JP2010001943A - Bearing part and rolling bearing - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a bearing part composed of a β sialon sintered body usable even in an environment in which hard foreign matter intrudes inside a bearing, while stably securing sufficient durability, though at low cost, and a rolling bearing having the bearing part. <P>SOLUTION: At least one of an outer race 11, an inner race 12 and a ball 13 for constituting a deep groove ball bearing 1, is constituted of the sintered body expressed by a composition formula of Si<SB>6-Z</SB>Al<SB>Z</SB>O<SB>Z</SB>N<SB>8-Z</SB>, containing β sialon as main component, satisfying 1.0≤z≤2.0, and a residual part of an impurity. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a bearing component and a rolling bearing, and more particularly to a bearing component made of a sintered body mainly composed of β sialon and a rolling bearing provided with the bearing component.

  Ceramics such as silicon nitride and sialon are characterized by having a specific gravity smaller than steel and high corrosion resistance, as well as insulating properties. For this reason, when ceramics is used as a bearing component that is a component of a rolling bearing (including a hub unit) including a race member and rolling elements, for example, ceramics can be used as a material for the race member and rolling elements, the weight of the bearing can be reduced. In addition, it is possible to suppress damage due to corrosion of component parts, shortening of the life of rolling bearings due to electrolytic corrosion, and the like.

  In addition, a hub unit, which is a kind of rolling bearing, is often used in an environment where moisture may enter inside, and lubrication may be insufficient. Bearing parts such as rolling elements and race members made of ceramics have a feature that they are not easily damaged even in the above-mentioned insufficient lubrication environment. Therefore, for example, by using ceramics as a material for bearing parts, it is possible to improve the durability of the hub unit used in an insufficient lubrication environment.

  However, since ceramics such as silicon nitride and sialon have a higher manufacturing cost than steel, there is a problem that the manufacturing cost of a rolling bearing is significantly increased when ceramics are used as a material for bearing parts.

On the other hand, in recent years, a method for producing β sialon, which is a ceramic, at a low cost by producing it by a production process including a combustion synthesis method has been developed (for example, see Patent Documents 1 to 3). Therefore, it is possible to consider the production of a low-cost rolling bearing that employs this β sialon as the material of the component parts.
JP 2004-91272 A JP 2005-75652 A JP 2005-194154 A

  However, in order to employ the β sialon as a material for the bearing part, the bearing part made of β sialon needs to have a sufficient rolling fatigue life. The rolling fatigue life does not necessarily match the fracture strength of the member, and it cannot be said that the bearing parts made of β sialon have a sufficient rolling fatigue life. Therefore, there is a problem that it is not easy to stably secure sufficient durability even in a rolling bearing provided with bearing parts made of β sialon.

  Further, when β sialon which is not easily elastically deformed is employed as a material for the bearing part, the contact surface pressure between the race member as the bearing part and the rolling element as the bearing part tends to increase. Therefore, when a hard foreign substance enters between the race member and the rolling element, the race member and the rolling element are likely to be damaged. In particular, when one of the race member and the rolling element is made of a β sialon sintered body (sintered body containing β sialon as a main component) and the other is made of steel, it is formed on the race member or rolling element made of the steel. There is a risk of indentation. That is, when a rolling bearing provided with a bearing part made of β sialon sintered body is used in an environment where hard foreign matter enters the inside of the bearing, damage such as indentation is likely to occur in the bearing part, The life of the bearing may be reduced. Therefore, β sialon may not always be suitable as a material for bearing parts used in an environment where hard foreign matter enters the bearing.

  Accordingly, an object of the present invention is to provide a β that can be used stably even in an environment where a hard foreign object enters the inside of the bearing while being able to stably ensure sufficient durability while being inexpensive. It is to provide a bearing part made of a sialon sintered body and a rolling bearing (including a hub unit) provided with the bearing part.

  The bearing component according to the present invention is a bearing component which is a rolling member disposed on an annular raceway in contact with the raceway member or the raceway member in a rolling bearing. Compared to silicon nitride, this bearing part is made of ceramics that can suppress damage to the other bearing part when a hard foreign object is caught between the bearing part and the other bearing part. Yes.

  In the bearing part of the present invention, when a hard foreign object enters the inside of the rolling bearing including the bearing part of the present invention and the foreign object is caught between the bearing part and another bearing part, Damage to bearing parts is suppressed. As a result, according to the bearing component of the present invention, the biting resistance of the rolling bearing can be improved.

A bearing component according to one aspect of the present invention is a bearing component that is a rolling member disposed on an annular raceway in contact with the raceway member or the raceway member in a rolling bearing. The bearing component _is represented by a composition formula of _{Si 6-Z Al Z O Z} N 8-Z, as a main component β-sialon satisfying 1.0 ≦ z ≦ 2.0, a sintered body consisting of the balance impurities Composed.

The bearing component in the other aspect of this invention is a bearing component which is a rolling element arrange | positioned on an annular | circular shaped track | truck in contact with a track member or the said track member in a rolling bearing. The bearing component _is represented by a composition formula of _{Si 6-Z Al Z O Z} N 8-Z, as a main component β-sialon satisfying 1.0 ≦ z ≦ 2.0, the balance being sintering aid and impurities It is comprised from the sintered compact which becomes.

  The inventor has investigated in detail the relationship between the rolling fatigue life of a bearing component mainly composed of β sialon and the configuration of the bearing component. As a result, the following knowledge was obtained and the present invention was conceived.

  That is, the β sialon described above can be manufactured having various compositions in which the value of z (hereinafter referred to as z value) is 0.1 or more by employing a manufacturing process including combustion synthesis. In general, the hardness that greatly affects the rolling fatigue life hardly changes in the range of the z value of 4.0 or less that is easy to manufacture. However, when the relationship between the rolling fatigue life and z value of a bearing part made of a sintered body containing β sialon as a main component is investigated in detail, if the z value exceeds 3.5, the rolling fatigue life of the bearing part is determined. Was found to drop significantly.

  More specifically, when the z value is in the range of 0.1 or more and 3.5 or less, the rolling fatigue life is almost the same, and if the operation time of the rolling bearing exceeds a predetermined time, the surface of the bearing component is peeled off. Occurs and breaks. On the other hand, if the z value exceeds 3.5, the bearing parts are likely to be worn, resulting in a significant reduction in rolling fatigue life. That is, the failure mode of the bearing part made of β sialon sintered body changes at the boundary where the z value is 3.5, and if the z value exceeds 3.5, the rolling fatigue life is significantly reduced. The phenomenon became clear. Therefore, in a bearing part made of a β sialon sintered body, the z value needs to be 3.5 or less in order to ensure a stable and sufficient life.

  On the other hand, as described above, β sialon can be manufactured at a low cost by being manufactured by a manufacturing process including combustion synthesis. However, it has been found that when the z value is less than 0.1, it is difficult to perform the combustion synthesis. Therefore, in order to manufacture a bearing part made of a β sialon sintered body at a low cost, the z value needs to be 0.1 or more.

  Further, the present inventor, in an environment in which hard foreign matter enters the inside of the bearing, the mating member of the bearing part made of the β sialon sintered body (the race member or the rolling member contacting the bearing part made of the β sialon sintered body). The relationship between the aggression to the moving object and the z value was investigated in detail. As a result, it was found that when the z value is less than 1.0, the counterpart member is likely to be damaged, and when the z value exceeds 2.0, the bearing component made of the sintered body is easily damaged. Here, the hard foreign matter is a solid having a hardness of HV800 or higher, and examples thereof include high-speed steel used for cutting tools and the like, alumina used for abrasive grains for grinding and lapping, silicon carbide, and the like.

  That is, when the z value decreases, the strength of the material constituting the bearing component tends to increase. However, if the z value is lowered, the bearing parts are less likely to be elastically deformed, so that the contact area between the bearing parts is reduced and the contact surface pressure is increased. As a result, when a hard foreign substance enters between the race member and the rolling element, damage is likely to occur on the counterpart member facing the bearing component made of the sintered body. On the other hand, when the z value of the bearing component increases, the bearing component is easily elastically deformed, so that the contact area between the bearing components increases and the contact surface pressure decreases. However, on the other hand, when the z value of the bearing part increases, the strength of the material constituting the bearing part tends to decrease accordingly. For this reason, the bearing part itself is easily damaged by the hard foreign matter. Therefore, it is necessary for the z value of the bearing component to be within a range that can ensure a balance between the strength of the material constituting the bearing component and the reduction of the contact surface pressure between the bearing components.

  More specifically, when the z value of the bearing part made of the β sialon sintered body is less than 1.0, the influence of the increase of the contact surface pressure becomes large. Therefore, when a hard foreign substance enters between the race member and the rolling element, the indentation formed on the mating member becomes large, and damage such as peeling due to this tends to occur. As a result, the rolling fatigue life of a rolling bearing provided with a bearing component made of a β sialon sintered body is reduced. Therefore, when used in an environment where hard foreign matter enters the inside of the bearing, the z value of the bearing component made of the β sialon sintered body needs to be 1.0 or more.

  On the other hand, when the z value of the bearing part made of β sialon sintered body exceeds 2.0, the influence of the strength reduction of the material constituting the bearing part exceeds the effect of reducing the contact surface pressure. For this reason, when a hard foreign object enters between the race member and the rolling element, the bearing part itself made of the β sialon sintered body is damaged, and the rolling fatigue life is reduced. Further, when the z value exceeds 2.0, as the contact area between the bearing parts increases, the frictional force acting between the bearing parts increases and the problem that the bearing torque rises also occurs. Therefore, when used in an environment where hard foreign matter enters the inside of the bearing, the z value of the bearing part made of the β sialon sintered body needs to be 2.0 or less.

On the other hand, the bearing component according to one aspect of the present invention is mainly composed of β sialon represented by a composition formula of Si _6-Z Al _Z O _Z N _8-Z and satisfying 1.0 ≦ z ≦ 2.0. And a sintered body composed of the remaining impurities. Therefore, according to the bearing component in one aspect of the present invention, it is possible to stably ensure sufficient durability while being inexpensive, and in an environment where hard foreign matter enters the bearing. It is possible to provide a bearing component made of a β sialon sintered body that can also be used.

  Further, the bearing component in another aspect of the present invention basically has the same configuration as the bearing component in one aspect of the present invention, and exhibits the same effects. However, the bearing component according to another aspect of the present invention is different from the bearing component according to one aspect of the present invention in that a sintering aid is included in consideration of the application of the bearing component and the like. According to the bearing component in another aspect of the present invention, it is easy to lower the porosity of the sintered body by adopting the sintering aid, and β sialon sintering capable of stably ensuring sufficient durability. It is possible to easily provide a bearing component composed of a combined body.

  As the sintering aid, at least one of magnesium (Mg), aluminum (Al), silicon (Si), titanium (Ti), rare earth element oxide, nitride, and oxynitride is employed. be able to. In addition, in order to achieve the same effect as the bearing component according to one aspect of the present invention, the sintering aid is desirably 20% by mass or less in the sintered body.

  Preferably, in the above-described bearing component, a dense layer that is a layer having a higher density than the inside is formed in a region including a rolling contact surface that is a surface in contact with another bearing component.

  In a bearing component made of a sintered body containing β sialon as a main component as described above, the denseness greatly affects the rolling fatigue life. On the other hand, according to the said structure, a rolling fatigue life improves because the dense layer which is a layer denser than the inside is formed in the area | region containing a rolling surface. As a result, it is possible to provide a bearing component made of a β sialon sintered body capable of stably ensuring sufficient durability.

  Here, the high-density layer is a layer having a low porosity (high density) in the sintered body, and can be investigated as follows, for example. First, the bearing part is cut in a cross section perpendicular to the surface of the bearing part, and the cross section is mirror-wrapped. Thereafter, the mirror-wrapped cross section is photographed with oblique light (dark field) of an optical microscope at, for example, about 50 to 100 times and recorded as an image of 300 DPI (Dot Per Inch) or more. At this time, the white region observed as a white region corresponds to a region with high porosity (low density). Therefore, a region where the area ratio of the white region is low is denser than a region where the area ratio is high. Then, after binarizing the image recorded using the image processing device with the luminance threshold, the area ratio of the white area is measured, and the denseness of the photographed area can be known from the area ratio.

  That is, in the bearing component, preferably, a dense layer that is a layer having a lower area ratio of the white region than the inside is formed in the region including the rolling surface. In addition, it is preferable to perform the said imaging | photography at 5 or more places at random, and to evaluate the said area ratio by the average value. Moreover, the area ratio of the said white area | region inside a bearing component is 15% or more, for example. In order to further improve the rolling fatigue life of the bearing component, the dense layer preferably has a thickness of 100 μm or more.

  Preferably, in the bearing component, when the cross section of the dense layer is observed with oblique light from an optical microscope, the area ratio of the white region observed as a white region is 7% or less.

  By improving the denseness of the dense layer to such an extent that the area ratio of the white region is 7% or less, the rolling fatigue life of the bearing component is further improved. Therefore, the above configuration can further improve the rolling fatigue life of the bearing component of the present invention.

  Preferably, in the bearing component, a high-density layer, which is a layer having a higher density than other areas in the dense layer, is formed in a region including the surface of the dense layer.

  By forming the denser layer having a higher denseness in the region including the surface of the dense layer, the durability against rolling fatigue of the bearing component is further improved, and the rolling fatigue life is further improved.

  Preferably, in the bearing component, when the cross section of the high-density layer is observed with oblique light from an optical microscope, the area ratio of the white region observed as a white region is 3.5% or less.

  By improving the denseness of the highly dense layer to such an extent that the area ratio of the white region is 3.5% or less, the rolling fatigue life of the bearing component is further improved. Therefore, the above configuration can further improve the rolling fatigue life of the bearing component of the present invention.

  The rolling bearing according to the present invention includes a race member and a plurality of rolling elements that are in contact with the race member and disposed on an annular raceway. At least one of the race member and the rolling element is the bearing component of the present invention.

  According to the rolling bearing of the present invention, it is possible to stably ensure sufficient durability while being inexpensive, and can be used even in an environment where hard foreign matter enters the inside of the bearing. It is possible to provide a rolling bearing including a bearing component made of a β sialon sintered body.

  In the rolling bearing, one of the race member and the rolling element may be the bearing component of the present invention, and the other of the race member and the rolling element may be a bearing component made of steel. In this case, the hardness of the surface of the bearing component made of steel is preferably HV680 or more.

  Thereby, even when used in an environment where hard foreign matter enters the inside of the bearing, it is possible to suppress the occurrence of damage in the bearing component made of steel that comes into contact with the bearing component made of the β sialon sintered body.

  As is apparent from the above description, according to the bearing component and the rolling bearing of the present invention, while being inexpensive, it is possible to stably ensure sufficient durability, and hard foreign matter inside the bearing. It is possible to provide a bearing component made of a β sialon sintered body that can be used even in an environment where the intrusion occurs, and a rolling bearing including the bearing component.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following drawings, the same or corresponding parts are denoted by the same reference numerals, and description thereof will not be repeated.

(Embodiment 1)
FIG. 1 is a schematic cross-sectional view showing a configuration of a deep groove ball bearing as a rolling bearing in the first embodiment which is an embodiment of the present invention. FIG. 2 is a schematic partial cross-sectional view showing an enlarged main part of FIG. With reference to FIG. 1 and FIG. 2, the deep groove ball bearing as a rolling bearing in Embodiment 1 is demonstrated.

  Referring to FIG. 1, a deep groove ball bearing 1 includes an annular outer ring 11 as a race member, an annular inner ring 12 as a race member disposed inside the outer ring 11, and an outer ring 11 and an inner ring 12. And a plurality of balls 13 as rolling elements that are arranged and held by an annular cage 14. An outer ring rolling surface 11 </ b> A is formed on the inner circumferential surface of the outer ring 11, and an inner ring rolling surface 12 </ b> A is formed on the outer circumferential surface of the inner ring 12. And the outer ring | wheel 11 and the inner ring | wheel 12 are arrange | positioned so that 12A of inner ring | wheel rolling surfaces and 11A of outer ring | wheels may mutually oppose. Further, the plurality of balls 13 are in contact with the inner ring rolling surface 12A and the outer ring rolling surface 11A at the ball rolling surface 13A, and are arranged at a predetermined pitch in the circumferential direction by the cage 14, thereby causing an annular track. It is held so that it can roll freely. With the above configuration, the outer ring 11 and the inner ring 12 of the deep groove ball bearing 1 are rotatable relative to each other.

Referring now to FIG. 2, the outer ring 11, inner ring 12 and ball 13 serving as a bearing component of the present embodiment _is represented by a composition formula of _{Si 6-Z Al Z O Z} N 8-Z, 1. It is comprised from the sintered compact which has (beta) sialon which satisfy | fills 0 <= z <= 2.0 as a main component, and consists of remainder impurities. And in the region including the outer ring rolling surface 11A, the inner ring rolling surface 12A, and the ball rolling surface 13A, which are rolling surfaces of the outer ring 11, the inner ring 12, and the ball 13, it is more dense than the inner 11C, 12C, 13C. The outer ring dense layer 11B, the inner ring dense layer 12B, and the ball dense layer 13B, which are higher layers, are formed. When the cross sections of the outer ring dense layer 11B, the inner ring dense layer 12B, and the ball dense layer 13B are observed with oblique light of an optical microscope, the area ratio of the white region observed as a white region is 7% or less. Therefore, the deep groove ball bearing 1 according to the present embodiment is inexpensive and can stably ensure sufficient durability, and is also used in an environment where hard foreign matter enters the inside of the bearing. This is a rolling bearing provided with bearing parts (outer ring 11, inner ring 12 and ball 13) made of a β sialon sintered body. The impurities include inevitable impurities including those derived from raw materials or those mixed in the manufacturing process.

  In the present embodiment, the outer ring 11, the inner ring 12 and the ball 13 as bearing parts may be composed of a sintered body containing β sialon as a main component and the remaining sintering aid and impurities. . By including a sintering aid, it is easy to reduce the porosity of the sintered body, and a rolling bearing provided with a bearing part made of a β sialon sintered body that can stably ensure sufficient durability. Can be provided easily. The impurities include inevitable impurities including those derived from raw materials or those mixed in the manufacturing process.

  Furthermore, referring to FIG. 2, the region including outer ring rolling surface 11 </ b> A, inner ring rolling surface 12 </ b> A and ball rolling surface 13 </ b> A that are the surfaces of outer ring dense layer 11 </ b> B, inner ring dense layer 12 </ b> B, and ball dense layer 13 </ b> B includes The outer ring high-density layer 11D, the inner ring high-density layer 12D, and the ball high-density layer 13D, which are denser layers than the other regions in the outer ring dense layer 11B, the inner ring dense layer 12B, and the ball dense layer 13B, are formed. Yes. When cross sections of the outer ring high-density layer 11D, the inner ring high-density layer 12D, and the ball high-density layer 13D are observed with oblique light from an optical microscope, the area ratio of the white region observed as a white region is 3.5% or less. It has become. Thereby, the durability with respect to rolling fatigue of the outer ring 11, the inner ring 12 and the ball 13 is further improved, and the rolling fatigue life is further improved.

  FIG. 3 is a schematic cross-sectional view showing a configuration of a thrust needle roller bearing as a rolling bearing in a modification of the first embodiment. FIG. 4 is a schematic partial cross-sectional view showing, in an enlarged manner, main portions of the bearing ring included in the thrust needle roller bearing of FIG. FIG. 5 is an enlarged schematic sectional view showing the needle roller provided in the thrust needle roller bearing of FIG. With reference to FIGS. 3-5, the thrust needle roller bearing as a rolling bearing in the modification of Embodiment 1 is demonstrated.

  3-5, the thrust needle roller bearing 2 has basically the same configuration as the deep groove ball bearing 1 described with reference to FIG. 1 and exhibits the same effects. However, the thrust needle roller bearing 2 is different from the deep groove ball bearing 1 in the configuration of the raceway member and the rolling element. That is, the thrust needle roller bearing 2 has a disk-like shape, and a pair of race rings 21 as race members disposed so that one main surfaces thereof face each other, and a plurality of needle rollers 23 as rolling elements. And an annular retainer 24. The plurality of needle rollers 23 are in contact with the raceway rolling surface 21A formed on the main surfaces of the pair of raceways 21 facing each other on the roller raceway 23A, which is the outer circumferential surface thereof, and in the circumferential direction by the cage 24. By being arranged at a predetermined pitch, it is held so as to roll on an annular track. With the above configuration, the pair of race rings 21 of the thrust needle roller bearing 2 can rotate relative to each other.

  Here, the bearing ring 21 and the needle roller 23 as bearing parts in the present modification correspond to the outer ring 11 or the inner ring 12 and the ball 13 described above, respectively, and are made of the same β-sialon sintered body and have the same It has inner portions 21C, 23C, a dense layer (track ring dense layer 21B, roller dense layer 23B) and a high dense layer (track ring high dense layer 21D, roller high dense layer 23D). Therefore, the thrust needle roller bearing 2 in the present modification can be stably secured with sufficient durability while being inexpensive, and is also used in an environment where hard foreign matter enters the inside of the bearing. It is a rolling bearing provided with bearing parts (orbital ring 21, needle roller 23) made of a β sialon sintered body.

  Next, the manufacturing method of the rolling bearing in Embodiment 1 which is one embodiment of this invention is demonstrated. FIG. 6 is a diagram showing an outline of a method for manufacturing a rolling bearing in the first embodiment which is an embodiment of the present invention. Moreover, FIG. 7 is a figure which shows the outline of the manufacturing method of the bearing components contained in the manufacturing method of the rolling bearing in Embodiment 1 of this invention.

  Referring to FIG. 6, in the method for manufacturing a rolling bearing in the present embodiment, first, a race member manufacturing process for manufacturing a race member and a rolling element manufacturing process for manufacturing a rolling element are performed. Specifically, in the track member manufacturing process, the outer ring 11, the inner ring 12, the track ring 21, and the like are manufactured. On the other hand, in the rolling element manufacturing process, balls 13 and needle rollers 23 are manufactured.

  And the assembly process which assembles a rolling bearing is implemented by combining the track member manufactured in the track member manufacturing process, and the rolling element manufactured in the rolling element manufacturing process. Specifically, for example, the deep groove ball bearing 1 is assembled by combining the outer ring 11 and the inner ring 12 and the ball 13. And a race member manufacturing process and a rolling element manufacturing process are implemented using the following manufacturing methods of bearing parts, for example.

Referring to FIG. 7, in the method of manufacturing a bearing component in the present embodiment, first, a β sialon powder preparation step of preparing β sialon powder is performed. In the β sialon powder preparation step, for example, by a production process employing a combustion synthesis method, it is represented by a composition formula of Si _6-Z Al _Z O _Z N _8-Z and satisfies 1.0 ≦ z ≦ 2.0. Sialon powder can be produced at low cost.

  Next, a mixing step is performed in which a sintering aid is added to and mixed with the β sialon powder prepared in the β sialon powder preparation step. This mixing step can be omitted if no sintering aid is added.

  Next, referring to FIG. 7, a molding step of molding the β sialon powder or the mixture of the β sialon powder and the sintering aid into a schematic shape of the bearing component is performed. Specifically, by applying a molding method such as press molding, cast molding, extrusion molding, rolling granulation, etc. to the above β sialon powder or a mixture of β sialon powder and a sintering aid, bearing parts Thus, a molded body formed into a schematic shape such as the outer ring 11, the inner ring 12, the ball 13, the race ring 21, and the needle roller 23 is manufactured.

  Next, a pre-sintering processing step is performed in which the surface of the molded body is processed so that the molded body has a shape closer to the shape of a desired bearing part after sintering. Specifically, by applying a processing method such as green body processing, the molded body becomes a shape closer to the shape of the outer ring 11, the inner ring 12, the ball 13, the race ring 21, the needle roller 23, etc. after sintering. To be processed. This pre-sintering processing step can be omitted when a shape sufficiently close to the shape of a desired bearing part is obtained after sintering at the stage where the molded body is formed in the forming step.

  Next, referring to FIG. 7, a sintering step is performed in which the molded body is sintered. Specifically, the molded body is heated and sintered under a pressure of 1 MPa or less, for example, by heater heating, electromagnetic wave heating by microwaves or millimeter waves, etc., so that the outer ring 11, inner ring 12, ball 13, a sintered body having a schematic shape such as the race 21 and the needle roller 23 is produced. Sintering is performed by heating the molded body to a temperature range of 1550 ° C. or higher and 1800 ° C. or lower in an inert gas atmosphere or a mixed gas atmosphere of nitrogen and oxygen. As the inert gas, helium, neon, argon, nitrogen, or the like can be employed, but nitrogen is preferably employed from the viewpoint of reducing manufacturing costs.

  Next, a finishing process for completing the bearing component is performed by processing the surface of the sintered body produced in the sintering process and performing a finishing process in which a region including the surface is removed. Specifically, the outer ring 11, inner ring 12, ball 13, bearing ring 21, needle roller 23, and the like as bearing parts are completed by polishing the surface of the sintered body produced in the sintering step. The bearing component in the present embodiment is completed through the above steps.

  Here, as a result of sintering in the above-described sintering step, a region having a thickness of about 500 μm from the surface of the sintered body is denser than the inside, and when the cross section is observed with oblique light of an optical microscope, a white region is obtained. A dense layer in which the area ratio of the observed white region is 7% or less is formed. Furthermore, the region having a thickness of about 150 μm from the surface of the sintered body has a higher density than the other regions in the dense layer, and is observed as a white region when the cross section is observed with an oblique light of an optical microscope. A highly dense layer in which the area ratio of the white region is 3.5% or less is formed. Therefore, in the finishing step, it is preferable that the thickness of the sintered body to be removed is 150 μm or less particularly in a region to be a rolling surface. As a result, a high-density layer remains in the region including the outer ring rolling surface 11A, the inner ring rolling surface 12A, the ball rolling surface 13A, the raceway rolling surface 21A, and the roller rolling surface 23A, and the rolling fatigue of the bearing parts. Lifespan can be improved.

  The sintering step is preferably performed under a pressure of 0.01 MPa or higher in order to suppress the decomposition of β sialon, and more preferably performed under a pressure of atmospheric pressure or higher in consideration of cost reduction. Moreover, in order to form a dense layer while suppressing manufacturing costs, the sintering process is preferably performed under a pressure of 1 MPa or less.

(Embodiment 2)
FIG. 8 is a schematic cross-sectional view showing a configuration of a hub unit which is a rolling bearing in the second embodiment which is an embodiment of the present invention. FIG. 9 is a schematic partial cross-sectional view showing an enlarged main part of FIG. With reference to FIG. 8 and FIG. 9, the hub unit in Embodiment 2 is demonstrated.

  Referring to FIGS. 8 and 9, the hub unit 3 has basically the same configuration as the deep groove ball bearing 1 described with reference to FIG. However, the hub unit 3 is different from the deep groove ball bearing 1 in the configuration of the raceway member and the rolling element. That is, the hub unit 3 is a device that is interposed between the wheel and the vehicle body and supports the wheel rotatably with respect to the vehicle body. The hub unit 3 includes an outer ring 31, which is a race member, a hub ring 32 and an inner ring 33, and a plurality of balls 34 as rolling elements.

  The outer ring 31 as an outer member is an annular track member having rolling surfaces 31A1 and 31A2 formed in two rows on the inner peripheral surface. The hub wheel 32 as an inner member is a track member that has a rolling surface 32A that faces one rolling surface 31A1 of the outer ring 31, and is disposed so that a part thereof is surrounded by the outer ring 31. The inner ring 33 as an inner member has a rolling surface 33A opposite to the other rolling surface 31A2 of the outer ring 31, and is fitted and fixed so as to contact a part of the outer peripheral surface of the hub wheel 32. The ring member is an orbital member having an annular shape fixed to the hub wheel 32 by fitting the ring 38 so as to contact a part of the outer peripheral surface of the hub wheel 32.

  The plurality of balls 34 are in contact with one rolling surface 31A1 of the outer ring 31 and the rolling surface 32A of the hub wheel 32, and are arranged at a predetermined pitch in the circumferential direction by an annular retainer 39A. A double row (two rows) of rows arranged in contact with the other rolling surface 31A2 of the outer ring 31 and the rolling surface 33A of the inner ring 33 and arranged at a predetermined pitch in the circumferential direction by an annular retainer 39B. ) Is arranged on a ring-shaped orbit. With the above configuration, the outer ring 31 as the outer member and the hub ring 32 and the inner ring 33 as the inner members can rotate relative to each other.

  Further, the hub wheel 32 has a hub wheel flange 35, and a hub wheel through hole 35 </ b> A is formed in the hub wheel flange 35. The hub wheel flange 35 and the wheel (not shown) are fixed to each other by a bolt 36 inserted into the hub wheel through hole 35A. On the other hand, the outer ring 31 has an outer ring flange 37, and an outer ring through hole 37 </ b> A is formed in the outer ring flange 37. The outer ring flange 37 and a suspension device (not shown) fixed to the vehicle body are fixed to each other by a bolt (not shown) inserted into the outer ring through hole 37A. With the above configuration, the hub unit 3 is interposed between the wheel and the vehicle body, and rotatably supports the wheel with respect to the vehicle body.

  That is, the hub unit 3 in the present embodiment is a hub unit that is interposed between the wheel and the vehicle body and rotatably supports the wheel with respect to the vehicle body. The hub unit 3 is formed with an outer ring 31 as an outer member having an inner peripheral surface on which annular rolling surfaces 31A1 and 31A2 are formed, and an annular rolling surface 32A facing the rolling surface 31A1 of the outer ring 31. Then, a hub wheel 32 as an inner member disposed so that at least a part thereof is surrounded by the inner peripheral surface of the outer ring 31, and an annular rolling surface 33A facing the rolling surface 31A2 of the outer ring 31 are formed. And an inner ring 33 as an inner member disposed so that at least a part of the inner ring is surrounded by the inner circumferential surface of the outer ring 31. Further, the hub unit 3 is in contact with the rolling surfaces 31A1 and 31A2 of the outer ring 31 and the rolling surfaces 32A and 33A of the hub wheel 32 and the inner ring 33 at the ball rolling surface 34A, and is arranged on an annular track. The ball 34 is provided.

  Here, referring to FIG. 8 and FIG. 9, the outer ring 31, the hub ring 32, the inner ring 33, and the ball 34 as bearing parts (hub unit bearing parts) in the present embodiment are the same as those in the first embodiment. Corresponding to the outer ring 11, the inner ring 12 and the ball 13 and made of the same β sialon sintered body, the same inner 31C, 32C, 33C, 34C, dense layer (outer ring dense layer 31B, hub ring dense layer 32B, inner ring A dense layer 33B, a ball dense layer 34B) and a high dense layer (outer ring high dense layer 31D, hub ring high dense layer 32D, inner ring high dense layer 33D, ball high dense layer 34D). For this reason, the hub unit 3 in the present embodiment is inexpensive and can stably ensure sufficient durability, and is also used in an environment where hard foreign matter enters the bearing. It is a rolling bearing provided with bearing parts (outer ring 31, hub ring 32, inner ring 33, ball 34) made of a β sialon sintered body capable of being. The hub unit 3 as a rolling bearing in the second embodiment and the outer ring 31, the hub wheel 32, the inner ring 33, and the ball 34 as bearing components provided in the hub unit 3 are manufactured in the same manner as in the first embodiment. be able to.

  In the above embodiment, the deep groove ball bearing, the thrust needle roller bearing and the hub unit, and the bearing components provided therein are described as examples of the rolling bearing and bearing component of the present invention. However, the rolling bearing of the present invention is not limited thereto. Absent. For example, the race member may be a shaft or a plate used so that the rolling elements roll on the surface. That is, the raceway member which is a bearing component of the present invention may be a member on which a rolling surface for rolling of the rolling element is formed. Further, the rolling bearing of the present invention may be a thrust ball bearing or a radial roller bearing.

  In the above embodiment, the case where both the race member and the rolling element of the rolling bearing of the present invention are the bearing parts of the present invention made of the β sialon sintered body has been described. However, the rolling bearing of the present invention is not limited to this. Not limited to. In the rolling bearing of the present invention, at least one of the race member and the rolling element may be the bearing component of the present invention. And when any one of a track member and a rolling element is the bearing component of this invention, when the manufacturing cost of a rolling bearing is considered, it is preferable that a rolling element is a bearing component of this invention.

  At this time, the material of the race member in the rolling bearing of the present invention is not particularly limited. For example, steel, specifically, bearing steel such as JIS standard SUJ2, high carbon steel such as S53C, and carburized steel such as SCr420 and SCM420 are adopted. can do.

  Furthermore, the bearing component and the rolling bearing of the present invention are particularly suitable as a bearing component and a rolling bearing that are used in an environment where hard foreign matter enters the inside of the bearing. Specifically, for example, in addition to the hub unit bearing component and the hub unit including the hub unit bearing component, an automotive bearing component used for an automotive bearing such as a transmission, an engine, an electrical accessory, and the like. Automotive bearings having bearing parts, aircraft engine bearing parts used for aircraft engine bearings, aircraft engine bearings including the aircraft engine bearing parts, construction machine bearing parts used for construction machine bearings, and the like A bearing for a construction machine having bearing parts for a construction machine, and a rotating member that rotates in response to the rotation of a main shaft or a main shaft of a wind turbine, is rotatably supported with respect to the main shaft or a member disposed so as to face the rotating member. Wind turbine bearing parts used for wind turbine bearings and wind turbine bearings equipped with the wind turbine bearing parts Bearing component and a rolling bearing of the present invention is particularly suitable.

  Embodiment 1 of the present invention will be described below. Rolling bearings having rolling elements made of β sialon sintered bodies having various z values were produced, and tests for investigating the relationship between the z value and the rolling fatigue life (durability) were conducted. The test procedure is as follows.

  First, a method for producing a test bearing to be tested will be described. First, a β sialon powder prepared by a combustion synthesis method with a z value in the range of 0.1 to 4 is prepared, and is basically the same as the rolling element manufacturing method described in the first embodiment based on FIG. By this method, a rolling element having a z value of 0.1 to 4 was produced. A specific manufacturing method is as follows. First, β sialon powder refined to submicron, aluminum oxide (manufactured by Sumitomo Chemical Co., Ltd., AKP30) and yttrium oxide (manufactured by HC Starck Co., Ltd., Yttrium oxide grade C) as a ball mill Were mixed by wet mixing. Then, granulation was performed with a spray dryer to produce granulated powder. The granulated powder was molded into a sphere with a mold and further pressurized by cold isostatic pressing (CIP) to obtain a spherical molded body.

  Subsequently, after performing atmospheric pressure sintering as primary sintering for the molded body, the sintered spheres are obtained by performing HIP (Hot Isostatic Press) in a nitrogen atmosphere at a pressure of 200 MPa. Manufactured. Next, lapping was performed on the sintered spheres to obtain 3/8 inch ceramic spheres (JIS grade G5). And the bearing of the JIS standard 6206 model number was produced in combination with the bearing ring made from bearing steel (JIS standard SUJ2) prepared separately (Examples A to C, Reference examples A to E, and Comparative examples B to C). For comparison, a rolling element made of silicon nitride, that is, a rolling element having a z value of 0 was also produced in the same manner as the rolling element made of β sialon, and similarly assembled to a bearing (Comparative Example A).

  Next, test conditions will be described. For the bearing of JIS standard 6206 model number produced as described above, maximum contact surface pressure Pmax: 3.2 GPa, bearing rotation speed: 2000 rpm, lubrication: circulating oil supply of turbine oil VG68 (clean oil), test temperature: room temperature, A fatigue test was performed under the conditions of The vibration of the bearing during operation is monitored by the vibration detection device, and the test is stopped when the rolling element is damaged and the vibration of the bearing exceeds a predetermined value. Recorded as bearing life. In addition, after the test was stopped, the bearing was disassembled to confirm the damaged state of the rolling elements.

  Table 1 shows the test results of this example. In Table 1, the life in each Example, Reference Example, and Comparative Example is expressed as a life ratio with the life in Comparative Example A (silicon nitride) as 1. The damage form is described as “peeling” when peeling occurs on the surface of the rolling element, and “wearing” when the surface is worn without peeling and the test is stopped.

  Referring to Table 1, Examples A to C and Reference Examples A to E of the present invention having z values of 0.1 or more and 3.5 or less are inferior to silicon nitride (Comparative Example A). Has no lifetime. Further, the form of breakage is “peeling” as in the case of silicon nitride. On the other hand, in Comparative Example B in which the z value exceeds 3.5 and is outside the scope of the present invention, the life is significantly reduced and wear is observed on the rolling elements. That is, in Comparative Example B in which the z value is 3.8, it is considered that although the rolling element finally peeled, the wear on the rolling element affected and the life was significantly reduced. Furthermore, in Comparative Example C in which the z value is 4, the wear of the rolling elements proceeds in a very short time, and the durability of the rolling bearing is significantly reduced.

  As described above, when the z value is in the range of 0.1 to 3.5, the durability of the rolling bearing provided with the rolling element made of the sialon sintered body is that the rolling element made of the silicon nitride sintered body is It is almost equivalent to the rolling bearing provided. On the other hand, when the z value exceeds 3.5, the rolling elements are likely to be worn, and the rolling fatigue life is significantly reduced due to this. Furthermore, it has been clarified that when the z value increases, the cause of breakage of the rolling element composed of β sialon changes from “peeling” to “wear”, and the rolling fatigue life is significantly reduced. In this way, by providing a z-value of 0.1 or more and 3.5 or less, a rolling element made of a β sialon sintered body capable of stably securing sufficient durability while being inexpensive is provided. It was confirmed that a rolling bearing could be provided.

  In addition, referring to Table 1, in Reference Example E having a z value exceeding 3.5, a slight amount of wear was generated on the rolling elements, and the service life was also in Examples A to C and Reference Examples A to A. It is lower than D. From this, it can be said that the z value is desirably 3 or less in order to ensure sufficient durability more stably.

  Embodiment 2 of the present invention will be described below. Rolling bearings with rolling elements made of β-sialon sintered bodies with various z values were manufactured, and the relationship between the z value and rolling fatigue life in an environment where hard foreign matter entered inside the rolling bearings was investigated. A test was conducted. The test procedure is as follows.

  First, a method for producing a test bearing to be tested will be described. First, β sialon powder prepared by a combustion synthesis method with a z value in the range of 0.1 to 2.5 was prepared, and the z value was 0.1 to 2.5 in the same manner as in Example 1 above. A rolling element was produced. And the bearing of the JIS standard 6206 model number was produced combining with the bearing ring produced using the various steel materials prepared separately as a raw material (comparative example BF, Examples AE). As steel constituting the race, JIS standards SUJ2, SCM420, SCr420, S53C, S45C, S40C and AISI standard M50 were adopted. For comparison, a rolling element made of silicon nitride, that is, a rolling element having a z value of 0 was also produced in the same manner as the rolling element made of β sialon, and similarly assembled to a bearing (Comparative Example A).

Next, test conditions will be described. For the bearing of JIS standard 6206 model number manufactured as described above, the maximum contact surface pressure P _max : 2.5 GPa, bearing rotation speed: 2000 rpm, lubrication: turbine oil VG68, test temperature: room temperature, lubricating oil A fatigue test was performed in which KHA30 powder (particle size 108 to 180 μm; hard foreign matter) prepared by gas atomization was added at a rate of 0.4 g / L. The vibration of the bearing during operation is monitored by the vibration detection device, and the test is stopped when the bearing is damaged and the vibration of the bearing exceeds a predetermined value. Recorded as the lifetime of. In addition, after the test was stopped, the bearing was disassembled to confirm the damaged state of the bearing.

  Table 2 shows the test results of this example. In Table 2, the life in each example and comparative example is shown in the upper part of each column as a life ratio with the life of Comparative Example A (silicon nitride) as 1 when the material of the bearing ring is SUJ2. Yes. Moreover, the damaged part (bearing ring or ball) of the bearing is described in the lower part of each column.

  Referring to Table 2, Examples A to E of the present invention having a z value of 1.0 or more and 2.0 or less clearly have a longer life than silicon nitride (Comparative Example A). Yes. Here, as shown in Table 2, the damaged part was a track member (track ring) as in the case of silicon nitride, and the damaged form was delamination. On the other hand, in Comparative Examples E to F in which the z value exceeds 2.0 and is outside the scope of the present invention, the life is significantly reduced and the rolling element (ball) is damaged (peeled) first. . That is, in Comparative Example E in which the z value is 2.25, it is considered that the bearing part (ball) made of the β sialon sintered body is damaged by the influence of the hard foreign matter, and the life is significantly reduced. Furthermore, in Comparative Example F in which the z value is 2.5, the rolling elements are separated in a shorter time, and the durability of the rolling bearing is significantly reduced.

  On the other hand, in Comparative Examples B to D where the z value is smaller than 1.0 and is outside the scope of the present invention, the life is reduced to substantially the same level as in Comparative Example A, and the raceway member is damaged (peeled). Preceding. That is, in Comparative Example D having a z value of 0.75, the difference in physical properties from Comparative Example A having a z value of 0 (silicon nitride) is reduced. Therefore, damage caused by hard foreign matter that has entered between the ball made of β sialon sintered body and the race member facing the ball is concentrated on the race member side. It is thought that the lifetime was reduced to the same level as that of Comparative Example A employing the ball.

  Furthermore, with reference to Table 2, even if the z value is within the range of the present invention in which the z value is 1.0 or more and 2.0 or less, when the hardness (surface hardness) of the opposite raceway is less than HV680, There is a tendency for the life to decrease compared to the case where the hardness of the raceway is HV680 or higher. This is because when the hardness of the race is low, damage to the race member side is likely to occur due to hard foreign matter that has entered between the ball made of β sialon sintered body and the race member facing the ball. It is believed that there is.

  As described above, when the z value exceeds 2.0, the bearing part itself made of the β sialon sintered body is likely to be damaged. On the other hand, when the z value is less than 1.0, the contact surface pressure between the mating member is low. It increases, and damage to the mating member is likely to occur. And by making z value into 1.0 or more and 2.0 or less, the balance with the intensity | strength of the raw material which comprises a bearing component, and the reduction of the contact surface pressure of bearing components is ensured. As a result, it was confirmed that the life of the rolling bearing including the bearing component made of the β sialon sintered body is improved in an environment where hard foreign matter enters the inside of the bearing. In particular, when one of the race member and the rolling element is a bearing part made of a β sialon sintered body and the other of the race member and the rolling element is a bearing part made of steel, the physical properties of the race member and the physical properties of the rolling element are In harmony with each other, it is possible to suppress the occurrence of damage due to hard foreign matters. In this way, by setting the z value to 1.0 or more and 2.0 or less, it is possible to stably ensure sufficient durability while being inexpensive, and hard foreign matter is present inside the bearing. It was confirmed that it is possible to provide a rolling bearing provided with a bearing component made of a β sialon sintered body that can be used even in an intruding environment.

  Further, when one of the race member and the rolling element is a bearing part made of β sialon sintered body and the other of the race member and the rolling element is a bearing part made of steel, in order to suppress damage to the bearing part made of steel. It was confirmed that the surface hardness of the bearing parts made of steel is preferably HV680 or more.

  Embodiment 3 of the present invention will be described below. A test was conducted to investigate the formation state of the dense layer and the highly dense layer in the cross section of the bearing component of the present invention. The test procedure is as follows.

First, a β sialon powder (product name: Melamix, manufactured by Isman Jay Co., Ltd.) having a composition of Si ₅ AlON ₇ prepared by a combustion synthesis method is prepared, and the bearing component described in Embodiment 1 with reference to FIG. A cubic test piece having a side of about 10 mm was produced in the same manner as in the manufacturing method. A specific manufacturing method is as follows. First, a β sialon powder refined to submicron, aluminum oxide (manufactured by Sumitomo Chemical Co., Ltd., AKP30) and yttrium oxide (manufactured by HC Starck Co., Ltd., Yttrium oxide grade C) as a ball mill Were mixed by wet mixing. Then, granulation was performed with a spray dryer to produce granulated powder. The granulated powder was molded into a predetermined shape with a mold and further pressed by cold isostatic pressing (CIP) to obtain a molded body. Subsequently, the cube test piece was manufactured by heating and sintering the molded body at 1650 ° C. in a nitrogen atmosphere at a pressure of 0.4 MPa.

  Thereafter, the test piece was cut, and the cut surface was lapped with a diamond lapping machine, and then mirror lapping with a chromium oxide lapping machine was performed to form a cross section for observation including the center of the cube. And the said cross section was observed with the oblique light of the optical microscope (the Nikon Corporation make, Microphoto-FXA), and the 50-times-magnification instant photograph (Fujifilm Corporation FP-100B) was image | photographed. Thereafter, the obtained photographic image was taken into a personal computer using a scanner (resolution: 300 DPI). And the binarization process by a brightness | luminance threshold value was performed using the image processing software (Mitani Corporation WinROOF) (binarization separation threshold value in a present Example: 140), and the area ratio of the white area | region was measured.

  Next, test results will be described. FIG. 10 is a photograph of a cross section for observation of the test piece taken with oblique light from an optical microscope. FIG. 11 is an example showing a state in which the image of the photograph of FIG. 10 is binarized using a luminance threshold using image processing software. FIG. 12 shows a region (evaluation region) where image processing is performed when the image of the photograph of FIG. 10 is binarized by a luminance threshold using image processing software and the area ratio of the white region is measured. FIG. In FIG. 10, the upper side of the photograph is the surface side of the test piece, and the upper end is the surface.

  Referring to FIGS. 10 and 11, the test piece in the present example manufactured by the same manufacturing method as the bearing component of the present invention has a layer with less white area than the inside in the area including the surface. I understand that. Then, as shown in FIG. 12, the photographed photograph image is divided into three regions according to the distance from the outermost surface of the test piece (the region having a distance from the outermost surface of 150 μm or less, the region exceeding 150 μm and within 500 μm, When the area ratio of the white area was calculated by performing image analysis for each area and obtaining the area ratio of the white area, the results shown in Table 3 were obtained. Table 3 shows the average value and the maximum value of the area ratio of the white area in five fields of view obtained from five photographs taken at random with each field shown in FIG. 12 as one field of view. Yes.

  Referring to Table 3, the area ratio of the white region in the present example was 18.5% inside, whereas it was 3.7% in the region having a depth of 500 μm or less from the surface. It was 1.2% in the region where the depth from the region was 150 μm or less. From this, the test piece in the present example produced by the same manufacturing method as the bearing component of the present invention has a dense layer and a highly dense layer with less white area than the inside in the area including the surface. Was confirmed.

  Embodiment 4 of the present invention will be described below. A test was conducted to confirm the rolling fatigue life of the bearing component of the present invention. The test procedure is as follows.

First, a method for producing a test bearing to be tested will be described. First, a β sialon powder (product name: Melamix, manufactured by Isman Jay Co., Ltd.) having a composition of Si ₅ AlON ₇ prepared by a combustion synthesis method is prepared, and the bearing component described in Embodiment 1 with reference to FIG. A 3/8 inch ceramic sphere having a diameter of 9.525 mm was produced in the same manner as the production method described above. A specific manufacturing method is as follows. First, a β sialon powder refined to submicron, aluminum oxide (manufactured by Sumitomo Chemical Co., Ltd., AKP30) and yttrium oxide (manufactured by HC Starck Co., Ltd., Yttrium oxide grade C) as a ball mill Were mixed by wet mixing. Then, granulation was performed with a spray dryer to produce granulated powder. The granulated powder was molded into a sphere with a mold, and further pressurized by cold isostatic pressing (CIP) to obtain a spherical molded body.

  Next, the green body is processed so that the processing allowance after sintering becomes a predetermined dimension, and the green body is subsequently heated to 1650 ° C. in a nitrogen atmosphere at a pressure of 0.4 MPa. By sintering, sintered spheres were produced. Next, lapping was performed on the sintered spheres to obtain 3/8 inch ceramic spheres (rolling elements; JIS grade G5). And the bearing of the JIS standard 6206 model number was produced in combination with the bearing ring made from bearing steel (JIS standard SUJ2) prepared separately. Here, the thickness (processing allowance) of the sintered sphere removed by the lapping process on the sintered sphere was changed in eight stages, and eight types of bearings were produced (Examples A to H). On the other hand, for comparison, lapping is performed on sintered spheres (EC 141 manufactured by Nippon Special Ceramics Co., Ltd.) sintered by pressure sintering using raw material powders composed of silicon nitride and a sintering aid in the same manner as described above. Processing was performed, and a bearing of JIS standard 6206 model number was manufactured in combination with a bearing ring (JIS standard SUJ2) prepared separately (Comparative Example A). The machining allowance for lapping was 0.25 mm.

Next, test conditions will be described. For the bearing of JIS standard 6206 model number produced as described above, maximum contact surface pressure Pmax: 3.2 GPa, bearing rotation speed: 2000 rpm, lubrication: circulating oil supply of turbine oil VG68 (clean oil), test temperature: room temperature, A fatigue test was performed under the conditions of The vibration of the bearing during operation is monitored by the vibration detection device, and the test is stopped when the rolling element is damaged and the vibration of the bearing exceeds a predetermined value. Recorded as bearing life. The number of tests was 15 in each of the examples and the comparative examples, and after calculating the L ₁₀ life, the durability was evaluated by the life ratio with respect to Comparative Example A.

  Table 4 shows the test results of this example. Referring to Table 4, it can be said that the life of the bearings of the examples is all good considering the manufacturing cost and the like. The life of the bearings of Examples D to G in which the dense layer remains on the surface of the rolling element by setting the machining allowance to 0.5 mm or less is about 1.5 to 2 times the life of Comparative Example A. It was. Furthermore, the life of the bearings of Examples A to C in which the high-density layer remained on the surface of the rolling element by setting the machining allowance to 0.15 mm or less was about three times the life of Comparative Example A. From this, it was confirmed that the rolling bearing provided with the bearing component of the present invention is excellent in durability. And the rolling bearing provided with the bearing part of the present invention has a machining cost of the bearing part of 0.5 mm or less, the life is improved by leaving a dense layer on the surface, and the machining cost of the bearing part is 0.15 mm or less. As a result, it was found that the lifetime was further improved by leaving the highly dense layer on the surface.

  The embodiments and examples disclosed herein are illustrative in all respects and should not be construed as being restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  The bearing component and the rolling bearing of the present invention can be particularly advantageously applied to a bearing component made of a sintered body containing β sialon as a main component and a rolling bearing including the bearing component.

FIG. 3 is a schematic cross-sectional view showing the configuration of the deep groove ball bearing in the first embodiment. It is a schematic fragmentary sectional view which expands and shows the principal part of FIG. FIG. 5 is a schematic cross-sectional view showing a configuration of a thrust needle roller bearing in a modification of the first embodiment. FIG. 4 is a schematic partial cross-sectional view showing an enlarged main part of a bearing ring provided in the thrust needle roller bearing of FIG. 3. It is a schematic sectional drawing which expands and shows the needle roller with which the thrust needle roller bearing of FIG. 3 is provided. It is a figure which shows the outline of the manufacturing method of the rolling bearing in Embodiment 1. FIG. It is a figure which shows the outline of the manufacturing method of the bearing components contained in the manufacturing method of the rolling bearing in Embodiment 1. FIG. FIG. 6 is a schematic cross-sectional view showing a configuration of a hub unit that is a rolling bearing in a second embodiment. It is a general | schematic fragmentary sectional view which expands and shows the principal part of FIG. It is the photograph which image | photographed the cross section for observation of a test piece with the oblique light of the optical microscope. It is an example which shows the state which binarized the image of the photograph of FIG. 10 by the brightness | luminance threshold value using image processing software. It is a figure which shows the area | region (evaluation area | region) which performs image processing, when the image of the photograph of FIG. 10 is binarized by a luminance threshold value using image processing software and the area ratio of the white area is measured.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Deep groove ball bearing, 2 Thrust needle roller bearing, 3 Hub unit, 11 Outer ring, 11A Outer ring rolling surface, 11B Outer ring dense layer, 11C, 12C, 13C Inside, 11D Outer ring high dense layer, 12 Inner ring, 12A Inner ring rolling surface , 12B inner ring dense layer, 12D inner ring dense layer, 13 balls, 13A ball rolling surface, 13B ball dense layer, 13D ball dense layer, 14, 24, 39A, 39B cage, 21 race ring, 21A race ring rolling Surface, 21B raceway ring dense layer, 21C, 23C inside, 21D raceway ring dense layer, 23 needle roller, 23A roller rolling surface, 23B roller dense layer, 23D roller dense layer, 31 outer ring, 31A1, 31A2, 32A, 33A Rolling surface, 31B Outer ring dense layer, 31C, 32C, 33C, 34C Inside, 31D Outer ring dense layer, 32 Hub wheel, 32B Ring dense layer, 32D Hub ring dense layer, 33 Inner ring, 33B Inner ring dense layer, 33D Inner ring dense layer, 34 balls, 34A Ball rolling surface, 34B Ball dense layer, 34D Ball dense ring layer, 35 Hub ring flange , 35A hub ring through hole, 36 bolt, 37 outer ring flange, 37A outer ring through hole, 38 fixed ring, 39A, 39B cage.

Claims (9)

In a rolling bearing, a bearing component that is a rolling element disposed on an annular raceway in contact with the raceway member or the raceway member,
Compared to silicon nitride, a bearing component made of ceramics that can suppress damage to the other bearing component when a hard foreign object is caught between the bearing component and the other bearing component. The ceramics are
_{Si 6-Z Al Z O Z} N 8-Z is represented by the composition formula as a main component β-sialon satisfying 1.0 ≦ z ≦ 2.0, constituted by a sintered body made of the balance impurities, wherein Item 1. The bearing component according to Item 1. The ceramics are
From a sintered body comprising a β sialon represented by a composition formula of Si _6-Z Al _Z O _Z N _8-Z and satisfying 1.0 ≦ z ≦ 2.0 as a main component, and the remaining sintering aid and impurities. The bearing component according to claim 1, which is configured.   The bearing component according to claim 2 or 3, wherein a dense layer that is a denser layer than the inside is formed in a region including a rolling surface that is a surface in contact with another bearing component.   The bearing component according to claim 4, wherein when the cross section of the dense layer is observed with oblique light from an optical microscope, the area ratio of the white region observed as a white region is 7% or less.   The bearing component according to claim 4 or 5, wherein a high-density layer, which is a layer having a higher density than other areas in the dense layer, is formed in a region including the surface of the dense layer.   The bearing component according to claim 6, wherein when the cross section of the high-density layer is observed with oblique light from an optical microscope, the area ratio of the white region observed as a white region is 3.5% or less. A track member;
A plurality of rolling elements that are in contact with the raceway member and disposed on an annular raceway,
At least any one of the said track member and the said rolling element is a rolling bearing which is a bearing component of any one of Claims 1-7. One of the race member and the rolling element is a bearing component according to any one of claims 1 to 7,
The other of the race member and the rolling element is a bearing part made of steel,
The rolling bearing according to claim 8, wherein the surface hardness of the bearing part made of steel is HV680 or more.