A composite precision transmission device

Abstract

The present invention relates to the field of precision transmission components and discloses a composite precision transmission device, including a linear transmission component, which is rotatably arranged in a rotating transmission component. The rotating transmission component includes an outer ring sleeved outside the linear transmission component, a rolling support ring arranged between the outer ring and the linear transmission component, and a first rolling body arranged on the rolling support ring. A first limiting mechanism for limiting the axial movement of the rolling support ring relative to the linear transmission component is provided on the linear transmission component. The first limiting mechanism includes two closed retaining rings fixedly sleeved on the outer wall of the linear transmission component, the closed retaining rings are fitted with both ends of the rolling support ring, and a second limiting mechanism for limiting the axial sliding of the closed retaining ring relative to the rolling support ring is provided on the outer ring. The device can realize linear motion and rotational motion, has a small size, high precision and a long service life.

Description

Technical Field

[0001] The present invention relates to the field of precision transmission components, and in particular to a composite precision transmission device. Background Art

[0002] As precision transmission devices, bearings are widely used in precision equipment or special machinery industries including electronic equipment, food machinery, packaging machinery, medical machinery, printing machinery, textile machinery, machinery, instruments, robots, tool machinery, CNC machine tools, automobiles and digital three-dimensional coordinate measuring equipment.

[0003] The transmission of the bearing is divided into linear transmission and rotational transmission. The structure of the linear transmission can refer to the quick-release linear bearing disclosed in the Chinese patent announcement CN213575178U, which includes an outer ring sleeve and a retaining frame. There are several raceways distributed circumferentially on the retaining frame. Each raceway is "J"-shaped when viewed from the inner ring of the retaining frame and "runway"-shaped when viewed from the outer ring. Each raceway is filled with rolling elements, and the two ends of the retaining frame and the outer ring sleeve are assembled through a clamping structure.

[0004] The structure of the rotary transmission can refer to a ball bearing disclosed in the Chinese patent publication number CN210034164U, which includes an outer ring, an inner ring, rolling elements and a retaining frame. The rolling elements are arranged on the retaining frame, and the retaining frame is located between the outer ring and the inner ring. A clamping structure is provided on both sides of the retaining frame to enable the outer ring, inner ring and retaining frame to be assembled.

[0005] Conventional linear bearings can only meet the needs of linear motion. The force of their load is vertically downward. Under the action of power, the rolling element floats tightly on the outer wall of the shaft it cooperates with, and performs vertical or horizontal linear reciprocating motion with the mechanical transmission device. However, rotary bearings perform positive and negative rotational motion. Some devices that require both linear motion and rotational motion require the combination of linear transmission components and rotary bearings. Using the two types of bearings simultaneously will increase the complexity of the assembly structure and reduce the accuracy. Summary of the Invention

[0006] The present invention addresses the shortcomings of existing equipment that realizes linear and reciprocating motion, which requires the simultaneous installation of linear bearings and rotary bearings, resulting in increased structural complexity, increased volume and decreased precision. It provides a composite precision transmission device that can realize switching between rotary motion and linear motion.

[0007] In order to solve the above technical problems, the present invention is solved by the following technical solutions:

[0008] A composite precision transmission device includes a linear transmission component, which is rotatably arranged in a rotating transmission component. The rotating transmission component includes an outer ring mounted on the outside of the linear transmission component, a rolling support ring arranged between the outer ring and the linear transmission component, and a first rolling body arranged on the rolling support ring. A first limiting mechanism for limiting the axial movement of the rolling support ring relative to the linear transmission component is provided on the linear transmission component. The first limiting mechanism includes two closed retaining rings fixedly mounted on the outer wall of the linear transmission component, the closed retaining rings are in contact with the two ends of the rolling support ring, and a second limiting mechanism for limiting the axial sliding of the closed retaining ring relative to the outer ring is provided on the outer ring.

[0009] By adopting the above scheme, the linear transmission component is subjected to an axial force, and the rotating bearing is subjected to a radial force. When the two are compounded, the volume and force of the compounded component need to be considered. The linear transmission component is assembled as the "inner ring" of the rotating bearing and the rolling support ring through the first limiting mechanism, so that the linear transmission component can rotate circumferentially relative to the outer ring, and the first limiting mechanism is configured as a closed retaining ring. When the support ring rotates relative to the outer ring, the closed retaining ring can evenly bear the axial force generated by the rolling support ring, so that the rotation of the linear transmission component is more stable and smoother, avoiding axial movement, thereby significantly extending the service life. The second limiting mechanism is used to limit the axial movement of the closed retaining ring, so that the outer ring, the rolling support ring and the linear transmission component are combined into a whole. Therefore, the composite precision transmission device can realize linear motion and rotational motion, and the volume is greatly reduced relative to the directly compounded structure. It can also eliminate the problems of reduced fitting accuracy and reduced service life when two bearings are installed separately.

[0010] Preferably, the closed retaining ring is an eccentric retaining ring, which includes a second closed ring mounted on the linear transmission component and an eccentric retaining portion protruding from the local arc surface of the inner ring wall of the second closed ring, and a first annular retaining groove is recessed on the outer wall of the linear transmission component for the eccentric retaining portion to be inserted into.

[0011] By adopting the above scheme, the closed retaining ring is set as an eccentric retaining ring. Through the eccentric retaining portion of its local arc surface, the second closed ring can be moved to the first annular retaining groove under the application of a certain external force. After the eccentric retaining portion is clamped into the first annular retaining groove, the eccentric retaining ring can be fixed on the outer wall of the linear transmission component, thereby playing the role of limiting the axial movement of the rolling support ring.

[0012] Preferably, the arc of the eccentric clamping portion distributed on the eccentric clamping ring is less than or equal to 180°.

[0013] With the above solution, only when the arc angle of the eccentric clamping portion is less than or equal to 180° can the second closed loop be sleeved outside the linear transmission component and moved to the first annular clamping groove for clamping under the action of external force.

[0014] Preferably, the thickness of the eccentric clamping portion is smaller than the thickness of the second closed loop.

[0015] By adopting the above scheme, the thickness of the eccentric clamping part is smaller than the thickness of the second closed ring. On the one hand, it is convenient to introduce the second closed ring into the linear transmission component. On the other hand, when the eccentric clamping part is inserted into the first annular clamping groove, the eccentric clamping part area is not set to abut against the outer wall of the linear transmission component, thereby increasing the radial bearing capacity of the second closed ring.

[0016] Preferably, the eccentric clamping portion includes a plurality of clamping points circumferentially spaced around the inner ring wall of the second closed ring, and the clamping points are in the shape of an outwardly convex arc.

[0017] By adopting the above scheme, the eccentric snap ring is fixed on the linear transmission component by using multiple clamping points and the first annular clamping groove. The multi-point clamping increases the firmness of the clamping. The clamping points are in an outward convex arc shape to facilitate the introduction of the eccentric snap ring onto the linear transmission component.

[0018] Preferably, the eccentric clamping portion includes an arc-shaped protrusion protruding from the inner ring wall of the second closed ring, and the arc-shaped protrusion is in a "crescent" shape with the concave surface facing the inner wall of the second closed ring.

[0019] By adopting the above scheme, the eccentric clamping part is set as an arc-shaped protrusion. The setting of the relative clamping point can significantly increase the area of ​​clamping with the first annular clamping groove, and increase the firmness of the clamping of the eccentric clamping ring on the linear transmission component. The arc-shaped protrusion is set into a "crescent" shape, and the arc-shaped transition between its two sides and the inner wall of the second closed ring is the key to ensuring that the entire eccentric clamping ring can be mounted on the outside of the linear transmission component under a certain external force and moved to the first annular clamping groove for clamping.

[0020] Preferably, the second limiting mechanism includes a second annular groove recessed in the inner ring wall of the outer ring and a retaining spring partially engaged therein, and the retaining spring fits snugly with the closed retaining ring.

[0021] With the above solution, the retaining ring is easy to install. After the retaining ring is partially clamped in the second annular groove, the retaining ring is partially exposed outside the outer ring to block the closing retaining ring.

[0022] Preferably, an auxiliary rolling mechanism for increasing the radial load performance of the linear transmission component is provided between the retaining spring and the closed retaining ring.

[0023] By adopting the above scheme, the auxiliary rolling mechanism can, on the one hand, share the radial pressure on the linear transmission components, improve the smoothness of rotation of the linear transmission components relative to the outer ring and the radial force bearing capacity, and can also convert the sliding friction between the retaining spring and the closed retaining ring into rolling friction, reduce wear, and improve the smoothness of rotation of the linear transmission components, thereby significantly improving the overall service life.

[0024] Preferably, the auxiliary rolling mechanism includes a second rolling body distributed around the circumference of the linear transmission component, and a first closed ring with a smooth surface is arranged between the retaining spring and the second rolling body. The second rolling body is simultaneously fitted with the inner wall of the outer ring, the outer wall of the linear transmission component, the first closed ring and the closed retaining ring.

[0025] By adopting the above solution, the second rolling body is used to bear part of the radial pressure, and the first closed ring is set up, which can improve the smoothness of the rolling of the second rolling body. At the same time, it ensures that the second rolling body rolls along the predetermined track, avoids its axial deviation, and avoids its rolling from getting stuck or stuck.

[0026] Preferably, the first rolling elements are clearance-fitted with each other and are circumferentially staggered and distributed on the rolling support ring.

[0027] With the above solution, the first rolling elements are independently arranged without interfering with each other, and no collision occurs between the first rolling elements. The linear transmission component rotates more smoothly and stably relative to the outer ring.

[0028] Preferably, the first rolling elements are distributed in at least N rows at intervals along the axial direction of the rolling bearing ring, where N≥3.

[0029] Using the above scheme, the rolling support ring is centrally arranged between the outer ring and the linear transmission component, and the first rolling bodies are arranged in three or more single-digit arrays at axial intervals along the linear transmission component. The purpose of the arrangement is that there must be a group of first rolling bodies near the center of the linear transmission component that can bear the radial pressure exerted on the linear transmission component when it rotates relative to the outer ring, and the purpose of the circumferential staggered distribution of the first rolling bodies is to further improve the uniformity of the radial force of the linear transmission component and improve the smoothness and stability of its rotation relative to the outer ring.

[0030] Preferably, a flange is fixed to one end of the outer ring, the flange is threadedly connected to the outer ring, and an electric welding wire for welding the flange and the outer ring is embedded in the inner wall of the flange.

[0031] By adopting the above scheme, a flange is provided to facilitate the fixation of the outer ring on the equipment, thereby realizing the installation of the entire transmission device. The flange is first pre-fixed by threaded connection, and then the electric welding wire is melted by heating to firmly weld the flange and the outer ring.

[0032] The present invention has significant technical effects due to the adoption of the above technical solutions:

[0033] 1. The linear transmission component is assembled as the "inner ring" of the rotating bearing and the rolling support ring through the first limiting mechanism, so that the linear transmission component can rotate circumferentially relative to the outer ring, and the first limiting mechanism is configured as a closed retaining ring. When the support ring rotates relative to the outer ring, the closed retaining ring can evenly bear the axial force generated by the rolling support ring, so that the linear transmission component rotates more stably and smoothly, avoiding axial movement, thereby significantly extending the service life. The second limiting mechanism is used to limit the axial movement of the closed retaining ring, so that the outer ring, the rolling support ring and the linear transmission component are combined into a whole. Therefore, the composite precision transmission device can realize linear motion and rotational motion, and the volume is greatly reduced relative to the direct composite structure. It can also eliminate the problems of reduced fitting accuracy and reduced service life that exist in the separate installation of two bearings.

[0034] 2. The closed retaining ring is configured as an eccentric snap ring, which includes a second closed ring and an eccentric snap portion protruding from an area within 180° of the second closed ring. Through the eccentric snap portion, the second closed ring can be moved to the first annular snap groove under the application of a certain external force to achieve snap-fit ​​fixation, thereby playing a role in limiting the axial movement of the rolling support ring; the thickness of the eccentric snap portion is less than that of the second closed ring. On the one hand, it is convenient for the second closed ring to be introduced into the linear transmission component. On the other hand, when the eccentric snap portion is inserted into the first annular snap groove, the area where the eccentric snap portion is not provided abuts against the outer wall of the linear transmission component, thereby increasing the radial bearing capacity of the second closed ring.

[0035] 3. Add an auxiliary rolling mechanism. On the one hand, the auxiliary rolling mechanism can share the radial pressure on the linear transmission components, improve the smoothness of the rotation of the linear transmission components relative to the outer ring and the radial load capacity, and can also convert the sliding friction between the retaining spring and the closed retaining ring into rolling friction, reduce wear, and improve the smoothness of the rotation of the linear transmission components, thereby significantly improving the overall service life. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 This is an axonometric view of a composite precision transmission device of Example 1;

[0037] Figure 2 This is a disassembled diagram of a composite precision transmission device of Example 1;

[0038] Figure 3 is a front view of the linear transmission component of Example 1;

[0039] Figure 4 yes Figure 3 AA cross-sectional view;

[0040] Figure 5 is an axonometric view of the rolling bearing ring of Example 1;

[0041] Figure 6This is a front view of the closed retaining ring of Example 1;

[0042] Figure 7 yes Figure 6 Cross-sectional view of BB;

[0043] Figure 8 This is a rear view of the outer ring and flange ring of Example 1 after assembly;

[0044] Figure 9 yes Figure 8 Cross-sectional view of CC;

[0045] Figure 10 This is a front view of a composite precision transmission device according to Example 1;

[0046] Figure 11 yes Figure 10 Cross-sectional view of DD;

[0047] Figure 12 This is an axonometric view of the closed retaining ring of Example 2.

[0048] The names of the parts indicated by the numerical labels in the above drawings are as follows: 1. Flange; 101. Wire groove; 102. Mounting hole; 2. Retaining spring; 3. First closed loop; 4. Linear transmission component; 401. First annular retaining groove; 5. Second rolling element; 6. Rolling support ring; 601. Through hole; 7. First rolling element; 8. Second closed loop; 801. Arc-shaped protrusion; 9. Outer ring; 901. Second annular retaining groove; 10. Retaining point. DETAILED DESCRIPTION

[0049] The present invention is further described in detail below with reference to the accompanying drawings and embodiments.

[0050] Example 1

[0051] A composite precision transmission device, referring to Figures 1-11As shown, it includes a linear transmission component 4. The linear transmission component 4 of this embodiment is a linear bearing. The linear transmission component 4 is rotatably arranged in a rotating transmission component. The rotating transmission component includes an outer ring 9 sleeved on the outside of the linear transmission component 4, a rolling support ring 6 arranged between the outer ring 9 and the linear transmission component 4, and a first rolling body 7 arranged on the rolling support ring 6. The outer ring 9 is made of GCr15, and the rolling support ring 6 is made of aluminum alloy. A first limiting mechanism is provided on the linear transmission component 4 to limit the axial movement of the rolling support ring 6 relative to the linear transmission component 4 while ensuring the stable rotation of the rolling support ring 6 and the outer ring 9 relative to the linear transmission component 4. The first limiting mechanism includes two closed retaining rings fixedly sleeved on the outer wall of the linear transmission component 4, and the closed retaining ring is fitted with both ends of the rolling support ring 6. Due to its closed structure, the closed retaining ring can avoid axial movement of the rolling support ring 6 relative to the linear transmission component 4 when rotating, ensuring that the linear transmission component 4 is evenly stressed. This design can improve the accuracy of the overall operation and increase the service life of the finishing.

[0052] Since the closing retaining ring is installed after the rolling support ring 6 is installed, the assembly of the closing retaining ring is a design difficulty. In this embodiment, the closing retaining ring is an eccentric retaining ring. The eccentric retaining ring is made of GCr15 and has a hardness of HRC55-60 after heat treatment. Figure 6-Figure 7 As shown, the eccentric clamping ring includes a second closed ring 8 sleeved on the linear transmission component 4, the inner and outer ring walls of the second closed ring 8 are concentrically arranged, an eccentric clamping portion is provided on the local arc surface of the inner ring wall of the second closed ring 8, and a first annular clamping groove 401 for the eccentric clamping portion to be clamped is recessed on the outer ring wall of the linear transmission component 4. The arc of the eccentric clamping portion distributed on the second closed ring 8 needs to be less than or equal to 180° in order to satisfy the second closed ring 8 being able to be sleeved on the linear transmission component 4 and clamped into the first annular clamping groove 401 at the same time. The eccentric clamping portion is included in the second closed ring 8. The arc-shaped protrusion 801 is convexly provided on the ring wall, and the arc-shaped protrusion 801 is in a "crescent" shape with the concave side facing the inner wall of the second closed ring 8. The "crescent" shape design allows the two sides of the arc-shaped protrusion 801 to have a smooth transition with the inner wall of the second closed ring 8, and the eccentric retaining ring can be introduced into the linear transmission component 4. In order to further increase the firmness of the connection between the eccentric retaining ring and the linear transmission component 4, the thickness of the eccentric retaining part is smaller than the thickness of the second closed ring 8. After such a setting, the area without the eccentric retaining part abuts against the outer wall of the linear transmission component 4, which can increase the radial bearing capacity of the second closed ring 8.

[0053] The rolling support ring is set in the center, combined with Figure 2 and Figure 5As shown, a through hole 601 is provided on the rolling support ring 6 for the first rolling body 7 to roll therein, and each through hole 601 is independently provided to ensure that the first rolling bodies 7 do not contact each other and avoid collision between the first rolling bodies 7. The first rolling bodies 7 are clearance-fitted with each other and are circumferentially staggered on the rolling support ring 6. The first rolling bodies 7 are distributed in at least N (N≥3) rows along the axial direction of the rolling support ring 6, and the central row of first rolling bodies 7 is located on the central cross-section of the linear transmission component 4 and the outer ring 9. In this embodiment, three rows of first rolling bodies 7 are provided, and each row has eight first rolling bodies 7. The purpose of the above design is that there must be a group of first rolling bodies 7 near the center of the linear transmission component 4 that can bear the radial pressure exerted on the linear transmission component 4 when it rotates relative to the outer ring 9. After the first rolling bodies 7 are circumferentially staggered, the uniformity of the radial force on the linear transmission component 4 can be further improved, and the smoothness and stability of its rotation relative to the outer ring 9 can be improved.

[0054] After the support bearing and the rolling support ring 6 are assembled, it is necessary to limit the axial movement of the semi-composite relative to the outer ring 9. Therefore, a second limiting mechanism is provided on the outer ring 9 to limit the axial movement of the semi-composite. Figure 1-Figure 2 As shown, the second limiting mechanism includes a second annular groove recessed on the side of the inner ring wall of the outer ring 9 opposite to the closed retaining ring and a retaining spring 2 partially engaged therein.

[0055] The clamping spring 2 is directly fitted with the eccentric clamping ring. When the linear transmission component 4 rotates relative to the outer ring 9, the sliding friction between the two will cause the linear transmission component 4 to rotate poorly. Therefore, an auxiliary rolling mechanism is provided between the clamping spring 2 and the eccentric clamping ring. Figure 2 and Figure 11 As shown, the auxiliary rolling mechanism includes a second rolling body 5 distributed around the circumference of the linear transmission component 4, and a first closed ring 3 with a smooth surface is arranged between the retaining spring 2 and the second rolling body 5. The second rolling body 5 is simultaneously fitted with the inner wall of the outer ring 9, the outer wall of the linear transmission component 4, the first closed ring 3 and the closed retaining ring. On the one hand, the auxiliary rolling mechanism can share the radial pressure exerted on the linear transmission component 4, improve the smoothness of rotation of the linear transmission component 4 relative to the outer ring 9 and the radial force bearing capacity, and can also convert the sliding friction between the retaining spring 2 and the closed retaining ring into rolling friction, reduce wear, and improve the smoothness of rotation of the linear transmission component 4, thereby significantly improving the overall service life. The setting of the first closed ring 3 is far away from the eccentric retaining ring, which is used to ensure that the second rolling body 5 does not move axially to ensure the smoothness of rotation of the linear transmission component 4.

[0056] In order to facilitate the installation of the outer ring 9 on the equipment, a flange 1 is fixed at one end of the outer ring 9. Figure 8-Figure 9As shown, the flange 1 is provided with mounting holes 102 around it for the bolts to pass through, the outer wall of the outer ring 9 is provided with an external thread, the flange 1 has an internal threaded through hole matching the external thread, and an annular welding wire groove 101 is also provided in the internal threaded hole of the flange 1, and electric welding wire is arranged in the welding wire groove 101. When the flange 1 is threadedly connected to the outer ring 9, the electric welding wire is melted by heating to achieve welding of the flange 1 and the outer ring 9.

[0057] Assembly steps:

[0058] 1. Assembly of flange 1 and outer ring 9: Thread flange 1 and outer ring 9 together and then heat and weld them tightly;

[0059] 2. Assemble the rolling support ring 6 and the linear transmission component 4: First, place the first rolling element 7 on the rolling support ring 6, insert the rolling support ring 6 into the linear transmission component 4, and then eccentrically insert the eccentric retaining rings on both sides into the first annular retaining groove 401 to achieve axial positioning of the rolling support ring 6 and the linear transmission component 4;

[0060] 3. Assemble the linear transmission component 4 and the outer ring 9: First, insert the linear transmission component 4 into the outer ring 9, then place the second rolling elements 5 on both sides, then place the first closed rings 3 on both sides, and finally clamp the retaining springs 2 on both sides.

[0061] Example 2

[0062] The difference between this embodiment and embodiment 1 is that, referring to Figure 12 As shown, the eccentric clamping portion has different configurations. The eccentric clamping portion of this embodiment includes a plurality of clamping points 10 circumferentially spaced around the inner ring wall of the second closed loop 8 , and the clamping points 10 are in the shape of an outwardly convex arc.

Claims

1. A composite precision transmission device, comprising a linear transmission component (4), characterized in that: The linear transmission component (4) is rotatably arranged in a rotating transmission component, and the rotating transmission component includes an outer ring (9) sleeved outside the linear transmission component (4), a rolling support ring (6) arranged between the outer ring (9) and the linear transmission component (4), and a first rolling body (7) arranged on the rolling support ring (6). A first limiting mechanism for limiting the axial movement of the rolling support ring (6) relative to the linear transmission component (4) is provided, and the first limiting mechanism includes two closed retaining rings fixedly sleeved on the outer wall of the linear transmission component (4), and the closed retaining rings and the rolling support ring (6) are in contact with each other. The two ends of the linear transmission component (4) are fitted together, the closed retaining ring is an eccentric retaining ring, the eccentric retaining ring comprises a second closed ring (8) sleeved on the linear transmission component (4) and an eccentric clamping portion convexly provided on a local arc surface of the inner ring wall of the second closed ring (8), a first annular clamping groove (401) is recessed on the outer wall of the linear transmission component (4) for the eccentric clamping portion to be clamped, the arc of the eccentric clamping portion distributed on the eccentric retaining ring is less than or equal to 180°, the thickness of the eccentric clamping portion is less than the thickness of the second closed ring (8), and a second limiting mechanism for limiting the axial sliding of the closed retaining ring relative to the outer ring (9) is provided.

2. A composite precision transmission device according to claim 1, characterized in that: The eccentric clamping portion comprises a plurality of clamping points (10) circumferentially spaced and distributed around the inner ring wall of the second closed ring (8), wherein the clamping points are in an outwardly convex arc shape.

3. The composite precision transmission device according to claim 1, characterized in that: The eccentric clamping portion includes an arc-shaped protrusion (801) protruding from the inner ring wall of the second closed ring (8), and the arc-shaped protrusion (801) is in a "crescent" shape with the concave surface facing the inner wall of the second closed ring (8).

4. A composite precision transmission device according to claim 1, characterized in that: The second limiting mechanism comprises a second annular groove (901) recessed in the inner ring wall of the outer ring (9) and a retaining spring (2) partially engaged therein, wherein the retaining spring (2) is in close contact with the closed retaining ring.

5. A composite precision transmission device according to claim 4, characterized in that: An auxiliary rolling mechanism for increasing the radial load performance of the linear transmission component (4) is provided between the clamping spring (2) and the closed retaining ring.

6. A composite precision transmission device according to claim 5, characterized in that: The auxiliary rolling mechanism comprises a second rolling body (5) distributed around the circumference of the linear transmission component (4), a first closed ring (3) is provided between the retaining spring (2) and the second rolling body (5), and the second rolling body (5) is simultaneously fitted with the inner wall of the outer ring (9), the outer wall of the linear transmission component (4), the first closed ring (3) and the closed retaining ring.

7. The composite precision transmission device according to claim 1, characterized in that: The first rolling bodies (7) are clearance-matched with each other and are circumferentially staggered and distributed on the rolling support ring (6).

8. The composite precision transmission device according to claim 7, characterized in that: The first rolling bodies (7) are distributed in at least N rows at intervals along the axial direction of the rolling support ring (6), where N≥3.

9. The composite precision transmission device according to claim 1, characterized in that: A flange (1) is fixed to one end of the outer ring (9), and the flange (1) is threadedly connected to the outer ring (9). An electric welding wire for welding the flange (1) and the outer ring (9) is embedded in the inner wall of the flange (1).

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