JP2014095469A - Rolling bearing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rolling bearing capable of maintaining a lubricant film over a long term, suppressing occurrence of sudden temperature rise and burn-in and improving bearing performance by suppressing vibrations upon sliding even when being used for a member which performs high-speed rotation of a spindle of a working machine or the like.SOLUTION: Surface roughness of an inner surface of a pocket and a surface 12a to be guided of a retainer 10 is set as an arithmetic average roughness Ra of 1.0 to 9.8 μm and the maximum height Rt is set as 10.1 to 102.9 μm. Thereby, a lubricant is retained on a recessed part forming the surface roughness, grease is supplied to a contact interface between the surface 12a to be guided of the retainer 10 and a guide surface 2b of an outer ring 2 from the recessed part and, therefore, an oil film can be formed without interruption on the contact interface. Further, the formation of a specifically high mountain part and low valley part is suppressed, vibrations upon the sliding is suppressed and bearing performance can be improved.

Description

  The present invention relates to a rolling bearing.

  Generally, rolling bearings such as cylindrical roller bearings and angular ball bearings are used as bearings for main spindles of machine tools. As the cage for these rolling bearings, a so-called plastic cage (synthetic resin cage) made of a cotton cloth-reinforced phenolic resin or a polyamide 66 resin reinforced with glass fiber is used. It is done. Since the plastic cage is lightweight, it has a small centrifugal force during rotation and is self-lubricating, which is advantageous for high-speed rotation. In rolling bearings for high-speed rotation using these plastic cages, an outer ring guide system in which the cage is rotated and guided by a bearing outer ring is usually employed.

  In addition, as a lubrication method for these rolling bearings, grease lubrication, oil-air lubrication, jet lubrication, etc. are appropriately selected depending on the use conditions and cost, but generally they are low in cost and easy to maintain. Grease-filled lubrication by initial filling is often used.

  Incidentally, in recent years, in the field of machine tools, there is a tendency to improve the cutting ability and shorten the machining time, and accordingly, the tendency to increase the rotation speed of the main spindle is remarkable. For this reason, the amount of lubricating oil supplied to the bearing that supports the main shaft that rotates at high speed also tends to be very small (the minimum amount necessary).

  However, when the lubricating oil is not supplied from the outside to the inside of the bearing during rotation, such as grease lubrication, the lubricating oil film tends to be interrupted due to a temporary or continuous shortage of lubricating oil over time. End up. Under such severe lubrication conditions, it is difficult to obtain sufficient lubrication.

  In the bearing cages described in Patent Documents 1 and 2, the holding force of the base oil in the pocket is improved by roughening the inner surface of the pocket of the holding portion.

JP 2007-198469 A Japanese Patent Laid-Open No. 11-108064

  By the way, in the bearing cage described in Patent Document 1, arithmetic average roughness Ra is used as a parameter of surface roughness. However, as shown in FIG. 11, in the case where the arithmetic average roughness Ra is the same, if the maximum height Rt is large, it is considered that the surface has a specific high peak or low valley relative to the periphery. It is done. If there are specifically high peaks or low valleys (see XI and XI 'in Fig. 11 (b)), it will cause vibration during sliding, which is not preferable for bearing performance and may have an adverse effect on the service life. There is sex. In the bearing cages described in Patent Documents 1 and 2, the point of roughening in consideration of both the arithmetic average roughness Ra and the maximum height Rt is not described.

  Moreover, in the bearing cages described in Patent Documents 1 and 2, only the inner surface of the pocket of the cage is roughened, and it is not assumed to be used in a high speed range like the outer ring guide type rolling bearing described above. It is considered a thing. In bearings in which the cage is guided to the outer ring or inner ring, not only the sliding part between the cage and rolling element, but also the sliding part between the cage and outer ring or inner ring generates heat and becomes hot. There was a case where the problem of being burned down and stopping the rotation occurred.

  The present invention has been made in view of the above-described problems. The purpose of the present invention is to maintain a lubricating oil film over a long period of time, even when used in an apparatus that rotates at high speed, such as a spindle of a machine tool. An object of the present invention is to provide a rolling bearing capable of suppressing the occurrence of excessive temperature rise and seizure, and further suppressing vibration during sliding to improve bearing performance.

The above object of the present invention can be achieved by the following constitution.
(1) an inner ring having an outer peripheral surface on which an inner ring raceway surface is formed;
An outer ring having an inner peripheral surface on which an outer ring raceway surface is formed;
A plurality of rolling elements arranged to be freely rollable between the inner ring raceway surface and the outer ring raceway surface;
A cage having a plurality of pockets for holding the plurality of rolling elements in a rollable manner and a guided surface guided by the inner ring or the outer ring;
A rolling bearing with
The cage is a synthetic resin cage,
As for the surface roughness of at least one of the inner surface of the pocket with which the rolling element abuts and the guided surface, the arithmetic average roughness Ra is 1.0 to 9.8 μm, and the maximum height Rt is 10.1. A rolling bearing characterized by having a thickness of -102.9 μm.
(2) The surface roughness of at least one of the inner surface of the pocket with which the rolling element abuts and the guided surface is characterized in that the average interval RSm of unevenness is 29.3 to 213.2 μm ( Rolling bearing according to 1).
(3) The surface roughness of at least one of the inner surface of the pocket with which the rolling element abuts and the guided surface is such that the inner diameter of the pocket is R (mm) and the diameter of the rolling element is r (mm). , T = (R × r) / 2 (R−r), 2.33 × 10 ⁻⁶ ≦ Ra / T (m / m) ≦ 6.33 × 10 ⁻⁴ The rolling bearing according to (1) or (2).

According to the rolling bearing of the present invention, the arithmetic average roughness of at least one of the inner surface of the pocket with which the rolling element of the cage abuts and the guided surface is set to 1.0 to 9.8 μm. Lubricating oil is held in the recess that forms the roughness, and lubricant is supplied from this recess to the contact interface between the pocket inner surface and the surface of the rolling element and the contact interface between the cage and the inner ring or outer ring. It is possible to form the oil film without interruption.
As a result, even when the lubrication conditions become severe due to high-speed rotation, the oil film is formed without interruption at the contact interface, so that rapid temperature rise and seizure can be suppressed for a longer time than before. Is possible.
Furthermore, since the maximum height Rt of the surface satisfying the above-mentioned arithmetic mean roughness Ra is set to 10.1 to 102.9 μm, the occurrence of specifically high peaks and low valleys is suppressed, Vibration can be suppressed and bearing performance can be improved.

It is principal part sectional drawing of the angular ball bearing which concerns on embodiment of this invention. It is sectional drawing which shows the spindle apparatus as a bearing testing machine. It is a figure which shows the cross-sectional shape of the to-be-guided surface of a holder | retainer. It is a figure for demonstrating the average space | interval RSm of an unevenness | corrugation. It is a figure for demonstrating skewness. It is a figure for demonstrating dimensionless surface roughness using the equivalent radius T. FIG. It is a graph explaining the relationship between arithmetic mean roughness Ra and image sticking life ratio. It is a graph explaining the relationship between the maximum height Rt and the seizure life ratio. It is a graph for demonstrating the relationship between the average space | interval RSm of an unevenness | corrugation, and a seizing lifetime ratio. It is a graph for demonstrating the relationship between Ra / T and a seizure lifetime ratio. It is a figure for demonstrating the maximum height Rt.

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

  An angular ball bearing 1 as a rolling bearing of the present embodiment is used in a device that rotates at high speed, such as a spindle of a machine tool, and an outer ring 2 having an outer ring raceway surface 2a on an inner peripheral surface and an inner ring raceway surface 3a on an outer peripheral surface. A plurality of balls (rolling elements) 4 that are arranged to freely roll with a contact angle α between the inner ring 3 and the outer ring raceway surface 2a and the inner ring raceway surface 3a, and a plurality of balls 4 in the circumferential direction. Are respectively disposed so as to close the axial opening at both ends of the bearing space existing between the inner circumferential surface of the outer ring 2 and the outer circumferential surface of the inner ring 3, and seal the interior of the bearing. A pair of oil seals 5. In this embodiment, the angular ball bearing 1 is used in grease-filled lubrication that is lubricated by the grease initially sealed in the bearing space.

  The cage 10 is formed at a predetermined interval in the circumferential direction, and has a plurality of cylindrical pockets 11 that hold the balls 4 respectively. Further, in the cage 10, the guided surface 12 a (outer peripheral surface) of one (right side in FIG. 1) of the pair of ring portions 12 positioned on both sides in the axial direction is the outer ring raceway surface of the outer ring 2. This is an outer ring guide system that is guided by the guide surface 2b (inner peripheral surface) on the counter-bore side with respect to 2a.

  Here, the cage 10 is formed by injection molding using a synthetic resin such as polyamide, PPS (polyphenylene sulfide), PEEK (polyetheretherketone) or the like as a main material. Larger surface roughness than usual is transferred to the inner surface 11a of the pocket 11 and the guided surface 12a of the ring portion 12 that are in contact with each other. Here, the surface roughness is not machined but is provided by a mold during injection molding because the material becomes high temperature during injection molding so that the surface of the inner surface 11a of the pocket 11 and the guided surface 12a. This is because a surface layer is formed on the surface, thereby improving the wear resistance. A similar effect can be expected by a method of imparting surface roughness to the inner surface 11a and guided surface 12a of the pocket 11 with which the balls 4 abut by shot processing. In this case, in order to eliminate the influence of residual media, Shot processing using stainless media is desirable.

  Specifically, the surface roughness imparted to the inner surface 11a of the pocket 11 of the cage 10 and the guided surface 12a is such that the arithmetic average roughness Ra specified in JIS B0601 is 1.0 to 9.8 μm, the maximum height. The thickness Rt is set to 10.1-102.9 μm. As a result, the grease is held in the concave portion forming the surface roughness, and the contact interface between the inner surface 11a of the pocket 11 of the cage 10 and the surface of the ball 4 and the guided surface 12a of the cage 10 and the outer ring 2 from the concave portion. Since grease is supplied to the contact interface with the guide surface 2b, an oil film can be formed on the contact interface without interruption.

  As a result, even when the lubrication conditions become severe due to high-speed rotation, the oil film is formed without interruption at the contact interface, so that rapid temperature rise and seizure are suppressed for a longer time than before. Is possible.

  The cage 10 may be reinforced with a filler such as glass fiber or carbon fiber in order to improve wear resistance and mechanical strength, but the inner surface 11a of the pocket 11 of the cage 10 and the ball 4 and the wear powder containing the filler generated at the contact interface between the guided surface 12a of the cage 10 and the guide surface 2b of the outer ring 2 may act as a foreign substance, and cutting wear may increase. There is. However, in the present embodiment, the wear powder is caused to contact the contact interface by the surface roughness that exists in parallel with the direction in which the cage 10 and the rolling element are guided, that is, the unevenness formed along the circumferential direction and the rotating direction of the rolling element. Therefore, it is possible to improve wear resistance. In addition, the surface roughness and irregularities in the direction perpendicular to the guided direction are also preferably within the scope of the present invention, since the wear resistance is further improved.

  In the range where the arithmetic average roughness Ra is less than 1.0 μm, the amount of grease retained in the recesses forming the surface roughness decreases, and the contact interface between the inner surface 11a of the pocket 11 of the cage 10 and the surface of the ball 4; In addition, the supply of grease to the contact interface between the guided surface 12a of the cage 10 and the guide surface 2b of the outer ring 2 becomes insufficient. Further, when the arithmetic average roughness Ra exceeds 9.8 μm, the roughness itself may adversely affect the rotation accuracy of the spindle bearing for machine tools that require high-precision and high-speed rotation.

  Further, the surface roughness applied to the inner surface 11a of the pocket 11 with which the ball 4 abuts and the guided surface 12a of the ring portion 12 has a maximum height Rt of 10.1 to 102.9 μm. By defining the maximum height Rt in this way, it is possible to suppress the generation of specifically high peaks and low valleys, suppress vibration during sliding, and improve bearing performance.

  Furthermore, it is preferable that the surface roughness given to the inner surface 11a of the pocket 11 with which the ball 4 abuts and the guided surface 12a of the ring portion 12 has an average interval RSm of 29.3 to 213.2 μm. This is because, when the arithmetic average roughness Ra is the same, the surface having a large average irregularity interval RSm has a shape with a small number of irregularities and a large width of each irregularity, as shown in FIG. Conceivable. If it has such a shape, it may occur that the rolling element falls into the recesses of the provided unevenness (see IV in FIG. 4B), which may cause vibration and breakage. In addition, when the average interval RSm of the unevenness is out of the range of the present invention, there is a moment when there is no recess that becomes a sump in the contact area, and the effect of improving seizure resistance by providing the unevenness is maximized. It becomes difficult to draw out to the limit. For this reason, it is desirable to set to RSm within the specified range.

Further, the inner surface 11a of the pocket 11 with which the ball 4 abuts and the guided surface 12a of the ring portion 12 have a skewness RSk defined by JIS B0601: 2001 of 2 or less, preferably 0 or less. It is preferable for reducing the size and extending the life.
As described above, it is important that the retainer surface has a large number of recesses for promoting the supply of lubricant and the discharge of wear powder, and the inner surface 11a of the pocket 11 and the guided surface 12a are sharp. The smaller the number of convex parts (pointed), the better. The skewness RSk is a parameter representing a surface shape called a skewness. If the skewness RSk is 0 or less (or negative), as shown in FIG. 5B, the cross-sectional shape of the surface is a slow curved shape. It is preferable that the convex portions are continuously present. On the other hand, when the skewness RSk is positive, as shown in FIG. 5A, the cross-sectional shape of the surface has a state in which sharp (pointed) convex portions continuously exist, which adversely affects the vibration and life of the bearing. May affect. For this reason, the shape to be imparted to the cage surface must be at most 2 or less in skewness RSk, and is desirably negative when a higher effect is expected. This is because if the skewness RSk is 2 or less, it is expected that the protruding protrusion on the surface is removed and the skewness RSk is reduced due to a phenomenon called wear or familiarity that occurs in the initial stage of operation.

Further, as the balls 4, ceramic balls are preferably used.
Ceramic balls such as silicon nitride have features such as light weight, high rigidity, low thermal expansion, low friction, and low heat generation, and are particularly effective in improving seizure resistance when the bearing is used at a high speed. Further, when used together with the cage 10 having the surface shape as in the present invention, a higher seizure resistance improving effect can be expected due to a synergistic effect. This is because the ceramic balls are hard, so that when the same load is applied, the amount of deformation of the resin increases, and the lubricant stored in the recesses is supplied more efficiently.

  In addition, it is preferable from the viewpoint of bearing life that the surface roughness of the balls 4 is Ra ≦ 0.05 μm, and the surface roughness of the guide surface 2b of the outer ring 2 is Ra ≦ 1.0 μm. This is because the bearing steel is harder than the cage 10, and if the surface of the ball 4 or the guide surface 2 b is rough, the wear of the cage 10 is promoted and the applied surface shape may be worn away at an early stage. Because there is. Therefore, it is desirable that the lubricant supply and the wear powder trap effect are caused by the unevenness of the cage surface, and that the balls 4 and the guide surface 2b are within the specified range so as not to wear the cage 10.

As described above, according to the angular ball bearing 1 of the present embodiment, the surface roughness of the inner surface 11a of the pocket 11 with which the ball 4 of the cage 10 abuts and the guided surface 12a of the ring portion 12 are arithmetic averages. The roughness Ra is set to 1.0 to 9.8 μm. As a result, the lubricating oil is held in the concave portion forming the surface roughness, and the contact interface between the inner surface 11a of the pocket 11 and the surface of the ball 4 from the concave portion, the guided surface 12a of the cage 10 and the guide surface of the outer ring 2 Since grease is supplied to the contact interface with 2b, it is possible to form an oil film on the contact interface without interruption. As a result, even when the lubrication conditions become severe due to high-speed rotation, the oil film is formed without interruption at the contact interface, so that rapid temperature rise and seizure are suppressed for a longer period than before. Is possible.
Further, even when the cage 10 is reinforced with a filler such as glass fiber or carbon fiber in order to improve wear resistance and mechanical strength, the direction in which the cage 10 and the rolling element are guided. The surface roughness that exists in parallel with the surface can easily remove the abrasion powder from the contact interface and improve the wear resistance.
Furthermore, since the maximum height Rt of the surface satisfying the above-mentioned arithmetic mean roughness Ra is set to 10.1 to 102.9 μm, the occurrence of specifically high peaks and low valleys is suppressed, Vibration can be suppressed and bearing performance can be improved.

  Moreover, since the surface roughness of the guided surface 12a of the cage 10 is such that the average interval RSm of the unevenness is 29.3 to 213.2 μm, the size of the unevenness width is appropriately set, and the seizure resistance is further improved. It is possible to improve. In addition, the surface roughness and irregularities in the direction perpendicular to the guided direction are also preferably within the scope of the present invention, since the wear resistance is further improved.

  Further, the surface roughness of the guided surface 12a of the cage 10 and the inner surface 11a of the pocket 11 is given by transfer from a mold at the time of injection molding of the cage 10 or by shot processing using a stainless medium. A surface layer is formed on the guide surface 12a and the inner surface 11a, and wear resistance can be improved.

  In the above-described embodiment, the surface roughness of the inner surface 11a of the pocket 11 with which the ball 4 abuts and the guided surface 12a of the ring portion 12 are defined, but this is applied when defining parameters such as the surface roughness. The optimum value varies depending on the size, name and usage conditions of the bearing. For example, when a surface shape is imparted to the cage 10 of a small bearing, the pocket inner diameter of the rolling element and the cage 10 is naturally reduced, and accordingly, the contact area between the rolling element and the pocket surface is also reduced. At this time, the arithmetic average roughness Ra, the maximum height Rt, and the average interval RSm of the unevenness that define the surface roughness necessary for exhibiting the effect are reduced. This is because if the unevenness in the applied surface roughness is extremely large with respect to the contact area, the rolling element may fall into the recesses in the provided unevenness, which may cause vibration and breakage. Further, when a surface shape is imparted to the cage 10 of the large bearing, the arithmetic average roughness Ra, the maximum height Rt, and the average interval RSm for defining the surface roughness required to express the effect accordingly are accordingly determined. Will grow. Because, as the bearing size increases, the load applied to the cage surface also tends to increase, so if the surface roughness applied is too small, the shape applied during use will be worn and worn away. This is because there is a possibility that a problem such as unsatisfactory durability can occur. Therefore, in order to sufficiently exert the effect of the surface shape with the bearings of the respective sizes, the arithmetic average roughness Ra, the maximum height Rt, the average interval RSm of the irregularities, the diameter r of the rolling element and the cage By making dimensionless by the value of equivalent radius T obtained from the relationship of 10 pocket inner diameters R, the technology can be applied to bearing cages of any size.

  That is, as shown in FIG. 6, when the contact between two curved surfaces is replaced with the contact between one curved surface and one flat surface, the radius of the replaced one curved surface is called an equivalent radius T, and the curved surface is inscribed. In this case, if the radius of the inner curved surface is q and the radius of the outer curved surface is Q, T = (Q × q) / (Q−q). It is theoretically derived that the contact area when two curved surfaces come into contact is greatly influenced by the equivalent radius.

When this idea is applied to the relationship between the pocket surface of the cage 10 and the rolling element, in the present invention, when the pocket surface inner diameter of the cage 10 is R and the diameter of the rolling element is r,
Q = R / 2, q = r / 2
Is equivalent to
Substituting Q and q into T = (Q × q) / (Q−q),
T = ((R / 2) × (r / 2)) / (R / 2−r / 2)
T = (R × r) / 2 (R−r).

In addition, when the surface roughness and dimples are applied to the surface, the size of the contact area affects the presence or absence of the effect and the size, and when the contact area is large, a large surface roughness should be applied, By newly finding that a small surface roughness should be imparted when the contact area is small, the surface roughness Ra is divided by the equivalent radius T and rendered non-dimensional as Ra / T. The value can be used for a cage of a large size.
Further, similarly to the above, the maximum height Rt and the average interval RSm of unevenness were also made dimensionless as Tt / T and RSm / T using T.

Specifically, Ra / T is 2.33 × 10 ⁻⁶ ≦ Ra / T (m / m) ≦ 6.33 × 10 ⁻⁴ , preferably 2.33 × 10 ⁻⁶ ≦ Ra / T (m /M)≦4.21×10 ⁻⁴ , thereby improving seizure resistance. Rt / T is 4.67 × 10 ⁻⁵ ≦ Rt / T (m / m) ≦ 5.47 × 10 ⁻³ , preferably 4.67 × 10 ⁻⁵ ≦ Rt / T (m / m ) ≦ 4.21 × 10 ⁻³ and RSm / T is 1.40 × 10 ⁻⁴ ≦ RSm / T (m / m) ≦ 8.79 × 10 ⁻³ , preferably 1.40 × 10 ⁻⁴ ≦ RSm / T (m / m) ≦ 8.41 × 10 ⁻³ is set. When these regulations are satisfied, seizure resistance can be further improved. For dimensionlessness, parameters such as Ra, Rt, and RSm, and the units of the pocket surface inner diameter R, the rolling element diameter r, and the equivalent radius T are aligned.

  In addition, this invention is not limited to each embodiment mentioned above, A deformation | transformation, improvement, etc. are possible suitably.

  For example, in the above-described embodiment, the outer ring guide method in which the cage 10 is guided to the outer ring 2 is described, but an inner ring guide method may be used. In this case, the surface roughness of the guided surface (inner peripheral surface) of the cage guided by the guide surface (outer peripheral surface) of the inner ring has at least an arithmetic average roughness Ra of 1.0 to 9.8 μm and a maximum height. The thickness Rt is set to 10.1 to 102.9 μm, and preferably the average interval RSm of the unevenness is set to 29.3 to 213.2 μm. With this configuration, the oil film is formed without interruption at the contact interface between the guided surface of the cage and the guide surface of the inner ring, and wear powder is easily discharged from the contact interface. Can be suppressed over a longer period of time than before.

  Further, as long as the surface roughness of the present invention is applied to at least the guided surface of the cage 10, the surface roughness may be imparted to the outer peripheral surface or the entire inner peripheral surface of the cage 10. Surface roughness may be imparted to the entire surface.

  Further, in the above-described embodiment, the surface roughness is given to the inner surface 11a with which the balls 4 abut out of the pockets 11 of the cage 10, but the surface roughness is given to the entire surface of the pocket 11 of the cage 10. It doesn't matter.

  Further, the rolling bearing is not limited to the angular ball bearing, and may be any rolling bearing such as a cylindrical roller bearing.

Example 1
Next, the outer ring guide type angular contact ball bearing 1 (model number: 70BNR20HTV1V) as shown in FIG. 1 was incorporated in the spindle device 20 as a bearing tester as shown in FIG.

  The spindle device 20 is a spindle device for machine tools, and a rotary shaft 21 has two rows of angular ball bearings 1 and 1 (front bearings) that support the tool side (front in the axial direction, left side in FIG. 2); The housing H is rotatably supported by two rows of rear bearings 60 and 60 that support the side opposite to the tool (back in the axial direction, right side in FIG. 2). The housing H includes a front lid 31, an outer cylinder 33, and a rear lid 34 in order from the tool side. A tool mounting hole 24 formed in the axial direction through the axis center is provided on the tool side of the rotating shaft 21, and the tool mounting hole 24 is used for mounting a tool (not shown) such as a cutting tool to the rotating shaft 21. used.

Then, the endurance test of the angular ball bearing 1 was performed by rotationally driving the rotating shaft 21 at a rotational speed of 16000 min ⁻¹ (dmn value: 1.42 million) by a motor (not shown). The amount of grease sealed in each angular ball bearing 1 was set to 2.6 g, and the outer cylinder 33 constituting the housing H was cooled by a cooling mechanism (not shown) during the durability test.

  Here, as shown in Table 1, a cage 10 made of PPS formed by injection molding, in which the surface roughness of the inner surface 11a of the pocket 11 and the guided surface 12a are different, is applied to the angular ball bearing 1. The durability test was conducted. The surface roughness of the inner surface 11a of the pocket 11 and the guided surface 12a is such that, in the examples and comparative examples 1-2 and 1-3, random irregularities are formed on the surface of the mold during injection molding by shot peening. When the cage is manufactured by injection molding, the surface shape of the mold is transferred to the surface of the cage. The cage 10 of Comparative Example 1-1 is made of PPS formed by injection molding in which no treatment is applied to the inner surface 11a and the guided surface 12a of the pocket 11.

  Table 1 and FIGS. 7 to 9 show the results of determining the seizure life by measuring the temperature of the outer ring 2, and the seizure life of Comparative Example 1-1 was expressed as 1. In Examples 1-1 to 1-9 in which the arithmetic average roughness Ra of the inner surface 11a of the pocket 11 and the guided surface 12a is set in the range of 1.0 to 9.8 μm, Comparative Examples 1-1 to 1-1 It can be seen that the seizure life is improved as compared with -3. This is because, even after the endurance test, the concave portions constituting the surface roughness remain on the inner surface 11a and the guided surface 12a of the pocket 11, and the grease is easily held, and the inner surface 11a and the ball 4 of the pocket 11 and the holding are retained. This is considered to be due to the effect of assisting lubrication between the guided surface 12a of the vessel 10 and the guide surface 2b of the outer ring 2. If the arithmetic average roughness Ra satisfies the above range, the maximum height Rt is in the range of 10.1 to 102.9 μm, and the average interval RSm of the unevenness is in the range of 29.3 to 213.2 μm, the higher It became clear that a durable life could be obtained. As an example, FIG. 3 shows a cross-sectional shape of the guided surface 12a according to Example 1-2.

(Example 2)
In the second embodiment, as in the first embodiment, an outer ring guide type angular ball bearing 1 (model number: 70BNR20HTV1V) as shown in FIG. 1 is incorporated in a spindle device 20 as a bearing tester as shown in FIG. The seizure life was evaluated. However, in Example 2, as shown in Table 2, the inner surface 11a of the pocket 11 and the guided surface 12a (outer peripheral surface) have different surface roughnesses, and the cage 10 made of PPS formed by injection molding is used. Applied and tested for durability. In addition, the surface roughness of the mold surface during injection molding is given random irregularities by shot peening, and when the cage is manufactured by injection molding, the surface shape of the mold is the surface of the cage. Is transcribed. Here, the cage of Comparative Example 2-1 is made of PPS formed by injection molding in which no treatment is applied to the pocket surface and the guided surface 12a. Other test conditions are the same as in Example 1.

  Table 2 shows the result of determining the seizure life by measuring the temperature of the outer ring 2, and Comparative Example 2-1 was represented as 1. As can be seen from Table 2, the seizure life is improved in any of Examples 2-1 to 2-3, and it can be said that there is an effect of preventing seizure. In the embodiment, the recess remains on the surface even after the test is completed, and the grease is easily held, and between the inner surface 11 a and the ball 4 of the cage pocket 11 and between the guided surface 12 a and the guide surface 2 b of the outer ring 2. It is thought that there was an effect to help lubricate. Further, the surface shape imparting portion may be the inner surface 11a of the pocket 11 or the guided surface 12a that slides with the guide surface 2b of the ball 4 or the outer ring 2, but is preferably imparted to the guided surface 12a. It is more preferable to apply to the inner surface 11a of the pocket 11, and it is still more preferable to apply to both.

(Example 3)
Further, in the third embodiment, as in the first embodiment, the outer ring guide type angular ball bearing 1 as shown in FIG. 1 is incorporated in the spindle device 20 as a bearing tester as shown in FIG. Evaluated. However, in Example 3, as shown in Table 3, the surface roughness of the inner surface 11a of the pocket 11 of the cage 10 and the equivalent radius T are different from each other, and the cage 10 made of PPS formed by injection molding is applied. A durability test was conducted. The cage 10 has a pocket 11 with an inner diameter R of 3.58 to 26.21 mm, and the ball 4 has a diameter r of 3.18 to 25.5 mm. Further, the surface roughness of the inner surface 11a of the pocket 11 is an arithmetic average roughness Ra of 1.0 to 9.8 μm, a maximum height Rt of 10.1 to 102.9 μm, and an average interval RSm of unevenness of 29.3 to 39.3. Those in the range of 213.2 μm are used. Note that, as in Example 1, the surface roughness of the pocket surface is obtained by transferring the surface roughness imparted to the mold by shot peening to the surface of the cage. Further, the cage 10 of Comparative Example 3-1 is made of PPS formed by injection molding in which no treatment is performed on the pocket surface. Further, the cage 10 of Comparative Example 3-2 is made of PPS formed by injection molding, and is transferred from a mold at the time of injection molding. Other test conditions are the same as in Example 1.

Tables 3 to 5 and FIG. 10 show the results of determining the seizure life by measuring the temperature of the outer ring 2, both of which have a life ratio of 1 in Comparative Example 3-1 using an untreated cage. Expressed as: As can be seen from Examples 3-1 to 3-11 shown in Table 3 and FIG. 10, when 2.33 × 10 ⁻⁶ ≦ Ra / T (m / m) ≦ 6.33 × 10 ⁻⁴ , anti-fire resistance The effect of improving adherence can be expected. Preferably, by setting 2.33 × 10 ⁻⁶ ≦ Ra / T (m / m) ≦ 4.21 × 10 ⁻⁴ , the life ratio becomes twice or more that of Comparative Example 3-1. The effect of improving seizure resistance can be expected more.

Table 4 shows Examples 3-12 to 3-21 that satisfy the above range of Ra / T, and 4.67 × 10 ⁻⁵ ≦ Rt / T (m / m) ≦ 5.47 × 10 ^−3. In this case, the effect of improving seizure resistance can be expected. Preferably, 4.67 × 10 ⁻⁵ ≦ Rt / T (m / m) ≦ 4.21 × 10 ⁻³ is set so that the life ratio becomes 5 times or more that of Comparative Example 3-1. The effect of improving seizure resistance can be expected more.

Table 5 shows Examples 3-22 to 3-29 that satisfy the above ranges of Ra / T and Rt / T, and 1.40 × 10 ⁻⁴ ≦ RSm / T (m / m) ≦ 8. When it is 79 × 10 ⁻³ , an effect of improving seizure resistance can be expected. Preferably, by setting 1.40 × 10 ⁻⁴ ≦ RSm / T (m / m) ≦ 8.41 × 10 ⁻³ , the life ratio becomes 5 times or more as compared with Comparative Example 3-1. The effect of improving seizure resistance can be expected more.

(Example 4)
Further, in the same test as in Example 3, the results when a ceramic sphere is used as the ball 4 and when a SUJ2 sphere is used are shown. The cage 10 is the same size, and has not been processed (Comparative Examples 4-1 and 4-2), and has been processed to have the same surface shape as Example 3 (Ra / T, Rt of Example 3). Examples 4-1 and 4-2) that are within the specified ranges of / T and RSm / T were used. In addition, the life ratio in the case of Comparative Example 4-1 in which the cage 10 is untreated and the balls 4 are SUJ2 balls is set to 1.
Therefore, as shown in Table 6, it can be seen that the use of ceramic spheres increases the effect of improving the seizure life of the cage 10 and extends the life.

(Example 5)
Table 7 shows the results of testing the effect of skewness RSk defined in JIS B0601: 2001 in the same experiment as in Example 3. The cages 10 having the same size and within the specified ranges of Ra, Rt, and RSm described above were used as Examples 5-1 to 5-6. Moreover, as Comparative Example 5-1, the life ratio when the retainer 10 is untreated is set to 1.
Therefore, as shown in Table 7, it can be seen that a higher effect can be expected by setting the skewness within the range of -2.0 to 1.9.

(Example 6)
In addition, Table 8 shows the results of testing the effects of rolling element roughness and guide surface roughness in the same experiment as in Example 3. The cage 10 has the same size and is processed so as to have the same shape within the specified ranges of Ra, Rt, and RSm described above. The rolling element roughness Ra and the guide surface roughness shown in Table 8 are used. Durability tests were performed on Examples 6-1 to 6-34 using rolling elements and outer rings having different Ras. Moreover, as Comparative Example 6-1, the life ratio when the cage was not processed was set to 1.
Therefore, as shown in Table 8, it can be seen that a higher effect can be expected by setting the rolling element roughness Ra to 0.05 μm or less and the guide surface roughness Ra to 1.0 μm or less.

1 Angular contact ball bearings (rolling bearings)
2 Outer ring 2a Outer ring raceway surface 2b Guide surface 3 Inner ring 3a Inner ring raceway surface 4 Ball (rolling element)
5 Oil seal 10 Cage 11 Pocket 11a Inner surface 12 Ring portion 12a Guided surface 20 Spindle device 21 Rotating shaft 24 Tool mounting hole 31 Front cover 33 Outer cylinder 34 Rear cover 60 Rear bearing H Housing α Contact angle

Claims (3)

An inner ring having an outer peripheral surface on which an inner ring raceway surface is formed;
An outer ring having an inner peripheral surface on which an outer ring raceway surface is formed;
A plurality of rolling elements arranged to be freely rollable between the inner ring raceway surface and the outer ring raceway surface;
A cage having a plurality of pockets for holding the plurality of rolling elements in a rollable manner and a guided surface guided by the inner ring or the outer ring;
A rolling bearing with
The cage is a synthetic resin cage,
As for the surface roughness of at least one of the inner surface of the pocket with which the rolling element abuts and the guided surface, the arithmetic average roughness Ra is 1.0 to 9.8 μm, and the maximum height Rt is 10.1. A rolling bearing characterized by having a thickness of -102.9 μm.   The surface roughness of at least one of the inner surface of the pocket with which the rolling element abuts and the guided surface has an average interval RSm of 29.3 to 213.2 μm. The rolling bearing described. The surface roughness of at least one of the inner surface of the pocket with which the rolling element abuts and the guided surface is such that the inner diameter of the pocket is R (mm), the diameter of the rolling element is r (mm), and T = 2. It is 2.33 × 10 ⁻⁶ ≦ Ra / T (m / m) ≦ 6.33 × 10 ⁻⁴ when (R × r) / 2 (R−r). Or the rolling bearing of 2.

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