JP3488084B2 - Liquid dynamic pressure spindle device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a spindle device for supporting the rotation of a spindle main shaft on which a rotating body such as a grindstone is mounted by means of a dynamic pressure bearing, and in particular, as a lubricating fluid for such a dynamic pressure bearing, a coolant liquid or the like is used. The present invention relates to improvement of a liquid dynamic pressure spindle device using a liquid.

[0002]

2. Description of the Related Art Conventionally, as a dynamic pressure spindle device of this type, Japanese Patent Application Laid-Open Nos. 6-241222 and 6-24 are available.
Those disclosed in Japanese Patent No. 9236, Japanese Patent Laid-Open No. 7-19236, etc. are known. Such a dynamic pressure spindle device is composed of a housing fixed to a spindle head of a machine tool, a spindle main shaft which is connected to a drive means and rotates, and a rotary side member and a fixed side member which face each other through a predetermined bearing gap. And a radial dynamic pressure bearing and a thrust dynamic pressure bearing that rotatably support the spindle main shaft with respect to the housing, and the dynamic pressure of a depth of about 10 to 15 μm is applied to the rotary side member of each dynamic pressure bearing. Generation grooves are formed in a predetermined pattern.

In the hydrodynamic bearing device thus constructed, the lubricating fluid present in the bearing gap of the hydrodynamic bearing is pressurized as the spindle spindle rotates, and the spindle spindle is levitated by the high-pressure fluid lubricating film. It will be in a state, and rotation will be supported in that state. For this reason, only a slight amount of rotational resistance acts on the rotation of the spindle spindle, and vibration during rotation hardly occurs. Therefore, high-speed rotation of 10,000 rpm or more is applied to the spindle spindle. It also has the excellent characteristics that it can be used as well.

Further, in such a dynamic pressure spindle device, since the lubricating fluid is pressurized with the rotation of the spindle main shaft, if the bearing gap between the rotary side member and the fixed side member of each dynamic pressure bearing is too large, The pressure of the lubricating fluid cannot be sufficiently increased in the bearing gap, and the load capacity and rigidity of the spindle main shaft against an external load will be reduced. Therefore, in the above-described conventional dynamic pressure spindle device, the bearing gap is set to about several μm so that the lubricating fluid can be sufficiently pressurized even when the main shaft rotates at a low speed.

Further, as the lubricating fluid which is pressurized in the bearing gap of each dynamic pressure bearing, water or liquid such as coolant for machine tools can be used in addition to gas such as air.
Since the liquid is smaller than the compressibility of the gas, the load capacity and the rigidity against the load of the spindle are improved when the liquid is used as the lubricating fluid. Therefore, assuming that this dynamic pressure spindle device is used for applications where heavy loads act, such as the spindle head of a machine tool, the displacement of the spindle spindle during machining of a workpiece is better when a liquid is used as the lubricating fluid. Can be suppressed,
It can be expected that the machining accuracy of such a work is improved.

[0006]

However, in the conventional dynamic pressure spindle device having such a structure, the bearing gap of each dynamic pressure bearing is provided because the spindle main shaft is supported in the housing in a non-contact manner. Is in communication with the atmosphere outside the housing, and when liquid is used as the lubricating fluid,
There is a problem that the lubricating fluid pressurized in the bearing gap leaks to the outside of the housing and stains the periphery of the dynamic pressure spindle device. Therefore, the conventional dynamic pressure spindle device can be used, for example, in a clean room.
It could not be used in an environment where contamination due to leakage of the lubricating fluid is disliked.

Further, since the lubricating fluid leaks out of the housing through the bearing gap of each dynamic pressure bearing, a large amount of lubricating fluid is required for the operation of this spindle device, which is necessary for maintenance such as supply of lubricating fluid. However, it also had the drawback of increasing operating costs. It is not impossible to collect the leaked lubricating fluid and supply it to the bearing gap again, but it is highly possible that the once leaked lubricating fluid contains dust and cutting powder of the work. If the lubricating fluid is supplied to the bearing gap as it is, these foreign matters are caught in the bearing gap having a width of several μm, and there is a high possibility that the smooth rotation of the spindle shaft will be hindered. Therefore, if the leaked lubricating fluid is to be supplied to the bearing gap again, it is necessary to carefully filter the foreign matter out of the lubricating fluid using a fine mesh filter, which complicates the device and regularly filters. There was a problem that it had to be washed.

On the other hand, in order to prevent such leakage of the lubricating fluid, it is sufficient to mount a seal member in sliding contact with the spindle main shaft on the housing and seal the gap between the spindle main shaft and the housing. As described above, in this dynamic pressure spindle device, since the spindle main shaft rotates at an extremely high rotational speed, when such a seal member is provided, the spindle main shaft expands due to friction heat,
There was a problem that the processing accuracy of the work deteriorates.

The present invention has been made in view of the above problems, and an object of the present invention is to prevent the lubricating fluid from flowing through the gap between the spindle main shaft and the housing even when a liquid is used as the lubricating fluid. It is an object of the present invention to provide a liquid dynamic spindle device capable of operating a spindle main shaft while circulating a small amount of lubricating fluid without leaking.

[0010]

In order to achieve the above object, the liquid dynamic pressure spindle device of the present invention has a housing and a journal portion supported by the housing, and has a rotatable body mounted at one end thereof. The quill portion is fixed to the above-mentioned housing with a spindle main shaft having a connecting portion for driving means at the other end, and opposes the journal portion of the spindle main shaft with a predetermined bearing gap. A bearing ring that composes a radial dynamic pressure bearing, and is provided so as to sandwich the journal portion of the spindle main shaft from its axial direction, and faces the axial end surface of the bearing ring through a predetermined bearing gap, Together with such a bearing ring, a pair of thrust plates forming a thrust dynamic pressure bearing and a lubricating liquid are supplied to the bearing gap of the radial dynamic pressure bearing. A supply flow path for recovering the lubricating liquid supplied to the bearing clearance of the radial dynamic pressure bearing through the bearing clearance of the thrust dynamic pressure bearing, and a clearance formed between each thrust plate and the housing. And a lubricating liquid sealing means for supplying the lubricating liquid flowing out from the bearing gap of the thrust dynamic pressure bearing to the recovery passage.

According to the above technical means, the bearing gap of the radial dynamic pressure bearing, that is, the gap between the bearing ring and the journal portion of the spindle main shaft is the bearing gap of the thrust dynamic pressure bearing, that is, the bearing. Since it communicates with the clearance between the ring and the thrust plate, when the spindle main shaft starts rotating, the lubricating fluid supplied from the supply flow path to the bearing clearance of the radial dynamic pressure bearing is pressurized and thrust dynamic pressure is increased. It flows into the bearing gap of the bearing, is discharged from the bearing gap, and flows into the recovery channel.

At this time, the lubricating liquid discharged from the bearing gap of the thrust dynamic pressure bearing tries to flow into not only the recovery flow passage but also the gap between the thrust plate and the housing. However, in the dynamic pressure spindle device of the present invention. Since the lubricating liquid sealing means supplies the pressurized sealing gas to this gap, the lubricating liquid discharged from the bearing gap of the thrust dynamic pressure bearing does not enter the gap between the thrust plate and the housing. Instead, all the lubricating liquid discharged from the bearing gap can flow into the recovery passage.

Therefore, in this spindle device, the lubricating liquid does not leak to the outside of the housing, and the spindle main shaft can be continuously operated while circulating the lubricating liquid in the passage closed to the outside. Is. Also,
Since the lubricating liquid does not leak to the outside of the housing, and as a result foreign matter such as dust does not enter the lubricating liquid, always keep clean lubricating liquid in the bearing gaps of the radial dynamic pressure bearing and thrust dynamic pressure bearing. It is possible to prevent the trouble that foreign matter is caught in the bearing gap and the rotation of the spindle of the spindle becomes defective, and a filter for filtering the foreign matter from the lubricating liquid is not necessary, which simplifies the device configuration and It is possible to reduce the maintenance work.

In the present invention as described above, in the radial dynamic pressure bearing and the thrust dynamic pressure bearing that support the rotation of the spindle main shaft, the lubricating liquid present in the bearing gap is pressurized as the spindle main shaft rotates, Since the high-pressure fluid lubrication film is formed in the bearing gap, the high-pressure fluid lubrication film is not yet formed when the spindle main shaft starts rotating, and the bearing ring and the journal portion of the spindle main shaft are
There is a concern that the bearing ring and the thrust plate may come into solid contact with each other and damage the bearing ring and the thrust plate. In particular, when the spit spindle spindle is used in a vertically aligned manner, the weight of the spindle spindle is concentrated on the thrust plate, so such solid contact is likely to occur and the spindle spindle is difficult to start. Therefore, from this point of view, it is preferable that the sealing gas is supplied to the gap between the thrust plate and the housing even when the spindle main shaft is started, and the static pressure of the sealing gas acts on the thrust plate. With this structure, even if a sufficient high-pressure fluid lubrication film is not yet formed in the bearing gap of each dynamic pressure bearing, the solid contact between the thrust plate and the housing and the thrust plate and the bearing ring can be effectively performed. It is possible to prevent it, and since the static pressure is applied by utilizing the inherent lubricating liquid sealing means, it is very efficient in that there is no need to add a new pressurizing device. .

Although an electric motor or the like can be used as the drive means for rotating the spindle main shaft of the present invention, this type of spindle device is reluctant to change the axial length of the spindle main shaft due to heat generation. It is necessary to positively prevent the heat generated by the driving means from being transmitted to the spindle main shaft. Therefore, from this point of view, it is preferable that the sealing gas pressurized by the lubricating liquid sealing means is introduced into the motor housing or the like, and the driving means is cooled by the sealing gas.

Further, in the liquid dynamic pressure spindle device of the present invention, since the sealing gas is supplied to the gap between the thrust plate and the housing, the lubricating liquid discharged from the bearing gap of the thrust dynamic pressure bearing is sealed. It will flow into the recovery channel together with the gas. Therefore, if the recovered lubricating liquid is to be supplied from the supply passage to the bearing gap of the radial dynamic pressure bearing again, it is preferable to provide a reservoir tank for separating the recovered sealing gas and the lubricating liquid. In addition, although the lubricating liquid is heated by the shear friction heat in the bearing gap of each dynamic pressure bearing, if the reservoir tank is provided in this way, it is possible to cool the lubricating liquid in such a tank. It is also possible to suppress the temperature rise of the pressure bearings and consequently the thermal expansion of the spindle.

On the other hand, in such a dynamic pressure bearing, when the spindle main spindle is stopped, the lubricating liquid stays in the bearing gap having a width of several μm. Therefore, when the spindle main spindle is stopped for a long time, There is a concern that the spindle main shaft will be stuck to the bearing ring and the thrust plate, making it impossible to start the spindle main shaft. This is especially a concern when a volatile liquid such as a coolant is used as the lubricating liquid. Therefore, from this point of view, the lubricating liquid supplied to the supply passage is pressurized so that the lubricating liquid flows without stagnation in the bearing gap of each dynamic pressure bearing even when the spindle main shaft is stopped. It is preferable to configure. However, in this case, if the applied pressure of the lubricating liquid exceeds the applied pressure of the sealing gas by the lubricating liquid sealing means, the lubricating liquid will leak from the gap between the thrust plate and the housing. For the purpose of the present invention of preventing leakage of the liquid, it is necessary to set the pressure of the sealing gas higher than the pressure of the lubricating liquid.

As another means for preventing the spindle spindle and the bearing ring from sticking to each other while the spindle spindle is stopped, the sealing gas supplied to the gap between the thrust plate and the housing is ejected toward the recovery passage. Then, the bearing gap of the thrust dynamic pressure bearing in the vicinity of the inlet of the recovery passage may be kept at a negative pressure. With this structure, the bearing gap of the thrust dynamic pressure bearing near the inlet of the recovery passageway becomes negative pressure due to the ejection of the sealing gas, so that the bearing gap between the radial dynamic pressure bearing and the thrust dynamic pressure bearing is interposed. The lubricating liquid is sucked toward the inlet of the recovery passage, and it is possible to prevent the lubricating liquid from staying in the bearing gap. Therefore, even if the spindle main shaft is stopped, the sealing liquid is pressurized by the lubricating liquid sealing means, so that the lubricating liquid always flows in the bearing gap of each dynamic pressure bearing, so that the spindle main shaft is prevented from sticking. Is what you can do.

Further, if the spindle main spindle is constantly rotating, the above-mentioned problem of sticking of the spindle main spindle does not occur. Therefore, if the spindle main spindle is rotated at a low speed even when the driving means is stopped, the above-mentioned problem can be solved. It is possible to avoid the problem that the spindle spindle is stuck. In the present invention, in order to completely prevent the leakage of the lubricating liquid, the pressurized sealing gas is supplied even when the spindle main shaft is stopped, that is, even when the drive means is stopped. By doing so, it is possible to constantly rotate the spindle main shaft. That is, a turbine rotor is mounted on the spindle main shaft, and pressurized sealing gas is blown against the turbine rotor to continuously rotate the spindle main shaft at a low speed even when the drive means is not operating. Can be prevented.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The liquid dynamic pressure spindle device of the present invention will be described in detail below with reference to the accompanying drawings. FIG. 1 shows a liquid dynamic pressure spindle device to which the present invention is applied. In the figure, reference numeral 1 is a spindle main shaft on which a grindstone is mounted via a quill shaft (not shown) at the shaft end, and reference numeral 2
Is a housing main body that supports the spindle main shaft 1, reference numeral 3 is a motor that drives the spindle main shaft 1, reference numeral 4 is a motor housing for fixing the motor 3 to the housing main body 2, and reference numeral 5 is the motor housing 4. It is an end housing fixed to the housing main body 2 at a site on the opposite side, and the entire spindle device is fixed to a spindle head or the like of a machine tool via a flange portion 40 formed on the motor housing 4. ing.

The spindle main shaft 1 is rotatably supported by a radial dynamic pressure bearing 6 and a thrust dynamic pressure bearing 7 which will be described later. The journal portion 10 as an inner ring of the radial dynamic pressure bearing 6 and the quill shaft are supported. Mounting hole 1
1 and a connecting portion 13 which penetrates the motor 3 and to which a rotor 31 of the motor is fixed.

The motor 3 for driving the spindle main shaft 1 is housed in the motor housing 4 and is composed of a rotor 31 fixed to the connecting portion of the spindle main shaft 1 and a stator 32 fixed to the motor housing 4. Connector 41 attached to the motor housing 4
A motor drive signal is externally input to the stator 32 via the. A water jacket 42 is provided in the motor housing 4 in order to prevent heat generated by the motor 3 from flowing into the spindle main shaft 1 and expanding the spindle main shaft 1 as much as possible.

As shown in FIG. 2, the radial dynamic pressure bearing 6 which supports the rotation of the spindle main shaft 1 with respect to the housing body 2 has a sleeve 61 fixed to the journal portion 10 of the spindle main shaft 1, as shown in FIG. This sleeve 61
A bearing ring 62 that is loosely fitted to the outside of the housing and fixed to the housing body 2, and a predetermined bearing gap (for example, between the outer peripheral surface of the sleeve 61 and the inner peripheral surface of the bearing ring 62). 5 to 15 μm) are formed. Sleeve 6 facing the inner peripheral surface of the bearing ring 62
As shown in FIG. 3, a herringbone-shaped dynamic pressure generating groove 63 having a depth of about 15 μm is formed on the outer peripheral surface of No. 1, and when the spindle main shaft 1 rotates, the dynamic pressure generating groove 63 is formed. The lubricating fluid present in the bearing gap between the bearing ring 62 and the sleeve 61, that is, the bearing gap of the radial dynamic pressure bearing 6 is pressurized, and a high-pressure fluid lubrication film is formed in the bearing gap. As a result, the spindle main shaft 1 is rotatably supported on the bearing ring 62 in a non-contact state. In this embodiment, the sleeve 61 in which the dynamic pressure generating groove 63 is formed is fitted to the journal portion 10 of the spindle main shaft 1, but the dynamic pressure generating groove 63 is directly formed on the outer peripheral surface of the journal portion 10. However, even if the sleeve 61 is omitted, the radial dynamic pressure bearing 6
Can also be configured.

On the other hand, a pair of thrust dynamic pressure bearings 7 are provided so as to sandwich the radial dynamic pressure bearing 6, and the axial movement of the spindle main shaft 1 is restricted by these thrust dynamic pressure bearings 7, 7. As shown in FIG. 2, the thrust dynamic pressure shaft bearing 7 includes a pair of thrust plates 71 fixed to the spindle main shaft 1 so as to sandwich the journal portion 10 of the spindle main shaft 1 and the sleeve 61.
71 and the above-mentioned bearing ring 62,
A predetermined bearing gap that communicates with the bearing gap of the radial dynamic pressure bearing 6 is formed between the thrust plates 71, 71 and the axial end surface of the bearing ring 62. As shown in FIG. 4, a spiral dynamic pressure generating groove 7 is formed on one surface of the thrust plate 71 facing the axial end surface of the bearing ring 62.
2 is formed with a depth of about 15 μm, and when the spindle main shaft 1 rotates, the groove 72 for generating dynamic pressure intervenes in the bearing gap between the bearing ring 62 and the thrust plate 71, that is, the bearing gap of the thrust dynamic pressure bearing 7. The lubricating fluid is pressurized and a high-pressure fluid lubricating film is formed in the bearing gap. As a result, the spindle main shaft 1 is restricted from moving in the axial direction by the pair of thrust dynamic pressure bearings 7 provided so as to sandwich the bearing ring 62.

In this spindle device, liquid such as water or a coolant for machining is used as the lubricating fluid for the radial dynamic pressure bearing 6 and the thrust dynamic pressure bearing 7, and the lubricating fluid is applied to the bearing ring 62 in the radial direction. From the supply flow path 64 formed so as to penetrate into the radial dynamic pressure bearing 6
It is designed to be supplied to the bearing clearance of. The supply passage 64 is formed at several places in the circumferential direction of the bearing ring 62 and communicates with the circumferential groove 65 formed on the inner peripheral surface of the housing body 2, and the lubrication formed on the housing body 2 is performed. When the lubricating liquid is supplied to the liquid supply port 20, the lubricating liquid flows into each of the supply passages 64 through the circumferential groove 65 and enters the bearing gap of the radial dynamic pressure bearing 6. Further, the supply channel 64 is formed by the bearing ring 62.
Is formed at a position bisected in the axial direction, facing the center of the herringbone-shaped dynamic pressure generating groove 63 formed in the sleeve 61.

Here, the herringbone-shaped dynamic pressure generating groove 63 formed in the sleeve 61, when the spindle main shaft 1 rotates in the direction shown by the arrow in FIG. It is formed as a so-called pump-out type that pressurizes the lubricating liquid toward both ends of the sleeve 61 in the axial direction. Further, the spiral dynamic pressure generating groove 72 formed in the thrust plate 71 is provided when the spindle main shaft 1 rotates in the direction shown by the arrow in FIG. It is formed as a so-called pump-out type in which pressure is applied from the inner diameter to the outer diameter of 71.

Therefore, in this spindle device, when the spindle main shaft 1 starts to rotate, the radial dynamic pressure bearing 6
Since the lubricating liquid existing in the bearing gap of the bearing flows naturally toward the thrust plates 71 arranged at both ends of the bearing ring 62, the supply passage 64 is formed in the bearing gap.
The lubricating liquid flows in naturally from the. Further, since the bearing gap of the radial dynamic pressure bearing 6 communicates with the bearing gap of the thrust dynamic pressure bearing 7, the lubricating liquid pressurized in the bearing gap of the radial dynamic pressure bearing 6 is the bearing of the thrust dynamic pressure bearing 7. It flows into the gap and flows from the inner diameter of the thrust plate 71 to the outer diameter as the spindle 1 rotates. That is, in this spindle device, when the spindle main shaft 1 rotates,
The lubricating liquid is sucked from the supply passage 64 into the bearing gap of the radial dynamic pressure bearing 6 and is discharged from the outer diameter side of the thrust dynamic pressure bearing 7 so that the lubricating liquid can be self-circulated.

On the other hand, in this way, the thrust dynamic pressure bearing 7
In order to collect the lubricating liquid discharged from the bearing gap of the above and to supply it again to each of the dynamic pressure bearings 6 and 7 from the supply passage 64, in the spindle device of the present embodiment, each thrust is provided to the housing body 2 and the end housing 5. The recovery passages 21 and 50 for the lubricating liquid corresponding to the plate 71 are formed, and the lubricating fluid discharged from the bearing gaps of the thrust dynamic pressure bearings 7 is collected in the recovery passages 2.
It flows into 1,50.

However, the thrust plate 71 is rotating together with the spindle main shaft 1, and a gap is formed between the motor housing 4 and the end housing 5 in which each thrust plate 71 is housed and the outer peripheral surface of each thrust plate 71. Therefore, if no measures are taken, the lubricating liquid discharged from the gap between the thrust plate 71 and the bearing ring 62 (the bearing gap of the thrust dynamic pressure bearing 7) flows around the outer periphery of the thrust plate 71, A part of the gas leaks out of the spindle device without flowing into the recovery flow paths 21 and 50.

Therefore, in the spindle device of the present embodiment, a pressurized lubricating liquid sealing gas (for example, air) is applied to the back surface side of each thrust plate 71 constituting the thrust dynamic pressure bearing 7, The lubricating liquid is prevented from leaking out of the end housing 5 or the motor housing 4 without flowing into the recovery passages 21 and 50. That is, FIG.
As shown in FIG. 3, the motor housing 4 is formed with an intake passage 43 for introducing the pressurized sealing gas into the motor housing 4, and the space in the motor housing 4 is pressurized to seal the sealing gas. Is configured to flow into the gap between the thrust plate 71 and the motor housing 4. on the other hand,
An intake passage 51 for introducing a sealing gas is formed on the rear surface side of the thrust plate 71 in the end housing 5, and the pressurized sealing gas also flows into the gap between the thrust plate 71 and the end housing 5. Is configured as follows. Also,
The sealing gas is pressurized by a compressor (not shown) and sent into the intake passages 43 and 51. However, in order to prevent the leakage of the lubricating liquid during the suspension of the spindle main shaft 1, the intake passage 43 is prevented. , 51 is blown.

As a result, in this embodiment, each thrust plate 7
Since the back side of No. 1 has a high pressure due to the sealing gas, the lubricating liquid discharged from the bearing gap of the thrust dynamic pressure bearing 7 does not go around to the back side of the thrust plate 71, and all the lubricant discharged from the bearing gap. The lubricating fluid of the recovery channel 21,
It will flow into 50. As a result, while the sealing gas is operating, the entire amount of the lubricating liquid supplied from the supply passage 64 to the dynamic pressure bearings 6 and 7 can be collected in the collecting passages 21 and 50, and the lubricating liquid It is possible to prevent leakage to the outside of the device.

By passing the sealing gas through the motor housing 4 in this manner, the temperature inside the motor housing 4 can be lowered and the thermal expansion of the spindle main shaft 1 can be avoided. Is.

Further, although this spindle device is assumed to be used with the tip portion 12 of the spindle main shaft 1 directed vertically downward, as described above, from the intake passage 51 of the end housing 5 to the rear surface of the thrust plate 71. When the pressurized sealing gas acts, the static pressure of the sealing gas acts between the thrust plate 71 and the end housing 5, so that the spindle main shaft 1 slightly resists its own weight and moves upward from below. There is also an advantage that the spindle main shaft 1 can be smoothly started to rotate even in the lifted state, even when the high-pressure fluid lubrication film is not formed in the bearing gaps of the dynamic pressure bearings 6 and 7. .

FIG. 5 is a system diagram for supplying the lubricating fluid recovered from the recovery channels 21 and 50 to the supply channel 64 again. As described above, since the high-pressure sealing gas acts on the back side of each thrust plate 71, the sealing gas also flows around the thrust plate 71 and flows into the recovery passages 21 and 50. The lubricating liquid discharged from the bearing gap of the thrust dynamic pressure bearing 7 flows into the recovery passages 21 and 50 together with the sealing gas. Therefore, when supplying the lubricating liquid again to the bearing gaps of the dynamic pressure bearings 6 and 7, it is necessary to separate the lubricating liquid from the sealing gas. Therefore, in the present embodiment, the lubricating liquid and the sealing gas discharged from the spindle device M through the recovery passages 21 and 50 are once introduced into the reservoir tank 8 and the lubricating liquid 80 is stored in the reservoir tank 8. And the lubricating liquid 80
And the sealing gas is separated. Further, since the recovered lubricating liquid is at a high temperature due to the shear friction heat generated in each of the dynamic pressure bearings 6 and 7, a cooling device 81 for the lubricating liquid 80 is installed in the reservoir tank 8 to lower the temperature. By supplying the lubricating liquid to the spindle device M again, the temperature rise of the dynamic pressure bearings 6, 7 and the temperature rise of the spindle main shaft 1 are prevented. A one-way valve 82 is provided in the recovery passageway in order to prevent the recovered lubricating fluid or the like from flowing backward in the recovery passageway when the pressure in the reservoir tank 80 suddenly rises.

As described above, in the spindle device of this embodiment, when the spindle main shaft 1 starts rotating, the lubricating liquid is naturally sucked from the supply passage 64 into the bearing gap of the radial dynamic pressure bearing 6 and at the same time. Since it is discharged from the bearing gap of the thrust dynamic pressure bearing 7, it is not necessary to pressurize the lubricating liquid with a pump or the like when sending the lubricating liquid from the reservoir tank 8 to the supply passage 64. However, when the rotation of the spindle main shaft 1 is stopped, the natural circulation of the lubricating liquid is also stopped. Therefore, when the stopping time is long, the sleeve 61 or the thrust plate 71 and the housing on the spindle main shaft 1 side and the housing due to the evaporation or evaporation of the lubricating liquid. There is also a concern that the bearing ring 62 on the main body 2 side will be fixed and the spindle main shaft 1 will not be able to start rotating.

Therefore, in the spindle device of this embodiment, the reservoir tank 80 is hermetically sealed against the outside air, and a gas such as air pressurized by a compressor (not shown) (lubricating liquid pressurizing gas) is stored in the reservoir tank 80. The lubricating liquid is introduced and pressurized with the lubricating liquid pressurizing gas to be supplied to the bearing gap of the radial dynamic pressure bearing 6. As a result, even when the rotation of the spindle main shaft 1 is stopped, the lubricating liquid flows in the bearing gap between the radial dynamic pressure bearing 6 and the thrust dynamic pressure bearing 7, and the thrust plate 71 and the like are fixed. The problem of can be avoided. Further, by supplying the pressurized lubricating liquid to the bearing gaps of the respective dynamic pressure bearings 6 and 7, a higher-pressure fluid lubrication film is formed in the bearing gaps when the spindle main shaft 1 rotates, so that the spindle main shaft 1 It is also possible to improve the load capacity. However,
When the pressure of the lubricating liquid in the reservoir tank 80 exceeds the pressure of the sealing gas by the compressor, the lubricating liquid wraps around to the back side of the thrust plate 71, and the lubricating liquid leaks out of the spindle device. Therefore, the pressure of the lubricating liquid must be smaller than the pressure of the sealing gas by the compressor. A pressure adjusting valve 83 is provided in the reservoir tank 80 in order to adjust the pressure in the reservoir tank 80.

Further, in the spindle device of the present embodiment, in order to promote the flow of the lubricating liquid while the spindle main shaft 1 is stopped, the sealing gas is jetted into the recovery passages 21 and 50, whereby the outer periphery of the thrust plate 71 is ejected. The bearing clearance of the thrust dynamic pressure bearing 7 on the side is reduced. Specifically, as shown in FIG. 6, an annular cutout groove 72 is provided at the outer peripheral end of the thrust plate 71 facing the bearing ring 62, and the thrust dynamic pressure bearing 7 is discharged from the bearing gap. While forming the storage chamber 73 in which the lubricating liquid is stored, the throttle plate 74 in which the thrust plate 71 and the bearing ring 62 face each other with a very small gap is formed between the storage chamber 73 and the recovery passageway 50. As a result, when the pressurized sealing gas is applied to the back surface side of the thrust plate 71, the sealing gas is jetted into the recovery passageway 50 at high speed, so that the lubricating liquid in the storage chamber 73 is squeezed. It is sucked into the recovery passageway 50 via the, and the storage chamber 73 is depressurized. As a result, even if the spindle main shaft 1 is stopped, as long as the sealing gas acts on the back surface side of the thrust plate 71 by the compressor, the lubricating liquid intervening in the bearing gap of the thrust dynamic pressure bearing 7 Will flow into the decompressed storage chamber 73, and the lubricating liquid supplied from the supply passage 64 to the bearing gap of the radial dynamic pressure bearing 6 can be circulated to the recovery passage 50.

FIG. 7 shows another example for circulating the lubricating liquid using the sealing gas. In this example, a decompression chamber 75 is provided in the middle of the recovery passageway 50, and a branch pipe for guiding a part of the pressurized sealing gas introduced on the back side of the thrust plate 71 to the decompression chamber 75. A passage 76 is formed, and the sealing gas is collected from the decompression chamber 75 and the collection passage 50
It was configured to be ejected. Further, a lubricating liquid storage chamber 73 is formed on the outer peripheral side of the thrust plate 71 as in FIG. As a result, when the sealing gas is jetted into the decompression chamber 75 via the branch pipe line 76, the decompression chamber 75 is pressurized as the pressurized sealing gas flows into the recovery passageway 50 at high speed. The inside is depressurized, and the lubricating liquid in the storage chamber 73 is sucked into the depressurization chamber 75. As a result, similar to the example shown in FIG. 6, as long as the sealing gas is made to act on the rear surface side of the thrust plate 71, even if the spindle main shaft 1 is stopped, The lubricating liquid supplied to the bearing gaps of the radial dynamic pressure bearing 6 and the thrust dynamic pressure bearing 7 can be circulated to the recovery passageway 50.

When the lubricating gas is circulated in the dynamic pressure bearings 6 and 7 by utilizing the sealing gas pressurized in this way, the lubricating liquid sent to the supply passage 64 is not necessarily pressurized by a pump or the like. It does not have to be.

In the spindle device of this embodiment, the compressor supplies the sealing gas even when the spindle main shaft 1 is stopped, that is, when the motor 3 is stopped. It is also possible to rotate the spindle main shaft 1 at a low speed while the 3 is stopped. That is, as shown in FIG. 1, the turbine rotor 14 is attached to the end of the spindle main shaft 1 on the side of the connecting portion 13, and a sealing gas is blown into the turbine rotor 14 from a nozzle 44 attached to the motor housing 4. To be configured. According to this structure, even when the motor 3 does not apply any driving force to the spindle main shaft 1, the turbine rotor 14 rotates the spindle main shaft 1 at a low speed by the constantly supplied sealing gas. Therefore, the sleeve 61 and the bearing ring 62 and the thrust plate 71 and the bearing ring 62 can be prevented from sticking to each other, and the sealing gas is used to prevent the leakage of the lubricating liquid. It is very labor-saving in that it requires no source. When a liquid having a large viscosity such as a coolant liquid is used as the lubricating liquid, the turbine rotor 14 causes the spindle main shaft 1 to have a viscosity of 15 to 30.
By giving a rotation speed of about rpm, a sufficiently high-pressure fluid lubrication film can be obtained in the bearing gap between the radial dynamic pressure bearing 6 and the thrust dynamic pressure bearing 7, and the thrust plate 71 and the bearing ring 6 can be obtained.
There is no problem that 2 causes solid contact.

8 to 13 show another example of the patterns of the dynamic pressure generating grooves 63 and 72 of the radial dynamic pressure bearing 6 and the thrust dynamic pressure bearing 7. The end portion of the dynamic pressure generating groove 63 of the radial dynamic pressure bearing 6 shown in FIG.
8 is not open to both axial end faces, but the dynamic pressure generating groove 63a of the radial dynamic pressure bearing 6 shown in FIG. There is. Further, the end portion of the dynamic pressure generating groove 72 of the thrust dynamic pressure bearing 7 shown in FIG. 4 is not opened to the outer peripheral edge of the thrust plate 71, but the thrust dynamic pressure bearing 7 shown in FIG.
The dynamic pressure generating groove 72a has an end open to the outer peripheral edge of the thrust plate 71. Therefore, these FIG. 8 and FIG.
When the dynamic pressure generating grooves 63a and 72a shown in FIG. 2 are formed in the sleeve 61 and the thrust plate 71, the spindle main shaft 1
The flow rate of the lubricating liquid in the bearing gaps of the respective dynamic pressure bearings 6 and 7 increases when the bearing rotates, and the cooling effect of the spindle main shaft 1 is improved as compared with the dynamic pressure generating grooves 63 and 72 shown in FIGS. 3 and 4. It is possible to raise it. However, as the flow rate of the lubricating liquid increases, the pressure of the lubricating film in the bearing gap decreases, and the load capacity of the spindle spindle 1 decreases slightly.

On the other hand, the dynamic pressure generating groove 63 of the radial dynamic pressure bearing 6 and the thrust dynamic pressure bearing 7 shown in FIGS. 10 and 11.
In b and 72b, a groove that is opened and a groove that is not opened are formed at a constant ratio on both axial end surfaces of the sleeve 61 or on the outer peripheral edge of the thrust plate. As a result, it is possible to suppress a decrease in the load capacity of the spindle main shaft 1 while increasing the flow rate of the lubricating liquid during the rotation of the spindle main shaft 1.

Further, in the dynamic pressure generating groove 63c of the radial dynamic pressure bearing 6 shown in FIG. 12, when the spindle main shaft 1 rotates in the arrow direction, the lubricating liquid is directed toward both axial end faces of the sleeve 61. A so-called pump-out type groove 63d for pressurizing,
A so-called pump-in type groove 63e that pressurizes the lubricating liquid toward the center of the sleeve 61 in the axial direction is formed side by side. Further, the dynamic pressure generating groove 7 of the thrust dynamic pressure bearing 7 shown in FIG.
Also in 2c, a so-called pump-out type groove 72d that pressurizes the lubricating liquid toward the outer peripheral edge of the thrust plate 71 and the thrust plate 7
A groove 72e of a so-called pump-in type that pressurizes the lubricating liquid toward the inner peripheral edge of No. 1 was formed side by side. As a result, the lubricating liquid intervening in the bearing gaps of the dynamic pressure bearings 6 and 7 is pump-out type grooves 63d and 72d and pump-in type grooves 63e and 72e.
Since the pressure is applied toward the boundary portion with, the fluid lubricating film having a sufficiently high pressure is formed at the boundary portion, and the load capacity of the spindle spindle 1 can be improved. is there. However, according to the configuration of the spindle device of the present embodiment in which the lubricating liquid supplied from the supply passage 64 to the bearing gap of the radial dynamic pressure bearing 6 flows toward the bearing gap of the thrust dynamic pressure bearing 7, the sleeve 61 is provided. Axial length L1 of the pump-out type groove 63d formed in the
Must be longer than the axial length L2 of the pump-in type groove 72d. In addition, the lubricant is applied to the thrust dynamic pressure bearing 7
According to the configuration of the spindle device of the present embodiment that discharges from the bearing gap of the pump toward the recovery passages 21 and 50, the radial length R1 of the pump-out type groove 72d formed in the thrust plate 71 is the pump-in. It must be longer than the radial length R2 of the mold groove 72e.

Further, in the spindle device of this embodiment, the spindle main shaft 1 supported by the dynamic pressure bearing rotates at a remarkably high speed (for example, 50,000 rpm), and due to the imbalance of the weight of the spindle main shaft 1, a slight vibration occurs. Even when acting on the spindle main shaft 1, the sleeve 61 and the bearing ring 62 or the thrust plate 71 and the bearing ring 62 come into contact with each other in the dynamic pressure bearings 6 and 7,
Smooth rotation of the spindle main shaft 1 is impaired. For this reason, in this embodiment, as shown in FIG. 1, a pair of balance rings 9 are mounted near both ends of the spindle main shaft 1 and the weight balance of the spindle main shaft 1 is strictly adjusted to prevent vibration during rotation. ing. This balance ring 9
As shown in FIG. 14, the plurality of screw holes 91 are fitted to the spindle main shaft 1 and arranged at predetermined intervals along the circumferential direction.
Is formed, and a plurality of balance screws 93 screwed into the screw holes 91 of the ring body 92, and the weight of the balance screw 93 screwed into each screw hole 91 is By adjusting the balance, the spindle main shaft 1 can be adjusted in balance. The weight of the balance screw 93 can be adjusted by adjusting the balance screw 9
This can be easily performed by cutting the length of 3.

Therefore, in the present embodiment, based on the mechanically measured weight balance of the spindle spindle 1, the screw 93 at the corresponding position is taken out of the balance screws 93 screwed on the circumference of the balance ring 9. If the work such as grinding or replacing with a long balance screw 93 is performed, the weight balance of the spindle spindle 1 can be easily optimized, and the spindle spindle 1 can be rotated at high speed without vibration. is there.

[0046]

As explained above, according to the liquid dynamic pressure spindle device of the present invention, the rotation of the spindle main shaft is supported by the dynamic pressure bearing using the liquid as the lubricating fluid, and the gap between the thrust plate and the housing is provided. It is possible to prevent the lubricating liquid from leaking to the outside of the housing from the gap by operating the pressurized sealing gas against the lubricating liquid. It is possible to continuously operate the spindle spindle while circulating it, and it is possible to always supply clean lubricating liquid to the bearing clearances of the radial dynamic pressure bearing and thrust dynamic pressure bearing. It is possible to avoid troubles such as poor rotation.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of a liquid dynamic pressure spindle device of the present invention.

FIG. 2 is an enlarged view of a bearing portion of the spindle device according to the embodiment.

FIG. 3 is a diagram showing a dynamic pressure generating groove of the radial dynamic pressure bearing according to the embodiment.

FIG. 4 is a diagram showing a dynamic pressure generating groove of the thrust dynamic pressure bearing according to the embodiment.

FIG. 5 is a system diagram showing a circulation path of a lubricating liquid.

FIG. 6 is a diagram showing an embodiment for circulating a lubricating liquid using a sealing gas.

FIG. 7 is a diagram showing another example for circulating a lubricating liquid using a sealing gas.

FIG. 8 is a view showing a second embodiment of the dynamic pressure generating groove of the radial dynamic pressure bearing.

FIG. 9 is a view showing a second embodiment of the dynamic pressure generating groove of the thrust dynamic pressure bearing.

FIG. 10 is a view showing a third embodiment of the dynamic pressure generating groove of the radial dynamic pressure bearing.

FIG. 11 is a view showing a third embodiment of the dynamic pressure generating groove of the thrust dynamic pressure bearing.

FIG. 12 is a view showing a fourth embodiment of the dynamic pressure generating groove of the radial dynamic pressure bearing.

FIG. 13 is a view showing a fourth embodiment of the dynamic pressure generating groove of the thrust dynamic pressure bearing.

FIG. 14 is an exploded perspective view showing a balance ring mounted on a spindle main shaft.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Spindle main shaft, 2 ... Housing body, 3 ... Motor (driving means), 8 ... Reservoir tank, 9 ... Balance ring, 14 ... Turbine rotor, 62 ... Bearing ring, 64 ...
Supply channel 21, 51 ... Recovery channel 71 ... Thrust plate

Continuation of the front page (56) Reference JP-A-10-96417 (JP, A) JP-A-6-249236 (JP, A) JP-A-7-217748 (JP, A) JP-A-3-121294 (JP , A) Actual Development Sho 55-168761 (JP, U) (58) Fields investigated (Int.Cl. ⁷ , DB name) F16C 17/00-17/26 F16C 33/00-33/28 F16C 33/74 B23Q 1/00 B23B 19/02 B24B 41/04

Claims (7)

(57) [Claims] 1. A spindle main shaft having a housing, a journal portion supported by the housing, a quill portion on which a rotated body is mounted, and a spindle main shaft having a connecting portion for driving means at the other end, A bearing ring that is fixed to the housing and faces the journal portion of the spindle main shaft through a predetermined bearing gap, and that forms a radial dynamic pressure bearing together with the journal portion, and the journal portion of the spindle main shaft. A pair of thrust plates that are provided so as to be sandwiched from the axial direction, and that face the axial end surface of the bearing ring with a predetermined bearing gap, and that form a thrust dynamic pressure bearing together with the bearing ring; A supply channel for supplying the lubricating liquid to the bearing gap of the radial dynamic pressure bearing and the thrust of the lubricating liquid supplied to the bearing gap of the radial dynamic pressure bearing. A pressurized sealing gas is supplied to the recovery flow path for recovery through the bearing gap of the dynamic pressure bearing and the gap formed by each thrust plate and the housing, and flows out from the bearing gap of the thrust dynamic pressure bearing. A liquid dynamic pressure spindle device comprising a lubricating liquid sealing means for guiding the lubricating liquid to the recovery passage. 2. The liquid dynamic spindle device according to claim 1, wherein the sealing gas supplied between the thrust plate and the housing exerts a static pressure on the thrust plate when the spindle is started. A liquid dynamic pressure spindle device characterized by: 3. The liquid dynamic pressure spindle device according to claim 1, wherein the sealing gas supplied between the thrust plate and the housing cools the drive means. . 4. The liquid dynamic spindle device according to claim 1, wherein the lubricating liquid discharged together with the sealing gas from the recovery passageway is separated from the sealing gas and sent again to the supply passageway. A liquid dynamic pressure spindle device comprising: 5. The liquid dynamic spindle device according to claim 1, wherein the lubricating liquid supplied to the supply passage is pressurized. 6. The liquid dynamic pressure spindle device according to claim 1, wherein the sealing gas is jetted into a recovery passage, and a bearing gap of a thrust dynamic pressure bearing near the inlet of the recovery passage is maintained at a negative pressure. A liquid dynamic pressure spindle device. 7. The liquid dynamic pressure spindle device according to claim 1, wherein a turbine rotor is mounted on the spindle main shaft, and a pressurized sealing gas is blown to the turbine rotor. Liquid dynamic pressure spindle device.