A multi-stand y-type aluminum alloy bar rolling device

Abstract

The present application relates to the technical field of metal rolling, in particular to a multi-stand Y-shaped aluminum alloy bar rolling equipment, comprising four groups of integrated rolling mills and two groups of single-drive rolling mills arranged in a line and connected horizontally, the integrated rolling mills and the single-drive rolling mills are of the same structure, the four groups of integrated rolling mills are butt-jointed at the head and tail, a connecting mechanism is installed between every two adjacent groups of integrated rolling mills, a limiting Y-ring is arranged on the connecting mechanism to limit the bar and prevent burrs, the two groups of single-drive rolling mills are also connected by a connecting mechanism, the rear sides of the four groups of integrated rolling mills and the two groups of single-drive rolling mills are driven to rotate by driving mechanisms, which is conducive to reducing the probability of stand stall, the two groups of single-drive rolling mills are separately driven by single-drive components, which is conducive to rounding of various specifications, compensation for long-term wear and tear, making the pass more close to the design value, the three-roller Y-shaped rolling mill has large rolling pressure, high torque, adjustable pass, is not easy to produce ears during rolling, and rounding is more accurate.

Description

Technical Field

[0001] This invention relates to the field of metal rolling technology, specifically to a multi-stand Y-shaped aluminum alloy bar rolling equipment. Background Technology

[0002] Aluminum alloy bars have a wide range of applications in modern industrial systems. They can be used for machining equipment such as couplings, or for forging components with high performance requirements such as control arms. Traditional aluminum alloy extruded bars are generally manufactured by extrusion. Aluminum alloy extrusion generally involves feeding heated bars into an extrusion cylinder, and then extruding them through a die under the action of an extrusion rod to obtain the required bars.

[0003] For example, CN115945518A discloses a three-roll mill stand and a three-roll mill with a roll balancing device. The three-roll mill stand includes an inner frame containing two side plates spaced apart front to back. Three roll units are arranged between the two side plates. Each roll unit contains a roll assembly and a roll balancing device. When the roll assembly is subjected to pressure pointing towards the rolling centerline, the roll balancing device provides a reaction force to the roll assembly. This three-roll mill stand avoids the problem of the three roll centers not perfectly aligning with the stand center within the adjustment range, common with lever-type roll stands. It also solves the problem that vertically pressing roll stands are unsuitable for lateral roll changing and have complex roll changing operations. It features a simple and reasonable structure, convenient operation and maintenance, low cost, and high safety and reliability.

[0004] While existing rolling mills can meet the requirements of use, the yield of aluminum alloy bars produced by this method is generally only about 75% due to limitations in die length, extrusion pressure, and extrusion process. Moreover, the slow extrusion speed and the friction between the bar and the die, and between the bar and the extrusion cylinder, can easily lead to uneven deformation of the internal structure of the bar, resulting in uneven product structure and properties, which affects the final performance of the product. Summary of the Invention

[0005] The purpose of this invention is to provide an aluminum alloy bar rolling apparatus that can realize the rapid rolling of aluminum alloy bars.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a multi-stand Y-shaped aluminum alloy bar rolling equipment, comprising four integrated rolling mills and two single-drive rolling mills arranged in a row and connected laterally. The integrated rolling mills and the single-drive rolling mills have the same structure. The four integrated rolling mills are connected end to end. A connecting mechanism is installed between adjacent integrated rolling mills. The connecting mechanism is provided with a limiting Y-ring to limit the bar and prevent flash. Adjacent single-drive rolling mills are also connected by a connecting mechanism. The rear sides of the four integrated rolling mills and the two single-drive rolling mills are all driven by a drive mechanism.

[0007] Preferably, the single integrated rolling mill includes a front docking shell and a rear docking shell, the front docking shell and the rear docking shell have the same structure, the front docking shell and the rear docking shell are connected and installed together, a rolling mechanism is installed at the center of the front docking shell and the rear docking shell, three sets of positioning rings are fixed in an inverted triangular shape on the outer wall of the front docking shell and the rear docking shell, and connecting blocks are fixed on the front and rear sides of the front docking shell and the rear docking shell.

[0008] Preferably, the top of the front docking shell is provided with a lifting lug, the center of the front docking shell is provided with a circular cavity, and the sides of the circular cavity are provided with three sets of U-shaped cavities in a Y-shape.

[0009] Preferably, the rolling mechanism includes a main rotating shaft and a connecting shaft. The main rotating shaft is horizontally installed at the center of the U-shaped cavity at the top. The connecting shaft is fixed at the rear end of the main rotating shaft. A main roll is fixed at the center of the main rotating shaft. Main bevel gears are fixed on both sides of the main roll. The bottom ends of the two sets of main bevel gears respectively mesh with secondary bevel gears. The two sets of secondary bevel gears are respectively fixed on the upper side of the corresponding secondary rotating shafts. The two sets of secondary rotating shafts are obliquely installed inside the other two sets of U-shaped cavities. A secondary roll is fixed at the center of the two sets of secondary rotating shafts. The two sets of secondary rolls and the main roll are Y-shaped. Y-shaped mounting brackets are provided at the front and rear ends of the rolling mechanism for limiting and fixing.

[0010] Preferably, an internal gear is installed at the rear end of the connecting shaft, and four sets of mating holes are opened on the outer wall of the internal gear. The main bevel gear and the auxiliary bevel gear are lubricated with emulsion, and the main shaft and the auxiliary shaft are sealed in the front mating shell and lubricated with grease.

[0011] Preferably, the connecting mechanism includes a limiting Y-ring and a connecting pin. The two ends of the limiting Y-ring are respectively inserted into three sets of positioning rings on the corresponding sides, and the connecting pin is installed on the connecting blocks on the adjacent two sets of rolling mill sides.

[0012] Preferably, the limiting Y-ring includes a hollow ring and three sets of extension plates. The diameter of the hollow ring is larger than the diameter of the rod. Three sets of extension plates are fixed to the side of the hollow ring, and a connecting post is fixed to the top of each of the three sets of extension plates.

[0013] Preferably, the drive mechanism includes a drive box, a main drive unit, and two sets of individual drive units. A pad is fixed at the rear end of the drive box, and two sets of individual drive units are installed on the upper side of the pad. The main drive unit is installed at the front end of the drive box.

[0014] Preferably, the main drive unit includes a main motor and a drive rod. The main motor drives the drive rod, which is installed in the drive housing, to rotate. Four sets of worm gears are installed at the center of the drive rod. Each of the four sets of worm gears has a main drive component on its upper side. The center of each of the four sets of main drive components is installed on the front wall of the drive housing. Worm wheels are fixed at the rear ends of each of the four sets of main drive components. The bottom ends of the worm wheels mesh with the worm gears. The single drive unit includes an auxiliary motor and auxiliary drive components. Two sets of auxiliary drive components are installed on the left side of the front wall of the drive housing. The auxiliary drive components are directly driven by the auxiliary motor. The auxiliary drive components have the same structure as the main drive components.

[0015] Preferably, the main drive component in a single set includes a drive shaft, a limiting bearing, and a fixed bearing. The fixed bearing is installed on the front wall of the drive housing. The drive shaft is located at the center of the fixed bearing. The limiting bearing is located at the rear end of the drive shaft. The limiting bearing is installed on the inner rear wall of the drive housing. Four sets of docking posts are fixed at the front end of the drive shaft. The four sets of docking posts can engage with four sets of docking holes opened in the internal gear.

[0016] Compared with the prior art, the beneficial effects of the present invention are:

[0017] 1. The four integrated rolling mills use a central drive unit for centralized transmission, which helps reduce the probability of stand stall. The two single-drive rolling mills use individual drive units for separate transmission, which facilitates rounding of various specifications. Furthermore, the adjustable motor speed and tension improve the applicability of the device. The two sets of main bevel gears and main rolls and the two sets of auxiliary bevel gears and auxiliary rolls in the rolling mechanism are designed in a Y shape. The two sets of bevel gears mesh with each other to improve the compensation for wear and tear over long-term use, making the pass shape closer to the design value. The three-roll Y-type rolling mill has high rolling pressure, high torque, adjustable pass shape, less tendency to produce earing during rolling, more accurate rounding, and simple structure.

[0018] 2. By using a design where both the main bevel gear and the auxiliary bevel gear have a larger diameter than the fixed main and auxiliary shafts, the service life can be improved, the torque can be increased, and the production efficiency can be improved. The roll gap size or rolling center can be adjusted by two sets of auxiliary shafts with an adjustment amount of about 1.5mm, which can improve the compensation for wear and tear over long-term use and make the roll pass closer to the design value. The main drive unit in the main drive unit can synchronously drive four sets of integrated rolling mills to operate, thereby improving efficiency.

[0019] 3. The limiting Y-ring between two adjacent sets of rolling mills can reduce the distance between them. The inner diameter of the hollow ring in the limiting Y-ring is larger than the diameter of the bar, which can effectively prevent the bar from deflecting and twisting during transportation, prevent flash, and improve stability. The extension plate and connecting column on the side of the hollow ring can effectively connect to the center of the two sets of rolling mills, thereby improving the positioning effect, saving installation time, and facilitating use. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 This is a side view of the main structure of the present invention;

[0022] Figure 2 This is a front view schematic diagram of the main structure of the present invention;

[0023] Figure 3 This is a top view of the main structure of the present invention;

[0024] Figure 4 This is a front view schematic diagram of the installation of the two integrated rolling mills according to the present invention;

[0025] Figure 5 This is a front view schematic diagram of the two sets of integrated rolling mills of the present invention separated;

[0026] Figure 6 This is a schematic diagram of the disassembly of a single integrated rolling mill according to the present invention;

[0027] Figure 7 This is a rear view schematic diagram of the integrated rolling mill of the present invention;

[0028] Figure 8 This is a rear cross-sectional view of the drive mechanism of the present invention;

[0029] Figure 9 This is a side cross-sectional view of the main drive component structure of the present invention.

[0030] In the diagram: 1. Integrated rolling mill; 11. Front docking shell; 111. Lifting lug; 112. Circular cavity; 113. U-shaped cavity; 12. Rear docking shell; 13. Rolling mechanism; 131. Main shaft; 132. Connecting shaft; 1321. Internal gear; 1322. Docking hole; 133. Main roll; 134. Main bevel gear; 135. Auxiliary bevel gear; 136. Auxiliary roll; 137. Auxiliary shaft; 138. Y-shaped mounting bracket; 14. Positioning ring; 15. Connecting block; 2. Single-drive rolling mill; 3. Connecting mechanism 31. Limiting Y-ring; 311. Hollow ring; 312. Extension plate; 313. Connecting column; 32. Connecting pin; 4. Drive mechanism; 41. Drive box; 411. Pad block; 42. Main drive component; 421. Main motor; 422. Drive rod; 423. Worm gear; 424. Main drive component; 4241. Transmission shaft; 4242. Limiting bearing; 4243. Fixed bearing; 4244. Connecting column; 425. Worm gear; 43. Single drive component; 431. Auxiliary motor; 432. Auxiliary drive component. Detailed Implementation

[0031] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0032] Please see Figures 1-9 The present invention provides an embodiment of a multi-stand Y-shaped aluminum alloy bar rolling equipment, comprising four integrated rolling mills 1 and two single-drive rolling mills 2 arranged in a row and connected laterally. The integrated rolling mills 1 and the single-drive rolling mills 2 have the same structure. The four integrated rolling mills 1 are connected end to end. A connecting mechanism 3 is installed between two adjacent integrated rolling mills 1. The connecting mechanism 3 is provided with a limiting Y-ring 31 to limit the bar and prevent flash. The two adjacent single-drive rolling mills 2 are also connected by a connecting mechanism 3. The rear sides of the four integrated rolling mills 1 and the two single-drive rolling mills 2 are all driven by a driving mechanism 4.

[0033] As a further aspect of the present invention, the single-unit integrated rolling mill 1 includes a front docking shell 11 and a rear docking shell 12. The front docking shell 11 and the rear docking shell 12 have the same structure and are installed together. A rolling mechanism 13 is installed at the center of the front docking shell 11 and the rear docking shell 12. Three sets of positioning rings 14 are fixed in an inverted triangular shape on the outer wall of the front docking shell 11 and the rear docking shell 12. Connecting blocks 15 are fixed on the front and rear sides of the front docking shell 11 and the rear docking shell 12. A lifting lug 111 is opened at the top of the front docking shell 11. A circular cavity 112 is opened in the center of the front docking shell 11. Three sets of U-shaped cavities 113 are opened in a Y-shape on the side of the circular cavity 112. This design is beneficial for the rapid installation of the rolling mill and improves efficiency. The three sets of U-shaped cavities facilitate the installation of the rolling mechanism, thereby better processing the bar stock.

[0034] As a further development of the present invention, the rolling mechanism 13 includes a main rotating shaft 131 and a connecting shaft 132. The main rotating shaft 131 is horizontally installed at the center of the U-shaped cavity 113 at the top. The connecting shaft 132 is fixed at the rear end of the main rotating shaft 131. A main roll 133 is fixed at the center of the main rotating shaft 131. Main bevel gears 134 are fixed on both sides of the main roll 133. The bottom ends of the two sets of main bevel gears 134 respectively mesh with secondary bevel gears 135. The two sets of secondary bevel gears 135 are respectively fixed on the upper side of the corresponding secondary rotating shafts 137. The two sets of secondary rotating shafts 137 are obliquely installed inside the other two sets of U-shaped cavities 113. A secondary roll 136 is fixed at the center of the two sets of secondary rotating shafts 137. The auxiliary roll 136 and the main roll 133 are Y-shaped. The front and rear ends of the rolling mechanism 13 are equipped with Y-shaped mounting brackets 138 for limiting and fixing. The rear end of the connecting shaft 132 is equipped with an internal gear 1321. The outer wall of the internal gear 1321 has four sets of docking holes 1322. The main bevel gear 134 and the auxiliary bevel gear 135 are lubricated with emulsion. The main shaft 131 and the auxiliary shaft 137 are sealed in the front docking shell 11 and lubricated with grease. The above design can reduce the probability of frame stall and improve stability. At the same time, the three-roll Y-type rolling mill has high rolling pressure, high torque, adjustable pass shape, less earing during rolling, more accurate rounding, and simple structure.

[0035] Furthermore, the connecting mechanism 3 includes a limiting Y-ring 31 and a connecting pin 32. The two ends of the limiting Y-ring 31 are respectively inserted into the three sets of positioning rings 14 on the corresponding sides. The connecting pin 32 is installed on the connecting blocks 15 on the adjacent two sets of rolling mill sides. The limiting Y-ring 31 includes a hollow ring 311 and three sets of extension plates 312. The diameter of the hollow ring 311 is larger than the diameter of the bar. Three sets of extension plates 312 are fixed on the side of the hollow ring 311. A connecting post 313 is fixed at the top of each of the three sets of extension plates 312. Through the above design, the bar can be effectively prevented from deflecting and twisting during transportation, and the flash can be prevented to improve stability.

[0036] As a further improvement of the present invention, the drive mechanism 4 includes a drive housing 41, a main drive component 42, and two sets of individual drive components 43. A pad 411 is fixedly provided at the rear end of the drive housing 41, and two sets of individual drive components 43 are mounted on the upper side of the pad 411. The main drive component 42 is mounted at the front end of the drive housing 41. The main drive component 42 includes a main motor 421 and a drive rod 422. The main motor 421 drives the drive rod 422 installed in the drive housing 41 to rotate. Four sets of worm gears 423 are mounted at the center of the drive rod 422, and a main drive component 424 is provided on the upper side of each of the four sets of worm gears 423. The center of drive unit 424 is installed on the front wall of drive box 41. The rear end of the four main drive units 424 is fixed with worm gears 425. The bottom ends of the four worm gears 425 mesh with worms 423. The single drive unit 43 includes an auxiliary motor 431 and an auxiliary drive unit 432. The two auxiliary drive units 432 are installed on the left side of the front wall of drive box 41. The auxiliary drive units 432 are directly driven by the auxiliary motor 431. The auxiliary drive units 432 have the same structure as the main drive units 424. Through the above design, the four integrated rolling mills can be synchronously driven, thereby further improving the stability during operation and improving the operating efficiency of the equipment.

[0037] Furthermore, the single main drive unit 424 includes a drive shaft 4241, a limit bearing 4242, and a fixed bearing 4243. The fixed bearing 4243 is installed on the front wall of the drive box 41. The drive shaft 4241 is located at the center of the fixed bearing 4243. The limit bearing 4242 is located at the rear end of the drive shaft 4241. The limit bearing 4242 is installed on the inner rear wall of the drive box 41. Four sets of docking posts 4244 are fixed at the front end of the drive shaft 4241. The four sets of docking posts 4244 can be engaged with the four sets of docking holes 1322 opened in the internal gear 1321. This design facilitates connection to the transmission rolling mill, thereby improving transmission.

[0038] Working principle: During operation, when installing four sets of integrated rolling mills 1 and two sets of single-drive rolling mills 2, a limiting Y-ring 31 can be placed at the central connection position first. Then, push one side of the three sets of connecting columns 313 fixed at the top of the three sets of extension plates 312 in the limiting Y-ring 31 to the positioning ring 14 fixed on the side of one rolling mill. After installation, the other side of the three sets of connecting columns 313 can be mated and fitted into the corresponding three sets of positioning rings 14. Simultaneously, two adjacent sets of rolling mills can be installed and fixed via connecting pins 32 and connecting blocks 15. Then, the main motor 421 drives the drive rod 422 to rotate within the drive box 41. The rotation of the drive rod 41 drives the four sets of worm gears 423 fixed at the center to rotate. The rotation of the worm gears 423 meshes with the worm wheel 425 at the top, and the rotation of the worm wheel 425 drives the transmission shaft 4241 to rotate between the limiting bearing 4242 and the fixed bearing. The drive shaft 4241 rotates within the four sets of docking posts 4244 fixed at the front end, which in turn rotate within the four sets of docking holes 1322 on the rear wall of the connecting shaft 132. The drive shaft 4241 drives the connecting shaft 132 to rotate, which in turn drives the internal main rotating shaft 131 to rotate. The rotation of the main rotating shaft 131 drives the centrally fixed main roll 133 and the main bevel gears 134 on both sides to rotate. When the main bevel gears 134 on both sides rotate, they can also drive the auxiliary bevel gears 135 on both sides to rotate. When the auxiliary bevel gears 135 rotate, they can drive the centrally fixed auxiliary rotating shaft 137 to rotate within the U-shaped cavity 113. The rotation of the auxiliary rotating shaft 137 drives the central auxiliary roll 136 to rotate. The rotation of the two sets of auxiliary rolls 136 and the main roll 133 can drive the bar to be conveyed and rolled, thereby improving the rolling efficiency.

[0039] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Those skilled in the art can readily implement the present invention based on the accompanying drawings and the above description. However, any modifications, alterations, or variations made by those skilled in the art without departing from the scope of the present invention, utilizing the disclosed technical content, are equivalent embodiments of the present invention. Furthermore, any modifications, alterations, or variations made to the above embodiments based on the essential technology of the present invention are still within the protection scope of the present invention.

Claims

1. A multi-stand Y-shaped aluminum alloy bar rolling equipment, comprising four integrated rolling mills (1) and two single-drive rolling mills (2) arranged in a straight line and connected laterally, characterized in that: The integrated rolling mill (1) has the same structure as the single-drive rolling mill (2). The four sets of integrated rolling mills (1) are connected end to end. A connecting mechanism (3) is installed between two adjacent sets of integrated rolling mills (1). The connecting mechanism (3) has a limiting Y-ring (31) to limit the bar and prevent flash. The two adjacent sets of single-drive rolling mills (2) are also connected by a connecting mechanism (3). The rear sides of the four sets of integrated rolling mills (1) and the two sets of single-drive rolling mills (2) are driven by a driving mechanism (4). Each set of integrated rolling mills (1) includes a front docking shell (11) and a rear docking shell (12). The front docking shell (11) and the rear docking shell (12) have the same structure. The front docking shell (11) and the rear docking shell (12) are connected by a connecting mechanism (3). The shells (12) are connected and installed together. A rolling mechanism (13) is installed at the center of the front docking shell (11) and the rear docking shell (12). Three sets of positioning rings (14) are fixed in an inverted triangular shape on the outer walls of the front docking shell (11) and the rear docking shell (12). Connecting blocks (15) are fixed on the front and rear sides of the front docking shell (11) and the rear docking shell (12). A lifting lug (111) is opened at the top of the front docking shell (11). A circular cavity (112) is opened in the center of the front docking shell (11). Three sets of U-shaped cavities (113) are opened in a Y shape on the side of the circular cavity (112). The rolling mechanism (13) includes a main rotating shaft (131) and a connecting shaft (132). The main rotating shaft (131) is water A connecting shaft (132) is fixedly mounted at the rear end of the main rotating shaft (131) in the center of the top U-shaped cavity (113). A main roller (133) is fixedly mounted at the center of the main rotating shaft (131). Main bevel gears (134) are fixedly mounted on both sides of the main roller (133). The bottom ends of the two sets of main bevel gears (134) respectively mesh with auxiliary bevel gears (135). The two sets of auxiliary bevel gears (135) are respectively fixed on the upper side of the corresponding auxiliary rotating shafts (137). The two sets of auxiliary rotating shafts (137) are installed obliquely inside the other two sets of U-shaped cavities (113). A secondary roller (136) is fixedly mounted at the center of the two sets of auxiliary rotating shafts (137). The two sets of auxiliary rollers (136) and the main roller (133) are perpendicular to each other. Y-shaped, the front and rear ends of the rolling mechanism (13) are provided with Y-shaped mounting brackets (138) for limiting and fixing, the connecting mechanism (3) includes a limiting Y ring (31) and a connecting pin (32), the two ends of the limiting Y ring (31) are respectively inserted into the three sets of positioning rings (14) on the corresponding sides, the connecting pin (32) is installed on the connecting blocks (15) on the side of the adjacent two sets of rolling mills, the limiting Y ring (31) includes a hollow ring (311) and three sets of extension plates (312), the diameter of the hollow ring (311) is larger than the diameter of the bar, the side of the hollow ring (311) is fixed with three sets of extension plates (312), and the top of the three sets of extension plates (312) is fixed with a connecting column (313).

2. The multi-stand Y-shaped aluminum alloy bar rolling equipment according to claim 1, characterized in that: An internal gear (1321) is installed at the rear end of the connecting shaft (132). Four sets of mating holes (1322) are opened on the outer wall of the internal gear (1321). The main bevel gear (134) and the auxiliary bevel gear (135) are lubricated with emulsion. The main shaft (131) and the auxiliary shaft (137) are sealed in the front mating shell (11) and lubricated with grease.

3. The multi-stand Y-shaped aluminum alloy bar rolling equipment according to claim 1, characterized in that: The drive mechanism (4) includes a drive box (41), a main drive component (42) and two sets of single drive components (43). A pad (411) is fixedly provided at the rear end of the drive box (41). Two sets of single drive components (43) are installed on the upper side of the pad (411). The main drive component (42) is installed at the front end of the drive box (41).

4. The multi-stand Y-shaped aluminum alloy bar rolling equipment according to claim 3, characterized in that: The main drive unit (42) includes a main motor (421) and a drive rod (422). The main motor (421) drives the drive rod (422) installed in the drive box (41) to rotate. Four sets of worm gears (423) are installed at the center of the drive rod (422). A main drive unit (424) is provided on the upper side of each of the four sets of worm gears (423). The center of the four sets of main drive units (424) is installed on the front wall of the drive box (41). A worm wheel (425) is fixed at the rear end of the four sets of main drive units (424). The bottom end of the four sets of worm wheels (425) meshes with the worm gear (423). The single drive unit (43) includes an auxiliary motor (431) and an auxiliary drive unit (432). Two sets of auxiliary drive units (432) are installed on the left side of the front wall of the drive box (41). The auxiliary drive unit (432) is directly driven by the auxiliary motor (431). The auxiliary drive unit (432) has the same structure as the main drive unit (424).

5. The multi-stand Y-shaped aluminum alloy bar rolling equipment according to claim 4, characterized in that: The single main drive unit (424) includes a drive shaft (4241), a limiting bearing (4242), and a fixed bearing (4243). The fixed bearing (4243) is installed on the front wall of the drive box (41). The drive shaft (4241) is located at the center of the fixed bearing (4243). The limiting bearing (4242) is located at the rear end of the drive shaft (4241). The limiting bearing (4242) is installed on the inner rear wall of the drive box (41). Four sets of docking posts (4244) are fixed at the front end of the drive shaft (4241). The four sets of docking posts (4244) can engage with the four sets of docking holes (1322) opened by the internal gear (1321).

Images