JP2002139038A - Temperature control method of air static pressure bearing and air static pressure bearing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To maintain an air static pressure bearing to a predetermined temperature by a more simple constitution. SOLUTION: A temperature of the air static pressure bearing formed by radial and thrust bearing rings 14, 15, 16, 17 having a porous body 18 is detected by a temperature sensor 23. A difference of this detection temperature and a set temperature previously set in a setter 26 is determined by a comparator 25. Based on the difference signal from the comparator 25, the temperature of the air static pressure bearing is maintained to the set temperature by controlling a temperature of an air for the air static pressure bearing fed from an air feed source 21 for air static pressure bearing to the porous body 18 by a compensation circuit 28 so as to approach this difference signal to zero.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an aerostatic bearing, and more particularly to a method and a device for controlling the temperature of an aerostatic bearing for suppressing a change in the temperature of the bearing due to heat generated during operation.

[0002]

2. Description of the Related Art Hydrostatic bearings are used in precision machines and equipment. Since the static air bearing generates less heat and has a cooling action itself, conventionally, the temperature control of the static air bearing itself has not been given much importance.

[0003] Generally, precision machines and equipment that require higher precision are installed in a constant temperature room, and the entire precision machines and equipment are maintained at a predetermined temperature. It has been proposed to suppress the thermal displacement by supplying air at a predetermined constant temperature to an air static pressure bearing of a precision machine / equipment installed in a constant temperature chamber (Japanese Patent Publication No. 7-55440).

[0004]

In recent years, porous bodies such as carbon, ceramics, and metals have been used for aerostatic bearings. An aerostatic bearing using this porous body, that is, a porous aerostatic bearing, has a very small bearing gap of 5 to 8 μm, generates heat, and particularly in an aerostatic bearing that supports a high-speed rotating shaft, Heat generation in the bearing portion cannot be ignored.

Japanese Patent Application Laid-Open No. 10-205538 discloses an invention for coping with heat generated by a porous air static pressure bearing. In this invention, a cooling water passage is provided around the porous body to keep the temperature of the bearing constant, but the structure is complicated.

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for controlling the temperature of an aerostatic bearing and a device for aerostatic bearing which can maintain the aerostatic bearing at a predetermined temperature with a simpler structure.

[0007]

According to the present invention, there is provided a method for controlling a temperature of an aerostatic bearing according to the present invention, comprising detecting a temperature of the aerostatic bearing, and detecting the detected temperature and a preset temperature. The temperature of the air for the hydrostatic bearing supplied to the hydrostatic bearing is controlled so that the difference approaches zero based on the difference, and the temperature of the hydrostatic bearing is set to the set temperature. It is characterized by keeping.

According to this method, the bearing temperature can be maintained at a predetermined value simply by controlling the temperature of the air for the hydrostatic bearing, and the structure of the bearing itself is not complicated.

The present invention is effective when applied to a porous aerostatic bearing having a small bearing gap as described above, and if a metal porous body is used, the present invention is applicable to a porous body. Since the thermal conductivity is high, the control of the bearing temperature is performed more effectively. In order to more effectively control the bearing temperature, it is preferable that the bearing temperature is detected by detecting the temperature of the heat generating portion accompanying the operation of the aerostatic bearing.

[0010] In order to achieve the above object, an aerostatic bearing device according to the present invention comprises:
An air temperature controller provided in a supply unit of the air static pressure bearing air supplied to the air static pressure bearing constituting the air static pressure bearing device for changing the temperature of the air; and A temperature sensor for detecting a temperature, and adjusting the temperature of the air by the air temperature controller so that a difference between a temperature of the air static pressure bearing detected by the temperature sensor and a preset set temperature approaches zero. And a control unit for performing the temperature control method of the aerostatic bearing.

As described above, the aerostatic bearing is preferably a porous aerostatic bearing, and this aerostatic bearing is made of a metal porous body. It is further preferable that the temperature sensor is installed in a heat-generating portion associated with the operation of the aerostatic bearing.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIG. Reference numeral 10 denotes a bearing housing, which is a main housing 11 located on the right side in FIG. 1, a rear housing 12 also located on the left side in FIG. 1, and an intermediate housing (intermediate ring) located therebetween.
13 In the main housing 11, radial bearing rings 14, 15 are mounted in series. Thrust bearing rings 16 and 17 are attached to the surfaces of the main housing 11 and the rear housing 12 that face each other.

Numeral 30 denotes a rotary shaft, which has a collar 31 near the left end in FIG. 1. The right and left end faces of the collar 31 are received by the thrust bearing rings 16 and 17 and are also viewed from the collar 22. At 1 the right outer peripheral surface is received by the radial bearing rings 14,15. These radial and thrust bearing rings 14, 15, 16, 17
Is provided with a porous body 18 forming a porous aerostatic bearing.

An air supply path 19 provided in the bearing housing 10 is connected to the back surface of each porous body 18, and the air supply path 19 is connected to an air supply source 21 for an aerostatic bearing via an air temperature controller 20. It is connected to the. Air temperature controller 20
A method of adjusting the temperature of the air for hydrostatic bearing supplied to each porous body 18 to a predetermined temperature by a heating and cooling means using water and a heater, or a method of controlling the temperature of the air previously controlled to a predetermined temperature. A method is used in which the mixing ratio of the two types of air is adjusted and the temperature of the air for hydrostatic bearing supplied to each porous body 18 is adjusted to a predetermined temperature. 22 is an air discharge path.

A built-in type servo motor 32 is incorporated at the left end of the rotary shaft 30 in FIG. 1, and a rotary encoder 33 is mounted so that the rotary shaft 30 can be rotated at a desired speed by a desired amount. ing.

A temperature sensor 23 is mounted near the surface of the thrust bearing ring 16 facing the flange 31. The temperature sensor 23 is connected to the comparator 2 via an amplifier 24.
5 is connected. Reference numeral 26 denotes a setting unit.
Calculates the difference between the temperature detected by the temperature sensor 23 and the set temperature preset in the setter 26. The difference signal from the comparator 25 is amplified by the amplifier 27, the air temperature controller 20 is operated by the compensation circuit 28 using PID control or the like, and the difference signal is supplied to each porous body 18 so as to approach zero. It is configured to control the temperature of the air for the aerostatic bearing.

Next, the operation of the present apparatus will be described. When the rotating shaft 30 is stopped, there is no heat generated between the rotating shaft 30 and the radial and thrust bearing rings 14, 15, 16, 17;
The temperature in the vicinity of the surface opposite to the set temperature is substantially equal to the set temperature preset in the setter 26.

Therefore, in this state, the temperature detected by the temperature sensor 23 is almost equal to the temperature set by the setter 26, the difference signal from the comparator 25 is almost zero, and the compensation circuit 28
The temperature of the air supplied to each porous body 18 from the air supply source 21 for the aerostatic bearing is set by the air temperature controller 20 to the setting device 2.
The temperature is controlled to be substantially equal to the set temperature of 6.

When the rotating shaft 30 rotates at a particularly high speed, as described above, the aerostatic bearing, particularly the porous aerostatic bearing,
Since the bearing gap is as very small as 5 to 8 μm, the rotating shaft 30 and the radial and thrust bearing rings 14, 15, 1
Heat is generated between 6, and 17. The temperature rise of the radial and thrust bearing rings 14, 15, 16, 17 and the rotating shaft 30 due to this heat is detected by the temperature sensor 23, and the difference between the detected temperature and the set temperature set in the setter 26 is compared. Determined by the vessel 25.

The difference signal obtained by the comparator 25 is amplified by an amplifier 27 and supplied to a compensation circuit 28.
The compensation circuit 28 operates the air temperature controller 20 so as to lower the temperature of the air supplied to each porous body 18 by a predetermined amount from the set temperature according to the magnitude of the difference signal. As described above, by lowering the temperature of the air supplied to each porous body 18 by a predetermined amount from the set temperature, the radial and thrust bearing rings 14, 15, 16, 17 including each porous body 18 are provided.
In addition, the temperature rise of the rotating shaft 30 is suppressed, and these temperatures are substantially maintained at the set temperature.

In order to enhance the temperature control effect of the radial and thrust bearing rings 14, 15, 16, 17 including each porous body 18 by adjusting the temperature of the air supplied to each porous body 18, Preferably, the porous body 18 has a high thermal conductivity, and in this sense, the porous body 18 is preferably a metal porous body such as bronze.

In the above-described embodiment, the peripheral speed of the outer periphery of the collar 31 of the rotating shaft 30 is the highest, and the temperature rise near the outer periphery of the thrust bearing rings 16 and 17 facing this portion appears more greatly. An example was shown in which the temperature sensor 23 was installed near the outer periphery of the bearing ring 16 so as to catch the temperature rise as soon as possible, but the temperature sensor 23 was installed on the radial bearing rings 14 and 15. The location of the temperature sensor 23 can be changed in various ways, and the temperature sensors 23 are provided at a plurality of locations in order to average the temperature control of the radial and thrust bearing rings 14, 15, 16, and 17. The average value of these temperature sensors 23 may be given to the comparator 25.

Furthermore, if more precise control is required, the radial and thrust bearing rings 14, 15, 1
It is also possible to detect the temperatures of 6 and 17 and supply air of which temperature is separately adjusted to each of them.

[0024]

As described above, according to the present invention, the temperature of the aerostatic bearing is detected by detecting the temperature of the aerostatic bearing and adjusting the temperature of the air supplied to the aerostatic bearing based on the detected temperature. Since the temperature is maintained at the set temperature, an effect is obtained that the aerostatic bearing can be maintained at a predetermined temperature with a simple configuration without complicating the structure of the bearing portion. INDUSTRIAL APPLICABILITY The present invention is applied to a porous aerostatic bearing in which the bearing gap is small and heat generation becomes a problem, and is more sensitive to the temperature of the air for aerostatic bearings. The effect is large in a porous air static pressure bearing using a porous body. Further, if the detection of the bearing temperature is performed by the heat generating portion associated with the operation of the aerostatic bearing, the heat generation can be captured early and the change in the bearing temperature can be suppressed more accurately.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing an embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Bearing housing 11 Main housing 12 Rear housing 13 Intermediate housing (intermediate ring) 14, 15 Radial bearing ring 16, 17 Thrust bearing ring 18 Porous body 19 Air supply path 20 Air temperature controller 21 Air supply source for aerostatic bearing Reference Signs List 22 air exhaust path 23 temperature sensor 24, 27 amplifier 25 comparator 26 setter 28 compensation circuit 30 rotation axis 31 collar 32 servo motor 33 rotary encoder

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 3C048 BB14 BB20 3J102 AA02 BA03 BA19 CA07 CA33 EA02 EA06 EA18 EB05 EB16 FA01 FA08 GA01 GA13

Claims (8)

[Claims] 1. A method for controlling the temperature of an aerostatic bearing, comprising:
A temperature of the aerostatic bearing is detected, a difference between the detected temperature and a preset set temperature is obtained, and based on the difference, the aerostatic pressure supplied to the aerostatic bearing is adjusted to approach zero. A method for controlling the temperature of an aerostatic bearing, comprising controlling the temperature of the air for a pressure bearing to maintain the temperature of the aerostatic bearing at the set temperature. 2. The temperature control method for an aerostatic bearing according to claim 1, wherein said aerostatic bearing is a porous aerostatic bearing. 3. The method of controlling a temperature of an aerostatic bearing according to claim 2, wherein said porous aerostatic bearing uses a metal porous body. 4. The method of controlling a temperature of an aerostatic bearing according to claim 1, wherein the temperature of the bearing is detected by detecting a temperature of a heat generating portion associated with an operation of the aerostatic bearing. . 5. An air static pressure bearing device, wherein the air static pressure bearing device is provided in a supply section of an air static pressure bearing air supplied to an air static pressure bearing constituting the air static pressure bearing device, for changing a temperature of the air. An air temperature controller, a temperature sensor that detects the temperature of the static air bearing, and a difference between the temperature of the static air bearing detected by the temperature sensor and a preset set temperature approaches zero. And a control unit for controlling the temperature of the air by the air temperature controller. 6. An aerostatic bearing device according to claim 5, wherein said aerostatic bearing is a porous aerostatic bearing. 7. The aerostatic bearing device according to claim 6, wherein said porous aerostatic bearing uses a metal porous body. 8. The aerostatic bearing device according to claim 5, wherein the temperature sensor is provided in a heat generating portion accompanying the operation of the aerostatic bearing.