Crossed roller bearing and method for manufacturing the same

Abstract

The application relates to the technical field of bearings, and particularly discloses a cross-roller bearing and a manufacturing method thereof, which comprises the following steps: S10, pre-processing a bearing ring and a plug; S20, pre-assembly; S30, rough processing; S40, heat treatment; S50, fine processing; S60, assembly; and S70, welding. The cross-roller bearing and the manufacturing method thereof change the structural form of fixing the plug through a conical pin in the prior art through the special design of the plug and the filling hole, can effectively prevent the plug from moving in any direction in the filling hole, avoid the repeated positioning accuracy of the plug after being disassembled and assembled back to the original position, and greatly improve the qualified rate of one-time assembly of the bearing. A structural mistake-proof mechanism is constructed, the problem of reverse assembly of the plug in the assembly process can be effectively prevented, the assembly efficiency and the assembly accuracy are improved, the structural stability after assembly is obviously improved, and the problems of bearing jamming or abnormal sound caused by displacement of the plug due to vibration or running impact can be effectively prevented.

Description

Technical Field

[0001] This invention relates to the field of bearing technology, and specifically to a crossed roller bearing and its manufacturing method. Background Technology

[0002] Crossed roller bearings are widely used in high-precision robots, CNC machine tools, and other fields because they can simultaneously withstand radial, axial, and overturning moments. Traditional crossed roller bearings typically have pre-drilled roller filling holes on the inner or outer ring, with pre-installed plugs that fit the filling holes. The plugs have radially extending tapered holes, and pin holes corresponding to the tapered holes are provided on the end face of the inner or outer ring. For example, the slewing roller bearing disclosed in Chinese utility model patent CN2607464Y, during assembly, rollers are filled through the filling holes. After filling, the plugs are placed into the filling holes, and tapered pins are inserted from the end face of the bearing into the pin holes and tapered holes to position and fix the plugs.

[0003] The aforementioned traditional crossed roller bearing structure and assembly method have the following technical defects:

[0004] (1) The assembly process is complicated: During the assembly process, the plug and the tapered pin need to be assembled first. After the assembly is completed, the tapered pin and the plug are machined. After the machining is completed, the tapered pin and the plug are removed and the rollers are filled. After the filling is completed, the plug and the tapered pin are reinstalled. Since the tapered pin and the plug need to be machined at the same time, there are many machined surfaces. During the assembly process, the repeated disassembly and assembly can easily cause damage to the mating surfaces and reduce the accuracy.

[0005] (2) Poor precision consistency: The plug and the inner and outer rings are machined separately. Due to the influence of manufacturing tolerances, there are often gaps in the groove after assembly. The roller will generate vibration and uneven load during operation.

[0006] (3) Low yield: The assembly dimensions are limited by the superposition error of multiple parts dimensions (such as plugs, tapered pins, pin holes, tapered holes), resulting in poor robustness, easy assembly interference or loosening, and difficulty in quality control.

[0007] (4) Heat treatment has a significant impact: the inner and outer rings of the bearing or the pin hole and tapered hole may deform after heat treatment, making it difficult to assemble the plug or the fit clearance may not reach the preset accuracy, further reducing the product qualification rate.

[0008] Furthermore, Chinese invention patent CN104295598A discloses a slewing bearing with a through hole and a plug. In this patented design, one of the rings, serving as the inner or outer ring of the bearing, has a through hole for inserting rollers for assembly and maintenance, and a plug for sealing the through hole. The through hole is a stepped hole, and the plug is a stepped shaft-like structure adapted to the stepped hole. Although this patented design differs from traditional crossed roller bearings in the structure of the plug and lacks one tapered pin, resulting in fewer parts and fewer machined surfaces, thus improving cumulative assembly errors, this design still suffers from the following technical defects:

[0009] (1) The clearance fit between the through hole and the plug facilitates manual insertion, but it also makes it difficult for the plug to be stably positioned before the assembly is completed. Before the raceway is fully closed or before it is fixed in time with pins / screws, the plug is very easy to loosen or fall off during handling, flipping or slight vibration, which poses a potential interference to subsequent assembly processes and affects assembly efficiency and safety.

[0010] (2) The large and small diameter sections of the through hole are concentric. Correspondingly, the large and small diameter sections of the plug are coaxial. There is no anti-rotation design in the circumferential direction. After assembly, the plug may rotate under vibration or force during operation, which may lead to misalignment or interference with the raceway contact surface.

[0011] (3) The connection between the plug and the through hole is not provided with a tapered guide section, which makes the centering poor during the assembly process. Especially under small clearance fit, the lack of guide tapering makes it easy to "get stuck" or "repeated trial assembly". The assembly efficiency and consistency are poor, which increases the assembly difficulty, requires a high level of operator proficiency, and is not conducive to subsequent automated assembly.

[0012] (4) The large and small diameter sections of the through hole are concentric, and the large and small diameter sections of the plug are coaxial, presenting a completely symmetrical design. This lacks an assembly error prevention mechanism and poses a risk of incorrect assembly. After the raceway is machined, even if the plug is installed 180° backwards, it cannot be identified by appearance or assembly resistance, making it very easy to make the mistake of "reverse assembly". Once the plug is installed backwards, the raceway surface will have stepped misalignment, which will seriously affect the smoothness of the roller operation and the overall service life. Summary of the Invention

[0013] The technical problem to be solved by the present invention is to provide an improved crossed roller bearing and its manufacturing method, so as to solve the technical defects in the structure and assembly method of the crossed roller bearing in the prior art.

[0014] To solve the above-mentioned technical problems, the present invention provides the following technical solution: a method for manufacturing a crossed roller bearing, comprising the following steps:

[0015] S10: Pre-process the bearing ring and plug, wherein the bearing ring and plug are made of the same material;

[0016] The plug includes a cylindrical section and a lug structure located at one end of the cylindrical section. A first positioning step is formed between the cylindrical section and the lug structure. The projection of the lug structure in the axial direction of the cylindrical section is based on the asymmetric design of the axis of the cylindrical section.

[0017] The bearing ring is provided with a filling hole adapted to the plug. The filling hole includes a round hole adapted to the columnar section and a slot adapted to the lug structure. A second positioning step adapted to the first positioning step is formed between the slot and the round hole.

[0018] The lug structure and the slot are fitted with a small taper.

[0019] S20: Pre-assembly, pressing the plug into the filling hole, and upsetting the outer end face of the lug structure on the plug so that the lug structure and the slot are in a slight interference fit;

[0020] S30: Rough machining, which involves rough machining the inner and outer ring surfaces of the assembly formed in S20 by turning.

[0021] S40: Heat treatment, the assembly obtained in S30 is heat-treated to harden it and obtain the required hardness;

[0022] S50: Finishing, finishing the inner and outer ring surfaces of the assembly obtained in S40 to the required precision;

[0023] S60: Assembly, including at least the following steps:

[0024] S61: Remove the plug from the assembly obtained from the finishing process in S50;

[0025] S62: Insert the rollers and spacers into the groove between the inner and outer rings of the bearing through the filling hole;

[0026] S63, After the rollers and spacers are installed, the plug is installed into the filling hole;

[0027] S70: Weld the plug to the bearing ring for fixation.

[0028] In a preferred embodiment, the interference fit between the lug structure and the slot is 5μm–50μm.

[0029] In a preferred embodiment, the taper angle between the lug structure and the slot is 0.5°–7°.

[0030] In a preferred embodiment, the bearing ring of the filling hole is configured as either the inner ring or the outer ring of the bearing.

[0031] In a preferred embodiment, the lug structure has at least one plane in the circumferential direction.

[0032] In a preferred embodiment, in S70, the welding is performed using a laser welding process.

[0033] The present invention also discloses a crossed roller bearing, which is manufactured by the aforementioned manufacturing method.

[0034] The crossed roller bearing and its manufacturing method of the present invention have the following advantages compared with the prior art:

[0035] (1) The first step and the second step achieve precise positioning of the filling hole in the axial direction, which can effectively prevent the plug from moving in the axial direction of the filling hole, and also provide stable support for the subsequent welding process of the plug.

[0036] (2) The projection of the lug structure on the axial direction of the columnar section is based on the structural form of the asymmetric design of the axial direction of the columnar section, which constructs a structural error prevention mechanism, so that the plug can only be installed into the filling hole in the only correct posture, avoiding assembly errors from the source, ensuring the repeatability of the positioning accuracy of the plug after it is removed and reassembled, and greatly improving the pass rate of the cross roller bearing in one assembly.

[0037] (3) The projection of the lug structure on the axial direction of the columnar section is based on the asymmetrical design of the columnar section axis, which realizes the circumferential locking fit between the plug and the filling hole, eliminates the risk of plug rotation, significantly improves the structural stability after assembly, and effectively prevents the problem of bearing jamming or abnormal noise caused by the displacement of the plug due to vibration or running impact.

[0038] (4) The lug structure of the plug and the slot of the filling hole are slightly interference fit, which ensures reliable fixation without affecting the operability during the assembly process, and also facilitates the simulation assembly and fit adjustment before subsequent heat treatment.

[0039] (5) The lug structure of the plug is matched with the small taper of the slot of the filling hole, which has the functions of guiding assembly, initial positioning and self-locking. After the taper angle is less than the friction self-locking angle, the plug will not loosen on its own after pressing. The combination of taper fit design and interference fit design makes the plug stable before welding and significantly improves the process robustness.

[0040] (6) The combination of step positioning and interference fit between the plug and the filling hole can effectively prevent the plug from moving axially and rotating out of place. At the same time, the tapered fit design further enhances the self-centering ability of the plug during insertion, which can effectively prevent the plug from moving in any direction in the filling hole, thereby improving the overall positioning accuracy.

[0041] (7) The special design of the plug and filling hole changes the traditional structure of fixing the plug by the tapered pin, reduces the number of traditional turning surfaces, and makes the disassembly process more streamlined. The assembly personnel only need to press the plug into the positioning to complete the assembly, which significantly shortens the assembly cycle and reduces labor costs. There is no need to process additional structures such as tapered pin holes on the plug and bearing ring, which effectively reduces the processing steps, reduces the complexity of the mold and the difficulty of CNC programming, and is suitable for mass production.

[0042] (8) The overall structure of the plug and filling hole after assembly is heat treated. Based on the special structural design of the plug and filling hole, it can effectively adapt to the geometric changes during heat treatment and processing. The plug fit has good tolerance compensation capability and shows higher pass rate and reliability in actual manufacturing.

[0043] (9) The special design of the plug and filling hole enhances the modularity and standardization of the bearing structure, making it very suitable for integration into automated assembly lines and helping to improve the production efficiency and consistency of the robotics or precision equipment industry. Attached Figure Description

[0044] Figure 1 This is a schematic diagram of the bearing outer ring in this embodiment;

[0045] Figure 2 for Figure 1 A partially enlarged schematic diagram of part A shown;

[0046] Figure 3 This is a schematic diagram of the plug structure in this embodiment;

[0047] Figure 4 for Figure 3 A schematic diagram of the axial projection of the plug shown;

[0048] Figure 5 This is a schematic diagram of the structure of the bearing outer ring and plug after assembly and machining in this embodiment;

[0049] Figure 6 for Figure 5 The diagram shows a cross-sectional view of BB.

[0050] Figure 7 for Figure 6 A partially enlarged schematic diagram of part D is shown below;

[0051] Figure 8 for Figure 5 A magnified view of part C shown;

[0052] Figure 9 This is a schematic diagram of the manufacturing process of the crossed roller bearing in this embodiment. Detailed Implementation

[0053] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0054] In the description of this invention, it should be understood that the terms "upper", "lower", "front", "rear", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0055] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation", "connection" and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, an integral connection, or a detachable connection; they can refer to the internal connection of two components; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0056] This embodiment describes a method for manufacturing a crossed roller bearing, such as... Figure 9 As shown, it includes the following steps:

[0057] S10: Pre-machine the bearing ring and plug 30, wherein the bearing ring and plug 30 are made of the same material.

[0058] The structure of the plug 30 in this embodiment is as follows: Figure 3 , Figure 4 As shown, it includes a columnar segment 31 and a lug structure 32 located at one end of the columnar segment 31, with a first positioning step 33 formed between the columnar segment 31 and the lug structure 32.

[0059] As a special feature of this embodiment, wherein, as Figure 3 , Figure 4 As shown, the projection of the lug structure 32 onto the axial direction of the columnar segment 31 is based on an asymmetrical design of the axis of the columnar segment 31. It should be noted that, in this embodiment, the specific shape of the asymmetry is not limited.

[0060] In this embodiment, the structure of the bearing ring is described using the outer ring 10 as an example. For example, Figure 1 , Figure 2As shown, the outer ring 10 of the bearing is provided with a filling hole 20 that is adapted to the plug 30. The filling hole 20 includes a circular hole 21 adapted to the columnar section 31 and a slot 22 adapted to the lug structure 32. Furthermore, a second positioning step 12 adapted to the first positioning step 33 is formed between the slot 22 and the circular hole 21.

[0061] As a special feature of this embodiment, the lug structure 32 and the slot are fitted with a small taper. Preferably, the taper angle α is 0.5°–7°.

[0062] As a preferred embodiment, in this case, Figure 3 , Figure 4 As shown, the lug structure has at least one plane 34 in its circumferential direction, and in this embodiment, four planes 34 are provided. Correspondingly, the circumferential wall of the slot 22 is provided with a planar structure adapted to the aforementioned planes 34. In this embodiment, the provision of planes 34 increases the stability between the plug and the filling hole in the circumferential direction, effectively preventing rotational misalignment caused by vibration or operational impact.

[0063] S20: Pre-assembly. The plug 30 is pressed into the filling hole 20, and the outer end face of the lug structure 32 on the plug 30 is upset so that the lug structure 32 and the slot 22 are in a slight interference fit.

[0064] Preferably, in this embodiment, the interference fit between the lug structure 32 and the slot 22 is 5μm–50μm.

[0065] S30: Rough machining, which involves rough machining the inner and outer ring surfaces of the assembly formed in S20 by turning. For example... Figures 5-8 As shown, a groove 11 for accommodating the roller is machined at the free end of the columnar section 31 of the plug 30 by rough machining.

[0066] In this embodiment, based on the interference fit between the lug structure and the slot, as well as the axial positioning of the first positioning step and the second positioning step, the position of the plug in the filling hole is relatively stable during the rough machining process, and there will be no displacement, resulting in high machining accuracy.

[0067] S40: Heat treatment. The assembly obtained in S30 is heat-treated to harden it to achieve the required hardness. The required hardness is determined based on the functional requirements of the bearing. An appropriate heat treatment process is selected for the assembly consisting of the plug and the bearing ring. It should be noted that this embodiment does not limit the specific heat treatment process; it depends on the material and application requirements.

[0068] S50: Finishing, the inner and outer ring surfaces of the assembly obtained in S40 are finished to the required precision. It should be noted that in this embodiment, the finishing process can be precision turning, precision grinding, or a combination of precision turning and precision grinding. This embodiment does not limit the specific finishing process.

[0069] S60: Assembly. In this embodiment, the assembly process includes at least the following steps:

[0070] S61: Remove the plug 30 from the assembly obtained from the finishing process in S50.

[0071] S62: Insert the rollers and spacers into the groove between the inner and outer rings of the bearing through the filling hole 20.

[0072] S63, after the roller and spacer block are installed, the plug 30 is installed into the filling hole 20.

[0073] S70: Welding, the plug 30 is welded and fixed to the bearing outer ring 10. Preferably, laser welding is used. After welding, the plug and the bearing outer ring form a whole.

[0074] It should be noted that in this embodiment, the example of setting the filling hole on the outer ring of the bearing is used for illustration. Those skilled in the art should understand that the filling hole can also be set on the inner ring of the bearing.

[0075] A cross roller bearing of this embodiment is manufactured by the cross roller bearing manufacturing method described above.

[0076] In summary, the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for manufacturing a crossed roller bearing, characterized in that, Includes the following steps: S10: Pre-process the bearing ring and plug, wherein the bearing ring and plug are made of the same material; The plug includes a cylindrical section and a lug structure located at one end of the cylindrical section. A first positioning step is formed between the cylindrical section and the lug structure. The projection of the lug structure in the axial direction of the cylindrical section is based on the asymmetric design of the axis of the cylindrical section. The bearing ring is provided with a filling hole adapted to the plug. The filling hole includes a round hole adapted to the columnar section and a slot adapted to the lug structure. A second positioning step adapted to the first positioning step is formed between the slot and the round hole. The lug structure and the slot are fitted with a small taper. S20: Pre-assembly, pressing the plug into the filling hole, and upsetting the outer end face of the lug structure on the plug to make the lug structure and the slot slightly interference fit; S30: Rough machining, which involves rough machining the inner and outer ring surfaces of the assembly formed in S20 by turning. S40: Heat treatment, the assembly obtained in S30 is heat-treated to harden it and obtain the required hardness; S50: Finishing, finishing the inner and outer ring surfaces of the assembly obtained in S40 to the required precision; S60: Assembly, including at least the following steps: S61: Remove the plug from the assembly obtained from the finishing process in S50; S62: Insert the rollers and spacers into the groove between the inner and outer rings of the bearing through the filling hole; S63, After the rollers and spacers are installed, the plug is installed into the filling hole; S70: Welding, the plug is welded to the bearing ring for fixation.

2. The manufacturing method according to claim 1, characterized in that, The interference fit between the lug structure and the slot is 5μm–50μm.

3. The manufacturing method according to claim 1, characterized in that, The taper angle between the lug structure and the slot is 0.5°–7°.

4. The manufacturing method according to claim 1, characterized in that, The bearing ring for the filling hole is either the inner ring or the outer ring.

5. The manufacturing method according to claim 1, characterized in that, The lug structure has at least one plane in its circumferential direction.

6. The manufacturing method according to claim 1, characterized in that, In the S70, laser welding is used for welding.

7. A crossed roller bearing, characterized in that, It is manufactured by the manufacturing method described in any one of claims 1-6.

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