JPS5814566B2 - Spindle device using spherical bearings - Google Patents

Description

[Detailed description of the invention] The present invention relates to a spindle device using a spherical bearing.

Many conventionally known bearings such as sliding bearings, rolling bearings, and fluid bearings have only a single function as radial bearings or thrust bearings.

Further, examples of bearings having the functions of both a radial bearing and a thrust bearing include conical bearings and hemispherical bearings.

All of these bearings can only handle radial loads and unidirectional thrust loads.

For this reason, two bearings are usually combined on the front or back to receive thrust loads in two directions, and are used in combination with a radial bearing.

In a rotating device using a bearing as described above, the frictional heat generated by the rotation of the shaft is radiated through the shaft and the housing, but it is better to radiate heat from the housing.
In the case of rolling bearings, the temperature of the inner ring and rolling elements is higher than that of the outer ring.

Since the expansion of the shaft under the influence of this heat is supported by the thrust bearing, the bearing is designed to have a clearance or to have a negative clearance, that is, a preload is applied by a spring.

An object of the present invention is to provide a spherical bearing that can receive radial loads and thrust loads in both directions, is less affected by thermal expansion of the shaft, has self-aligning action, and is extremely easy to assemble and adjust. To obtain a spindle device using

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Before describing embodiments based on the present invention with reference to the drawings, the principle spindle device on which the technical idea of the present invention is based will be described.

First, the basic structure will be explained.

In FIG. 1, a sphere 1 has a hole drilled through the center of the sphere, and is pivoted to one end of a shaft 2 through the hole of the sphere 1.

The spherical bearing 3 consists of two divided spherical seats 3a and 3b each having a concave spherical bearing surface formed to correspond to the convex spherical surface of the sphere 1, and most of the convex spherical surface except for the vicinity of the shaft 2 is In addition, the spherical body 1 is rotatably supported with a static pressure fluid interposed between the spherical body 1 and the spherical body 1.

Further, the radial bearing 4 pivotally supports the other end of the shaft 2 which is spaced apart from the spherical bearing 3.

The spherical bearing 3 and the radial bearing 4 are each fixedly held by a housing 5.

For convenience of explanation, the radial bearing 4 is illustrated as a known radial ball bearing, but details will be described later with reference to FIG. 2.

When a shaft having a spherical body configured as described above is rotated within a spherical bearing, the center of the spherical body coincides with the center of the spherical bearing, so that the shaft can be centered to a certain extent freely.

It has a so-called self-aligning effect. Furthermore, one spherical bearing has the role of one radial bearing and two thrust bearings, so there is no need to arrange thrust bearings at both ends.

Therefore, since the shaft is arranged with a spherical bearing, the elongation of the shaft due to thermal expansion can be extended toward the radial bearing, thereby preventing various inconveniences from occurring.

FIG. 2 shows details of the radial bearing 4 in the first example.

That is, in FIG. 2, a cylindrical support 6 is fitted and fixed into the inner hole of the housing 5 with one opening surface flush with the end surface of the housing 5.

Approximately at the center of the inside of this support 6 is a concave spherical seat formed by carving out the inside of this support 6, and the hemispherical bearing 7 into which the shaft 2 is coaxially inserted so as to be able to slide freely is attached to the concave spherical surface. It is supported by a seat.

Further, an annular plate 9 is screwed into the inner side of the support 6 so as to surround the shaft 2 on the one open surface side of the support 6 .

Three screws 8 passing through the plate 9 and having their tips touching the flat surface of the hemispherical bearing body 7 are arranged and screwed together at equal angles to form an alignment holding means. There is.

In this first embodiment, the concentricity of the shaft between the spherical bearing 3 and the support body 6 is achieved by adjusting the tips of the three screws 8 by pressing them against the flat surface of the hemispherical bearing body 7. Support, ie alignment, can be achieved and the hemispherical bearing body 7 can be fixed to the support body 6.

Therefore, machining of the shaft, machining of the housing, installation, etc. are easier than in the past, and high accuracy is maintained because the housing is fixed.

The above is an explanation of the device that serves as the mother's womb.

Next, an embodiment of the present invention will be described.

As shown in FIG. 3, the shaft 21 has a tapered part 22 in one part of the shaft whose diameter gradually decreases toward the other part, and the shaft 21 has a tapered part 22 that gradually becomes smaller in diameter toward the other part, and the shaft 21 has a tapered part 22 that gradually decreases in diameter toward the other part. Male thread part 23
is engraved.

The sphere 24 has a tapered hole 25 that closely fits into the tapered portion 22, and is fixed to the tapered portion 22 by a nut 26 screwed onto the male threaded portion 23.

Note that the center point C1 of the sphere 24 is aligned with the axis X of the shaft 21.
- It is located on X.

The spherical bearing 27 that supports the spherical body 24 so that the shaft 21 can rotate about the axis X-X of the shaft holds the spherical body 24 between two divided spherical seats 27a and 27b. It is configured.

The spherical seats 27a and 27b are fixed to each other by screws 28.

Further, the spherical seats 27a and 27b have substantially concave hemispherical bearing surfaces 29a and 29b, respectively, and these bearing surfaces are substantially concave and surround the outer peripheral surface of the spherical body 24 with a slight gap. It forms a spherical surface.

Furthermore, holes 30 and 31 are formed in the spherical seats 27a and 27b, respectively, through which the nut 26 and the tapered portion 22 can be inserted freely.

Furthermore, a plurality of air supply passages 32, for example twelve, are formed in the spherical bearing 27, and these are connected to the bearing surfaces 29a, 2.
It communicates with air supply nozzles 33a and 33b that open at 9b.

These air supply nozzles 33a and 33b are arranged equiangularly apart from each other and are bored toward the center C1 of the sphere 24.

An air supply ring 35 having an air supply hole 34 is airtightly fixed to the spherical seat 27a of the hydrostatic spherical bearing 27.

An annular groove 36 communicating with the air supply passage 32 is provided in the inner peripheral wall of the air supply ring 35 .

A pipe 37 connected to a known compressed air supply device (not shown) is screwed into the air supply hole 34 .

Further, the other end of the spherical seat 27a of the spherical bearing 27 is held by a housing 38.

A static pressure radial bearing 39 is provided at the other end of the housing 38.
is installed.

The hydrostatic radial bearing 39 pivotally supports the other end of the shaft 21 that is spaced apart from the hydrostatic spherical bearing 27 .

The radial bearing 39 is connected to the stepped hole 3 of the housing 38.
8a, and a hemispherical bearing body 41 that supports rotation of the shaft 21.

The support body 40 has a cylindrical shape with a through hole 42 that is sufficiently larger than the diameter of the shaft 21, and a concave hemispherical recess 43 is formed in one end surface of the cylinder.

On the other hand, the hemispherical bearing body 41 is a hemisphere supported on the inner wall of the recess 43, and the flat surface of the hemisphere is finished smooth, and the axis passing through the center of the sphere perpendicularly through the flat surface of the hemisphere. A bearing hole 45 is bored through rotatably through 21,
Its inner wall constitutes the hydrostatic radial bearing surface.

An air supply plate 47 is provided on the flat surface of the hemispherical bearing body 41 and has a through hole 46 that sufficiently escapes the shaft 21.
is fixed with a screw (not shown).

The hemispherical bearing body 41 is provided with a plurality of air supply passages 49 each having a nozzle 48 .

The nozzles 48 are annularly opened in the peripheral wall of the bearing hole 45 at equal intervals and in a constant direction perpendicular to the axis XX of the shaft 21.

Further, one part of each air supply passage 49 that communicates with the nozzle 48 communicates with an annular groove 50 provided in the flat surface of the hemisphere. It communicates with the pores 51.

A plug 53 is screwed into the air supply hole 51 to connect a hose 52 extending from a compressed air supply device (not shown).

On the other hand, the support body 40 is provided with a plurality of air supply passages 55 having nozzles 54 opening in the concave hemispherical depressions 43.

The nozzles 54 are arranged at regular intervals, and are pierced toward the center point C2 of the hemispherical surface 43.

The air supply passage 55 is a stepped hole 38a of the housing 38.
are connected to annular grooves 56 provided on the inner circumferential surface of the pipes, respectively, and receive air supply via a pipe 57 from a compressed air supply device, also not shown.

The housing 38 is provided with a gap 58 formed between the housing and the hydrostatic spherical bearing 27, and a discharge hole 59 for discharging the supplied compressed air.

Further, an end plate 60 having a through hole 60a is attached to a screw 61 at the end of the housing 38 on the side of the hydrostatic radial bearing 39.
Fixed by

Three springs 62 are interposed equally on the circumference between the end plate 60 and the air supply plate 47 to form an alignment holding means, and the hemispherical bearing body 41 is the support 4
It is pressed against the hemispherical surface 43 of 0.

With the above configuration, when compressed air is supplied from the compressed air supply device (not shown) to the air supply ring 35 via the pipe 37, the compressed air is transferred to the annular groove provided in the air supply ring 35. 36, the air supply passage 32 of the spherical bearing 27, and is ejected from the nozzles 33a and 33b.

The air ejected from the nozzles 33a, 33b forms a uniform film of air between the bearing surfaces 29a, 29b and the outer peripheral surface of the sphere 24, and the sphere 24 is moved between the bearing surfaces 29a, 29b.
Raise it above 9b.

Therefore, the center C1 of the sphere 24 is located at the bearing surface 29a.
, 29b, the spherical body 24 is supported at the spherical center of the bearing surfaces 29a, 29b of the hydrostatic spherical bearing 27.

The air ejected from the nozzles 33a and 33b is discharged through the holes 31, 30, the gap 58, and the discharge hole 59.

On the other hand, when compressed air is sent to the nozzle 54 via the pipe 57 and the air supply passage 55, the hemispherical bearing body 41 resists the force of the spring 62 and moves into the depression 43 (semi-concave spherical surface) of the support body 40.
It floats more easily, becomes easier to rotate, and operates to float while maintaining a uniform gap.

Next, when compressed air is supplied from a compressed air supply device (not shown) to the air supply holes 51 of the air supply plate 47, the compressed air is passed through the annular groove 50 of the hemispherical bearing body 41, through each air supply passage 49, and then to the nozzle 48. It is ejected from.

The compressed air ejected from the nozzle 48 forms a uniform film of air between the inner circumferential wall of the bearing hole 45 and the outer circumferential surface of the shaft 21, so that the hemispherical bearing body 41 maintains a certain gap with the shaft 21. The shaft 21 is held in a state where the center of the bearing hole 45 of the hemispherical bearing body 41 and the axis X-X of the shaft 21 are aligned.
Acts to support.

The compressed air ejected from the nozzle 48 is transmitted to the hole 46.
The air is discharged to the outside air through the hole 42, and the air discharged from the hole 42 is discharged to the outside air through the discharge hole 59.

At this time, the hemispherical bearing body 41 rotates easily, and the compressed air jetted from the nozzle 48 causes the shaft 21 to rotate.
automatically aligned to

Next, when the amount of compressed air supplied to the nozzle 54 is gradually reduced and stopped, the hemispherical bearing body 41 remains aligned with the shaft 21 and the spring 6
When the two, which are pressed against the concave spherical surface of the recess 43 and rubbed together in advance with a pressing force of 2, come into close contact, they are substantially fixed to each other.

Therefore, the bearing clearance between the shaft 21 and the bearing hole 45 of the hemispherical bearing body 41 becomes uniform.

Note that each nozzle 33a, 33b of the hemispherical bearing body 41 of the hydrostatic spherical bearing 27 and the hydrostatic radial bearing 39,
Compressed air is constantly blown out from 48 during operation.

Therefore, this device can fully demonstrate the performance of a hydrodynamic bearing, and is particularly suitable for high-speed rotation.

As described in detail above, the present invention uses a spherical bearing that covers most of the sphere to control the movement of the axis in each of the radial and two-direction thrust directions through a fluid, using a shaft having a nearly perfect sphere. In addition to regulating the accuracy in the radial and thrust directions, that is, the backlash can be made to the same accuracy. This allows radial loads and thrust loads to be supported with the same accuracy, making it suitable for not only light loads but especially heavy loads. High rotational accuracy can be obtained even with respect to

In addition, since most of the clearance between the sphere and the bearing surface of the spherical bearing that supports the sphere is the same, it is easy to create a high-precision hydrostatic fluid bearing structure, making it easy to rotate at high speeds. can get.

Furthermore, since the center of the sphere coincides with the center of the bearing surface, it has a self-aligning effect, and the alignment holding means makes alignment easy, and since the hemispherical bearing body is fixed, high accuracy is maintained during operation. The bearing device is maintained.

Furthermore, when adjusting the alignment, the hydrostatic radial bearing that pivotally supports the shaft at a position spaced apart from the above-mentioned hydrostatic spherical bearing has the following problems: Due to the coaxial action of the hemispherical bearing body as a static pressure bearing on the shaft due to the fluid ejected from the body, the bearing hole of the hemispherical bearing body and the shaft are automatically aligned while maintaining a uniform bearing clearance. By gradually decreasing and stopping the fluid ejection from the support while maintaining the above-mentioned condition, the convex hemispherical surface of the hemispherical bearing body is gradually pressed against the concave hemispherical surface of the support by the spring force serving as an alignment means, and the hemisphere is formed. The shaped bearing body and the support body are fixed.

Therefore, the alignment of the shaft, the hydrostatic spherical bearing, and the hydrostatic radial bearing can be performed automatically without any skill required, and since the hemispherical bearing body is fixed, the performance of the hydrodynamic bearing is improved. By sufficiently maintaining and demonstrating stable, high-precision, high-speed rotation, it is easy to achieve.

Further, expansion of the shaft due to heat can be released to the radial bearing side.

Note that the present invention is not limited to the embodiments described above, and can be implemented with various modifications without changing the gist thereof.

[Brief explanation of the drawing]

Figure 1 is a cross-sectional view showing the structure of a main shaft using a basic spherical bearing in order to understand the present invention, Figure 2 is a cross-sectional view of the main part showing the alignment mechanism of a radial bearing, and Figure 3 is a cross-sectional view of the main shaft using a basic spherical bearing. FIG. 1 is a cross-sectional front view showing one embodiment of the invention. 21...axis, 24...sphere, 27...
... Hydrostatic spherical bearing, 29a, 29b ... Bearing surface, 38 ... Housing, 39 ...
Hydrostatic radial bearing, 40...Support, 41...
... Hemispherical bearing body, 43 ... Recess, 45
...Bearing hole, 54...Nozzle, 62.
...Alignment holding means.

Claims (1)

[Claims] 1 A shaft having a spherical body at one end, and a static pressure that surrounds the spherical body with a concave spherical bearing surface formed in a shape corresponding to the convex spherical surface of the spherical body and rotatably supports the shaft via a hydrostatic fluid. It has a spherical bearing and a bearing hole through which the shaft portion of the shaft is inserted, and the outer surface is formed into a hemispherical surface coaxial with the bearing hole, so that the shaft can rotate freely via hydrostatic fluid at a position separated from the sphere. a hemispherical bearing body supported by a hemispherical bearing body; and a support body having a concave spherical recess corresponding to the hemispherical surface of the hemispherical bearing body, and a support body provided with a nozzle opening in the concave spherical surface to eject fluid. A hydrostatic radial bearing, a housing for holding the hydrostatic spherical bearing and the hydrostatic radial bearing, and an alignment holding means for pressing the hemispherical bearing body against the support, the support being The hemispherical bearing body is levitated by the ejected fluid, the hydrostatic spherical bearing and the hydrostatic radial bearing are aligned via the shaft supported by the hydrostatic fluid, and the ejected fluid is stopped to maintain the alignment. A spindle device using a spherical bearing, characterized in that it maintains an aligned state by cooperating with the spindle device.