Electric corrosion prevention rolling bearing

Abstract

To provide an electric corrosion prevention rolling bearing which can preferably inhibit a gap between an inner / outer ring and an insulation coating from occurring due to contraction during insert molding and secure good electric corrosion prevention effect.SOLUTION: In a structure of an electric corrosion prevention rolling bearing according to the invention, at an electric corrosion prevention rolling bearing (a bearing 100) in which an insulation coating formed of a resin is formed on a surface of an inner ring or an outer ring by insert molding, a groove 150 is formed on an inner peripheral surface 112 of the inner ring 110 or an outer peripheral surface 122 of the outer ring 120 by laser processing. The groove 150 inclines relative to the inner peripheral surface 112 of the inner ring 110 or the outer peripheral surface 122 of the outer ring 120 in a depth direction.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a rolling bearing that is effective in preventing electrolytic corrosion. [Background technology]

[0002] In recent years, with the advancement of development of electric cars (EVs) and hybrid cars (HVs), the number of high-voltage components installed in each automobile is increasing. When current from these high-voltage components flows through a bearing, electrolytic corrosion occurs on the surfaces of the rolling elements of the bearing and on the raceway surfaces of the outer and inner rings, causing damage. Patent Document 1, for example, discloses a rolling bearing that is resistant to electrolytic corrosion and has an insulating coating on the surface of the raceway rings. In Patent Document 1, the insulating coating is formed from a polyphenylene sulfide resin containing glass fiber and a non-fibrous insulating inorganic filler.

[0003] In the rolling bearing of Patent Document 1, multiple circumferential grooves are formed on the surfaces of the inner and outer rings, and an insulating coating is then applied over these. As a result, the ridges formed on the insulating coating during injection molding fit into the circumferential grooves. This prevents "axial displacement" of the coating, and is said to prevent peeling or lifting during operation. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 3068311 Summary of the Invention [Problem to be solved by the invention]

[0005] Insert molding, as exemplified in Patent Document 1, is a commonly used method for forming an insulating coating on the inner or outer ring. However, when forming an insulating coating by insert molding, the insulating coating shrinks more significantly during cooling due to the difference in thermal expansion coefficients between the inner or outer ring and the insulating coating. This creates a gap between the inner or outer ring and the insulating coating. This results in the actual interference being smaller than the desired interference, making creep more likely to occur. This can result in wear of the insulating coating, which can ultimately lead to a deterioration in insulation performance.

[0006] One method of suppressing the occurrence of gaps between the inner or outer ring and the insulating coating during cooling is to form a circumferential groove on the surface of the inner or outer ring, as described in Patent Document 1. However, Patent Document 1 takes into account the "axial load" during operation and does not consider the radial force that occurs immediately after insert molding. With circumferential grooves formed by machining, as in Patent Document 1, the peeling direction is the same as the groove depth direction, so the resin ribs formed within the groove tend to come out of the groove, resulting in poor adhesion to the insulating coating. As a result, while the ribs formed on the insulating coating are effective in preventing axial misalignment, they tend to come out of the circumferential groove when shrinkage occurs during cooling, and are therefore not sufficiently effective in suppressing the occurrence of gaps between the inner or outer ring and the insulating coating.

[0007] In view of these problems, the present invention has an object to provide an electrolytic corrosion-resistant rolling bearing that can effectively prevent the occurrence of gaps between the inner ring or outer ring and the insulating coating due to shrinkage during insert molding, and that can ensure good electrolytic corrosion prevention effects. [Means for solving the problem]

[0008] In order to solve the above problems, a typical configuration of an electrolytic corrosion-resistant rolling bearing according to the present invention is an electrolytic corrosion-resistant rolling bearing in which an insulating resin coating is formed on the surface of the inner ring or outer ring by insert molding, and in which grooves are formed by laser processing on the inner surface of the inner ring or the outer surface of the outer ring, the grooves being formed in a grid pattern on the inner surface of the inner ring or the outer surface of the outer ring, and including circumferential grooves extending in the circumferential direction on both sides of the centre of the bearing, with the circumferential grooves sloping towards the centre in the depth direction.

[0009] The grooves may be formed in a grid pattern on the inner peripheral surface of the inner ring or the outer peripheral surface of the outer ring.

[0010] The grooves may include circumferential grooves extending circumferentially on both sides of the center of the bearing on the inner peripheral surface of the inner ring or the outer peripheral surface of the outer ring, and the circumferential grooves may be inclined toward the center in the depth direction.

[0011] The grooves may be formed in a crisscross pattern on the inner peripheral surface of the inner ring or the outer peripheral surface of the outer ring. [Effects of the Invention]

[0012] The present invention can provide an electrolytic corrosion prevention rolling bearing that can effectively prevent the occurrence of gaps between the inner ring or outer ring and the insulating coating due to shrinkage during insert molding, and can ensure good electrolytic corrosion prevention effects. [Brief explanation of the drawings]

[0013] [Figure 1] 1 is a diagram illustrating an electrolytic corrosion prevention rolling bearing according to an embodiment of the present invention. [Figure 2] FIG. 2 is a partial enlarged view of the outer peripheral surface of the outer ring of FIG. 1. [Figure 3] FIG. [Figure 4] FIG. [Figure 5] 2 is a diagram illustrating the results of CAE analysis of the bearing of the present embodiment shown in FIG. 1. FIG. [Figure 6] FIG. 10 is a diagram illustrating the relationship between the laser processing depth and the gap occurrence rate. [Figure 7] 10A and 10B are diagrams illustrating inner diameter measurements of the bearing of the present embodiment and a conventional bearing as a comparative example. [Figure 8] 1 is a diagram illustrating a conventional rolling bearing having electrolytic corrosion prevention properties. DETAILED DESCRIPTION OF THE INVENTION

[0014] Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings. The dimensions, shapes, materials, and other specific values shown in the embodiments are merely examples for facilitating understanding of the invention and do not limit the present invention unless otherwise specified. In this specification and drawings, elements having substantially the same functions and configurations are designated by the same reference numerals to avoid redundant explanation, and elements not directly related to the present invention will not be shown or described.

[0015] 1 is a diagram illustrating an electrolytic corrosion-resistant rolling bearing according to this embodiment (hereinafter simply referred to as bearing 100), showing a cross section of bearing 100. As shown in FIG. 1, this embodiment illustrates a single-row deep groove ball bearing as bearing 100, which has a row of balls as rolling elements 130 between an inner ring 110 and an outer ring 120.

[0016] The surface of inner ring 110 is made up of an inner circumferential surface 112 and side surfaces 114 on either side thereof, while the surface of outer ring 120 is made up of an outer circumferential surface 122 and side surfaces 124 on either side thereof. A resin insulating coating 140 is formed by insert molding on the surfaces of inner ring 110 and outer ring 120. Side surface grooves 116, 126 are formed in side surface 114 of inner ring 110 and side surface 124 of outer ring 120, and insulating coating 140 is engaged with side surface 114 of inner ring 110 and side surface 124 of outer ring 120 in these side surface grooves 116, 126.

[0017] Although the present embodiment illustrates a configuration in which the insulating coating 140 is formed on the surfaces of both the inner ring 110 and the outer ring 120, the present invention is not limited to this. The present invention can also be applied to a configuration in which the insulating coating 140 is formed on only one of the inner ring 110 or the outer ring 120.

[0018] Fig. 2 is a partially enlarged view of the outer peripheral surface 122 of the outer ring 120 in Fig. 1. As shown in Fig. 1 and Fig. 2, this embodiment is characterized in that grooves 150 formed by laser processing are provided on the inner peripheral surface 112 of the inner ring 110 and the outer peripheral surface 122 of the outer ring 120 (Fig. 2 illustrates the outer peripheral surface 122). The grooves 150 are inclined in the depth direction with respect to the inner peripheral surface 112 of the inner ring 110 and the outer peripheral surface 122 of the outer ring 120.

[0019] In particular, grooves 150 of bearing 100 of this embodiment are inclined toward the center C (see FIG. 1) in the axial direction of bearing 100. For this reason, in the cross section of bearing 100 as shown in FIG. 1, grooves 150 are "shaped like an inverted V that is symmetrical about center C," and insulating coating 140 that has penetrated into grooves 150 to fill them also has a "shaped like an inverted V that is symmetrical about center C" that is a copy of the shape of groove 150.

[0020] According to the above configuration, when a force is applied to insulating coating 140 in a direction that causes it to peel off from inner circumferential surface 112 or outer circumferential surface 122, insulating coating 140 remains engaged in groove 150. This makes it possible to effectively prevent insulating coating 140 from coming off groove 150, improving adhesion between insulating coating 140 and groove 150. This makes it possible to effectively prevent gaps from occurring between insulating coating 140 and inner ring 110 or outer ring 120, which are caused by shrinkage during insert molding, and ensures good electrolytic corrosion prevention.

[0021] In the laser processing used to form groove 150 in this embodiment, the groove width can be intentionally changed by varying the laser output. Therefore, by increasing the laser output when forming groove 150, it is possible to melt and vaporize a larger portion of the deeper portions of inner circumferential surface 112 and outer circumferential surface 122, and as shown in FIG. 2, the width W2 of groove 150 at the deeper positions can be made wider than the width W1 of groove 150 at the shallower positions.

[0022] With this configuration, the insulating coating 140 formed to fill the groove 150 has the shape of the groove 150 transferred to it, with the deeper portions of the groove 150 being wider than the shallower portions. As a result, the insulating coating 140 that has entered the groove 150 functions as a wedge (anchor effect), making it difficult for the insulating coating 140 to peel off from the groove 150. This further improves the adhesion between the insulating coating 140 and the groove 150.

[0023] 3 and 4 are external perspective views of bearing 100. Note that in order to explain the shape of groove 150, insulating coating 140 is not shown in Fig. 3 and 4. Furthermore, components that are common to bearing 100 are given the same reference numerals and descriptions thereof will be omitted.

[0024] 3, grooves 150 are formed in a grid pattern (vertical and horizontal) on the inner peripheral surface 112 of the inner ring 110 and the outer peripheral surface 122 of the outer ring 120. That is, grooves 150 are made up of a plurality of circumferential grooves 152 extending in the circumferential direction on both sides of the center of bearing 100a, and a plurality of axial grooves 154 extending in the axial direction and intersecting with circumferential grooves 152.

[0025] As shown in FIG. 3, a grid-like groove consisting of circumferential grooves 152 and axial grooves 154 is formed on inner surface 112 of inner ring 110 and outer surface 122 of outer ring 120, thereby increasing the contact area between insulating coating 140 and the inner surface of groove 150 and further improving adhesion therebetween.

[0026] 3, circumferential groove 152 (corresponding to groove 150 shown in FIG. 1) is inclined toward the center of bearing 100a in the depth direction, so that insulating coating 140 is locked into groove 150. Therefore, the above-mentioned effects can be obtained.

[0027] In the bearing 100b shown in Fig. 4, grooves 150 are formed in a knurled pattern on the inner peripheral surface 112 of the inner ring 110 and the outer peripheral surface 122 of the outer ring 120. In detail, grooves 150 are composed of a plurality of first inclined grooves 156 inclined by θ1 with respect to the axial direction, and a plurality of second inclined grooves 158 inclined by θ2 with respect to the axial direction and intersecting with the first inclined grooves 156. Even with this configuration, the contact area between the insulating coating 140 and the inner surface of groove 150 increases, thereby achieving the same effect as the bearing 100a in Fig. 3.

[0028] When the groove 150 is formed in a crisscross pattern, the first inclined groove 156 and the second inclined groove 158 do not have to be inclined in the depth direction, or the first inclined groove 156 and the second inclined groove 158 may be inclined in the same direction relative to the circumferential direction, or may be inclined in different directions relative to the circumferential direction.

[0029] Fig. 5 is a diagram illustrating the results of a CAE analysis of the bearing of the present embodiment shown in Fig. 1. In the graph shown in Fig. 5(a), the horizontal axis represents the inclination angle θ of the groove 150 as shown in Fig. 5(b). The vertical axis represents the gap between the inner circumferential surface 112 of the inner ring 110 and the insulating coating 140 (see gap G in Fig. 8).

[0030] 5, the gap becomes smaller as the inclination angle θ of groove 150 becomes smaller. When the angle θ of groove 150 is 15°, the gap is approximately 0.08 mm, and thereafter, even if the angle θ of groove 150 becomes larger, the amount of the gap hardly changes. Therefore, it can be seen that by setting the inclination angle of groove 150 to 15 degrees or more, the effect of reducing the gap between inner circumferential surface 112 of inner ring 110 and insulating coating 140 can be reliably obtained.

[0031] Fig. 6 is a diagram illustrating the relationship between the laser processing depth and the gap occurrence rate. Fig. 6 illustrates the laser processing depth as the groove depth d (see Fig. 2), and shows the change in the gap occurrence rate between the insulating coating 140 and the groove 150 when the laser processing depth is changed.

[0032] 6, when the laser processing depth is 0 μm, i.e., when no laser processing is performed, the gap occurrence rate is 100%, and as the laser processing depth increases, the gap occurrence rate decreases. When the laser processing depth exceeds approximately 20 μm, the gap occurrence rate becomes 0%. From this, it can be seen that if the laser processing depth, i.e., the depth of the groove 150, is 20 μm or more, the occurrence of gaps between the insulating coating 140 and the groove 150 can be effectively prevented.

[0033] Fig. 7 is a diagram illustrating inner diameter measurements for the bearing 100 of this embodiment and a conventional bearing 10, which is a comparative example. Fig. 8 is a diagram illustrating a conventional rolling bearing that is resistant to electrolytic corrosion (hereinafter referred to as bearing 10). Note that components that are common to the bearing 100 of this embodiment and the conventional bearing 10 are given the same reference numerals.

[0034] Fig. 7(a) is a diagram illustrating an example of the arrangement when measuring the inner diameter of the inner ring 110 of the bearing 100 of this embodiment, which is an example. Fig. 7(b) is a diagram illustrating an example of the arrangement when measuring the inner ring 12 of a conventional bearing 10, which is a comparative example. In the bearing 100 of this embodiment illustrated in Fig. 7(a), the insulating coating 140 and the inner ring 110 are in close contact with each other.

[0035] In conventional bearing 10, as illustrated in Figure 8, inner circumferential surface 13 of inner ring 12 and outer circumferential surface 15 of outer ring 14 are flat and do not have grooves 150 formed thereon. If insulating coating 140 is formed on the surfaces of inner ring 12 and outer ring 14 of such conventional bearing 10 by insert molding, insulating coating 140 will peel off from inner circumferential surface 13 of inner ring 12 and outer circumferential surface 15 of outer ring 14 due to shrinkage during mold release. For this reason, in conventional bearing 10, a gap G is generated between insulating coating 140 and inner ring 12, as illustrated in Figures 7(b) and 8.

[0036] When measuring the inner diameter of the inner ring using inner diameter measuring instrument 200, movable terminal 210 and fixed terminal 220 are placed between inner ring 110 of this embodiment and conventional inner ring 12, as shown in Fig. 7(a) . When a load is applied to movable terminal 210, movable terminal 210 moves toward fixed terminal 220.

[0037] 7(c) is a diagram illustrating the relationship between the radial load and the amount of change in the inner diameter of the inner ring. As shown in Fig. 7(c), in the comparative example (inner ring 12 of conventional bearing 10), the amount of movement of movable terminal 210 increases significantly as the load (radial load) applied from movable terminal 210 increases.

[0038] On the other hand, in the example (inner ring 110 of bearing 100 of this embodiment), the amount of movement of movable terminal 210 gradually increases as the load (radial load) applied from movable terminal 210 increases, but when the radial load is at a predetermined value L, the amount of movement of movable terminal 210 is about 1 / 4 of the amount of movement of comparative example. From this, it can be seen that the shape of the insulating coating of the comparative example is unstable and the desired shape is not obtained. And, according to bearing 100 of this embodiment, it can be seen that insulating coating 140 has a shape that follows the shape of inner peripheral surface 112 of inner ring 110 and can maintain a stable shape when a load is applied.

[0039] While the preferred embodiments of the present invention have been described above with reference to the accompanying drawings, it goes without saying that the present invention is not limited to such examples. It is clear that those skilled in the art can conceive of various modifications and alterations within the scope of the claims, and it is understood that such modifications and alterations naturally fall within the technical scope of the present invention. [Industrial Applicability]

[0040] The present invention can be used as an electrolytic corrosion prevention rolling bearing that is effective in preventing electrolytic corrosion. [Explanation of symbols]

[0041] 10...bearing, 12...inner ring, 13...inner peripheral surface, 14...outer ring, 15...outer peripheral surface, 100...bearing, 100a...bearing, 100b...bearing, 110...inner ring, 112...inner peripheral surface, 114...side surface, 116...side surface groove, 120...outer ring, 122...outer peripheral surface, 124...side surface, 126...side surface groove, 130...rolling element, 140...insulating coating, 150...groove, 152...circumferential groove, 154...axial groove, 156...first inclined groove, 158...second inclined groove, 210...movable terminal, 220...fixed terminal, G...gap

Claims

[Claim 1] In an electrolytic corrosion prevention rolling bearing in which a resin insulating coating is formed on the surface of the inner ring or outer ring by insert molding, a groove is formed by laser processing on the inner peripheral surface of the inner ring or the outer peripheral surface of the outer ring, The groove is a lattice pattern is formed on the inner peripheral surface of the inner ring or the outer peripheral surface of the outer ring, a circumferential groove extending circumferentially on either side of the center of the bearing; An electrolytic corrosion prevention rolling bearing, characterized in that the circumferential groove is inclined toward the center in the depth direction.

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