Unified adjusting mechanism for end faces of bearing rings

Abstract

The invention provides a bearing ring end face unified adjusting mechanism, and relates to the technical field of bearing machining. A conveying belt A is fixedly mounted at the front end of the top of the base, an adjusting frame is fixedly mounted on the right side of the top of the conveying belt A, a threaded hole is formed in the right side of the adjusting frame, and a screw A is rotationally connected into the threaded hole of the adjusting frame. The turn-over adjusting link is achieved through the combined action of the arc-shaped slopes at the two ends of the left side of the triangular limiting piece and the pressing blocks at the arc-shaped positions of the guide plate A and the guide plate B without the help of a complex device, the manufacturing cost is reduced, meanwhile, equipment shutdown caused by faults of complex parts is reduced, and the equipment operation stability is improved. The problems that part of devices are complex in structure, the turn-over adjusting link depends on cooperation of various precise and complex parts, the manufacturing cost is increased, the failure rate of equipment is increased, once a certain part goes wrong, the whole device can not normally operate, and the production schedule is affected are solved.

Description

Technical Field

[0001] This invention relates to the field of bearing processing technology, and in particular to a bearing ring end face uniform adjustment mechanism. Background Technology

[0002] Bearing rings are ring-shaped parts of radial rolling bearings with one or more raceways. After initial forming, bearing rings need to be precision-machined, including rough grinding and fine grinding on a grinding machine. To facilitate subsequent processing, the bearing rings need to be flipped to ensure that the bearing rings face the same direction, thereby improving the efficiency of subsequent processing.

[0003] Application number CN201810366360.1 discloses an automatic bearing ring flipping processing device, including a frame, a feeder, a tool holder, and a fixed chuck. This invention combines the frame, feeder, tool holder, and fixed chuck together. Through testing and optimization, the grinding chuck, in conjunction with the automatic ejector rod, facilitates the clamping and ejection of the bearing rings. The lifting rail, electric slider, storage box, and feed pipe work together to ensure accurate and continuous supply of bearing rings. The horizontal indexer and feeding ring work together to flip the bearing rings, which are then pushed into the grinding chuck by a pusher. The lifting cylinder at the top of the lifting tool holder can move the lifting top plate horizontally or at a certain angle, facilitating multi-tool operation. This invention enables the processing device to automatically feed and process bearings in multiple stages, and can also perform flipping and reprocessing after processing one side. The process is continuous, with small errors and high production efficiency.

[0004] Based on the above patent searches and understanding of the application of existing bearing ring end face flipping: 1. Some parts of the equipment have complex structures, and the flipping and adjustment process relies on the cooperation of a variety of precision and complex components, which not only increases manufacturing costs but also increases the failure rate of the equipment. If a component fails, the entire equipment may not be able to operate normally, affecting the production schedule. 2. When adjusting bearing rings of different specifications, the adaptability is poor. It is difficult to make quick and accurate adjustments based on the size and other parameters of the bearing rings. It requires a lot of time for equipment debugging, which reduces production efficiency. 3. Some devices lack an effective cleaning mechanism during the conveying and adjustment of bearing rings, and dust and impurities are easily left on the surface of the bearing rings. These impurities may adversely affect the accuracy and quality of the bearing rings in subsequent processing.

[0005] 4. During the conveying process, bearing rings may experience positional shifts. Some existing devices lack an effective centering adjustment mechanism, resulting in inconsistent positions of the bearing rings when they enter subsequent processing stages, affecting the accuracy and consistency of the processing.

[0006] Therefore, in view of this, we have studied and improved the existing structure and its shortcomings, and provided a unified adjustment mechanism for the end face of the bearing ring, in order to achieve a more practical purpose. Summary of the Invention

[0007] This invention provides a bearing ring end face uniform adjustment mechanism, specifically including: a base; a conveyor belt A is fixedly installed at the top front end of the base, an adjustment frame is fixedly installed at the top right side of the conveyor belt A, a threaded hole is opened at the right side of the adjustment frame, and a screw A is rotatably connected in the threaded hole of the adjustment frame; a progressive frame is slidably connected inside the adjustment frame, the middle right side of the progressive frame is rotatably connected to the left side of the screw A, a threaded hole is opened at the top of the progressive frame, and a screw B is rotatably connected in the threaded hole of the progressive frame; a triangular limiting member is slidably connected inside the progressive frame, the top of the triangular limiting member is rotatably connected to the bottom of the screw B, the left ends of the triangular limiting member are arc-shaped, the lower left side of the adjustment frame is fixedly connected to the lower right side of the slope frame, the slope frame is located directly to the left of the triangular limiting member, and a baffle is provided on the left side of the slope frame.

[0008] Furthermore, a pad is fixedly installed at the top right center of the base, a conveyor belt B is fixedly installed at the top of the pad, adjustable spacing limit bars are provided on both sides of the top of the conveyor belt B, and a bearing kit is placed at the rear of the conveyor belt B.

[0009] Furthermore, a fan is fixedly installed at the top center of the conveyor belt B, and a vacuum cleaner is fixedly installed at the top front center of the conveyor belt B. The vacuum cleaner is located at the front end of the fan, and an arc-shaped guide is provided at the front end of the conveyor belt B, which is located above the conveyor belt A.

[0010] Furthermore, the upper left side of the slope frame is located below and in front of conveyor belt B, the top of the slope frame has a left-high-right-low structure design, and the internal slope of the slope frame is equipped with guide rails.

[0011] Furthermore, the right side of the guide rail is fixedly connected to the left side of the triangular guide platform, the bottom of the triangular guide platform is fixedly connected to the right side of the top of the slope frame, and the triangular guide platform is located below the triangular limiting component.

[0012] Furthermore, a side plate is provided at the front and rear ends of the top of the slope frame, and threaded holes are provided on both sides of the middle of each side plate. An adjusting bolt A is rotatably connected in the threaded hole of the front side plate. The inner side of the two adjusting bolts A is rotatably connected to the outer side of the guide plate A. The guide plate A is located in the middle front of the two side plates. The bottom of the guide plate A corresponds to the front end of the top of the slope frame, and the right side of the guide plate A is arc-shaped. A pressure block is provided at the arc-shaped right side of the guide plate A. The arc-shaped right side of the guide plate A corresponds to the arc-shaped front end of the triangular limiting member.

[0013] Furthermore, an adjusting bolt B is rotatably connected in the threaded hole of the side plate at the rear end of the slope frame. The inner positions of the two adjusting bolts B are rotatably connected to the outer positions of the guide plate B. The guide plate B is located in the middle rear position of the two side plates, and the guide plate B and guide plate A are symmetrically designed. The bottom position of the guide plate B corresponds to the rear end of the top of the slope frame, and the right side of the guide plate B is arc-shaped. A pressure block is provided at the arc-shaped right side of the guide plate B. The arc-shaped right side of the guide plate B corresponds to the arc-shaped rear end of the triangular limiting member. The left side of the guide plate B bends backward, and the bent left side of the guide plate B is located at the right rear of the arc-shaped guide member.

[0014] Furthermore, a centering frame is fixedly installed at the top of the left side baffle of the slope frame, and a motor is fixedly installed at the lower rear of the centering frame. A bidirectional screw is fixedly installed on the shaft of the motor. The bidirectional screw is located at the bottom of the centering frame. A slider is slidably connected to the front and rear ends of the bottom of the centering frame. A threaded hole is opened at the upper middle position of each slider. The front and rear ends of the bidirectional screw are respectively located in the threaded holes of a slider. An inclined rotating roller frame is fixedly installed on the right side of each slider. The two inclined rotating roller frames are symmetrically designed.

[0015] Compared with the prior art, the present invention has the following beneficial effects: 1. The flipping adjustment process does not rely on complex devices. It is achieved through the combined action of the arc-shaped inclined surfaces at both ends of the left side of the triangular limiter and the pressure blocks at the arc-shaped positions of guide plate A and guide plate B. This reduces manufacturing costs, minimizes equipment downtime caused by failure of complex components, and improves the stability of equipment operation.

[0016] 2. The spacing between the limiting rods on both sides of the top of conveyor belt B is adjustable, which can adapt to the stable conveying of bearing kits of different specifications; the positions of guide plate A and guide plate B can be adjusted by rotating adjusting bolt A and adjusting bolt B respectively to meet the guiding requirements of bearing kits of different specifications; rotating screw A can adjust the left and right position of the advancing frame, and rotating screw B can drive the triangular limiting component to slide up and down, so that the triangular limiting component can accurately match bearing kits of different sizes.

[0017] 3. During the conveyor belt B conveys the bearing assembly, the blower blows air onto the surface of the bearing assembly to remove light impurities such as dust. Then, the vacuum cleaner absorbs and removes the remaining impurities to ensure that the surface of the bearing assembly is clean and to avoid impurities from adversely affecting subsequent processing.

[0018] 4. The motor drives the bidirectional screw to rotate, causing the two sliders to move in opposite directions. This allows the two symmetrical inclined roller frames to center the bearing assembly and position it in the middle of conveyor belt A. This facilitates material handling in subsequent processes, ensures the uniformity of the bearing rings' position during processing, and improves processing accuracy.

[0019] 5. The design of the inclined rotating roller frame prevents damage to the surface of the bearing assembly due to contact interference when the bearing assembly comes into contact with the rotating roller of the inclined rotating roller frame, and also guides the bearing assembly to move in the center. Attached Figure Description

[0020] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings of the embodiments will be briefly described below.

[0021] In the attached diagram: Figure 1 A top view of the bearing ring end face uniform adjustment mechanism according to an embodiment of the present invention is shown. Figure 2 A side view of the bearing ring end face uniform adjustment mechanism according to an embodiment of the present invention is shown. Figure 3 A schematic side view of the overall structure of the base according to an embodiment of the present invention is shown; Figure 4 A schematic diagram of the overall main structure of the adjustment frame according to an embodiment of the present invention is shown; Figure 5 A top view of the overall structure of the adjustment frame according to an embodiment of the present invention is shown; Figure 6 A schematic side view of the overall structure of the adjustment frame according to an embodiment of the present invention is shown; Figure 7 A schematic top-side view of the overall structure of the adjustment frame according to an embodiment of the present invention is shown; Figure 8 A schematic side view of the overall structure of the centering frame according to an embodiment of the present invention is shown.

[0022] List of reference numerals 1. Base; 101. Pad; 102. Conveyor Belt A; 103. Conveyor Belt B; 104. Limiting Rod; 105. Fan; 106. Vacuum Cleaner; 107. Arc-shaped Guide Component; 2. Adjusting Frame; 201. Screw A; 202. Progressing Frame; 203. Screw B; 204. Triangular Limiting Component; 205. Slope Frame; 206. Guide Rail; 207. Triangular Guide Platform; 208. Side Plate; 209. Adjusting Bolt A; 210. Guide Plate A; 211. Adjusting Bolt B; 212. Guide Plate B; 3. Centering Frame; 301. Motor; 302. Bidirectional Screw; 303. Slider; 304. Angled Rotating Roller Frame; 4. Bearing Kit. Detailed Implementation

[0023] The technical solutions of the embodiments of this disclosure will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this disclosure, and not all embodiments. Based on the embodiments of this disclosure, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this disclosure.

[0024] Unless otherwise defined, all terms (including technical and scientific terms) used in the embodiments of this disclosure shall have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure pertains. It should also be understood that terms such as those defined in a common dictionary shall be interpreted as having a meaning consistent with their meaning in the context of the relevant art, and not as being interpreted in an idealized or highly formalized sense, unless expressly defined in the embodiments of this disclosure.

[0025] The terms "first," "second," and similar words used in the embodiments of this disclosure do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Similarly, the terms "a," "one," or "the" do not indicate a quantity limitation, but rather indicate the presence of at least one. Likewise, the terms "comprising" or "including" mean that the element or object preceding the word encompasses the elements or objects listed after the word and their equivalents, without excluding other elements or objects. In the following description, spatial and directional terms such as "upper," "lower," "front," "rear," "top," "bottom," "vertical," and "horizontal" may be used to describe embodiments of this disclosure; however, it should be understood that these terms are only for the convenience of describing the embodiments shown in the figures and do not require the actual device to be constructed or operated in a specific orientation. In the following description, the use of terms such as "connected," "joined," "fixed," and "attached" can refer to a direct connection between two elements or structures without other elements or structures, or to an indirect connection between two elements or structures via an intermediate element or structure, unless otherwise expressly stated herein.

[0026] Example: As attached Figure 1 To be continued Figure 8 As shown: This invention provides a bearing ring end face uniform adjustment mechanism, comprising: a base 1; a conveyor belt A102 is fixedly installed at the top front end of the base 1, an adjustment frame 2 is fixedly installed at the top right side of the conveyor belt A102, a threaded hole is opened at the right side of the adjustment frame 2, and a screw A201 is rotatably connected inside the threaded hole of the adjustment frame 2; a advancing frame 202 is slidably connected inside the adjustment frame 2, and the right middle position of the advancing frame 202 is rotatably connected to the left side of the screw A201; the top position of the advancing frame 202 is... A threaded hole is provided, and a screw B203 is rotatably connected inside the threaded hole of the advancing frame 202. A triangular limiting member 204 is slidably connected inside the advancing frame 202. The top position of the triangular limiting member 204 is rotatably connected to the bottom position of the screw B203. The left ends of the triangular limiting member 204 have an arc-shaped design. The lower left position of the adjusting frame 2 is fixedly connected to the lower right position of the slope frame 205. The slope frame 205 is located on the left side of the triangular limiting member 204. A baffle is provided on the left side of the slope frame 205.

[0027] A pad 101 is fixedly installed on the top right side of the base 1, a conveyor belt B103 is fixedly installed on the top of the pad 101, adjustable spacing limit bars 104 are provided on both sides of the top of the conveyor belt B103, and a bearing kit 4 is placed at the rear of the conveyor belt B103.

[0028] A fan 105 is fixedly installed at the top center of the conveyor belt B103, and a vacuum cleaner 106 is fixedly installed at the top front center of the conveyor belt B103. The vacuum cleaner 106 is located at the front end of the fan 105, and an arc-shaped guide 107 is provided at the front end of the conveyor belt B103. The arc-shaped guide 107 is located above the conveyor belt A102.

[0029] The upper left side of the slope frame 205 is located below and in front of the conveyor belt B103. The top of the slope frame 205 has a left-high and right-low structure design, and the internal slope of the slope frame 205 is equipped with a guide rail 206.

[0030] The right side of the guide rail 206 is fixedly connected to the left side of the triangular guide platform 207. The bottom of the triangular guide platform 207 is fixedly connected to the top right side of the slope frame 205. The triangular guide platform 207 is located below the triangular limiting member 204.

[0031] The slope frame 205 has a side plate 208 at the front and rear ends of its top, and each side plate 208 has a threaded hole on both sides of its middle. An adjusting bolt A209 is rotatably connected to the threaded hole of the front side plate 208. The inner side of the two adjusting bolts A209 is rotatably connected to the outer side of the guide plate A210. The guide plate A210 is located in the middle front of the two side plates 208. The bottom of the guide plate A210 corresponds to the front end of the top of the slope frame 205. The right side of the guide plate A210 is arc-shaped, and a pressure block is provided at the arc-shaped right side of the guide plate A210. The arc-shaped right side of the guide plate A210 corresponds to the arc-shaped front end of the triangular limiting member 204.

[0032] Among them, the side plate 208 at the rear end of the slope frame 205 is rotatably connected to the threaded hole of the adjustment bolt B211. The inner side of the two adjustment bolts B211 is rotatably connected to the outer side of the guide plate B212. The guide plate B212 is located in the middle rear position of the two side plates 208, and the guide plate B212 and the guide plate A210 are symmetrically designed. The bottom position of the guide plate B212 corresponds to the top rear end of the slope frame 205, and the right side of the guide plate B212 is arc-shaped. A pressure block is set at the right arc position of the guide plate B212. The right arc position of the guide plate B212 corresponds to the arc position at the rear end of the triangular limiter 204. The left side of the guide plate B212 bends backward, and the left bending position of the guide plate B212 is located at the right rear of the arc-shaped guide 107.

[0033] Among them, a centering frame 3 is fixedly installed at the top of the left side baffle of the slope frame 205. A motor 301 is fixedly installed at the lower rear of the centering frame 3. A bidirectional screw 302 is fixedly installed on the shaft of the motor 301. The bidirectional screw 302 is located at the bottom of the centering frame 3. A slider 303 is slidably connected to the front and rear ends of the bottom of the centering frame 3. A threaded hole is opened at the upper middle position of each slider 303. The front and rear ends of the bidirectional screw 302 are respectively located in the threaded hole of a slider 303. An inclined rotating roller frame 304 is fixedly installed on the right side of each slider 303. The two inclined rotating roller frames 304 are symmetrically designed.

[0034] When using: First, the bearing kit 4 to be processed is placed from the rear of the conveyor belt B103. According to the specifications of the bearing kit 4, the spacing of the limiting rods 104 on both sides of the top of the conveyor belt B103 is adjusted so that the bearing kit 4 can be stably conveyed on the conveyor belt B103.

[0035] During the conveyor belt B103 conveys the bearing assembly 4, the fan 105 at the top center is started to blow air onto the surface of the bearing assembly 4 to remove dust and other light impurities. Subsequently, the vacuum cleaner 106 located at the front end of the fan 105 works to absorb and remove the remaining impurities on the surface of the bearing assembly 4, completing the cleaning process.

[0036] The cleaned bearing kit 4 continues to be conveyed forward, guided by the arc-shaped guide 107 at the front end of the conveyor belt B103, and enters the position above the left side of the slope frame 205; After the bearing assembly 4 enters the slope frame 205, it slides down along the guide rail 206 inside, which is higher on the left and lower on the right. During the sliding process, the guide plates A210 and B212 on the side plates 208 at the front and rear ends of the top of the slope frame 205 guide it. The positions of the guide plates A210 and B212 can be adjusted by rotating the adjusting bolts A209 and B211 respectively to meet the guiding requirements of bearing assemblies 4 of different specifications. The bearing assembly 4 slides to the triangular guide platform 207 via the guide rail 206 and the cooperation of guide plates A210 and B212. Under the guidance of the triangular guide platform 207, it enters the arc-shaped positions at both ends of the triangular limiting member 204. The arc-shaped inclined surfaces at both ends of the left side of the triangular limiting member 204 work together with the pressure blocks at the arc-shaped positions of guide plates A210 and B212 to uniformly adjust and limit the end face of the bearing assembly 4, ensuring that the end face faces are aligned when it falls to the upper right position of the conveyor belt A102. The above-mentioned flipping adjustment is achieved without the aid of complex devices, which reduces costs and also reduces the failure rate.

[0037] Based on the specific dimensions of the bearing kit 4, rotate the screw A201 on the right side of the adjusting frame 2 to make the advancing frame 202 slide inside the adjusting frame 2 and adjust the left and right positions of the advancing frame 202; then rotate the screw B203 at the top of the advancing frame 202 to drive the triangular limiting member 204 to slide up and down inside the advancing frame 202, so that the triangular limiting member 204 can precisely match the bearing kit 4.

[0038] After adjustment, the bearing assembly 4 is conveyed to the conveyor belt A102 and transported to the left. At this time, the motor 301 is started to drive the bidirectional screw 302 to rotate. Since the front and rear ends of the bidirectional screw 302 are located in the threaded holes of the two sliders 303 respectively, and the two sliders 303 are slidably connected to the bottom of the centering frame 3, the rotation of the bidirectional screw 302 will drive the two sliders 303 to move in opposite directions, adjusting the distance between the two sliders 303. This allows the two symmetrical inclined roller frames 304 fixed on the outside of the sliders 303 to center the bearing assembly 4 to the middle position of the conveyor belt A102, facilitating material handling in subsequent processes. The design of the inclined roller frame 304 avoids interference and damage to the surface of the bearing assembly 4 when it comes into contact with the roller of the inclined roller frame 304, and can also guide the bearing assembly 4 to move in the center.

[0039] The above are merely specific embodiments of this disclosure, but the scope of protection of this disclosure is not limited thereto. The scope of protection of this disclosure shall be determined by the scope of the claims.

Claims

1. A bearing ring end face uniform adjustment mechanism, characterized in that, include: Base (1); a conveyor belt A (102) is fixedly installed at the top front end of the base (1), and an adjusting frame (2) is fixedly installed at the top right side of the conveyor belt A (102). A threaded hole is opened at the right side of the adjusting frame (2), and a screw A (201) is rotatably connected inside the threaded hole of the adjusting frame (2). A sliding advance frame (202) is slidably connected inside the adjusting frame (2). The middle right side of the advance frame (202) is rotatably connected to the left side of the screw A (201). A threaded hole is opened at the top of the advance frame (202), and the advance... The screw B (203) is rotatably connected in the threaded hole of the frame (202). The triangular limiter (204) is slidably connected in the inner position of the advancing frame (202). The top position of the triangular limiter (204) is rotatably connected to the bottom position of the screw B (203). The left ends of the triangular limiter (204) are arc-shaped. The lower left position of the adjusting frame (2) is fixedly connected to the lower right position of the slope frame (205). The slope frame (205) is located on the left side of the triangular limiter (204). A baffle is provided on the left side of the slope frame (205).

2. The bearing ring end face uniform adjustment mechanism as described in claim 1, characterized in that: A pad (101) is fixedly installed at the top middle right position of the base (1), a conveyor belt B (103) is fixedly installed at the top position of the pad (101), adjustable spacing limit rods (104) are provided at the top two sides of the conveyor belt B (103), and a bearing kit (4) is placed at the rear position of the conveyor belt B (103).

3. The bearing ring end face uniform adjustment mechanism as described in claim 2, characterized in that: A fan (105) is fixedly installed at the top middle position of the conveyor belt B (103), and a vacuum cleaner (106) is fixedly installed at the top front position of the conveyor belt B (103). The vacuum cleaner (106) is located at the front end of the fan (105). An arc-shaped guide (107) is provided at the front end of the conveyor belt B (103), and the arc-shaped guide (107) is located above the conveyor belt A (102).

4. The bearing ring end face uniform adjustment mechanism as described in claim 1, characterized in that: The upper left position of the slope frame (205) is located in front of and below the conveyor belt B (103). The top position of the slope frame (205) is designed with a left-high and right-low structure, and the internal slope position of the slope frame (205) is equipped with a guide rail (206).

5. The bearing ring end face uniform adjustment mechanism as described in claim 4, characterized in that: The right side of the guide rail (206) is fixedly connected to the left side of the triangular guide platform (207). The bottom of the triangular guide platform (207) is fixedly connected to the top right side of the slope frame (205). The triangular guide platform (207) is located below the triangular limiting member (204).

6. The bearing ring end face uniform adjustment mechanism as described in claim 1, characterized in that: The slope frame (205) has a side plate (208) at the front and rear ends of the top, and each side plate (208) has a threaded hole on both sides in the middle. An adjusting bolt A (209) is rotatably connected in the threaded hole of the front side plate (208). The inner side of the two adjusting bolts A (209) is rotatably connected to the outer side of the guide plate A (210). The guide plate A (210) is located in the middle front of the two side plates (208). The bottom of the guide plate A (210) corresponds to the front end of the top of the slope frame (205). The right side of the guide plate A (210) is arc-shaped. A pressure block is provided at the arc-shaped right side of the guide plate A (210). The arc-shaped right side of the guide plate A (210) corresponds to the arc-shaped front end of the triangular limiting piece (204).

7. The bearing ring end face uniform adjustment mechanism as described in claim 6, characterized in that: Adjusting bolts B (211) are rotatably connected in the threaded holes of the side plate (208) at the rear end of the slope frame (205). The inner positions of the two adjusting bolts B (211) are rotatably connected to the outer positions of the guide plate B (212). The guide plate B (212) is located in the middle rear position of the two side plates (208). The guide plate B (212) and the guide plate A (210) are symmetrically designed. The bottom position of the guide plate B (212) corresponds to the top rear end of the slope frame (205). The right side position of the guide plate B (212) is arc-shaped. A pressure block is provided at the right arc position of the guide plate B (212). The right arc position of the guide plate B (212) corresponds to the rear arc position of the triangular limiter (204). The left side position of the guide plate B (212) bends backward. The left bending position of the guide plate B (212) is located at the right rear position of the arc guide (107).

8. The bearing ring end face uniform adjustment mechanism as described in claim 1, characterized in that: A centering frame (3) is fixedly installed at the top of the left side baffle of the slope frame (205). A motor (301) is fixedly installed at the lower rear of the centering frame (3). A bidirectional screw (302) is fixedly installed on the shaft of the motor (301). The bidirectional screw (302) is located at the bottom of the centering frame (3). A slider (303) is slidably connected to the front and rear ends of the bottom of the centering frame (3). A threaded hole is opened at the upper middle position of each slider (303). The front and rear ends of the bidirectional screw (302) are respectively located in the threaded hole of a slider (303). An inclined rotating roller frame (304) is fixedly installed on the right side of each slider (303). The two inclined rotating roller frames (304) are symmetrically designed.

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