JP5888663B2 - Spindle motor - Google Patents

Description

  The disclosed embodiment relates to a spindle motor that supports a main shaft in a non-contact state.

  In Patent Document 1, the main shaft (rotary spindle) housed in a housing, two radial bearings (radial air bearings) that support the radial direction of the main shaft, and the axial direction of a thrust disk (thrust bearing flange) provided on the main shaft A spindle unit having a double-sided thrust bearing (thrust air bearing) arranged so as to sandwich both sides and supporting the thrust direction of the main shaft is described.

JP 2004-25667 A

  A spindle motor is often used with a housing assembled to a production machine with high positioning accuracy. For this reason, it is desired that the spindle motor can be disassembled and maintained without removing the housing from the production machine. However, as in the above prior art, in a configuration in which radial bearings and thrust bearings are provided on both axial sides of the thrust disk in order to suppress interference with the housing due to rotational shake of the main shaft, the work of extracting the main shaft from the additional side of the housing is not performed. It was complicated.

  The present invention has been made in view of such problems, and an object of the present invention is to provide a spindle motor that can suppress interference between a main shaft and a housing and can easily perform a disassembly operation for maintenance.

In order to solve the above problems, according to one aspect of the present invention, a housing having a shaft hole that has an opening on the load side and communicates with the anti-load side, and a thrust disk, A main shaft that is accommodated substantially coaxially, a radial bearing that is accommodated in the shaft hole and that supports the main shaft in a radial direction, and is accommodated in the shaft hole. A thrust bearing configured to perform support in a thrust direction in a non-contact manner; a rotor provided on the main shaft; and a stator provided on the inner peripheral side of the shaft hole so as to face the rotor. a spindle motor for chromatic and motor, and the thrust bearing and the radial bearing is arranged on both the respective load side and the anti-load side of the thrust disk, the opening is a load side of said thrust disk Wherein the arrangement has been said radial bearing and said thrust bearing, said removably configured to the main shaft, including the thrust disk in the axial direction, the thrust bearing and the radial bearing, and the main shaft to eject fluid The spindle motor is configured as a fluid bearing that supports a thrust disk, and the spindle motor is fixed to the load side of the housing and the radial bearing so as to cover the load side of the radial bearing arranged on the most load side, and is attached to the shaft hole. The plate further includes a communication hole that communicates, and the radial bearing disposed at a load side of the thrust disk and at least one of the thrust bearing and the plate are between the thrust disk and the radial bearing. and an exhaust bypass passage for exhausting the fluid to the vicinity of the opening, the spindle motor There are applied.

  According to the present invention, the interference between the main shaft and the housing can be suppressed, and the disassembly work for maintenance can be easily performed.

It is a longitudinal section showing the whole spindle motor composition concerning an embodiment. It is another longitudinal cross-sectional view showing the whole spindle motor structure concerning an embodiment. It is a longitudinal section showing the whole spindle motor composition concerning a comparative example. It is explanatory drawing for demonstrating the replacement | exchange procedure of a bearing.

  Hereinafter, an embodiment will be described with reference to the drawings.

<Overall configuration of spindle motor of this embodiment>
First, the overall configuration of the spindle motor according to the present embodiment will be described with reference to FIGS. 1 and 2. 1 and 2 are longitudinal sectional views at different angles around the central axis of the same spindle motor. In FIG. 1, a part of the main shaft is represented by a longitudinal section, and in FIG. 2, the main shaft is represented by an external appearance. In the following description, the right side in FIGS. 1 and 2 will be described as the load side on which the machining tool is mounted, and the left side as the anti-load side.

  As shown in FIGS. 1 and 2, the spindle motor 1 according to the present embodiment is housed in a cylindrical housing 2 and a shaft hole 2A communicating with the center of the housing 2, and is thrust slightly toward the load side from the center. It has a main shaft 3 provided with a disk 3a and a motor 4 provided on the non-load side. The motor 4 includes a rotor 4a provided on the opposite side of the main shaft 3 and a stator 4b provided on the inner peripheral side of the shaft hole 2A of the housing 2 so as to face the rotor 4a via a sleeve 5. Have. A back plate 6 having a discharge hole 6 a is provided on the opposite side of the housing 2. On the load side of the housing 2, a front plate 9 having a communication hole 9 a that communicates with the shaft hole 2 </ b> A and penetrates the main shaft 3 is provided. The shaft hole 2A of the housing 2 has a shaft hole small diameter portion 2a having a small inner diameter in the non-load side portion of the range on the load side of the motor 4, and a shaft hole large diameter portion 2b having a large inner diameter on the load side portion. Yes. The main shaft 3 and its thrust disk 3a are accommodated in a substantially coaxial arrangement in which the respective central axes substantially coincide with each other inside the shaft hole small diameter portion 2a and the shaft hole large diameter portion 2b of the shaft hole 2A.

  The spindle motor 1 includes a radial bearing 10 that performs non-contact support in the radial direction of the main shaft 3 in the axial direction of the main shaft 3 in the vicinity of the motor 4, and the radial direction and thrust of the main shaft 3 on the non-load side of the thrust disk 3a. A non-contact radial thrust bearing 20 that performs non-contact support in both directions of the thrust direction of the disk 3a, and non-contact support in both the radial direction of the main shaft 3 and the thrust direction of the thrust disk 3a on the load side of the thrust disk 3a And a load side radial thrust bearing 30. The non-load-side radial thrust bearing 20 is integrally provided with a radial bearing portion 20A that supports the main shaft 3 in the radial direction in a non-contact manner and a thrust bearing portion 20B that supports the thrust disc 3a in a thrust direction in a non-contact manner. ing. The load-side radial thrust bearing 30 is integrally provided with a radial bearing portion 30A that supports the main shaft 3 in the radial direction in a non-contact manner and a thrust bearing portion 30B that supports the thrust disc 3a in the thrust direction in a non-contact manner. Yes.

  The bearings 10, 20, and 30 are fluid bearings that are supported in a non-contact manner by ejecting fluid and forming a fluid film between the main shaft 3 and the thrust disk 3a. In the present embodiment, a case where compressed air is used as a fluid will be described as an example. However, the present invention is not limited to this, and other fluids such as high-pressure water and high-pressure oil may be used.

  As shown in FIG. 1, the housing 2 is provided with an air supply passage 7 for supplying compressed air to the bearings 10, 20, and 30 and an exhaust passage 8 for exhausting air. The air supply passage 7 and the exhaust passage 8 are provided at appropriate locations (one location or multiple locations) in the circumferential direction of the housing 2. In the example shown in FIG. 1, the air supply passage 7 and the exhaust passage 8 are disposed to face each other in the circumferential direction. The supply passage 7 corresponds to an example of a first supply path described in the claims.

<Configuration of radial bearing>
Next, the configuration of the radial bearing 10 will be described. The radial bearing 10 is fitted on the inner peripheral side of the shaft hole small diameter portion 2 a of the housing 2. The radial bearing 10 includes a bearing main body 11 and a radial bearing sleeve 12 that is provided on the inner peripheral side of the bearing main body 11 by bonding or the like and is disposed to face the surface of the main shaft 3. The bearing body 11 is made of a highly rigid material (for example, stainless steel), and the radial bearing sleeve 12 is made of a highly self-lubricating material (for example, carbon). The bearing body 11 is provided with air supply passages 13 a and 13 b communicating with the air supply passage 7, and the radial bearing sleeve 12 communicates with the air supply passages 13 a and 13 b, respectively, on the surface of the main shaft 3. Air supply nozzles 14a and 14b for ejecting compressed air are provided. The air supply passage 13 and the air supply nozzle 14 are provided at a plurality of locations in the circumferential direction. In the example shown in FIG. 1, the air supply passage 13 and the air supply nozzle 14 are provided at two positions in the axial direction, but may be one position or three or more positions. Further, O-rings 52 are fitted on both sides of the air supply passages 13a and 13b in the axial direction on the outer peripheral surface of the bearing body 11 of the radial bearing 10, and the air supply passage 7 and the air supply passages 13a and 13b are connected. The communication part is sealed.

<Configuration of the anti-load side radial thrust bearing>
Next, the configuration of the anti-load side radial thrust bearing 20 will be described. The anti-load side radial thrust bearing 20 has a radial bearing portion 20A fitted on the inner peripheral side of the small diameter portion 2a of the shaft hole of the housing 2, and the thrust bearing portion 20B on the load side of the radial bearing portion 20A. It is fitted to the inner peripheral side of the large diameter portion 2b. The anti-load side radial thrust bearing 20 includes a bearing body portion 21 having a substantially L-shaped cross-section provided across the radial bearing portion 20A and the thrust bearing portion 20B, and the inner periphery of the bearing body portion 21 in the radial bearing portion 20A. The radial bearing sleeve 22 is disposed on the side of the main shaft 3 by bonding or the like, and is provided on the inner peripheral side of the bearing body 21 in the thrust bearing portion 20B by bonding or the like. And a thrust bearing sleeve 23 having a substantially L-shaped cross-sectional view disposed opposite to the surface of the disk 3a. Similar to the radial bearing 10, the bearing body 21 is made of a highly rigid material (for example, stainless steel), and the radial bearing sleeve 22 and the thrust bearing sleeve 23 are made of a highly self-lubricating material (for example, carbon). It consists of

  The radial bearing portion 20A of the bearing body 21 is provided with air supply passages 24a and 24b communicating with the air supply passage 7, and the radial bearing sleeve 22 communicates with the air supply passages 24a and 24b, respectively. Two air supply nozzles 25 a and 25 b for ejecting compressed air are provided on the surface of the main shaft 3. The thrust bearing portion 20B of the bearing body 21 is provided with an air supply passage 24c communicating with the air supply passage 7. The thrust bearing sleeve 23 communicates with the air supply passage 24c, and the thrust disk. An air supply nozzle 25c for ejecting compressed air is provided on the surface of 3a. The air supply passage 24 and the air supply nozzle 25 are provided at a plurality of locations in the circumferential direction. In the example shown in FIG. 1, the air supply passage 24 and the air supply nozzle 25 are provided at two locations in the axial direction in the radial bearing portion 20 </ b> A, but may be one location or three or more locations. Further, although the air supply nozzle 25c is provided at one place in the radial direction in the thrust bearing portion 20B, it may be two or more places. An O-ring 52 is fitted on the outer peripheral surface of the radial bearing portion 20A of the bearing body portion 21 in the same arrangement as the radial bearing 10, and the communication between the air supply passage 7 and the air supply passages 24a and 24b is performed. The part is sealed.

  As shown in FIG. 2, through-holes 29 are provided at a plurality of locations in the circumferential direction of the thrust bearing portion 20B, and a plurality of fixing bolts 50 respectively penetrate the through-holes 29 in the axial direction of the main shaft 3, The anti-load-side radial thrust bearing 20 is fixed to the housing 2 by being screwed into a screw hole (not shown) of the housing 2.

<Spacer configuration>
Next, the configuration of the spacer 40 will be described. A spacer 40 is provided on the load side of the thrust bearing portion 20 </ b> B of the anti-load side radial thrust bearing 20. As shown in FIG. 2, through holes 41 for the fixing bolts 50 are provided at a plurality of locations in the circumferential direction of the spacer 40 (positions corresponding to the through holes 29). The spacer 40 is disposed on the outer peripheral side of the thrust disk 3a by being fixed to the load side of the thrust bearing portion 20B by a fixing bolt 50 penetrating the through hole 41. As shown in FIG. 1, the spacer 40 has an air supply passage 42 that communicates with the air supply passage 24 c of the thrust bearing portion 20 </ b> B and penetrates the spacer 40 in the axial direction.

<Configuration of load side radial thrust bearing>
Next, the configuration of the load side radial thrust bearing 30 will be described. A load-side radial / thrust bearing 30 is provided on the load side of the spacer 40. In the load side radial thrust bearing 30, both the radial bearing portion 30 </ b> A and the thrust bearing portion 30 </ b> B are fitted to the inner peripheral side of the shaft hole large diameter portion 2 b of the housing 2. The load-side radial thrust bearing 30 includes a bearing body 31 having a substantially rectangular shape in cross section provided across the radial bearing 30A and the thrust bearing 30B, and an inner peripheral side of the bearing body 31 in the radial bearing 30A. A radial bearing sleeve 32 that is provided by bonding or the like and disposed opposite to the surface of the main shaft 3, and is provided on the inner peripheral side of the bearing main body 31 in the thrust bearing portion 30B by bonding or the like. The main shaft 3 and the thrust disk 3a And a thrust bearing sleeve 33 having a substantially L-shaped cross-sectional view, which is disposed so as to face the surface. Similar to the radial bearing 10 and the anti-load-side radial thrust bearing 20, the bearing body 31 is made of a highly rigid material (for example, stainless steel), and the radial bearing sleeve 32 and the thrust bearing sleeve 33 are self-supporting. It is made of a material having high lubricity (for example, carbon).

  The radial bearing portion 30A portion of the bearing body 31 is provided with air supply passages 34a and 34b communicating with the air supply passage 42 of the spacer 40, and the radial bearing sleeve 32 is provided with air supply passages 34a and 34b. Two air supply nozzles 35 a and 35 b that communicate with each other and eject compressed air on the surface of the main shaft 3 are provided. An air supply passage 34c communicating with the air supply passage 42 of the spacer 40 is provided in the thrust bearing portion 30B portion of the bearing body 31. The thrust bearing sleeve 33 communicates with the air supply passage 34c. An air supply nozzle 35c for ejecting compressed air is provided on the surface of the thrust disk 3a. The air supply passage 34 and the air supply nozzle 35 are provided at a plurality of locations in the circumferential direction. In the example shown in FIG. 1, the air supply passage 34 and the air supply nozzle 35 are provided at two locations in the axial direction in the radial bearing portion 30 </ b> A, but may be one location or three or more locations. Further, although the air supply nozzle 35c is provided at one place in the radial direction in the thrust bearing portion 30B, it may be two or more places.

  As shown in FIG. 2, through holes 39 for the fixing bolts 50 are provided at a plurality of locations in the circumferential direction of the bearing main body 31 (positions corresponding to the through holes 29 and 41). The load-side radial thrust bearing 30 is fixed to the housing 2 at the load-side position of the spacer 40 by restraining the load side with the head of the fixing bolt 50 penetrating the through hole 39. In this arrangement, the thrust bearing portion 20B and the thrust bearing portion 30B are opposed to each other with the thrust disk 3a interposed therebetween.

<Exhaust bypass configuration>
Next, the configuration of the exhaust bypass route will be described. The load-side radial thrust bearing 30 and the front plate 9 have an exhaust bypass circuit 60 that communicates between them. In FIG. 2, an intake port 61 is provided in the radial bearing sleeve 32 on the opposite side of the air supply nozzle 35a, that is, at a position between the thrust disk 3a and the radial bearing portion 30A. The bearing main body 31 is provided with a main body exhaust passage 62 that communicates with the intake port 61, and the front plate 9 is provided with a plate exhaust passage 63 that communicates with the main body exhaust passage 62. Further the communication hole 9a of the front plate 9, communicates with the plate exhaust path 63, an exhaust port 64 for injecting exhaust air toward the surface of the main shaft 3 is provided. The intake port 61, the main body exhaust path 62, the plate exhaust path 63, and the exhaust port 64 are integrally communicated to form an exhaust bypass circuit 60. The exhaust port 64 of the front plate 9 functions as a radial bearing that ejects exhaust air at a position closer to the load side than any of the radial bearings 10, 20A, 30A and supports the main shaft 3 in the radial direction. The exhaust bypass circuit 60 is provided at a plurality of locations in the circumferential direction that do not overlap the supply passages 34 a and 34 b and the through holes 39.

<Thrust disk configuration, etc.>
Next, the configuration of the thrust disk 3a included in the main shaft 3 will be described. The thrust disk 3 a is a substantially disk-shaped part having the largest diameter than the other part of the main shaft 3, and is formed integrally with the main shaft 3. The thrust disk 3a includes a radial exhaust passage 3b that opens from the outer peripheral side surface and extends to the inner peripheral side at a plurality of locations in the circumferential direction, and a thrust direction exhaust passage 3c that opens between both end surfaces in the thrust direction. Each has communication inside the thrust disk 3a. In addition, each thrust direction exhaust passage 3c is arrange | positioned in the radial direction position substantially the same as the outer peripheral side surface of the main axis | shaft 3 in the periphery of the thrust disc 3a, and can distribute | circulate air between axial direction both sides.

<Other components>
The main shaft 3 includes a small-diameter portion 3d having a smaller diameter than other portions on the load side, and further includes a tool mounting portion 3e having the smallest diameter at the end on the load side. A front plate 9 is provided on the load side of the load side radial thrust bearing 30 . Through holes 91 for fixing bolts 51 are provided at a plurality of locations in the circumferential direction of the front plate 9 (positions that do not overlap with the air supply passages 34a and 34b, the through holes 39, and the exhaust bypass). The front plate 9 is fixed to the load side of the load-side radial / thrust bearing 30 by suppressing the load side with the head of the fixing bolt 51 passing through the through hole 91. In FIG. 2, for the convenience of illustration, a fixing bolt 51 for the front plate is shown overlapping with the fixing bolt 50 for fixing the load side radial thrust bearing 30 and the like. Further, the front plate 9 has the communication hole 9a through which the main shaft 3 passes, as described above, and the inner diameter of the communication hole 9a is smaller than the outer diameter of most of the main shaft 3 and is slightly smaller than the small diameter portion 3d of the main shaft. large. As a result, the front plate 9 can discharge the air ejected from the air supply nozzles 35a, 35b, etc. via the communication hole 9a and the radial bearing gap between the main shaft small-diameter portions 3d, and the main shaft 3 can be released to the load side. Can be prevented.

  As described above, the shaft hole 2A of the housing 2 has a shaft hole small diameter portion 2a having a small inner diameter in the non-load side portion in the load side range from the motor 4, and a shaft hole large diameter having a large inner diameter in the load side portion. It is part 2b. The radial bearing 10 is fitted to the inner peripheral side of the shaft hole small diameter portion 2a, and the radial bearing portion 20A of the anti-load side radial thrust bearing 20 is provided on the inner peripheral side of the shaft hole small diameter portion 2a, and the thrust bearing portion 20B is provided. The shaft hole large-diameter portion 2b is fitted to the inner peripheral side, the spacer 40 is fitted to the inner peripheral side of the shaft hole large-diameter portion 2b, and the load-side radial / thrust bearing 30 is entirely composed of the shaft hole large-diameter portion 2b. It is fitted on the inner periphery side. That is, all the bearings 10, 20, 30 and the spacer 40 are fitted to the inner peripheral side in the shaft hole 2A of the housing 2, and the axial load is applied through the opening 2B on the most load side of the shaft hole 2A. Can be inserted and removed on the side (see also FIG. 4 below).

<Configuration example of machining tool>
The spindle motor 1 of this embodiment mounts a rotary processing tool on the tool mounting portion 3e of the main shaft 3 and rotates the spindle. In the example shown in FIGS. 1 and 2, a grinding blade 100 is mounted as a processing tool. This grinding blade 100 includes a disk-shaped blade 101 having a cutting edge at an outer peripheral edge portion in an axial direction between two flanges 102 and 103, and a plurality of bolts 104 arranged at equal intervals in the circumferential direction. It is fixed integrally. The grinding blade 100 is rotationally driven in a state where it is coaxially mounted on the tool mounting portion 3e located on the most load side of the main shaft 3, and a groove or the like is formed on the surface of the workpiece by the cutting edge of the outer peripheral edge of the blade 101. Form and process (not shown). As a result, a radial load F is applied to the load side end portion of the main shaft 3 through the grinding blade 100 during the machining operation. In this example, the grinding blade 100 has been described as an example of a processing tool to be mounted on the main shaft 3, but a cutting cutter or the like may also be mounted. In this case as well, a radial load F is applied to the load side end of the main shaft 3 during the machining operation.

<Operation of spindle motor>
Next, the operation of the spindle motor 1 will be described. In the spindle motor 1, when compressed air is supplied to the air supply passage 7, the compressed air passes through the air supply nozzles 14a and 14b and flows into the bearing gap between the radial bearing 10 and the main shaft 3 to form a gas film. The compressed air passes through the air supply nozzles 25a and 25b and flows into the bearing gap between the radial bearing portion 20A of the anti-load side radial thrust bearing 20 and the main shaft 3 to form a gas film, and the air supply nozzle 25c passes through the bearing gap between the thrust bearing portion 20B and the thrust disk 3a to form a gas film. The compressed air passes through the air supply nozzles 35a and 35b and flows into the bearing gap between the radial bearing 30A of the load side radial thrust bearing 30 and the main shaft 3 to form a gas film, and the air supply nozzle 35c. And flows into the bearing gap between the thrust bearing portion 30B and the thrust disk 3a to form a gas film. Thereby, the main shaft 3 is supported in a non-contact manner in both the radial direction and the thrust direction. Thus, the main shaft 3 is driven by the motor 4 while being supported in a non-contact manner by the bearings 10, 20, 30.

  On the other hand, the exhaust path of the compressed air supplied to the bearings 10, 20, and 30 is as follows. As shown in FIG. 1, the air supplied to the radial bearing 30A of the load side radial thrust bearing 30 is directly exhausted to the outside from the bearing gap between the communication hole 9a of the front plate 9 and the small diameter portion 3d of the main shaft, or Exhaust air is exhausted from the bearing gap between the communication hole 9a and the main shaft small diameter portion 3d via the exhaust bypass circuit 60. A part of the air supplied to the thrust bearing 30B that circulates to the outer peripheral side of the thrust disk 3a passes through the radial exhaust path 3b and the thrust direction exhaust path 3c in the thrust disk 3a to the exhaust bypass 60. It flows in and is exhausted to the outside. Further, a part of the air supplied to the thrust bearing portion 20B of the anti-load side radial thrust bearing 20 passes to the exhaust bypass circuit 90 via the radial exhaust passage 3b and the thrust exhaust passage 3c in the thrust disk 3a. Or flows into the exhaust path 73 via the exhaust path 74 and the exhaust path 8, and both are exhausted to the outside. Further, the air supplied to the radial bearing 10 directly flows into the exhaust path 73 or flows into the exhaust path 73 via the exhaust path 74 and the exhaust path 8, and both are exhausted to the outside. About the air which flowed into the exhaust path 73, when passing through the magnetic space | gap 75 between the rotor 4a of the motor 4 and the stator 4b, the heat which generate | occur | produced in the stator 4b is cooled by the heat transfer accompanying forced convection. The heat is radiated to the outside of the housing 2 through the discharge hole 6a.

  In addition, the heat dissipation path | route of the heat | fever which generate | occur | produced in the stator 4b has the following two paths other than the path | route taken by the air which passes the above-mentioned magnetic space | gap 75. One is a path through which heat generated in the stator 4b is conducted to the housing 2 via the sleeve 5 and radiated from the outer peripheral surface of the housing 2 to the air. The other is a path through which heat generated in the stator 4 b is transmitted to the main shaft 3 through the magnetic gap 75 and radiated through the main shaft 3. The heat transferred to the main shaft 3 spreads over the entire main shaft 3 and is radiated directly from the load side shaft end surface of the main shaft 3 into the air, or is ejected from the bearings 10, 20, and 30 onto the surfaces of the main shaft 3 and the thrust disk 3a. Heat is transmitted to the compressed air, or is transmitted to the bearings 10, 20, and 30 through the bearing gap, and is radiated to the air directly or through the housing 2 or the like.

<Features of this embodiment>
As described above, the spindle motor 1 of the present embodiment has the bearings 10, 20, and 30 that support the main shaft 3 in the housing 2 in a non-contact manner so as to rotate the main shaft 3 and the processing tool 100 at a high speed and suppress noise and vibration. Is used. For the radial direction of the main shaft 3, radial bearings 20A and 30A configured to support the outer peripheral side surface of the main shaft 3 in a non-contact manner are used. For the thrust direction of the main shaft 3, radial bearings 20B and 30B configured to support the axial end surfaces of the thrust disk 3a of the main shaft 3 in a non-contact manner are used.

  In the spindle motor 1 provided with such non-contact type bearings 10, 20, 30, the positioning accuracy of the shaft center of the main shaft 3 is prevented so that the outer peripheral side surface of the main shaft 3 does not interfere with the inner peripheral side surface of each bearing 10, 20, 30. (Centering accuracy) is strictly required. However, as the spindle rotation speed increases, the mass of the spindle 3 can be easily adjusted to the center of the spindle 3 due to a slight deviation in the circumferential mass balance in the assembly and attachment of the machining tool 100 itself or in the radial direction during machining. Shaking and vibrations occur, and the main shaft 3 and the inner peripheral side surfaces of the bearings 10, 20, 30 interfere with each other, and seizure called “galling” is likely to occur.

  For example, in the comparative example of the spindle motor 1 ′ shown in FIG. 3 corresponding to FIG. 1, all the radial bearings 10 and 20A are arranged on the opposite side of the thrust disk 3a of the main shaft 3 (thrust disk 3a No radial bearing is provided on the load side. In such a spindle motor 1 ', the radial distance L' to the machining tool 100 becomes long across the thrust disk 3a even in the radial bearing 20A located on the most load side. For this reason, the support rigidity in the radial direction of the main shaft 3 on the load side is low, and the main shaft 3 is liable to be shaken or vibrated. The outer peripheral side surface of the main shaft 3 and the shaft hole 2A of the housing 2 or the radial bearings 10 and 20A Interference is likely to occur with the inner peripheral side of the.

  On the other hand, in the present embodiment, the radial bearing and the thrust bearing are provided on both the load side and the non-load side of the thrust disk 3a of the main shaft 3, that is, the radial bearing 30A is also arranged on the load side of the thrust disk 3a. doing. Thereby, the support rigidity to the main shaft 3 on the load side can be improved, and shaft shake and vibration of the main shaft 3 can be suppressed. Also in the main shaft 3 itself, the axial distance L from the position of the machining tool 100 serving as the power point to the position of the radial bearing 30A closest to the load serving as the fulcrum can be shortened, that is, the length of the cantilever portion of the main shaft 3 Therefore, the bending moment applied to the main shaft 3 can be suppressed, and interference between the outer peripheral side surface of the main shaft 3 and the inner peripheral side surfaces of the shaft hole 2A and the radial bearings 10, 20A, 30A can be avoided.

  Further, the spindle motor 1 is often used by assembling the housing 2 with high positioning accuracy to a production machine (not shown). For this reason, it is desired that the spindle motor 1 can be disassembled and maintained without removing the housing 2 from the production machine. However, in the configuration in which the radial bearing 30A and the thrust bearing 30B are provided on the load side from the thrust disk 3a as described above, the operation of extracting the main shaft 3 from the load side of the housing 2 tends to be complicated.

  On the other hand, in the present embodiment, the load side opening 2B of the shaft hole 2A in the housing 2 has a load side radial thrust bearing 30 disposed on the load side with respect to the thrust disk 3a and the main shaft 3 including the thrust disk 3a. The main shaft 3 can be easily pulled out from the load side of the housing 2 by being configured by the large-diameter portion 2b having a diameter that can be inserted and removed in the axial direction.

<Bearing replacement procedure>
Next, the bearing replacement procedure will be described with reference to FIG. In the spindle motor 1 that supports the spindle 3 in a non-contact state, the spindle 3 and the bearings 10, 20, and 30 come into contact with each other when the suspension control of the spindle 3 becomes impossible due to a power failure or whenever the apparatus is stopped. The bearings 10, 20, and 30 may be damaged. In particular, the load-side radial thrust bearing 30 and the anti-load-side radial thrust bearing 20 are more likely to come into contact with each other than the radial bearing 10 in the vicinity of the motor 4, so that the replacement frequency is generally increased. A procedure for replacing the load-side radial thrust bearing 30 and the anti-load-side load-side radial thrust bearing 20 correspondingly will be described below.

  In FIG. 4, for convenience of illustration, the spindle motor 1 is shown with the load side facing upward. First, as shown in FIG. 4A, all the fixing bolts 50 and 51 are loosened and removed from the housing 2 together with the front plate 9. Next, as shown in FIG. 4B, the load side radial thrust bearing 30 and the spacer 40 are extracted from the opening 2 </ b> B of the housing 2 to the load side in this order. Next, as shown in FIG. 4C, the main shaft 3 is pulled out from the opening 2B of the housing 2 to the load side and removed. Thereafter, as shown in FIG. 4D, the anti-load side radial thrust bearing 20 is extracted from the opening 2B of the housing 2 to the load side. The radial bearing portion 30A of the anti-load-side radial / thrust bearing 20 is fitted to the inner peripheral side of the small-diameter portion 2a of the shaft hole. For example, screw holes (not shown) are provided at a plurality of locations in the circumferential direction of the thrust bearing portion 20B. The thrust bearing portion 20B is tightened by screwing a screw (not shown) separately prepared as a jig into contact with the load side end surface 2c of the shaft hole small diameter portion 2a in the housing 2 in advance. The entire load-side radial thrust bearing 20 can be pulled out of the housing 2 while being separated from the load-side end surface 2c.

  For the load-side radial thrust bearing 30 and the anti-load-side radial thrust bearing 20 thus removed, the thrust bearing sleeves 23 and 33 and the radial bearing sleeves 22 and 32 are replaced as necessary. After replacement of the sleeve, the anti-load side radial thrust bearing 20, the main shaft 3, the spacer 40, and the load side radial thrust bearing 30 are attached to the housing 2 and the fixing bolt 50 is fastened by the procedure reverse to that described above. The front plate 9 is attached and the fixing bolt 51 is fastened. This completes the replacement of the bearing.

<Effect of embodiment>
According to the embodiment described above, the radial bearing and the thrust bearing are provided on both the load side and the anti-load side of the thrust disk 3a of the main shaft 3, that is, the radial bearing 30A is arranged also on the load side of the thrust disk 3a. doing. Thereby, the support rigidity to the main shaft 3 on the load side can be improved, and shaft shake and vibration of the main shaft 3 can be suppressed. Also in the main shaft 3 itself, the bending moment applied to the main shaft 3 can be suppressed, and interference between the outer peripheral side surface of the main shaft 3 and the inner peripheral side surfaces of the shaft hole 2A of the housing 2 and the bearings 10, 20, and 30 can be avoided. In the present embodiment, the opening 2B on the load side of the shaft hole 2A is formed so that the radial bearing 30A and the thrust bearing 30B disposed on the load side from the thrust disk 3a and the entire main shaft 3 including the thrust disk 3a are pivoted. The main shaft 3 can be easily extracted from the load side of the housing 2 by the shaft hole large diameter portion 2b that can be inserted and removed in the direction. As a result, the interference between the main shaft 3 and the housing 2 can be suppressed, and the disassembly work for maintenance can be easily performed.

  In the present embodiment, in particular, the radial bearings 10, 20A, 30A and the thrust bearings 20B, 30B are configured as fluid bearings for ejecting compressed air, which is a fluid, to support the main shaft 3 and the thrust disk 3a. The air supply passage 7 for supplying compressed air to the radial bearings 10, 20A, 30A and the thrust bearings 20B, 30B is provided. Thus, the radial bearings 10, 20A, 30A and the thrust bearings 20B, 30B can support the main shaft 3 in the radial direction and the thrust direction in a non-contact manner, and the fluid to be used is supplied to the air in the housing 2 By circulating through the passage 7, the cooling effect of the spindle motor 1 can also be obtained.

  In the present embodiment, in particular, the load side radial thrust bearing 30 and the front plate 9 exhaust air from between the thrust disk 3a and the radial bearing 30A disposed on the load side to the vicinity of the shaft hole opening 2A. An exhaust bypass route 60 is provided. Since air concentrates between the thrust bearing 30 </ b> B and the radial bearing 30 </ b> A in the load-side radial thrust bearing 30, it is necessary to exhaust air from there to the outside of the housing 2. The exhaust bypass circuit 60 arranged on the load side from the thrust disk 3a can shorten the overall length from the above-mentioned concentrated portion to the exhaust port 64 in the vicinity of the opening 2B of the shaft hole 2A, so that the diameter of the housing 2 is not increased. Air can be exhausted smoothly. The exhaust bypass circuit 60 is provided so as to pass through at least one of the housing 2, the radial bearing portion 30A, and the thrust bearing portion 30B, so that the total length to the exhaust port 64 in the vicinity of the shaft hole opening 2B is compared. Can be shortened.

  In the present embodiment, the exhaust port 64 of the exhaust bypass circuit 60 is a radial bearing that supports the main shaft 3 in the radial direction by injecting air at a position closer to the load than any of the radial bearings 10, 20A, 30A. Configured to work. As a result, it is possible to further improve the support rigidity to the main shaft 3 on the load side by reusing the air once used for the hydrodynamic bearing and further suppress the bending moment by shortening the cantilever portion of the main shaft 3. .

  In the present embodiment, in particular, the thrust disk 3a includes a radial exhaust passage 3b that opens from the outer peripheral side surface and extends toward the inner peripheral side, and a thrust direction exhaust passage 3c that opens between both end surfaces in the thrust direction. The thrust disk 3a communicates with the inside. Thereby, air can be smoothly circulated between the axial sides of the thrust disk 3a via the thrust exhaust passage 3c. Further, the fluid concentrated on the outer peripheral side of the thrust disk 3a can also flow to one axial direction side of the thrust disk 3a (the load side in the example of the present embodiment) via the radial direction exhaust path 3b and the thrust direction exhaust path 3c. In this way, it is possible to smoothly urge the air jetted around the thrust disk 3a to be exhausted toward one axial side of the thrust disk 3a. In particular, when the exhaust bypass circuit 60 having a high air exhaust function is provided as in the example of the present embodiment, the air around the thrust disk 3a is passed through the exhaust bypass circuit 60 without increasing the diameter of the housing 2. Can be exhausted smoothly.

  In the present embodiment, in particular, the radial bearing portion 30A and the thrust bearing portion 30B disposed on the load side from the thrust disk 3a are integrally formed as the load side radial thrust bearing 30, and this load side radial thrust bearing 30 is formed. Is fixed to the housing 2 by passing through the fixing shaft 50 in the axial direction of the main shaft 3. Thereby, the radial bearing part 30A and the thrust bearing part 30B arranged on the load side of the thrust disk 3a can be attached and detached at a time, and the maintainability of the spindle motor 1 can be improved. Further, since both the radial and thrust loads applied to the load side of the thrust disk 3a can be received by the fixing bolt 50, the load resistance in both directions is increased without increasing the diameter of the housing 2. The durability and reliability of the spindle motor 1 can be improved.

<Modification>
In addition, it is not restricted to the said embodiment, A various deformation | transformation is possible within the range which does not deviate from the meaning and technical idea.

  For example, in the above-described embodiment, the case where there are three radial bearings (radial bearing 10, radial bearing portion 20A, and radial bearing portion 30A) has been described as an example, but two radial bearings (for example, the radial bearing portion 20A is not provided). , Radial bearing 10 and radial bearing portion 30A only).

  In the above embodiment, the motor 4 is disposed on the anti-load side. However, for example, the motor 4 is disposed between the radial bearing 10 and the anti-load-side radial / thrust bearing 20 at the axial center position. An arrangement may be adopted.

  Moreover, although the case where each bearing was a fluid bearing was demonstrated as an example in the said embodiment, it is good also as a magnetic bearing which supports a main shaft by non-contact, for example with magnetic force.

  In addition to those already described above, the methods according to the above-described embodiments and modifications may be used in appropriate combination. In addition, although not illustrated one by one, the above-mentioned embodiment and each modification are implemented with various modifications within a range not departing from the gist thereof.

DESCRIPTION OF SYMBOLS 1 Spindle motor 2 Housing 2A Shaft hole 2B Opening part 3 Main shaft 3a Thrust disk 3b Radial direction exhaust path 3c Thrust direction exhaust path 4 Motor 4a Rotor 4b Stator 7 Air supply path (1st supply path)
DESCRIPTION OF SYMBOLS 9 Front plate 10 Radial bearing 20 Anti-load side radial thrust bearing 20A Radial bearing part 20B Thrust bearing part 30 Load side radial thrust bearing 30A Radial bearing part 30B Thrust bearing part 40 Spacer 50, 51 Fixing bolt 60 Exhaust bypass circuit 64 Exhaust Mouth 100 Grinding blade

Claims (5)

A housing having a shaft hole having an opening on the load side and communicating with the anti-load side;
A main shaft provided with a thrust disk and accommodated substantially coaxially in the shaft hole;
A radial bearing housed in the shaft hole and configured to support the main shaft in a radial direction in a non-contact manner;
A thrust bearing housed in the shaft hole and configured to perform non-contact support in the thrust direction of the thrust disk;
A motor having a rotor provided on the main shaft, and a stator provided on the inner peripheral side of the shaft hole so as to face the rotor;
A spindle motor that have a,
The radial bearing and the thrust bearing are respectively disposed on both the load side and the anti-load side of the thrust disk,
The opening is configured such that the radial bearing and the thrust bearing disposed on the load side from the thrust disk, and the main shaft including the thrust disk can be inserted and removed in an axial direction .
The radial bearing and the thrust bearing are configured as a fluid bearing that ejects fluid to support the main shaft and the thrust disk,
The spindle motor further includes a plate provided with a communication hole that is fixed to the load side of the housing and the radial bearing so as to cover the load side of the radial bearing disposed on the most load side and communicates with the shaft hole. And
At least one of the radial bearing and the thrust bearing disposed on the load side of the thrust disk and the plate are for exhausting the fluid from between the thrust disk and the radial bearing to the vicinity of the opening. Have an exhaust bypass,
A spindle motor characterized by that. Before Symbol housing has a first supply passage for supplying the fluid to the radial bearing to the thrust bearing,
The spindle motor according to claim 1. The exhaust port of the exhaust bypass route is configured as a radial bearing that ejects fluid at a position closer to the load side than any of the radial bearings and supports the main shaft in a radial direction.
3. A spindle motor according to claim 1, wherein The thrust disc has a radial exhaust passage that opens from the outer peripheral side surface and extends toward the inner peripheral side, and a thrust exhaust passage that opens between both end surfaces in the thrust direction, and communicates inside the thrust disc. ing,
The spindle motor according to any one of claims 1 to 3 , wherein the spindle motor is provided. The radial bearing and the thrust bearing arranged on the load side from the thrust disk are integrally formed,
The thrust bearings and integral the radial bearing is penetrating in the axial direction of the spindle by a fixing bolt fixed to the housing,
The spindle motor according to any one of claims 1 to 4 , wherein the spindle motor is provided.

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