JP4176814B2 - Air turbine drive spindle device - Google Patents

Description

  The present invention relates to an air turbine drive spindle device that blows compressed air onto a main shaft to provide rotational power, and can be used as a spindle device for a hole drilling machine, a precision machine, an electrostatic coating machine, or the like.

  8 and 9 illustrate the above-described conventional spindle device using a static pressure air bearing. This spindle device has an air turbine drive system, that is, a plurality of recesses 110 provided on the outer periphery of a thrust plate 30b provided on the main shaft 30, and a plurality of turbine nozzles 120 opened in a tangential direction at positions facing the recesses 110. The compressed air supplied from the turbine air supply port 140 through the turbine supply passage 150 in the circumferential direction is blown from the turbine nozzle 120 to the wall surface 110b in the radial direction of the recess 110 to rotate the main shaft 30. is there. The air that gives 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 supported by a journal bearing portion 40 and thrust bearing portions 50a and 50b so as to be rotatable with respect to a stationary member such as the housing 20 in the radial direction and the thrust direction. The two bearing portions 40, 50a and 50b here are hydrostatic air bearings that support the main shaft 30 in a non-contact manner with the static pressure of compressed air introduced into minute journal bearing gaps and thrust bearing gaps.
No. 8-5373

  FIG. 10 schematically shows a conventional air flow in the recess 110. The air blown from the turbine nozzle 120 to the recess 110 hits the wall surface 110b in the radial direction as indicated by a broken line in the figure. After a rotational force is applied to the main shaft 30, it is exhausted separately on both sides in the axial direction.

  However, since the air flows separately in the left and right directions in the recess 110 in this way, the air flow is likely to be disturbed near the diversion portion (near B portion in the figure), which causes energy loss.

  Therefore, an object of the present invention is to provide an air turbine drive spindle device having higher turbine efficiency by smoothing the flow of compressed air and reducing energy loss.

In order to achieve the above object, in the present invention, a main shaft, a bearing portion that rotatably supports the main shaft, and an outer peripheral surface of the main shaft, and a plurality of symmetrical on both sides in the axial direction across a circumferential center line. A turbine nozzle provided with a recess and a turbine nozzle that is provided opposite to the recess and blows compressed air to the recess to provide rotational power to the main shaft. The recess and the turbine nozzle are arranged in a double row, and the center line of the double row of recesses were parallel, each turbine nozzle, nozzle spacing in the axial direction is arranged to be inclined with respect to the direction in the recess of the center line to reduce an inner diameter side, of the turbine nozzle of a double row, from one turbine nozzle, double An air flow is blown to one of the recess rows of the rows, an air flow is blown to the other recess row from the other turbine nozzle, and the air flows that flow into the recesses are discharged in directions away from each other in the axial direction. Made Thereby, since the flow of the compressed air in the concave portion is a single flow, it is possible to avoid the turbulence of the flow associated with the conventional diversion and the energy loss associated therewith. Further, mutual interference between the air flow supplied to one of the recess rows and the air flow supplied to the other recess row can be avoided, and the air flow can be further prevented from being disturbed.

  If the number of turbine nozzles on the one side and the other side in the axial direction are the same, the axial component force acting on the main shaft can be offset by the compressed air pressure blown to the recess, and the axial load on the main shaft can be balanced. Can do.

  In each of the above configurations, the bearing portion has a journal bearing portion that supports the main shaft in a non-contact manner in the radial direction by the static pressure of compressed air introduced into the journal bearing clearance, and a thrust shaft that is thrust by the static pressure of compressed air introduced into the thrust bearing clearance. It can be constituted by a thrust bearing portion that is supported in a non-contact manner in the direction.

  According to the present invention, the flow of compressed air in the recess is a single flow. Therefore, it is possible to avoid the turbulent flow associated with the diversion and the energy loss associated therewith as in the prior art, and to efficiently apply the rotational power to the main shaft.

  When the bearing portion is composed of a journal bearing portion and a thrust bearing portion made of a static pressure air bearing, compressed air is used for supplying air to the bearing. Therefore, even when an air turbine is used as a drive source for the spindle, the compressed air for the air turbine can be easily secured by using the compressed air for supplying the bearing air. Further, the exhaust on the air turbine side and the exhaust on the bearing side can be performed at a common exhaust port, and the space in the housing can be used effectively. Since the air turbine generates little heat, it is convenient as a power source even when a hydrostatic air bearing that has a small bearing clearance and is easily affected by thermal deformation is used for the bearing portion as described above. In addition, since an air turbine has a smaller mass added to a rotating body than an electric motor or the like, high-speed rotation can be easily realized by a combination with a hydrostatic air bearing having a small bearing loss.

  Hereinafter, embodiments of the present invention will be described with reference to FIGS.

[Reference example]
As shown in FIG. 1, an air turbine drive spindle apparatus 1 according to the present invention inserts a main shaft 3 including a shaft portion 3 a and a thrust plate 3 b provided at the tip thereof into an inner peripheral portion of a housing 2. Is supported by a bearing portion, for example, a journal bearing portion 4 formed of a static pressure air bearing, and thrust bearing portions 5a and 5b in a non-contact manner so as to be rotatable in a radial direction and a thrust direction. The bearing portions 4, 5a and 5b may have a bearing structure other than the static pressure air bearing.

  The housing 2 includes a cylindrical housing body 2a and a closing member 2b that closes an opening at one end thereof. The housing main body 2a includes 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 through a minute journal bearing clearance. A flange portion 6a extending to the outer diameter side is formed at one end portion of the bearing sleeve 6, and the first thrust bearing surface is opposed to one end surface of the thrust plate 3b via a minute thrust bearing clearance on the end surface of the flange portion 6a. 5a1 is formed. A bearing member 7 is attached to the portion of the closing member 2b facing the thrust plate 3b, and the second end surface of the bearing member 7 is opposed to the other end surface of the thrust plate 3b via a minute thrust bearing clearance. A thrust bearing surface 5b1 is formed. The journal bearing surface 4a1 and the first and second thrust bearing surfaces 5a1, 5b1 are provided with fine bearing nozzles 9a, 9b at a plurality of locations, and supply air through an air supply passage (not shown). When compressed air is supplied to the bearing nozzles 9a and 9b from the power source (both not shown), the compressed air is introduced into the journal bearing clearance and the thrust bearing clearance, and the shaft portion 3a of the main shaft 3 is radially provided in each bearing clearance. The journal bearing 4 is supported in a non-contact manner in the direction, and the thrust bearing portions 5a, 5b are configured to support the thrust plate 3b of the main shaft 3 in a non-contact manner in both thrust directions.

  The driving method of the main shaft 3 is an air turbine driving method similar to that of the conventional spindle device shown in FIGS. 8 and 9, and a plurality of recesses 11 are provided on the outer periphery of the thrust plate 3b of the main shaft 3 as shown in FIG. At the same time, a plurality of turbine nozzles 12 are arranged at positions facing the recesses 11, and the main shaft 3 is rotated by blowing compressed air from each turbine nozzle 12 to the recesses 11 of the thrust plate 3b. In the present embodiment, the turbine nozzle 12 is provided on an annular nozzle member 13 fixed to the inner peripheral surface of the large-diameter portion 2a1 of the housing body 2a so as to face 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 15 provided on the inner peripheral surface of the large diameter portion 2a1 so as to face the nozzle member 13. Done. The annular groove 15 may be provided on the outer peripheral surface of the nozzle member 13.

  Each recess 11 has side surfaces 11a on both sides in the axial direction, and a substantially radially extending wall surface (pressure-receiving surface) 11b provided on one side in the circumferential direction, which sandwich a circumferential center line O. It is formed symmetrically on both sides in the axial direction. The pressure receiving surface 11b is a curved surface (for example, an arc surface) having a concave cross section. The bottom of the recess 11, that is, the portion 11c from the inner diameter end of the pressure receiving surface 11b to the outer peripheral surface of the thrust plate 3b is a flat surface that is substantially parallel to the direction of the turbine nozzle 12 when the pressure receiving surface 11b faces the turbine nozzle 12. It has become.

  As shown in FIGS. 1 and 3, in the present invention, the turbine nozzle 12 is provided at a position offset in the axial direction with respect to the recess 11. Due to such an offset, the flow of the compressed air in the recess 11 becomes a single U-shaped flow as shown by a broken line in FIG. Accordingly, it is possible to avoid the flow disturbance (energy loss) associated with the diversion as in the prior art, and to efficiently apply the rotational power to the main shaft 3. The air flow that gives rotational power to the main shaft 3 is discharged out of the housing 2 through the exhaust ports 16a and 16b, particularly the exhaust port 16a on the downstream side of the single flow.

  In order to further reduce the turbulence of the flow in the recess 11, (1) the diameter D of the turbine nozzle 12 is set to 1/2 or less of the axial width X of the recess 11 [D ≦ X / 2], (2) the recess The offset amount L between the center line O of 11 and the nozzle center line P of the turbine nozzle 12 is not less than 1/2 of the nozzle diameter D, and 1/2 of the difference between the axial width X of the recess 11 and the nozzle diameter D. [D / 2 ≦ L ≦ (X−D) / 2] is preferable as follows. Further, the offset direction of the turbine nozzle 12 may be any direction in the axial direction, and may be offset in the direction opposite to the illustrated direction if structurally possible. In addition, as shown in FIG. 4, the offset direction of each turbine nozzle 12 (shown by a broken line) can be made different between the one side and the other side in the axial direction. If the offset amount and the number of the nozzles 12 are made the same, the axial component force acting on the pressure receiving surface 11b can be canceled, and the axial load of the main shaft 3 can be balanced.

5 and 6 show another embodiment of the present invention. This air turbine drive spindle device 1 ′ forms a double row (two rows in this embodiment) with the recesses 11 spaced apart in the axial direction on the outer periphery of the thrust plate 3b, and correspondingly, the compressed air is applied to the recesses 11 Are arranged in a double row, and the other configuration is basically the same as that shown in FIG. 1 (the same reference numerals are assigned to the common members, and duplicate descriptions are omitted). . Also in this embodiment, as in FIGS. 1 and 3, the rows of turbine nozzles 12 are offset in the axial direction with respect to the corresponding recesses 11 (the offset amount L is equal in both rows). It is possible to reduce the energy loss of the compressed air at. At this time, if the double-row turbine nozzles 12 are offset to the axial approach side, as shown in FIG. 6 , the mutual interference between the air flow flowing through one recess 11 and the air flow flowing through the other recess 11 Thus, the turbulence of the air flow can be suppressed and the rotational power can be applied to the main shaft 3 more efficiently. In this case, if the number of turbine nozzles 12 in both rows is the same, the axial load of the main shaft 3 can be balanced as in the case of FIG.

[Example]
The above is the case where the supply direction of compressed air from the turbine nozzle 12 (the direction of the nozzle center P) is parallel to the center line O of the recess 11, but as shown in FIG. Even if it is arranged to be inclined with respect to the center line O, a single flow can be realized in the recess 11 and the same effect as described above can be obtained. This configuration can also be applied to the double-row air turbine drive spindle apparatus 1 'shown in FIG. 5, in which case, as shown in FIG. 11, in order to prevent mutual interference between the two air flows, the turbine nozzle 12 It is desirable that the inclination direction is such that the interval between the nozzles 12 in the axial direction is reduced on the inner diameter side.

It is sectional drawing of an air turbine drive spindle apparatus. It is sectional drawing in the AA line in FIG. It is an expanded sectional view which shows the flow of the air flow in a recessed part. It is an enlarged plan view which shows other embodiment. It is sectional drawing which shows other embodiment. It is an expanded sectional view which shows the flow of the air flow in the recessed part in the said embodiment. It is an expanded sectional view showing other embodiments. It is sectional drawing of the conventional air turbine drive spindle apparatus. It is sectional drawing in the AA line in FIG. It is an expanded sectional view which shows the flow of the air flow in the recessed part in a conventional apparatus. It is an expanded sectional view showing an embodiment of the present invention.

Explanation of symbols

1 Air turbine drive spindle device
1 'Air turbine drive spindle device 2 Housing 3 Spindle
3b Thrust plate 4 Journal bearing
5a Thrust bearing
5b Thrust bearing
11 Recess
12 Turbine nozzle D Nozzle diameter L Offset O Recess center line P Nozzle center X Recess axial width

Claims (2)

A main shaft, a bearing portion that rotatably supports the main shaft, a plurality of concave portions that are provided on the outer peripheral surface of the main shaft, are symmetrical on both sides in the axial direction across the circumferential center line, and are opposed to the concave portions; In what has a turbine nozzle that blows compressed air to the recess and gives rotational power to the main shaft,
The recesses and the turbine nozzles are arranged in a double row, the center lines of the recesses in the double row are parallel, and each turbine nozzle is inclined with respect to the center line of the recesses in the direction in which the axial nozzle interval is reduced on the inner diameter side. The air flow is blown from one turbine nozzle of the double-row turbine nozzles to one concave row of the double-row concave portions, and the air flow is blown from the other turbine nozzle to the other concave row. An air turbine drive spindle device characterized in that the air flow flowing into the recess is discharged in a direction away from each other in the axial direction.   The above-mentioned bearing part supports the main shaft in a non-contact manner in the radial direction by the static pressure of the compressed air introduced into the journal bearing clearance, and the main shaft is not contacted in the thrust direction by the static pressure of the compressed air introduced into the thrust bearing clearance. The air turbine drive spindle device according to claim 1, further comprising a thrust bearing portion to be supported.

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