. The overall structure is simple and easy to operate, which can effectively improve the conveying efficiency and stability of milk cartons before inkjet printing, thus making it suitable for batch inkjet printing and conveying operations of milk cartons. Attached Figure Description
[0015] The preferred embodiments of this utility model will be described in detail below with reference to the accompanying drawings to help understand the purpose and advantages of this utility model, wherein: Figure 1 This is a schematic diagram of the structure of an embodiment of the present utility model; Figure 2 Corresponding to this utility model Figure 1 Enlarged view of a portion of point A in the middle; Figure 3 Corresponding to this utility model Figure 1 Enlarged view of section B in the middle.
[0016] Numbered in the diagram: 1. First conveyor belt; 2. Second conveyor belt; 3. Third conveyor belt; 4. Milk carton; 5. Guardrail; 5. Guide section; 501. Converging guide channel; 502. Guide rod; 503. Mounting base; 504. Baffle plate; 6. Telescopic cylinder; 7. Roller; 8. Rotary motor; 9. Motor mounting bracket; 10. Slide rail; 11. Slider; 12. Lead screw; 13. Mounting bracket; 14. Upright pole; 15. Horizontal connecting rod; 16. Locking screw; 17. Detailed Implementation
[0017] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments.
[0018] The directional terms such as up, down, left, right, front, back, front, back, top, and bottom mentioned or possibly used in this specification are defined relative to the construction shown in the accompanying drawings. The terms "inner" and "outer" refer to directions toward or away from the geometric center of a specific component, respectively. These are relative concepts and may therefore vary depending on their location and usage. Therefore, these or other directional terms should not be interpreted as restrictive.
[0019] refer to Figures 1 to 3 The present utility model embodiment discloses that: A milk carton coding conveying mechanism includes a first conveyor belt 1, a second conveyor belt 2, and a third conveyor belt 3. The first and second conveyor belts 1 and 2 are used to place milk cartons 4 manually or mechanically, and their ends converge at the beginning of the third conveyor belt 3. A coding device is installed at the end of the third conveyor belt 3 for coding the milk cartons 4. The end of the first conveyor belt 1 is located on one side of the beginning of the third conveyor belt 3, and the end of the second conveyor belt 2 is located on the other side of the beginning of the third conveyor belt 3. Guardrails 5 are provided on both sides of the first and second conveyor belts 1 and 2. The guardrails 5 are configured to prevent the milk cartons 4 from detaching from the conveyor belts during transport, and to guide the milk cartons 4 towards the beginning of the third conveyor belt 3 at the ends of the first and second conveyor belts 1 and 2, respectively. The milk cartons 4 are placed on the first and second conveyor belts 1 and 2 manually or mechanically. The milk carton 4 is conveyed forward by the conveyor belt 2. The guardrails 5 on both sides can effectively prevent the milk carton 4 from shifting or detaching from the first conveyor belt 1 or the second conveyor belt 2 during the conveying process. When the milk carton 4 is conveyed to the end of the first conveyor belt 1 or the second conveyor belt 2, it enters the third conveyor belt 3 from both sides of the beginning of the third conveyor belt 3 under the guidance of the guardrails 5. Then, the third conveyor belt 3 conveys the milk carton 4 to the inkjet printer at the end to complete the inkjet printing operation. By setting two parallel first conveyor belts 1 and second conveyor belts 2, milk carton 4 can be fed from both sides at the same time, which improves the feeding efficiency. The guardrails 5 can not only prevent the milk carton 4 from detaching from the first conveyor belt 1 or the second conveyor belt 2, but also guide the conveying direction of the milk carton 4 to ensure that the milk carton 4 accurately enters the third conveyor belt 3 and avoids blockage or jamming. The overall structure is simple and easy to operate, which can effectively improve the conveying efficiency and stability of the milk carton 4 before inkjet printing, and is therefore suitable for batch inkjet printing conveying of milk carton 4.
[0020] Based on this, the first conveyor belt 1 and the second conveyor belt 2 are arranged symmetrically with respect to the centerline of the third conveyor belt 3. The guardrail 5 has guide sections 501 formed at the ends of the first conveyor belt 1 and the second conveyor belt 2, respectively. The two guide sections 501 are inclined at opposite angles relative to the conveying direction of their respective conveyor belts, and their ends converge or are adjacent to each other in the central area of the beginning of the third conveyor belt 3, thus forming a converging guide channel 502. The guide sections 501 at the ends of the guardrail 5 are no longer parallel to the first conveyor belt 1 or the second conveyor belt 2. The conveyor belts are set at a certain angle to form a gradually narrowing "V"-shaped (inner) or funnel-shaped (outer) channel, with the end pointing towards the starting center area of the third conveyor belt 3. When the milk carton 4 is conveyed to the end along the first conveyor belt 1 and the second conveyor belt 2, it will move towards the center area of the beginning of the third conveyor belt 3 along the inclined direction of the guide section 501, and finally converge in the center area of the beginning of the third conveyor belt 3. This allows the materials from both sides to flow smoothly and orderly into the third conveyor belt 3, avoiding collisions, jamming or tipping of the milk carton 4 at the convergence point, and ensuring the continuity and stability of the conveying process.
[0021] While both conveyor belts (the first conveyor belt 1 and the second conveyor belt 2) are fed simultaneously, interference and impact may occur when materials arrive from both sides. Baffle plates 6 are installed on both sides of the first conveyor belt 1 and the second conveyor belt 2. A telescopic cylinder 7 is driven to one side of each baffle plate 6, and the telescopic cylinder 7 drives the baffle plate 6 to move along the width direction of the first conveyor belt 1 or the second conveyor belt 2. The telescopic cylinders 7 on the first conveyor belt 1 and the second conveyor belt 2 are configured to extend and retract alternately, so that the baffle plates 6 alternately intercept or release milk cartons 4, achieving batch collection and transportation of the milk cartons 4. In actual operation, when a milk carton 4 on one side of the conveyor belt (e.g., the first conveyor belt 1) is transported to the position of the baffle plate 6 on that side, that side... The telescopic cylinder 7 retracts, causing the baffle plate 6 to move to one side, allowing the milk cartons 4 to continue forward. Meanwhile, the telescopic cylinder 7 on the other side (second conveyor belt 2) remains extended, with the conveyor baffle plate 6 blocking the conveying of milk cartons 4 on that side. Subsequent milk cartons 4 are intercepted in batches in front of the baffle plate 6. After the milk cartons 4 on the first conveyor belt 1 have been released and conveyed to the third conveyor belt 3, the telescopic cylinder 7 corresponding to the second conveyor belt 2 retracts, causing its baffle plate 6 to move and release the milk cartons 4 on that side. This allows them to enter the third conveyor belt 3 in batches and in an orderly manner for subsequent inkjet printing operations, effectively avoiding the chaos and accumulation of milk cartons 4 during the merging process, preventing mutual interference and impact when materials arrive from both sides, and improving the efficiency of the entire conveying and inkjet printing process.
[0022] Furthermore, to ensure that the milk cartons 4 form a uniform spacing on the third conveyor belt 3 for subsequent coding operations, a milk carton 4 spacing adjustment mechanism is provided on the third conveyor belt 3. This mechanism includes two rollers 8 disposed opposite each other on both sides of the third conveyor belt 3, and a rotary motor 9 that drives the rollers 8 to rotate. The linear velocity of the rollers 8 is configured to be less than the conveying speed of the third conveyor belt 3. When the collected milk cartons 4 pass between the two rollers 8, they are clamped by the rollers 8 and decelerated because the linear velocity of the rollers 8 is less than the conveying speed of the third conveyor belt 3, thereby redistributing the subsequent milk cartons 4 on the third conveyor belt 3. Ultimately, this creates a uniform spacing between the milk cartons 4 after passing through the rollers 8, facilitating subsequent coding operations. Specifically, when the collected milk cartons 4 pass between two rollers 8, they are clamped by the rollers 8 and decelerated because the linear velocity of the rollers 8 is less than the conveying speed of the third conveyor belt 3. This causes the clamped milk cartons 4 to gradually move away from the previous milk carton 4 on the third conveyor belt 3 and redistribute after passing through the rollers 8, ultimately creating a uniform and stable spacing between the milk cartons 4. This uniform spacing ensures that the subsequent coding equipment can perform accurate and clear coding operations on each milk carton 4, avoiding the problem of missed coding caused by uneven spacing, and improving coding quality and production efficiency.
[0023] Meanwhile, to accommodate the spacing adjustment requirements of milk cartons 4 of different sizes, the spacing between the two rollers 8 is adjustable. Specifically, motor mounting brackets 10 are provided on both sides of the third conveyor belt 3. The motor mounting brackets 10 are equipped with slide rails 11 and sliders 12 that can slide along them. The rotating motor 9 is fixedly mounted on the sliders 12. A lead screw 13 is also provided on the motor mounting brackets 10, and the lead screw 13 is connected to the slider 12 via a threaded transmission. A handwheel is provided at one end of the lead screw 13. Rotating the handwheel drives the lead screw 13 to rotate, thereby causing the slider 12 and the rotating motor 9 mounted thereon to move synchronously, thus adjusting the spacing between the two rollers 8. In actual operation, the operator only needs to rotate the handwheel to move the slider 12 along the slide rail 11 via the lead screw 13, thereby causing the rotating motor 9 and the rollers 8 to move synchronously, thus adjusting the spacing between the rollers 8. This adjustment method is simple and convenient, requiring no other tools, and the lead screw 13 transmission adjustment accuracy is high, meeting the spacing adjustment requirements of milk cartons 4 of different sizes.
[0024] Accordingly, in order to accommodate the spacing adjustment requirements of milk cartons 4 of different sizes, the spacing between the inner guardrail 5 and the outer guardrail 5 on both sides of the first conveyor belt 1 and the second conveyor belt 2 can be adjusted.
[0025] Specifically, the guardrail 5 includes a guide rod 503 and a mounting base 504 through which the guide rod 503 passes. The mounting base 504 has a through hole through which the guide rod 503 passes, and one side of the through hole has an opening, so that the inner part of the guide rod 503 is exposed outside the opening, for directly abutting against and guiding the milk carton 4. The through hole on the mounting base 504 is designed to be open on one side, so that after the cylindrical guide rod 503 is installed, its inner guide surface is completely exposed outside the channel, ensuring that in any adjustment position, the packaging box only contacts the smooth guide rod 503, avoiding interference with the mounting base 504, and ensuring the reliability and smoothness of the guidance.
[0026] Mounting brackets 14 are provided on both sides of the first conveyor belt 1 and the second conveyor belt 2. Upright poles 15 are rotatably connected to the mounting brackets 14. A horizontal opening is provided at the upper end of the upright pole 15, through which a transverse connecting rod 16 passes. The end of the transverse connecting rod 16 is connected to the outer side of the mounting base 504. A locking screw 17 is also provided at the upper end of the upright pole 15. The locking screw 17 vertically passes through the opening and abuts against the side wall of the transverse connecting rod 16. The locking screw 17 is connected to the upright pole 1... 5. The relative positions of the transverse connecting rod 16 and the upright rod 15 are locked by threaded connection. In actual operation, when it is necessary to adjust the spacing of the guardrail 5, simply loosen the locking screw 17, rotate the upright rod 15 to the required angle, then move the transverse connecting rod 16 to the appropriate position, and finally tighten the locking screw 17 to fix the guardrail 5 in the required position. This adjustment method is both convenient and stable, and can ensure that the guardrail 5 maintains a stable spacing and position during the conveying process, thereby providing a reliable guiding effect for the conveying of the milk carton 4.
[0027] It is worth mentioning that the specific transmission structure of the above-mentioned inkjet printer and conveyor belt is a conventional technical means that can be directly purchased from the market. It has not been improved in this embodiment, so it is not shown in the figure, and its specific structure will not be described in detail here.
[0028] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this utility model, and not to limit it. Although this utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent substitutions for some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this utility model.
Claims
1. A conveying mechanism for inkjet printing on milk cartons, characterized in that, include: First conveyor belt (1), second conveyor belt (2) and third conveyor belt (3); The first conveyor belt (1) and the second conveyor belt (2) are used to place milk cartons (4), and their ends converge at the beginning of the third conveyor belt (3); Wherein, the end of the first conveyor belt (1) is located on one side of the beginning of the third conveyor belt (3), and the end of the second conveyor belt (2) is located on the other side of the beginning of the third conveyor belt (3); Guardrails (5) are provided on both sides of the first conveyor belt (1) and the second conveyor belt (2); The guardrail (5) is configured to prevent the milk carton (4) from detaching from the conveyor belt during transport and to guide the milk carton (4) toward the beginning of the third conveyor belt (3) at the ends of the first conveyor belt (1) and the second conveyor belt (2).
2. The conveying mechanism for inkjet printing on milk cartons according to claim 1, characterized in that: The first conveyor belt (1) and the second conveyor belt (2) are arranged symmetrically with respect to the center line of the third conveyor belt (3).
3. A conveying mechanism for inkjet printing on milk cartons according to claim 1 or 2, characterized in that: The guardrail (5) has guide sections (501) formed at the ends of the first conveyor belt (1) and the second conveyor belt (2); The two guide sections (501) are arranged at opposite angles relative to the conveying direction of their respective conveyor belts, and the ends of the two guide sections (501) converge or are adjacent to each other in the central area of the beginning of the third conveyor belt (3), thereby forming a converging guide channel (502).
4. The conveying mechanism for inkjet printing on milk cartons according to claim 1, characterized in that: The first conveyor belt (1) and the second conveyor belt (2) are provided with baffles (6) on both sides. A telescopic cylinder (7) is provided on one side of the baffle (6). The telescopic cylinder (7) is used to drive the baffle (6) to move along the width direction of the first conveyor belt (1) or the second conveyor belt (2). The telescopic cylinders (7) on the first conveyor belt (1) and the second conveyor belt (2) are configured to extend and retract in turn to drive the baffle plate (6) to alternately intercept or release the milk carton (4), thereby realizing the batch collection and transportation of the milk carton (4).
5. A conveying mechanism for inkjet printing on milk cartons according to claim 1 or 4, characterized in that: The third conveyor belt (3) is provided with a milk box (4) spacing adjustment mechanism; The milk carton (4) spacing adjustment mechanism includes two rollers (8) arranged opposite to each other on both sides of the third conveyor belt (3), and a rotary motor (9) that drives the rollers (8) to rotate. The linear velocity of the roller (8) is configured to be less than the conveying speed of the third conveyor belt (3); When the milk cartons (4) pass between the two rollers (8), they are held by the rollers (8) and slowed down because the linear speed of the rollers (8) is less than the conveying speed of the third conveyor belt (3). This causes the subsequent milk cartons (4) to be redistributed on the third conveyor belt (3), and finally a uniform spacing is formed between the milk cartons (4) after passing through the rollers (8), so as to facilitate the subsequent coding operation.
6. The conveying mechanism for inkjet printing on milk cartons according to claim 5, characterized in that: The spacing between the two rollers (8) can be adjusted.
7. A conveying mechanism for inkjet printing on milk cartons according to claim 6, characterized in that, Motor mounting brackets (10) are provided on both sides of the third conveyor belt (3); The motor mounting bracket (10) is provided with a slide rail (11) and a slider (12) that can slide along it, and the rotating motor (9) is fixedly mounted on the slider (12); The motor mounting bracket (10) is also provided with a lead screw (13), and the lead screw (13) is connected to the slider (12) by a threaded transmission. One end of the lead screw (13) is equipped with a handwheel. By rotating the handwheel, the lead screw (13) is driven to rotate, thereby driving the slider (12) and the rotating motor (9) mounted on it to move synchronously, so as to adjust the distance between the two rollers (8).
8. The conveying mechanism for inkjet printing on milk cartons according to claim 1, characterized in that: The guardrails (5) on both sides of the first conveyor belt (1) and the second conveyor belt (2) are adjustable in terms of the spacing between the inner guardrail (5) and the outer guardrail (5).
9. A conveying mechanism for inkjet printing on milk cartons according to claim 8, characterized in that: The guardrail (5) includes a guide rod (503) and a mounting base (504) through which the guide rod (503) passes; The mounting base (504) is provided with a through hole for the guide rod (503) to pass through. One side of the through hole has an opening, so that the inner part of the guide rod (503) is exposed outside the opening, for direct contact with and guidance of the milk carton (4).
10. A conveying mechanism for inkjet printing on milk cartons according to claim 9, characterized in that: Mounting frames (14) are provided on both sides of the first conveyor belt (1) and the second conveyor belt (2), and uprights (15) are rotatably connected to the mounting frames (14); The upper end of the upright (15) is provided with a horizontal opening, and a transverse connecting rod (16) is inserted through the opening. The end of the transverse connecting rod (16) is connected to the outside of the mounting base (504). The upper end of the upright (15) is also provided with a locking screw (17). The locking screw (17) is vertically inserted into the opening and abuts against the side wall of the transverse connecting rod (16). The locking screw (17) and the upright (15) are threaded together to lock the relative position of the transverse connecting rod (16) and the upright (15).