Wafer processing machine with positioning structure

Abstract

The invention relates to the field of semiconductor processing, and discloses a wafer processing machine with a positioning structure, which comprises a case, two groups of storage boxes are arranged in the case and are symmetrically distributed on the left side and the right side of an inner cavity of the case; and the upper side and the lower side of the inner wall of the storage box are fixedly connected with multiple sets of second supports and first supports which are the same in number correspondingly, first rotating shafts and first conveying rollers are rotationally installed in the first supports, and second rotating shafts and second conveying rollers are rotationally installed in the second supports. According to the device, the multiple sets of feeding strips are arranged and surround the outer side of the belt, when the first rotating shaft drives the first conveying roller to rotate through the belt, the feeding strips can clamp the wafer body located on the upper surface of the first conveying belt and drive the wafer body upwards through circulating motion, and therefore the continuous feeding function of the wafer body is achieved; and the step of replacing the cloth in the storage box is omitted, so that the working efficiency of the device is remarkably improved.

Description

Technical Field

[0001] This application relates to the field of semiconductor processing technology, and in particular to a wafer processing machine with a positioning structure. Background Technology

[0002] In the wet wafer processing, a wafer transfer mechanism is often required. Its function is to transport the wafers to various processing units for processing. The wafers to be processed are placed in wafer cassettes, which typically contain multiple layers of stacked wafers for pre-feeding before processing and post-processing storage. Inside the wet wafer processing machine, a robotic arm, aided by a suction cup at its end, picks up the top layer of wafers from the wafer cassette and carries them to the processing position. After processing, they are placed in another storage cassette, integrating wafer picking, processing, and unloading into a single process. In terms of wafer processing capabilities, existing technologies lack effective positioning and transportation methods within wafer cassettes. Due to the fragility of wafers, traditional rigid limiting structures have a certain probability of damaging the wafer periphery. Current technologies use internal slots to store and place wafers, but this method not only limits the efficiency of wafer loading and unloading (the robotic arm needs to be controlled to pick up the wafer at different positions), but also requires repeated replacement of storage cassettes for replenishment and unloading, which greatly reduces the working efficiency of the wafer processing machine. Therefore, it is urgent to solve this problem and redesign a wafer processing machine with a positioning structure. Summary of the Invention

[0003] This application proposes a wafer processing machine with a positioning structure, which has the advantage of high working efficiency, thereby solving the problem of low working efficiency in the prior art.

[0004] To achieve the above objectives, this application adopts the following technical solution: a wafer processing machine with a positioning structure, comprising a chassis, wherein the interior of the chassis is respectively equipped with... The processing area is located at the rear of the chassis. A robotic arm is located in front of the processing area, and a suction cup is fixedly installed at the end of the robotic arm; The storage box is configured in two sets and symmetrically distributed on the left and right sides of the inner cavity of the chassis. Multiple sets of the same number of brackets 2 and bracket 1 are fixedly connected to the upper and lower sides of the inner wall of the storage box. A rotating shaft 1 and a transport roller 1 are rotatably installed inside the bracket 1. A rotating shaft 2 and a transport roller 2 are rotatably installed inside the bracket 2. A belt is driven to the outer surface of the transport roller 1 and the transport roller 2. Multiple sets of equidistant feeding strips are fixedly connected to the outer surface of the belt. The wafer body is placed on the top of the feeding strip. A motor is installed on the side of the bracket 1 located at the rear. The motor is driven to the rotating shaft 1. This redesigned device achieves highly efficient wafer transfer. To achieve this, four sets of supports (one and two) are installed inside the storage box. Support one contains a rotating shaft and a transport roller, while support two contains a rotating shaft and a transport roller. A belt running vertically connects transport rollers one and two. Multiple sets of feeding strips fixed to the outside of the belt move up and down with the belt, enabling the wafer to move up and down within the storage box. The feeding strips are multiple sets and wrap around the outside of the belt. When the rotating shaft drives the transport roller to rotate via the belt, the feeding strips can clamp and lift the wafer located on the upper surface of the conveyor belt through cyclical motion, thus achieving continuous wafer replenishment. This eliminates the need to change the material in the storage box, significantly improving the device's efficiency.

[0005] Then, this device utilizes feeding strips evenly distributed on the outer surface of the conveyor belt. The feeding strips are integrally molded by injection molding and consist of support plates and limiting strips. The inner steps formed by the support plates support the wafer body. At the same time, the inner arc of the limiting strips positions and protects the outer surface of the wafer body. The rounded chamfer at the top of the limiting strips guides the wafer body to its top. The step design at the bottom of the support plates can also clamp the wafer body located on the upper surface of the conveyor belt and move it upward to the inner cavity of the storage box. The above process is reversible. The wafer body can be fed into the storage box on the left and unloaded into the storage box on the right, which not only has high working efficiency but also better stability.

[0006] Finally, the four sets of support 1, rotating shaft 1, conveyor roller 1, support 2, rotating shaft 2, conveyor roller 2, and belts in this device are powered by motors. To achieve power synchronization of the four sets of rotating shaft 1 and conveyor roller 1, this device sets drive shaft 1, drive shaft 2, and universal joints between two adjacent sets of rotating shaft 1. Drive shaft 1 and drive shaft 2 are slidably connected by splines, allowing them to slide against each other and ensuring power connection. By setting drive shaft 1 and drive shaft 2 in two sets of universal joints, the motor drives the first set of rotating shaft 1 to rotate, and can drive the other three sets of rotating shaft 1 to rotate synchronously through the universal joints, drive shaft 1, and drive shaft 2. The power synchronization is smooth and highly reliable.

[0007] Preferably, the machine casing has material inlets on both the left and right sides. Conveyor belt 1 and conveyor belt 2 are respectively installed inside the two sets of material inlets, located directly below the storage box. The two sets of conveyor belt 1 have the same transport direction, while the two sets of belts and feeding strips have opposite transport directions.

[0008] Preferably, the first transport roller is fixedly sleeved on the outer surface of the first rotating shaft, and both ends of the first rotating shaft are fixedly connected to universal joints. One set of universal joints is fixedly connected to the first drive shaft, and another set of universal joints is fixedly connected to the second drive shaft. The first drive shaft and the second drive shaft are slidably connected by splines.

[0009] Preferably, the feeding strip is made of rubber block and is adapted to abut against the outer surface of the wafer body.

[0010] Preferably, the feeding bar includes a support plate fixedly connected to the outside of the belt, a limiting strip fixedly connected to the top of the support plate, the inner side of the limiting strip being fixedly connected to the outer side of the belt, and a slot being provided between the support plate and the limiting strip.

[0011] Preferably, the limiting strip has an arc on the side near the wafer body that is adapted to the wafer body, and the top of the limiting strip has an arc chamfer.

[0012] Preferably, a protective shell is fixedly connected to the top of the storage box, and the protective shell covers the outside of the second support, the second rotating shaft, the second conveying roller and the second limiting ring. An outer cylinder is fixedly connected to the outer surface of the storage box, and a support column is fixedly connected to the top of the inner side of the machine box. The outer cylinder is adapted to be inserted into the top of the support column.

[0013] Preferably, the second transport roller is fixedly sleeved on the outer surface of the second rotating shaft, the first bracket and the second bracket are longitudinally opposite each other, the two sides of the outer surface of the first transport roller are fixedly connected to the first limiting ring, the two sides of the outer surface of the second transport roller are fixedly connected to the second limiting ring, and the belt is limited between the two sets of first limiting rings and the two sets of second limiting rings.

[0014] The beneficial effects of this invention are as follows: 1. This device has been redesigned to achieve efficient wafer transfer. To achieve this, the device has four sets of support brackets (one and two) inside the storage box. Support bracket one contains a rotating shaft and a transport roller, while support bracket two contains a rotating shaft and a transport roller. A belt running vertically connects the transport rollers. Multiple sets of feeding strips fixed to the outside of the belt move up and down with the belt, enabling the wafer to move up and down within the storage box. The feeding strips are multiple sets and wrap around the outside of the belt. When the rotating shaft drives the transport roller to rotate via the belt, the feeding strips can clamp and lift the wafer located on the upper surface of the conveyor belt through cyclical motion, thereby achieving continuous wafer replenishment. This eliminates the need to change the material in the storage box, significantly improving the device's efficiency.

[0015] 2. Then, this device utilizes feeding strips evenly distributed on the outer surface of the conveyor belt. The feeding strips are integrally molded by injection molding and consist of support plates and limiting strips. The inner steps formed by the support plates support the wafer body. At the same time, the inner arc of the limiting strips positions and protects the outer surface of the wafer body. The rounded chamfer at the top of the limiting strips guides the wafer body to its top. The step design at the bottom of the support plates can also clamp the wafer body located on the upper surface of the conveyor belt and move it upward to the inner cavity of the storage box. The above process is reversible. The wafer body can be fed into the storage box on the left and unloaded into the storage box on the right, which not only has high working efficiency but also better stability.

[0016] 3. Finally, the four sets of support 1, rotating shaft 1, conveyor roller 1, support 2, rotating shaft 2, conveyor roller 2, and belts in this device are powered by motors. To achieve power synchronization of the four sets of rotating shaft 1 and conveyor roller 1, this device sets drive shaft 1, drive shaft 2, and universal joints between adjacent sets of rotating shaft 1. Drive shaft 1 and drive shaft 2 are slidably connected by splines, allowing them to slide against each other and ensuring power connection. By setting drive shaft 1 and drive shaft 2 in two sets of universal joints, the motor drives the first set of rotating shaft 1 to rotate, and can drive the other three sets of rotating shaft 1 to rotate synchronously through the universal joints, drive shaft 1, and drive shaft 2. The power synchronization is smooth and highly reliable. Attached Figure Description

[0017] The accompanying drawings, which form part of this specification, illustrate embodiments disclosed in this application and, together with the specification, serve to explain the principles of this application in a clear and understandable manner.

[0018] This disclosure will become clearer with reference to the accompanying drawings and the following detailed description, wherein: Figure 1 This is a schematic diagram of the structure of the wafer body, rotating shaft 1, transport roller 1, limiting ring 1, transmission shaft 1, limiting ring 2, belt and feeding bar of the present invention; Figure 2 This is a front view diagram of the overall structure of the present invention; Figure 3 This is a top view of the internal structure of the chassis of the present invention; Figure 4 This is a front sectional view of the storage box of the present invention; Figure 5 For the present invention Figure 4 Enlarged schematic diagram of the structure at point A; Figure 6 For the present invention Figure 4 Enlarged schematic diagram of the structure at point B; Figure 7 This is a schematic diagram of the internal structure of the storage box of the present invention; Figure 8This is a top sectional view of the storage box of the present invention; Figure 9 This is a schematic diagram showing the separation of the bracket 1, rotating shaft 1, transport roller 1, limiting ring 1, transmission shaft 1, transmission shaft 2 and motor of the present invention; Figure 10 This is a schematic diagram of the feeding bar structure of the present invention.

[0019] The components include: 1. Chassis; 2. Processing area; 3. Robotic arm; 4. Suction cup; 5. Conveyor belt one; 6. Conveyor belt two; 7. Support column; 8. Storage box; 9. Outer cylinder; 10. Protective shell; 11. Wafer body; 12. Support one; 13. Rotating shaft one; 14. Transport roller one; 15. Limiting ring one; 16. Drive shaft one; 17. Drive shaft two; 18. Motor; 19. Support two; 20. Rotating shaft two; 21. Transport roller two; 22. Limiting ring two; 23. Belt; 24. Feeding bar; 241. Support plate; 242. Limiting bar; 243. Empty slot; 25. Universal joint. Detailed Implementation

[0020] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0021] Please see Figures 1-10 This embodiment discloses a wafer processing machine with a positioning structure, including a chassis 1, and the interior of the chassis 1 is respectively equipped with... Processing area 2 is located on the rear side inside chassis 1; Robotic arm 3 is located in front of processing area 2, and a suction cup 4 is fixedly installed at the end of robotic arm 3; The storage box 8 is configured in two sets and symmetrically distributed on the left and right sides of the inner cavity of the chassis 1. Multiple sets of the same number of brackets 19 and brackets 12 are fixedly connected to the upper and lower sides of the inner wall of the storage box 8, respectively. The brackets 12 are rotatably mounted with a rotating shaft 13 and a transport roller 14. The brackets 29 are rotatably mounted with a rotating shaft 20 and a transport roller 21. The outer surfaces of the transport rollers 14 and 21 are connected to a belt 23. Multiple sets of equidistant feeding strips 24 are fixedly connected to the outer surface of the belt 23. The wafer body 11 is placed on the top of the feeding strips 24. A motor 18 is installed on the side of the rear bracket 12 and is connected to the rotating shaft 13. This device has been redesigned to achieve efficient transfer of the wafer body 11. To achieve this, four sets of supports 12 and 19 are installed inside the storage box 8. The support 12 houses the rotating shaft 13 and the transport roller 14, while the support 19 houses the rotating shaft 20 and the transport roller 21. A belt 23 is connected between the transport roller 14 and the transport roller 21, and multiple sets of feeding strips 24 fixedly connected to the outside of the belt 23 move up and down with the belt 23 to achieve the up and down movement of the wafer body 11 within the storage box 8. The feeding strips 24 are multiple sets and surround the outside of the belt 23. When the rotating shaft 13 drives the transport roller 14 to rotate through the belt 23, the feeding strips 24 can clamp and move the wafer body 11 located on the upper surface of the conveyor belt 5 through cyclical movement, thereby achieving continuous feeding of the wafer body 11. This eliminates the need to change the material in the storage box 8 and significantly improves the working efficiency of the device.

[0022] Then, the device utilizes feeding strips 24 evenly distributed on the outer surface of the belt 23. The feeding strips 24 are integrally formed by injection molding and consist of a support plate 241 and a limiting strip 242. The inner step formed by the support plate 241 supports the wafer body 11. At the same time, the arc on the inner side of the limiting strip 242 positions and protects the outer surface of the wafer body 11. The rounded chamfer at the top of the limiting strip 242 guides the wafer body 11 to be placed on top. The step design at the bottom of the support plate 241 can also clamp the wafer body 11 located on the upper surface of the conveyor belt 5 and move it upward to the inner cavity of the storage box 8. The above process is reversible. The wafer body 11 can be fed in the storage box 8 on the left and unloaded in the storage box 8 on the right. This not only has high working efficiency but also better stability.

[0023] Finally, the four sets of supports 12, shafts 13, conveyor rollers 14, supports 19, shafts 20, conveyor rollers 21, and belts 23 in this device are powered by motor 18. To achieve power synchronization of the four sets of shafts 13 and conveyor rollers 14, this device sets drive shafts 16, 17, and universal joints 25 between adjacent sets of shafts 13. Drive shafts 16 and 17 are slidably connected by splines, allowing them to slide against each other and ensuring power connection. By setting drive shafts 16 and 17 in the two sets of universal joints 25, the motor 18 drives the first set of shafts 13 to rotate, and the other three sets of shafts 13 can be driven to rotate synchronously through universal joints 25, drive shafts 16 and 17. The power synchronization is smooth and highly reliable.

[0024] In this embodiment, material inlets are provided on both the left and right sides of the chassis 1. Conveyor belt 5 and conveyor belt 6 located directly below the storage box 8 are installed inside the two sets of material inlets respectively. The transport directions of the two sets of conveyor belts 5 are the same, while the transport directions of the two sets of belts 23 and feeding strips 24 are opposite. This device is equipped with two sets of storage boxes 8, and below the left and right sets of storage boxes 8 are a first conveyor belt 5 for feeding and a second conveyor belt 6 for discharging. The wafer body 11 to be processed can be transported by the first conveyor belt 5 to the bottom of the left storage box 8, and then moved upward through the storage box 8. After processing, it is driven by the robotic arm 3 and the suction cup 4 and placed in the right storage box 8, and then moved downward to the second conveyor belt 6 to complete the discharge. This process keeps the first set of wafer bodies 11 located at the top of the left storage box 8 in a fixed position, reducing the adjustment time of the robotic arm 3 and the suction cup 4, which helps to improve the working efficiency of the device.

[0025] In this embodiment, the transport roller 14 is fixedly sleeved on the outer surface of the rotating shaft 13. Both ends of the rotating shaft 13 are fixedly connected to universal joints 25. One set of universal joints 25 is fixedly connected to the drive shaft 16, and another set of universal joints 25 is fixedly connected to the drive shaft 27. The drive shaft 16 and the drive shaft 27 are slidably connected by splines. like Figure 4 As shown, the rotating shaft 13 can drive the conveyor roller 14 and belt 23 to rotate under the drive of the motor 18, thereby driving the feeding strip 24 to move up and down in a circular motion. The two adjacent sets of rotating shafts 13 are vertically distributed. If they are not coaxial, they can be driven by the transmission shaft 16, the transmission shaft 27 and the universal joint 25.

[0026] In this embodiment, the feeding bar 24 is made of rubber block and is adapted to abut against the outer surface of the wafer body 11. The flexible material of the feed bar 24 can provide all-round protection for the wafer body 11, and can also adapt through deformation when flipping.

[0027] In this embodiment, the feeding bar 24 includes a support plate 241 fixedly connected to the outside of the belt 23. A limiting strip 242 is fixedly connected to the top of the support plate 241. The inner side of the limiting strip 242 is fixedly connected to the outer side of the belt 23. A slot 243 is provided between the support plate 241 and the limiting strip 242. like Figure 10 As shown, the bottom step design of the support plate 241, together with the limiting strip 242, can provide support for the wafer body 11 while protecting and positioning it. The slot 243 provides deformation space for the support plate 241 and the limiting strip 242 when flipped to the outside of the belt 23.

[0028] In this embodiment, the limiting strip 242 has an arc that matches the wafer body 11 on the side near the wafer body 11, and the top of the limiting strip 242 has an arc chamfer. like Figure 10 As shown, the rounded chamfer at the top of the limiting strip 242 provides a guiding function when the wafer body 11 is placed on it.

[0029] In this embodiment, a protective shell 10 is fixedly connected to the top of the storage box 8. The protective shell 10 covers the outside of the support 19, the rotating shaft 20, the conveying roller 21 and the limiting ring 22. An outer cylinder 9 is fixedly connected to the outer surface of the storage box 8. A support column 7 is fixedly connected to the top of the inner side of the machine box 1. The outer cylinder 9 is adapted to be inserted into the top of the support column 7. like Figure 2 As shown, the protective shell 10 is used to protect the belt 23 and the feeding bar 24 located at the top. The storage box 8 is adapted to the top of the support column 7 through the outer cylinder 9 and can be disassembled at any time for maintenance and repair.

[0030] In this embodiment, the second transport roller 21 is fixedly sleeved on the outer surface of the second rotating shaft 20. The first bracket 12 and the second bracket 19 are longitudinally opposite each other. Limiting rings 15 are fixedly connected to both sides of the outer surface of the first transport roller 14. Limiting rings 22 are fixedly connected to both sides of the outer surface of the second transport roller 21. The belt 23 is limited between the two sets of limiting rings 15 and the two sets of limiting rings 22. like Figure 4 , Figure 5 and Figure 6 As shown, the second limiting ring 22 and the first limiting ring 15 are used to limit the movement of the belt 23 on the outer surfaces of the first conveyor roller 14 and the second conveyor roller 21, so as to prevent it from deviating during the movement.

[0031] Working principle: When this device is working, such as Figure 2 and Figure 4 As shown, firstly, the wafer body 11 is transported from left to right along the upper surface of the conveyor belt 5 to directly below the storage box 8 on the left side, and then the motor 18 is started, as... Figure 4As shown, the wafer body 11 moves between the bottom belts 23 on the left and right sides via the conveyor belt 5. The motor 18 is started, and the first set of rotating shafts 13 connected to the motor 18 is driven. Then, through multiple sets of universal joints 25, all the rotating shafts 13 are driven. Finally, the transport rollers 14 and belts 23 are driven to rotate upward, causing the inner loading bar 24 to move upward and the outer loading bar 24 to move upward. When the loading bar 24 is driven to the bottom by the belt 23, the wafer body 11 located on the upper surface of the conveyor belt 5 is clamped by the support plate 241 and driven upward. The wafer body 11 is positioned by the arc surface of the inner side of the limiting bar 242. The four sets of loading bars 24 provide all-round positioning protection for the wafer body 11. Then, the next set of wafer bodies 11 moves to the bottom loading bar 24 for clamping and loading. This cycle repeats until multiple sets of wafer bodies 11 move upwards at equal intervals to the top of the storage box 8. During processing, the robotic arm 3 moves the suction cup 4 to the top of the storage box 8 on the left side, and uses the suction cup 4 to pick up the topmost wafer body 11, moving it to the processing area 2. After processing, the robotic arm 3 and the suction cup 4 move it to the top of the storage box 8 on the left side. Figure 4 As shown, the motor 18 on the right side reverses, driving the inner feed bar 24 to move downwards and the outer feed bar 24 to move upwards, placing the processed wafer body 11 inside the storage box 8 on the left side. Finally, the feed bar 24 drives it to the top of the second conveyor belt 6, where it is transported and unloaded by the second conveyor belt 6.

[0032] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A wafer processing machine with a positioning structure, comprising a chassis (1), characterized in that, The chassis (1) is equipped with the following components respectively: The processing area (2) is located on the rear side inside the chassis (1); A robotic arm (3) is located in front of the processing area (2), and a suction cup (4) is fixedly installed at the end of the robotic arm (3). The storage box (8) is configured in two sets and symmetrically distributed on the left and right sides of the inner cavity of the machine box (1). The upper and lower sides of the inner wall of the storage box (8) are respectively fixedly connected to a number of the same number of brackets two (19) and bracket one (12). The bracket one (12) is rotatably installed with a rotating shaft one (13) and a transport roller one (14). The bracket two (19) is rotatably installed with a rotating shaft two (20) and a transport roller two (21). The outer surfaces of the transport roller one (14) and the transport roller two (21) are connected to a belt (23). The outer surface of the belt (23) is fixedly connected to a number of equidistant feeding strips (24). The top of the feeding strip (24) is placed on the wafer body (11). A motor (18) is installed on the side of the bracket one (12) located at the rear. The motor (18) is connected to the rotating shaft one (13).

2. A wafer processing machine with a positioning structure according to claim 1, characterized in that, The machine box (1) has material inlets on both the left and right sides. The two sets of material inlets are respectively equipped with conveyor belt one (5) and conveyor belt two (6) located directly below the storage box (8). The two sets of conveyor belt one (5) have the same transport direction, while the two sets of belts (23) and feeding strips (24) have opposite transport directions.

3. A wafer processing machine with a positioning structure according to claim 2, characterized in that, The first transport roller (14) is fixedly sleeved on the outer surface of the first rotating shaft (13). Both ends of the first rotating shaft (13) are fixedly connected to universal joints (25). One set of universal joints (25) is fixedly connected to the first drive shaft (16), and another set of universal joints (25) is fixedly connected to the second drive shaft (17). The first drive shaft (16) and the second drive shaft (17) are slidably connected by splines.

4. A wafer processing machine with a positioning structure according to claim 3, characterized in that, The feeding bar (24) is made of rubber block and is adapted to abut against the outer surface of the wafer body (11).

5. A wafer processing machine with a positioning structure according to claim 4, characterized in that, The feeding bar (24) includes a support plate (241) fixedly connected to the outside of the belt (23). A limiting strip (242) is fixedly connected to the top of the support plate (241). The inner side of the limiting strip (242) is fixedly connected to the outer side of the belt (23). A slot (243) is provided between the support plate (241) and the limiting strip (242).

6. A wafer processing machine with a positioning structure according to claim 5, characterized in that, The limiting strip (242) has an arc that matches the wafer body (11) on the side near the wafer body (11), and the top of the limiting strip (242) has a rounded chamfer.

7. A wafer processing machine with a positioning structure according to claim 6, characterized in that, The top of the storage box (8) is fixedly connected to a protective shell (10), which covers the outside of the support (19), the rotating shaft (20), the transport roller (21) and the limiting ring (22). The outer surface of the storage box (8) is fixedly connected to an outer cylinder (9), and the top of the inner side of the machine box (1) is fixedly connected to a support column (7). The outer cylinder (9) is adapted to be inserted into the top of the support column (7).

8. A wafer processing machine with a positioning structure according to claim 7, characterized in that, The second transport roller (21) is fixedly sleeved on the outer surface of the second rotating shaft (20). The first bracket (12) and the second bracket (19) are longitudinally opposite each other. The first and second sides of the outer surface of the first transport roller (14) are fixedly connected to the first limiting ring (15). The second and second sides of the outer surface of the second transport roller (21) are fixedly connected to the second limiting ring (22). The belt (23) is limited between the two sets of first limiting rings (15) and the two sets of second limiting rings (22).

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