JP2003232372A - Bearing device and spindle device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a bearing device and a spindle device, in which a favorable condition of grease lubrication can be maintained by conducting a stable grease supply and a bearing lifetime can be prolonged. <P>SOLUTION: The bearing device 10 comprises a rolling bearing 12 lubricated with grease, a housing 11 fitted on the outside of the bearing 12, and a grease- supply mechanism 70 for supplying grease in the clearance of the bearing 12. Grease-discharge spaces 19, 22 are provided on both sides in the axial direction of the bearing space. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bearing device used to support a spindle for a main shaft of a machine tool that rotates at high speed.

[0002]

2. Description of the Related Art Conventionally, a bearing device in which a plurality of rolling bearings such as angular ball bearings and cylindrical roller bearings are incorporated in a housing is used to support a spindle for a machine tool spindle. Some of the rolling bearings are mounted side by side in the housing. Grease lubrication, oil-air lubrication,
Lubrication methods such as oil mist lubrication are used. A small amount of lubrication such as oil-air lubrication and oil mist lubrication is suitable for lowering the temperature rise and improving anti-seizure performance in the high-speed rotation range, but noise problems due to air blowing and waste oil treatment in consideration of environmental conservation Due to problems and the like, there is a great demand for grease lubrication.

In the case of grease lubrication, since only the grease inside the bearing is used for lubrication, the grease is deteriorated due to heat generation at high speed and oil film breakage due to sudden acceleration / deceleration operation.
Seizure may occur early. In particular, dmN (=
(Bearing inner diameter + Bearing outer diameter) / 2 x rotation speed (rpm)) 1
It is difficult to guarantee the specified grease life and bearing life in the high-speed rotation range of over 500,000. For the purpose of extending the grease life, a technique of storing grease for replenishment inside the spacer, etc. and a technique of replenishing grease from the outside have been proposed, but further improvements are desired. .

[0004]

As shown in FIG. 6, the inventor of the present invention connects a grease supply device 99 to a bearing device 90 in which a pair of angular ball bearings 92, 92 are arranged side by side in a housing 91. The following tests were conducted. In the test, each bearing 92 was filled with 70% or more of the bearing space volume grease and acclimated to 12000 / min ^{−1, and} then 4% of the bearing space volume was replenished from the grease replenishing device 99 for 12000. It rotated all at once to / min ^-1 . As a result, the temperatures of the bearings 92, 92 were not stable and abnormally generated heat. This is because (1) even if the grease is replenished, the old grease already filled in the bearing space is not discharged smoothly, and the old grease interferes and the new grease cannot lubricate the raceway surface, etc. 2) It is considered that the factor was that old grease discharged from the bearing space of one bearing rushed into the bearing space of the other bearing.

The present invention has been made in view of the above circumstances, and an object thereof is to maintain stable grease replenishment and maintain a good grease lubrication state, which in turn can prolong the life of the bearing. It is to provide a bearing device and a spindle device.

[0006]

The object of the present invention is achieved by the following constitution. (1) A pair of rolling bearings lubricated with grease,
A bearing device comprising a housing fitted onto the rolling bearing and a grease replenishing mechanism for replenishing the bearing space of the rolling bearing with grease, wherein the other of the bearing spaces of the pair of rolling bearings is the other. A space for discharging grease is provided on the side opposite to the side facing the rolling bearings, and a suppressing means is provided to prevent the grease from moving from each bearing space toward the bearing space of the other rolling bearing when replenishing the grease. Bearing device characterized by being provided. (2) A bearing device comprising a rolling bearing lubricated with grease, a housing fitted on the rolling bearing, and a grease replenishing mechanism for replenishing the bearing space of the rolling bearing with grease. A bearing device characterized in that a space for discharging grease is provided on both axial sides of the bearing space of the rolling bearing in the housing. (3) The bearing device according to (2), further including a spacer that comes into contact with a bearing ring of the rolling bearing, and at least a part of the grease discharging space is provided in the spacer. (4) Of the grease discharge spaces provided on both sides in the axial direction of the bearing space, one space is made narrower than the other space so that more grease is discharged to the wider space than the one narrow space. The bearing device according to (2) or (3) above. (5) In the above (1), a seal member is provided on one axial side of the bearing space, and a large amount of grease is discharged to the grease discharge space on the side opposite to the side where the seal member is provided. The bearing device described. (6) The bearing device according to any one of (1) to (5), further including a suction passage communicating with the grease discharging space, through which the grease is sucked from the grease discharging space. (7) A spindle device in which a spindle for machine tool spindle is supported by the bearing device according to any one of (1) to (6). (8) A spindle device supporting an AC servomotor spindle by the bearing device according to any one of (1) to (6).

According to the above construction, when the bearing space is replenished with new grease, the old grease already filled in the bearing space sequentially moves to the grease discharging space. Therefore, old grease does not stay in the bearing space, and it is possible to lubricate the raceways and the like with new grease each time the grease is replenished. By providing the space for discharging grease, it is possible to remarkably prevent old grease from rushing from the bearing space of one rolling bearing to the bearing space of the other rolling bearing. Further, if the suction passage communicating with the grease discharging space is provided, the old grease can be efficiently discharged by sucking the grease from the grease discharging space via the suction passage.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. The embodiments described below are preferably used to support a spindle for machine tool spindles and a spindle for AC servomotors. FIG. 1 shows the first aspect of the present invention.
The bearing device 10 of an embodiment is shown. In the bearing device 10, a pair of rolling bearings 12 and 12 are incorporated in a housing 11 with an interval in the axial direction. The rolling bearing 12 (here, an angular ball bearing of an outer ring counterbore) has an outer ring 13 having an outer ring raceway on its inner peripheral surface, an inner ring 14 having an inner ring raceway on its outer peripheral surface, and an outer ring raceway and an inner ring raceway. It is provided with a plurality of balls 15 rotatably arranged and a cage 16 which holds the balls 15 rotatably. Although not shown, a plurality of other rolling bearings (angular ball bearings, cylindrical roller bearings, etc.) may be incorporated in the housing 11.

The housing 11 includes a grease replenishing device 7
A grease supply hole 11a into which the grease supply pipe 71 provided in No. 0 can be inserted is formed. The grease supply hole 11a is coaxially connected to the grease supply hole 13a formed in the outer ring 13 of the rolling bearing 12. The grease supply hole 13a of the outer ring 13 is provided in the grease supply pipe 7
1 has a first portion into which the grease can be inserted, and a second portion having a diameter smaller than that of the first portion via a step portion that prevents the grease supply pipe 71 from protruding into the bearing space. The second portion is opened at a position on the inner diameter surface of the outer ring 13 which is displaced from the contact point in the outer ring raceway. In the present embodiment, the grease supply hole 11a formed in the housing 11 and the grease supply hole 13a provided in the bearing outer ring 13 function as a grease supply mechanism. Those including the grease supply device 70 and the grease supply pipe 71 may be regarded as the grease supply mechanism.

On the side of each rolling bearing 12 facing the other rolling bearing (counterbore side), an outer ring spacer 17 that is in contact with the outer ring 13 and is a restraining means for restraining movement of grease, An inner ring spacer 18 that abuts the inner ring 14 is provided. Recesses (recessed grooves) 17a, 17a are formed at both ends of the inner peripheral surface of the outer ring spacer 17 in the axial direction so as to increase the inner diameter thereof. The central portion 17b of the outer ring spacer 17 projects inward in the radial direction relative to the recesses 17a, 17a (the inner diameter is reduced), and the inner peripheral surface of the central portion 17b is a minute gap to the outer peripheral surface of the inner ring spacer 18. Is close through. Thus, the outer ring spacer 17 and the inner ring spacer 18 form a grease discharge space 19 on the side of the bearing space of each bearing 12 that faces the other bearing (on the side opposite to the counter bore).

An outer ring spacer 20 and an inner ring spacer 21 are provided on the opposite side (counterbore side) of each rolling bearing 12 opposite to the other rolling bearing. Outer ring spacer 2
0 is provided with a recess similar to the outer ring spacer 17 described above, and the outer ring spacer 20 and the inner ring spacer 21 allow the grease discharging space 22 to be provided on the counter bore side of each bearing 12.
Are formed.

Thus, the grease discharge spaces 19, 22 are formed on both sides of the bearing space of each rolling bearing 12 in the axial direction, and the bearing space and the grease discharge spaces 19, 22 communicate with each other. In this embodiment, the two grease discharge spaces 19 and 22 have substantially the same volume.

When each rolling bearing 12 supports the spindle 81 for the spindle of the machine tool, the life of the grease is generally set to 20,000 hours. Therefore, the volume of the grease discharge spaces 19 and 22 is at least 20000.
The size is set so that the grease can be replenished for more than a time (for example, about 3 to 10 times the bearing space volume).
In this embodiment, two grease discharge spaces 19, 22 are provided.
It suffices that the total sum of the volumes is set to such a size.

A test was conducted using this bearing device 10.
In the test, each bearing 12 was filled with grease of 70% or more of the bearing space volume and acclimated to 12000 / min ^{−1, and} then 4% of the bearing space volume of grease was replenished from the grease replenishing device 70 to 12000. It was rotated all the way to / min ^-1 . As a result, the temperature of the bearing 12 was stable and abnormal heat generation did not occur.

According to the bearing device 10 of the present embodiment, when new grease is replenished in the bearing space, the old grease already enclosed in the bearing space sequentially moves to the grease discharge spaces 19, 22. Therefore, old grease does not stay in the bearing space, and it is possible to lubricate the raceways and the like with new grease each time the grease is replenished. A pair of rolling bearings 12, 12 are arranged at a distance in the axial direction, and a central portion 17b provided on the outer ring spacer 17 is provided.
Thus, it is possible to reliably prevent old grease from moving from the bearing space of one rolling bearing to the bearing space of the other rolling bearing.

FIG. 2 shows a second embodiment of the present invention. In addition,
In the embodiments described below, members having the same configurations and operations as those already described are denoted by the same or corresponding symbols in the drawings, and the description thereof will be simplified or omitted.

In the bearing device 30 of the second embodiment, the outer ring 13 is provided on the side of the rolling bearings 12 arranged at intervals in the axial direction opposite to the other rolling bearing (counter bore side).
The outer ring spacer 37 that contacts the inner ring 14 and the inner ring spacer 18 that contacts the inner ring 14 are provided. At both axial ends of the inner peripheral surface of the outer ring spacer 37, recesses 37a, 37a are provided so as to increase the inner diameter at that location. Outer ring spacer 37
The central portion 37b of the inner peripheral surface 37b projects inward in the radial direction relative to the concave portions 37a, 37a, and its inner peripheral surface is close to the outer peripheral surface of the inner ring spacer 18 with a minute gap. Thus, the outer ring spacer 37 and the inner ring spacer 18 form a grease discharge space 39 on the side of the bearing space of each bearing 12 that faces the other bearing (on the side opposite to the counter bore).

An outer ring spacer 31 and an inner ring spacer 21 are also provided on the opposite side (counterbore side) of each rolling bearing 12 opposite to the other rolling bearing. Outer ring spacer 3
A concave portion having a width (axial dimension) narrower than the concave portion 37a provided in the outer ring spacer 37 is provided at the axial end portion of the inner peripheral surface of the outer ring spacer 31 and the inner ring spacer. Seat 21
Thus, a grease discharge space 32 is formed on the outer side of each bearing 12 in the axial direction.

Thus, the grease discharge spaces 39, 32 are formed on both sides of the bearing space of each rolling bearing 12 in the axial direction, and the bearing space and the grease discharge spaces 39, 32 communicate with each other. In this embodiment, the grease discharging space 39 on the inner side in the axial direction has a larger volume than the space 32 for discharging grease on the outer side in the axial direction.

The grease supply hole 13a provided in the outer ring 13 of each rolling bearing 12 is opened at a position displaced from the contact point of the inner diameter surface of the outer ring in the outer ring raceway to the counterbore side.
That is, the narrow grease discharge space 32 in the outer ring raceway
There is an opening at the side.

According to the bearing device 30 of the present embodiment, when new grease is replenished in the bearing space, much of the old grease already enclosed in the bearing space is discharged into the wider grease discharging space 39. It The internal pressure of the narrower grease discharge space 32 is larger than that of the wider grease discharge space 39.
This is because it tends to be higher than the internal pressure of. The grease replenished from the grease replenishing hole 13a lubricates the outer ring raceway surface, the rolling surface, and the inner ring raceway surface, and then moves to the wider grease discharging space 39. Further, the central portion 37b provided on the outer ring spacer 37 can prevent old grease from moving from the bearing space of one rolling bearing to the bearing space of the other rolling bearing.

FIG. 3 shows a third embodiment of the present invention. The bearing device 40 according to the third embodiment includes an outer ring spacer that abuts the outer ring 13 on the side (counter bore side) of each rolling bearing 12 arranged at intervals in the axial direction that faces the other rolling bearing. An inner ring spacer 48 that contacts the inner ring 14 is provided. At both axial ends of the inner peripheral surface of the outer ring spacer 47, there are provided recesses for increasing the inner diameter. The inner peripheral surface of the central portion 47b of the outer ring spacer 47 is close to the outer peripheral surface of the inner ring spacer 48 with a minute gap.
Thus, the outer ring spacer 47 and the inner ring spacer 48 form a grease discharge space 49 inside the bearings 12 in the axial direction.

An outer ring spacer 20 and an inner ring spacer 21 are provided on the outer side of each rolling bearing 12 in the axial direction. The outer ring spacer 20 and the inner ring spacer 21 form a grease discharge space 22. Has been formed. In this embodiment, the grease discharging space 49 on the inner side in the axial direction is narrower than the space 22 for discharging grease on the outer side in the axial direction.

The grease replenishing hole 13a provided in the outer ring 13 of each rolling bearing 12 is opened at a position displaced from the outer ring raceway on the inner diameter surface of the outer ring to the counterbore side. That is, the opening is provided at a position deviated from the outer ring raceway toward the narrow space 49 for discharging grease. Here, the grease supply hole 13
The opening a opens toward the guide surface of the cage 16.

According to the bearing device 40 of the present embodiment, when new grease is replenished in the bearing space, a large amount of the old grease already filled in the bearing space is discharged to the wider grease discharging space 22. It Grease supply hole 13a
The grease supplied from lubricates the outer ring raceway surface, the rolling surface and the inner ring raceway surface, and then moves to the wider grease discharging space 22. Further, the central portion 47b provided on the outer ring spacer 47 can prevent the grease discharged into the narrow grease discharging space 49 from moving from one rolling bearing space to the other rolling bearing space.

FIG. 4 shows a fourth embodiment of the present invention. The bearing device 50 according to the fourth embodiment includes an outer ring spacer that abuts the outer ring 13 on the side of the rolling bearings 12 arranged at intervals in the axial direction facing the other rolling bearing (counter bore side). 57 and an inner ring spacer 58 that comes into contact with the inner ring 14 are provided. In the present embodiment, the inner peripheral surface of the outer ring spacer 57 does not have irregularities. Then, the outer ring 13 of each rolling bearing 12
, An annular seal member 51 which is a suppressing means for suppressing the movement of the grease on the side facing the other rolling bearing.
Is provided. The seal member 51 may be a non-contact type (shield or the like) whose tip portion (inner peripheral portion) does not contact the inner ring 14 or a contact type.

An outer ring spacer 20 and an inner ring spacer 21 are provided on the outer side in the axial direction of each rolling bearing 12, and the outer ring spacer 20 and the inner ring spacer 21 form a grease discharge space 22. Has been done. The grease replenishing hole 13a provided in the outer ring 13 of each rolling bearing 12 is opened at a position displaced from the outer ring raceway on the inner diameter surface of the outer ring to the counter bore side. That is, the opening is provided at a position displaced from the outer ring raceway to the seal member 51 side. Here, grease supply hole 1
3a opens toward the guide surface of the retainer 16.

According to the bearing device 40 of the present embodiment, when new grease is replenished in the bearing space, a large amount of the old grease already filled in the bearing space is discharged to the grease discharging space 22. The seal member 51 suppresses the old grease from attempting to penetrate from the bearing space of the one rolling bearing 12 into the bearing space of the other rolling bearing. The grease replenished from the grease replenishing hole 13a lubricates the outer ring raceway surface, the rolling surface, and the inner ring raceway surface, and then moves to the grease discharge space 22.

FIG. 5 shows a fifth embodiment of the present invention. In the bearing device 60 of the fifth embodiment, the suction passage 11 is provided in the housing 11.
b is provided. Other configurations are substantially the same as those in the third embodiment here, but may be similar to those in the first embodiment, the second embodiment, or the fourth embodiment. That is, such a suction passage 11b can be applied to any of the above-described embodiments. The suction passage 11b is provided in the housing 1
1 communicates with the respective wide spaces 22 for discharging grease. Through the suction passage 11b, old grease in the grease discharging space 22 is regularly sucked by suction means (not shown).

The present invention is not limited to the above-described embodiment, but can be appropriately modified and improved. For example, a rolling bearing such as a cylindrical roller bearing may be used instead of the angular ball bearing. Further, instead of replenishing the grease through the grease replenishing hole 13a provided in the outer ring 13, the grease may be replenished directly from the side of the bearing to the bearing space, or the grease may be replenished from the grease reservoir on the inner ring side. You may. That is, the method of replenishing grease does not matter.

[0031]

As described above, according to the present invention,
(EN) Provided are a bearing device and a spindle device, which can maintain a good grease lubrication state by performing stable grease replenishment and can extend the life of a bearing.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a first embodiment of the present invention.

FIG. 2 is a sectional view showing a second embodiment of the present invention.

FIG. 3 is a sectional view showing a third embodiment of the present invention.

FIG. 4 is a sectional view showing a fourth embodiment of the present invention.

FIG. 5 is a sectional view showing a fifth embodiment of the present invention.

FIG. 6 is a cross-sectional view of an apparatus used to investigate the behavior of grease.

[Explanation of symbols]

10, 30, 40, 50, 60 Bearing device 11 housing 11b suction path 12 Rolling bearing 13 outer ring (race ring) 14 Inner ring (race ring) 17, 20, 31, 37, 47 Outer ring spacer (spacer) 19,22,39,49 Grease discharge space 51 seal member 70 Grease supply device

Claims (8)

[Claims] 1. A bearing device comprising: a pair of rolling bearings lubricated with grease; a housing externally fitted to the rolling bearing; and a grease replenishing mechanism for replenishing the bearing space of the rolling bearing with grease. There is a grease discharge space on the opposite side of the bearing space of each of the pair of rolling bearings from the side facing the other rolling bearing, and when the grease is replenished, from each bearing space to the bearing of the other rolling bearing. A bearing device comprising: a suppressing unit that suppresses grease from moving toward a space. 2. A rolling bearing lubricated with grease,
A bearing device comprising: a housing externally fitted to the rolling bearing; and a grease replenishing mechanism for replenishing the bearing space of the rolling bearing with grease, wherein the axial direction of the bearing space of the rolling bearing in the housing. A bearing device characterized in that a space for discharging grease is provided on both sides. 3. The bearing device according to claim 2, further comprising a spacer that comes into contact with a bearing ring of the rolling bearing, wherein at least a part of the grease discharging space is provided in the spacer. 4. A grease discharging space provided on both sides in the axial direction of the bearing space, wherein one space is narrower than the other space, and a large amount of grease is discharged from the one narrow space to the other wide space. The bearing device according to claim 2 or 3, configured as described above. 5. A seal member is provided on one axial side of the bearing space, and a large amount of grease is discharged to a grease discharge space on the side opposite to the side on which the seal member is provided. Bearing device according to. 6. The bearing device according to claim 1, further comprising a suction passage communicating with the grease discharging space, through which grease is sucked from the grease discharging space. 7. A spindle device supporting a spindle for a machine tool spindle by the bearing device according to claim 1. 8. A spindle device supporting an AC servomotor spindle by the bearing device according to claim 1.