JP2007177800A - Bearing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To increase working efficiency by a simple mounting method and provide highly reliable fitting by preventing creeping. <P>SOLUTION: A chamfered part 21 is circumferentially continuously formed at the end of an inner ring 2. The dimension of the chamfered part 21 is different from a circumferential position to a circumferential position. A spacer 5 fitted to the end of the inner ring 2 adjacent to each other has a projecting part 51 circumferentially engaged with the chamfered part 21. The dimension of the projecting part 51 is different from a circumferential position to a circumferential position correspondingly to a difference in the dimensions of the chamfered part 21. The dimension of the chamfered part of the inner ring 2 is formed by circumferentially continuously connecting the two types of large and small dimensions. A large chamfered part 21a and a small chamfered part 21b are disposed symmetric with respect to 180°. Since the projecting part 51 of the spacer 5 secured to the shaft S facing the chamfered parts 21a, 21b is engaged with the chamfered parts 21a, 21b, the projecting part 51 of the spacer 5 acts as a wedge even in clearance fit. As a result, the creep of the inner ring 2 can be surely prevented. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention achieves highly reliable fitting by improving work efficiency and preventing creep in fitting of annular members (inner ring or outer ring) having different linear expansion coefficients by a simple mounting method. It is related with the bearing apparatus which can do.

  In a fitting portion between a shaft that is a rotating body and an inner ring that is externally fitted to the shaft, the linear expansion coefficients may be different from each other. For example, an inner ring made of ceramics or an inner ring whose inner surface is coated with ceramics for bearing steel such as SUJ2 is externally fitted to a shaft made of a steel material such as carbon steel.

  In this case, ceramics has a smaller coefficient of linear expansion and a larger modulus of longitudinal elasticity than metal.

  Therefore, if the clearance between the metal shaft and the ceramics internal transportation is zero at normal temperature, the inner ring remains almost undeformed at the operating temperature compared to the shaft. Therefore, a negative gap is formed between the shaft and the inner ring, and tensile stress acts on the inner ring.

As a result, as known in Patent Document 1, ceramics have a risk of breaking the inner ring when the tensile stress in the circumferential direction exceeds 196 N / mm ² (20 kgf / m ² ). For this reason, it is considered undesirable to have a negative gap in this way.

  For this reason, a positive gap is provided between the shaft and the inner ring at room temperature so that a negative gap does not occur at the operating temperature. However, if there is a positive gap, creep occurs between the shaft and the inner ring, which is not preferable.

  From such a viewpoint, Patent Document 2 and Patent Document 3 have a structure in which both end surfaces of the inner ring are supported by spacers having tapered surfaces to absorb a difference in expansion between materials having different linear expansion coefficients.

  FIG. 4 is a cross-sectional view of a state where a conventional cylindrical roller bearing according to Patent Document 2 is mounted on a shaft. It is the prior art example applied to the assembly | attachment of the inner ring | wheel (annular body) of a cylindrical roller bearing, and an axis | shaft (counter member). The cylindrical roller bearing shown in FIG. 1 is composed of a rolling element 3 of cylindrical rollers arranged between an outer ring 1, an inner ring 2, and both wheels 1 and 2 and guided by a cage 4. In this conventional example, the inner ring 2 is fitted to the shaft S by a clearance fit, and both end portions in the axial direction of the inner ring 2 are respectively connected by a pair of second spacers 20 via a pair of spacers 10. It is positioned in the axial direction and supported in the radial direction. The spacer 10 includes a cylindrical portion 11 that fits on both sides in the axial direction of the inner ring 2 and a tapered surface 12 that opens outward with respect to the axial direction of the inner ring 2.

FIG. 5 is a cross-sectional view of a state where a conventional cylindrical roller bearing according to Patent Document 3 is mounted on a shaft. An outer ring 1 that is an outer race and an inner ring 2 that is an inner race are respectively attached to a bearing box H and a shaft S that are mating members of a cylindrical roller bearing. Cylindrical roller rolling elements 3 are arranged to be freely rollable. The inner ring 2 of the cylindrical roller bearing is formed of a material whose linear expansion coefficient is smaller than the linear expansion coefficient of the shaft S, and the axially opposite end faces 2a and 2a of the inner ring 2 are orthogonal to the axial center line of the bearing. An inclined surface having angles θ _1i and θ _2i inclined in the outward opening direction with respect to the bearing center line _OO is formed, and is fitted to the shaft S by a clearance fit having a clearance. Both side end faces 2a, 2a of the inner ring 2 are attached by opposing end faces of the spacers 10, 10 fitted with an interference fit with respect to the axis S. The spacers 10 and 10 are formed of a material having a linear expansion coefficient substantially equal to the linear expansion coefficient of the shaft S.

FIG. 6 is a cross-sectional view of a conventional ball bearing according to Patent Document 4 mounted on a shaft. A total ceramic ball bearing in which a ball rolling element 3 interposed between the outer ring 1, the inner ring 2, and both the wheels 1 and 2 is formed of a ceramic material is formed on the small diameter portion Sa of the metal hollow shaft S. It is fitted and fixed by press-fitting. In the fitting portion of the shaft S with the inner ring 2, a plurality of long holes 30 penetrating in the radial direction and having an axial length B2 larger than the inner ring width B1 are formed on the circumference. The inner peripheral surface of the inner ring 2 is located on the long hole 30. Further, the inner ring 2 is fixed on the shaft S so that both end faces 2b and 2c are held by spacers 10 and 10 fixed to the shaft S and cannot move in the axial direction. Reference numeral 4 denotes a cage that holds the ball rolling elements 3 at equal intervals on the circumference, and is formed of, for example, a heat-resistant synthetic resin.
JP 63-1111118 A Japanese Patent Laid-Open No. 05-071548 Japanese Patent No. 2586503 JP 2000-220651 A

  However, in the structures of Patent Documents 2 and 3, the inner ring of the bearing is supported so as to be sandwiched between spacers having tapered surfaces at both ends, and both inner diameters of the inner ring are not in contact with the shaft. Since the radial load is received by this tapered surface, the load applied to the center of the inner ring through the rolling element deflects the inner ring having a double-end support beam structure, and at the same time, an axial tensile stress is generated on the inner diameter surface of the inner ring.

  Therefore, it is suitable for applications in a special atmosphere where light loads and high-speed rotation or the like are disliked, but caution is required at sites where excessive radial loads are applied.

  Moreover, in patent document 4, the elongate hole is provided in the bearing fitting part of a hollow shaft, and it is making a flexible structure, and the interference increase by an expansion difference is absorbed. However, there is a restriction that it is a hollow shaft, and since it is a flexible structure, its application is restricted.

  The present invention has been made in view of the circumstances as described above, and in the fitting of annular members (inner rings or outer rings) having different linear expansion coefficients, the working efficiency is improved by a simple attachment method, and creep is performed. It is an object of the present invention to provide a bearing device that can realize a highly reliable fitting by preventing.

In order to achieve the above object, a bearing device according to the present invention includes an inner ring made of ceramics, or a rolling bearing having an inner ring with a ceramic coating applied to the inner diameter surface thereof fitted to the outer diameter surface of the shaft. In the bearing device,
At the end of the inner ring, a chamfered portion is continuously formed on the circumference, and the dimensions of the chamfered portion are different on the circumference,
The spacer mounted adjacent to the end of the inner ring has a convex portion that engages with the chamfered portion on the circumference,
The dimensions of the convex portions are different on the circumference corresponding to the differences in the dimensions of the chamfered portions.

Further, in a bearing device in which a rolling bearing provided with an outer ring made of ceramics or an outer ring having a ceramic coating on the outer diameter surface is fitted to the inner diameter surface of the housing,
At the end of the outer ring, a chamfered portion is continuously formed on the circumference, and the dimensions of the chamfered portion are different on the circumference,
The spacer mounted adjacent to the end of the outer ring has a convex portion that engages with the chamfered portion on the circumference,
The dimensions of the convex portions are different on the circumference corresponding to the differences in the dimensions of the chamfered portions.

Preferably, the linear expansion coefficient of the material of the shaft is smaller than the linear expansion coefficient of ceramics of the material of the inner ring, or ceramics coated on the inner diameter surface of the inner ring, or
The linear expansion coefficient of the material of the housing is smaller than the linear expansion coefficient of ceramics of the outer ring material or ceramics coated on the outer diameter surface of the outer ring.

Preferably, the fitting between the shaft and the inner ring is a gap fit, or the fitting between the housing and the outer ring is a gap fit.

Further preferably, one of the inner ring or the outer ring is made of ceramics or coated with ceramics, and the one ring is a rotating ring,
The other race ring is made of bearing steel that is not coated with ceramics.

  Further preferably, the spacer is made of a material having a linear expansion coefficient equivalent to that of the shaft or the housing, and is fitted to the shaft or the housing with an interference fit.

  Further preferably, the spacer is made of a material having a linear expansion coefficient equivalent to the material of the shaft or the housing, and is fixed to the shaft or the housing with a fixing jig.

  According to the present invention, in the fitting of annular members having different linear expansion coefficients, it is possible to realize a highly reliable fitting by improving work efficiency by a simple attachment method and preventing creep.

  Hereinafter, a bearing device according to an embodiment of the present invention will be described with reference to the drawings.

  First, the present invention will be outlined. Conventionally, fitting of annular members having different linear expansion coefficients, for example, inner rings obtained by coating ceramics on bearing steel such as SUJ2 on the inner diameter surface to be fitted with ceramics or shafts, carbon steel, etc. When fitting to a steel shaft, it should be assembled with a clearance fit during assembly in consideration of the difference in expansion due to temperature during operation. In this case, since it is a clearance fit, the shrink-fitting operation is unnecessary and the workability is improved. However, in the case immediately after the start of operation when the temperature of the bearing does not reach a steady state, since it is a clearance fit, relative slippage, that is, creep occurs between the inner ring inner diameter surface and the shaft outer diameter surface.

  For this reason, in the present invention, steel that is fixed to a shaft having a convex portion (claw) that meshes with the chamfered portion of the inner ring that does not normally change in the circumferential direction for preventing creep. When the inner ring creeps, the convex part (claw) of the inner ring and the inner ring chamfered part are arranged so that the convex part (claw) of the spacer is engaged with the chamfered part of the inner ring. By the interference, creep of the inner ring is suppressed.

  As described in claim 6, the spacer is fitted to the shaft with an interference fit, and even if the temperature changes by selecting the same or close to the shaft's secondary expansion coefficient, the fit changes. It can be fixed to the shaft.

  Further, the spacer can be fixed to the shaft with a fixing jig such as a knock pin, a notch, or a key.

  Note that the shape of the chamfered portion may be any shape as long as it changes on the circumference, but in order to prevent destruction due to stress concentration of ceramics, discontinuous changes on the circumference, for example, notches and corner R dimensions An extremely small slot is not appropriate because stress concentrates on the corner R portion when it interferes with the opposing spacer. Therefore, the dimension of the chamfered portion is suitably changed continuously on the circumference that can be easily processed by a lathe. For example, as will be described later, it is appropriate to change the dimensions of the two chamfered portions of large and small into an elliptical shape.

  The shape of the convex part (claw) of the spacer fitted to this chamfered part is also preferably the same shape as the dimension of the chamfered part, but it is not always necessary to make contact with no gap, and there is no gap between the chamfered surface and the claw. It may be open.

  The present invention is not limited to the case where the shaft and the inner ring are fitted, but the outer ring is made of ceramics or the outer ring formed by coating ceramics on the bearing steel such as SUJ2 on the outer diameter surface fitting with the housing. The present invention can also be applied when fitted to a steel or cast iron housing.

  In addition, the difference in the amount of expansion due to the temperature during operation is larger on the rotating side raceway than on the stationary side raceway, so it is more effective to apply it to the rotating raceway side.

  FIG. 1A is a longitudinal sectional view of a state in which a bearing device according to an embodiment of the present invention is fitted to a shaft, and FIGS. 1B and 1C are circled in FIG. It is an expanded sectional view of a part, (b) shows a large chamfering part, (c) shows a small chamfering part.

  FIG. 2 is a cross-sectional view of the bearing device according to the embodiment of the present invention shown in FIG.

  The cylindrical roller bearing is constituted by a rolling element 3 of a cylindrical roller that is arranged between the outer ring 1, the inner ring 2, and both the wheels 1 and 2 and is guided by a cage 4.

  As shown in FIGS. 1B, 1C, and 2, a chamfered portion 21 is continuously formed on the end of the inner ring 2, and the dimensions of the chamfered portion 21 are different in the circumferential direction. is there.

  The spacer 5 mounted adjacent to the end of the inner ring 2 has a convex portion 51 that engages with the chamfered portion 21 on the circumference, and the dimension of the convex portion 51 corresponds to the difference in the dimension of the chamfered portion 21. It is different on the circumference. The convex part 51 is a nail, for example.

  The dimension of the chamfered portion of the inner ring 2 is obtained by continuously connecting two types of large and small dimensions on the circumference, and is 180 degrees symmetrical, and the large chamfered portion 21a and the small chamfered portion 21b are arranged. When viewed from the axial section, both the chamfered portions 21a and 21b appear to be elliptical as shown in FIG.

  In addition, the spacer 5 is fitted to the shaft S with an interference fit, and even when the temperature changes by selecting the same as or close to the linear expansion coefficient of the shaft S, the fit does not change. Can be fixed. In addition, although the shape of the convex part 51 (claw) of the spacer 5 fitted to the chamfered parts 21a and 21b is desirably the same shape as the dimensions of the chamfered parts 21a and 21b, it is not always necessary to make contact with no gap, and the chamfered surface. There may be a gap between the nail.

  In this way, the convex portion 51 (claw) of the spacer 5 fixed to the shaft S facing the chamfered portions 21a and 21b meshes, so that the convex portion 51 (claw) of the spacer 5 is wedged even in clearance fit. Thus, creep of the inner ring 2 can be reliably prevented.

  According to the present embodiment, in the fitting of annular members having different linear expansion coefficients, it is possible to realize a highly reliable fitting by improving work efficiency by a simple attachment method and preventing creep. it can.

  In the embodiment, the shaft S and the spacer 5 are separated from each other, but the left spacer in FIG. 1 may be formed integrally with the fitting portion with the bearing end surface of the shaft S. This can be similarly applied to the housing and the outer ring.

  FIG. 3 is a longitudinal sectional view of a state in which a bearing device according to a modification of the embodiment of the present invention is fitted to a shaft.

  In this modification, as shown in a circled portion in FIG. 3, the spacer 5 is fixed to the shaft S by a fixing jig 6 such as a knock pin, a notch, or a key.

  Other configurations, operations, and effects are the same as those in the above-described embodiment.

  In addition, this invention is not limited to embodiment mentioned above, A various deformation | transformation is possible. For example, the present invention is not limited to the case where the shaft and the inner ring are fitted, but the outer ring is made of ceramics or the outer ring in which ceramic is coated on the outer diameter surface to be fitted with the housing. It can also be applied to the case of fitting to.

(A) is a longitudinal cross-sectional view of a state in which the bearing device according to the embodiment of the present invention is fitted to the shaft, and (b) and (c) are the parts circled in (a), respectively. (B) shows a large chamfered part, (c) shows a small chamfered part. It is a cross-sectional view of the bearing device according to the embodiment of the present invention shown in FIG. It is a longitudinal cross-sectional view of the state which fitted the bearing apparatus which concerns on the modification of embodiment of this invention to the axis | shaft. It is sectional drawing of the state which mounted | wore the shaft with the cylindrical roller bearing of the prior art example which concerns on patent document 2. FIG. It is sectional drawing of the state which mounted | wore the shaft with the cylindrical roller bearing of the prior art example which concerns on patent document 3. It is sectional drawing of the state which mounted | wore the shaft with the ball bearing of the prior art example which concerns on patent document 4.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Outer ring 2 Inner ring 21 Chamfered part 21a Large chamfered part 21b Small chamfered part 3 Rolling element of cylindrical roller 4 Cage 5 Spacer 51 Convex part (claw)
6 Fixing jig

Claims (7)

In a bearing device in which a rolling bearing having an inner ring made of ceramics or an inner ring with a ceramic coating on the inner diameter surface is fitted to the outer diameter surface of the shaft,
At the end of the inner ring, a chamfered portion is continuously formed on the circumference, and the dimensions of the chamfered portion are different on the circumference,
The spacer mounted adjacent to the end of the inner ring has a convex portion that engages with the chamfered portion on the circumference,
The bearing device is characterized in that the dimensions of the convex portions are different on the circumference corresponding to the differences in the dimensions of the chamfered portions. In a bearing device in which a rolling bearing provided with an outer ring made of ceramics or an outer ring with a ceramic coating on the outer diameter surface is fitted to the inner diameter surface of the housing,
At the end of the outer ring, a chamfered portion is continuously formed on the circumference, and the dimensions of the chamfered portion are different on the circumference,
The spacer mounted adjacent to the end of the outer ring has a convex portion that engages with the chamfered portion on the circumference,
The bearing device is characterized in that the dimensions of the convex portions are different on the circumference corresponding to the differences in the dimensions of the chamfered portions. The linear expansion coefficient of the material of the shaft is smaller than the linear expansion coefficient of ceramics of the material of the inner ring, or ceramics coated on the inner diameter surface of the inner ring, or
3. The bearing device according to claim 1, wherein a linear expansion coefficient of a material of the housing is smaller than a linear expansion coefficient of ceramics of the material of the outer ring or ceramics coated on an outer diameter surface of the outer ring. The fitting between the shaft and the inner ring is a gap fit, or the fitting between the housing and the outer ring is a gap fit. Bearing device. One of the inner ring or the outer ring is made of ceramics or coated with ceramics, and the one of the ring is a rotating wheel,
The bearing device according to any one of claims 1 to 4, wherein the other bearing ring is made of bearing steel that is not coated with ceramics.   6. The spacer according to claim 1, wherein the spacer is made of a material having a linear expansion coefficient equivalent to that of the shaft or the housing, and is fitted to the shaft or the housing with an interference fit. 2. A bearing device according to item 1.   6. The spacer according to claim 1, wherein the spacer is made of a material having a linear expansion coefficient equivalent to that of the shaft or the housing, and is fixed to the shaft or the housing with a fixing jig. The bearing device according to item.

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