JP2003181744A - Main spindle unit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To secure a stable running condition of a bearing by quickly discharging the lubricant used for the inside of the bearing. <P>SOLUTION: A main spindle unit is provided with a lubrication unit 32 which supplies a small amount of lubricant to bearings 12a, 12b via a nozzle 30 at a delivery speed from 10 m/s to 100 m/s and with a delivery quantity from 0.0005 μm<SP>3</SP>/shot to 0.01 μm<SP>3</SP>/shot. At a position in contact with an end face of an outer race 17, there are provided a plurality of radially elongating grooves 34 formed at a plurality of circular positions with predetermined intervals, annular passages 37 formed on a side of the radial grooves 34 opposed to the outer race 17 so as to be almost concentric with the outer race 17, and communicating grooves 36 for communicating the annular passages 37 with the radial grooves 34. The annular passages 37 are connected to an oil outlet port 38. <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 spindle device used in various high speed rotating machines such as machine tools.

[0002]

2. Description of the Related Art Conventionally, for lubrication of bearings for various high-speed rotating main shafts of machine tools and the like, usually, lubricating oil is made into a fine mist,
An oil mist system that conveys compressed air in the air pipe and ejects it toward the inside of the bearing. Lubricating oil droplets (0.01 to 0.03 m1) adjusted to a fixed amount are discharged into the air pipe, and compressed air is used. An oil-air system that carries it to the nozzle and ejects it toward the inside of the bearing, or a jet that uses a high-pressure pump to increase the pressure of the lubricating oil without using an air source, and jets the lubricating oil at high speed from the nozzle with a narrow discharge diameter toward the inside of the bearing. Various methods such as the method are adopted.

[0003]

However, in both the oil mist system and the oil air system lubrication described above, since compressed air is used, noise problems such as wind noise of the air and mist of the lubricating oil may be lost to the atmosphere. The work environment deteriorates due to scattering inside. In addition, since the amount of lubricating oil supplied into the bearing becomes uncertain because the mist of lubricating oil is scattered into the atmosphere, the air curtain is formed with the rotation of the main spindle at high speed rotation. Is hardly supplied to the inside of the bearing, which may cause seizure of the bearing.

Further, in the jet type lubrication, the influence of the air curtain is hardly affected as compared with the oil mist type and the oil air type, but an auxiliary device including a high pressure pump is required and is supplied to the bearing. Since the agitation resistance increases due to the increase in the amount of oil, a large motor is required for driving the main shaft, resulting in high cost.

Therefore, in order to solve such a problem, the present applicant previously proposed a spindle device described in Japanese Patent Application No. 2000-327252. This main spindle device has a discharge speed of 10 m / se to the inside of the bearing through a nozzle.
c or more and 100 m / sec or less, discharge oil amount 0.0005 m
It is equipped with a lubricating device that directly jets and supplies a minute amount of lubricating oil of 1 / shot or more and 0.01 ml / shot or less.

By adopting such a constitution, since compressed air is not used, noise problems such as wind noise of air and deterioration of working environment due to scattering of mist of lubricating oil into the atmosphere can be eliminated. Since the discharging speed of the lubricating oil discharged from the nozzle is as high as 10 to 100 m / sec, the lubricating oil can be reliably supplied to the inside of the bearing without being affected by the air curtain generated during high speed rotation. Further, since the amount of lubricating oil discharged is as small as 0.0005 ml / shot or more and 0.01 ml / shot or less, the rise in bearing temperature can be suppressed to a low level. Furthermore, since an auxiliary device such as a jet system including a high-pressure pump is not used, the stirring resistance does not increase due to the increase in the amount of oil supplied to the bearing, and the motor for driving the main shaft is inexpensive and compact. Can be used.

By the way, it is desirable that the oil used for lubricating the inside of the bearing be quickly discharged to the outside. However, in the spindle device having the above-mentioned structure, although the inside of the bearing can be surely lubricated, Since compressed air is not used to discharge the lubricating oil, the oil cannot be discharged well, and the oil may accumulate near the bearing or inside the bearing, causing the heat generated by rolling resistance to raise the temperature of the bearing.

Therefore, an object of the present invention is to solve the above problems, and it is possible to eliminate noise problems such as wind noise of air and deterioration of working environment due to scattering of mist of lubricating oil in the atmosphere. In addition, the lubricating oil can be reliably supplied to the lubricated surface of the bearing, the rise in bearing temperature can be suppressed to a minimum, and it can be manufactured at low cost. An object of the present invention is to provide a spindle device that can quickly discharge oil after it has been used.

[0009]

The above object of the present invention is to fit a shaft, at least two bearings, which are separated from each other in the axial direction of the shaft, and in which inner rings are fitted, and an outer ring of the bearings. Discharge speed 10m / se into the bearing through the housing and nozzle
c or more and 100 m / sec or less, discharge oil amount 0.0005 m
A spindle device comprising a lubrication device that supplies a minute amount of lubricating oil of 1 / shot or more and 0.01 ml / shot or less, and the inner ring and the outer ring of the bearing are relatively rotatable via rolling elements. A plurality of radially extending radial grooves formed in a circumferential direction at a predetermined interval at a portion in contact with the end face of the outer ring, and concentrically with the outer ring on a side of the radial groove spaced from the outer ring. And a communication passage that communicates the annular flow path with the radial groove, the annular flow path being connected to an oil discharge port for discharging the lubricating oil to the outside. Is achieved by a spindle device.

According to the above structure, the plurality of radial grooves are
Lubricating oil that circulates near the inner circumference on the end face side of the outer ring or stagnates at a certain position depending on the rotation speed and rotation direction of the shaft is efficiently captured regardless of the rotation speed of the shaft. Then, the lubricating oil trapped in the radial groove is guided through the communication passage into the annular flow path that is hardly affected by the air flow due to the rotation of the shaft, and the lubricating oil introduced into the annular flow path is gravitational force. It flows into an oil drain port provided in the lower part of the housing and is discharged to the outside. As a result, the lubricating oil used for lubricating the inside of the bearing can be quickly discharged to the outside, and a stable operating state of the bearing can be secured.

Further, the above object of the present invention is to provide a shaft, at least two bearings in which an inner ring is fitted so as to be separated in the axial direction of the shaft, a housing fitted to an outer ring of the bearing, and a nozzle. Discharge speed of 10 m / sec or more to the bearing through
A lubricating device for supplying a minute amount of lubricating oil of 0 m / sec or less and a discharge oil amount of 0.0005 ml / shot or more and 0.01 ml / shot or less, and the inner ring and the outer ring of the bearing are relative to each other via rolling elements. In a main shaft device that is rotatable, a rotating portion having a lubricating oil guide surface whose outer diameter increases with increasing distance from the inner ring is provided at a portion adjacent to the inner ring end surface on the opposite side of the nozzle. And the housing corresponding to between the axial position where the outer diameter of the lubricating oil guide surface is maximum and the axial position of the inner ring end surface,
The present invention is achieved by a spindle device, which is provided with an oil discharge port for discharging the lubricating oil to the outside.

According to the above construction, as the outer diameter of the lubricating oil guide surface in the rotating portion increases, the outer peripheral speed increases, so that the pressure of the air entrained along with the lubricating oil guide surface in the rotating portion drops to a negative pressure. Becomes So on the other side of the nozzle,
Axial air flow is formed in the direction away from the bearing,
This flow guides the lubricating oil to the oil discharge port. As a result, the lubricating oil used for lubricating the inside of the bearing can be quickly discharged to the outside, and a stable operating state of the bearing can be secured.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, a spindle device according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings. 1 is a cross-sectional view for explaining a spindle device according to a first embodiment of the present invention, FIG. 2 is an enlarged view of a main part of FIG. 1, and FIG. 3 is an overall perspective view of the outer ring spacer shown in FIG. .

First, the main spindle device according to the first embodiment of the present invention will be described. As shown in FIG. 1, the main spindle housing 1 includes a housing main body 2 and a front end (left end in the drawing) of the housing main body 2. Front side bearing housing 3 fixed by internal fitting
And a rear bearing housing 4 fixed to the rear end of the housing body 2. An outer ring pressing member 5 and a front lid 7 are attached to an end of the front bearing housing 3,
A rear lid 10 is attached to the rear bearing housing 4.

The main shaft 11 inserted through the main shaft housing 1 has two front and rear bearings 12a, 12b axially separated from each other in the front bearing housing 3, and one main shaft 11 in the bearing sleeve 4a. It is rotatably supported by two front and rear bearings 13a and 13b which are spaced from each other. The outer rings 17 of the bearings 12a and 12b are fitted into and fixed to the front bearing housing 3 and the inner rings 14 of the bearings 12a and 12b are fixed.
Is externally fitted and fixed to the main shaft 11. In addition, the bearing 13
In each of a and 13b, each outer ring 23 is internally fitted and fixed to the bearing sleeve 4a, and each inner ring 19 is externally fitted and fixed to the main shaft 11. Incidentally, these bearings 12a, 12b, 13a, 13
For b, a rolling bearing such as an angular ball bearing is used.

Between the inner rings 14 of the two front and rear bearings 12a, 12b in the front bearing housing 3, the rear bearing 12b.
Between the inner ring 14 and the step portion 15 of the main shaft 11, and between the inner ring 14 and the inner ring pressing member 6 of the front bearing 12a,
Inner ring spacers 16 are respectively interposed. Further, outer ring spacers 20a and 20b are respectively provided between the outer rings 17 of the front and rear two bearings 12a and 12b, and between the outer ring 17 of the rear bearing 12b and the step portion 18 of the front bearing housing 3. The outer ring 17 of the front bearing 12a that is interposed is pressed axially rearward by the outer ring pressing member 5.

On the other hand, between the inner rings 19 of the two front and rear bearings 13a and 13b in the bearing sleeve 4a, and between the inner ring 19 of the front bearing 13a and the cylindrical portion 21 fitted onto the main shaft 11. Inner ring spacers 22 are respectively interposed, and the inner ring 19 of the rear bearing 13b is axially pressed forward by the inner ring pressing member 9. Further, outer ring spacers 25a and 25b are respectively interposed between the outer rings 23 of the front and rear two bearings 13a and 13b, and between the outer ring 23 of the front bearing 13a and the step portion 24 of the bearing sleeve 4a. The outer ring 23 of the rear bearing 13b is axially pressed forward by the outer ring pressing member 8. Also, the bearing sleeve 4
a is slidably fitted to the inner peripheral surface of the rear bearing housing 4 and is pressed rearward by the spring 4b, so that the bearings 12a, 1
2b and bearings 13a and 13b are preloaded.

A rotor 26 is externally fitted and fixed to a substantially central portion of the main shaft 11 in the axial direction, and a stator 27 is coaxially arranged on the outer peripheral surface side of the rotor 26. The stator 27 is fixed to the inner peripheral surface of the housing body 2 via a stator sleeve 28.

Outer ring spacer 20 on the front bearing housing 3 side
a, 20b and the outer ring spacer 2 on the rear bearing housing 4 side
Nozzles 30 are penetratingly arranged in each of 5a and 25b, and lubricating oil is supplied to the nozzles 30 from a small amount of lubrication device 32 via an oil supply passage 31 formed in the spindle housing 1. ing.

The micro-lubrication device 32 is connected to the bearings 12a, 12 from the discharge port of the nozzle 30 by a control device (not shown).
The discharge speed, the supply interval, the supply amount, and the like of the lubricating oil discharged toward b, 13a, and 13b are controlled to have predetermined values. In this embodiment, the discharge speed of the lubricating oil discharged from the discharge port of the nozzle 30 toward the bearings 12a, 12b, 13a, 13b is 10 m / sec or more.
The discharge oil amount is 0 m / sec or less and 0.0005 ml / shot or more and 0.01 ml / shot or less.

As a result, the same operational effect as that of Japanese Patent Application No. 2000-327252 previously proposed by the present applicant, that is, noise problems such as wind noise of the air and the mist of lubricating oil in the atmosphere are eliminated because compressed air is not used. The work environment can be prevented from deteriorating due to the scattering of water, and the discharge speed of the lubricating oil discharged from the nozzle is as fast as 10 to 100 m / sec. The lubricating oil can be supplied to the inside of the bearing.

The amount of lubricating oil discharged is 0.0005 ml.
Since it is a very small amount of not less than / shot and not more than 0.01 ml / shot, an increase in bearing temperature can be suppressed to a low level. Furthermore,
Since ancillary equipment such as a jet type that includes a high-pressure pump is not used, there is no increase in stirring resistance due to an increase in the amount of oil supplied to the bearings, and an inexpensive small motor is used to drive the spindle. it can.

By the way, normally, the lubricating oil in the main shaft housing 1 is discharged downward due to gravity.
When the rotating body such as 1 rotates at high speed, the lubricating oil does not flow downward due to the influence of the air flow generated by the rotating body, and the outer ring 1
It may circulate around the inner circumference of the housing 7, 23 or the inner circumference of the housing in the vicinity of the outer ring, or may stagnate at a position where the force of the air flow and the gravity balance.

From the micro-lubrication device 32 to each bearing 12a,
The amount of oil supplied to 12b, 13a and 13b is about 0.1 to 0.003 l / min per bearing,
If the oil used for lubrication is not discharged promptly, the rolling resistance in the bearing increases, the bearing temperature rises and becomes unstable, and in the worst case, seizure may occur.

Therefore, in the first embodiment, each bearing 12
a, 12b, 13a, 13b, the outer ring spacers 20a, 20b on the front bearing housing 3 side and the outer ring spacers on the rear bearing housing 4 side for promptly discharging the lubricating oil to the outside. 25a and 25b are configured as follows. Incidentally, each outer ring spacer 20a, 20b, 25a, 25
Since b has the same basic configuration and operational effect based on the present invention, the outer ring spacer 20b shown in FIG. 2 will be described as an example with reference to FIGS. 2 and 3.

As shown in FIG. 2, the outer ring spacer 20b has an outer diameter substantially the same as that of the outer ring 17 of the bearing 12b and an inner diameter slightly larger than the outer diameter of the inner ring spacer 16. ing. As shown in FIG. 3, at the end of the outer ring spacer 20b facing the outer ring 17 side, an annular projection 3 that is slightly thinner than the outer ring 17 is formed.
3 is formed so as to project in the axial direction, and the tip end surface of the annular projection 33 comes into contact with the end surface of the outer ring 17.

A plurality of radial grooves 34 extending in the radial direction are formed on the tip end surface of the annular projection 33 at substantially equal intervals in the circumferential direction. On the side of the radial grooves 34 separated from the outer ring 17. An annular groove 35 is formed on an outer peripheral surface of a central portion of an outer ring spacer 20b in the axial direction, and the annular groove 35 and the radial groove 34 are communicated with each other by a communication groove 36 that constitutes a communication passage. There is. The outer ring spacer 20 on the left side of FIG.
In the case of a, the radial groove 34 and the communication groove 36 are formed at both ends.

The outer peripheral side of the annular groove 35 is closed by the inner diameter surface of the front bearing housing 3 to form a substantially closed annular passage 37 concentric with the outer ring 17. As shown in FIG. 2, the annular flow path 37 is connected to an oil drain port 38 formed in the lower side wall of the front bearing housing 3, which is the lower part of the housing.

That is, a plurality of radial grooves 34 provided in each annular projection 33 of the outer ring spacers 20a, 20b circulate around the inner circumference on the end face side of the outer ring 17 depending on the rotation speed and the rotation direction of the main shaft 11. Or, the lubricating oil that stagnates at a certain position is efficiently captured regardless of the rotation speed of the main shaft 11.

The lubricating oil trapped in the radial groove 34 is introduced into the annular flow path 37 via the communication groove 36. Since the inside of the annular flow path 37 is substantially closed and is hardly affected by the air flow due to the rotation of the main shaft 11, the annular flow path 37 is
The lubricating oil guided to the above flows into the oil discharge port 38 formed in the lower side wall of the front bearing housing 3 by gravity and is discharged to the outside.

Therefore, the bearing 1 on the front bearing housing 3 side
The lubricating oil used for lubricating the inside of 2a, 12b can be quickly discharged to the outside, and a stable operating state of the bearing can be secured. The rear bearing housing 4
The same applies to the side bearings 13a and 13b.

Next, a spindle device according to a second embodiment of the present invention will be described with reference to FIGS. 4 and 5. As shown in FIG. 4, the spindle housing 51 has a housing body 52.
A front bearing housing 53 fitted and fixed to the front end (left end in the figure) of the housing body 52;
2 and a rear bearing housing 54 that is internally fitted and fixed to the rear end thereof. An outer ring pressing member 55 is attached to an end portion of the front bearing housing 53, and the rear bearing housing 5
An outer ring pressing member 58 and a rear lid 60 are attached to the No. 4.

The main shaft 61 inserted through the main shaft housing 51 has two front and rear bearings 62a and 62b axially separated from each other in the front bearing housing 53.
One bearing 63 arranged in the rear bearing housing 54
It is rotatably supported by and.

In the bearings 62a and 62b, each outer ring 67 is internally fitted and fixed to the front bearing housing 53, and each inner ring 64 is externally fitted and fixed to the main shaft 61. Also, the bearing 6
3, the outer ring 73 is internally fitted and fixed to the rear bearing housing 54, and the inner ring 69 is externally fitted and fixed to the main shaft 61. For these bearings 62a and 62b, for example, rolling bearings such as angular ball bearings which are pre-positioned in a fixed combination on the back surface are used, and for the bearing 63, rolling bearings such as cylindrical roller bearings are used.

The inner ring spacer 6 is provided between the inner rings 64 of the two front and rear bearings 62a and 62b in the front bearing housing 53.
6, the inner ring 64 of the rear bearing 62b is the main shaft 61.
The front bearing 62a while being locked to the stepped portion 61a of the
The inner ring 64 is pressed axially rearward by the inner ring pressing member 56. In addition, the front and rear two bearings 62a, 62
An outer ring spacer 70 is interposed between the outer rings 67 of b, and the outer ring 67 of the rear bearing 62b is locked to the step 68 of the front bearing housing 53 and the outer ring 67 of the front bearing 62a. Is pressed axially rearward by the outer ring pressing member 55.

A rotor 76 is externally fitted and fixed to a substantially central portion of the main shaft 61 in the axial direction, and a stator 77 is coaxially arranged on the outer peripheral surface side of the rotor 76. The stator 77 is fixed to the inner peripheral surface of the housing body 52 via a stator sleeve 78.

Outer ring spacer 70 on the front bearing housing 53 side
And the outer ring spacer 75 on the rear bearing housing 54 side,
The nozzles 80 are arranged so as to penetrate therethrough.
0 is an oil supply passage 81 formed in the spindle housing 51.
The lubricating oil is supplied from the micro-lubrication device 82 via the. The micro-lubrication device 82 uses the controller (not shown) to control the bearings 62a, 6a from the discharge port of the nozzle 80.
The discharge speed, the supply interval, the supply amount, and the like of the lubricating oil discharged toward 2b and 63 are controlled to have predetermined values.

Then, in the present embodiment, as in the first embodiment, the bearings 62a, 6 are connected to the bearings 62a, 6 from the discharge port of the nozzle 80.
2b, 63 the discharge speed of the lubricating oil discharged toward 10
m / sec or more and 100 m / sec or less, the discharge oil amount is 0.
It is set to 0005 ml / shot or more and 0.01 ml / shot or less. As a result, it is possible to obtain the same effect as that of Japanese Patent Application No. 2000-327252 previously proposed by the applicant.

Here, in the second embodiment, as shown in FIG. 5, in order to promptly discharge the lubricating oil, which has been used for lubricating the inside of the bearing 62b, to the outside, the opposite side of the nozzle 80 is provided. At a portion adjacent to the end surface of the inner ring 67, there is provided a projection row 65 having a lubricating oil guide surface 65a having an R-shaped cross section whose outer diameter increases as the distance from the inner ring 67 increases. The projection row 65 is a rotating portion that is provided so as to project on the outer peripheral surface of the step portion 61 a of the main shaft 61 and can rotate integrally with the main shaft 61.

The lubricating oil is externally supplied to the front bearing housing 53 which is located between the axial position where the outer diameter of the lubricating oil guide surface 65a is maximum and the axial position of the end surface of the inner ring 64. An oil drain port 88 for discharging oil is provided.

In other words, the lubricating oil guide surface 65a of the projection row 65 which rotates integrally with the main shaft 61 has a higher outer peripheral speed as the outer diameter increases, so that the lubricating oil guide surface 65a of the projection row 65 is formed.
With this, the pressure of the air that is entrained drops and the lubricating oil guide surface 6
There is a negative pressure near 5a. Therefore, on the opposite side of the nozzle 80, an axial air flow is formed in a direction away from the bearing 62b, and this flow guides the lubricating oil to the oil discharge port 88.

As a result, the lubricating oil used for lubricating the inside of the bearing 62b can be quickly discharged to the outside, and a stable operating state of the bearing can be secured. Further, since it is not necessary to form a large number of oil drain grooves such as the radial groove 34, the annular groove 35, and the communication groove 36 in the outer ring spacer 20b of the first embodiment, compared to the spindle device of the first embodiment. , Can be low cost.
Further, if the outer diameter of the projection row 65 is made too large, there arises a problem that the critical speed of the main shaft 61 decreases, so that it is particularly effective for a main shaft having a relatively large critical speed.

It is needless to say that the spindle device of the present invention is not limited to the configuration of each of the above-mentioned embodiments, and can take various forms based on the spirit of the present invention. For example, in the above-described second embodiment, the case where the protrusion row 65 and the main shaft 61 are integrally formed is illustrated, but the protrusion row 65 may be separated from the main shaft 61 as a spacer. Further, in the second embodiment described above, the case where the lubricating oil guide surface 65a of the projection row 65 has the R-shaped cross-section is illustrated, but the invention is not limited to this, and it may have a linear taper shape or a step shape.

[0044]

As described above, according to the above-described spindle device of the present invention, the plurality of radial grooves circulate around the inner periphery of the end face side of the outer ring or stagnate at a certain position depending on the rotation speed and the rotation direction of the shaft. It efficiently captures lubricating oil regardless of the rotation speed of the shaft. Then, the lubricating oil trapped in the radial groove is guided through the communication passage into the annular flow path that is hardly affected by the air flow due to the rotation of the shaft, and the lubricating oil introduced into the annular flow path is gravitational force. It flows into an oil drain port provided in the lower part of the housing and is discharged to the outside. As a result, the lubricating oil used for lubricating the inside of the bearing can be quickly discharged to the outside, and a stable operating state of the bearing can be secured.

[Brief description of drawings]

FIG. 1 is a cross-sectional view for explaining a spindle device according to a first embodiment of the present invention.

FIG. 2 is an enlarged view of a main part of FIG.

3 is an overall perspective view of the outer ring spacer shown in FIG.

FIG. 4 is a sectional view for explaining a spindle device according to a second embodiment of the present invention.

FIG. 5 is an enlarged view of a main part of FIG.

[Explanation of symbols]

1 Spindle housing 11 spindle 12a, 12b bearings 14 Inner ring 17 outer ring 30 nozzles 32 Micro lubricator 34 radial groove 36 communication groove (communication passage) 37 annular flow path 38 Oil drain

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) F16N 31/00 B23Q 1/26 DF term (reference) 3C011 FF06 3C045 FD12 FD18 3C048 AA07 CC04 DD13 EE02 3J101 AA01 AA32 AA42 AA52 AA62 AA81 BA77 CA07 CA08 CA12 CA17 CA22 FA32 GA31

Claims (2)

[Claims] 1. A shaft, at least two bearings in which an inner ring is fitted so as to be separated from each other in the axial direction of the shaft, a housing fitted in an outer ring of the bearing, and a discharge to the bearing through a nozzle. A lubricating device for supplying a minute amount of lubricating oil having a speed of 10 m / sec or more and 100 m / sec or less and a discharge oil amount of 0.0005 ml / shot or more and 0.01 ml / shot or less, wherein the inner ring and the outer ring of the bearing are rolling elements. In the main shaft device that is relatively rotatable via, radial portions extending in the circumferential direction at a predetermined interval in a portion in contact with the end surface of the outer ring, the radial grooves extending in the radial direction, and the radial direction. An annular flow path that is provided concentrically with the outer ring on the side of the groove that is separated from the outer ring, and a communication path that communicates the annular flow path and the radial groove, the annular flow path, Connected to the oil outlet that discharges lubricating oil to the outside Spindle device characterized in that it is. 2. A shaft, at least two bearings in which an inner ring is fitted so as to be separated from each other in the axial direction of the shaft, a housing fitted in an outer ring of the bearing, and a discharge to the bearing through a nozzle. A lubricating device for supplying a minute amount of lubricating oil having a speed of 10 m / sec or more and 100 m / sec or less and a discharge oil amount of 0.0005 ml / shot or more and 0.01 ml / shot or less, wherein the inner ring and the outer ring of the bearing are rolling elements. In the main shaft device that is relatively rotatable via a nozzle, a portion adjacent to the inner ring end surface on the opposite side of the nozzle is provided with a lubricating oil guide surface whose outer diameter increases with increasing distance from the inner ring. A rotating portion is provided, and the lubricating oil is discharged to the outside in the housing corresponding between the axial position where the outer diameter of the lubricating oil guide surface is maximum and the axial position of the inner ring end surface. An oil drain is provided Spindle and wherein the are.