JP2011021677A - Attaching structure for rolling bearing - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide attaching structure for a rolling bearing with an outer ring hardly creeping with respect to a housing, and capable of reducing manhours and a manufacturing cost. <P>SOLUTION: An outer circumferential face of the second member 21 of an outer ring 10 of a ball bearing 1 is internally fit and fixed, by press fitting, on an inner circumferential face of the aluminum housing 1. The second member 21 is prepared by a powder metallugical method using aluminum powder and iron powder. An inner circumferential side of the second member 21 is constituted of iron, and an outer circumferential side of the second member 21 is constituted of aluminum. An area of an intermediate part of the second member 21 is constituted of an alloy of aluminum and iron. The area of the intermediate part is formed to increase monotonously an aluminum weight composition ratio as going radially outside. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a rolling bearing mounting structure, for example, a rolling bearing mounting structure suitable for use in an engine accessory such as an alternator mounted on an automobile.

  Conventionally, as a mounting structure of a rolling bearing, there is one described in JP 2003-287043 A (Patent Document 1).

  This mounting structure of the rolling bearing forms a part of an alternator of an automobile whose operating temperature range is high. The rolling bearing mounting structure includes an aluminum alloy housing and a ball bearing, and the ball bearing includes an outer ring, an inner ring, and a plurality of balls. The outer ring of the ball bearing has an annular groove on the outer peripheral surface of the outer ring. In the annular groove, a creep preventing member is disposed without a gap by injection molding. The creep preventing member is made of a synthetic resin material having a linear expansion coefficient larger than that of an aluminum alloy. The outer ring of the ball bearing is fitted and fixed to the inner peripheral surface of the housing by press fitting.

  In this rolling bearing mounting structure, an anti-creep member made of a synthetic resin material having a linear expansion coefficient larger than that of an aluminum alloy is disposed in an annular groove formed on the outer peripheral surface of the outer ring. A tightening margin is secured between the housing and the outer ring to prevent creeping with respect to the housing.

Japanese Patent Laying-Open No. 2003-287043 (FIG. 1)

  The conventional rolling bearing mounting structure has the advantage that creep of the outer ring with respect to the housing can be suppressed. On the other hand, it is indispensable to process the portion where the resin enters the outer ring of the ball bearing, which requires a large number of man-hours and manufacturing costs. There is a problem.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a rolling bearing mounting structure in which an outer ring is less likely to creep with respect to a housing, and man-hours and manufacturing costs are small.

In order to solve the above problems, the rolling bearing mounting structure of the present invention is
An annular housing made of aluminum or aluminum alloy;
A rolling bearing comprising an inner ring, an outer ring, and rolling elements, the outer ring of the outer ring being fitted and fixed to the inner ring of the housing;
The outer ring is made of a metal material containing aluminum and iron,
The composition ratio of the weight of iron with respect to the sum of the weight of aluminum and the weight of iron decreases as it goes outward from the radially inner end of the outer ring.

  The outer ring may be formed of a plurality of separate members or may be integrated. For example, the outer ring may include an annular first member having a raceway surface and an annular second member that is fitted and fixed to the outer peripheral surface of the first portion. The outer ring may be an integral member that is fitted and fixed to the inner peripheral surface of the housing.

  In addition, the phrase “the composition ratio of the weight of iron to the sum of the weight of aluminum and the weight of iron decreases” means that the portion of the outer ring has the weight of aluminum as it goes outward in the radial direction. While the composition ratio of the iron weight to the sum of the iron weight does not change, in the entire outer ring, the iron weight relative to the sum of the aluminum weight and the iron weight increases in the radial direction. The case where the composition ratio is decreased is included.

  Further, in this specification, the composition ratio of the weight of iron to the sum of the weight of aluminum and the weight of iron (hereinafter referred to as iron weight composition ratio) is expressed as iron mass [g] / (aluminum mass [g]. + Iron mass [g]).

  Further, in this specification, the composition ratio of the weight of aluminum to the sum of the weight of aluminum and the weight of iron (hereinafter referred to as aluminum weight composition ratio) is expressed as mass of aluminum [g] / (mass of aluminum [g] + It is defined by the mass of iron [g]).

  Therefore, for example, when the outer ring is constituted by the first member and the second member, there is no aluminum in the entire region of the first member, and the second member goes outward in the radial direction. Accordingly, the case where the iron weight composition ratio decreases is included. This is because, in the entire area of the first member, the iron weight composition ratio is constant at 1 as it goes outward in the radial direction, whereas in the second member, the iron weight composition ratio is outward in the radial direction. It is because it decreases from 1 as it goes to.

  According to the present invention, as the iron weight composition ratio of the outer ring decreases from the radially inner end of the outer ring to the outer side, the iron content of the outer ring raceway surface is high. Become. Accordingly, it is possible to increase the iron content on the raceway surface, which requires hardness and is suitable for a high iron content. In addition, in the surface layer part of a raceway surface, it is preferable in the content rate of aluminum being zero (0).

  In addition, according to the present invention, the outer ring has an aluminum weight composition ratio that increases toward the outer side in the radial direction. Therefore, the outer ring can be reduced in weight compared to the iron outer ring.

  Further, according to the present invention, the outer ring has an aluminum weight composition ratio that increases toward the outer side in the radial direction, so the linear expansion coefficient of the housing made of aluminum or aluminum alloy and the outer side in the radial direction of the outer ring. The gap with the coefficient of linear expansion at the end of can be reduced to 0 (zero) or small. Therefore, the creep of the outer ring with respect to the housing can be suppressed even at a high temperature.

  Further, according to the present invention, since the outer ring has a configuration in which the aluminum weight composition ratio increases toward the outer side in the radial direction, the creep of the outer ring with respect to the housing can be achieved without forming a groove in the outer ring. Can be suppressed. Therefore, since it is not necessary to form a groove in the outer ring, the man-hours required for manufacturing the outer ring and the manufacturing cost of the outer ring can be reduced.

In one embodiment,
At least a part of the outer ring is manufactured by a powder metallurgy method using a powder containing iron powder and aluminum powder.

  The present inventor conducted a number of tests, and in such a method that there exists an interface between a region where the iron weight composition ratio is 0 and a region where the iron weight composition ratio is 1, When trying to join aluminum, I discovered that joining iron and aluminum would not work.

  On the other hand, the present inventor tries to join iron and aluminum by powder metallurgy so that there is no boundary between iron powder and aluminum so that the iron weight composition ratio gradually increases in one direction. In this case, it was confirmed that the joining of iron and aluminum was successful.

  According to the above embodiment, since at least a part of the outer ring is manufactured by powder metallurgy, the distribution of fluctuations in the radial direction of the iron weight composition ratio in at least a part of the outer ring is obtained as a distribution of desired fluctuations. And a close distribution.

  Further, according to the embodiment, since the iron weight composition ratio gradually decreases from the radially inner end of the outer ring toward the radially outer end, aluminum, iron and Can be bonded satisfactorily. Therefore, it is possible to realize both weight reduction by containing aluminum and securing of the hardness of the raceway surface due to the large content of iron at the radially inner end.

  Moreover, according to the said embodiment, since at least one part of the said outer ring is manufactured by the powder metallurgy method, an outer ring can be manufactured easily and cheaply.

In one embodiment,
The average particle diameter of the iron particles constituting the iron powder is different from the average particle diameter of the aluminum particles constituting the aluminum powder.

  According to the above embodiment, since the average particle size of the iron particles constituting the iron powder is different from the average particle size of the aluminum particles constituting the aluminum powder, the average particle is placed in the gap between the particles having the larger average particle size. Particles having a smaller diameter can easily enter, and the sealing performance at the boundary region between the two particles can be improved. Therefore, since it is in a close contact state in a powder state, it can be prevented that the boundary surface is peeled off or a defect is formed when it is hardened by sintering. Therefore, the outer ring can have a functionally gradient material in which iron and aluminum are in close contact.

In one embodiment,
The outer ring is
An annular first member having a raceway surface;
It has an annular second member that is fitted and fixed to the inner peripheral surface of the housing while being fitted and fixed to the first member.

  According to the said embodiment, while a 1st member can be manufactured with the steel material which does not contain aluminum, a 2nd member can be comprised with a functionally gradient material by a powder metallurgy method. Therefore, since the second member has a simple shape and can be manufactured at low cost, the second member can be easily and inexpensively inserted into the housing simply by inserting the second member between the first member and the housing. Creep of the outer ring can be suppressed.

  According to the rolling bearing mounting structure of the above embodiment, creep of the outer ring with respect to the housing can be suppressed. Moreover, according to the mounting structure of the rolling bearing of the said embodiment, a man-hour and manufacturing cost become small.

It is a schematic cross section of the axial direction of the mounting structure of the rolling bearing of 1st Embodiment of this invention. It is a schematic diagram which shows the arrangement | positioning state of the iron particle and aluminum particle in the local part of the 2nd member of the said outer ring | wheel. It is a schematic cross section of the axial direction of the attachment structure of the rolling bearing of 2nd Embodiment.

  Hereinafter, the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a schematic sectional view in the axial direction of a rolling bearing mounting structure according to a first embodiment of the present invention.

  This mounting structure of the rolling bearing constitutes a part of an alternator of an automobile whose operating temperature range is high. This rolling bearing mounting structure includes a housing 1 and a ball bearing 2, and the housing 1 is made of aluminum. The ball bearing 2 has a plurality of balls 12 as an example of an outer ring 10, an inner ring 11, and rolling elements.

  The outer ring 10 includes an annular first member 20 and an annular second member 21. The first member 20 has a raceway groove as a raceway surface on the inner peripheral surface thereof. The first member 20 has a cylindrical outer peripheral surface.

  The second member 21 is located outward in the radial direction of the first member 20. The second member 21 is a cylindrical member, and has a cylindrical inner peripheral surface and a cylindrical outer peripheral surface. The second member 21 is fixed by being fitted onto the cylindrical outer peripheral surface of the first member 20 by an interference fit. Further, the second member 21 is fixedly fitted to the inner peripheral surface of the housing 1 by an interference fit.

  The inner ring 11 is fixed by being fitted onto a rotating shaft of an alternator (not shown) by an interference fit. The inner ring 11 has a raceway groove as a raceway surface on the outer peripheral surface thereof. Further, the plurality of balls 12 are arranged at intervals in the circumferential direction between the raceway groove of the outer ring 10 and the raceway groove of the inner ring 11 while being held by the cage 28.

  Each of the first member 20, the inner ring 11 and the balls 12 is made of a steel material such as SUJ2 steel (high carbon chromium bearing steel), carburized and quenched steel such as SAE5120 carburized and quenched, and high-speed tool steel.

  On the other hand, the second member 21 is manufactured by a powder metallurgy method using a powder containing iron powder and aluminum powder. Here, SMF4040 is used as the iron powder, and an aluminum alloy such as alloy number 6063 is used as the aluminum powder. In addition, you may use iron powders other than the above, and aluminum powders other than the above. The iron-weight composition ratio of the second member 21 decreases from the radially inner end of the second member 21 to the radially outward direction of the second member 21.

  Here, in FIG. 1 showing the first embodiment and FIG. 3 showing the following embodiments, in each figure, the higher the degree of gray of gray scale, the higher the iron weight composition ratio. . As shown in FIG. 1, the inner surface layer portion in the radial direction of the second member 21 has an iron weight composition ratio of 1.

  Further, from the inner surface layer portion to the outer outer surface layer portion in the radial direction of the second member 21, the iron weight composition ratio decreases monotonously and gradually as it goes outward in the radial direction. In the outer surface layer portion, the iron weight composition ratio is 0 (zero) and the aluminum weight composition ratio is 1.

  Specifically, the second member 21 is formed as follows.

  First, an aluminum powder and an iron powder are prepared. Here, in the first embodiment, the average particle size of the prepared iron powder is smaller than the average particle size of the prepared aluminum powder.

  Next, the above two powders are mixed. In this mixing, it arrange | positions so that the ratio of the aluminum powder with respect to iron powder and aluminum powder may become high gradually as it goes to the metal mold | die of the 2nd member 21 in the radial direction of the 2nd member 21. Further, only iron powder is disposed at a location corresponding to the radially inner end of the second member of the mold, while corresponding to the radially outer end of the second member of the mold. Place only aluminum powder in the place.

  Subsequently, compression molding is performed. In compression molding, pressure is applied to the powder filled in the mold with upper and lower punches to form a compact called green compact or green compact. It is necessary that the prepared green compact has sufficient strength because the powder particles adhere to each other.

  Thereafter, sintering is performed. The green compact is fragile because it has sufficient adhesion between the powder particles but does not yet have an atomic bond. Therefore, sintering is performed by appropriately adjusting the sintering temperature, the sintering time, and the gas atmosphere in the sintering furnace. By sintering, the green compact is baked and hardened at a high temperature to make it sufficiently strong. In addition, as a method for performing both compression molding and sintering, there are a hot press method in which powder packed in a mold is compressed while heating, and a hot isostatic press method in which compression molding is performed in a high-temperature and high-pressure gas container. It can also be used. In this way, the second member 21 is created. In addition, you may perform sintering using the discharge plasma sintering method (SPS) which flows by flowing a large electric current.

  FIG. 2 is a schematic diagram showing an arrangement state of the iron particles 127 and the aluminum particles 120 in a local portion of the second member 21 of the outer ring 10 (see FIG. 1).

  In FIG. 2, an arrow A indicates the radial direction, and the upper side of the drawing is the outer side in the radial direction. Moreover, FIG. 2 is a figure which shows a principle and the dimension of the area | region where the aluminum particle 120 and the iron particle 127 are mixed in a radial direction differs from an actual dimension.

  As shown in FIG. 2, in this example, many aluminum particles 120 have substantially the same particle diameter, and many iron particles 127 also have substantially the same particle diameter. The average particle size of the aluminum particles 120 is larger than the average particle size of the iron particles 127. As shown in FIG. 2, in a region where the aluminum particles 120 and the iron particles 127 are mixed in the radial direction, the iron particles 127 having a small average particle diameter enter between the aluminum particles 120 having a large average particle diameter. Thus, the gap is small and a dense state is realized.

  According to the rolling bearing mounting structure of the first embodiment, the iron weight composition ratio of the end portion on the inner raceway surface side in the radial direction of the outer ring 10 is 1, and the first member 20 is made of SUJ2 steel ( High-carbon chromium bearing steel), carburizing and quenching steel such as SAE5120 carburizing and quenching, and high-speed tool steel and other steel materials, the hardness of the raceway groove is not problematic.

  Moreover, according to the mounting structure of the rolling bearing of the first embodiment, the weight ratio of the aluminum increases as the second member 21 goes radially outward, thereby reducing the weight of the second member 21. be able to. Therefore, the outer ring 10 can be reduced in weight.

  Further, according to the rolling bearing mounting structure of the first embodiment, the iron weight composition ratio of the end portion on the inner peripheral side of the second member 21 is 1, so that the inside of the first member 20 and the second member 21 is The difference in linear expansion coefficient from the end on the circumferential side can be made substantially 0 (zero). Therefore, at high temperatures, the tightening allowance between the second member 21 and the first member 20 is not reduced, and creep between the first member 20 and the second member 21 can be reliably prevented.

  Moreover, since the aluminum weight composition ratio of the outer peripheral end of the second member 21 is 1, the difference in linear expansion coefficient between the housing 1 and the outer peripheral end of the second member 21 is set to approximately 0 (zero). can do. Therefore, at high temperatures, the interference between the housing 1 and the second member 21 is not reduced, and creep between the housing 1 and the second member 21 can be reliably prevented.

  Further, according to the rolling bearing mounting structure of the first embodiment, the outer ring 10 has a configuration in which the aluminum weight composition ratio increases as it goes outward in the radial direction. Even if not formed, creep of the outer ring 10 with respect to the housing 1 can be suppressed. Therefore, since it is not necessary to form a groove in the outer ring 10, the man-hours required for manufacturing the outer ring 10 and the manufacturing cost of the outer ring can be reduced.

  Further, according to the rolling bearing mounting structure of the first embodiment, since the second member 21 that is a part of the outer ring 10 is manufactured by the powder metallurgy method, the second member 21 has an iron weight composition ratio. The distribution in the radial direction can be a distribution close to a desired distribution.

  Further, according to the rolling bearing mounting structure of the first embodiment, the iron weight composition ratio gradually decreases from the radially inner end of the outer ring 10 toward the radially outer side. Therefore, aluminum and iron can be bonded satisfactorily. Therefore, it is possible to realize both weight reduction by containing aluminum and securing the hardness of the raceway groove by containing a large amount of iron at the radially inner end.

  Moreover, according to the said embodiment, since at least one part of the said outer ring | wheel 10 is manufactured by the powder metallurgy method, the outer ring | wheel 10 can be manufactured easily and cheaply.

  In addition, according to the rolling bearing mounting structure of the first embodiment, since the average particle diameter of the iron particles 127 is different from the average particle diameter of the aluminum particles 120, iron easily enters the gaps in the aluminum, The sealing performance at the boundary region can be improved. Therefore, since it is in a close contact state in a powder state, it can be prevented that the boundary surface is peeled off or a defect is formed when it is hardened by sintering. Therefore, the second member 21 can have a functionally gradient material in which iron and aluminum are in close contact.

  In the rolling bearing mounting structure according to the first embodiment, a large number of aluminum particles 120 used to manufacture the second member 21 have substantially the same particle diameter, and are used to manufacture the second member 21. A number of iron particles 127 had substantially the same particle diameter, and the average particle diameter of the aluminum particles 120 was larger than the average particle diameter of the iron particles 127. However, in the present invention, the particle diameters of a large number of aluminum powders may vary widely, and the particle diameters of the aluminum particles may be different from each other. The difference in size may be different, and the particle sizes of the iron particles may be different from each other. In the present invention, the average particle size of the aluminum particles may be smaller than the average particle size of the iron particles. In the present invention, the average particle size of the aluminum particles and the average particle size of the iron particles may be substantially the same.

  In the rolling bearing mounting structure of the above embodiment, the rolling bearing is the ball bearing 2, but in this invention, the rolling bearing is a roller bearing (cylindrical roller bearing, conical) even if it is a double row ball bearing. The rolling element may be a ball arranged in a double row or a rolling element other than a ball such as a roller.

  Moreover, in the rolling bearing mounting structure of the above embodiment, the aluminum weight composition ratio increases from the radially inner surface layer of the second member 21 to the radially outer surface layer of the second member 21. It gradually increased from 0 (zero) to 1. However, in the present invention, for example, the aluminum weight composition ratio is from 0 (zero) to 1 as it goes from the radially inner surface layer portion of the second member to the radially outer surface layer portion of the second member. You may make it increase gradually to a small value. In this case, the housing is made of an aluminum alloy, and the composition ratio of the weight of aluminum to the sum of the weight of aluminum and the weight of iron in the housing is the weight of aluminum in the outer surface layer portion in the radial direction of the second member. Needless to say, the same composition ratio is preferable.

  FIG. 3 is a schematic cross-sectional view in the axial direction of the rolling bearing mounting structure of the second embodiment.

  The rolling bearing mounting structure of the second embodiment is significantly different from that of the first embodiment in that the outer ring is not composed of a plurality of members but the outer ring is an integral member.

  In the rolling bearing mounting structure of the second embodiment, the description of the operations and effects common to the rolling bearing mounting structure of the first embodiment will be omitted, and the rolling bearing mounting structure of the first embodiment will be omitted. Only different configurations, operational effects, and modifications will be described.

  This rolling bearing mounting structure includes a housing 101 and a ball bearing 102 as an example of a rolling bearing. The ball bearing 102 includes an outer ring 110, an inner ring 111, and a plurality of balls 112 as rolling elements, and is not shown. And two shield plates.

  The housing 101 is made of aluminum. The inner ring 111 has a raceway groove as a raceway surface on the outer periphery, and the outer ring 110 has a raceway groove as a raceway surface on the inner periphery. Each of the inner ring 111 and the ball 112 is made of a steel material such as SUJ2 steel (high carbon chromium bearing steel), carburized and hardened steel such as SAE5120 carburized and hardened, and high-speed tool steel.

  The plurality of balls 112 are arranged at intervals in the circumferential direction between the raceway grooves of the outer ring 110 and the raceway grooves of the inner ring 111 while being held by a cage (not shown). . The one shield plate is arranged so as to close one axial opening of the outer ring 110 and the inner ring 111, while the other shield plate is arranged in the axial direction of the outer ring 110 and the inner ring 111. It arrange | positions so that the other opening may be plugged up.

  The outer ring 110 is manufactured by the powder metallurgy method described in detail in the first embodiment. Specifically, the outer ring 110 is produced by powder metallurgy so that the outer peripheral side is aluminum and the inner peripheral side is iron. Moreover, the boundary area | region of aluminum and iron is comprised with the alloy of aluminum and iron. Specifically, between the outer peripheral side and the inner peripheral side, the iron weight component ratio increases from the outer peripheral side to the inner peripheral side, so that the material has an inclination function and the joining can be ensured. I am doing so. In the second embodiment, the average particle size of aluminum is set to a particle size different from the average particle size of iron so that the bonding is dense.

  Further, the surface layer portion 270 on the inner peripheral side of the outer ring 110 is hardened by high frequency to perform a hardening process so that it can function as a raceway groove.

  According to the rolling bearing mounting structure of the second embodiment, since the integral outer ring 110 having the functionally gradient material is used, a lightweight rolling bearing mounting structure that can reliably suppress creep can be realized.

  Further, according to the rolling bearing mounting structure of the second embodiment, since the outer ring 110 is an integral member, the number of parts can be reduced, and the handleability can be remarkably improved.

DESCRIPTION OF SYMBOLS 1,101 Housing 2,102 Ball bearing 10,110 Outer ring 11,111 Inner ring 12,112 Ball 20 First member 21 Second member 120 Aluminum particle 127 Iron particle

Claims (4)

An annular housing made of aluminum or aluminum alloy;
A rolling bearing comprising an inner ring, an outer ring, and rolling elements, the outer ring of the outer ring being fitted and fixed to the inner ring of the housing;
The outer ring is made of a metal material containing aluminum and iron,
A rolling bearing characterized in that the composition ratio of the weight of iron to the sum of the weight of aluminum and the weight of iron decreases from the radially inner end of the outer ring toward the outside. Mounting structure. In the rolling bearing mounting structure according to claim 1,
At least a part of the outer ring is manufactured by a powder metallurgy method using a powder containing iron powder and aluminum powder. In the rolling bearing mounting structure according to claim 2,
A rolling bearing mounting structure, wherein an average particle diameter of iron particles constituting the iron powder is different from an average particle diameter of aluminum particles constituting the aluminum powder. In the mounting structure of the rolling bearing according to any one of claims 1 to 3,
The outer ring is
An annular first member having a raceway surface;
A rolling bearing mounting structure comprising: an annular second member that is fitted and fixed to the inner peripheral surface of the housing while being fitted and fixed to the first member.