Variable contact rolling-sliding composite bearing and design method

Abstract

This invention discloses a variable contact rolling-sliding composite bearing and its design method, relating to the field of bearing technology. The bearing includes an outer ring, an inner ring, bearing rollers, and a cage. The diameter of the bearing rollers is larger than the axial height of the cage to form an initial clearance. When the external load is small, the bearing rollers bear the load alone, and the bearing is in a pure rolling contact state. When the external load increases to the point that the bearing rollers undergo elastic deformation and the initial clearance closes, the end face of the cage contacts the raceway surface of the outer ring, sharing the load with the bearing rollers, and the bearing switches to a rolling-sliding composite contact state. The design method involves: calculating the roller deformation to determine the critical load; establishing a spring stiffness model for the rollers and cage to solve for the load distribution; checking whether the cage contact stress is lower than the yield limit; if it exceeds the limit, increasing the initial clearance and iteratively optimizing. This invention achieves adaptive switching of the bearing's operating mode, enabling low friction under light loads and high load capacity under heavy loads, and the design method is universal and reliable.

Description

Technical Field

[0001] This invention relates to the field of bearing technology, and in particular to a variable contact rolling-sliding composite bearing and its design method. Background Technology

[0002] Slewing bearings, as core support components of large, heavy-duty rotating equipment, are widely used in engineering machinery, wind power equipment, and other fields. Their load-bearing performance directly determines the operational stability and service life of the entire machine. Under harsh conditions such as heavy loads and large overturning moments, traditional pure rolling slewing bearings rely on line contact between the rollers and raceways to transfer loads. This can easily lead to problems such as excessive local stress on the rollers and insufficient load-bearing capacity, which in turn can cause failure phenomena such as plastic deformation of the rollers, raceway crushing, and stress concentration in the contact area, significantly shortening the service life of the bearing.

[0003] To improve load-bearing capacity, existing technologies typically employ methods such as increasing the number of rollers, enlarging the roller diameter, or optimizing the raceway profile to increase the contact area and reduce contact stress. However, these solutions have the following drawbacks in practical applications: First, increased structural complexity—requires corresponding adjustments to components such as the cage and raceway, significantly increasing machining precision requirements and leading to higher manufacturing costs; second, decreased material utilization—increasing the number or size of rollers directly increases the overall material consumption of the bearing, hindering lightweight design; finally, limited space—simply increasing the number or size of rollers is difficult to achieve when installation space is fixed. Furthermore, under eccentric or impact loads, these solutions still struggle to avoid localized stress concentration, failing to fundamentally resolve the load-bearing bottleneck and cost contradiction in pure rolling bearing mode.

[0004] It is evident that traditional slewing bearings rely solely on the rolling elements to bear external loads, and their load-bearing capacity is limited by the contact fatigue strength of the rolling elements and the surface hardness of the raceway. Therefore, the industry urgently needs to break through the limitations of traditional load-bearing modes and improve the overall load-bearing capacity and failure resistance of slewing bearings through new load-bearing structure designs, while controlling costs and material losses. Summary of the Invention

[0005] The purpose of this invention is to provide a variable contact rolling-sliding composite bearing and its design method to solve the technical problems in the prior art where pure rolling slewing bearings have insufficient load-bearing capacity, are prone to roller plastic deformation and raceway crushing due to line contact stress concentration under heavy load conditions, and simply increasing the number or diameter of rollers will result in complex structure, high processing cost and reduced material utilization.

[0006] The technical solution adopted by the present invention to solve the above-mentioned technical problems is as follows: In a first aspect, the present invention provides a variable contact rolling-sliding composite bearing, comprising an outer ring, an inner ring, a plurality of bearing rollers, and a cage. The bearing rollers are disposed between the inner ring and the outer ring, and the cage is used to accommodate and separate the bearing rollers. The diameter of the bearing rollers is greater than the axial height of the cage, such that there is an initial gap between the end face of the cage and the raceway surface of the outer ring. When the external load is small, the bearing rollers bear the load alone, and the bearing is in a pure rolling contact state. When the external load increases to the point that the bearing rollers undergo elastic deformation and the initial gap closes, the end face of the cage contacts the raceway surface of the outer ring, and shares the load with the bearing rollers, and the bearing switches to a rolling-sliding composite contact state.

[0007] Furthermore, the bearing rollers are cylindrical rollers.

[0008] Furthermore, the cage is made of a pressure-resistant, self-lubricating material.

[0009] Furthermore, the surface of the cage that contacts the bearing roller is provided with a microstructure, which is an array of elliptical micro-pits.

[0010] Secondly, the present invention provides a design method for a variable contact rolling-sliding composite bearing, comprising the following steps: S1, Calculate the elastic deformation of the bearing rollers under Hertzian contact theory based on external load. ; S2, Set the initial clearance between the cage and the outer raceway. When the elastic deformation amount Reaching the initial gap At that time, the critical load that causes the bearing to switch from a pure rolling state to a rolling-sliding composite contact state is determined. ; S3, under the rolling-sliding combined contact state, simplify the bearing rollers and cage as a spring system and calculate the total system stiffness. And based on the total external load Calculate the load borne by the bearing rollers With the load borne by the cage ; S4, based on the load borne by the cage. Calculate the contact stress of the cage ; S5, the contact stress of the cage Yield limit of cage material Compare and determine the initial gap. Does it meet the design requirements? If not, increase the initial gap. Then repeat steps S1 to S4 for iterative optimization.

[0011] Furthermore, in step S1, the elastic deformation of the bearing rollers... Calculate using the following formula: in, The load borne by a single roller, in N. The effective contact length of the rollers, in meters. The elastic modulus of bearing steel. For bearing steel, Poisson's ratio The equivalent radius of curvature of the contact pair, in meters. The contact half-width is in meters (m).

[0012] Furthermore, in step S2, the critical load Calculate using the following formula: in, This is the critical load, in N. The initial gap is expressed in meters (m).

[0013] Furthermore, in step S3, the overall system stiffness Calculate using the following formula: in, To accommodate the number of bearing rollers, This represents the equivalent stiffness of the bearing rollers. To maintain the equivalent stiffness of the frame; Total external load The load borne by the bearing rollers The load borne by the cage satisfy: The load distribution ratio between the bearing rollers and the cage satisfies: .

[0014] Furthermore, in step S4, the contact stress of the cage... Calculate using the following formula: in, The projected contact area between cage 4 and outer ring 1 raceway is expressed in m². 2 .

[0015] Furthermore, in step S5, the judgment condition for meeting the design requirements is: in, For safety factor; If this condition is not met, then increase the initial gap. And recalculate and verify.

[0016] According to the above technical solution, the beneficial effects of the present invention are: 1. This invention, by setting an initial clearance between the bearing rollers and the cage, enables the bearing to automatically switch between pure rolling and rolling-sliding combined modes according to the magnitude of the external load. When the external load is small, the elastic deformation of the bearing rollers is less than the initial clearance, the cage does not participate in load bearing, and the bearing is in a pure rolling state, resulting in low frictional resistance and high operating efficiency. When the external load increases, the clearance between the cage and the raceway gradually decreases. When the clearance is zero, the initial clearance closes, the end face of the cage contacts the raceway surface and participates in load bearing, and the bearing switches to a rolling-sliding combined friction state. Utilizing the large contact area and high damping characteristics of the cage, the load-bearing capacity and impact resistance are significantly improved. Through the combination and switching of the two modes, a single bearing can achieve the optimal solution for all operating conditions, achieving low friction and high efficiency under light loads and high load-bearing capacity and high reliability under heavy loads, greatly expanding the reliable operating range of the bearing. Under heavy load conditions, sliding contact can effectively disperse stress, avoiding early fatigue pitting and crushing of the bearing rollers and raceways; under starting conditions, it avoids the severe wear problems common in pure sliding bearings.

[0017] 2. The design method provided by this invention, which calculates the elastic deformation of bearing rollers based on external load and then deduces the initial clearance between the cage and bearing rollers, is not only applicable to the bearing structure of this invention, but can also be widely extended to other types of rolling bearings, providing new theoretical basis and technical means for bearing design in high load and variable working condition application scenarios.

[0018] 3. The present invention provides an array of elliptical micro-dimples on the surface of the cage that contacts the bearing rollers. Compared with ordinary circular microtextures, elliptical micro-dimples can form a thicker local oil film, significantly reducing the coefficient of friction; at the same time, the large radius of curvature of the elliptical edge can reduce the peak value of residual tensile stress on the surface, inhibit crack initiation, thereby improving the fatigue life and operational reliability of the bearing.

[0019] 4. The cage in this invention is made of a pressure-resistant self-lubricating material. When the end face of the cage contacts the raceway and forms sliding friction, the self-lubricating material continuously migrates to the contact surface and forms a stable lubricating film, realizing a "self-replenishing" lubrication mechanism, which effectively improves the bearing life, while also having the advantages of low friction coefficient and low noise. Attached Figure Description

[0020] Figure 1This is a schematic diagram of the structure of the present invention; Figure 2 This is a partially enlarged schematic diagram of the bearing rollers and cage. Figure 3 A schematic diagram of a localized elliptical micro-dimple on the cage.

[0021] The markings in the diagram are: 1. Outer ring, 2. Bearing roller, 3. Inner ring, 4. Cage, 41. Microstructure. Detailed Implementation

[0022] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0023] The structures, proportions, sizes, etc., shown in the accompanying drawings of this specification are only for the purpose of assisting those skilled in the art in understanding and reading the content disclosed in the specification, and are not intended to limit the conditions under which the present invention can be implemented. Therefore, they have no substantial technical significance. Any modifications to the structure, changes in the proportions, or adjustments to the size, without affecting the effects and objectives that the present invention can produce, should still fall within the scope of the technical content disclosed in the present invention.

[0024] It should also be noted that, unless otherwise stated, "several" means two or more; the terms "upper" and "lower," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing the present 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, and therefore should not be construed as a limitation of the present invention. Changes or adjustments to the relative relationships, without substantially altering the technical content, should also be considered as within the scope of the present invention.

[0025] Example 1

[0026] like Figures 1 to 2 As shown, this embodiment provides a variable contact roller-slider composite bearing. The bearing includes an outer ring 1, an inner ring 3, a plurality of bearing rollers 2, and a cage 4.

[0027] The bearing rollers 2 are disposed between the inner ring 3 and the outer ring 1. The cage 4 is used to accommodate and separate the bearing rollers 2, ensuring that the bearing rollers 2 are evenly distributed in the circumferential direction. The bearing rollers 2 are cylindrical rollers, and the axial height of the cage 4 is smaller than the diameter of the bearing rollers 2. When the bearing rollers 2 are installed in the cage 4, there is an initial gap between the end face of the cage 4 and the raceway surface of the outer ring 1. See details Figure 2 Enlarged view of a specific area.

[0028] The cage 4 is made of a material with good compressive strength and self-lubricating properties. The surface of the cage 4 that contacts the bearing roller 2 has a microstructure 41. Specifically, as shown... Figure 3 As shown, the microstructure 41 is an array of elliptical micro-pits. These elliptical micro-pits can store a small amount of lubricating oil or grease, and can continuously release lubricant when the bearing enters sliding contact, effectively reducing frictional resistance and frictional wear. Compared with ordinary circular microtextures, elliptical micro-pits can form a thicker local oil film, and their large radius of curvature at the edges can reduce residual tensile stress on the surface and inhibit crack initiation.

[0029] Based on the above structure, the operating mode of the bearing described in this embodiment is as follows: When the external load is small, the elastic deformation caused by the load applied to the bearing roller 2 Smaller than the initial gap Time (i.e.) At this time, the end face of the cage 4 does not contact the raceway surface and does not participate in bearing the load. Only the bearing roller 2 bears the entire load and relies on the rolling of the bearing roller 2 itself to transmit the load. The bearing exhibits a pure rolling contact state, which has the advantages of low frictional resistance and high operating efficiency.

[0030] When the external load continues to increase, the elastic deformation of bearing roller 2 is... Reaching and exceeding the initial gap Time (i.e.) The initial gap is closed. At this point, the end face of the cage 4 begins to contact the raceway surface and bear the load. The bearing rollers 2 and the cage 4 share the external load, and the friction state changes from the original pure rolling friction to a rolling-sliding composite friction state. In this state, the bearing retains some of the advantages of rolling friction, and the larger contact area provided by the cage 4 disperses stress, significantly improving the overall load-bearing capacity and impact resistance of the bearing.

[0031] Example 2

[0032] This embodiment provides a design method for the variable contact roller-slider composite bearing described in Embodiment 1, specifically a method for determining the initial clearance between the bearing roller 2 and the cage 4 based on external load. The verification and design method is described, which involves quantitative analysis and design through the following five stages.

[0033] This embodiment uses a specific set of design parameters as an example for calculation and explanation. The relevant parameters are as follows: Phase 1: External Load Application Phase (Pure Rolling Phase) An initial external load is applied to the bearing roller 2, and at this time there is an initial clearance between the cage 4 and the raceway of the outer ring 1. Under load, bearing roller 2 undergoes elastic deformation, and its deformation behavior conforms to Hertzian contact theory. For rolling bearings made of bearing steel, the elastic deformation of bearing roller 2... Calculate using the following formula: in, The load borne by a single roller, in N. The effective contact length of the rollers, in meters. The elastic modulus of bearing steel. For bearing steel, Poisson's ratio The equivalent radius of curvature of the contact pair, in meters. From the composite curvature Decide, This embodiment is based on practical engineering experience. Take 100, =0.01m, The contact half-width is in meters and is calculated using Hertzian theory.

[0034] When the bearing roller deformation Smaller than the initial gap At that time, that is At this time, the cage 4 is completely unloaded, and the system behaves as a pure rolling structure.

[0035] In this embodiment, the initial external load =5kN, substituting into the Hertzian contact formula, the roller deformation is calculated as follows: =2.19μm. Because < At this time, the cage 4 is not under stress, and the system is in a pure rolling state.

[0036] Phase 2: Gap Closure Phase (Critical Load for Entering Roll-Slide Combination) When the external load increases, the elastic deformation of bearing roller 2 increases. Reaching the initial gap At this point, the system enters the critical point of a combined roll-slip state, and the critical load at this point is... It can be derived by reverse calculation from the transformation formula in stage 1: In this embodiment, =5μm, calculated critical load : Substitution The value can be calculated using the formula: =10.6kN When the external load is greater than or equal to the critical load, the cage 4 begins to make microscopic contact with the raceway of the outer ring 1, and the bearing enters a rolling-sliding composite contact state.

[0037] Phase 3: Cooperative Deformation Phase (Roll-Slide Coupling) In the rolling-sliding combined state, the bearing roller 2 is simplified as a stiffness of The spring simplifies the cage 4 into a spring with a stiffness of The spring, then the total stiffness of the entire bearing system for: in, The number of bearing rollers is set to 8. =5 10 8 N / m, =1 10 9 N / m. The total system stiffness in this embodiment is calculated to be... =5 10 9 N / m.

[0038] At this time, the total external load borne by the bearing equal to the load borne by bearing roller 2 The load borne by cage 4 sum: The load distribution ratio between bearing roller 2 and cage 4 satisfies: The ratio is calculated to be approximately 4 when the external load is 15 kN. =12kN, =3kN.

[0039] Initially, during the initial composite stage, bearing roller 2 remains the primary load-bearing element. However, as the external load continues to increase, the deformation of bearing roller 2 intensifies, and the load borne by cage 4 shifts. Its proportion will increase rapidly, thereby significantly improving the overall load-bearing capacity of the bearing.

[0040] Phase 4: Static Equilibrium State (Cage Stress Check) To ensure the safe operation of the bearing, the contact stress of cage 4 must be controlled. Perform verification.

[0041] Contact stress of cage 4 : in, The projected contact area between cage 4 and outer ring 1 raceway is expressed in m². 2 In this embodiment, =4 10 -4 m 2 Substitute =120kN, the calculated contact stress currently borne by cage 4 is... =300MPa.

[0042] Phase 5: Yield Limit Verification and Gap Optimization Based on the yield strength of the cage 4 material, determine the initial clearance between the cage 4 and the bearing roller 2 under a given external load. Is the design reasonable? Assume the yield strength of the cage material is... Then it must satisfy: in The safety factor is determined based on actual working conditions. The calculated cage contact stress is then used. Its yield strength Compare them.

[0043] In this embodiment, =1, =300MPa, =518.42 ,Right now Cage 4 is in a safe state and has not been crushed; the initial clearance... The 5μm design is reasonable.

[0044] In actual design, calculations should be performed based on the maximum ultimate external load to ensure that the cage 4 does not undergo plastic deformation under extreme working conditions.

[0045] If the verification result does not satisfy the above inequality, that is This indicates that cage 4 is at risk of overload collapse. In this case, the initial clearance should not be simply reduced. Instead, it should be appropriately increased. Increase This will result in the bearing roller 2 needing to produce a larger amount of elastic deformation under the same external load. This allows the cage 4 to participate in load bearing, thereby allowing the bearing rollers 2 to bear more load and reducing the load shared by the cage 4. This causes its contact stress The gap is reduced to within the permissible range. Through this iterative optimization, the most suitable initial gap can be precisely determined. This ensures that the external load is optimally distributed between the bearing rollers 2 and the cage 4, thereby maximizing the bearing life and reducing the risk of failure.

[0046] It should be noted that the above embodiments are only for illustrating the technical concept and features of the present invention, and are intended to enable those skilled in the art to understand the content of the present invention and implement it accordingly. They should not be used to limit the scope of protection of the present invention. All equivalent changes or modifications made in accordance with the spirit and essence of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A variable contact rolling-sliding composite bearing, characterized in that: It includes an outer ring (1), an inner ring (3), a plurality of bearing rollers (2) and a cage (4), wherein the bearing rollers (2) are disposed between the inner ring (3) and the outer ring (1), and the cage (4) is used to accommodate and separate the bearing rollers (2). The diameter of the bearing roller (2) is greater than the axial height of the cage (4), so that there is an initial gap between the end face of the cage (4) and the raceway surface of the outer ring (1); When the external load is small, the bearing roller (2) bears the load alone, and the bearing is in a pure rolling contact state; when the external load increases to the point that the bearing roller (2) undergoes elastic deformation and the initial gap closes, the end face of the cage (4) contacts the raceway surface of the outer ring (1) and bears the load together with the bearing roller (2), and the bearing switches to a rolling-sliding composite contact state.

2. The variable contact rolling-sliding composite bearing according to claim 1, characterized in that: The bearing roller (2) is a cylindrical roller.

3. The variable contact rolling-sliding composite bearing according to claim 1, characterized in that: The cage (4) is made of a pressure-resistant, self-lubricating material.

4. The variable contact rolling-sliding composite bearing according to claim 1, characterized in that: The surface of the cage (4) that contacts the bearing roller (2) is provided with a microstructure (41), which is an array of elliptical micro-pits.

5. A design method for a variable contact rolling-sliding composite bearing, characterized in that: Includes the following steps: S1, Calculate the elastic deformation of the bearing roller (2) under Hertzian contact theory based on the external load. ; S2, set the initial clearance between the cage (4) and the outer ring (1) raceway. When the elastic deformation amount Reaching the initial gap At that time, the critical load that causes the bearing to switch from a pure rolling state to a rolling-sliding contact state is determined. ; S3, under the rolling-sliding combined contact state, the bearing roller (2) and cage (4) are simplified into a spring system, and the total stiffness of the system is calculated. And based on the total external load Calculate the load borne by the bearing roller (2) The load borne by the cage (4) ; S4, based on the load borne by the cage (4) Calculate the contact stress of the cage (4) ; S5, the contact stress of the cage (4) Yield limit of cage (4) material Compare and determine the initial gap. Does it meet the design requirements? If not, increase the initial gap. Then repeat steps S1 to S4 for iterative optimization.

6. The design method according to claim 5, characterized in that: In step S1, the elastic deformation of the bearing roller (2) Calculate using the following formula: in, The load borne by a single roller, in N. The effective contact length of the rollers, in meters. The elastic modulus of bearing steel. For bearing steel, Poisson's ratio denoted by , where is the equivalent radius of curvature of the contact pair in meters (m), and b is the contact half-width in meters (m).

7. The design method according to claim 5, characterized in that: In step S2, the critical load Calculate using the following formula: in, This is the critical load, in N. The initial gap is expressed in meters (m).

8. The design method according to claim 5, characterized in that: In step S3, the overall stiffness of the system Calculate using the following formula: in, To accommodate the number of bearing rollers, The equivalent stiffness of the bearing roller (2) is given. To maintain the equivalent stiffness of the cage (4); Total external load The load borne by the bearing roller (2) The load borne by the cage (4) satisfy: The load distribution ratio between the bearing roller (2) and the cage (4) satisfies: .

9. The design method according to claim 5, characterized in that: In step S4, the contact stress of the cage (4) Calculate using the following formula: in, The projected contact area between cage 4 and outer ring 1 raceway is expressed in m². 2 .

10. The design method according to claim 5, characterized in that: In step S5, the condition for satisfying the design requirements is as follows: in, For safety factor; If this condition is not met, then increase the initial gap. And recalculate and verify.

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