JPH06155106A - Sliding body support structure - Google Patents

Abstract

(57) [Abstract] [Purpose] When the sliding body is stationary or driven at low speed, static pressure oil is supplied to the static pressure pocket to maintain static rigidity, and the sliding body slides at high speed. In this case, the dynamic pressure oil is supplied into the dynamic pressure pocket through the communication passage to secure the rigidity of the sliding body due to the dynamic pressure. [Structure] A shaft 2 is slidably supported on an inner peripheral surface of a bearing metal 3 with a predetermined gap 5, and a static hydraulic pressure is applied to the inner peripheral surface of the bearing metal 3 from a hydraulic pressure supply source through a throttle 16. 1 pocket 11 is provided. Further, the housing 1 is provided with a supply port 23 for supplying a dynamic pressure from a hydraulic pressure supply source. Further, the first pocket 11 and the second pocket 12 are connected to each other by a communication passage 13
To communicate with each other.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a support structure for a sliding body such as a pressure fluid journal bearing used in a spindle device of a machine tool.

[0002]

2. Description of the Related Art Conventionally, in a spindle device of a machine tool or the like, a pressure fluid journal which is adapted to support a shaft by supplying a pressure fluid made of lubricating oil to a gap between opposed surfaces of a shaft and a bearing metal. Bearings are widely used.

[0003]

Among the journal bearings of this type, one having a pocket portion and supplying a pressure fluid to the pocket portion through a throttle is called a hydrostatic bearing. This hydrostatic bearing exhibits high rigidity even when the shaft is stopped. On the other hand, a hydrodynamic bearing is one in which a pressure fluid is supplied to the gap between the shaft and the bearing metal without providing a pocket without a throttle.
This dynamic pressure bearing exhibits high rigidity at high speed rotation,
Hardly exerts rigidity when stopped and rotating at low speed.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above problems existing in the prior art and to provide a supporting device for a sliding body which can increase rigidity at the time of stop, low speed and high speed.

[0005]

In order to achieve the above object, the present invention supports a movable support against a sliding surface of a fixed support, and a pressure fluid from a pressure fluid supply source is provided between them. A first pocket for forming a hydrodynamic land having a predetermined gap for ensuring a given dynamic pressure, and for securing a static pressure rigidity to which a pressure fluid is applied from a pressure fluid supply source on a sliding surface of a fixed support. And a second pocket, a throttle is provided between the first pocket and the pressure fluid supply source, and the first pocket is arranged inside the dynamic pressure land.
The means for connecting the pocket and the second pocket by a communication passage is adopted.

[0006]

In this invention, when the pressure fluid is supplied from the pressure fluid supply source to the first pocket, the pressure in the first pocket rises, and at the same time, the pressure in the second pocket rises due to the communication passage. Therefore, the pressure fluid is positively discharged from the second pocket having a small land area of the sliding surface between the fixed support and the movable support, which is easy to discharge the pressure fluid in the pocket, that is, the second pocket. The pressure change in the first pocket having the same pressure as the above increases sharply as the gap becomes smaller in proportion to the change in the gap due to the load variation acting on the movable body. For this reason, if the length of the land in the gap on the second pocket side or the amount of reduction is appropriately designed, the static rigidity of the movable body on the first pocket side, which is large in size and difficult to discharge pressure fluid, increases. Therefore, even when the movable body does not slide and is in a stationary state or a low speed state, the static rigidity of the movable body with respect to the fixed support body is maintained by the pressure fluid supplied to the first pocket and the pressure fluid supplied to the second pocket. .

When there is no communication passage for communicating the first pocket and the second pocket, the static stiffness pressure fluid supplied to the first pocket provides a certain degree of static stiffness.
Since the pressure change in the first pocket does not react sensitively to the above-mentioned change in the gap, sufficient static rigidity cannot be obtained.

When the sliding speed of the movable body with respect to the fixed support body is high, dynamic pressure is generated by the pressure fluid supplied from the first pocket to the gap of the dynamic pressure land, and the movable body is supported with high rigidity. It

Further, according to the present invention, in addition to the second pocket for securing static pressure, the first pocket for securing static rigidity is also provided inside the dynamic pressure land having a predetermined gap for securing dynamic pressure. The region for ensuring the rigidity and the region for ensuring the dynamic rigidity can be made substantially the same, so that the movable support can be stably supported as compared with the case where the regions are separated.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is embodied in a pressure fluid journal bearing will be described below with reference to FIGS.

As shown in FIG. 2, the housing 1 is formed in a substantially cylindrical shape and is mounted on a spindle head or the like of a machine tool. The shaft 2 as a movable support is rotatably supported in the housing 1 through a pair of front and rear bearing metals 3, 4 as fixed supports, and the outer peripheral surface of the shaft 2 and the bearing metals 3, 4 are supported.
Predetermined gaps 5 and 6 are formed between the surfaces facing the inner peripheral surface of the. The chamber 7 is provided in the housing 1 between the two bearing metals 3 and 4, and the rear end of the gap 5 and the front end of the gap 6 communicate with the chamber 7.

A mounting hole 2a is formed at the front end of the shaft 2, and a tool 8 such as a rotary grindstone is removably mounted in the mounting hole 2a. The pulley 9 is fixed to the rear end of the shaft 2, and the rotational force of a motor (not shown) is transmitted to the shaft 2 via the belt 10 and the pulley 9.

As shown in FIG. 1, first static pressure pockets 11 are formed at three locations at equal intervals (120 degrees) on the inner peripheral surface of the front bearing metal 3 as shown in FIG. .
Further, as shown in FIG. 3, second hydrostatic pockets 12 are formed at three locations on the inner peripheral surface of the bearing metal 3 so as to be positioned in front of the first hydrostatic pocket 11. The first and second static pressure pockets 11 and 12 are connected to the communication passage 1 respectively.
3 communicate with each other.

Further, each of the first static pressure pockets 11 is provided with one supply port 1 through a conduction path 14 provided in the bearing metal 3 and an annular groove 1b formed on the entire inner peripheral surface of the housing 1.
It is connected to 5. A diaphragm 16 is provided at each pocket side end of the conduction path 14. Further, as shown in FIG. 2, the supply port 15 is connected to a hydraulic pump 18 as a pressure fluid supply source via a pipe 17, and the hydraulic pump 18 is connected to an oil tank 20 via an oil cooler 19. There is.

On the other hand, as shown in FIG. 1, dynamic pressure lands 21 are formed on the inner peripheral surface of the bearing metal 3 so as to be located on both front and rear sides of the first static pressure pocket 11. Further, the second static pressure pocket 12 is connected to one supply port 23 provided in the housing 1 through a conduction path 22 and an annular groove 1a formed on the entire inner peripheral surface of the housing 1.
The communication passage 13 includes the conduction passage 22 and the first static pressure pocket 11.
Is intervened between.

The supply port 23 is connected to the hydraulic pump 18 via a pipe line 24. An on-off valve 25 is provided in the middle of the pipeline 24. The opening / closing valve 25 is opened / closed by an operation signal from the control device 26. The rotation signal of the shaft 2 output from the rotation sensor 27 is input to the control device 26. or,
The control device 26 is provided with a setting device 28, which outputs an opening operation signal to the opening / closing valve 25 when the rotation speed of the shaft 2 exceeds a predetermined value.

An annular groove 31 is formed on the inner peripheral surface of the bearing metal 3 in proximity to the second static pressure pocket 12, and the groove 31 is one discharge formed on the bearing metal 3 as shown in FIG. It is connected to a discharge port 33 formed in the housing 1 through a passage 32. The discharge port 33 is connected to the oil tank 20 via a pipe line 34.

Pocket 1 provided on the side of the bearing metal 3
1, 12, communication passage 13, supply port 15, supply port 2
As shown in FIG. 2, 3 is also formed symmetrically on the bearing metal 4 side with respect to the bearing metal 3 side.

As shown in FIG. 2, a flange 35 is integrally formed near the rear end of the shaft 2, and the flange 35 is held by a seal cover 36 attached to the rear end surface of the housing 1. Nozzles 37 and 38 are supported on the inner facing surface of the seal cover 36 toward the flange 35. Both nozzles 37, 38 are communicated with each other by a communication passage 39, and the communication passage 39 is communicated with the supply port 15 by a conduction passage 40.

Next, the operation of the journal bearing constructed as described above will be described. Now, when the hydraulic pump 18 is started in the state where the shaft 2 is stopped or in the low speed rotation state, the lubricating oil is passed through the pipe line 17 through the supply port 15, the annular groove 1b, the conduction line 14 and the throttle 16. It is supplied into the first static pressure pocket 11. Further, the lubricating oil is supplied from the first static pressure pocket 11 through the communication passage 13 into the second static pressure pocket 12. Therefore, the pressure in the first static pressure pocket 11 increases, and at the same time, the pressure in the second static pressure pocket 12 also increases. Therefore, the pressure oil is positively discharged from the second pocket 12 having a short land for easily discharging the pressure oil in the pocket, so that the axial length of the land 12a of the second pocket 12 or the passage of the throttle 16 is increased. If the area is designed appropriately, the pressure change of the first static pressure pocket 11 having the same pressure as the second static pressure pocket 12 will rapidly increase in proportion to the change of the gaps 5 and 6, resulting in the discharge of the pressure oil. Bearings 3 and 4 on the side of the first static pressure pocket 11 that are difficult to perform
The static rigidity of is increased. Therefore, even when the shaft 2 does not slide and is stationary or at a low speed, the pressure oil supplied into the first static pressure pocket 11 and the pressure fluid supplied to the second static pressure pocket cause the shaft 2 to move against the bearing metals 3 and 4. Static rigidity is maintained. That is, the lubricating oil having a predetermined pressure is supplied to each of the static pressure pockets 11 and 12, and the shaft 2 is attached to each pocket 1
The bearings 3 and 4 are supported by the pressure oils in 1 and 12 from the inner peripheral surfaces of the bearing metals 3 and 4 with predetermined clearances 5 and 6, and a predetermined static rigidity is obtained. In this state, the communication path 40 to the communication path 3
Lubricating oil having a predetermined pressure is supplied to the nozzles 37 and 38 through 9, so that high-pressure lubricating oil is supplied to the front and rear side surfaces of the flange 35, and movement of the shaft 2 in the axial direction is restricted. Therefore, since the shaft 2 is securely held by the bearing metals 3 and 4 through the pressure oil in a state where the shaft 2 is held at the predetermined axial position, the shaft 2 may not come into contact with the bearing metals 3 and 4. Absent.

If there is no communication passage 13 that connects the first pocket 11 and the second pocket 12 to each other, a certain degree of static rigidity can be obtained by the static rigidity pressure fluid supplied to the first pocket 11. Since the pressure change in the first pocket 11 does not sensitively react to the change in the gaps 5 and 6 described above,
Sufficient static rigidity cannot be obtained.

Further, in addition to the second pocket 12 for securing the static pressure, the dynamic pressure land 2 having predetermined gaps 5, 6 for securing the dynamic pressure is provided.
Since the first pocket 11 for ensuring the static rigidity is also provided inside 1, the area for ensuring the static rigidity and the area for ensuring the dynamic rigidity can be made substantially the same. Therefore, the areas are separated from each other. The shaft 2 can be supported more stably than when it is installed.

Further, when the shaft 2 is rotated at a high speed, a signal from the rotation sensor 27 of the shaft 2 is output to the control device 26, and the set value set by the setter 28 is compared with the detected value to detect the detected value. If the value exceeds the set value, the control device 2
An opening operation signal is output from 6 to the on-off valve 25. Therefore, the opening / closing valve 25 is opened and a large amount of lubricating oil is supplied from the hydraulic pump 18 to the supply port 23 through the pipe line 24. This hydraulic pressure is supplied to the plurality of conduction paths 22 through the annular groove 1a, is supplied to the second static pressure pocket 12 and is also supplied to the first static pressure pocket 11 through the communication path 13, and the first static pressure pocket is supplied. 11 is supplied to the dynamic pressure land 21. Therefore, when the shaft 2 is rotated at a high speed, the shaft 2 is stably rotated at a high speed in a state of being securely held by the high-pressure lubricating oil in the dynamic pressure land 21 with a predetermined rigidity, and a large amount of lubrication is supplied. Oil
It is possible to suppress the heat generation in the gap caused by the high speed rotation.

The oil flowing into the annular groove 31 through the gap 5 behind the second static pressure pocket 12 and the oil flowing out of the dynamic pressure land 21 into the annular groove 31 are piped through the discharge passage 32 and the discharge port 33. It is led from the path 34 to the oil tank 20.

Next, another embodiment of the present invention will be described with reference to FIG. In this embodiment, a switching valve 41 is provided for the pipe 24 discharged from the hydraulic pump 18, and a parallel circuit having a fixed throttle 42 is provided from the position of the switching valve 41. When the shaft 2 is stationary or rotates at a low speed, by supplying lubricating oil from the switching valve 41 to the throttle 42 side, the first and second
The static pressure oil is supplied to the static pressure pockets 11 and 12. or,
When the shaft 2 reaches a rotation speed above a predetermined value, the switching valve 4
1 to switch the dynamic pressure oil from the hydraulic pump 18 to the conduction path 2
2. The first static pressure pocket 11 is supplied via the communication passage 13, and the lubricating oil is supplied from the pocket 11 to the dynamic pressure land 21.

The present invention is not limited to the above embodiment, but can be embodied as follows, for example. (1) The bearing metals 3 and 4 are divided into a plurality of first and second parts.
The pockets 11 and 12 of the above are formed by piping having a communication passage 13.

(2) To make at least one of the first and second pockets 11 and 12 plural. (3) In the above embodiment, the first pocket 11 is used as the housing 1
Inside, the second pocket 12 was placed outside, but vice versa.

(4) In the above embodiment, the journal bearing is embodied, but in place of this, it is embodied as a slide body supporting structure for supporting a movable table on a fixed bed so as to be capable of horizontal reciprocating movement. .

[0029]

As described above in detail, according to the present invention, the static rigidity can be maintained when the sliding body is stationary or at a low speed, and when the sliding body is at a high speed, the sliding body is driven by the dynamic pressure. The rigidity can be ensured and the effect of suppressing heat generation is obtained.

[Brief description of drawings]

FIG. 1 is an enlarged cross-sectional view of a main part showing an embodiment in which the present invention is embodied in a journal bearing.

FIG. 2 is a sectional view showing the entire journal bearing.

3 is a cross-sectional view taken along the line AA of FIG.

FIG. 4 is a sectional view taken along line BB in FIG.

5 is a cross-sectional view taken along line CC of FIG.

FIG. 6 is a partial sectional view showing another embodiment of the present invention.

[Explanation of symbols]

1 ... Housing, 2 ... Shaft as movable support, 3, 4 ...
Bearing metal as a fixed support 5, 6, ... Gap, 11,
12 ... First and second static pressure pockets, 13 ... Communication passage, 1
4, 22 ... Conducting path, 15, 23 ... Supply port, 16 ... Restrictor, 18 Hydraulic pump as pressure fluid supply source, 21 ...
Dynamic pressure land, 25 ... open / close valve, 26 ... control device.

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[Procedure amendment]

[Submission date] February 24, 1993

[Procedure Amendment 1]

[Document name to be corrected] Drawing

[Name of item to be corrected] Figure 2

[Correction method] Change

[Correction content]

[Fig. 2]

Claims (1)

[Claims] 1. A dynamic pressure land for supporting a movable support against a sliding surface of a fixed support, and having a predetermined gap between them for securing a dynamic pressure to which a pressure fluid is applied from a pressure fluid supply source. And a first pocket and a second pocket for securing static pressure rigidity to which a pressure fluid is applied from the pressure fluid supply source are provided on the sliding surface of the fixed support, and the first pocket and the pressure fluid supply source are provided. A support structure for the sliding body, in which a throttle is provided between the first and second pockets, and the first pocket is disposed inside the dynamic pressure land, and the first pocket and the second pocket are communicated by a communication path.