JP2004116580A - Bearing device and machining device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a bearing device (machining device) equipped with a cooling device for controlling a temperature of liquid for a bearing whereby the cost regarding the cooling device can be reduced. <P>SOLUTION: This bearing device is equipped with a shaft member and a bearing member, and bears the shaft member by the bearing member through the liquid for the bearing. The bearing device is provided with a motor for rotating the shaft member, a first cooling means for cooling the liquid for the bearing and varying the operation condition in accordance with a temperature of the liquid for the bearing so as to be used, and a second cooling means for cooling the liquid for the bearing and varying the operation condition in accordance with a number of revolutions of the motor so as to be used. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a bearing device and a machine tool.
[0002]
[Prior art]
A "bearing structure" in which a bearing member bears a shaft member is employed in many machines. For example, many machine tools used for grinding of metals, semiconductors, and the like (double-side grinding of semiconductor wafers, etc.) include a “bearing structure” in which a bearing member bears a shaft member that is a spindle.
[0003]
Fluid bearings, such as a liquid bearing that uses a bearing liquid as a medium and an air bearing that uses a bearing air as a medium, are known as specific modes when the bearing member bears the shaft member. For example, in many machine tools used for grinding of metals, semiconductors, and the like, a bearing member (a liquid bearing) is used as a bearing member for a shaft member, which is a spindle, using a bearing liquid as a medium. Liquid bearings are used instead of air bearings. Liquid bearings are superior to air bearings in terms of damping characteristics, so liquid bearings are more suitable than air bearings for high-precision machining. Because it is.
[0004]
[Patent Document 1]
JP-A-11-33906 [Patent Document 2]
JP-A-2001-59521.
[0005]
[Problems to be solved by the invention]
As described above, most machine tools used for grinding metal, semiconductors, and the like employ liquid bearings for the purpose of high-precision machining. In order to achieve high-precision machining, the temperature of the bearing liquid must be strictly controlled.
[0006]
In machine tools that employ liquid bearings for high-precision machining, the temperature of the bearing liquid is usually controlled within a temperature range of about ± 0.1 ° C. to ± 0.5 ° C. depending on the machining precision. . For example, in a spindle having a main shaft protruding 200 mm from the thrust portion as shown in FIG. 1, when the main shaft is formed of iron, when the temperature is controlled within a temperature range of about ± 0.1 ° C., the axial direction is ± 0 °. When an error of about 2 μm occurs and the temperature is controlled within a temperature range of about ± 0.5 ° C., an error of about ± 1.0 μm occurs in the axial direction.
[0007]
The temperature of the bearing liquid is controlled using a cooling device, a heating device, or the like. For example, a temperature sensor for detecting the temperature of the bearing liquid is provided, and the operating state of each cooling device and each heating device is changed according to the temperature detected by the temperature sensor to manage the temperature of the bearing liquid. Such a temperature sensor may be provided, for example, in a tank containing a bearing liquid, or if a time lag from a temperature difference between the inside and outside of the tank or a temperature change to a temperature detection is taken into consideration, Japanese Patent Laid-Open No. 2001-59521. As in the invention described in Japanese Patent Application Laid-Open Publication No. H10-205, a return portion of the circulation path for the bearing liquid may be provided.
[0008]
Here, the amount of heat generated by the liquid bearing will be evaluated. The relational expression (1) in FIG. 2 is a calculation expression for the friction torque T relating to the thrust bearing, and the relational expression (2) in FIG. Since the heat source of the heat generated by the liquid bearing is mainly power N, the amount of heat generated by the liquid bearing can be evaluated by the power N. According to the relational expression (2) in FIG. 2, N is proportional to the fourth power of D. This means that the calorific value increases dramatically with the enlargement of the spindle. Although the relational expression of FIG. 2 is calculated by considering only the thrust portion of the thrust portion and the radial portion, the calculation is also performed by considering the radial portion.
[0009]
The increase in the amount of heat generated by the increase in the size of the spindle can be dealt with by increasing the size of the cooling device for managing the temperature of the bearing liquid. However, as described above, the amount of heat generated dramatically increases with the increase in the size of the spindle, so that the cooling device becomes larger than the rate of increase in the size of the spindle. This results in increased costs for the cooling device.
[0010]
Therefore, an object of the present invention is to suppress the cost of a cooling device for a bearing device (machine tool) including a cooling device for temperature management of a bearing liquid.
[0011]
[Means for Solving the Problems]
The invention (bearing device) according to claim 1 includes a shaft member and a bearing member, and in a bearing device in which the bearing member bears the shaft member through a bearing liquid, a motor that rotates the shaft member. A cooling means for cooling the bearing liquid, a first cooling means being a cooling means for changing an operation state according to the temperature of the bearing liquid, and cooling the bearing liquid. And a second cooling unit which is a cooling unit for changing an operation state according to the number of rotations of the motor for use.
[0012]
The invention (bearing device) according to claim 2 is the same as the invention (bearing device) according to claim 1, further comprising a sensor for detecting the temperature of the bearing liquid, and wherein the first cooling unit is detected by the sensor. The operation state is automatically controlled in accordance with the set temperature.
[0013]
The invention (bearing device) according to claim 3 is the same as the invention (bearing device) according to claim 1, wherein the operating state of the second cooling means is automatically controlled according to the rotation speed of the motor.
[0014]
An invention (bearing device) according to a fourth aspect is the invention (bearing device) according to the third aspect, further comprising a controller that sets the number of revolutions of the motor, and wherein the second cooling unit is set by the controller. The operation state is automatically controlled according to the rotation speed.
[0015]
An invention (bearing device) according to a fifth aspect is the invention (bearing device) according to the third aspect, further comprising a sensor for detecting the number of revolutions of the motor, and wherein the second cooling unit is detected by the sensor. The operation state is automatically controlled according to the rotation speed.
[0016]
The invention (bearing device) according to claim 6 relates to the invention (bearing device) according to claim 1, wherein the second cooling unit can manually switch an operation state according to the number of rotations of the motor. .
[0017]
An invention (bearing device) according to a seventh aspect is the invention (bearing device) according to the sixth aspect, further comprising a controller that sets the number of revolutions of the motor, and wherein the second cooling unit is set by the controller. The operating state can be manually switched according to the rotation speed.
[0018]
The invention (bearing device) according to claim 8 is the same as the invention (bearing device) according to any one of claims 1 to 7, wherein the second cooling means operates in accordance with the rotation speed of the motor. Is a cooling means for changing the ON / OFF state for use.
[0019]
The invention (bearing device) according to claim 9 is a bearing device comprising a shaft member and a bearing member, wherein the bearing member bears the shaft member through a bearing liquid, and the motor rotates the shaft member. A cooling means for cooling the bearing liquid, a first cooling means being a cooling means for changing an operation state according to the temperature of the bearing liquid, and cooling the bearing liquid. And a second cooling unit which is a cooling unit for changing an operation state and using the same in order to cancel thermal energy generated by the power of the motor.
[0020]
According to a tenth aspect of the present invention, there is provided a machine tool including the bearing device according to any one of the first to ninth aspects, wherein the shaft member is a spindle.
[0021]
According to an eleventh aspect of the present invention, there is provided a machining apparatus including the bearing device according to any one of the first to ninth aspects, wherein the shaft member is a spindle for grinding.
[0022]
According to a twelfth aspect of the present invention, there is provided a machining apparatus including the bearing device according to any one of the first to ninth aspects, wherein the shaft member is a spindle for double-head grinding.
[0023]
In the invention (bearing device or machine tool) according to any one of claims 1 to 12, the cooling device for managing the temperature of the bearing liquid is a relatively precise but small and expensive first cooling means. Thus, it is possible to suppress the cost of the cooling device for controlling the temperature of the bearing liquid by using a relatively inexpensive second cooling means which is relatively inexpensive and large.
[0024]
BEST MODE FOR CARRYING OUT THE INVENTION
An embodiment of the present invention will be described.
[0025]
FIG. 3 shows a bearing device 301 according to an embodiment of the present invention. 3 includes a shaft member 101, a bearing member 102, a motor 103, a liquid supply pump 201, a temperature sensor 202, a cooling head 203, a precision cooling device 204, and a large cooling device 205. Prepare.
[0026]
The bearing device 301 is a device in which the bearing member 102 carries the bearing (liquid bearing) of the shaft member 101 through the bearing liquid 302. As a use of the bearing device 301, for example, a machine tool having the bearing device 301 mounted thereon and the shaft member 101 serving as a spindle can be considered. Such a machining apparatus can be used for grinding of a metal, a semiconductor, or the like for the purpose of high-precision machining (double-side grinding of a semiconductor wafer, etc.). The spindle is used as a spindle for grinding and the like (for double-sided grinding) and the machine is used as a machine for grinding and the like (for double-sided grinding).
[0027]
The shaft member 101 has a shaft tip 104. When the shaft member 101 is a spindle, the shaft tip 104 becomes the main shaft. The bearing member 102 has a bearing metal 105 and a liquid supply port 106. The bearing liquid 302 is supplied between the shaft member 101 and the bearing member 102 through the liquid supply port 106. The motor 103 rotates the shaft member 101. The motor 103 may rotate the shaft member 101 directly, or may rotate the shaft member 101 indirectly via a belt member or the like.
[0028]
The liquid supply pump 201 circulates the bearing liquid 302 along a circulation path as shown in FIG. The temperature sensor 202 detects the temperature of the bearing liquid 302 in the middle of the circulation path. Here, the precision cooling device 204 is a relatively precise but small and expensive cooling device which is composed of one cooling device, and cools the bearing liquid 302 in the middle of the circulation path. Here, the large-sized cooling device 205 is composed of two coolers, and is a relatively inexpensive large-sized and inexpensive cooling device, and cools the bearing liquid 302 in the middle of the circulation path. The precision cooling device 204 is a cooling device for changing the operation state according to the temperature of the bearing liquid 302 and using it. The large cooling device 205 changes the operation state according to the rotation speed of the motor 103. A cooling device for use.
[0029]
Hereinafter, the operation of the bearing device 301 will be described using a machine tool as an example.
[0030]
FIG. 4 is a graph related to the power of the motor 103. The power 1 is a graph when the shaft member 101 according to the liquid bearing (hydrostatic bearing) is rotated at 4000 rpm, and the power 2 is the shaft member 101 according to the liquid bearing (hydrostatic bearing) is rotated at 6000 rpm. It is a graph at the time. An increment of about 1 kW that appears periodically is the power required for processing. When a spindle as shown in FIG. 1 is used, 5 kW is required as an offset at 4000 rpm, and 10 kW is required as an offset at 6000 rpm. The value of the offset can be obtained almost at the design stage, and becomes almost the same value when the rotation speed of the motor 103 is determined.
[0031]
The power of the motor 103 is converted into heat energy, a part of which is consumed for raising the temperature of the shaft member 101 and the bearing member 102, and most of it is consumed for raising the temperature of the bearing liquid 302. You. Therefore, the temperature of the bearing liquid 302 is managed using the precision cooling device 204, the large cooling device 205, and the like.
[0032]
The operation at the time of starting the machine tool will be described.
[0033]
When the power of the machine is turned on, the operation of the liquid supply pump 201 is started, and the bearing liquid 302 is supplied between the shaft member 101 and the bearing member 102. The bearing member 102 carries out the bearing (liquid bearing) of the shaft member 101 with the bearing liquid 302 as a medium.
[0034]
At the same time or before or after this, the operation of the precision cooling device 204 is also started. The precision cooling device 204 cools the bearing liquid 302 returned along the circulation path through the cooling head 203. Here, the temperature of the bearing liquid 302 returned along the circulation path is detected by the temperature sensor 202. The operation state of the precision cooling device 204 is automatically controlled according to the temperature detected by the temperature sensor 202. Thus, the temperature of the bearing liquid 302 is managed.
[0035]
The temperature of the bearing liquid 302 is controlled within a temperature range of about ± 0.1 ° C. to ± 0.5 ° C. with respect to the set temperature. The capacity of the precision cooling device 204 needs to be large enough to control the temperature rise caused by the processing power. For example, a power as shown in FIG. 4 requires a processing power of about 1 kW. Therefore, a capacity of about 2 kW, which is twice the assumed processing power, is required.
[0036]
The operation of the machining device during machining will be described.
[0037]
When performing machining using a machine tool, the spindle is rotated by rotating the motor 103. Here, in order to cancel the heat energy newly generated by the power of the motor 103, the operation of the large-sized cooling device 205 as well as the precise cooling device 204 is started. The bearing liquid 302 returned along the circulation path is first cooled by the large-sized cooling device 205 and then cooled by the precision cooling device 204. Thus, the temperature of the bearing liquid 302 is managed. In this way, by using the relatively inexpensive large-sized cooling device 205 which is relatively inexpensive but not to increase the size of the relatively accurate but expensive precision cooling device 204, it is possible to control the temperature of the bearing liquid 302. Cost of the cooling device can be suppressed. It is considered that such temperature management is particularly suitable for a machine tool such as a "machine tool for double-head grinding" in which there are two main spindles and the amount of heat generation during operation is small.
[0038]
When performing machining using a machine tool, the rotation speed of the motor 103 (the rotation speed of the spindle) is set by a controller. The power of the motor 103 required to achieve a desired rotation speed is constant and can be obtained by calculation or measurement. Therefore, in order to cancel the heat energy newly generated by the power of the motor 103, the operation state of the large-sized cooling device 205 may be changed according to the rotation speed of the motor 103. Therefore, the operation state of the large-sized cooling device 205 is automatically controlled according to the rotation speed set by the controller. Alternatively, the operation state of the large-sized cooling device 205 may be manually switched according to the rotation speed set by the controller. Alternatively, a rotation speed sensor for detecting the rotation speed of the motor 103 (the rotation speed of the spindle) is provided, and the operation state of the large-sized cooling device 205 is automatically controlled according to the rotation speed detected by the rotation speed sensor. You may.
[0039]
Note that an ON / OFF change can be considered as a change mode of the operation state of the large-sized cooling device 205. In this case, the large-sized cooling device 205 may be a device capable of only the ON / OFF change or a device other than the ON / OFF change, but from the viewpoint of suppressing the cost of the cooling device for temperature management of the bearing liquid 302. Therefore, it can be said that the former is superior.
[0040]
In particular, as shown in FIG. 3, when the large-sized cooling device 205 includes a plurality of cooling devices (two in FIG. 3), ON / OFF changes for each cooling device are conceivable. This is because, by changing the combination of the cooler to be turned on and the cooler to be turned off, variations in the operation state of the large-sized cooling device 205 become rich. In this case, each refrigerator may be capable of performing only the ON / OFF change or may be capable of performing other than the ON / OFF change, but from the viewpoint of suppressing the cost related to the cooling device for temperature management of the bearing liquid 302. Can be said to be superior to the former.
[0041]
Although the bearing device according to the hydrostatic bearing has been described above, the bearing device according to the dynamic pressure bearing may be used.
[0042]
The cooling system for cooling the bearing liquid has been described above, but may be a cooling system for cooling other liquids. For example, a system for cooling a cutting fluid whose calorific value is known from the beginning may be used.
[0043]
【The invention's effect】
As described above, the present invention makes it possible to suppress the cost of the cooling device with respect to the bearing device (machining device) including the cooling device for temperature management of the bearing liquid.
[Brief description of the drawings]
FIG. 1 shows a spindle according to a machine tool.
FIG. 2 is a relational expression for evaluating the amount of heat generated by the liquid bearing.
FIG. 3 shows a bearing device according to an embodiment of the present invention.
FIG. 4 is a graph related to the power of a motor.
[Explanation of symbols]
101 Shaft member 102 Bearing member 103 Motor 104 Shaft tip 105 Bearing metal 106 Liquid supply port 201 Liquid supply pump 202 Temperature sensor 203 Cooling head 204 Precision cooling device 205 Large cooling device 301 Bearing device 302 Bearing liquid

Claims (12)

In a bearing device including a shaft member and a bearing member, wherein the bearing member bears the shaft member through a bearing liquid, a motor for rotating the shaft member and cooling means for cooling the bearing liquid. A first cooling unit that is a cooling unit for changing an operation state according to a temperature of the bearing liquid, and a cooling unit that cools the bearing liquid. A bearing device comprising: a second cooling unit that is a cooling unit for changing an operation state according to use. The bearing device according to claim 1, further comprising a sensor for detecting a temperature of the bearing liquid, wherein an operation state of the first cooling unit is automatically controlled in accordance with the temperature detected by the sensor. . The bearing device according to claim 1, wherein an operation state of the second cooling unit is automatically controlled in accordance with a rotation speed of the motor. 4. The bearing device according to claim 3, further comprising a controller that sets a rotation speed of the motor, wherein the second cooling unit automatically controls an operation state according to the rotation speed set by the controller. 5. . 4. The bearing device according to claim 3, further comprising a sensor that detects a rotation speed of the motor, wherein the second cooling unit automatically controls an operation state according to the rotation speed detected by the sensor. 5. . The bearing device according to claim 1, wherein the second cooling unit can manually switch an operation state according to a rotation speed of the motor. The bearing according to claim 6, further comprising a controller that sets a rotation speed of the motor, wherein the second cooling unit can manually switch an operation state according to the rotation speed set by the controller. apparatus. The said 2nd cooling means is a cooling means for changing an operation state ON / OFF according to the rotation speed of the said motor, and using it, The Claim 1 characterized by the above-mentioned. Bearing device. In a bearing device comprising a shaft member and a bearing member, wherein the bearing member bears the shaft member with a bearing liquid as a medium, a motor for rotating the shaft member and cooling means for cooling the bearing liquid. A first cooling unit that is a cooling unit for changing an operation state according to a temperature of the bearing liquid, and a cooling unit that cools the bearing liquid, wherein the first cooling unit is generated by power of the motor. A second cooling means which is a cooling means for changing the operating state and using the same in order to cancel the heat energy generated. A machining apparatus comprising the bearing device according to claim 1, wherein the shaft member is a spindle. A machining device comprising the bearing device according to claim 1, wherein the shaft member is a spindle for grinding. A machine tool comprising the bearing device according to claim 1, wherein the shaft member is a spindle for double-head grinding.

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