JP2001087949A - Rotor-shaft shrinkage fitting method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a shaft from being bent when it is to be shrinkage fitted in the rotor of a motor. SOLUTION: The rotor 7 of a motor is immersed in a oil L heated to 150 deg.C approximately, and a shaft 11 at room temperature is inserted into the rotor 7. The shaft 11 is heated to a temperature approximately the same as 150 deg.C and then cooled. According to this process, the bend of the shaft 11 is lessened.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shrink fit method for fitting a rotor of a motor and a shaft of the motor.

[0002]

2. Description of the Related Art Conventionally, a rotor and a stator of a built-in motor are usually supplied to a machine manufacturer by a motor manufacturer.

[0003] Machine builders manufacture shafts that are fitted and fixed to rotors so as to be compatible with each machine. The machine manufacturer shrinks the shaft and rotor. Metal machine tools,
For example, in a grinding machine, a built-in motor is used for a grinding wheel head, which is effective in reducing the size of the grinding wheel head.

In a machining center, a built-in motor is used for a spindle head, which is also effective in reducing the size of the spindle head. Therefore, built-in motors are widely used in metal machine tools.

[0005]

As shown in FIG. 2, when the rotor 7 is heated in the air and the normal-temperature shaft 11 is fitted into the rotor 7 and cooled, the shaft 11 may bend δ. is there.

Accordingly, an object of the present invention is to provide a method of shrink-fitting a rotor and a shaft which can reduce the bending generated in the shaft.

[0007]

Conventionally, shrink-fitting of a rotor to a shaft has been performed in the air, and the center line of the shaft does not coincide with the center line of the rotor. Therefore, the present inventor has found that bending occurs after shrink fitting and the stress becomes non-uniform, and even if correction is performed by grinding after shrink fitting, bending δ occurs due to a temperature rise due to grinding heat.

The inside diameter 7a of the heated rotor 7 is enlarged, and the shaft 11 at room temperature is in a loose fit state. Therefore, as shown in FIG. 3, if the shaft 11 is inserted into the rotor 7 such that the center of the normal-temperature shaft 11 coincides with the center of the heated rotor 7, the bent δ of the shaft 11 after natural cooling hardly occurs.
However, as shown in FIG. 4, when the shaft 11 is inserted eccentrically by the amount of eccentricity ７ with respect to the rotor 7, the bend δ of the shaft 11 after natural cooling increases.

Here, the length of the rotor 7 is 70 mm,
The length including the portion fitted to the rotor 7 is 270 mm,
FIG. 5 shows the relationship between the eccentricity △ and the bending δ when the diameter of the shaft 11 is 50 mm.

FIG. 5 shows the amount of protrusion (mm) of the shaft 11 from the rotor 7 on the horizontal axis, and the bending (μm) of the shaft 11 on the vertical axis. The curves in the figure show the eccentricity △ of the shaft 11 and the rotor 7 as parameters. As is apparent from the drawing, the bending δ of the shaft 11 increases as the eccentricity △ increases.

In consideration of the above, the reason why the rotor bends δ as described above is that the rotor 7 is formed by laminating thin plates and that both ends are covered with rings. Think from the point. If the rotor 7 and the shaft 11 are eccentric when the shaft 11 is inserted into the heated diameter-increased rotor 7, the inner circumference of the rotor 7 is controlled by the room-temperature shaft 11 at the closest portion between the outer circumference of the shaft 11 and the inner diameter of the rotor 7. Is cooled, and the rotor 7 contracts in an irregular manner. This can be seen from the fact that the larger the amount of eccentricity △, the greater the bending of the shaft 11 as described above.

The present invention which solves the problem based on such considerations is as follows.

According to a first aspect of the present invention, in a method for shrink-fitting a rotor and a shaft of an electric motor, a non-heated shaft is inserted into the rotor while the rotor is immersed in heated oil. A shrink-fitting method for a rotor and a shaft, characterized in that the rotor and the shaft are kept in oil until the temperature becomes substantially the same as the temperature of the rotor, and then cooled.

A second invention according to the present application is characterized in that the cooling is performed until the oil reaches room temperature with the rotor and the shaft immersed in the oil. This is a shrink fit method.

A third invention according to the present application is the method of shrink-fitting a rotor and a shaft according to the first invention, wherein the cooling is performed by taking a rotor with a shaft out of oil and cooling it in the atmosphere. It is.

According to a fourth aspect of the present invention, in the first aspect, the non-heated shaft is a shaft cooled to room temperature or below room temperature. This is a method of shrink-fitting the rotor and shaft.

According to a fifth aspect of the present invention, there is provided the rotor and the shaft according to any one of the first to fourth aspects, wherein the cooling is natural cooling, forced air cooling, or liquid cooling. This is a shrink fit method.

[0018]

Embodiments of the present invention will be described below with reference to the drawings.

(Embodiment 1) FIG. 1 shows a state in which the present invention is implemented.

As an apparatus for carrying out the present invention, oil L
And a heater 2 for heating the oil L in the container 1 and a temperature sensor 3 for detecting the temperature of the oil L
And a temperature controller 5 for inputting a signal from the temperature sensor 3 and controlling the heater 2 to control the temperature of the oil L to the temperature set by the temperature setting device 4, and displaying the temperature detected by the temperature sensor 3. A temperature indicator 6. Here, the temperature sensor 3 is, for example, a thermistor. The heater 2 is, for example, an electric resistance heating element. In addition, the temperature display 6 displays the temperature and, when a signal corresponding to the set temperature of the temperature setting device 4 is input from the temperature sensor 3 to the control device 5, displays the sound, light or the like. At the bottom of the container 1, a stand 8 for setting the rotor 7 is provided.

The operation of the present invention will be described using the above device.

The oil L in the container 1 has a temperature at which shrink fitting is performed by the heater 2 and the above-mentioned temperature control device.

The rotor 7 is placed on the table 8. Oil L is the amount of oil L that becomes oil level 9 so that all rotors 7 are in oil L.
Are stored in the container 1. At this time, the temperature of the oil L is adjusted to a desired temperature, but the temperature of the oil L fluctuates downward due to the heat capacity of the rotor 7 which was at room temperature in the air. Therefore, the heat capacity of the oil needs to be sufficiently large. The heater 2 is operated by a temperature control device so that the oil L has a constant temperature. Therefore, the process waits until the rotor 7 has the same temperature as the desired oil L. Here, when the temperature indicator 6 indicates that the temperature of the oil L has dropped to the desired temperature again, the rotor 7 and the oil L are at substantially the same temperature.

Incidentally, the inner diameter 7a of the rotor 7 and the fitting portion 11a of the shaft 11 to the inner diameter 7a of the rotor 7 have a dimensional relationship with a shrink fit. Therefore, the inner diameter 7a of the rotor 7 in the state where the rotor 7 is heated to almost the same temperature with the oil L as described above is the fitting portion 11 of the shaft 11 at normal temperature.
The shrink fitting allowance is determined in accordance with the temperature of the oil L so as to be larger than the outer diameter of a and to be a loose fit.

When the oil L reaches a desired temperature again after the rotor 7 is immersed in the oil L, the temperature indicator 6 notifies. Then, the fitting portion 11 a of the shaft 11 at room temperature in the air is inserted into the inner diameter 7 a of the rotor 7. Here, the shaft 11 may be cooled by a refrigerating device or the like. That is, the shaft 11 only needs to be non-heated. When the shaft 11 is cooled and shrink-fitted, the heating temperature of the rotor 7 can be reduced.

Then, the shaft 11 is heated mainly by the rotor 7 at the fitting portion 11a, the portion of the oil L other than the fitting portion 11a is heated by the oil L, and the shaft 11 expands in diameter.

At this time, at the portion where the inner diameter 7a of the rotor 7 and the fitting portion 11a of the shaft 11 are in contact with each other, the cooling rate is extremely lower than that in the atmosphere due to the oil L. Therefore, even if the shaft 11 is eccentrically inserted into the rotor 7, the function of the shaft 11 to cool the rotor 7, or conversely, the function of the rotor 7 to heat the shaft 11, is made uniform in the circumferential direction. In this state, since the shaft 11 is inserted into the rotor 7, the occurrence of the bending δ of the shaft 11 is suppressed.

Here, after the temperature of the rotor 7 and the shaft 11 reaches substantially the same temperature, for example, 150 ° C., the heating of the oil L by the heater 2 is stopped, and the oil L is cooled to room temperature while the rotor 7 and the shaft 11 are immersed in the oil L. Allow to cool naturally.

After cooling, the rotor 7 with the shaft 11 is pulled out of the oil L.

In the above, the oil L is selected from the relationship between rust prevention and heating temperature. The kind of oil is acceptable as long as it does not ignite at about 200 ° C. and has a rust-preventive action. Although the heating temperature varies depending on the shrink fit and the type of the oil L, about 150 ° C. is used as the heating temperature because the member to be heated is the rotor 7.

According to the present embodiment, even if the shaft 11 shrink-fitted to the rotor 7 is inserted eccentrically into the inner diameter 7a of the rotor 7, the bending δ remains very small.

(Embodiment 2) In Embodiment 1, the rotor 7 at normal temperature is immersed in the heated oil L. Embodiment 2
The oil L was heated after the rotor 7 at normal temperature was immersed in the oil L at normal temperature. Then, when the temperature of the oil L reaches a predetermined shrink fit, the temperature of the rotor 7 also becomes substantially the same as the temperature of the oil. Then, the non-heated shaft 11 is inserted into the rotor 7. Subsequent steps are the same as in the first embodiment.

(Embodiment 3) In this embodiment, the oil L
Is heated to a predetermined temperature at which shrink fitting is performed. On the other hand, rotor 7
Is heated to a temperature substantially equal to a predetermined temperature to be shrink-fitted by, for example, an electric furnace (not shown). The heated rotor 7 is taken out of the electric furnace and immersed in the oil L in the container 1,
Place on the table 8. If necessary, the temperature of the oil L detected by the temperature sensor 3 is confirmed to be the quenching temperature. If the temperature has not reached the quenching temperature, the unheated shaft 11 is inserted into the rotor 7 after heating again. What was necessary was that the rotor 7 was previously heated to a temperature higher than the shrink fit in anticipation of the temperature drop due to the elapse of the time required for the transfer process of the rotor 7 after heating in the electric furnace. This is because, even in this case, variations in the temperature drop cannot be avoided.

The operation after the shaft 11 is inserted into the rotor 7 mounted on the table 8 and the type of the oil L are the same as in the first embodiment.

(Embodiment 4) Embodiment 4 is different from any one of Embodiments 1 to 3 in that the cooling after shrink fitting is performed by natural cooling in the oil L instead of shrink fitting. After axis 1
The rotor 7 is taken out into the atmosphere and allowed to cool in the atmosphere.

The rotor 7 with the shaft 11 after shrink fitting is taken out of the oil L and allowed to cool.
May be performed immediately after the temperature difference becomes small, or after the shrink fitting, the temperature of the oil L has decreased to some extent, and the temperature difference between the ambient temperature and the rotor 7 with the shaft 11 may be reduced.

Instead of cooling in the atmosphere, forced air cooling may be performed by a fan or the like.

(Fifth Embodiment) In a fifth embodiment, a rotor 7 with a shaft is introduced into oil instead of cooling by air or forced air cooling in the fourth embodiment. The temperature of the oil may be lower than the temperature of the rotor with the shaft, for example, normal temperature. When a cleaning liquid is used as the oil, cleaning of the shaft-equipped rotor 7 can be performed simultaneously.

[0039]

According to a first aspect of the present invention, there is provided a method for shrink-fitting a rotor and a shaft of an electric motor, wherein a non-heated shaft is inserted into the rotor while the rotor is immersed in heated oil. By keeping the shaft in oil until the temperature of the shaft becomes substantially the same as the temperature of the rotor and then cooling, the bending of the shaft can be reduced.

According to a second aspect of the present invention, in the first aspect, the cooling is performed until the oil reaches a normal temperature in a state where the rotor and the shaft are immersed in the oil. The transfer process of the attached rotor is not required, and the entire process is simple.

According to a third aspect of the present invention, in the first aspect, the number of containers to be prepared can be reduced by taking out the rotor with the shaft from the oil and cooling it in the atmosphere. In addition, equipment costs can be reduced. In addition, the cooling time can be shortened.

[0042] The fourth invention according to the present application comprises the first to third aspects.
In any one of the above inventions, the non-heated shaft is a shaft cooled to room temperature or lower than room temperature. When the shaft is cooled to a temperature lower than the normal temperature, the heating temperature of the rotor can be lowered, and the range of choice of the insulating material of the rotor is expanded, and it is possible to cope with various types of rotor.

The fifth invention according to the present application provides the first to fourth aspects.
In any one of the above inventions, the cooling is natural cooling, forced air cooling, or liquid cooling. Here, according to the natural cooling, the temperature change between the shaft and the rotor during the cooling process is small, so that the temperature difference between the shaft and the rotor is always small during cooling.
According to forced air cooling or liquid cooling, the cooling process can be shortened.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing an embodiment of the present invention.

FIG. 2 is a side view showing the bending of a shaft shrink-fitted to a rotor.

FIG. 3 is a cross-sectional view at right angles to an axis showing a relationship between a rotor and a shaft when shrink-fitting.

FIG. 4 is a cross-sectional view at right angles to the axis showing the relationship between the rotor and the shaft during shrink fitting.

FIG. 5 is a diagram showing bending of a shaft fitted into a rotor.

[Explanation of symbols]

 L ... Oil 1 ... Container 2 ... Heater 3 ... Temperature sensor 4 ... Temperature setting device 5 ... Temperature control device 6 ... Temperature display 7 ... Rotor 7a ... Inner diameter 8 ... Stand 9 ... Oil level 11 ... Shaft 11a ... Fitting part

Claims (5)

[Claims] 1. A method for shrink-fitting a rotor and a shaft of an electric motor, wherein a non-heated shaft is inserted into the rotor while the rotor is immersed in heated oil, and the shaft has substantially the same temperature as the temperature of the rotor. A method of shrink-fitting a rotor and a shaft, wherein the method is carried out by holding in oil until a temperature is reached and then cooling. 2. The shrink-fitting method for a rotor and a shaft according to claim 1, wherein the cooling is performed until the oil reaches room temperature while the rotor and the shaft are immersed in the oil. 3. The shrink-fit method for a rotor and a shaft according to claim 1, wherein the cooling is performed by taking out the rotor with the shaft from the oil and cooling it in the atmosphere. 4. The shrink-fitting method for a rotor and a shaft according to claim 1, wherein the non-heated shaft is a shaft cooled to a room temperature or lower than a room temperature. 5. The shrink-fitting method for a rotor and a shaft according to claim 1, wherein the cooling is natural cooling, forced air cooling, or liquid cooling.