JPH11270554A - Method and device for preventing bearing from providing poor rotation to heated shaft - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a bearing from making proof rotation due to a decrease of a rolling gap by heating the outer ring of a rolling bearing coupled with a heated shaft, and compensating the temperature difference between the outer ring and the inner ring of the bearing. SOLUTION: An electric heater 14 is installed on the outside of the outer ring 3 of a bearing to heat the outer ring 3. The temperature of a shaft 1 is measured by a sensor 10 directly near the bearing, the temperature of the outer ring 3 is measured by a sensor 11, both temperatures are inputted to a control device 12 respectively, and the control device 12 adjusts a power supply 13 to make the difference zero and controls the heating quantity of the electric heater to make the temperature of the outer ring 3 nearly equal to the temperature of the shaft 1. The outer ring 3 and the shaft 1 can be kept nearly equal in temperature from a cold operation to a hot operation by this device, the thermal expansion quantities of the outer ring 3 and the inner ring 2 of the bearing are made nearly equal, and a defective bearing rotation due to a decrease of a rolling gap does not occur. The rolling gap during the cold operation is not required to be increased, thereby the occurrence of the abnormal vibration of the bearing caused by the unbalance of a shaft system can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and a device for preventing a bearing from rotating poorly on a shaft to be heated, and more particularly to a rolling bearing in which a rotating shaft is heated like a fan in a furnace.

[0002]

2. Description of the Related Art FIG. 4 shows an example of a rotating shaft which is supported by a rolling bearing and whose shaft end is heated. In FIG. 4, one end of the shaft 1 is in a furnace and is heated by a heating source. At this time, since the bearing inner ring 2 is in contact with the shaft 1, it is heated by contact heat transfer from the shaft. On the other hand, since the bearing outer ring 3 is only in point contact with the bearing inner ring 2 via the rolling elements 4, heat from the shaft 1 is hardly transmitted. For this reason, the temperature of the inner ring 2 becomes higher than the temperature of the outer ring 3, and the inner ring 2 expands more thermally than the outer ring 3, so that the rolling gap of the rolling element 4 is reduced and the required power for rotation is increased. Causes rotation failure.

In order to solve this problem, means for selecting a bearing having a large rolling clearance is generally used. However, for example, in the case of a bearing used to support an in-furnace fan, if a bearing having a large rolling gap is selected in order to obtain a required rolling gap between hot, the rolling gap becomes large during a cold operation immediately after the start of line operation. The bearing may be abnormally vibrated due to shaft whirling due to imbalance of the fan rotating portion.

[0004]

As described above, in a rolling bearing that supports a rotating shaft that is being heated, the inner ring temperature is higher than the outer ring temperature, so that the amount of thermal expansion of the inner ring becomes larger than that of the outer ring. Insufficient dynamic clearance causes poor rotation. On the other hand, if a bearing having a large rolling clearance is selected, there is a problem that abnormal vibration occurs in the bearing during the cold operation immediately after the start of the line operation.

It is an object of the present invention to provide a method and an apparatus for preventing a bearing rotation failure to solve the above problems.

[0006]

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and heats an outer ring of a rolling bearing fitted on a shaft to be heated to reduce a temperature difference between the outer ring and the inner ring of the bearing. This is a method for preventing bearing rotation failure of a heated shaft, which is characterized in that compensation is performed. To compensate for the temperature difference means to control the temperature of the outer ring and the inner ring of the rolling bearing that supports the rotating shaft to be heated to be substantially the same.

[0007] The apparatus of the present invention which can suitably carry out the above method of the present invention comprises a heating means for heating the outer ring of the rolling bearing, a temperature measuring means for measuring the temperatures of the shaft and the outer ring in the vicinity of the bearing, respectively, A control device for inputting a measured temperature of the means and controlling a heating amount of the heating means so that the temperature difference becomes zero. Here, the heating means may be any means as long as the heating amount can be adjusted. Another object of the present invention is to provide a bearing rotation preventing device for a shaft to be heated, which is provided with a heat transfer means for coupling a heat source for heating the shaft and an outer ring of the bearing. The heat transfer means may be a good heat conductor such as a metal, a heat transfer device using a heat medium such as a heat pipe, or a fluid circulation device. The specifications should be determined so that the heat transfer amount matches the heat transfer amount transmitted to the inner ring.

[0008]

FIG. 1 shows a conceptual diagram of an apparatus for realizing the method of the present invention. An electric heater 14 is provided outside the bearing outer ring 3 to heat the outer ring 3. The temperature of the shaft 1 is measured by the sensor 10 in the immediate vicinity of the bearing, and the temperature of the outer ring 3 is measured by the sensor 11 and input to the control device 12, and the control device 12 adjusts the power supply 13 so that the difference becomes zero. Then, the heating amount of the electric heater 14 is adjusted, and the outer ring 3 is controlled so as to be at the same temperature as the shaft 1. With this device, the outer ring 3 and the shaft 1 (from cold to hot) can be regarded as having substantially the same temperature as the inner ring 2
Can be maintained at substantially the same value, the amounts of thermal expansion of the bearing outer ring 3 and the inner ring 2 are also substantially equal, and bearing rotation failure due to a reduction in the rolling gap does not occur. Further, since it is not necessary to increase the rolling gap during the cold operation, abnormal vibration of the bearing due to unbalance of the shaft system does not occur.

In this case, the temperature of the shaft 1 is measured instead of the inner ring 2 because the temperature of the shaft 1 is generally easier to measure than that of the inner ring 2. Of course, the temperature of the inner ring 2 may be directly measured. FIG. 2 shows another embodiment. FIG. 2 shows a cantilevered in-furnace fan. The inside of the furnace 25 is on the left side of the heat insulating wall 22, and the impeller 21 is attached to the inside of the furnace 25. The shaft 1 is exposed in the furnace 25, and the shaft end temperature in the furnace is about 700 degrees, and the temperature of the shaft near the bearing inner ring is about 200 degrees. A copper heating element 24 is disposed outside the bearing outer ring 3, and a copper heat conducting section 23 is connected to the heating element 24 as a heat transfer unit that supplies heat from the furnace through the heat insulating wall 22.

During the hot operation, the heating element 2 is
4 is heated and raises the temperature of the bearing outer ring. Heat conducting part 23
Adjusts the heat transfer amount in advance so that the temperature of the outer ring 3 and the temperature of the shaft 1 become substantially equal during the hot operation. Since the heat conducting unit 23 transfers heat from the furnace interior 25 to the heating element 24, the temperature of the outer race 3 is low when the furnace interior is cold, and the outer race 3 is heated as the furnace interior temperature rises. Therefore, it is possible to automatically maintain the rolling gap of the rolling bearing at a desired value from a cold time to a hot time without using a heating source such as a temperature control device, a sensor, and an electric heater. .

FIG. 3 shows the effect of the present apparatus. Furnace temperature on the horizontal axis,
On the vertical axis, the shaft temperature at the bearing portion and the temperature of the outer ring 3 are plotted. In the conventional bearing 2, the temperature of the outer ring 3 is as shown by a curve 32, and does not rise as much as the temperature of the shaft 1 shown by the curve 31. In the apparatus according to the present invention, the temperature of the shaft 1 and the temperature of the outer ring fluctuated at approximate values as shown by a curve 33, and no rotation failure of the bearing occurred. Further, since the bearing having the optimum rolling gap can be selected regardless of the cold or hot state, no abnormal vibration of the bearing occurred.

Although the horizontal axis is shown in FIGS. 1 and 2, the same applies to the vertical axis. Further, in FIG. 2, the heating body 13 and the heat conducting portion 14 are made of a copper ring and a rod, but any material may be used as long as it is resistant to high temperatures and has a suitable heat transfer property.

[0013]

According to the method of the present invention, by compensating for the temperature difference between the outer ring and the inner ring of the bearing in the rolling bearing fitted on the shaft to be heated, the temperatures of the inner and outer rings of the bearing become substantially equal, and the amount of thermal expansion is increased. And the bearing rotation does not occur due to the reduced rolling gap. Further, since the optimal rolling gap can be maintained from cold to hot, abnormal vibration of the bearing due to excessive rolling gap does not occur.

The apparatus of the present invention can efficiently carry out the above method of the present invention. Further, in a device for heating the bearing outer ring with heat obtained from the same heating source for heating the inner ring, it is possible to automatically achieve isothermal temperature without requiring a temperature measuring device or a separate heating control device.

[Brief description of the drawings]

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

FIG. 2 is an explanatory diagram showing another embodiment.

FIG. 3 is a graph showing the effect of the present invention.

FIG. 4 is a conceptual diagram of a general heated shaft system.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 shaft 2 bearing inner ring 3 bearing outer ring 4 bearing rolling element 5 bearing nut 6 burner (heating source) 10, 11 temperature sensor 12 control device 13 power supply 14 electric heater 21 impeller 22 heat insulating wall 23 heat conducting part 24 heating element 25 furnace 31 32,33 curve

Claims (3)

[Claims] 1. A method for preventing a bearing from rotating poorly on a heated shaft, wherein the outer ring of the rolling bearing fitted to the heated shaft is heated to compensate for a temperature difference between the outer ring and the inner ring of the bearing. 2. A heating means for heating an outer ring of a rolling bearing, a temperature measuring means for measuring temperatures of a shaft and an outer ring in the vicinity of the bearing, and a temperature difference between the temperature measuring means and the temperature difference being zero. And a controller for controlling the amount of heating of the heating means as described above. 3. A device for preventing poor rotation of a bearing of a heated shaft, comprising a heat transfer means for connecting a heat source for heating the shaft and an outer ring of the bearing.