JP6013112B2 - Cooling structure of bearing device - Google Patents

Description

  The present invention relates to a cooling structure for a bearing device, for example, a main shaft of a machine tool and a cooling structure for a bearing incorporated in the main shaft.

In a spindle device of a machine tool, it is necessary to suppress the temperature rise of the device to be small in order to ensure machining accuracy. However, recent machine tools have a tendency to increase the speed in order to improve the processing efficiency, and the heat generated from the bearing supporting the main shaft is also increasing as the speed increases. In addition, so-called motor built-in types in which a driving motor is incorporated in the apparatus are becoming more and more a cause of heat generation of the apparatus.
The rise in the temperature of the bearing due to heat generation results in an increase in preload, and we want to suppress it as much as possible in consideration of higher speed and higher accuracy of the spindle. For these reasons, in order to suppress the temperature rise of the spindle device, preload reduction during operation, cooling, and the like are taken. The main thing is as follows (patent documents 1-9).

A method for reducing the preload by reducing the amount of expansion in the radial direction of the inner ring by using ceramics having a lower density than steel and a high elastic modulus for the inner ring is disclosed (Patent Document 1). .
-Fins are formed on the outer peripheral surface of the inner ring side spacer arranged between the two bearings, and a passage for supplying a coolant is provided between the housing and the housing facing the fins. The cooling method is disclosed (Patent Documents 3 and 4).
・ The inner ring spacer is composed of two parts, an inner peripheral part and an outer peripheral part made of a porous material. A cooling medium passage is formed between the contact surfaces of the inner peripheral part and the outer peripheral part. A technique using a medium passage as a groove is disclosed (Patent Document 5).
A method is disclosed in which a groove is formed in at least one of the fitting surfaces of the inner cylinder of the bearing and the main shaft, and the main shaft is cooled by flowing a coolant into the groove (Patent Document 6).
A method is disclosed in which each bearing is lubricated with a lubricating liquid introduced into the central part of the main spindle of the main spindle device, and the main spindle is cooled from the inside by flowing the lubricating liquid in the axial direction along the inner peripheral surface of the main spindle. (Patent Document 7).
A method is disclosed in which cold air is injected into the space between two bearings at an angle in the rotational direction to produce a swirling flow (Patent Document 8).
・ An air outlet that cools the inner ring spacer is provided in the bearing box or main shaft, and a method of indirectly cooling the inner ring of the bearing by blowing compressed air to the inner ring spacer and cooling it is disclosed. (Patent Document 9).

JP 2012-26496 A JP-A 63-7251 JP-A-63-114846 JP-A-1-38340 Japanese Utility Model Publication No. 5-63747 JP-A-6-31585 Japanese Patent Laid-Open No. 7-24687 JP 2000-161375 A JP 2000-296439 A

  The bearing preload during operation is affected by the difference in radial expansion between the inner and outer rings. In general, when the steel inner and outer rings are used for operation, the heat generated in the inner ring is less likely to dissipate compared to the outer ring side where the bearing box is forcibly cooled with oil or the like. As a result, the temperature becomes inner ring> outer ring. Therefore, the amount of expansion on the inner ring side is larger than that on the outer ring side due to the combination of heat generation and centrifugal force. This is the main factor that increases the preload during operation.

The prior art is a technique for reducing the expansion of the inner ring during operation by changing the material of the inner ring and cooling the spacer. Patent Document 1 uses ceramics for the inner ring, and makes use of the characteristics of low density, low linear expansion, and high elastic modulus of the ceramics to reduce the preload by suppressing the amount of expansion of the inner ring during operation. However, even if ceramics are used for the inner ring, the expansion of the inner ring during operation is greatly affected by the expansion due to the temperature rise of the shaft, and the characteristics of the ceramics cannot be utilized, and the effect on reducing the bearing preload is small.
Patent Documents 2 to 7 are all techniques for lowering the inner ring temperature by cooling the spacer or the like with oil. Therefore, these techniques make the oil circulation path complicated and require ancillary equipment such as a pump for supply, resulting in an expensive spindle device. In Patent Documents 8 and 9, air is used as a cooling medium, and an apparatus can be constructed at a relatively low cost. However, cooling with air requires a large amount of air, and an apparatus capable of efficiently cooling with a small amount of air is desired.

  The object of the present invention is to reduce the temperature rise of the main shaft and bearing peripheral parts that affect the expansion of the inner ring, and use compressed air at an inexpensive, efficient and rationally fixed contact with the main shaft and the inner ring spacer. It is providing the cooling structure of the bearing apparatus which cools the inner ring | wheel used.

The cooling structure of the bearing device of the invention, the outer ring spacer and the inner ring spacer interposed respectively between the outer ring and the inner ring of a plurality of rolling bearings arranged in the axial direction, the outer ring and the outer ring spacer is disposed in the housing, the in bearing device inner ring and the inner ring spacer is fitted to the main shaft, the outer ring spacer, discharge port for discharging the compressed air of the cooling-only toward the outer circumferential surface of the inner ring spacer is inclined forward in the rotational direction and provided, on the outer circumferential surface of the inner ring spacer, the position for sprayed is discharged compressed air from the discharge opening, a plurality of holes arranged in a circumferential direction for receiving the compressed air blown inclined It is provided. Note that the inner ring spacer, so that the compression air discharged from the discharge port of the outer ring spacer is in direct contact with the surface of the main shaft, a plurality of radial holes with provided radially between said inner ring A circumferential groove may be provided on the inner peripheral surface of the seat to effectively cool the surface of the main shaft .

  According to this configuration, the bearing can be indirectly cooled by discharging the compressed air to the outer peripheral surface of the inner ring spacer from the discharge port provided in the outer ring spacer. The compressed air discharged from the outlet of the outer ring spacer cools the main shaft together with the inner ring spacer. Since the discharge port of the outer ring spacer is inclined forward in the rotational direction of the inner ring, the discharged compressed air strikes a part of the inner ring spacer in the circumferential direction. Thereby, the injection pressure of the compressed air discharged from the discharge port of the outer ring spacer can be applied to the inner ring spacer, and the effect of driving the main shaft can be expected.

  Here, the compressed air discharge port of the outer ring spacer is inclined forward in the rotation direction of the inner ring and the main shaft, for example, when the rotation direction is constant like the main shaft of a machine tool. This is based on the result of confirming through experiments that a good air flow can be expected in the clearance between the spacer and the inner ring spacer, and that the cooling effect is increased. The compressed air discharged from the outlet of the outer ring spacer contributes to the cooling of the inner ring spacer and the main shaft, and then passes through the bearing and is discharged to the outside of the bearing. At this time, the bearing is also cooled at the same time. Also become. Thus, the bearing can be cooled efficiently and rationally using the compressed air.

Therefore, the bearing device does not have a complicated structure, and expensive auxiliary equipment is not required, and the temperature of the bearing and the main shaft can be lowered with an inexpensive device. By reducing the bearing temperature during operation, an increase in bearing preload can be mitigated, and the bearing, that is, the bearing device can be further increased in speed, that is, the machining efficiency can be improved or the bearing life can be extended. Since the increase in the bearing preload is mitigated by the decrease in the operating spindle and bearing temperature, the initial preload can be increased, and the spindle rigidity at low speed can be increased and the machining accuracy can be improved. During operation, the temperature of the main spindle decreases, and deterioration in machining accuracy due to thermal expansion of the main spindle can be reduced.
There may be one or a plurality of outlets for compressed air in the outer ring spacer.

The inner ring may be made of ceramic.
The compressed air discharged from the outlet of the outer ring spacer cools the main shaft together with the inner ring spacer, thereby suppressing the radial expansion of the ceramic inner ring accompanying the temperature rise of the main shaft and making use of the ceramic material properties Can be expected. As a result, the preload can be reduced and the speed can be further increased.

The discharge port of the outer ring spacer is linear, and the discharge port is offset from an arbitrary radial line in a cross section perpendicular to the axis of the outer ring spacer in a direction perpendicular to the straight line. It is good as a thing. As the position of the discharge port of the outer ring spacer is offset as described above, the discharge port is directed in the tangential direction of the main shaft surface and in the rotational direction. As a result of the test, the larger the offset amount of the discharge port, the greater the decrease in the inner ring temperature.
The offset amount of the outlet of the outer ring spacer may be not less than 0.5 times the radius of the main shaft of the cooled part and not more than the inner diameter of the outer ring spacer. As a result of the test, the inner ring had a maximum temperature drop in the vicinity of the tangent to the surface of the main shaft from about 0.5 times the main shaft radius to the discharge port offset. It is thought that by offsetting the discharge port of the outer ring spacer and setting the air flow in the inner ring rotation direction, the cooling air flows stably in the rotation direction and effectively absorbs the heat of the surface of the inner ring spacer.

  In the outer peripheral surface of the inner ring spacer, a plurality of radial through holes arranged in the circumferential direction at positions where the compressed air discharged from the discharge port is sprayed are for causing the air to directly reach the main shaft, The main shaft can be cooled together with the inner ring spacer. Since the main shaft can be directly cooled with compressed air in this way, it has been confirmed by experiments that the temperature drop of the inner ring is larger than that in which the inner ring spacer does not have the same hole.

The hole may be a through hole or a non-through hole. In the case of the through hole, the cooling effect of directly cooling the main shaft can be further enhanced than that of the non-through hole.
Since a plurality of the holes are provided, a cooling effect for directly cooling the main shaft can be enhanced.
The inner ring spacer hole may be an inclined hole that inclines so as to incline at an angle opposite to the rotation direction as it goes outward in the radial direction.

A groove having a uniform cross section in the axial direction may be provided on the inner peripheral surface of the inner ring spacer. Since the outer peripheral surface of the main shaft is fitted to the inner peripheral surface of the inner ring spacer, by providing the groove on the inner peripheral surface of the inner ring spacer, the cooling air is distributed over the entire periphery of the main shaft surface. The area where the cooling air is in direct contact with the spindle surface can be increased. Moreover, the cooling effect which directly cools a main axis | shaft can be heightened more by making the hole connected to a groove | channel into the said inclined hole.
A groove having a V-shaped section, a recessed section, or a spiral shape may be provided on the surface of the main shaft facing the groove of the inner ring spacer. The cross section refers to a cross section obtained by cutting the main shaft along a plane including the main shaft axis. In this case, the heat radiation area can be further increased, and the cooling effect of directly cooling the main shaft can be further enhanced.
A cross section obtained by cutting the hole of the inner ring spacer along a plane perpendicular to the axis of the inner ring spacer may be rectangular or elliptical.

According to the cooling structure of the bearing device of the present invention, an outer ring spacer and an inner ring spacer are respectively interposed between outer rings and inner rings of a plurality of rolling bearings arranged in the axial direction, and the outer ring and the outer ring spacer are installed in a housing, In the bearing device in which the inner ring and the inner ring spacer are fitted to the main shaft, a discharge port that discharges compressed air toward the outer peripheral surface of the inner ring spacer is provided in the outer ring spacer so as to be inclined forward in the rotation direction. A plurality of holes arranged in a circumferential direction for receiving the compressed air blown at an inclination are provided at positions where the compressed air discharged from the discharge port is blown on the outer peripheral surface of the inner ring spacer, A groove may be provided on the outer peripheral surface of the inner ring spacer. In this case, the surface area of the outer peripheral surface can be made larger than that of the inner ring spacer having no groove, and heat can be efficiently radiated from the inner ring spacer surface. Therefore, the inner ring temperature is reduced and the bearing preload is reduced accordingly, so that the speed of the apparatus can be increased.
A cross section obtained by cutting the groove of the inner ring spacer along a plane including the axis of the inner ring spacer may be V-shaped or concave. The groove of the inner ring spacer may be a spiral groove. Thus, the surface area of the outer peripheral surface of the inner ring spacer can be increased.
An uneven portion may be provided on the outer peripheral surface of the inner ring spacer instead of the groove. Also in this case, the surface area of the outer peripheral surface can be made larger than that of the inner ring spacer, and the heat radiation from the inner ring spacer surface can be efficiently performed.

The outer ring spacer has an air oil supply port for supplying air oil into the rolling bearing, separately from the discharge port for discharging the compressed air, and the air oil supply port protrudes into the rolling bearing and protrudes into the inner ring. through the annular gap for air-oil passage between the outer peripheral surface may include a projecting portion facing. In this case, the air oil supplied from the air oil supply port adheres to the inner ring outer diameter surface. The oil adhering to the outer surface of the inner ring is introduced into the race surface of the inner ring using the surface tension and centrifugal force of the oil and used for lubricating the rolling bearing. The compressed air discharged from the discharge port is introduced into the rolling bearing through an annular clearance between the outer surface of the inner ring and the protruding portion, and is exhausted by absorbing heat in the rolling bearing. Thus, there is a cooling function in the rolling bearing as well as cooling in the inner ring spacer, so that more effective bearing cooling can be performed.

According to the cooling structure of the bearing device of the present invention, an outer ring spacer and an inner ring spacer are respectively interposed between outer rings and inner rings of a plurality of rolling bearings arranged in the axial direction, and the outer ring and the outer ring spacer are installed in a housing, In the bearing device in which the inner ring and the inner ring spacer are fitted to the main shaft,
A discharge port that discharges compressed air toward the outer peripheral surface of the inner ring spacer is provided in the outer ring spacer so as to be inclined forward in the rotation direction, and is discharged from the discharge port on the outer peripheral surface of the inner ring spacer. A plurality of holes arranged in the circumferential direction are provided at a position where the compressed air is sprayed, and the outer ring spacer has an air oil supply port for supplying air oil into the rolling bearing. And a protruding portion that protrudes into the rolling bearing and faces an outer peripheral surface of the inner ring via an air oil passage annular gap, and the air oil supply port is connected to the inner ring on the inner diameter side of the protruding portion. it may include nozzles for ejecting. In this case, the nozzle discharges air oil to the inner ring on the inner diameter side of the protrusion. Since air oil can be discharged closer to the inner ring after the protrusion is inserted into the bearing, the lubrication and cooling function of the bearing can be enhanced.
The air oil supply port and the compressed air discharge port may be combined. In this case, it is possible to reduce the amount of air for supplying air oil and to reduce the number of holes dedicated to air oil, and to simplify the device structure. Thereby, the manufacturing cost can be reduced.

  In the configuration in which the air oil supply port and the compressed air discharge port are combined, a radial through hole is provided in the inner ring spacer and is fitted to a main shaft on an inner peripheral surface of the inner ring spacer. An axial groove extending in the axial direction is provided in a part of the circumferential direction of the portion, and a part in the circumferential direction of both axial end surfaces of the inner ring spacer is communicated with the axial groove in the radial direction. An extending radial groove may be provided. In this case, the air oil discharged to the inner peripheral surface through the through-hole of the inner ring spacer passes through the axial groove and the radial groove in addition to the cooling of the main shaft and the inner ring spacer, thereby effectively cooling the inner ring. Can be done automatically. Further, when the air oil passes through the radial groove, the oil adheres to the end face of the inner ring and becomes an adhering flow, so that it can be reliably used as a lubricating oil for the bearing.

When the air oil supply port has a configuration including a protruding portion that protrudes into the rolling bearing and faces the outer diameter surface of the inner ring via an annular clearance, an inner diameter surface of the protruding portion, and an inner ring outer diameter surface The radial cross-sectional area of the circumferential clearance formed between the outer ring spacer and the outer ring spacer may be larger than the total cross-sectional area of the discharge port. The “radial cross-sectional area” of the circumferential clearance is defined as a section between the inner diameter surface of the protrusion and the outer diameter surface of the inner ring in a cross section obtained by cutting the bearing device along a plane perpendicular to the shaft center. It refers to the area of the circumferential clearance that is formed. The “total cross-sectional area” of the discharge ports refers to the sum total of the number of discharge ports of the area in a cross section obtained by cutting each discharge port along a plane perpendicular to the axial direction of the discharge port.
According to this configuration, the air discharged from the discharge port is reliably introduced into the rolling bearing through the annular clearance. This air is exhausted by absorbing heat in the rolling bearing.

In the configuration in which the air oil supply port and the compressed air discharge port are combined, or in the configuration in which the axial groove and the radial groove are provided in the inner ring spacer, the main purpose is lubrication in the rolling bearing. The nozzle for discharging air oil may be omitted. In this case, the device structure can be simplified, and thereby the manufacturing cost can be reduced.
The compressed air supply device that supplies the compressed air, that is, the cooling air, may be provided independently of the air oil supply device, or the empty circuit of the air oil supply device may be used without supplying oil.

  An air oil exhaust port for exhausting air oil may be provided, and the cooling air after cooling the inner ring spacer may be exhausted from the air oil exhaust port. Thus, by sharing the air oil exhaust path and the cooling air exhaust path, the structure of the apparatus can be simplified.

Two or more angular ball bearings arranged in a double row may be applied.
It may be applied to two or more tapered roller bearings arranged in a double row.
You may apply to a cylindrical roller bearing.
The inner rings of these angular ball bearings, tapered roller bearings, and cylindrical roller bearings may be made of ceramics.

  You may apply the cooling structure of the said bearing apparatus to a machine tool apparatus or a turbomachine apparatus.

The cooling structure of the bearing device of the invention, interposed outer ring spacer and the inner ring spacer, respectively between the outer ring and the inner ring of a plurality of rolling bearings arranged in the axial direction, the outer ring and the outer ring spacer is disposed in the housing, the In the bearing device in which the inner ring and the inner ring spacer are fitted to the main shaft,
The outer ring spacer, discharge port for discharging the compressed air of the cooling-only toward the outer circumferential surface of the inner ring spacer is provided to be inclined forward in the rotational direction, the outer peripheral surface of the inner ring spacer, the ejection Since compressed air discharged from the outlet is sprayed, a plurality of holes arranged in the circumferential direction to receive the compressed air blown at an angle are provided, so it is inexpensive and efficient using compressed air. The inner ring and the main shaft can be cooled well and reasonably.

It is sectional drawing of the cooling structure of the bearing apparatus which concerns on 1st Embodiment of this invention. It is the II-II sectional view taken on the line of FIG. FIG. 3 is a sectional view taken along line III-III in FIG. 2. It is a figure which shows the relationship between the offset amount of the discharge opening of compressed air, and the fall temperature of an inner ring | wheel in the same cooling structure. It is a figure which shows the comparison result of the inner ring fall temperature by the presence or absence of the hole of an inner ring spacer. It is a figure which shows the relationship between a rotational speed and bearing temperature. It is sectional drawing of the cooling structure of the bearing apparatus which concerns on other embodiment of this invention. It is sectional drawing of the cooling structure of the bearing apparatus which concerns on further another embodiment of this invention. It is sectional drawing of the cooling structure of the bearing apparatus which concerns on further another embodiment of this invention. It is sectional drawing of the cooling structure of the bearing apparatus which concerns on further another embodiment of this invention. It is sectional drawing of the cooling structure of the bearing apparatus which concerns on further another embodiment of this invention. It is sectional drawing of the cooling structure of the bearing apparatus which concerns on further another embodiment of this invention. It is the XIII-XIII sectional view taken on the line of FIG. It is the view which looked at the hole of the inner ring spacer of the bearing device from the outer diameter side. It is a figure which shows the relationship between a rotational speed and motor power consumption. It is a figure which shows the relationship between a rotational speed and bearing temperature. It is sectional drawing of a part of cooling structure of the bearing apparatus which concerns on further another embodiment of this invention. It is sectional drawing of a part of cooling structure of the bearing apparatus which concerns on further another embodiment of this invention. It is sectional drawing of a part of cooling structure of the bearing apparatus which concerns on further another embodiment of this invention. It is sectional drawing of a part of cooling structure of the bearing apparatus which concerns on further another embodiment of this invention. It is sectional drawing of the cooling structure of the bearing apparatus which concerns on further another embodiment of this invention. It is the XXII-XXII sectional view taken on the line of FIG. It is sectional drawing of the plane corresponding to the XXII-XXII line in FIG. 21 of the cooling structure of the bearing device which concerns on further another embodiment of this invention. It is sectional drawing of the cooling structure of the bearing apparatus which concerns on further another embodiment of this invention. It is sectional drawing of the cooling structure of the bearing apparatus which concerns on further another embodiment of this invention. FIG. 26 is a sectional view taken along line XXVI-XXVI in FIG. 25. It is the XXVII-XXVII sectional view taken on the line of FIG. It is sectional drawing of the cooling structure of the bearing apparatus which concerns on further another embodiment of this invention. It is the elements on larger scale of FIG. It is explanatory drawing which shows the positional relationship of the discharge port of an outer ring | wheel spacer, and the hole of an inner ring | wheel spacer. It is sectional drawing of the bearing apparatus provided with the cooling structure which concerns on further another embodiment of this invention. FIG. 32 is a partially enlarged view of FIG. 31. FIG. 32 is a sectional view taken along line XXXIII-XXXIII in FIG. 31. It is the figure which expanded and represented a part of outer ring spacer of the same bearing device. It is sectional drawing of the bearing apparatus provided with the cooling structure which concerns on further another embodiment of this invention. It is the figure which expanded and represented a part of outer ring spacer of the same bearing device. It is sectional drawing which shows the state which integrated the bearing apparatus shown in FIG. 35 and FIG. 36 in the main shaft apparatus of a machine tool.

A cooling structure for a bearing device according to a first embodiment of the present invention will be described with reference to FIGS.
The cooling structure of the bearing device in this example is applied to a machine tool device. However, it is not limited to machine tool devices. The following description also includes a description of the method for cooling the bearing.
As shown in FIG. 1, this bearing device has an outer ring spacer 4 and an inner ring spacer 5 interposed between outer rings 2 and 2 and between inner rings 3 and 3 of a plurality of rolling bearings 1 and 1 arranged in the axial direction. ing. The outer ring 2 and the outer ring spacer 4 are installed in the housing 6 with a clearance fit, and the inner ring 3 and the inner ring spacer 5 are fitted into the main shaft 7 with an interference fit. An angular ball bearing using a ceramic inner ring 3 is applied as each rolling bearing 1. These angular ball bearings are installed in a combination of the back surfaces, and counter bores are provided on the contact angle opposite sides of the inner ring outer diameter surface and the outer ring inner diameter surface, respectively. A plurality of rolling elements 8 are interposed between the raceway surfaces of the inner and outer rings 3, 2, and these rolling elements 8 are held by a cage 9 in a circumferentially equidistant manner. The cage 9 has an outer ring guide type ring shape. The bearing clearance is set by the difference in width between the inner ring spacer 5 and the outer ring spacer 4. The lubrication of these bearings 1 and 1 is air oil lubrication described later shown in FIG.

The cooling structure will be described.
As shown in FIG. 2, the outer ring spacer 4 is provided with a plurality (three in this example) of discharge ports 10 that discharge compressed air toward the outer peripheral surface of the inner ring spacer 5. The air discharge directions of these discharge ports 10 are inclined forward in the rotational direction L1 of the inner ring 3 (FIG. 1) and the main shaft 7, respectively. The plurality of discharge ports 10 are arranged at an equal circumference. Each discharge port 10 is linear and is offset from an arbitrary radial straight line L2 in a cross section perpendicular to the axis of the outer ring spacer 4 in a direction perpendicular to the straight line L2. In this example, the offset amount OS of the discharge port 10 of the outer ring spacer 4 is not less than 0.5 times the radius of the main shaft 7 of the cooled part and is not more than the inner diameter of the outer ring spacer 4.

  On the outer peripheral surface of the outer ring spacer 4, an introduction groove 11 for introducing compressed air, which is cooling air, is provided. The introduction groove 11 is provided in an intermediate portion in the axial direction on the outer peripheral surface of the outer ring spacer 4, and is formed in an arc shape communicating with each discharge port 10. In other words, the introduction groove 11 is provided on the outer peripheral surface of the outer ring spacer 4 over an angular range α1 that occupies most of the circumferential direction excluding a circumferential position where an air oil supply hole 12 described later is provided. The compressed air introduction path is configured as an independent path from the air oil for lubricating the bearing. Therefore, as shown in FIG. 1, the cooling air supply hole 13 is provided in the housing 6, and the introduction groove 11 communicates with the cooling air supply hole 13. A compressed air supply device 14 for supplying compressed air to the cooling air supply hole 13 is connected to the outside of the housing 6 by piping.

  As shown in FIG. 2, the inner ring spacer 5 is provided with a plurality of radial holes 15 (in this example, ten) in the circumferential direction. A cross section of each hole 15 viewed by cutting along a plane perpendicular to the axis of the inner ring spacer 5 is formed in a rectangular or elliptical shape. Each hole 15 is formed in a circular hole shape penetrating in the radial direction at a predetermined position in the circumferential direction in the inner ring spacer 5 and in an intermediate portion in the axial direction. Thereby, the main shaft 7 is directly cooled by causing the compressed air discharged from the discharge port 10 of the outer ring spacer 4 during operation to reach the outer surface of the main shaft 7 through the hole 15 of the inner ring spacer 5.

  As shown in FIG. 1, a radial clearance δ <b> 1 is provided between the outer peripheral surface of the inner ring spacer 5 and the inner peripheral surface of the outer ring spacer 4. At this time, the radial sectional area of the radial clearance formed between the outer peripheral surface of the inner ring spacer 5 and the inner peripheral surface of the outer ring spacer 4 is larger than the total sectional area of the discharge port 10 of the outer ring spacer 4. The radial clearance δ1 is set so as to increase. The “total cross-sectional area” of the discharge ports 10 refers to the total sum of the area of the discharge ports 10 in the cross section obtained by cutting each discharge port 10 along a plane perpendicular to the axial direction of the discharge ports 10. The “radial cross-sectional area” is a cross section of the bearing device taken along a plane perpendicular to the shaft center, and between the outer peripheral surface of the inner ring spacer 5 and the inner peripheral surface of the outer ring spacer 4. It means twice the area of the formed radial clearance. In the present embodiment, the radial air gap is formed between the outer peripheral surface of the inner ring spacer 5 and the inner peripheral surface of the outer ring spacer 4 in this embodiment. This is because it flows on both sides in the axial direction. Since the radial clearance δ1 is set as described above, the compressed air discharged from each discharge port 10 can flow smoothly and stably along the rotation direction while being in contact with the surface of the main shaft.

The lubrication structure will be described.
As shown in FIG. 3, the outer ring spacer 4 has an air oil supply port 16 for supplying air oil into the bearing. The air oil supply port 16 is provided for each of the rolling bearings 1 and 1. As shown in FIG. 2, the outer ring spacer 4 is provided with air oil supply holes 12, 12 communicating with the respective air oil supply ports 16. Each air oil supply hole 12 is formed at a predetermined depth radially inward from the outer peripheral surface of the outer ring spacer 4, and communicates with the air oil supply port 16 in the vicinity of the hole bottom. As shown in FIG. 3, each air oil supply port 16 is formed in a through hole shape having an inclination angle that inclines so as to reach the inner diameter side from the vicinity of the hole bottom toward the target bearing side. Each air oil supply port 16 in this example has an inclination angle so that the air oil discharged at a pressure determined from the air oil supply port 16 hits, for example, the vicinity of the boundary between the inner ring raceway surface and the rolling element 8.

  The housing 6 is provided with a bearing box supply hole 17 for air oil, and the air oil supply hole 12 communicates with the bearing box supply hole 17. An air oil supply device 18 that supplies air oil to the bearing box supply hole 17 is connected to the outside of the housing 6 by piping. During operation, the air oil supplied from the air oil supply device 18 is sequentially discharged to the bearing box supply hole 17 → the air oil supply hole 12 → the air oil supply port 16 → the inner ring raceway surface.

The exhaust structure will be described.
This bearing device is provided with an air oil exhaust port 19 for exhausting air oil. The air oil exhaust port 19 includes an exhaust groove 20 provided in a part of the outer ring spacer 4 in the circumferential direction, a bearing box exhaust groove 21 provided in the housing 6 and communicating with the exhaust groove 20, and a bearing box exhaust hole 22. Have The exhaust groove 20 of the outer ring spacer 4 is formed in a slit shape on the end face of the outer ring spacer 4 facing the outer ring end face on the bearing back side at a position in the circumferential direction diagonal to the position where the air oil supply hole 12 is provided. The The bearing box exhaust groove 21 of the housing 6 is formed over the same circumferential position as the exhaust groove 20 of the outer ring spacer 4 and communicates with a bearing box exhaust hole 22 extending in the axial direction.
When air and oil used for lubrication of the rolling bearing 1 pass through the bearing in the axial direction and are discharged to the outside, the exhaust groove 20 passes through the bearing box exhaust groove 21 and the bearing box exhaust hole 22. Are released to the outside.
In this example, the cooling air after cooling the inner ring spacer is exhausted from the air oil exhaust port 19. In other words, the air oil exhaust path and the cooling air exhaust path are shared.

FIG. 4 is a diagram showing the relationship between the offset amount of the cooling air discharge port 10 and the temperature drop of the inner ring 3 in this cooling structure. In the test, an angular contact ball bearing whose inner ring 3 has an inner diameter of φ70 mm is operated at 17000 min ⁻¹ with air-oil lubrication, and the temperature drop of the inner ring 3 without cooling (air supply pressure 0 kPa) and during cooling (air supply pressure 400 kPa). In relation to the offset amount of the discharge port 10. The offset direction of each discharge port 10 is determined such that the flow of air discharged from each discharge port 10 is the same as the rotation direction of the main shaft 7 and the inner ring 3.

  As a result of the test, as the offset amount OS of the discharge port 10 increases, the temperature drop of the inner ring 3 increases, and the maximum drop temperature is about 0.5 times the spindle radius and near the tangential position on the spindle surface. I understand. By offsetting the discharge port 10 of the outer ring spacer 4 and setting the air flow in the inner ring rotation direction, the cooling air flows stably in the rotation direction and effectively absorbs the heat of the surface of the inner ring spacer 5. This is probably because of this.

  FIG. 5 is a view showing a comparison result of the inner ring lowering temperature depending on the presence / absence of the hole 15 (FIG. 2) of the inner ring spacer 5. As shown in the figure, it can be seen that the temperature drop of the inner ring 3 is larger when the inner ring spacer 5 has the radial hole 15 than when the inner ring spacer 5 does not have the hole 15. This is considered because the cooling air discharged from the discharge port 10 of the outer ring spacer 4 reaches the outer surface of the main shaft 7 through the hole 15 and directly cools the main shaft 7.

FIG. 6 shows the result of an operation test in which the ceramic inner ring bearing 1 is actually incorporated as shown in FIG. The offset amount OS of each discharge port 10 in this operation test is 33.6 mm, respectively, compared with no cooling air (air supply pressure 0 kPa) and during cooling (air supply pressure 300 kPa). 3 and the temperature of the outer ring 2 were detected. As shown in FIG. 6, when the rotation speed was 19000 min ⁻¹ , a temperature drop of 10 ° C. or more was recognized by cooling. Further, if when the inner temperature reached 60 ° C. and a high speed limit, relative to the rotational speed 19000Min ^-1 when no cooling, so that the speed can be of up to 21000Min ^-1 by performing cooling. The lowering of the inner ring temperature due to cooling means that the bearing preload is reduced correspondingly, and it can be said that the speed can be increased.

  According to the cooling structure of the bearing device described above, the rolling bearing 1 is indirectly cooled by discharging compressed air to the outer peripheral surface of the inner ring spacer 5 from the discharge port 10 provided in the outer ring spacer 4. Can do. The compressed air discharged from the discharge port 10 of the outer ring spacer 4 cools the inner ring spacer 5, and the position of the discharge port 10 of the outer ring spacer 4 is offset as described above. The main shaft 7 is cooled in the direction tangential to the surface of the main shaft and in the rotational direction. As a result of the test, the decrease in the inner ring temperature increases as the offset amount OS of the discharge port 10 increases. By offsetting the discharge port 10 of the outer ring spacer 4 and setting the air flow in the inner ring rotation direction, the cooling air flows stably in the rotation direction and effectively absorbs the heat of the surface of the inner ring spacer 5 and the main shaft 7. can do.

  The reason that the compressed air discharge port 10 of the outer ring spacer 4 is inclined forward in the rotation direction of the inner ring 3 and the main shaft 7 is effective when the rotation direction is constant, for example, as in the main shaft of a machine tool. This is based on the result of experiments confirming that a good air flow can be expected in the clearance δ1 between the outer ring spacer 4 and the inner ring spacer 5 and that the cooling effect is increased. Further, the compressed air discharged from the outer ring spacer 4 contributes to cooling of the inner ring spacer 5 and the main shaft 7, and then passes through the bearing and is discharged to the outside of the bearing. At this time, the bearing is also cooled at the same time. It will also be a thing. Thus, the bearing can be cooled efficiently and rationally using the compressed air.

  Therefore, the temperature of the bearing 1 and the main shaft 7 can be reduced with an inexpensive device without requiring a complicated structure for the bearing device and without requiring expensive incidental equipment. By reducing the bearing temperature during operation, an increase in bearing preload can be mitigated, and the bearing, that is, the bearing device can be further increased in speed, that is, the machining efficiency can be improved or the bearing life can be extended. The initial preload can be increased by increasing the bearing preload due to the reduction of the inner ring radial expansion due to the decrease in the bearing temperature and the decrease in the spindle temperature during operation. Improvement in accuracy can be expected.

  Since the radial hole 15 is provided in the inner ring spacer 5, the discharged compressed air reaches the outer surface of the main shaft 7 through the hole 15 of the inner ring spacer 5, so that the main shaft 7 is cooled together with the inner ring spacer 5. can do. Since the main shaft 7 can be directly cooled with compressed air in this way, the temperature drop of the inner ring 3 can be made larger than that in which the inner ring spacer 5 does not have the same hole.

Since a plurality of holes 15 in the inner ring spacer 5 are provided along the circumferential direction, the cooling effect of directly cooling the main shaft 7 can be enhanced as compared with, for example, providing one hole 15 in the inner ring spacer 5. .
Further, since the air oil exhaust path and the cooling air exhaust path are shared, the structure of the apparatus can be simplified, and the manufacturing cost can be reduced.

Another embodiment of the present invention will be described.
In the following description, the same reference numerals are given to the portions corresponding to the matters described in the preceding forms in each embodiment, and the overlapping description is omitted. When only a part of the configuration is described, the other parts of the configuration are the same as those described in the preceding section. Not only the combination of the parts specifically described in each embodiment, but also the embodiments can be partially combined as long as the combination does not hinder.

  As shown in FIG. 7, a groove 5 a may be provided on the outer peripheral surface of the inner ring spacer 5. In this example, the groove 5a of the inner ring spacer 5 is formed to have a V-shaped cross section as viewed by cutting along a plane including the axis of the inner ring spacer 5. In addition, the groove 5a having a V-shaped cross section is formed as a plurality of circumferential grooves or spiral grooves arranged at predetermined intervals in the axial direction. The groove 5a can increase the surface area of the inner ring spacer 5 to efficiently dissipate heat from the surface of the spacer. The groove 5a may be, for example, a groove having a concave cross section other than the V-shaped groove having a cross section. The inner ring spacer 5 is preferably made of a material having a higher heat emissivity than that of a steel material such as bearing steel. In this case, the cooling effect can be further improved.

  As shown in FIG. 8, the hole 15 of the inner ring spacer 5 is inclined at an angle opposite to the rotational direction L1 of the inner ring 3 and the main shaft 7 (indicated by an angle β in FIG. 8) as going outward in the radial direction. It is good also as the inclined hole 15 which inclines like this. In this case, the compressed air discharged from the discharge port 10 of the outer ring spacer 4 can be effectively captured by the inclined hole 15. As a result, the amount of air to the surface of the main shaft 7 increases and the main shaft 7 is effectively cooled.

  As shown in FIG. 9, in the configuration in which the groove 5a is provided on the outer peripheral surface of the inner ring spacer 5, a circumferential groove 5b having a width larger than the diameter dimension of the hole is provided on the inner peripheral surface of the inner ring spacer 5. Also good. In this case, the compressed air discharged from the discharge port 10 of the outer ring spacer 4 flows in from the hole 15 and flows in the circumferential groove 5b. As a result, the cooling air reaches the entire circumference of the main shaft surface, and the area where the cooling air directly contacts the main shaft surface can be increased. Therefore, the cooling effect for directly cooling the main shaft 7 can be further enhanced.

  As shown in FIG. 10, the outer ring spacer 4A has an air oil supply port 16 for supplying air oil into the bearing. The air oil supply port 16 protrudes into the bearing and forms air oil between the inner ring outer diameter surface 3a. It is good also as what includes the protrusion part 23 which faces through the cyclic | annular clearance | gap (delta) 2 for passage. The outer ring spacer 4 </ b> A in this example includes an outer ring spacer body 24 and nozzles 25, 25 configured separately from the outer ring spacer body 24. The outer ring spacer main body 24 is formed in a substantially T-shaped cross section, and ring-shaped nozzles 25 and 25 are fitted on both sides of the outer ring spacer main body 24 to be fixed symmetrically. Each nozzle 25 is provided with a protrusion 23 that protrudes into the bearing.

In the outer ring spacer main body 24, both side surfaces 24a and 24a and inner peripheral surfaces 24b and 24b, which are contact surfaces with the nozzles 25, are each subjected to polishing. Polishing thefts are provided at the corners of the side surfaces 24a and the inner peripheral surface 24b. The inner surface and outer peripheral surface of each nozzle 25 are also polished. An annular seal member 26 for preventing air oil leakage from the air oil supply port 16 is provided on the contact surface of each nozzle 25 with the side surface 24a. An annular recess 3aa is provided at a position facing the air oil supply port 16 on the inner ring outer diameter surface 3a.
The annular clearance δ2 is set as follows similarly to the above-mentioned radial clearance δ1. The radial sectional area of the annular clearance δ2 formed between the inner ring outer diameter surface 3a and the inner peripheral surface of the protrusion 23 is larger than the total sectional area of the discharge port 10 of the outer ring spacer 4A. An annular clearance δ2 is set.

  According to the configuration shown in FIG. 10, the air oil discharged from the air oil supply port 16 is introduced into and adhered to the annular recess 3aa of the inner ring outer diameter surface 3a. The adhered oil is introduced into the inner ring raceway surface using the surface tension and centrifugal force of the oil and used for lubricating the bearing 1. Since the air oil can be discharged closer to the inner ring 3 after the protrusion 23 is inserted into the bearing, the lubrication and cooling function of the bearing 1 can be enhanced. The compressed air discharged from the cooling discharge port 10 is introduced into the bearing through the annular clearance δ2, and is exhausted by absorbing heat in the bearing. Thus, in addition to the cooling in the inner ring spacer 5, there is also a cooling function in the bearing, and more effective bearing cooling can be performed. By setting the annular clearance δ2 as described above, the compressed air discharged from the cooling discharge port 10 is formed by the inner ring outer diameter surface 3a and the nozzle 25 as indicated by an arrow A1 in FIG. It can be reliably introduced into the bearing through the annular clearance δ2. Therefore, the compressed air is exhausted by absorbing heat in the bearing.

  Further, in this configuration, the compressed air discharged from the discharge port 10 of the outer ring spacer 4A is surely passed through the inside of the bearing and exhausted, so that air oil supply for bearing lubrication is provided as in the previous embodiments. The opening 16 may not be provided separately from the discharge port 10 but air oil may be blown out from the discharge port 10. In other words, the air oil supply port 16 and the compressed air discharge port 10 may be combined. In this case, it is possible to reduce the amount of air for supplying air oil and to reduce the number of holes dedicated to air oil, and to simplify the device structure. Thereby, the manufacturing cost can be reduced.

The configuration shown in FIG. 11 may be used. That is, the dedicated air oil supply port 16 (FIG. 10) is omitted, and the air oil supply port 16 and the compressed air discharge port 10 are used in common. Further, an axial groove 27 extending in the axial direction is provided on a part of the inner peripheral surface of the inner ring spacer 5A in the circumferential direction of the portion fitted with the main shaft. In addition, radial grooves 28 and 28 that communicate with the axial groove 27 and extend in the radial direction are provided in a part of the circumferential direction of both axial end surfaces of the inner ring spacer 5A.
According to this configuration, the air oil discharged to the inner peripheral surface through the hole 15 of the inner ring spacer 5A is cooled along with the cooling of the main shaft 7 and the inner ring spacer 5A as shown in the arrow A2 in FIG. 27, the inner ring 3 can be effectively cooled by passing through the radial grooves 28 and 28 in sequence. Further, when the air oil passes through the radial groove 28, the oil adheres to the end face of the inner ring and becomes an adhering flow, so that it can be reliably used as the lubricating oil for the rolling bearing 1.

  12 to 14 show further different embodiments. This cooling structure is suitable for use in a bearing device composed of an angular ball bearing for a high-speed main shaft, in which the temperature rise of the inner ring becomes large and excessive preload becomes a problem. As shown in FIG. 12, the outer rings 2, 2 and the outer ring spacer 4 </ b> A of each rolling bearing 1, 1 are positioned in the axial direction by the step portion 6 a of the housing 6 and the end surface cover 40. The inner rings 3 and 3 and the inner ring spacer 5 of each rolling bearing 1 and 1 are positioned in the axial direction by positioning spacers 41 and 42 on both sides. The left positioning spacer 42 in the figure is fixed by a nut 43 screwed onto the outer periphery of the main shaft 7. As in the embodiment of FIG. 10, the outer ring spacer 4 </ b> A is composed of an outer ring spacer body 24 and a pair of nozzles 25, 25 for air oil, and the width of the outer ring spacer body 24 and the inner ring spacer 5. The initial preload of the rolling bearing 1 is set and used due to the dimensional difference.

  In this cooling structure of the bearing device, a bucket-shaped hole that is a non-through hole and is recessed with respect to the outer peripheral surface of the inner ring spacer 5 is provided as the hole 15 provided on the outer peripheral surface of the inner ring spacer 5. As shown in FIG. 13, the bucket-shaped hole 15 has an inclined shape in which the bottom depth becomes deeper toward the front in the axial rotation direction L <b> 1. The bucket-shaped hole 15 in the illustrated example has an arc shape at the front end in the axial rotation direction L1 when viewed from the outer diameter side as shown in FIG. 14, but may not be arc-shaped.

  When the hole 15 has the bucket shape, the compressed air discharged from the discharge port 10 of the outer ring spacer 4A can be effectively received by the hole 15, so that the driving force of the main shaft 7 can be further assisted. In order to confirm the effect of providing the bucket-shaped hole 15, a test was performed using a bearing device having the configuration shown in FIG. 12.

  The test is performed by replacing the driving force assisting of the main shaft 7 by compressed air with the power consumption of the driving motor, and the difference in motor power consumption between the case where there is no bucket-shaped hole 15 in the inner ring spacer 5 and the case where it exists. I saw. As the rolling bearing 1, an angular ball shaft having an inner diameter of 70 mm was used. The jet pressure of the compressed air was 400 KPa. The main shaft 7 is driven by a built-in motor (not shown) disposed on the left side of FIG. FIG. 15 shows the result when the power consumption values of the motor are arranged in relation to the rotational speed. FIG. 16 shows the temperature result of the rolling bearing 1 at that time.

From the test results, it can be seen that the power consumption of the motor is smaller when the bucket shape 15 is present than when it is absent. This can be said that the power consumption of the motor has been reduced by the increase in driving force due to the bucket-shaped hole 15. Incidentally, the motor power consumption at 20000 min ⁻¹ was reduced by about 100 W due to the presence of the bucket 15A. The bearing temperature is lower when the bucket-shaped hole 15 is present than when it is absent. This can be presumed to be because heat generation from the motor is reduced by reducing the power consumption of the motor, and heat transmitted from the motor unit to the rolling bearing 1 is reduced. In particular, it can be seen that the temperature of the inner ring 3 is greatly reduced as compared with the temperature of the outer ring 2, and the temperature rise of the motor rotor is suppressed.

  When compressed air is injected from the discharge port 10 of the outer ring spacer 4 </ b> A to the bucket-shaped hole 15 of the rotating inner ring spacer 4, an injection sound is generated in the space of the hole 15 and a plurality of holes 15. Wind noise is generated. In order to reduce these noises, the configuration shown in FIG. 17 or FIG. 18 is preferable.

  The cooling structure of the bearing device of FIG. 17 has a radial direction between the axially outer end portion on the inner peripheral surface of the nozzle 25 of the outer ring spacer 4A and the axially outer portion of the hole 15 on the outer peripheral surface of the inner ring spacer 5. The dimension of the clearance δa was reduced. In this example, the protrusion 25a protruding toward the inner diameter side is provided at the outer end in the axial direction of the nozzle 25 to reduce the dimension of the radial clearance δa. The dimension of the radial clearance δa may be reduced by providing a convex portion (not shown) that protrudes toward the radial side.

  In the cooling structure of the bearing device of FIG. 18, the central portion in the axial direction including the bucket-shaped hole 15 on the outer peripheral surface of the inner ring spacer 5 is formed as a convex portion 5 c protruding to the outer diameter side, and the inner peripheral surface of the nozzle 25 is formed. A stepped shape having a large inner diameter in the axial center is formed, and an axial clearance δb is formed by the side surfaces of the convex portion 5 c of the inner ring spacer 5 and the step surface of the nozzle 25.

  The clearance areas of the radial clearance δa and the axial clearance δb are about 10 times the total cross-sectional area of the compressed air discharge port 10 in consideration of cooling compressed air exhaust. The clearance area referred to here is the area of the clearance on one side of the radial and axial clearances δa and δb on both sides in the axial direction. The clearance area of the radial clearance δa is calculated by (the clearance dimension of the radial clearance δa) × (the circumferential length of the radial clearance δa), and the clearance area of the axial clearance δ is (the axial clearance δb (Clearance dimension) × (circumferential length of axial clearance δb). This is a numerical value derived from the result of the test, and the relationship between the total cross-sectional area of the discharge port 10 and the clearance area described above makes it possible to reduce the flow rate of the compressed air for cooling and to reduce the noise level reasonably. Can be achieved.

  As shown in FIGS. 19 and 20, when the outer ring spacer 4 has an air oil supply port 16 that directly discharges air oil to the raceway surface of the inner ring 3, the noise caused by the compressed air is also similar to the above. A configuration to reduce can be applied. That is, as shown in FIG. 19, the clearance dimension δa of the radial clearance between the inner peripheral surface of the nozzle 25 of the outer ring spacer 4 and the axially outer portion of the hole 15 on the outer peripheral surface of the inner ring spacer 5 is reduced. . Further, as shown in FIG. 20, the central portion in the axial direction including the bucket-shaped hole 15 on the outer peripheral surface of the inner ring spacer 5 is formed as a convex portion 5 c that protrudes to the outer diameter side, and the nozzle 25 is more than the outer ring spacer body 24. Is protruded toward the inner diameter side, and an axial clearance δb is formed by both side surfaces of the convex portion 5c of the inner ring spacer 5 and a side surface of the portion protruding toward the inner diameter side of the nozzle 25.

  21 and 22 show different cooling structures for the bearing device. As shown in FIG. 22, the hole 15 of the inner ring spacer 5 may be an inclined hole positioned on the rotation direction L1 side of the main shaft 7 as it goes from the outer peripheral surface of the inner ring spacer 5 to the inner peripheral surface. When the hole 15 is an inclined hole, the hole 15 can efficiently receive the injection pressure of the compressed air discharged from the discharge port 10, and the effect of assisting the driving force of the main shaft 7 is high. In this example, compressed air is supplied to each discharge port 10 of the outer ring spacer 4 through an individual cooling air supply hole 13.

  As shown in FIG. 23, even if the hole 15 of the inner ring spacer 5 is an inclined concave portion that is inclined in the rotational direction L1 of the main shaft 7 toward the bottom side, the same effect as the inclined hole can be obtained.

  When the axial length of the outer ring spacer 4 can be made relatively long, as shown in FIG. 24, compressed air discharge ports 10 and 10 may be provided at a plurality of different locations in the axial direction of the outer ring spacer 4. Each discharge port 10 is inclined forward in the forward rotation direction of the main shaft 7. Thus, by providing the discharge ports 10 and 10 at a plurality of locations in the axial direction, the driving force of the main shaft 7 can be further assisted.

  25 to 27 show a cooling structure of a bearing device suitable for supporting a main shaft that rotates in both forward and reverse directions, like the main shaft of a machining center. As shown in FIG. 25, the outer ring spacer 4 of this cooling structure is provided with discharge ports 10A and 10B for compressed air at two different locations in the axial direction. One discharge port 10A is inclined forward in the forward rotation direction LA of the main shaft 7 as shown in FIG. 26, and the other discharge port 10B is reverse rotation direction LB of the main shaft 7 as shown in FIG. It is inclined forward. As shown in FIG. 25, an electromagnetic control valve 45 is provided in a path for sending compressed air from the compressed air supply device 14 to the cooling air supply holes 13A and 13B of the housing 6, and this electromagnetic control valve 45 is controlled. Thus, the compressed air is supplied to one of the discharge ports 10A and 10B through the cooling air supply holes 13A and 13B.

  According to this configuration, the driving force of the main shaft 7 can be assisted during both forward and reverse rotations by discharging compressed air from the discharge port 10A during forward rotation of the main shaft 7 and discharging compressed air from the discharge port 10B during reverse rotation. it can. Further, if the compressed air is discharged from the discharge port 10B when the main shaft 7 is stopped from the normal rotation state, and the compressed air is discharged from the discharge port 10A when the main shaft 7 is stopped from the reverse rotation state, the brake of the main shaft 7 is obtained. Can be used.

  FIG. 28 shows an embodiment in which the rolling bearing 1 is a cylindrical roller bearing. In this bearing device, two outer ring spacers 4 (1) and 4 (2) are respectively arranged on both sides of a rolling bearing 1 composed of a cylindrical roller bearing, and two inner ring spacers 5 (1), 5 (2) are respectively arranged. The outer ring 2 and the outer ring spacers 4 (1), 4 (2) are axially positioned by the step 6a of the housing 6 and the end surface cover 40, and the inner ring 3 and the inner ring spacers 5 (1), 5 (2 ) Is positioned by the stepped portion 7a of the main shaft 7 and the nut 43 screwed onto the outer periphery of the main shaft 7.

  Discharge ports 10 (1) and 10 (2) for discharging compressed air for cooling are provided on the inner peripheral surfaces of the outer ring spacers 4 (1) and 4 (2), respectively, and the outer ring spacer 5 (1). , 5 (2) are provided with holes 15 (1) and 15 (2) for receiving compressed air discharged from the discharge ports 10 (1) and 10 (2), respectively. As shown in FIG. 29, the discharge ports 10 (1), 10 (2) and the holes 15 in the outer ring spacers 4 (1), 4 (2) and the inner ring spacers 5 (1), 5 (2) facing each other. The positional relationship between (1) and 15 (2) is a1> b1, a2> b2. Here, a1 and a2 are distances from the end face of the outer ring 2 to the discharge ports 10 (1) and 10 (2), and b1 and b2 are distances from the end face of the inner ring 3 to the holes 15 (1) and 15 (2). is there.

  In the cylindrical roller bearing, since the cylindrical roller as the rolling element 8 is in line contact with the inner and outer rings 3, 2, it is desirable to cool uniformly from both sides of the bearing. Further, when the compressed air discharge ports 10 (1) and 10 (2) are provided in the outer ring spacers 4 on both sides, the cooling air discharged from the discharge ports 10 (1) and 10 (2) on both sides is mutually connected. If it flows toward the rolling bearing 1, cooling air and air oil may accumulate in the bearing and cause overheating. For example, as shown in FIG. 30, when the compressed air discharge port 10 of the outer ring spacer 4 and the hole 15 of the inner ring spacer 5 overlap in the axial direction, the inner ring spacer 5 (1 ), 5 (2) receives the cooling air, and a part of the cooling air flows into the bearing. When the positional relationship between the discharge ports 10 (1), 10 (2) and the holes 15 (1), 15 (2) is determined as described above, cooling for discharging from the discharge ports 10 (1), 10 (2) The compressed air can be effectively used for assisting the driving force of the main shaft 7 and can be discharged smoothly.

  31-34 show an embodiment that is grease lubricated. As shown in FIG. 31, this bearing device J also has an outer ring spacer between the outer rings 2 and 2 and between the inner rings 3 and 3 of the plurality of rolling bearings 1 and 1 arranged in the axial direction, as in the case of the air oil lubricated bearing device. 4 and an inner ring spacer 5 are interposed. An angular ball bearing is applied as each rolling bearing 1. A plurality of rolling elements 8 are interposed between the raceway surfaces of the inner and outer rings 3, 2, and these rolling elements 8 are held by a cage 9 in a circumferentially equidistant manner. In addition, in this bearing device J that is grease lubricated, seal members 31 and 32 that seal the bearing space S1 between the outer ring 2 and the inner ring 3 are attached to both ends of the outer ring 2 in the axial direction.

  This bearing device J is used, for example, to support the main shaft of a machine tool. In this case, as shown in FIG. 33, the outer ring 2 of each rolling bearing 1 is fixed in the housing 6, and the inner ring 3 is fixed to the main shaft 7. Fits to the outer peripheral surface.

The cooling structure of the bearing device J will be described.
In FIG. 31, a radial clearance δ3 is provided between the inner peripheral surface of the outer ring spacer 4 and the outer peripheral surface of the inner ring spacer 5, and the inner ring spacer is provided on the inner peripheral surface of the outer ring spacer 4. A discharge port 10 for supplying compressed air for cooling toward the outer peripheral surface 5 is provided. In this example, as shown in FIG. 33, the number of discharge ports 10 is three, and the discharge ports 10 are equally arranged in the circumferential direction.

  The air discharge direction of each discharge port 10 is inclined forward in the rotational direction L1 of the inner ring 3 (FIG. 31) and the main shaft 7. Each discharge port 10 is linear and is offset from an arbitrary radial straight line L2 in a cross section perpendicular to the axis of the outer ring spacer 4 in a direction orthogonal to the straight line L2 (offset amount OS). It is in.

  As shown in FIGS. 31 and 33, an annular introduction groove 11 for introducing the compressed air A is provided on the outer peripheral surface of the outer ring spacer 4. The introduction groove 11 is provided at an axially intermediate portion on the outer peripheral surface of the outer ring spacer 4 and communicates with each discharge port 10 through a connection hole 11a. Compressed air A is supplied to the introduction groove 11 from a compressed air supply device (not shown) provided outside the bearing device J through a cooling air supply hole 13 provided in the housing 6.

  As shown in FIG. 31, both end portions in the axial direction of the inner ring spacer 5 are obstruction walls 33 projecting to the outer diameter side. In this example, the obstacle wall 33 has a tapered shape in which the protruding amount toward the outer diameter side is larger toward the side closer to the axial rolling bearing 1. Further, a cutout 34 serving as a discharge port for the compressed air A supplied from the discharge port 10 is provided on the axial end surface of the outer ring spacer 4. For example, the notch 34 has a rectangular cross-sectional shape as shown in FIG. 34, and the outer ring 2 of the rolling bearing 1 is disposed adjacent to the outer ring spacer 4, so that the notch 34 is formed between the outer ring spacer 4 and the inner ring spacer. It becomes an opening shape which communicates between the space S2 between the seats 5 and the outside of the bearing device J. In this configuration, in order to assemble the outer ring spacer 4 (in order to prevent interference between the inner periphery of the outer ring spacer 4 and the obstacle wall 33), the inner ring spacer 5 is divided, for example, in the axial intermediate portion. It consists of two inner ring spacer divided bodies.

  As shown in FIG. 32, which is a partially enlarged view of FIG. 31, the outer diameter end of the obstacle wall 33 is opposed to the inner peripheral surface of the outer ring spacer 4 with a slight radial clearance δ4. Further, the end face of the obstacle wall 33 faces the axially inner sealing member 31 with a slight axial clearance δ5. Thereby, the labyrinth seal portion 35 having a labyrinth seal effect is constructed by the seal member 31 and the obstacle wall 33, and the bearing space S1 and the spacer space S2 are separated by the labyrinth seal portion 35.

  In this bearing device J, the cooling compressed air A sent from a compressed air supply device provided outside the bearing device J during operation or the like is discharged from the discharge port 10 of the outer ring spacer 4 to the outer peripheral surface of the inner ring spacer 5. Supplied towards The compressed air A collides with the inner ring spacer 5, then flows axially along the outer peripheral surface of the inner ring spacer 5, and further flows along the tapered outer diameter surface of the obstacle wall 33 of the inner ring spacer 5. It is guided to the radial side and discharged from the notch 34 of the outer ring spacer 5. By guiding the compressed air A to the outer diameter side by the obstacle wall 33, the flow of the compressed air A in the spacer space S2 and the discharge of the compressed air A from the spacer space S2 become smooth. While the compressed air A passes through the spacer space S2, the heat of the bearing device J and the main shaft 7 supported by the bearing device J is taken away. Thereby, the bearing device J and the main shaft 7 are efficiently cooled.

  Further, since the air discharge direction of each discharge port 10 of the outer ring spacer 4 is inclined forward in the rotational direction L1 of the inner ring 3 and the main shaft 7, the discharged compressed air A hits the outer peripheral surface of the inner ring spacer 5. At this time, the jet output of the compressed air A can be given to the inner ring spacer 5 and the effect of driving the main shaft 7 can be expected. This configuration is applied when the rotation direction of the shaft supported by the bearing device J is constant like the main shaft 7 of the machine tool.

  Since the obstacle walls 33 are provided at both axial ends of the inner ring spacer 5, the compressed air A is prevented from flowing into the bearing space S1. Particularly in this embodiment, since the bearing space S1 and the spacer space S2 are separated by the labyrinth seal portion 35, the inflow of the compressed air A into the bearing space S1 can be more effectively prevented. Furthermore, since the compressed air A flows smoothly in the spacer space S2, the internal pressure of the spacer space S2 is lower than the internal pressure of the bearing space S1, and the compressed air A hardly flows into the bearing space S1. For these reasons, the compressed air A can be prevented from flowing into the bearing space S1 as much as possible, and the grease enclosed in the bearing space S1 can be prevented from being removed by the compressed air A. Therefore, a good lubrication state can be maintained.

  In the above embodiment, the discharge port 10 and the notch 34 are arranged at the same circumferential position. However, as in the embodiment shown in FIGS. 35 and 36, the discharge port 10 and the notch 34 are arranged in the circumferential direction. The positions may be shifted. When the circumferential positions of the discharge port 10 and the notch 34 are shifted from each other, the compressed air A supplied from the discharge port 10 to the spacer space S2 flows to the notch 34 along the outer peripheral surface of the inner ring spacer 5. Sometimes, in addition to the movement outward in the axial direction, the movement in the circumferential direction is accompanied, so that the time for the compressed air A to contact the inner ring spacer 5 becomes longer, and the effect of cooling the bearing device J and the main shaft 7 is enhanced.

  FIG. 37 is a cross-sectional view showing a part of a spindle device of a machine tool in which the bearing device shown in FIGS. 35 and 36 is incorporated. Since the configuration of the spindle device is the same as that shown in FIG. 12, the description of each part of the spindle device is omitted. Since the cooling structure of the bearing device J has a high cooling effect on the bearing device J and the main shaft 7 as described above, the main shaft device J can be operated in a high-speed region. For this reason, this bearing apparatus J can be used suitably for support of the main axis | shaft of a machine tool.

  Each of the above embodiments can be configured independently, but the cooling effect is further increased by using each embodiment in combination. In addition to the angular ball bearing and the cylindrical roller bearing, the cooling structure and the cooling method can be applied to a tapered roller bearing using a bearing positioning spacer. The cooling structure and cooling method of the bearing device can also be applied to machine tool devices and turbomachine devices.

DESCRIPTION OF SYMBOLS 1 ... Rolling bearing 2 ... Outer ring 3 ... Inner ring 3a ... Inner ring outer diameter surface 4 ... Outer ring spacer 5 ... Inner ring spacer 5a ... Groove 6 ... Housing 10 ... Discharge port 15 ... Hole 16 ... Air oil supply port 23 ... Projection part 25 ... Nozzle δ2 ... annular clearance

Claims (8)

Between the outer ring of a plurality of rolling bearings arranged in the axial direction and the outer ring spacer and the inner ring spacer is interposed respectively between the inner ring, the outer ring and the outer ring spacer is disposed in the housing, fitting the inner ring and the inner ring spacer is the main axis Bearing device,
The outer ring spacer, discharge port for discharging the compressed air of the cooling-only toward the outer circumferential surface of the inner ring spacer is provided to be inclined forward in the rotational direction, the outer peripheral surface of the inner ring spacer, the ejection A cooling structure of a bearing device in which a plurality of holes arranged in a circumferential direction for receiving compressed air blown at an inclination are provided at positions where compressed air discharged from an outlet is blown . An outer ring spacer and an inner ring spacer are interposed between outer rings and inner rings of a plurality of rolling bearings arranged in the axial direction, the outer ring and outer ring spacers are installed in a housing, and the inner ring and inner ring spacer are fitted to the main shaft. Bearing device,
A discharge port that discharges compressed air toward the outer peripheral surface of the inner ring spacer is provided in the outer ring spacer so as to be inclined forward in the rotation direction, and is discharged from the discharge port on the outer peripheral surface of the inner ring spacer. A plurality of holes arranged in the circumferential direction are provided at positions where the compressed air is sprayed,
A cooling structure for a bearing device in which a groove is provided on an outer peripheral surface of the inner ring spacer. The cooling structure for a bearing device according to claim 1 or 2, wherein the inner ring is made of ceramic . 4. The cooling structure for a bearing device according to claim 1, wherein a groove is provided on an inner peripheral surface of the inner ring spacer. 5. 5. The cooling structure for a bearing device according to claim 1, wherein the outer ring spacer is an air oil that supplies air oil into the rolling bearing separately from a discharge port that discharges the compressed air. A cooling structure for a bearing device having a supply port, the air oil supply port including a protrusion that protrudes into the rolling bearing and faces an outer peripheral surface of the inner ring via an air oil passage annular gap.   6. The cooling structure for a bearing device according to claim 5, wherein the air oil supply port includes a nozzle that discharges air oil to the inner ring on the inner diameter side of the protruding portion. An outer ring spacer and an inner ring spacer are interposed between outer rings and inner rings of a plurality of rolling bearings arranged in the axial direction, the outer ring and outer ring spacers are installed in a housing, and the inner ring and inner ring spacer are fitted to the main shaft. Bearing device,
A discharge port that discharges compressed air toward the outer peripheral surface of the inner ring spacer is provided in the outer ring spacer so as to be inclined forward in the rotation direction, and is discharged from the discharge port on the outer peripheral surface of the inner ring spacer. A plurality of holes arranged in the circumferential direction are provided at a position where the compressed air is sprayed, and the outer ring spacer has an air oil supply port for supplying air oil into the rolling bearing. includes a projecting portion that faces through the annular gap for air-oil passage between the outer peripheral surface of the inner ring projects into the rolling bearing, bearing said air-oil supply port, and the compressed air discharge opening is also used Equipment cooling structure.   The cooling structure for a bearing device according to any one of claims 1 to 7, wherein the rolling bearing is an angular ball bearing, a tapered roller bearing, or a cylindrical roller bearing.

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