Injection molding waste powder recycling device

Abstract

The application relates to a waste crushing and recycling device for injection molding processing and belongs to the technical field of injection molding processing, which comprises a main crushing frame, a receiving frame fixedly connected to the top of the main crushing frame, a conveying frame fixedly connected to the bottom of the main crushing frame, a secondary crushing frame fixedly connected to the bottom of the conveying frame, a crushing roller rotatably connected to the inner wall of the main crushing frame, a rotary joint rotatably connected to the end of the crushing roller and extending to the outside of the main crushing frame, and a control box fixedly connected to the outer wall of the main crushing frame. The knocking rod and the air holes can be used for distributing the waste on the upper and lower sides of the crushing roller through the knocking rod when the injection molding waste is treated by the crushing and recycling device, so that the waste of different sizes is pre-broken and re-broken before and after crushing. Meanwhile, the mechanical energy for driving the flapping plate is converted into wind energy for conveying under the arrangement of the air holes, the waste is prevented from being adsorbed on the surface of the crushing roller, and the waste is synchronously cooled.

Description

Technical Field

[0001] This invention relates to the field of injection molding technology, and more specifically, to a waste material crushing and recycling device for injection molding. Background Technology

[0002] Injection molding is a method of shaping industrial products. Products are usually made using rubber injection molding and plastic injection molding. Injection molding can also be divided into injection molding compression molding and die casting. An injection molding machine is the main molding equipment that uses plastic molds to make plastic products of various shapes from thermoplastic or thermosetting materials. After injection molding, excess waste is usually generated. This waste can be crushed into granules for reuse, reducing waste.

[0003] In the prior art, a waste crushing and recycling device for injection molding, with publication number CN113459342B, includes: a sealed crushing chamber with a bottom discharge port at the bottom and a central fixed shaft symmetrically arranged parallel to each other in the middle of the sealed crushing chamber, and a communicating opening on the front of the sealed crushing chamber; and rotating crushing rollers symmetrically arranged inside the sealed crushing chamber. This invention crushes injection molding waste through the symmetrically arranged rotating crushing rollers in the sealed crushing chamber. Multiple crushing blades are installed on the rotating crushing rollers, and each rotating crushing roller has a corresponding blade rotating frame on its front. The blade rotating frame can store multiple crushing blades of different sizes at the same time. The crushing blades in the horizontal fitting groove are pulled out and detached by a vertical push plate, and then the stored crushing blades are pushed into the horizontal fitting groove for installation. This allows for quick replacement and installation of crushing blades, making the process more convenient and efficient.

[0004] In the prior art, a waste crushing and recycling device for injection molding, with publication number CN118493699B, belongs to the field of injection molding technology. It includes a drive assembly, a movable feeding assembly, a first crushing assembly, a second crushing assembly, and a leveling assembly. The drive assembly is located close to the movable feeding assembly, the first crushing assembly is located at the front end of the movable feeding assembly, the second crushing assembly is located close to the rear end of the movable feeding assembly, and the leveling assembly is located between the drive assembly and the movable feeding assembly. The movable feeding assembly includes a first base, a movable groove, a movable block, a chute, a slider, a feeding port, a fixed baffle, a first support plate, and a limiting plate. The movable groove is located on the first base, the movable block is located in the movable groove, the drive assembly is connected to one end of the movable block, the chute is located on the movable block, one end of the slider is located in the chute, the feeding port is located at the other end of the slider, the fixed baffle is fixedly located on the front wall of the movable groove and is attached to the lower end of the slider, the first support plate is located on the upper ends of both sides of the movable groove, and the limiting plate is located on the first support plate.

[0005] However, while existing injection molding waste crushing and recycling equipment can recycle and crush injection molding waste relatively well, the pre-impact crushing before the waste comes into contact with the crushing roller and the subsequent impact crushing after crushing are not very effective. This results in waste with inconsistent sizes, affecting the uniformity of the crushed particles due to the reliance on a single crushing roller. Furthermore, the conversion of the mechanical energy of the driving impact rod into wind energy is not high, and the delivery of the converted wind energy to the crushing frame is also low. This causes waste to adhere to the surface of the crushing roller, affecting its continuous use. Additionally, the synchronous cooling of the waste during crushing is not efficient, failing to meet user needs. Therefore, we propose a waste crushing and recycling device for injection molding. Summary of the Invention

[0006] To address the problems mentioned in the background, this invention provides a waste crushing and recycling device for injection molding, which solves the problems mentioned in the background art where the pre-impact crushing of injection molding waste before contact with the crushing roller is not very effective, and the further impact crushing after crushing is also not very effective, affecting the uniformity of the crushed particles. Furthermore, the conversion of the mechanical energy of the driving impact rod into wind energy is not very effective, affecting the cooling and adhesion of the waste during crushing.

[0007] To achieve the above-mentioned technical objectives, the technical solution adopted by the present invention is as follows: A waste crushing and recycling device for injection molding includes a main crushing frame, a receiving frame fixedly connected to the top of the main crushing frame, a conveying frame fixedly connected to the bottom of the main crushing frame, a secondary crushing frame fixedly connected to the bottom of the conveying frame, a crushing roller rotatably connected to the inner wall of the main crushing frame, and a rotary joint extending to the outside of the main crushing frame rotatably connected to the end of the crushing roller. A control box is fixedly connected to the outer wall of the main crushing frame. A worm gear is rotatably connected to the inner wall of the control box. A first connecting fan blade is fixedly connected to one end of the worm gear. A connecting cylinder sleeved on the outside of the first connecting fan blade is fixedly connected to the outer wall of the control box. An air supply pipe is fixedly connected to the outer wall of the connecting cylinder. A connecting pipe fixedly connected to the outer wall of the air supply pipe is fixedly connected to the outer wall of the rotary joint. A vent hole is opened on the surface of the crushing roller. The inner wall of the main crushing frame is rotatably connected to a fan plate located on one side of the crushing roller. The outer wall of the fan plate is fixedly connected to a striking rod. When processing injection molding waste through the crushing and recycling device, the striking rods are distributed on the upper and lower sides of the crushing roller, so that waste of different sizes is pre-crushed and re-crushed before and after crushing. At the same time, with the opening of the vent holes, the mechanical energy driving the fan plate is converted into wind energy for transportation, which prevents waste from adhering to the surface of the crushing roller and achieves the effect of simultaneous cooling of the waste. When the wind energy is transported into the crushing roller through the connecting pipe, in order to improve the acceleration effect of the wind energy before contacting the vent holes, the second connecting fan blade is driven to rotate by the wind energy. Under the connection of the second bevel gear set, the rotating shaft and the spiral roller are driven to rotate synchronously, which improves the wind speed through the vent holes for anti-sticking treatment.

[0008] Preferably, a drive box is fixedly connected to the outer wall of the main crushing frame, and a first motor is provided on the outer wall of the drive box. The output end of the first motor is fixedly connected to a drive gear that is fixedly connected to one end of the crushing roller.

[0009] Preferably, the drive gear is provided in two sets, and the two sets of drive gears are meshed with each other, and the rotation center of the drive gear is coincident with the rotation center of the crushing roller.

[0010] Preferably, the secondary crushing frame is provided with a crushing roller inside, and the crushing tooth density on the surface of the crushing roller inside the secondary crushing frame is greater than the crushing tooth density on the surface of the crushing roller inside the main crushing frame.

[0011] Preferably, the outer wall of the control box is provided with a second motor fixedly connected to one end of the worm gear, the outer wall of the worm gear is meshed with a worm wheel, and the rotation center of the worm wheel is fixedly connected to a first bevel gear set through a rotating shaft.

[0012] Preferably, the rotation center of the first bevel gear set coincides with the rotation center of the fan plate, and the outer wall of the worm is provided with two sets of spirals, which are arranged in opposite directions.

[0013] Preferably, the rotary joint has a second connecting fan blade located on one side of the connecting pipe, the rotation center of the second connecting fan blade is fixedly connected to a second bevel gear set, the outer wall of the second bevel gear set is fixedly connected to a rotating shaft, and the outer wall of the rotating shaft is fixedly connected to a spiral roller.

[0014] Preferably, the outer wall of the spiral roller is conical, the inner wall of the crushing roller is hollow, and the crushing roller is connected to the air supply pipe through a connecting pipe.

[0015] Preferably, a feeding frame is fixedly connected to the side wall of the conveying frame, a third motor is provided on the outer wall of the conveying frame, a swing rod is fixedly connected to the output end of the third motor, and a conversion plate is fixedly connected to the rotation center of the swing rod and rotatably connected to the inner side wall of the conveying frame. The rotation angle of the conversion plate can be controlled according to the crushing situation of the injection molding waste in the main crushing frame, so as to determine whether the crushed waste needs to be crushed again, thereby improving the effect of multiple crushing treatment of injection molding waste.

[0016] Preferably, a discharge port is provided at the connection between the outer wall of the conveying frame and the discharge frame, and a sliding column is fixedly connected to one end of the swing rod and slidably connected to the outer wall of the conveying frame. A limiting groove is provided at the connection between the outer wall of the conveying frame and the sliding column, and the outer wall contour of the limiting groove is arc-shaped.

[0017] Compared with the prior art, the beneficial effects of this invention are as follows: 1. The striking rod and vent holes provided in this invention enable the processing of injection molding waste materials through a crushing and recycling device. The striking rod is distributed on the upper and lower sides of the crushing roller, allowing waste materials of different sizes to undergo pre-crushing and re-crushing before and after crushing. At the same time, the opening of the vent holes allows the mechanical energy of the driving fan plate to be converted into wind energy for transportation, preventing waste materials from adhering to the surface of the crushing roller and achieving the effect of simultaneous cooling of the waste materials.

[0018] 2. The spiral roller provided in this invention can, when wind energy is transported into the crushing roller through the connecting pipe, drive the second connecting fan blade to rotate in order to improve the acceleration effect of wind energy before it comes into contact with the vent hole. Under the connection of the second bevel gear set, the rotating shaft and the spiral roller are driven to rotate synchronously, thereby improving the wind speed to pass through the vent hole for anti-sticking treatment.

[0019] 3. The conversion plate provided in this invention can control the rotation angle of the conversion plate according to the crushing situation of the injection molding waste in the main crushing frame, and determine whether the crushed waste needs to be crushed again, thereby improving the effect of multiple crushing treatment of injection molding waste. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the overall structure of the present invention; Figure 2 This is a schematic diagram of the overall side view structure of the present invention; Figure 3 This is a schematic diagram of the internal structure of the main crushing frame of the present invention; Figure 4 This is a schematic diagram of the internal structure of the drive box of the present invention; Figure 5 This is a schematic diagram of the positional distribution of the fan plate and the striking rod according to the present invention; Figure 6This is a schematic diagram of the first connecting fan blade position distribution structure of the present invention; Figure 7 This is a schematic diagram of the positional distribution of the gas delivery pipe and the crushing roller according to the present invention; Figure 8 For the present invention Figure 7 Enlarged structural diagram at point A in the diagram; Figure 9 This is a schematic diagram of the position distribution structure of the conversion plate of the present invention.

[0021] The labels in the attached diagram are: 1. Main crushing frame; 2. Receiving frame; 3. Conveying frame; 4. Secondary crushing frame; 5. Drive box; 6. First motor; 7. Crushing roller; 8. Drive gear; 9. Control box; 10. Worm gear; 11. First bevel gear set; 12. Fan plate; 13. Striking rod; 14. Connecting cylinder; 15. First connecting fan blade; 16. Air supply pipe; 17. Rotary joint; 18. Connecting pipe; 19. Second connecting fan blade; 20. Second bevel gear set; 21. Rotating shaft; 22. Spiral roller; 23. Vent hole; 24. Second motor; 25. Discharge frame; 26. Third motor; 27. Swing rod; 28. Sliding column; 29. ​​Limiting groove; 30. Conversion plate; 31. Worm gear. Detailed Implementation

[0022] To further illustrate the technical means and effects of the present invention in achieving its intended purpose, the following detailed description of the specific implementation methods, structures, features, and effects of the present invention, in conjunction with the accompanying drawings and preferred embodiments, is provided below.

[0023] Example 1: Please see Figures 1 to 9 This embodiment provides a waste crushing and recycling device for injection molding, including a main crushing frame 1, a receiving frame 2 fixedly connected to the top of the main crushing frame 1, a conveying frame 3 fixedly connected to the bottom of the main crushing frame 1, a secondary crushing frame 4 fixedly connected to the bottom of the conveying frame 3, a crushing roller 7 rotatably connected to the inner wall of the main crushing frame 1, and a rotary joint 17 extending to the outside of the main crushing frame 1 rotatably connected to the end of the crushing roller 7. A control box 9 is fixedly connected to the outer wall of the main crushing frame 1. A worm gear 31 is rotatably connected to the inner wall of the control box 9. A first connecting fan blade 15 is fixedly connected to one end of the worm gear 31. A connecting cylinder 14, sleeved outside the first connecting fan blade 15, is fixedly connected to the outer wall of the control box 9. An air supply pipe 16 is fixedly connected to the outer wall of the connecting cylinder 14. A connecting pipe 18, which is fixedly connected to the outer wall of the rotating joint 17, is fixedly connected to the outer wall of the air supply pipe 16. A vent hole 23 is provided on the surface of the crushing roller 7. A fan plate 12 located on one side of the crushing roller 7 is rotatably connected to the inner wall of the main crushing frame 1. A striking rod 13 is fixedly connected to the outer wall of the fan plate 12. A second motor 24, which is fixedly connected to one end of the worm gear 31, is provided on the outer wall of the control box 9. A worm wheel 10 meshes with the outer wall of the worm gear 31. A first bevel gear set 11 is fixedly connected to the rotation center of the worm wheel 10 through a rotating shaft. A second connecting fan blade 19, located on one side of the connecting pipe 18, is rotatably connected inside the rotating joint 17. The rotation center of blade 19 is fixedly connected to a second bevel gear set 20. The outer wall of the second bevel gear set 20 is fixedly connected to a rotating shaft 21. The outer wall of the rotating shaft 21 is fixedly connected to a spiral roller 22. When processing injection molding waste through the crushing and recycling device, the striking rods 13 are distributed on the upper and lower sides of the crushing roller 7, so that waste of different sizes is pre-crushed and re-crushed before and after crushing. At the same time, with the opening of the vent hole 23, the mechanical energy of the driving fan plate 12 is converted into wind energy for transportation, which prevents waste from adhering to the surface of the crushing roller 7 and achieves the effect of synchronous cooling of waste. When the wind energy is transported into the crushing roller 7 through the connecting pipe 18, in order to improve the acceleration effect of the wind energy before contacting the vent hole 23, the second connecting fan blade 19 is driven to rotate by the wind energy. Under the connection of the second bevel gear set 20, the rotating shaft 21 and the spiral roller 22 are synchronously driven to rotate, which improves the wind speed through the vent hole 23 for anti-sticking treatment.

[0024] like Figure 7 As shown, a drive box 5 is fixedly connected to the outer wall of the main crushing frame 1. A first motor 6 is installed on the outer wall of the drive box 5. A drive gear 8 is fixedly connected to one end of the crushing roller 7 at the output end of the first motor 6. There are two sets of drive gears 8, which mesh with each other. The rotation center of the drive gear 8 coincides with the rotation center of the crushing roller 7. The crushing roller 7 forms a rotating structure with the main crushing frame 1 through the first motor 6 and the drive gear 8, which is beneficial to the driving of the first motor 6. Through the connection of the drive gear 8, the crushing roller 7 is driven to rotate along the inner side wall of the main crushing frame 1 to efficiently crush the injection molding waste.

[0025] like Figure 6As shown, the secondary crushing frame 4 is equipped with a crushing roller 7 inside, and the crushing tooth density of the crushing roller 7 inside the secondary crushing frame 4 is greater than that of the crushing tooth density of the crushing roller 7 inside the main crushing frame 1. This is beneficial to achieve the effect of multiple crushing treatment of injection molding waste in the equipment by setting crushing rollers 7 with different surface crushing knife densities in the main crushing frame 1 and the secondary crushing frame 4.

[0026] like Figure 7 As shown, the rotation center of the first bevel gear set 11 coincides with the rotation center of the fan plate 12. The outer wall of the worm 31 is provided with two sets of spirals, which are arranged in opposite directions. The outer wall profile of the spiral roller 22 is conical, and the inner wall of the crushing roller 7 is hollow. The crushing roller 7 is connected to the air supply pipe 16 through the connecting pipe 18. This facilitates the effect of the airflow accelerating within the rotary joint 17 and penetrating the air vent 23 by the conical outer wall profile of the spiral roller 22.

[0027] like Figures 8-9 As shown, a feeding frame 25 is fixedly connected to the side wall of the conveying frame 3. A third motor 26 is installed on the outer wall of the conveying frame 3. A swing rod 27 is fixedly connected to the output end of the third motor 26. A conversion plate 30, which is rotatably connected to the inner side wall of the conveying frame 3, is fixedly connected to the rotation center of the swing rod 27. A feeding port is opened at the connection between the outer wall of the conveying frame 3 and the feeding frame 25. A sliding column 28, which is slidably connected to the outer wall of the conveying frame 3, is fixedly connected to one end of the swing rod 27. A limiting groove 29 is opened at the connection between the outer wall of the conveying frame 3 and the sliding column 28. The outer wall has an arc shape. The conversion plate 30 forms a flipping structure with the conveying frame 3 through the third motor 26 and the swing rod 27, which is conducive to the driving of the third motor 26. By rotating the swing rod 27, the conversion plate 30 is driven to flip along the inner side wall of the conveying frame 3, so that the conveying path of the crushed injection molding waste can be easily switched. The rotation angle of the conversion plate 30 can be controlled according to the crushing situation of the injection molding waste in the main crushing frame 1, and it can be determined whether the crushed waste needs to be crushed again, thereby improving the effect of multiple crushing treatment of injection molding waste.

[0028] Working principle: like Figure 1-9As shown, in use, the waste material crushing and recycling equipment for injection molding processes collects injection molding waste through the receiving frame 2. The waste is then conveyed by the receiving frame 2 to the main crushing frame 1. The first motor 6 outside the drive box 5 is activated, and the crushing roller 7 rotates under the drive gear 8, thus crushing the discharged injection molding waste. While the waste is being conveyed through the receiving frame 2 to the main crushing frame 1, the second motor 24 is activated, rotating the worm gear 31 and driving the worm wheel 10. The rotation of the worm wheel 10, through the connection of the first bevel gear set 11, drives the agitator plate 12 to rotate. With the action of the opposite spiral on the surface of the worm gear 31, the agitator plate 12 undergoes a relatively tumbling motion, simultaneously driving the striking rod 13 to undergo a relative tumbling motion. Pre-crushing treatment is performed on injection molding waste before crushing, and after crushing the waste, the crushed waste is crushed again by hammering to improve the multiple crushing treatment of waste in the crushing frame. When the drive worm 31 rotates continuously, it will drive the first connecting fan blade 15 to rotate synchronously. The generated gas is transported to the rotary joint 17 through the connection of the gas supply pipe 16 and the connecting pipe 18. Under the gas supply of the connecting pipe 18, the airflow acts on the second connecting fan blade 19 and drives the second connecting fan blade 19 to rotate. Under the connection of the rotating shaft 21, the spiral roller 22 is driven to rotate, so that the gas is accelerated to be transported into the crushing roller 7. The accelerated airflow flows out through the vent 23. The gas acts on the surface of the crushing roller 7 to prevent the waste from sticking during crushing and to perform synchronous cooling crushing treatment on the waste. After the injection molding waste is efficiently crushed, depending on the crushing condition, when the crushed waste needs to be discharged, the third motor 26 is turned on, and the rotation of the swing rod 27 drives the conversion plate 30 to rotate synchronously, so that the conversion plate 30 tilts along one side of the discharge frame 25, allowing the crushed waste to be discharged from the discharge frame 25. When the crushed waste needs to be crushed again, the conversion plate 30 tilts away from the discharge frame 25, so that the initially crushed waste is transported through the conversion plate 30 to the secondary crushing frame 4 for further crushing, achieving the effect of multiple crushing treatments of the injection molding waste and improving the efficiency of crushing treatment of injection molding waste in the recycling equipment.

[0029] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A waste crushing and recycling device for injection molding, comprising a main crushing frame (1), characterized in that: The top of the main crushing frame (1) is fixedly connected to a receiving frame (2), the bottom of the main crushing frame (1) is fixedly connected to a conveying frame (3), the bottom of the conveying frame (3) is fixedly connected to a secondary crushing frame (4), the inner wall of the main crushing frame (1) is rotatably connected to a crushing roller (7), and the end of the crushing roller (7) is rotatably connected to a rotary joint (17) extending to the outside of the main crushing frame (1). The outer wall of the main crushing frame (1) is fixedly connected to a control box (9), the inner wall of the control box (9) is rotatably connected to a worm gear (31), one end of the worm gear (31) is fixedly connected to a first connecting fan blade (15), the outer wall of the control box (9) is fixedly connected to a connecting cylinder (14) sleeved outside the first connecting fan blade (15), the outer wall of the connecting cylinder (14) is fixedly connected to an air supply pipe (16), the outer wall of the air supply pipe (16) is fixedly connected to a connecting pipe (18) fixedly connected to the outer wall of the rotary joint (17), and the surface of the crushing roller (7) is provided with a vent hole (23). The inner wall of the main crushing frame (1) is rotatably connected to a fan plate (12) located on one side of the crushing roller (7), and the outer wall of the fan plate (12) is fixedly connected to a striking rod (13).

2. The waste crushing and recycling device for injection molding as described in claim 1, characterized in that: The outer wall of the main crushing frame (1) is fixedly connected to a drive box (5), and the outer wall of the drive box (5) is provided with a first motor (6). The output end of the first motor (6) is fixedly connected to a drive gear (8) that is fixedly connected to one end of the crushing roller (7).

3. The waste crushing and recycling device for injection molding as described in claim 2, characterized in that: The drive gear (8) is provided in two sets, and the two sets of drive gears (8) are meshed with each other. The rotation center of the drive gear (8) and the rotation center of the crushing roller (7) are coincident.

4. The waste crushing and recycling device for injection molding as described in claim 1, characterized in that: The secondary crushing frame (4) is equipped with a crushing roller (7), and the crushing tooth density on the surface of the crushing roller (7) inside the secondary crushing frame (4) is greater than the crushing tooth density on the surface of the crushing roller (7) inside the main crushing frame (1).

5. The waste crushing and recycling device for injection molding as described in claim 1, characterized in that: The outer wall of the control box (9) is provided with a second motor (24) fixedly connected to one end of the worm (31). The outer wall of the worm (31) is meshed with a worm wheel (10). The rotation center of the worm wheel (10) is fixedly connected to a first bevel gear set (11) through a rotating shaft.

6. The waste crushing and recycling device for injection molding as described in claim 5, characterized in that: The rotation center of the first bevel gear set (11) coincides with the rotation center of the fan plate (12), and the outer wall of the worm (31) is provided with two sets of spirals, which are arranged in opposite directions.

7. The waste crushing and recycling device for injection molding as described in claim 1, characterized in that: The rotary joint (17) is internally rotatably connected to a second connecting fan blade (19) located on one side of the connecting pipe (18). The rotation center of the second connecting fan blade (19) is fixedly connected to a second bevel gear set (20). The outer wall of the second bevel gear set (20) is fixedly connected to a rotating shaft (21). The outer wall of the rotating shaft (21) is fixedly connected to a spiral roller (22).

8. The waste crushing and recycling device for injection molding as described in claim 7, characterized in that: The outer wall of the spiral roller (22) is conical, the inner wall of the crushing roller (7) is hollow, and the crushing roller (7) is connected to the gas supply pipe (16) through the connecting pipe (18).

9. The waste crushing and recycling device for injection molding as described in claim 1, characterized in that: The side wall of the conveying frame (3) is fixedly connected to a feeding frame (25), and the outer wall of the conveying frame (3) is provided with a third motor (26). The output end of the third motor (26) is fixedly connected to a swing rod (27), and the rotation center of the swing rod (27) is fixedly connected to a conversion plate (30) that is rotatably connected to the inner side wall of the conveying frame (3).

10. A waste crushing and recycling device for injection molding as described in claim 9, characterized in that: The outer wall of the conveying frame (3) and the connection part of the feeding frame (25) are provided with a feeding port. One end of the swing rod (27) is fixedly connected to a sliding column (28) that is slidably connected to the outer wall of the conveying frame (3). A limiting groove (29) is provided at the connection part of the outer wall of the conveying frame (3) and the sliding column (28), and the outer wall contour of the limiting groove (29) is arc-shaped.

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