JP4867682B2 - Rotating shaft sealing device - Google Patents

Description

  The present invention relates to a sealing device for a rotary shaft.

  Conventionally, as a rotary shaft sealing device, there is a sealing structure of a machine tool disclosed in Japanese Patent Laid-Open No. 9-253974 and a rotary shaft sealing device disclosed in Japanese Patent Laid-Open No. 2000-18395.

The sealing structure of a machine tool disclosed in Japanese Patent Laid-Open No. 9-253973 is to prevent the ingress of coolant from the outside by supplying pressurized air from an air supply source into the main body of the gear box. It is. Further, the rotary shaft sealing device disclosed in Japanese Patent Application Laid-Open No. 2000-18395 supplies coolant from the front of the front cap by supplying air from an air supply source to the gap between the main spindle and the front cap. And prevent entry of foreign objects.
Japanese Patent Laid-Open No. 9-253974 JP 2000-18395 A

  However, in the above-described sealing structure and sealing device, an air supply source must be provided outside. Therefore, the structure becomes complicated. In addition, there is a problem that the cost increases.

  The present invention has been made in view of such circumstances, and provides a rotary shaft sealing device that can seal a rotary shaft with a simple structure without the need for an external device such as an air supply source. The purpose is to do.

  In view of this, the present inventor has conducted intensive research to solve this problem, and as a result of repeated trial and error, an air supply source is provided outside by providing a fluid flow generator that generates a fluid flow by rotation of the rotating shaft. The inventors have come up with the idea that there is no need to separately provide a device such as the above, and have completed the present invention.

In other words, the rotary shaft sealing device of the present invention includes a housing, a rotary shaft that protrudes from the housing to the outside and is rotatably supported by the housing via the bearing, and one end of the rotary shaft and the bearing. A communication passage that is formed between the housing and the rotating shaft and communicates with the outside of the housing, and a fluid flow generating means that generates a flow of fluid toward one end of the rotating shaft by the rotation of the rotating shaft. I have. Then, the fluid flowing through the communication path toward one end portion of the rotating shaft prevents foreign matter from entering from the one end portion of the rotating shaft into the space between the housing and the rotating shaft. Thereby, it is not necessary to separately provide an external device such as an air supply source, and the rotating shaft can be sealed with a simple structure. As a result, costs can be reduced. The fluid flow generating means is constituted by a dynamic pressure groove that generates a fluid flow by generating a pressure difference by the rotation of the rotating shaft. Thereby, rotation of a rotating shaft can be utilized reliably.

Further, since the dynamic pressure groove is provided on either the inner peripheral surface of the housing or the outer peripheral surface of the rotating shaft, the rotation of the rotating shaft can be reliably used. The dynamic pressure grooves are inclined at a predetermined angle with respect to the axis of the rotation shaft and are formed at a predetermined interval. Thereby, the pressure difference by rotation of a rotating shaft can be generated reliably.

And it is located in the space between the housing and the rotating shaft, which is formed between one end portion of the rotating shaft and the bearing, and is disposed closer to the one end portion of the rotating shaft than the opening of the communication path. When the number is equal to or less than the predetermined number of rotations, the housing and the rotation shaft are contacted to close a gap between the housing and the rotation shaft, and when the rotation number of the rotation shaft exceeds the predetermined number of rotations, the housing or Sealing means is provided which is in a non-contact state with the rotating shaft and opens a gap between the housing and the rotating shaft. Thereby, the sealing effect by the flow of the fluid is low, and the sealing can be surely performed even when the rotating shaft is stopped or rotated at a low speed. Further, the sealing means includes a seal lip portion adjacent to the dynamic pressure groove and in contact with the rotating shaft, and the seal lip portion is subjected to a pressure difference due to an air flow generated by the dynamic pressure groove when a predetermined rotation speed is exceeded. In response, it becomes a non-contact state. Therefore, a non-contact state can be reliably achieved when the predetermined number of rotations is exceeded. Further, since the seal lip portion of the seal means is switched from the contact state to the non-contact state due to pressure change, the structure can be simplified as compared with the case where the actuator is provided. Therefore, cost can be suppressed.

Further, the dynamic pressure groove may be provided in a space between the housing and the rotating shaft, which is formed between one end of the rotating shaft and the bearing. The dynamic pressure groove is disposed between the bearing and one end portion side of the rotating shaft into which foreign matter enters. And the flow of the fluid which goes to the one end part side of a rotating shaft is generated with rotation of a rotating shaft. Therefore, it is possible to efficiently prevent foreign matter from entering the bearing from one end side.

Further, the rotating shaft is a work shaft to which one end projects into the machining area and the tool is fixed or a work shaft to which the work is fixed, and the communication path may have one end opened to the non-machining area. The rotation axis is a main axis to which a tool is fixed or a work axis to which a work as a workpiece is fixed. Therefore, a coolant for cooling the tool or workpiece is scattered in the machining area. Moreover, cutting powder and the like accompanying the processing are scattered. However, one end of the communication path is open to the non-processed area. Therefore, it is possible to prevent intrusion of foreign matters such as moisture and dust existing in the processing region from the communication path. In addition, you may provide the removal means which removes a foreign material in a communicating path.

  According to the rotary shaft sealing device of the present invention, it is not necessary to separately provide an external device such as an air supply source, and the rotary shaft can be sealed with a simple structure.

  Next, an embodiment is given and this invention is demonstrated in detail. In the present embodiment, an example in which the rotary shaft sealing device according to the present invention is applied to a rotary shaft sealing device of a machine tool will be described.

(First embodiment)
In 1st Embodiment, the example which applied the sealing device of the rotating shaft which concerns on this invention to the sealing device of the grindstone shaft of a grinding machine is shown.

  First, the structure of the grinding wheel shaft sealing device will be described with reference to FIGS. 1 and 2. Here, FIG. 1 is a sectional view of a seal device for a grindstone shaft of a grinding machine in the first embodiment. FIG. 2 is a partially enlarged view of the periphery of the dynamic pressure generator in FIG.

  As shown in FIG. 1, a grinding wheel shaft sealing device 1 includes a housing 10, a spindle 11 (rotary shaft), a pipe 12 (communication path), and a dynamic pressure generator 13 (fluid flow generating means, dynamic pressure generator). Means). The housing 10 includes a bearing housing 100 (housing), a grindstone shaft housing 101 (housing), and a front cap 102 (housing).

  The bearing housing 100 is a substantially cylindrical member for rotatably supporting the spindle 11 via a hydrostatic bearing 14 formed on the inner peripheral surface.

  The grindstone shaft housing 101 is a substantially cylindrical member for fixing the bearing housing 100 and the motor 15. A bearing housing 100 is fixed in front of the grindstone shaft housing 101. In addition, a stator 150 of the motor 15 is fixed to the rear via a stator housing 151.

  The front cap 102 is a substantially disk-shaped member for covering the front end surface of the bearing housing 100. The front cap 102 is fixed to the front end surface of the bearing housing 100.

  The spindle 11 is a substantially cylindrical member for transmitting the rotation of the motor 15 to the grindstone 16. The spindle 11 is rotatably supported by the bearing housing 100 via the hydrostatic bearing 14 with the front end protruding forward from the end face of the front cap 102. At this time, as shown in FIG. 2, a space 110 is formed between the front end of the spindle 11 and the hydrostatic bearing 14 by the inner peripheral surface of the front cap 102 and the outer peripheral surface of the spindle 11. As shown in FIG. 1, a substantially disc-shaped grindstone 16 is fixed to the front end portion of the spindle 11. A rotor 152 of the motor 15 is fixed to the rear end.

  The pipe 12 is a passage for communicating the space 110 formed in front of the hydrostatic bearing 14 to the rear outside of the grindstone shaft housing 101. The pipe line 12 is formed in the front cap 102, the bearing housing 100, and the grindstone shaft housing 101. The front end of the conduit 12 opens into the space 110. The rear end portion opens to the rear outside of the grindstone shaft housing 101.

  The dynamic pressure generating device 13 is a device for generating a pressure difference by the rotation of the spindle 11 to generate a forward fluid flow, specifically, an air flow. The dynamic pressure generator 13 includes a plurality of dynamic pressure grooves 130. The dynamic pressure groove 130 is formed on the outer peripheral surface of the spindle 11 facing the inner peripheral surface of the front cap 102. The dynamic pressure grooves 130 are inclined at a predetermined angle with respect to the axis of the spindle 11 and are formed at equal intervals in the circumferential direction at predetermined intervals.

  The grindstone shaft thus configured is fixed to a grinder main body (not shown). Further, a cover 17 that divides the processing region and the non-processing region is fixed to the front end surface of the grindstone shaft housing 101. For this reason, the rear end portion of the conduit 12 described above opens to a non-processed region.

  Next, the operation of the grinding wheel shaft sealing device will be described with reference to FIGS. When the spindle 11 rotates in FIG. 1, a pressure difference is generated in the space 110 by the dynamic pressure generator 13. Along with this, the air in the space 110 starts to flow forward. Air is continuously sucked from the rear end of the pipe line 12 opened to the non-working area. Then, as indicated by arrows in FIG. 2, the air is continuously discharged from the pipe 12 through the space 110 to the front of the front cap 102. The front end portion of the spindle 11 is disposed in the processing region and is exposed to splashed coolant and grinding powder. However, the inflow of these foreign substances can be prevented by the forward air flow by the dynamic pressure generator 13.

  Finally, the effect will be described. The grinding wheel shaft sealing device 1 includes a dynamic pressure generating device 13 that generates a forward air flow by the rotation of the spindle 11. Therefore, it is not necessary to separately provide an external device such as an air supply source as in the prior art, and the spindle 11 can be sealed with a simple structure. As a result, costs can be reduced.

  The dynamic pressure generator 13 is provided on the spindle 11. Therefore, the rotation of the spindle 11 can be used reliably. And it is arrange | positioned ahead of the bearing. Therefore, it is possible to efficiently prevent foreign matter from entering the hydrostatic bearing 14 from the front.

  Furthermore, the dynamic pressure generating device 13 is configured by a plurality of dynamic pressure grooves 130 formed on the outer peripheral surface of the spindle 11. Therefore, a pressure difference is produced between the front and rear by the rotation of the spindle 11. Thereby, the flow of air can be generated reliably. Moreover, the entry of foreign matter can be more reliably prevented by creating a pressure difference.

  In addition, the rear end portion of the pipe line 12 opens to a non-processed area. Therefore, entry of foreign matter such as cooling water and grinding powder scattered in the processing region from the pipe 12 can be prevented.

(Second Embodiment)
In 2nd Embodiment, the example which applied the sealing device to the main axis | shaft of the machining center to the rotating shaft which concerns on this invention is shown.

  First, the structure of the main shaft sealing device will be described with reference to FIGS. Here, FIG. 3 is a sectional view of the sealing device for the spindle of the machining center in the second embodiment. 4 is a partially enlarged view of the periphery of the dynamic pressure generating device in FIG. FIG. 5 is a partially enlarged view around the seal member in FIG. 4.

  As shown in FIG. 3, the main shaft sealing device 2 includes a housing 20, a spindle 21 (rotating shaft), a pipe 22 (communication path), and a dynamic pressure generator 23 (fluid flow generating means, dynamic pressure generating means). ) And a sealing member 24 (sealing means). The housing 20 includes an outer ring case 200, a bearing case 201, a main shaft housing 202, and a front cap 203.

  The outer ring case 200 is a substantially cylindrical member for rotatably supporting the spindle 21 via bearings 250 and 251. Bearings 250 and 251 are fixed in the outer ring case 200 at a predetermined interval in the axial direction.

  The bearing case 201 is a substantially cylindrical member for fixing the outer ring case 200 while rotatably supporting the spindle 21 via the bearings 252 and 253. Bearings 252 and 253 are fixed in front of the bearing case 201 at a predetermined interval. In addition, an outer ring case 200 is fixed to the rear.

The spindle housing 202 is a substantially cylindrical member for fixing the bearing case 201 and the motor 26. A rear end portion of the bearing case 201 is fixed in front of the main shaft housing 202. In addition, a stator 260 of the motor 26 is fixed to the rear via a stator housing 261.

  The front cap 203 is a substantially disk-shaped member for covering the opening in front of the bearing case 201. The front cap 203 is fixed to the front end of the bearing case 201.

  The spindle 21 is a substantially cylindrical member for transmitting the rotation of the motor 26 to the blade 271 via the holder 270. The spindle 21 is rotatably supported by the outer ring case 200 and the bearing case 201 via bearings 250 to 253 with the front end portion protruding forward from the end face of the front cap 203. At this time, as shown in FIG. 4, a space 210 is formed between the front end of the spindle 21 and the bearing 252 by the inner peripheral surface of the front cap 203 and the outer peripheral surface of the spindle 21. As shown in FIG. 3, a clamp unit 211 that clamps the holder 270 to which the cutting tool 271 is fixed is accommodated in the front of the spindle 21. Further, a push rod 212 for operating the clamp unit 211 is accommodated. Further, a rotor 263 of the motor 26 is fixed to the rear end portion of the spindle 21 via a rotor sleeve 262.

  The pipe line 22 is a passage for communicating a space 210 formed in front of the bearing 252 with the rear outside of the spindle housing 202. The pipe line 22 is formed in the front cap 203, the bearing case 201, and the main shaft housing 202. The front end of the pipe line 22 opens into the space 210. The rear end is open to the rear outside of the spindle housing 202.

  The dynamic pressure generating device 23 is a device for generating a pressure difference by the rotation of the spindle 21 to generate a forward fluid flow, specifically, an air flow. The dynamic pressure generator 23 includes a plurality of dynamic pressure grooves 230. The dynamic pressure groove 230 is formed on the outer peripheral surface of the large-diameter portion of the spindle 21 that faces the inner peripheral surface of the front cap 203. The dynamic pressure grooves 230 are inclined at a predetermined angle with respect to the axis of the spindle 21 and are formed at equal intervals in the circumferential direction at predetermined intervals.

  The sealing member 24 has elasticity for closing a gap between the front cap 203 and the spindle 21 formed in front of the bearing 252 when the spindle 21 is stopped or rotating at a low speed below a predetermined number of rotations. It is an annular member made of nitrile rubber or Teflon. The seal member 24 includes a main body portion 240 and a seal lip portion 241. The main body 240 is an annular portion. The seal lip 241 is a disk-shaped part formed on the inner peripheral surface of the main body 240 and is inclined toward one end of the main body 240. In addition, an annular recess 242 is provided at a connecting portion between the main body 240 and the seal lip 241. The main body 240 is fitted in an annular recess 2030 formed on the inner peripheral surface of the front cap 203 in front of the opening at the front end of the conduit 22 and behind the dynamic pressure generator 23. Has been. Further, the seal lip portion 241 is in close contact with the outer peripheral surface of the spindle 21 over the entire circumference in a state inclined forward. When the rotational speed of the spindle 21 exceeds a predetermined rotational speed and rotates at a high speed, the seal member 24 seals so that the seal lip 241 is deformed as the pressure difference increases and is not in contact with the spindle 21. The shape of the lip part 241 and the recessed part 242 is set. Here, the predetermined rotational speed is a rotational speed at which the flow of fluid generated by the dynamic pressure generating device 23, specifically, the flow of air can prevent entry of foreign matter from the front. Although depending on the performance of the dynamic pressure generating device 23, for example, when the shaft diameter of the spindle 21 is 100 mm, it is 1000 rpm.

  The main shaft thus configured is fixed to the machining center main body (not shown) via the main shaft case 204. Further, a cover 28 that partitions the machining area and the non-machining area is fixed to the front end surface of the spindle case 204. Therefore, the rear end portion of the pipe line 22 described above opens to a non-processed region.

  Next, the operation of the main shaft sealing device will be described with reference to FIGS. 3, 5 and 6. Here, FIG. 6 is a partially enlarged view around the seal member showing the state of the seal member when the spindle rotates at a high speed.

  In FIG. 3, when the spindle 21 rotates, a pressure difference is generated in the space 210 by the dynamic pressure generator 23. However, when the rotation speed of the spindle 21 is equal to or lower than the predetermined rotation speed, the seal lip portion 241 of the seal member 24 is not deformed as shown in FIG. Therefore, the gap between the front cap 203 and the spindle 21 is closed. The front end portion of the spindle 11 is disposed in the machining area and is exposed to the scattered coolant and cutting powder. However, the entry of these foreign substances can be prevented by the seal member 24.

  On the other hand, when the rotation speed of the spindle 21 exceeds the predetermined rotation speed, the seal lip portion 241 is deformed and brought into a non-contact state with respect to the spindle 21 as shown in FIG. . As a result, the gap between the front cap 203 and the spindle 21 is opened. Along with this, the air in the space 210 starts to flow. Air is continuously sucked from the rear end portion of the duct 22 opened to the non-working area. Then, as indicated by the arrows, the liquid is continuously discharged from the pipe line 22 through the space 210 to the front of the front cap 203. Therefore, the entry of foreign matter can be prevented by the forward air flow by the dynamic pressure generator 23.

  Finally, the effect will be described. The main shaft sealing device 2 includes a dynamic pressure generating device 23 that generates a forward air flow by the rotation of the spindle 21. In addition, a seal member 24 is provided that maintains a contact state with the spindle 21 when the rotation speed of the spindle 21 is equal to or less than a predetermined rotation speed, and enters a non-contact state when the rotation speed exceeds the predetermined rotation speed. Therefore, the spindle 21 can be sealed by the dynamic pressure generator 23 when the rotation speed exceeds the predetermined rotation speed by the seal member 24 when the rotation speed is equal to or lower than the predetermined rotation speed. Therefore, the sealing can be surely performed regardless of the rotational speed of the spindle 21. In addition, since the dynamic pressure generating device 23 is provided inside, it is not necessary to separately provide an external device such as an air supply source as in the prior art, and the spindle 21 can be sealed with a simple structure. As a result, costs can be reduced.

  Further, the seal member 24 is deformed by a pressure change, and is switched from a contact state to a non-contact state. Therefore, the structure can be simplified and the cost can be further suppressed.

(Third embodiment)
In the third embodiment, as in the second embodiment, an example in which the rotary shaft sealing device according to the present invention is provided to the spindle of a machining center is shown. The main shaft sealing device of the third embodiment is obtained by changing only the structure of the seal member with respect to the main shaft sealing device of the second embodiment.

  First, the structure of the main shaft sealing device will be described with reference to FIGS. Here, FIG. 7 is a partially enlarged view of the periphery of the seal member in the third embodiment. Here, only the structure of the seal member, which is different from the main shaft seal device of the second embodiment, will be described, and the description of the common parts other than the necessary parts will be omitted. In addition, the same code | symbol is attached | subjected and demonstrated to the element same as embodiment mentioned above.

  As shown in FIG. 7, the main shaft sealing device 2 ′ includes a sealing member 29. The seal member 29 is an annular shape for closing a gap between the front cap 203 and the spindle 21 formed in front of the bearing 252 when the spindle 21 is stopped or rotating at a low speed below a predetermined number of rotations. It is a member. The seal member 29 includes a main body portion 290 (actuator) and a seal lip portion 291. The main body 290 is an annular piezoelectric actuator that contracts in the axial direction when a voltage is applied thereto. The seal lip 241 is an annular material made of a material having elasticity that is in close contact with the axial end surface of the main body 290, specifically, nitrile rubber or Teflon. The main body 290 is in close contact with the rear side surface of the annular recess 2030. Further, the seal lip portion 291 is in close contact with the rear end surface of the large diameter portion of the spindle 21 over the entire circumference.

  Next, the operation of the main shaft sealing device will be described with reference to FIGS. Here, FIG. 8 is a partially enlarged view around the seal member showing the state of the seal member when the spindle rotates at a high speed.

  When the spindle 21 rotates, a pressure difference is generated in the space 210 by the dynamic pressure generator 23. However, when the rotation speed of the spindle 21 is equal to or lower than the predetermined rotation speed, no voltage is applied to the main body 290 of the seal member 29. Therefore, the main body 290 does not contract, and the seal member 29 maintains a contact state with the spindle 21 as shown in FIG. As a result, the gap between the front cap 203 and the spindle 21 is closed. Therefore, the sealing member 29 can prevent entry of foreign matters such as coolant and cutting powder.

  On the other hand, when the rotational speed of the spindle 21 exceeds a predetermined rotational speed, a voltage is applied to the main body 290 of the seal member 29. Therefore, the main body portion 290 contracts, and the seal member 29 is in a non-contact state with respect to the spindle 21 as shown in FIG. As a result, the gap between the front cap 203 and the spindle 21 is opened. Along with this, the air in the space 210 starts to flow. Air is continuously sucked from the rear end portion of the duct 22 opened to the non-working area. Then, as indicated by the arrows, the liquid is continuously discharged from the pipe line 22 through the space 210 to the front of the front cap 203. Therefore, the entry of foreign matter can be prevented by the forward air flow by the dynamic pressure generator 23.

  Finally, the effect will be described. The main shaft sealing device 2 ′ includes a dynamic pressure generating device 23 that generates a forward air flow by the rotation of the spindle 21. Further, a seal member 29 that contacts the spindle 21 when the rotation speed of the spindle 21 is equal to or less than a predetermined rotation speed and is in a non-contact state when the rotation speed exceeds the predetermined rotation speed is provided. Therefore, the spindle 21 can be sealed by the dynamic pressure generator 23 when the rotation speed exceeds the predetermined rotation speed by the seal member 29 when the rotation speed is lower than the predetermined rotation speed. Therefore, the sealing can be surely performed regardless of the rotational speed of the spindle 21. In addition, since the dynamic pressure generating device 23 is provided inside, it is not necessary to separately provide an external device such as an air supply source as in the prior art, and the spindle 21 can be sealed with a simple structure. As a result, costs can be reduced. Further, the seal member 29 includes a main body 290 made of a piezoelectric actuator that expands and contracts by voltage. Therefore, according to the rotation speed of the spindle 21, the seal member 29 can be reliably controlled to be in a contact state and a non-contact state.

  In the first to third embodiments, the dynamic pressure grooves 130 and 230 are formed on the outer peripheral surfaces of the spindles 11 and 21, but the present invention is not limited to this. It may be formed on the inner peripheral surface of the front caps 102 and 203, or may be formed on both. Further, instead of the groove, a blade-like unevenness may be formed, and the fluid flow may be generated by pushing the fluid through the unevenness. Even with such a configuration, a fluid flow can be generated as in the case of the dynamic pressure grooves 130 and 230.

  In the second and third embodiments, the example in which the seal members 24 and 29 are arranged behind the dynamic pressure generator 23 is described, but the present invention is not limited to this. It may be arranged in front of the dynamic pressure generator 23. What is necessary is just to be ahead rather than the opening of the front end part of the pipe line 22.

  Furthermore, in the first to third embodiments, the example in which the rotary shaft sealing device according to the present invention is applied to a grinding wheel shaft of a grinding machine or a main shaft sealing device of a machining center is given, but the present invention is not limited to this. Absent. You may apply to the sealing apparatus of the workpiece shaft to which a workpiece | work is fixed. If it is the same structure, it can apply not only to a machine tool but to other uses.

It is sectional drawing of the sealing apparatus of the grindstone axis | shaft of the grinding machine in 1st Embodiment. It is the elements on larger scale of the periphery of the dynamic pressure generator in FIG. It is sectional drawing of the sealing apparatus of the spindle of the machining center in 2nd Embodiment. FIG. 4 is a partially enlarged view around the dynamic pressure generating device in FIG. 3. It is the elements on larger scale of the seal member periphery in FIG. It is the elements on larger scale of the seal member periphery which shows the state of the seal member when a spindle rotates at high speed. It is the elements on larger scale around a seal member in a 3rd embodiment. It is the elements on larger scale of the seal member periphery which shows the state of the seal member when a spindle rotates at high speed.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Grinding wheel shaft sealing device (rotary shaft sealing device), 10 ... Housing, 100 ... Bearing housing, 101 ... Grinding wheel shaft housing, 102 ... Front cap, 11 ... Spindle (Rotary shaft), 110 ... space, 12 ... pipe (communication path), 13 ... dynamic pressure generating device (fluid flow generating means, dynamic pressure generating means), 130 ... dynamic pressure groove, DESCRIPTION OF SYMBOLS 14 ... Static pressure bearing, 15 ... Motor, 150 ... Stator, 151 ... Stator housing, 152 ... Rotor, 16 ... Grinding wheel, 17 ... Cover, 2 ... Main shaft 20 ... housing, 200 ... outer ring case, 201 ... bearing case, 202 ... spindle housing, 203 ... front cap, 2030 ... concave , 20 ... Spindle case, 21 ... Spindle (rotating shaft), 210 ... Space, 211 ... Clamp unit, 212 ... Push rod, 22 ... Pipe (communication path), 23 ...・ Dynamic pressure generating device (fluid flow generating means, dynamic pressure generating means), 24, 29... Sealing member (sealing means), 240... Main body part, 290. ... Seal lip part, 242 ... Recess, 250-253 ... Bearing, 26 ... Motor, 260 ... Stator, 261 ... Stator housing, 262 ... Rotor sleeve, 263 ... -Rotor, 270 ... Holder, 271 ... Cutting tool, 28 ... Cover

Claims (3)

A housing, one end projecting from the housing, a rotation shaft rotatably supported by the housing via a bearing, and formed between the one end of the rotation shaft and the bearing; A communication passage that communicates the space between the housing and the rotating shaft to the outside of the housing, and the housing and the housing are moved by the fluid flowing through the communicating passage toward the one end side of the rotating shaft. In the rotating shaft sealing device for preventing foreign matter from entering from the one end side of the rotating shaft into the space between the rotating shaft,
Fluid flow generating means for generating a fluid flow toward the one end of the rotating shaft by rotation of the rotating shaft ;
In the space between the housing and the rotary shaft, which is formed between the one end portion of the rotary shaft and the bearing, and closer to the one end portion of the rotary shaft than the opening of the communication path. When the rotational speed of the rotary shaft is less than or equal to a predetermined rotational speed, the clearance between the housing and the rotary shaft is closed in contact with the housing and the rotary shaft, and the rotational speed of the rotary shaft is When it exceeds the number of rotations, it is deformed by a pressure change, is in a non-contact state with the housing or the rotation shaft, and has a sealing means that opens a gap between the housing and the rotation shaft,
The fluid flow generating means is configured by a dynamic pressure groove that generates a fluid flow by generating a pressure difference by rotation of the rotation shaft, and the dynamic pressure groove is formed on an inner peripheral surface of the housing or the rotation shaft. Provided on any of the outer peripheral surfaces, inclined at a predetermined angle with respect to the axis of the rotary shaft, and formed at a predetermined interval;
The sealing means includes a seal lip portion adjacent to the dynamic pressure groove and in contact with the rotation shaft, and the seal lip portion generates an air flow generated by the dynamic pressure groove when the predetermined rotational speed is exceeded. A rotating shaft sealing device that is in a non-contact state in accordance with a pressure difference due to . The dynamic pressure grooves, wherein one end of the rotary shaft and is formed between the bearing to claim 1, wherein the provided in a space between the rotary shaft and the housing The rotary shaft sealing device described. The rotating shaft is a work shaft to which the one end projects into the machining area and a tool is fixed or a work shaft to which a work is fixed,
The communication passage, the sealing device for a rotary shaft according to claim 1 or 2, characterized in that one end is opened in the non-processing region.

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