WO2005061914A1

WO2005061914A1 - Rolling bearing

Info

Publication number: WO2005061914A1
Application number: PCT/JP2004/018607
Authority: WO
Inventors: Yoshinobu Akamatsu; Kenji Fujii; Masatsugu Mori
Original assignee: Ntn Corporation
Priority date: 2003-12-22
Filing date: 2004-12-14
Publication date: 2005-07-07
Also published as: JP2005180629A

Abstract

A rolling bearing capable of achieving high-speed, long life, and maintenance-free characteristics by only a grease sealed in the bearing. A rolling bearing has an inner ring (1), an outer ring (2), and rolling bodies (3) interposed between raceway surfaces (1a, 2a) of the inner and outer rings (1, 2). A grease pool forming part (6) and a gap forming piece (7) are provided in the rolling bearing. Inside the grease pool forming part (6) is formed a grease pool (8), and the grease pool forming part (6) is in contact with the outer ring (2). The gap forming piece (7) is a part communicated from the grease pool (8)to near the outer ring raceway surface (2a) to form a gap (14) along an outer ring inner diameter surface (2b). The volume of the gap (14) is such that it can supply a base oil of a grease in the grease pool (8) to near the outer ring raceway surface (2a) by a capillary phenomenon of a thickener

Description

Specification

Rolling bearing

Technical field

The present invention relates to a rolling bearing with a lubrication mechanism for grease lubrication of a machine tool spindle or the like.

^ Scenic technology

[0002] As lubrication methods for machine tool spindle bearings, grease lubrication that can be used without maintenance, air oil lubrication in which lubricating oil is mixed into the carrier air and oil is injected into the bearing from the nozzle, and lubricating oil in the bearing There is a method such as jet lubrication for directly injecting. In recent years, machine tools have tended to operate at higher speeds in order to increase machining efficiency, and air-oil lubrication, in which the lubrication of the main shaft bearings is relatively inexpensive and which can easily be operated at higher speeds, is often used. However, this air oil lubrication method has problems from the viewpoint of cost, noise, energy saving and resource saving, because it requires an air oil supply device as ancillary equipment and a large amount of air. There is also a problem that the environment is deteriorated due to the scattering of oil. In order to avoid these problems, attention has recently been given to speeding up with grease lubrication, and requests have been increasing.

[0003] Since grease lubrication is performed only with grease sealed during bearing assembly, high-speed operation may lead to premature seizure due to deterioration of the grease due to heat generation of the bearing and oil film breakage on the raceway surface, especially on the inner ring. Can be considered. In particular, it is difficult to guarantee the grease life in a high-speed rotation region where the dn value exceeds one million (bearing inner diameter mm X rotation speed 卬 m).

[0004] As a means of extending the grease life, a new proposal has been introduced. One proposal is to provide a grease reservoir on the outer raceway surface to achieve high speed and long life (Japanese Patent Application Laid-Open No. H11-108068). There is also a proposal (Japanese Patent Application Laid-Open No. 2000-113998) that lubrication is performed by appropriately lubricating the bearing portion using a grease reinforcing device provided outside the spindle.

[0005] However, the technologies of the above proposed examples are not satisfactory in consideration of the number of rotations used (> dn value 150,000) equivalent to air-oil lubrication and maintenance-free. Disclosure of the invention

[0006] An object of the present invention is to solve these problems, and to provide a rolling bearing that can achieve high speed, long life, and maintenance-free by using only grease sealed in the bearing. Is what you do.

[0007] A rolling bearing according to the present invention is a rolling bearing having an inner ring, an outer ring, and a plurality of rolling elements interposed between raceway surfaces of the inner and outer rings. The grease reservoir forming part provided in contact with the wheel and forming a grease reservoir therein, and the gap provided on the fixed-side raceway and communicating from the grease reservoir to the vicinity of the raceway surface of the fixed-side raceway ring, And a gap forming piece formed along the peripheral surface on which the raceway surface is formed. The gap has such a small gap that the base oil of the grease in the grease reservoir can be supplied to the vicinity of the raceway surface of the fixed raceway by capillary action of the thickener. It is preferable that the distal ends of the gap forming pieces have a close interval so as not to contact the rolling elements. The gap forming piece is, for example, formed integrally with the grease reservoir forming component. The above grease is a gel or semi-solid at room temperature.

[0008] The rolling bearing having this configuration is used by filling grease into the entire circumference of a grease reservoir and a gap formed between the grease reservoir forming component and the peripheral surface of the raceway surface of the fixed-side bearing ring. Is done. Grease is sealed inside the bearing as initial lubricating oil. As a result, the grease reservoir is connected to the rolling element contact portion on the raceway surface of the fixed raceway by grease. When the grease is connected in this way, the base oil permeates and moves due to the capillary action of the thickener in the grease. For this reason, the base oil consumed as lubricating oil at the rolling element contact portion is continuously supplied to the rolling element contact portion from the grease reservoir through the gap. As a result, the lubrication life of the bearing is determined by the amount of grease in the grease pool, and by appropriately designing the capacity of the grease pool, it is possible to use only the grease sealed in the bearing and maintain it in a maintenance-free manner. High-speed operation and long life are achieved.

In addition, if the above-mentioned gap forming piece is provided facing the rotating raceway, the supply of grease may be excessive due to centrifugal force due to rotation, which may cause a temperature rise. When the gap forming piece is provided in this way, the hair Grease base oil is supplied by capillary action, and lubricated with a small amount of lubricating oil. Therefore, the temperature rise at which the stirring resistance is reduced becomes stable.

The gap forming piece does not necessarily need to be provided on the entire circumference, but by continuously providing it on the entire circumference, the base oil can be supplied to the raceway surface of the fixed side bearing ring from the entire circumference by the above-mentioned capillary phenomenon, and lubricity is improved. Can be excellent. If the grease reservoir is provided continuously over the entire circumference, the supply of base oil supply will be excellent.

[0009] In the present invention, the fixed side race may be an outer race. In that case, the grease reservoir forming part is provided in contact with the outer ring, and the gap forming piece is also provided on the outer ring, and the gap between the gap forming piece and the inner surface of the outer ring communicates from the grease reservoir to the vicinity of the outer ring raceway surface. A gap is formed.

In the case where the gap forming piece is provided on the outer ring side as described above, if the bearing is rotated with the grease sealed therein, the grease sealed inside the bearing is scattered toward the inner diameter portion of the outer ring by centrifugal force. The portion accumulates at the tip of the gap forming piece. As a result, the connection of the grease between the grease pool and the rolling element contact portion on the outer raceway surface is ensured.

[0010] In the present invention, the rolling bearing may be an angular ball bearing, the fixed-side race may be an outer race, and the grease reservoir forming component may be provided on an inner diameter surface of the outer race. The grease reservoir forming component is preferably disposed on the bearing front side opposite to the rear side where the axial load is applied.

By arranging the grease reservoir forming component on the inner diameter surface of the outer race, the bearing can be incorporated into a spindle device or the like in a state in which the grease has been sealed in the grease reservoir, and the workability of assembling is improved.

[0011] In the present invention, the rolling bearing s may be a cylindrical roller bearing, the fixed-side bearing ring may be an outer ring, and the grease reservoir forming parts may be provided on both axial sides of the outer ring. good.

In this configuration, the grease base oil can be continuously supplied to the outer ring raceway surface from the grease reservoir on both sides. In the case of a cylindrical roller bearing, since the roller force acting as a rolling element has a certain length, supplying grease base oil from both sides is preferable in terms of lubrication because it can be supplied evenly in the axial direction. As a result, higher speed, longer life, and maintenance-free operation can be further enhanced. [0012] In the present invention, the rolling bearing may be used for supporting a main shaft of a machine tool.

Maintenance-free machine tools are strongly demanded for high-speed rotation to improve machining efficiency, to prevent bearing heat generation to ensure machining accuracy, and to improve productivity by shortening operation stop time. Therefore, by using the rolling bearing of the present invention, it is possible to effectively achieve the advantages of using the grease sealed in the bearing of the present invention to achieve high speed, long life, and maintenance-free.

[0013] In the present invention, the grease reservoir forming component is in contact with a width surface of the fixed-side race and performs positioning in the axial direction of the race, and is fitted to a peripheral surface of the positioning spacer. It is also possible to have a configuration in which the groove-shaped grease reservoir forming component main body is opened toward the peripheral surface, and the grease reservoir is formed between the positioning spacer and the grease reservoir forming component main body.

Further, the length from the raceway surface to the width surface on the other side is set to be larger than the length from the raceway surface of the fixed raceway to the width surface on one side of the raceway, and the grease reservoir forming component is different from the above. It is good also as composition arranged between the inner ring and the outer ring in the side. According to this configuration, since the grease reservoir forming component is disposed between the inner ring and the outer ring, the rolling bearing can be incorporated into a machine such as a spindle device in a state where the grease has been sealed in the grease reservoir. Therefore, the workability of assembling the bearing is improved.

[0014] In the present invention, the rolling bearing may be used for supporting a main shaft of a machine tool.

Brief Description of Drawings

FIG. 1 is a partial cross-sectional view of a rolling bearing according to a first embodiment of the present invention. FIG. 2 is an enlarged sectional view of a part of the rolling bearing.

FIG. 3 is a cross-sectional view of a machine tool spindle device using the same rolling bearing.

FIG. 4 is a partial cross-sectional view of a rolling bearing according to a second embodiment of the present invention.

FIG. 5 is a partial cross-sectional view of a rolling bearing according to a third embodiment of the present invention.

FIG. 6 is a graph showing test results of examples of the present invention and comparative examples.

FIG. 7 is a partial sectional view of a comparative example.

BEST MODE FOR CARRYING OUT THE INVENTION

A first embodiment of the present invention will be described with reference to FIGS. 1 and 2. In FIG. 1, this rolling S-bearing has an inner ring 1, an outer ring 2, and a plurality of rolling elements 3 interposed between the raceway surfaces la and 2a of the inner and outer rings 1 and 2. And a gap forming piece 7. The plurality of rolling elements 3 are held by a retainer 4, and one end of a bearing space between the inner and outer rings 1 and 2 is sealed by a seal 5. This rolling bearing is an angular ball bearing, and a seal 5 is provided at an end on the back side of the bearing, and a grease reservoir forming component 6 and a gap forming piece 7 are provided on the front side of the bearing. The grease reservoir forming part 6 also serves as a seal on the front side of the bearing, thereby preventing leakage of grease from the front side of the bearing. The cross-hatched portions in the figure indicate the portions filled with grease.

The grease reservoir forming component 6 is a ring-shaped component having a grease reservoir 8 formed therein, and is provided in contact with the front-side width surface of the outer race 2. In this example, the grease reservoir forming component 6 is fitted to the outer ring positioning spacer 9 provided in contact with the front width surface of the outer ring 2 and the inner diameter surface (inner peripheral surface) of the outer ring positioning spacer 9. And a grease reservoir forming component body 10 having a radial outward groove shape. The internal space sandwiched between the outer ring positioning spacer 9 and the dusty reservoir forming component body 10 is a grease reservoir 8. The outer ring positioning spacer 9 has an engagement step 9a at the end opposite to the outer ring 2 on the inner diameter surface, to which the tip of the side wall 10a of the grease reservoir forming component body 10 is fitted. After the grease is filled in the grease reservoir 8, the grease reservoir forming component body 10 engages the side wall portion 10a with the engagement step 9a of the outer ring positioning spacer 9, and stops the inner diameter surface of the engagement step 9a. The outer ring positioning spacer 9 is axially fixed to the outer ring positioning spacer 9 by a retaining ring 11 that engages with the annular groove. Grease accumulation forming part Engagement with the outer diameter surface of the side wall 1 Oa in the product main body 10 and the outer ring positioning spacer 9 Sealing parts 12 and 13 such as O-rings are provided on the inner diameter surface between the step part 9a for use and the inner part of the outer ring positioning spacer 9 and the adjacent part of the outer ring 2 in contact with it to prevent grease leakage. .

The gap forming piece 7 has a ring shape that forms a gap 14 along the inner diameter surface 2 b of the outer ring 2. The gap forming piece 7 is formed integrally with the grease reservoir forming component main body 10. That is, the grease reservoir forming component body 10 integrally extends from the outer diameter end of the side wall portion 10b on the bearing adjacent side.

As shown in FIG. 2 in an enlarged manner, in the angular ball bearing, the inner diameter surface 2b of the outer ring counterbore portion on the front side is a tapered surface having a large diameter on the width side due to the incorporation of the rolling elements 3. There. The gap forming piece 7 extends to the vicinity of the outer raceway surface 2a so as to form a gap 14 having a predetermined gap amount δ along the tapered surface 2b. This gap 14 communicates with the grease reservoir 8. It is sufficient that the gap amount δ of the gap 14 is such that the gap 14 is maintained in the shape of a dart when the grease is filled. The tip 7a of the gap forming piece 7 is brought close to the rolling element 3 so as not to contact the rolling element 3. The inner diameter surface of the front end portion 7a is an inclined surface 7aa whose diameter increases toward the rolling element 3 side. The inclined surface 7aa is liable to accumulate on the tip 7a of the gap forming piece 7 when the Darriese enclosed in the bearing scatters toward the inner diameter of the outer ring due to centrifugal force during the operation of the bearing. It is to be. An inner diameter surface 7b extending from the inclined surface 7aa of the gap forming piece 7 to an outer diameter end of the side wall portion 10b of the grease reservoir forming component body 10 has a rear side of the outer ring 2 in order to avoid interference with the retainer 4. It has a larger diameter than the cage guide surface 2d, which is the inner diameter surface.

The operation of the above configuration will be described. When assembling the bearing, the grease reservoir 8 and the gap 14 are filled with grease. Grease for initial lubrication is sealed in the bearing. By operating the bearing, the grease sealed in the bearing is scattered by centrifugal force, and a part of the grease is deposited on the outer ring raceway surface 2a and the tip 7a of the gap forming piece 7. The grease accumulates here, so that the grease reservoir 8 communicates with the rolling element contact portion 2aa (FIG. 2) on the outer raceway surface 2a. That is, grease is connected between the grease reservoir 8 and the rolling element contact portion 2aa on the outer ring raceway surface 2a. For this reason, the base oil in the grease penetrates and moves due to the capillary action of the thickener, and the base oil power consumed as lubricating oil in the rolling element contact part 2aa passes through the gap 14 from the grease reservoir 8 It is continuously supplied to the rolling element contact part 2aa. From this, the lubrication life of this bearing is determined by the grease consumption in the rolling element contact portion 2aa and the grease accumulation capacity in the grease accumulation 8.

[0021] As described above, the amount of the dalyase base oil consumed as the lubricating oil in the rolling element contact portion 2aa of the outer raceway surface 2a is continuously supplied from the entire circumference of the bearing. In addition, since the lubrication life of the bearing is determined by the amount of grease in the grease pool 8, by designing the grease pool capacity corresponding to the required life, maintenance-free high-speed operation and long life can be achieved.

The features of the rolling bearing according to this embodiment are summarized as follows.

1) Can be used without maintenance.

2) Since the lubricating oil is supplied using the capillary phenomenon, the consumed amount is continuously supplied and the speed can be increased.

3) The grease reservoir 8 can be designed according to the required life.

4) Grease lubrication can increase the speed up to the rotation range of air-oil lubrication, and replacing air-oil lubrication with this lubrication method can be expected to reduce costs, reduce noise, and save energy.

FIG. 3 shows an example of a spindle device for a machine tool using the rolling bearing of the above embodiment. In this machine tool spindle device, two of the above rolling bearings are used as a back combination. The two rolling bearings 23 and 24 rotatably support both ends of the main shaft 21 in the housing 22. The inner ring 1 of each of the rolling bearings 23 and 24 is positioned by an inner ring positioning spacer 26 and an inner ring spacer 27, and is fixed to the main shaft 21 by an inner ring fixing nut 29. The outer ring 2 is positioned and fixed in the housing 22 by an outer ring positioning spacer 9, an outer ring spacer 30, and outer ring pressing lids 31 and 32. The housing 22 is formed by fitting a housing inner cylinder 22A and a housing outer cylinder 22B, and the fitting portion is provided with an oil passage groove 33 for cooling.

The main shaft 21 is provided with a chuck (not shown) for removably attaching a tool or a work (not shown) to a front end 21a thereof, and a rear end 21b is provided with a drive such as a motor. The source is connected via a rotation transmission mechanism (not shown). The motor may be built in the housing 22. This spindle device is, for example, a machining center, lathe, milling machine, grinding machine Etc. can be applied to various machine tools.

According to the spindle device having this configuration, the effects of increasing the speed, extending the life, and maintaining maintenance of the rolling bearings 23 and 24 of this embodiment are effectively exhibited.

FIG. 4 shows a second embodiment of the present invention. In the rolling bearing of this embodiment, a grease reservoir 8 is formed inside the bearing space between the inner and outer rings 1 and 2 by arranging the grease reservoir forming component 6A on the inner diameter surface 2e of the outer ring 2. In this example, the outer ring positioning spacer 9 in the example of FIG. 1 is not a component of the dusty pool forming component 6 A, but is a single component corresponding to the dusty pool forming component body 10 in the example of FIG. 1. 6A is configured. The grease reservoir forming component 6A has an outwardly grooved cross-sectional shape, and a gap forming piece 7 is provided on the body. The gap forming piece 7 and the gap 14 formed by the gap forming piece 7 and the outer ring inner diameter surface 2b are the same as those in the embodiment of FIG.

In this embodiment, the length from the center of the raceway surface 2a of the outer ring 2 to the width surface on the back side of the bearing is longer than the length L1 from the center of the raceway surface 2a to the width surface on the front side of the bearing on which the grease reservoir forming component 6A is arranged. L2 is increased, and the grease reservoir forming part 6 is fitted to the outer ring inner diameter surface 2e of the elongated portion. In this case, the inner and outer rings 1 and 2 have the same width dimension, and the width dimension is made larger than the standard dimension to one side. The drain reservoir forming part 6 is fitted.

[0028] The portion of the inner diameter surface 2b following the raceway surface 2a of the outer race 2 is tapered in consideration of the incorporation of the rolling element 3 similar to the angular ball bearing shown in Fig. 1 and the like. The grease reservoir forming component 6A is fitted to the cylindrical inner surface 2e following the inner surface 2b of the surface. The internal space force between the inner diameter surface 2e and the grease reservoir forming component 6A is a grease reservoir 8.

A gap forming piece 7 is formed at the outer diameter end of the side wall 6b of the grease reservoir forming component 6A, and the gap forming piece 7 is extended along the inner diameter surface 2b of the outer ring 2 to near the raceway surface 2a. The gap 14 is formed and the gap amount of the gap 14 is the same as in the embodiment of FIG.

The side wall 6a on the outer side of the bearing of the grease reservoir forming part 6A is engaged with the engagement step 2f formed on the inner surface 2e of the outer ring, and the stop is engaged with the stop ring groove on the inner surface of the engagement step 2f. It is fixed in the axial direction by a ring 15.

[0029] The inner diameter surface of the inner ring 1 in the width-increased portion is a small-diameter surface portion lc having a smaller diameter with a step than that of the inner diameter surface lb adjacent to the raceway surface la. The grease reservoir 8 is widely secured by protruding the inner diameter of the grease reservoir forming component 6A on the small-diameter surface portion lc side. Other configurations are the same as those of the rolling bearing in FIG.

In this embodiment, since the grease reservoir forming component 6 is arranged on the inner diameter surface 2e of the outer ring 2, the grease reservoir 8 has been filled with grease, and the rolling bearing is mounted on a mechanical device such as a spindle device. Can be incorporated into Therefore, the workability of assembling the bearing is improved.

FIG. 5 shows a third embodiment of the present invention. In this embodiment, the configuration of the grease reservoir forming component 6 in the first embodiment shown in FIG. 1 is applied to a cylindrical roller bearing. The grease reservoir forming parts 6 are provided adjacent to both sides of the outer ring 2 in the axial direction. Other configurations are substantially the same as those in the embodiment of FIG.

In the case of this embodiment, the grease base oil can be continuously supplied to the outer raceway surface 2a from the grease reservoirs 8 on both sides. In the case of cylindrical roller bearings, the rollers that serve as the rolling elements 3 have a certain length, so supplying grease base oil from both sides can be supplied evenly in the axial direction and improves lubricity. preferable. As a result, it is possible to further increase the speed, extend the service life, and maintain-free.

Next, comparison test results will be described. The comparative test was carried out with the rolling bearing (example) of the embodiment of FIG. 1 according to the present invention and the proposed example shown in FIG. The example proposed in FIG. 7 is disclosed in an application filed by the present applicant earlier (Japanese Patent Application No. 2003-343677). The proposed example is provided with a grease reservoir 58 and a gap forming piece 57 that faces the inner ring 51 that is the rotating raceway so as to form a clearance extending from the grease reservoir 58 to the inner raceway surface. The test conditions are as follows.

Test bearing: Anguilla ball bearing with inner ring 100mm

Preload: 2.5kN constant pressure preload

Lubrication: Grease (6cc inside bearing + 25cc grease pool)

FIG. 6 shows the results of the above comparative test.

In the case of the comparative example, the temperature rise is unstable, and the temperature rise is large at 13000 rpm. Therefore, it was not possible to rotate to a high-speed rotation range. This is because, when the gap forming piece 57 is provided facing the inner ring 51, which is the rotating side wheel, the grease receives centrifugal force due to the rotation of the inner ring as the rotation speed increases, and the grease flows into the bearing excessively. It is presumed that the fever increased.

The example was able to operate up to the high-speed range of 20000 rpm. This is because, when the clearance forming piece 7 is provided for the outer ring 1 which is a fixed side ring, the required amount of the base oil of grease flows into the rolling elements 3 due to a capillary phenomenon and is lubricated. That is, it is considered that the lubricating oil is lubricated by the slight amount of the lubricating oil, so that the temperature rise at which the stirring resistance is reduced is stabilized.

In each of the above embodiments, the case in which the grease reservoir forming component 6 and the gap forming piece 7 are provided on the outer ring 2 side has been described.However, when the inner ring 1 is a fixed side wheel, the grease reservoir forming component 6 and the gap forming member 7 are formed on the inner ring 1. Parts 6 and gap forming pieces 7 are provided.

Claims

The scope of the claims

[1] A rolling S-bearing having an inner ring, an outer ring, and a plurality of rolling elements interposed between raceway surfaces of the inner and outer rings. A grease reservoir forming part that is provided in contact with and forms a grease reservoir inside, and a gap that is provided on the stationary raceway and that communicates from the grease reservoir to the vicinity of the raceway surface of the fixed raceway is formed by the raceway surface. And a gap forming piece formed along the peripheral surface formed with the grease. In the gap, the grease base oil in the grease reservoir can be supplied to the vicinity of the raceway surface of the fixed-side raceway due to the capillary action of the thickener. Rolling bearing with a small gap.

[2] The rolling bearing according to claim 1, wherein the fixed side race is an outer race.

[3] The rolling bearing according to claim 2, which is an angular ball bearing, wherein the grease reservoir forming component is provided on an inner diameter surface of an outer ring.

[4] The rolling bearing according to claim 3, wherein the grease reservoir forming component is disposed on a bearing front side.

[5] The rolling bearing according to claim 2, wherein the bearing is a cylindrical roller bearing, and the grease reservoir forming parts are provided on both sides of the outer race in the axial direction.

[6] In claim 1, the grease reservoir forming component is fitted to a positioning spacer which is in contact with a width surface of the fixed-side race and performs positioning in the axial direction of the race, and is fitted to a peripheral surface of the positioning spacer. A rolling bearing having a groove-shaped grease reservoir forming component main body opened toward the lever surface, wherein a darry reservoir is formed between the positioning spacer and the grease reservoir forming component main body.

[7] In claim 1, the length from the raceway surface to the width surface on the other side is set to be larger than the length from the raceway surface of the fixed side race to the width surface on one side of the raceway. A rolling bearing in which a Dally reservoir forming part is disposed between the inner ring and the outer ring on the other side.

[8] A rolling bearing using the rolling bearing according to claim 1 for supporting a main shaft of a machine tool.