JP2001173407A - Air turbine driving spindle device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a strong brake force with a simple structure and a low cost while avoiding reduction of a turbine efficiency. SOLUTION: A brake mechanism 21 is disposed on an air turbine driving spindle device provided with a journal bearing part 4 and thrust bearing parts 5a, 5b, for rotating a main spindle 3 by jetting compressed air to a plurality of recessed parts 11 disposed on an outer periphery of the main spindle 3. The brake device 21 is composed of a pressure chamber 23 faced to a thrust board 3b end surface of the main spindle 3, and a braking air feeding part 22 for supplying air to the pressure chamber 23. When air is supplied from the braking air feeding part 22 to the pressure chamber 23, the main spindle 3 is displaced in the axial direction by air pressure of the pressure chamber 23, and is brought into contact with a bearing sleeve 6. As a result, a braking force is applied to the main spindle 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an air turbine drive spindle device for supplying rotary power by blowing compressed air to a main shaft. This machine is a drilling machine, precision machine,
It can be used as a spindle device for an electrostatic coating machine or the like.

[0002]

2. Description of the Related Art FIGS. 9 and 10 illustrate a conventional air turbine drive spindle device using a hydrostatic air bearing. In this spindle device, a plurality of recesses 110 are provided on the outer periphery of a thrust plate 30b provided on the main shaft 30, and
A driving air turbine provided with a plurality of turbine nozzles 120 tangentially opened at a position facing the air turbine 110, and a turbine air supply passage 150 extending in a circumferential direction from a turbine air inlet 140.
The compressed air supplied through the nozzle is blown from the turbine nozzle 120 to the radial wall surface 110a of the recess 110 to rotate the main shaft 30. The air that has given the rotational power to the main shaft 30 is discharged out of the housing 20 through the exhaust ports 160a and 160b.

The main shaft 30 is rotatably supported on the housing 20 in two directions, radial and thrust, by a journal bearing 40 and thrust bearings 50a and 50b. The two bearing portions 40, 50a and 50b are static pressure air bearings that support the main shaft 30 in a non-contact manner by the static pressure of the compressed air introduced into the small journal bearing clearance and the thrust bearing clearance.

Depending on the application of this type of air turbine drive spindle device, etc., sudden braking of the main shaft may be required. In this case, a brake mechanism is added to the spindle device. The brake mechanism shown in FIG. 9 and FIG.
It has a brake nozzle 220 that is inclined in the opposite direction to the turbine nozzle 120. By blowing air from the brake nozzle 220 to the bottom 110b of the recess 110, the spindle 30
(At this time, the supply of air from the turbine nozzle 120 is shut off).

FIG. 11 and FIG. 12 show another example of a brake mechanism, in which a braking air turbine is newly added, and this is provided in parallel with a driving air turbine. A plurality of rows of recesses 110 and 210 are provided side by side on the outer periphery of the thrust plate 30b, and one of the rows of recesses 110 (drive recesses) and the turbine nozzle 120 opposed thereto drive air for driving the main shaft 30. A turbine is configured. The other row of recesses 210 (braking recess)
Has a circumferential direction opposite to that of the driving concave portion 110, and the braking concave portion 210 and the brake nozzle 220 opposed thereto constitute a braking air turbine. At the time of forward rotation, with the air supply to the braking air turbine shut off, compressed air is supplied from the air supply port 140 to the turbine nozzle 120 via the circumferential air supply passage 150, and the compressed air is supplied to the drive recess 110. To rotate the main shaft 30 forward. During braking, compressed air is supplied from the intake port 240 to the brake nozzle 220 through the circumferential air supply passage 250 while the air supply to the driving air turbine is shut off, and the compressed air is supplied to the braking recess 210.
To apply a braking force to the main shaft 30 in the reverse rotation direction. The used air is exhausted out of the housing 20 through the exhaust port 160.

[0006]

In the constructions shown in FIGS. 9 and 10, the concave portion 110 for driving the spindle is also used for braking, so that the efficiency of conversion into braking force is low. Further, the brake nozzles 220 must be arranged so as not to interfere with the turbine nozzle 120 for normal rotation, and the number of the brake nozzles 220 cannot be sufficiently secured. For these reasons, it is difficult to obtain a strong braking force.

On the other hand, in the configuration shown in FIGS. 11 and 12,
Since a dedicated braking air turbine is provided in addition to the driving air turbine, a strong braking force can be secured.
However, since the driving air turbine and the braking air turbine are arranged side by side in the axial direction, the overall length of the main shaft is long, and the moment of inertia increases, which is disadvantageous during acceleration and deceleration. In addition, when the main shaft 30 rotates forward, air resistance is generated in the braking recess 210 formed in the opposite direction, so that the driving efficiency is reduced.
Further, there is a concern that the cost may be increased by separately manufacturing the braking air turbine.

Accordingly, an object of the present invention is to provide an air turbine drive spindle device capable of obtaining a strong braking force with a simple structure at low cost while avoiding a decrease in turbine efficiency.

[0009]

As described above, the air turbine drive spindle device includes a main shaft, a journal bearing portion for supporting the main shaft in a radial direction with respect to a fixed member, and a main shaft in a thrust direction with respect to the fixed member. And a thrust bearing portion for supporting the main shaft, and blowing compressed air to a plurality of concave portions provided on the outer periphery of the main shaft to apply rotational power to the main shaft. According to the present invention, a brake mechanism that generates a braking force by adding the spindle device to the fixed member by displacing the spindle in the axial direction by air pressure is added to the spindle device.

With such a structure that a braking force is obtained by contact between the main shaft and the fixed member, the brake air turbine shown in FIGS. 11 and 12 can be omitted, and the turbine efficiency can be improved by reducing the rotational resistance. And a reduction in the size in the axial direction and a reduction in cost due to a reduction in manufacturing cost are achieved. An air turbine has a small mass added to a main shaft and a very small moment of inertia as compared with an electric motor or the like, so that a braking torque may be small. Therefore, even if the main shaft is pressed against the fixing member with a weak force, the main shaft can be reliably stopped in a very short time. Further, in this case, the amount of air is sufficient to displace the main shaft in the axial direction, so that the amount of air used can be reduced as compared with the conventional case where air is blown from the brake nozzle.

The brake mechanism comprises, for example, a pressure chamber facing the main shaft in the axial direction, and a braking air supply unit for supplying air to the pressure chamber. Since the pressure chamber becomes high pressure by supplying air from the braking air supply unit to the pressure chamber, an axial pushing force acts on the main shaft, and the main shaft is displaced in the axial direction. In this case, the pressure chamber is sealed with a non-contact seal, and if the leakage of air is prevented or suppressed by the flow resistance of the non-contact seal, the pressure in the pressure chamber increases, so that the braking force is more efficiently applied to the main shaft. can do.

It is desirable that the pressure chamber is formed in a shape symmetrical with respect to the central axis of the main shaft. Thereby, the pushing force of the main shaft by air pressure acts only in the axial direction, and the axial displacement of the main shaft can be performed stably.

The pressure chamber may be provided on either the fixed member or the main shaft, or may be provided on both.

When an exhaust passage is provided to guide the exhaust of the thrust bearing opposite to the main shaft displacement direction during braking by the brake mechanism to the outside (outside of the spindle device), the exhaust passage is shut off during braking by the brake mechanism. Since the bearing reaction force of the thrust bearing portion on the opposite side to the main shaft displacement direction increases and acts in the same direction as the pressing force of the main shaft by the pressure chamber, a stronger braking force can be obtained.

Among the bearings, at least the thrust bearing can be constituted, for example, by a static pressure air bearing which supports the main shaft by the static pressure of air introduced into the thrust bearing gap. In this case, the air supply system to the thrust bearing (air supply source, piping, etc.)
Can be used for air supply to the brake mechanism, and the existing air supply system can be effectively used. The thrust bearings support the main shaft in both thrust directions, so both sides in the axial direction sandwiching the main shaft (the axial displacement side and the non-displacement side of the main shaft)
Respectively.

When the thrust bearing is constituted by a static pressure air bearing, a high-precision sealing device can be easily obtained if the non-contact seal for sealing the pressure chamber is constituted by the thrust bearing gap. This can be realized, for example, by opening a portion of the pressure chamber on the main shaft displacement side to a thrust bearing gap of a thrust bearing portion arranged on the main shaft counter-displacement side (opposite to the main shaft displacement direction).

In the case where the thrust bearing is constituted by a static pressure air bearing, if the supply of air to the thrust bearing on the main shaft displacement side is interrupted during braking, a resistance to the pushing force of the main shaft during braking (bearing). Since the reaction force) disappears, a stronger braking force can be obtained.

Also, if the axial displacement of the main shaft until the main shaft contacts the fixed member during braking is smaller than the width of the thrust bearing gap on the main shaft displacement side, the contact between the thrust bearing surface and the mating member can be reduced. Thus, it is possible to prevent a decrease in the accuracy of the thrust bearing surface due to the contact between the two. This can be realized, for example, by providing a contact portion between the main shaft and the fixed member at the time of braking so as to protrude from the thrust bearing surface.

If graphite is interposed between the contact portion between the main shaft and the fixing member, the wear of both will be reduced by the self-lubricating action of graphite, so that the durability can be improved.

[0020]

BRIEF DESCRIPTION OF THE DRAWINGS FIG.
A description will be given based on FIG.

As shown in FIG. 1, an air turbine drive spindle device 1 according to the present invention has a main shaft 3 composed of a shaft portion 3a on an inner peripheral portion of a housing 2 and a thrust plate 3b press-fitted or integrally formed at the tip thereof. And the main shaft 3 is rotatably supported in a non-contact manner in both a radial direction and a thrust direction by a bearing portion, for example, a journal bearing portion 4 composed of a hydrostatic air bearing and a pair of thrust bearing portions 5a and 5b. The bearing portions 4, 5a and 5b may have a bearing structure other than the hydrostatic air bearing.

The housing 2 is a cylindrical housing body.
2a and a closing member 2b for closing one end of the opening. The housing body 2a has a large diameter portion 2a1 and a small diameter portion 2a2.
The shaft portion 3a of the main shaft 3 is accommodated on the inner diameter side of the small diameter portion 2a2, and the thrust plate 3b of the main shaft 3 is accommodated on the inner diameter side of the large diameter portion 2a1. The closing member 2b is located at a position facing the thrust plate 3b, and closes the opening of the large diameter portion 2a1 of the housing body 2a at this position.

A bearing sleeve 6 is fixed to the inner peripheral surface of the housing body 2a. A journal bearing surface 4a1 is formed on the inner peripheral surface of the bearing sleeve 6 so as to face the outer peripheral surface of the shaft portion 3a of the main shaft 3 via a small journal bearing clearance Cj. A flange 6a is formed at one end of the bearing sleeve 6 and extends outwardly. The first end of the flange 6a opposes one end of the thrust plate 3b via a small first thrust bearing clearance Csa. A thrust bearing surface 5a1 is formed.

A bearing member 7 is mounted at the center of the closing member 2b so as to face the thrust plate 3b, and the other end surface of the thrust plate 3b and a minute second thrust bearing clearance Csb are provided on the end surface of the bearing member 7. A second thrust bearing surface 5b1 opposed to the second thrust bearing surface 5b1 is formed. On the journal bearing surface 4a1 and the first and second thrust bearing surfaces 5a1 and 5b1, fine bearing nozzles 9a and 9b are opened at a plurality of respective positions, and air is supplied through a supply passage (not shown). When compressed air is supplied to the bearing nozzles 9a and 9b from a source (both not shown), the journal bearing clearance Cj and both thrust bearing clearances Csa and Csb are provided.
Compressed air is introduced into the bearings and the respective bearing clearances Cj and Csa
A journal bearing portion 4 for supporting the shaft portion 3a of the main shaft 3 in a non-contact manner in Csb in a radial direction, and a first thrust bearing portion 5a for supporting a thrust plate 3b of the main shaft 3 in a non-contacting manner in both thrust directions.
And a second thrust bearing portion 5b.

The main shaft 3 is driven by the same air turbine drive as the conventional spindle device shown in FIGS. 9 to 12, and a plurality of recesses are formed on the outer periphery of a thrust plate 3b of the main shaft 3 as shown in FIG.
A plurality of turbine nozzles 12 are arranged at positions facing the recesses 11, and compressed air is blown from each turbine nozzle 12 to the recesses 11 of the thrust plate 3 b to rotate the main shaft 3 in the arrow P direction in the forward direction. The air that has given the rotational force to the main shaft 3 is exhausted from the housing 2 through the exhaust port 16.

In this embodiment, the turbine nozzle 12
Is provided in the annular nozzle member 13 fixed to the inner peripheral surface of the large-diameter portion 2a1 of the housing body 2a in the tangential direction of the thrust plate 3b. Compressed air is supplied to each turbine nozzle 12 from an air supply port 14 connected to an air supply source (not shown) through an annular groove provided on the inner peripheral surface of the large-diameter portion 2a1 so as to face the nozzle member 13.
Done through fifteen. The annular groove 15 may be provided on the outer peripheral surface of the nozzle member 13.

Each recess 11 is provided with a pressure-receiving surface 11a extending in a substantially radial direction and having an arc-shaped cross section, and a flat bottom portion 11b extending from the inner diameter end of the pressure-receiving surface 11a in the reverse rotation direction of the main shaft 3.

In the air turbine drive spindle device according to the present invention, a brake for applying a braking force to the main shaft 3 by displacing the main shaft 3 to one side (for example, the right side in the drawing) in the axial direction and contacting the fixed member by air pressure. A mechanism 21 is provided. “Fixed member” means a non-rotating member. In FIG. 1, the housing main body 2a, the closing member 2b, the bearing sleeve 6, the bearing member 7, and the nozzle member 13 are respectively fixed members. The present invention has a structure in which the main shaft 3 is displaced in the axial direction by pneumatic pressure, and the main shaft 3 is brought into contact with any of the above-mentioned fixing members, thereby obtaining a braking force by the friction.

A brake mechanism 21 shown in FIG. 1 is an example in which a thrust plate 3b of a main shaft 3 is brought into contact with a flange portion 6a of a bearing sleeve 6 to obtain a braking force. The braking mechanism 21 supplies compressed air from an air supply source (not shown). An air supply unit 22 and a pressure chamber 23 that faces a part of the main shaft 3, for example, the thrust plate 3 b in the axial direction, and that introduces compressed air from the braking air supply unit 22. Pressure chamber 23 shown in FIG.
Is a second thrust bearing portion whose part on the main shaft displacement side (right side in the drawing) is arranged on the side opposite to the main shaft 3 of the main shaft 3 (left side in the drawing).
An opening is formed in the second thrust bearing gap Csb of 5b, for example, by forming an annular groove coaxial with the main shaft 3 in the end face of the closing member 2b facing the outer peripheral edge of the thrust plate 3b. Is done. A part of the air supply system (air supply source, piping, etc.) to the brake air supply unit 22 can be used as the air supply system to each bearing unit 4, 5a, 5b. The system can be used effectively.

The inner and outer diameter sides of the pressure chamber 23 are sealed by a narrow non-contact seal 24 (gap seal 24). The flow path resistance of the gap seal 24 prevents or suppresses air leakage from the pressure chamber 23, so that the internal pressure of the pressure chamber 23 increases,
The pushing force acting on the main shaft 3 can be increased.
When the main shaft displacement side of the pressure chamber 23 is opened to the second thrust bearing gap Csb as in the present embodiment, the second thrust bearing gap Csb on the inner diameter side and the outer diameter side of the pressure chamber 23 functions as the gap seal 24 as it is. I do. Generally, the thrust bearing clearance Csb
Is processed with high accuracy, and with such a structure, the high-precision gap seal 24 can be easily obtained. Of course, if there is no particular problem, the pressure chamber 23 may be sealed with a non-contact seal provided separately from the thrust bearing gap Csb.

Compressed air is supplied from the braking air supply section 22 to the pressure chamber 23, and when the pressure chamber 23 becomes high pressure, the air pressure exerts a pushing force on the thrust plate 3b to the right in the drawing. This pushing force F (the product of the internal pressure of the pressure chamber 23 and the projected area of the pressure chamber 23 on the main shaft displacement side) is the first thrust bearing portion on the main shaft displacement side.
If it is larger than the axial bearing reaction force f generated in 5a (F>
f) The main shaft 3 is displaced to the right in the drawing. As described above, the pressure chamber 23 has an axially symmetric shape coaxial with the main shaft 3, for example, an annular shape, and the compressed air entering the same generates a uniform pressure over the entire circumference in the circumferential direction. And the main shaft 3 can be displaced in the axial direction stably. Normally, the static pressure air bearing, especially the bearing surface 4a1 of the journal bearing part 4 has high guide accuracy in the axial direction. Therefore, even when the main shaft 3 is displaced in the axial direction as in the present invention, vibration due to one-sided contact, uneven wear, etc. Is avoided.

The axial displacement of the main shaft 3 causes the thrust plate 3b
Comes into contact with the end surface of the flange portion 6a of the bearing sleeve 6, that is, the first thrust bearing surface 5a1, the friction between the two causes the main shaft 3 to move.
Is given a braking force. Since the braking force acting on the main shaft 3 is substantially proportional to the pushing force F, the braking force can be controlled by adjusting the supply pressure of the braking supply unit 22. The air used for braking is applied to each bearing part 4, 5a, 5b
For example, the air is exhausted from the exhaust port 16 together with the exhaust from the exhaust port.

As described above, in the present invention, since the braking force is obtained by the friction caused by the contact between the main shaft 3 and the flange portion 6a of the bearing sleeve 6, a braking air turbine such as the conventional one shown in FIGS. Becomes unnecessary. Therefore, it is possible to achieve an improvement in turbine efficiency by reducing rotation resistance, a reduction in size in the axial direction, a reduction in manufacturing cost, and the like. An air turbine has a small mass added to the main shaft 3 and a very small moment of inertia as compared with an electric motor or the like. Therefore, even if the main shaft 3 is pressed against the bearing sleeve 6 with a small force, the main shaft 3 can be reliably formed in a short time. Can be stopped. Therefore, a higher braking force can be obtained as compared with the conventional products shown in FIGS. Further, the amount of air used in this case is sufficient to displace the main shaft 3 in the axial direction and compensate for the leakage of the gap seal 24. The air consumption at the time can be reduced.

In the present embodiment, since the contact portion between the main shaft 3 and the bearing sleeve 6 during braking is located in the first thrust bearing gap 5a1 on the main shaft displacement side, wear powder and the like generated by the contact between the two are reduced.
The exhaust gas is quickly exhausted from the exhaust port 16 together with the exhaust gas from the first thrust bearing portion 5a. Therefore, wear powder and the like do not remain in the bearing gap, and the bearing function is stably maintained for a long time. Similar effects can be obtained not only by arranging the contact portion in the thrust bearing gap, but also by arranging it in the vicinity of the thrust bearing gap 5a1 (portion where the exhaust flow acts).

If the bearing sleeve 6 is made of a graphite material, its self-lubricating property can suppress wear on the contact surface between the bearing sleeve 6 and the thrust plate 3b, thereby improving durability. In addition to the graphite material, the end surface of the flange 6a of the bearing sleeve 6 may be subjected to an appropriate surface treatment (for example, formation of a graphite coating) to improve its durability. Of course, the same processing may be performed on the thrust plate 3b side. In order to further improve the durability, it is desirable that the contact surface with the graphite material (the end surface of the thrust plate 3b in the present embodiment) is formed of a metal material having high hardness.

Hereinafter, another embodiment of the present invention will be described.
Unless otherwise described below, the configuration and operation of each drawing are the same as those of FIGS. 1 and 2, and thus common members will be assigned the same reference numerals and redundant description will be omitted.

FIG. 3 shows an embodiment in which the main shaft 3 is displaced in a direction opposite to that of FIG. 1, and the thrust plate 3b is brought into contact with the end face of the bearing member 7 to apply a braking force to the main shaft 3. In this case, the braking air supply section 22 and the pressure chamber 23 are provided, for example, on the end face of the housing large diameter section 2a1 facing the thrust plate 3b,
23 is formed in an annular groove shape coaxial with the main shaft 3 on the outer diameter side of the bearing sleeve 6. When compressed air is supplied from the braking air supply unit 22 to the pressure chamber 23, the main shaft 3 is axially displaced to the left in the drawing, and the thrust plate 3b comes into contact with the end surface of the bearing member 7, so that the braking force is applied to the main shaft 3. Is given. From a viewpoint similar to the above, it is desirable that the bearing member 7 be formed of a graphite material or that the surface treatment be performed on the end surface of the bearing member 7.

FIG. 4 shows the configuration of FIG. 1 and FIG.
In this embodiment, the pressure chamber 23 is provided on the thrust plate 3b of the main shaft 3 (the braking air supply unit 22 is provided on the closing member 2b as in FIG. 1). When compressed air is supplied from the braking air supply unit 22 to the pressure chamber 23, the thrust plate 3b is displaced in the axial direction by receiving a pushing force on the right side in the drawing, and contacts the flange 6a of the bearing sleeve 6 to control the main shaft 3. Power is applied. The pressure chamber 23 may be provided only on the thrust plate 3b as shown in the drawing, or may be formed on both the thrust plate 3b and the closing member 2b. This configuration can be similarly applied to a case where the main shaft 3 is displaced to the opposite side in the axial direction (left side in the drawing) as shown in FIG.

FIG. 5 shows the configuration of FIG. 1 and FIG.
In this embodiment, the pressure chamber 23 is not an annular groove but a cylindrical space coaxial with the main shaft 3. In this case, the bearing member 7 is a pressure chamber
It is arranged in a ring shape on the outer diameter side of 23. As in FIG. 3, the pressure chamber 23 may be provided on the housing body 2a side to displace the main shaft 3 in the opposite axial direction, or the pressure chamber 23 may be provided on the main shaft 3 side as in FIG.

FIG. 6 shows the configuration of FIG. 1 and FIG.
The supply of air to the first thrust bearing portion 5a on the main shaft displacement side is performed independently of the supply of air to the journal bearing portion 4 and the second thrust bearing portion 5b on the side opposite to the main shaft.
In addition, air is supplied to the first thrust bearing portion 5a through a dedicated air supply path 25 having an annular groove 25b. In this case, if only the air supply to the air supply path 25 is interrupted during braking, a bearing reaction force f that resists the pushing force F is not generated, so that a higher braking force can be obtained. This configuration is applicable to the case where the pressure chamber 23 is provided on the housing body 2a side and the main shaft 3 is displaced to the opposite side in the axial direction as in FIG. 3, or the case where the pressure chamber 23 is provided on the main shaft 3 side as in FIG. The same can be applied.

FIG. 7 shows the configuration of FIG. 1 and FIG.
The exhaust from the second thrust bearing portion 5b is performed via an independent exhaust passage 26. The exhaust passage 26 includes, for example, an axial exhaust port 26a provided in an axial core portion, and an axial exhaust port.
A radial exhaust port 26b communicating with the radial exhaust port 26b and an annular groove 26c provided on the end face of the closing member 2b near the pressure chamber 23 and communicating with the radial exhaust port 26b. A switching valve (not shown) is provided in the exhaust passage 26 so that the exhaust passage 26 can be switched between a shut-off state and an open-to-atmosphere state. At the time of forward rotation of the main shaft 3, the switching valve is opened to the atmosphere to allow the second thrust bearing portion 5b to function.
Cut off 26. Thereby, at the time of braking, since the second thrust bearing gap Csb and the inner diameter side portion of the second thrust bearing portion 5b become a high-pressure air reservoir, the pushing force F increases, and a stronger braking force can be obtained. . When a small braking force is sufficient, the pressure chamber 23 can be omitted. This configuration can be similarly applied to any of the embodiments shown in FIGS.

FIG. 8 shows the amount of axial displacement of the main shaft 3 until the main shaft 3 contacts the fixed member during braking in the configuration of FIGS. 1 and 2 (however, the illustration of the air turbine drive unit is omitted). This is smaller than the width of the thrust bearing gap Csa on the displacement side. This is configured by, for example, arranging a ring-shaped contact member 27 that comes into contact with the thrust plate 3b of the main shaft 3 at the time of braking so as to protrude from the first thrust bearing surface 5a1 on the main shaft displacement side, as shown in the figure. When braking,
The thrust plate 3b is an end surface 27a of the contact member 27 as a fixing member.
(Contact surface) while contacting the first thrust bearing surface 5a1
Therefore, the first thrust bearing surface 5a1 can be prevented from being worn, and the durability can be improved. It is sufficient that the contact surface 27a of the contact member 27 is located at a position protruding from the first thrust bearing surface 5a1, and as long as the contact surface 27a satisfies this condition, for example, the contact member 27 is integrally formed with the housing body 2a, or It can be arranged on the end face of the flange portion 6a of the sleeve 6. The contact member 27 is made of graphite,
By applying an appropriate surface treatment to the contact surface 27a, the contact surface
The durability of 27a can be further improved. This embodiment is applicable to any of the embodiments shown in FIGS.

[0043]

According to the present invention, the air turbine for the brake can be omitted, so that the turbine efficiency can be improved by reducing the rotational resistance, the axial dimension can be reduced, or the manufacturing cost can be reduced. Is achieved. In addition, since a sufficient braking force can be obtained with a simple structure and the amount of air used is small, the cost reduction effect is high.

[Brief description of the drawings]

FIG. 1 is a sectional view of an air turbine drive spindle device according to the present invention.

FIG. 2 is a sectional view taken along line AA in FIG.

FIG. 3 is a cross-sectional view showing another embodiment of the present invention.

FIG. 4 is a cross-sectional view showing another embodiment of the present invention.

FIG. 5 is a cross-sectional view showing another embodiment of the present invention.

FIG. 6 is a cross-sectional view showing another embodiment of the present invention.

FIG. 7 is a cross-sectional view showing another embodiment of the present invention.

FIG. 8 is a cross-sectional view showing another embodiment of the present invention.

FIG. 9 is a longitudinal sectional view of a conventional air turbine drive spindle device.

FIG. 10 is a cross-sectional view of a conventional device.

FIG. 11 is a longitudinal sectional view of a conventional device.

12A is a sectional view taken along line AA in FIG. 11, and FIG. 12B is a sectional view taken along line BB in FIG.

[Explanation of symbols]

 Reference Signs List 1 air turbine drive spindle device 2 housing 2a housing body 2b closing member 3 main shaft 3b thrust plate 4 journal bearing 4a1 journal bearing surface Cj journal bearing gap 5a first thrust bearing 5a1 first thrust bearing surface Csa first thrust bearing gap 5b Thrust bearing part 5b1 Second thrust bearing surface Cs2 Second thrust bearing gap 6 Bearing sleeve 7 Bearing member 11 Recess 21 Brake mechanism 22 Braking air supply unit 23 Pressure chamber 24 Sealing device

Continued on the front page F term (reference) 3J058 AB39 BA01 BA62 CC04 CC78 FA32 3J102 AA02 BA03 CA19 EA02 EB11 FA05 GA07

Claims (11)

[Claims] 1. A main shaft, a journal bearing portion for supporting the main shaft in a radial direction with respect to a fixed member, and a thrust bearing portion for supporting the main shaft in both thrust directions with respect to the fixed member, provided on an outer periphery of the main shaft. An air turbine drive spindle device for applying rotational power to a main shaft by blowing compressed air to a plurality of recesses provided, wherein a brake that generates a braking force by displacing the main shaft in the axial direction by air pressure and contacting the fixed member. An air turbine drive spindle device comprising a mechanism. 2. The air turbine drive spindle device according to claim 1, wherein the brake mechanism includes a pressure chamber facing the main shaft in the axial direction, and a braking air supply unit that supplies air to the pressure chamber. 3. The air turbine drive spindle device according to claim 2, wherein said pressure chamber is sealed with a non-contact seal. 4. The air turbine drive spindle device according to claim 2, wherein the shape of the pressure chamber is axially symmetric with respect to the center axis of the main shaft. 5. The air turbine drive spindle device according to claim 4, wherein the pressure chamber is provided on one or both of the fixed member and the main shaft. 6. The air turbine driving spindle device according to claim 1, wherein at least the thrust bearing portion is a static pressure air bearing that supports the main shaft with a static pressure of air introduced into the thrust bearing gap. 7. An exhaust passage for guiding exhaust of a thrust bearing portion on a side opposite to a displacement direction of a main shaft to an outside, wherein the exhaust passage is shut off during braking by a brake mechanism. Air turbine drive spindle device. 8. An air turbine drive spindle device comprising the non-contact seal according to claim 3 with the thrust bearing gap according to claim 6. 9. The air turbine drive spindle device according to claim 6, wherein air supply to the thrust bearing portion on the main shaft displacement side is shut off during braking. 10. The air turbine drive spindle device according to claim 6, wherein the amount of axial displacement of the main shaft until the main shaft contacts the fixed member during braking is smaller than the width of the thrust bearing gap on the main shaft displacement side. 11. The air turbine drive spindle device according to claim 1, wherein graphite is interposed between a contact portion of the fixed member and the main shaft.