JP2013113179A - Static pressure gas bearing spindle and electrostatic coating apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a static pressure gas bearing spindle capable of highly efficiently rotating a main shaft.SOLUTION: A turbine blade 20 is formed so that the blade height is gradually reduced in a flowing direction of high-presure fluid supplied from a turbine nozzle. An inner wall 21 of a housing facing the turbine blade in the height direction is formed so that it adjacently faces the top of the turbine blade whose blade height is gradually changed.

Description

  The present invention relates to a hydrostatic gas bearing spindle that supplies high-pressure gas to a gas bearing in a housing and rotatably supports the main shaft, and supplies high-pressure gas to turbine blades to rotate the main shaft at high speed, and the hydrostatic gas bearing. The present invention relates to an electrostatic coating apparatus using a spindle.

The static pressure gas bearing spindle supports the spindle in a non-contact state by the pressure of high-pressure gas, so it has less friction loss than other bearing types and is suitable for high-speed spindles. Conventionally, electrostatic coating equipment, grinding machines Used in spindles for small diameter drilling machines.
5 and 6 show a conventional static pressure gas bearing spindle applied to a spindle of an electrostatic coating apparatus.

The hydrostatic gas bearing spindle includes a hollow main shaft 2 and a housing 3 in which a part of the main shaft 2 protrudes and is housed.
The main shaft 2 includes a cylindrical main body 4, a work fixing portion 5 formed at one end of the main body 4, and a flange 6 formed at the other end of the main body 4.
The housing 3 includes a housing main body 7 that accommodates the main spindle body 4 and a plate portion 8 that is integrated with the housing main body 7 via a fastening bolt (not shown) to accommodate the flange 6.

The main spindle body 4 and the flange 6 are supported in a non-contact state by a radial bearing 9 and an axial bearing 10.
The radial bearing 9 and the axial bearing 10 are provided with air supply nozzles 9 a, 9 b, 9 c, 10 a communicating with a gas supply path 11 provided in the housing 3, and supplied from a bearing air supply port 8 a formed in the plate portion 8. The high-pressure gas thus supplied is supplied to the bearing gap between the radial bearing 9 and the axial bearing 10 through the gas supply path 11 and the supply nozzles 9a, 9b, 9c, and 10a. Note that a magnet (not shown) is incorporated in the axial bearing 10, and an appropriate bearing gap is maintained by balancing the repulsion of air and the attractive force of the magnet.

A large number of turbine blades 12 are formed at predetermined intervals in the circumferential direction on the outer peripheral surface of the flange 6 of the main shaft 2.
The plate portion 8 of the housing 3 includes a turbine housing recess 13 that surrounds a large number of turbine blades 12 from the outer periphery and the height direction, and a turbine air intake port that is formed in the axial direction of the plate portion 8 and is supplied with turbine air from the outside. 14, a circumferential groove 15 formed on the outer peripheral side of the inner surface of the plate portion 8 and communicating with the turbine air inlet 14, and an inner surface of the plate portion 8 so as to communicate between the circumferential groove 15 and the turbine housing recess 13. And a plurality of turbine nozzles 16 formed.

A paint diffusion cup 17 is detachably mounted on the work fixing portion 5 of the main shaft 2.
The high pressure gas supplied from the bearing air supply port 8a is supplied to the bearing gap between the radial bearing 9 and the axial bearing 10, so that the main shaft 2 is supported in a non-contact state. The high pressure gas is ejected from the turbine nozzle 16 toward the turbine blade 12, whereby a rotational force is applied to the main shaft 2 and the cup 17 rotates at a high speed. Thus, when the paint is supplied to the cup 17 through a paint supply pipe (not shown), the paint is made fine by the centrifugal force of the cup 17 and is applied.

By the way, many turbine blades 12 formed on the flange 6 are set to have the same height from the blade outer diameter side to the blade inner diameter side, and the turbine of the plate portion 8 surrounding these turbine blades 12. The height of the storage recess 13 is set to be slightly higher than the turbine blade 12.
Then, as shown in FIG. 6, the turbine blades 12 increase the thickness of each turbine blade 12 so that the blade blades of adjacent turbine blades have a blade-to-blade distance C on the blade outer diameter side of the adjacent turbine blades. The inter-blade distance D on the inner diameter side is reduced (D <C). With such an arrangement of the turbine blades 12, the rotational force of the blade outer diameter side of the turbine blades 12 adjacent to the opening of the turbine nozzle 16 is received by the energy of the gas ejected from the turbine nozzle 16. Is an impulse part. Further, by reducing the inter-blade distance D on the blade inner diameter side relative to the inter-blade distance C on the blade outer diameter side, the flow passage cross-sectional area between the adjacent turbine blades 12 and 12 is gradually reduced, and the turbine blade 12 , 12 is increasing the flow velocity of the gas between the blade inner diameter side of the turbine blade 12 (the side away from the opening of the turbine nozzle 16), and jets the gas to the rear in the rotational direction of the main shaft 2. The reaction portion generates a rotational force.

  By the way, when the relation between the blade distance C on the blade outer diameter side of the adjacent turbine blade and the blade distance D on the blade inner diameter side is set to D <C as described above, the thickness of the turbine blade 2 increases. The main shaft 2 having an increased mass has a problem in that the rotation efficiency is deteriorated because the acceleration / deceleration time becomes longer due to the increase of the moment of inertia. Further, the increase in the mass of the turbine blades increases the stress due to the centrifugal force, and the rotational speed must be suppressed.

  Therefore, for example, as described in Patent Document 1, the thickness of each turbine blade (referred to as a rotor blade in Patent Document 1) is not increased (no reaction portion is provided), and the front of the turbine blade in the rotation direction is increased. A front plane portion is provided on the outer peripheral portion (blade outer diameter side) of the first surface facing the front side, and a front surface portion is provided on the inner peripheral portion (blade inner diameter side) of the first surface. The technology to rotate the main shaft with high efficiency by suppressing energy loss without causing turbulence in the gas flow by configuring the gas ejection direction from the nozzle for gas to be substantially parallel. Are known.

JP 2006-300024 A

  However, in Patent Document 1, a front plane portion that is substantially parallel to the gas ejection direction must be formed on the first surface of a large number of turbine blades with high accuracy, which is complicated in the formation of turbine blades. Since a process is required, the manufacturing cost may increase. Compared to the structure shown in FIG. 6 in which the distance between the blades D on the blade inner diameter side of the adjacent turbine blade is made smaller than the distance C between the blades on the blade outer diameter side of the adjacent turbine blade, and the reaction portion is provided. The rotational efficiency of the main shaft is reduced.

  Therefore, the present invention has been made paying attention to the above-mentioned unsolved problems of the conventional example, and a static pressure gas bearing spindle and a static pressure gas bearing spindle capable of rotating the spindle with high efficiency and reducing the manufacturing cost. The object is to provide an electropainting device.

  In order to achieve the above object, a hydrostatic gas bearing spindle according to claim 1 according to the present invention comprises a main shaft, a housing that houses the main shaft, and a high-pressure gas supplied so that the main shaft is not in contact with the housing. A plurality of turbine blades disposed in the housing surrounding the plurality of turbine blades, a gas bearing rotatably supported by the plurality of turbine blades, a plurality of turbine blades arranged in a circumferential direction of the main shaft, and the plurality of turbine blades. A hydrostatic gas bearing spindle including a turbine nozzle that ejects high-pressure gas toward the turbine to rotate the main shaft, and a flow direction of the high-pressure fluid supplied from the turbine nozzle to the plurality of turbine blades Of the housing that is formed so that the blade height gradually decreases toward the turbine and that faces the plurality of turbine blades from the height direction. It was formed so as to face in proximity to the top of the turbine blade which blade height is gradually changed.

According to a second aspect of the present invention, in the hydrostatic gas bearing spindle according to the first aspect, the distance between the blades on the inlet side of the high-pressure fluid of the pair of turbine blades adjacent in the circumferential direction, and the pair of turbine blades The distance between the blades on the outlet side of the high-pressure fluid was set to the same dimension.
An electrostatic coating apparatus according to a third aspect includes the static pressure gas bearing spindle according to the first or second aspect.

  According to the static pressure gas bearing spindle and the electrostatic coating apparatus according to the present invention, the plurality of turbine blades are formed so that the blade height gradually decreases in the direction in which the high-pressure fluid supplied from the turbine nozzle flows. And the inner wall of the housing that faces the plurality of turbine blades from the height direction is formed so as to face the top of the turbine blade, the blade height of which gradually changes, so that the high-pressure fluid Since the flow path cross-sectional area gradually decreases in the direction in which the gas flows, when the gas supplied from the turbine nozzle passes between a large number of turbine blades, a large rotational force can be generated in the main shaft. The spindle can be rotated with high efficiency.

It is sectional drawing which shows the static pressure gas bearing spindle which concerns on this invention. It is the II arrow directional view of FIG. It is a figure which shows the inner wall of the housing which has covered the shape of the turbine blade which concerns on this invention, and the turbine blade from a height direction. It is a perspective view which shows the shape of the turbine blade which concerns on this invention. It is sectional drawing which shows the conventional static pressure gas bearing spindle. It is the II-II arrow directional view of FIG.

DESCRIPTION OF EMBODIMENTS Hereinafter, modes for carrying out the present invention (hereinafter referred to as embodiments) will be described in detail with reference to the drawings.
1 to 4 show a hydrostatic gas bearing spindle according to the present invention applied to a spindle of a rotary atomizing electrostatic coating machine. In addition, the same code | symbol is attached | subjected to the component same as the structure shown in FIG.5 and FIG.6, and the description is abbreviate | omitted.

A large number of turbine blades 20 are formed at predetermined intervals in the circumferential direction on the outer peripheral surface of the flange 6 of the main shaft 2 of the present embodiment.
As shown in FIGS. 3 and 4, each turbine blade 20 has a tall outer diameter portion 20a and a small inner diameter so that the height h2 on the blade inner diameter side is smaller than the height h1 on the blade outer diameter side. The part 20b and the inclined part 20c are formed between them. The thickness of each turbine blade 20 is smaller than that of the turbine blade 12 shown in FIG. 6, and the blade-to-blade distance A on the blade outer diameter side of the adjacent turbine blades 20, 20. And the distance B between the blades on the blade inner diameter side are set to the same dimension (A = B).

The plate portion 8 that is integrated with the housing body 7 and accommodates the flange 6 is formed with a turbine accommodating recess 21 that surrounds a large number of turbine blades 20 from the outer periphery and the height direction.
And the inner wall of the turbine accommodating recess 21 facing the numerous turbine blades 20 from the height direction is close to the tall outer diameter portion 20a of the turbine blade 20 as shown in FIG. An annular tall outer diameter side inner wall 21a, a circular inner diameter lower inner diameter wall 21b facing the lower inner diameter portion 20b of the turbine blade 20, and a tall outer diameter inner wall 21a and a lower height. An annular inclined inner wall 21c is provided between the inner diameter side inner walls 21b and facing the inclined portion 20a of the turbine blade 20 in close proximity.

  In the static pressure gas bearing spindle of the present embodiment, the high pressure gas supplied from the bearing air supply port 8a is supplied to the bearing gap between the radial bearing 9 and the axial bearing 10 so that the main shaft 2 is supported in a non-contact state. The high pressure gas is ejected from the turbine nozzle 16 toward the blade outer shape side of the large number of turbine blades 20, whereby a rotational force is applied to the main shaft 2 and the cup 17 rotates at a high speed. As a result, when the paint is supplied to the cup 17 through a paint supply pipe (not shown), the paint is made fine by the centrifugal force of the cup 17 to be applied.

  Here, the configuration in which the plurality of turbine blades according to the present invention are formed such that the blade height gradually decreases in the direction in which the high-pressure fluid supplied from the turbine nozzle flows, The inner wall of the housing corresponding to the low inner diameter portion 20b and the inclined portion 20c and facing the turbine blade of the present invention from the height direction is the tall outer diameter inner wall 21a, the lower inner diameter inner wall 21b, and the inclined inner wall 21c. It corresponds to.

Next, in this embodiment, an operation when high-pressure gas is ejected from the turbine nozzle 16 toward the turbine blade 20 will be described.
Many turbine blades 20 form a tall outer diameter portion 20a, an inclined portion 20c, and a lower inner diameter portion 20b from the blade outer diameter side toward the blade inner diameter side, and the direction in which the gas supplied from the turbine nozzle 16 flows. And the inner wall of the turbine housing recess 21 facing the numerous turbine blades 20 from the height direction is close to the tall outer diameter portion 20a. The inner wall 21a, which is opposed to the tall outer diameter, the inner wall 21c, which is opposed to the inclined portion 20c, and the inner wall 21b, which is opposed to the lower inner diameter portion 20b. And. As a result, the cross-sectional area of the flow path surrounded by the adjacent turbine blades 20 and 20, the outer peripheral surface of the flange 6 and the turbine housing recess 21 is gradually set smaller from the blade outer diameter side toward the blade inner diameter side. ing.

The blade outer diameter side (the tall outer diameter portion 20a) of the large number of turbine blades 20 receives the energy of the high-pressure gas supplied from the turbine nozzle 16 as an impulse portion and generates a rotational force with respect to the main shaft 2. .
Further, the flow passage cross-sectional area formed by being surrounded by the adjacent turbine blades 20, 20, the outer peripheral surface of the flange 6, and the turbine housing recess 21 gradually becomes smaller from the blade outer diameter side toward the blade inner diameter side. Therefore, the flow velocity of the gas passing between the numerous turbine blades 20 and moving toward the blade inner diameter side increases again. As a result, the blade inner diameter side (the inner wall 21b on the lower inner diameter side) of the large number of turbine blades 20 ejects a gas having an increased flow velocity to the rear in the rotation direction of the main shaft 2, and generates a large rotational force on the main shaft 2 as a reaction part. To do.

The effect of this embodiment will be described.
According to the static pressure gas bearing spindle of the present embodiment, the flow passage cross-sectional area formed by being surrounded by the adjacent turbine blades 20, 20, the outer peripheral surface of the flange 6, and the turbine housing recess 21 is the blade outer diameter side. Therefore, when the gas supplied from the turbine nozzle 16 passes between a large number of turbine blades 20, a large rotational force is generated on the main shaft 2. Further, since the inter-blade distance A on the blade outer diameter side and the inter-blade distance B on the blade inner diameter side of the adjacent turbine blades 20 and 20 are set to the same dimension, and the thickness of each turbine blade 20 is set thin, the spindle 2 And the moment of inertia of the main shaft 2 is reduced. Therefore, when the gas supplied from the turbine nozzle 16 passes between a large number of turbine blades 20, a large rotational force is applied to the main shaft 2 from the impulse and reaction portions of the large number of turbine blades 20, and the moment of inertia is increased. Since the reduced main shaft 2 rotates, the main shaft 2 can be rotated with high efficiency.

  In addition, the large number of turbine blades 20 of the present embodiment are not subjected to special processing for suppressing energy loss, and the blade-to-blade distance A on the blade outer diameter side and the blade inner diameter side of the adjacent turbine blades 20, 20. Since it is set as the simple structure which set the distance B between blades to the same dimension, when forming the turbine blade 20, a complicated process is not required and reduction of manufacturing cost can be aimed at.

  DESCRIPTION OF SYMBOLS 2 ... Main shaft, 3 ... Housing, 4 ... Main shaft main body, 5 ... Work fixing | fixed part, 6 ... Flange, 7 ... Housing main body, 8 ... Plate part, 8a ... Bearing air supply port, 9 ... Radial bearing, 9a, 9b, 9c , 10a ... Air supply nozzle, 10 ... Axial bearing, 11 ... Gas supply path, 14 ... Turbine air inlet, 15 ... Circumferential groove, 16 ... Turbine nozzle, 17 ... Cup, 20 ... Turbine blade, 20a ... Tall Outer diameter portion, 20b ... Lower inner diameter portion, 20c ... Inclined portion, 21 ... Turbage recess, 21a ... Tall outer diameter side inner wall, 21b ... Lower inner diameter side inner wall, 21c ... Inclined side inner wall, A, B ... Blade Distance

Claims (3)

A main shaft, a housing that houses the main shaft, a gas bearing that rotatably supports the main shaft in a non-contact manner with respect to the housing by supplying high-pressure gas, and a plurality of circumferentially arranged portions of the main shaft A static pressure provided with a turbine blade, and a turbine nozzle that is provided inside the housing surrounding the plurality of turbine blades and jets high-pressure gas toward the plurality of turbine blades to rotate the main shaft. In the gas bearing spindle,
The plurality of turbine blades are formed such that the blade height gradually decreases in the direction in which the high-pressure fluid supplied from the turbine nozzle flows,
The inner wall of the housing facing the plurality of turbine blades from the height direction is formed so as to face the top of the turbine blade where the blade height is gradually changing. Hydrostatic gas bearing spindle.   The distance between the blades on the inlet side of the high-pressure fluid of the pair of turbine blades adjacent in the circumferential direction and the distance between the blades on the outlet side of the high-pressure fluid of the pair of turbine blades are set to the same dimension. The hydrostatic gas bearing spindle according to claim 1.   An electrostatic coating apparatus comprising the static pressure gas bearing spindle according to claim 1.

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