Rolling bearing and method for manufacturing same

Abstract

Disclosed is a rolling bearing comprising at least one outer ring (1), at least one inner ring (2) and at least one rolling element (3) arranged between the at least one outer ring (1) and the at least one inner ring (2) wherein an outer surface of the at least one outer ring (1) is configured to fit into a first element and an outer surface of the at least one inner ring (2) is configured to fit into a second element. An inner surface of the outer ring (1) is configured to fit to a first element, an inner surface of the inner ring (2) is configured to fit to a second element, and the first element and the second element are rotatable relative to each other wherein a polymer composite sheet layer (6) is bonded to at least one of an outer surface of the outer ring (1) and the inner surface of the inner ring (2) using a bonding agent, wherein the polymer composite sheet layer comprises at least one perfluoroalkyl and / or polyfluoroalkyl component.

Description

Technical Field

[0001] The invention relates to a rolling bearing. In addition, the invention relates to a method for producing a rolling bearing. Background Art

[0002] Many rotating mechanical devices may include rolling bearings that enable relative rotation between a first element and a second element. For example, the first element may be a housing and the second element may be a rotating shaft, wherein the outer ring of the rolling bearing is fitted into the housing and / or the inner ring of the rolling bearing is fitted onto the shaft. Depending on the specific application, it may happen that either due to a load that deforms the ring or due to design, one of these fits is a loose fit, which may cause the ring to creep.

[0003] In some cases, this ring creep may cause so-called ring creep wear damage. For example, if a steel outer ring is loosely fitted into an aluminum alloy housing, the ring creep of the outer ring has the opportunity to cause ring creep wear damage on the aluminum alloy housing due to the relative movement between the outer ring and the housing (ring creep movement). In other words, the outer diameter surface of the outer ring and the inner surface of the housing rub against each other, causing wear on the housing. When the wear of the housing increases, backlash may occur in the rotating support part, resulting in abnormal vibration and out of order of the rotating mechanical equipment. This may further lead to a loss of alignment, which may cause undesirable noise. In addition, creep wear may cause debris and / or contaminants, which may damage components of the bearing and / or mechanical equipment, such as gears, which may shorten the life of the bearing and / or mechanical equipment.

[0004] This ring creep movement can be prevented by interlocking or rubber O-rings. However, in practice, interlocking mechanisms and rubber O-rings are not an ideal solution because it is difficult to implement and / or unreliable. Polymer coatings of the friction surfaces ( / rubbing surfaces) consisting of solid lubricants and a manganese-phosphating (i.e. MnPh) pretreatment are another alternative to reduce creep wear. So far, the coatings consist of antimony (Sb), which is considered a material toxic to human health, and the necessary coating process ( / treatment) is very complicated because the entire bearing needs to be immersed in an acid liquid bath for the manganese-phosphating process ( / treatment) and the thermal curing of the polymer coating.

[0005] Therefore, the object of the present invention is to provide a measure for reducing creep wear damage, overcoming the above-mentioned disadvantages. Summary of the invention

[0006] This object is achieved by a rolling bearing according to claim 1 and a method for producing a rolling bearing according to claim 12 .

[0007] Hereinafter, a rolling bearing is provided, which includes at least one outer ring, at least one inner ring, and at least one rolling element arranged between the at least one outer ring and the at least one inner ring. The outer surface of the at least one outer ring is configured to be assembled into a first element (such as a housing), and the inner surface of the inner ring is configured to be assembled into a second element (such as a shaft), wherein the first element and the second element are rotatable relative to each other.

[0008] The outer surface of the at least one outer ring may be the outer surface of the ring in the radial direction of the bearing, such as the outer circumferential surface of the outer ring. The inner surface of the at least one inner ring may be the inner surface of the ring in the radial direction of the bearing, such as the inner hole of the inner ring. For example, the rolling bearing may be a ball bearing, a cylindrical roller bearing, a tapered roller bearing, etc. In addition, the outer ring and / or the inner ring may be made of a first material. The first material may be steel, in particular bearing steel. The first element and / or the second element may be made of a second material different from bearing steel. In particular, the second material may be softer than the first material. For example, the second material may be aluminum, an aluminum alloy, etc. In addition, the roller bearing may be used in an electric motor, such as an electric vehicle, or a pump.

[0009] In order to reduce creep wear and manufacturing costs, a polymer composite sheet layer is bonded to at least one of the outer surface of the outer ring and the inner surface of the inner ring using a bonding agent, wherein the polymer composite sheet layer includes at least one perfluoroalkyl and / or polyfluoroalkyl component (PFAS, perfluoroalkyl substances and polyfluoroalkyl substances). The perfluoroalkyl and / or polyfluoroalkyl component can be an organofluorine chemical compound having at least one fluorine atom attached to an alkyl chain, such as polytetrafluoroethylene (PTFE), polyperfluoroethylenepropylene (FEP) and / or perfluoroalkoxy (FPA). Such a polymer composite sheet layer can reduce wear on the elements assembled to the outer ring and / or the inner ring, so that abnormal vibration and / or noise can be reduced. In addition, the polymer composite sheet layer or the liner can be cut to a certain size before bonding the polymer composite sheet layer to the surface, which can reduce manufacturing costs. In particular, the coating process can be omitted. Furthermore, if the polymer composite sheet layer becomes worn, the polymer composite sheet may be replaced.

[0010] For example, the polymer composite sheet layer may be made of polytetrafluoroethylene (PTFE), polyperfluoroethylenepropylene (FEP) and / or perfluoroalkoxy (FPA). In particular, these compounds may exhibit self-lubricity and may have high wear resistance. In addition, these compounds may be commercially available as sheet material that only needs to be cut to size, thereby omitting the expensive coating process.

[0011] In addition, the polymer composite sheet layer may include a polytetrafluoroethylene (PTFE) polymer impregnated carrier, wherein the carrier is a glass and / or polyester carrier. Such a PTFE impregnated carrier has the advantage that it may have increased durability and / or may be commercially available as a sheet material that only needs to be cut to size, thereby omitting an expensive coating process.

[0012] Preferably, the polymer composite sheet layer comprises a polymer and 1-50 wt%, preferably 5-20 wt%, of at least one solid lubricant, wherein the polymer is polyperfluoroethylene propylene ( / fluoroethylene propylene) (FEP), perfluoroalkoxy (FPA), polyetheretherketone (PEEK), polyphenylene sulfide (PPS), polyester (PET), polyurethane (TPU), polyethylene (PE), polypropylene (PP), polyimide (PI), and / or polyamideimide (PAI). For example, the solid lubricant can be polytetrafluoroethylene (PTFE). Due to the polytetrafluoroethylene (PTFE) that can be used as a solid lubricant, the amount of wear on the outer ring and / or inner ring surface and / or the first element and / or the second element can be reduced, which can also reduce the amount of debris. This can reduce damage to components of the bearing and / or mechanical equipment (such as gears), which can lead to a longer life of the bearing and / or mechanical equipment.

[0013] The thickness of the polymer composite sheet layer can be between 2 and 200 μm, preferably between 5 and 30 μm. When the layer thickness is less than 2 μm, the polymer composite sheet layer may wear at an early stage and the creep wear resistance may not be maintained for a long time. On the other hand, when the film thickness exceeds 200 μm, the strength of the polymer composite sheet layer may be reduced, so that the polymer composite sheet layer may peel off. Therefore, a layer thickness between 2 and 200 μm allows effective reduction of creep wear and reduces the risk of peeling of the polymer composite sheet layer.

[0014] Preferably, the bonding agent is an adhesive epoxy or cyanoacrylate glue. For example, the epoxy glue may be air-hardening, UV-hardening and / or curing-hardening.

[0015] Furthermore, the bonding agent may be applied as a bonding layer with a thickness of less than 25 μm, preferably less than 5 μm. This allows for a strong bonding of the polymer composite sheet layer to the surface.

[0016] Additionally or alternatively, the polymer composite sheet layer may be provided with an adhesive on one side, wherein the adhesive is an acrylic adhesive or a silicone. Thus, the polymer composite sheet layer may be bonded to at least one of the outer surface of the outer ring and the inner surface of the inner ring without applying a bonding agent in an additional bonding layer. This may reduce manufacturing costs.

[0017] Preferably, before applying the polymer composite sheet layer, the surface roughness of the outer surface of the outer ring and / or the inner surface of the inner ring has a surface roughness Ra of 0.5 μm to 10 μm, preferably 1 μm to 3 μm. This allows improving the bonding of the polymer composite sheet layer on the outer surface of the outer ring and / or the inner surface of the inner ring. Preferably, the back side ( / backside) of the polymer composite sheet layer is pretreated using chemical etching and / or plasma etching. This can improve the bonding of the binder to the polymer composite sheet layer.

[0018] Preferably, the friction coefficient when in dry contact with aluminum alloy is between 0.05 and 0.4. In particular, a lower friction coefficient can indicate a lower amount of creep wear.

[0019] According to another preferred embodiment, the polymer composite sheet layer has a dielectric strength greater than 15 kV / mm and a dielectric constant or relative permittivity lower than 4.

[0020] In the case of rolling bearings used in electric motors (for example in electric vehicles), it may happen that current flows through the bearings and / or voltage is applied to the rolling bearings. Due to the leakage of current through the bearings, the lubricant in the bearings and / or the bearings, in particular the metal surfaces of the bearings, such as the raceways for rolling elements, may be damaged. The damage may include an increase in surface roughness and / or noise, and may impair the bearing function. By providing a polymer composite sheet layer for the outer surface of the outer ring and / or the inner surface of the inner ring, the composite coating can have a dielectric strength greater than 15 kV / mm and a dielectric constant less than 4, the current passing intensity can be significantly reduced, for example greater than 90%, and the service life of the bearing is extended. The relatively high dielectric strength and low dielectric constant of the coating can reduce the current intensity and bearing damage.

[0021] According to another aspect of the present invention, a method for manufacturing a rolling bearing as described above is provided. The method comprises the following steps:

[0022] providing a polymer composite sheet layer, wherein the polymer composite sheet layer comprises at least one per-and / or polyfluoroalkyl component,

[0023] applying a bonding agent on at least one of the outer surface of the outer ring and the inner surface of the inner ring and / or the polymer composite sheet layer, and

[0024] The polymer composite sheet layer is bonded to at least one of the outer surface of the outer ring and the inner surface of the inner ring.

[0025] According to another embodiment, the method further comprises, before applying the polymer composite sheet layer, preparing at least one (or one) of the outer surface of the outer ring and the inner surface of the inner ring to have a surface roughness Ra of 0.5 to 10 μm, preferably Ra of 1 to 3 μm. This allows to improve the bonding of the polymer composite sheet layer on the outer surface of the outer ring and / or the inner surface of the inner ring. Preferably, the back side of the polymer composite sheet layer is pretreated using chemical etching and / or plasma etching. This can improve the bonding of the binder to the polymer composite sheet layer.

[0026] Further preferred embodiments are defined in the dependent claims as well as in the description and the drawings.Therefore, elements described or shown in combination with other elements may exist alone or in combination with other elements without departing from the scope of protection. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In the following, preferred embodiments of the present invention are described in conjunction with the accompanying drawings, wherein the accompanying drawings are only exemplary and are not intended to limit the scope of protection. The scope of protection is limited only by the accompanying claims.

[0028] These figures show:

[0029] Figure 1 : depicts a cross-sectional view of an example of a rolling bearing according to an embodiment of the present invention,

[0030] Figure 2 : Figure obtained in the experiment, depicting the aluminum wear depth of different polymer composite sheet layers, and the reference example,

[0031] Figure 3 : Graphs obtained in the experiment, depicting the wear depth of the polymer composite sheet layer for different polymer composite sheet layers, and a reference example, and

[0032] Figure 4 : Graphs obtained in the experiments depicting the friction coefficients of different polymer composite sheet layers, and reference examples.

[0033] Description of Reference Numerals

[0034] 1 Outer ring

[0035] 1a Outer raceway

[0036] 1b Outer surface

[0037] 2Inner ring

[0038] 2a Inner raceway

[0039] 3 Rolling elements

[0040] 5. Binding layer

[0041] 6 polymer composite sheet layers DETAILED DESCRIPTION

[0042] In the following, identical or similar functional elements are denoted by the same reference numerals.

[0043] In the present invention, the type of rolling bearing 10 is not limited. Figure 1 The ball bearing shown is exemplified. The ball bearing includes: an outer ring 1 having an outer ring raceway 1a, an inner ring 2 having an inner ring raceway 2a, and a plurality of balls 3 arranged between the two raceways 1a, 2a. In addition, the outer diameter surface ( / outer diameter surface) 1b of the outer ring 1 of the ball bearing is assembled to a housing ( / seat) (housing) (not shown), and the inner peripheral surface (inner peripheral surface) of the inner ring 2 is assembled to a shaft member (not shown).

[0044] The outer ring 1 and the inner ring 2 are made of metal, such as bearing steel. In addition, the outer diameter surface 1b of the outer ring 1 is provided with a bonding layer 5 including a bonding agent, which bonds the polymer composite sheet layer 6 to the outer diameter surface 1b of the outer ring 1. In many cases, the housing is made of aluminum or an aluminum alloy (e.g., an aluminum die-cast material) to reduce weight. Since the polymer composite sheet layer 6 of the present invention is softer than aluminum or an aluminum alloy (e.g., an aluminum die-cast material), even if the outer diameter surface 1b of the outer ring and the housing can move relative to each other, the housing will not be damaged.

[0045] The polymer composite sheet layer 6 includes a polymer such as polyperfluoroethylene propylene ( / fluoroethylene propylene) (FEP), perfluoroalkoxy (FPA) and / or polytetrafluoroethylene (PTFE). Additionally or alternatively, a polymer composite sheet layer 6 including polyetheretherketone (PEEK), polyphenylene sulfide (PPS), polyester (PET), polyurethane (TPU), polyethylene (PE), polypropylene (PP), polyimide (PI) and / or polyamideimide (PAI) and at least one solid lubricant can be used.

[0046] If a solid lubricant is added to the polymer composite sheet layer 6, the solid lubricant needs to have lubricating properties and needs to be softer than aluminum or an aluminum alloy which is a representative material of the housing. As the solid lubricant, polytetrafluoroethylene (PTFE) and / or molybdenum disulfide (MoS2) can be used. The content of the solid lubricant in the polymer composite sheet layer 6 may be between 1 and 50 wt% (i.e., weight percentage, also referred to as weight %), preferably between 5 and 20 wt%.

[0047] As another option, the polymer composite sheet layer is made of polytetrafluoroethylene (PTFE) and / or includes a polytetrafluoroethylene (PTFE) polymer impregnated carrier, wherein the carrier is a glass and / or polyester carrier.

[0048] The polymer composite sheet layer 6 can be formed by an extrusion method. For example, the raw materials for polymer composite (such as the polymer or polymer mixture used) are dissolved and then flow cast ( / flowcasted), for example, using drum casting (drum cast). The obtained cast material is then stretched forward and / or laterally to a predetermined size, and finally rolled (rolled) to obtain a roll of polymer composite sheet material. This material can then be cut into the desired size. Additives (such as solid lubricants) can be added at the beginning of the extrusion method when the raw materials are dissolved and mixed and / or the additives are coated ( / coated) on the sheet by using a coating method (coating method).

[0049] As a bonding agent, an adhesive epoxy or cyanoacrylate glue can be used. The thickness of the bonding layer 5 is less than 25 μm, preferably less than 5 μm, and can be directly applied to the outer diameter surface 1b of the outer ring. As another option, the polymer composite sheet layer 6 is provided with an adhesive on one side, wherein the adhesive is an acrylic adhesive or silicone.

[0050] Before the polymer composite sheet layer 6 is applied to the outer ring 1, the surface roughness of the outer ring 1 is machined to have a surface roughness Ra of 0.5 to 10 μm, preferably 1 to 3 μm. This allows for improved bonding of the bonding layer 5 on the surface. Then, the polymer composite sheet layer 6 is applied to the bonding layer 5. Preferably, the polymer composite sheet layer 6 can be cut to a certain size before it is bonded to the outer ring 1.

[0051] The thickness of the polymer composite sheet layer 6 is between 2 and 200 μm. When the thickness of the polymer composite sheet layer 6 is less than 2 μm, the polymer composite sheet layer 6 wears at an early stage and cannot maintain creep wear resistance for a long time. On the other hand, when the thickness of the polymer composite sheet layer 6 exceeds 200 μm, the strength of the polymer composite sheet layer 6 decreases, so that the polymer composite sheet layer 6 may peel ( / peel off). The thickness of the polymer composite sheet layer 6 is more preferably 5 μm to 30 μm.

[0052] As another alternative, the polymer composite sheet layer 6 may be bonded to the inner surface of the inner ring 2 when creep occurs in the inner ring and the shaft.

[0053] The present invention will be further described with reference to experimental examples. However, it should be noted that the present invention is not limited thereto.

[0054] In this experiment, the desired effect of the binding membrane of the present invention was verified.

[0055] As shown in Table 1, as Example 1, a sheet material made of polytetrafluoroethylene (PTFE) and polyester was used, and as Example 2, a sheet material made of fluoroethylene propylene (FEP) was used.

[0056] For the test, a pin on disk test was performed, in which a pin was moved on a disk for a predetermined amount of time with a defined load and a defined contact pressure. This allowed the wear depth and the average friction coefficient to be determined. Two groups of tests were performed, in which in the first group a steel pin was moved on an aluminum disk and in the second group an aluminum pin was moved on a steel disk. In both groups, the steel components, i.e. the pins in the first group and the disks in the second group, were provided with polymer composite sheet layers according to Examples 1 and 2. In addition, uncoated reference samples were prepared. The polymer composite sheet layers were bonded to the workpieces with epoxy resin or cyanoacrylate. As reference samples, coatings containing a binder, molybdenum disulfide (MoS2) as a solid lubricant and antimony according to the prior art as described, for example, in EP3505783A1 were used.

[0057] The diameter of the steel pin is 82 mm and the diameter of the aluminum pin is 64 mm. The defined load for the steel pin is 20 N and the defined load for the aluminum pin is 10 N, with an average contact pressure of 130 MPa for the steel pin and 124 MPa for the aluminum pin. The results of the wear depth and average friction coefficient of the aluminum (Al) and polymer composite sheet layers are given in Figures 2 to 4 Shown in.

[0058] Example No. Solid lubricant type polymer 1 PTFE+Polyester 2 FEP Reference <![CDATA[MoS2,Sb2O3]]> - Uncoated - -

[0059] from Figure 2 and Figure 3 It can be seen that the wear on the aluminum and polymer composite sheet layer can be significantly reduced and is significantly less than the reference coating. Regarding the average friction coefficient, from Figure 4 It can be seen that, depending on the polymer used, the average friction coefficient is at least comparable to the reference coating, or even lower than the reference coating.

[0060] In summary, the polymer composite sheet layer 6 described can reduce wear on an element (such as an aluminum housing) assembled to an outer ring and / or an inner ring, so that abnormal vibration and / or noise can be reduced. The polymer composite sheet layer 6 described has a low coefficient of friction, which can allow the amount of debris to be reduced, resulting in a longer life of the bearing and / or mechanical equipment.

[0061] In addition, the polymer composite sheet layer 6 can be cut to size before being bonded to the metal surface of the outer ring and / or the inner ring. The bonding agent can be applied as a bonding layer and / or applied to one side of the polymer composite sheet layer 6.

Claims

1. A rolling bearing (10), comprising at least one outer ring (1), at least one inner ring (2) and at least one rolling element (3) arranged between the at least one outer ring (1) and the at least one inner ring (2), wherein: The outer surface of at least one outer ring (1) is configured to be assembled into a first element, the inner surface of the inner ring (2) is configured to be assembled into a second element, and the first element and the second element are capable of rotating relative to each other, wherein a polymer composite sheet layer (6) is bonded to at least one of the outer surface of the outer ring (1) and the inner surface of the inner ring (2) using a binder, wherein the polymer composite sheet layer contains at least one perfluoroalkyl and / or polyfluoroalkyl component.

2. The rolling bearing (10) according to claim 1, characterized in that: The thickness of the polymer composite sheet layer (6) is between 2 μm and 200 μm, preferably between 5 μm and 30 μm.

3. The rolling bearing (10) according to claim 1 or 2, characterized in that: The polymer composite sheet layer (6) is made of polytetrafluoroethylene (PTFE), polyperfluoroethylene propylene (FEP) and / or perfluoroalkoxy (FPA).

4. The rolling bearing (10) according to any one of the preceding claims, characterized in that The polymer composite sheet layer (6) comprises a polytetrafluoroethylene (PTFE) polymer impregnated carrier, wherein the carrier is a glass and / or polyester carrier.

5. Rolling bearing (10) according to any one of the preceding claims, characterized in that The polymer composite sheet layer (6) comprises a polymer and 1-50wt%, preferably 5-20wt% of at least one solid lubricant, wherein the polymer is polytetrafluoroethylene (FEP), perfluoroalkoxy (FPA), polyetheretherketone (PEEK), polyphenylene sulfide (PPS), polyester (PET), polyurethane (TPU), polyethylene (PE), polypropylene (PP), polyimide (PI) and / or polyamideimide (PAI), wherein preferably the solid lubricant is polytetrafluoroethylene (PTFE).

6. Rolling bearing (10) according to any one of the preceding claims, characterized in that The bonding agent is a viscous epoxy or cyanoacrylate glue.

7. Rolling bearing (10) according to any one of the preceding claims, characterized in that The bonding agent is applied as a bonding layer (5) with a thickness of less than 25 μm, preferably less than 5 μm.

8. Rolling bearing (10) according to any one of the preceding claims, characterized in that The polymer composite sheet layer (6) is provided with an adhesive on one side, wherein the adhesive is an acrylic adhesive or silicone.

9. Rolling bearing (10) according to any one of the preceding claims, characterized in that Before applying the binder on the polymer composite sheet layer, the back side of the polymer composite sheet layer is pre-treated using chemical etching and / or plasma etching.

10. Rolling bearing (10) according to any one of the preceding claims, characterized in that The friction coefficient of the polymer composite sheet layer (6) in dry contact with the aluminum alloy is between 0.05 and 0.

4.

11. Rolling bearing (10) according to any one of the preceding claims, characterized in that The polymer composite sheet layer (6) has a dielectric strength greater than 15 kV / mm and a dielectric constant lower than 4.

12. A method for producing a rolling bearing (10) according to any one of the preceding claims, wherein: The rolling bearing (10) comprises at least one outer ring (1), at least one inner ring (2) and at least one rolling element (3) arranged between the at least one outer ring (1) and the at least one inner ring (2), wherein the outer surface of the at least one outer ring (1) is configured to be fitted into a first element, the inner surface of the inner ring (2) is configured to be fitted into a second element, and the first element and the second element are rotatable relative to each other, wherein the method comprises the following steps: Providing a polymer composite sheet layer (6), wherein the polymer composite sheet layer comprises at least one perfluoroalkyl and / or polyfluoroalkyl component, and applying a bonding agent to at least one of the outer surface of the outer ring (1) and the inner surface of the inner ring (2) and / or the polymer composite sheet layer (6), The polymer composite sheet layer (6) is bonded to at least one of the outer surface of the outer ring (1) and the inner surface of the inner ring (2).

13. The method for manufacturing a rolling bearing according to claim 12, characterized in that The method further comprises, before applying the polymer composite sheet layer (6), pre-treating the back side of the polymer composite sheet layer using chemical etching and / or plasma etching.

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