JPH07185994A - Cooling of built-in motor - Google Patents

Abstract

PURPOSE:To extend the life span of a bearing as well as to prevent a seizure accident due to rising of bearing surface pressure by restraining thermal conduction to a main spindle by way of strongly cooling a rotor of a built-in motor only at the time of high output. CONSTITUTION:A plural number of through grooves in the shaft direction are provided on the inner periphery of a sleeve 5 having a rotor 3B adhered on a main spindle 2, and the rotor 3B is cooled by a cooling effect due to sudden expansion of air by jetting air toward the through grooves from jet nozzles having a restriction effect of a nozzle 7 or 9 so as not to jet against the flow of air by fins 5b, 5c changing in accordance with the direction of rotation only at the time when the output of a built-in motor 3 exceeds a set value.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotor cooling method for a built-in motor incorporated in a headstock or head of a machine tool such as a lathe or a machining center.

[0002]

2. Description of the Related Art Conventionally, as shown in FIG. 5, a cooling method for a built-in motor incorporated in a spindle head or a headstock is such that a stator 103 is attached to a main body 101 via a sleeve 102, and a spiral wire is provided on the outer circumference of the sleeve 102. Groove 1
There are a method of cooling the stator side by flowing a cooling liquid in 02a, and a method of cooling the rotor side known in Japanese Patent No. 92-29202 as shown in FIG. The latter is the spindle 10.
4, the rotor 106 is attached by the sleeve 105 to form an annular space between the main shaft 104 and the sleeve 105, and the flow paths 105a and 105b are provided on both sides of the annular space, and suction is performed between the flow path 105b and the lid 107 on the inlet side. Fin 1 for
No. 05c and the fins 105d for exhausting are provided between the flow path 105a and the lid 107 on the outlet side, and the rotor is cooled by passing air through the annular space by the rotation of the main shaft.

[0003]

In the method of cooling the stator side described in the prior art, heat generation of the rotor is transmitted to the main shaft and the main shaft expands, which causes an increase in bearing surface pressure and shortens the life of the bearing. In the worst case, there is a problem that the bearing will be damaged, and the method of cooling the rotor side of Japanese Patent No. 92-29202 is a powerful cutting method only by cooling the annular space with small fins for suction and discharge. If the amount of heat generated increases due to an increase in motor load due to high speed rotation or the like, cooling will not catch up, and the spindle temperature will rise and the service life of the bearing tends to be shortened. The present invention has been made in view of the above problems of the prior art, and an object thereof is to supply compressed air from the outside only when the motor load is large and the calorific value is large to make the rotor strong. An object of the present invention is to provide a method for cooling a rotor of a built-in motor for cooling.

[0004]

In order to achieve the above object, a method for cooling a built-in motor according to the present invention is to inject compressed air from one end into an axial through groove of a sleeve for fixing a rotor of the built-in motor to a main shaft, The rotor is cooled by being placed on the air flow in the through groove due to the fins on both ends of the sleeve. Further, the rotor is cooled by utilizing the cooling effect due to the rapid expansion of the air when the compressed air is injected into one end of the through hole. Further, the compressed air is injected when the output of the built-in motor is equal to or more than the set value. In addition, the injection direction of the compressed air is changed according to the forward / reverse rotation of the rotor.

[0005]

The output of the drive unit during rotation of the built-in motor is detected and compared with a preset value that is stored in advance. When it exceeds the preset value, compressed air is injected from one end into the axial through groove of the sleeve between the rotor and the main shaft. Then, by utilizing the cooling effect due to the rapid expansion of air, the cooled air is caused to flow through the through groove to cool the rotor. At this time, the direction of injecting the compressed air is switched by the rotation direction so as not to oppose the flow in the through groove due to the fins on both ends of the sleeve.

[0006]

EXAMPLES Examples will be described with reference to the drawings. In a spindle head of a machining center, a spindle 2 is rotatably supported by a spindle head main body 1 by a plurality of bearings.
It is rotated forward or backward by the built-in motor 3 driven by C. The stator 3A of the built-in motor 3 has a sleeve 4
Is fitted to the spindle head main body 1 via a groove, and a spiral groove 4a through which the cooling liquid passes is engraved on the outer periphery of the sleeve 4, and the cooling liquid is caused to flow in the spiral groove to cool the stator 3A. . The rotor 3B of the built-in motor 3 is fixed to the main shaft 2 by a sleeve 5, and the sleeve 5 has axial through grooves 5a on the inner circumference at equal intervals on the circumference as shown in FIGS. Fins 5b and 5c are formed on the end surface of the rear side (right side) for air intake during forward rotation, and front side (left side) for air exhaust, and in reverse rotation, front side fin 5c is for air intake, The fins 5b on the rear side are for discharging air.

The jet outlet 7a of the air nozzle 7 at the tip of the air supply passage 6a formed in the rear bearing housing 6 is opened near the rear end surface of the sleeve 5 so that the air supply passage 6a can be obtained with a throttling effect. The diameter is smaller than the diameter.
Further, the air nozzle 9 at the tip of the air supply passage 8a formed in the block 8 fixed to the spindle head main body 1 is opened near the tip surface of the sleeve 5, and the ejection port is similarly formed to have a diameter smaller than the diameter of the air supply passage 8a. Has been done. Further, the spindle head body 1 is provided with air vent holes 1a and 1b at two locations.

As shown in the block diagram of FIG. 1, the air circuit for sending the compressed air to the air supply paths 6a and 8a has an electromagnetic on / off valve 11 and an electromagnetic switching valve arranged in series with the air source. It is supplied via 12. An electric circuit that controls the two solenoid valves is a C-axis drive unit 14 that supplies drive power to the built-in motor 3 according to the output signal of the NC servo unit 13. Output detector 1 for detecting this output
5. A set value storage unit 16 that stores a set value preset based on the amount of heat generated on the rotor side by this output. An output comparison unit 17 that compares the set value and the detected output. An on / off signal output unit 18 that outputs an on / off signal according to the output signal of the comparison unit 17.
Forward / reverse rotation detection unit 1 that detects forward / reverse rotation of the motor
9. It is configured by a switching signal output unit 21 that outputs a switching signal in response to the signal of the detection unit 19.

The operation of this embodiment will be described below with reference to the flow chart of FIG. In step S1, the output from the drive unit 14 to the rotating built-in motor 3 is detected. At this time, the stator 3A of the built-in motor
The side is cooled by the cooling liquid flowing in the spiral groove 4a on the outer circumference of the sleeve 4, and the rotor 3B side is cooled relatively gently by the air by the fins 5a, 5b flowing in the through groove 5a of the sleeve 5. In step S2, it is confirmed whether the output to the motor is larger than a preset value stored in advance. If NO, the process returns to step S1 to continue monitoring.

If YES in step S2, it is confirmed in step S3 whether or not the rotation is normal, and YES.
When the solenoid on / off valve 11 opens, the solenoid switching valve 12
The compressed air is sent through the air supply passage 6a on the rear side, and the nozzle 7 has the throttling effect.
Due to the cooling effect due to the rapid expansion when jetted more vigorously than a, cold air flows into the through groove 5a and the rotor 3B
To cool. If NO in step S3, in step S5, the front air supply passage 8a
The pressurized air is sent to the nozzles, and the air is jetted from the jet port having the throttling effect of the nozzle 9 to cool the rotor 3B as described above.

Next, in step S6, it is confirmed whether or not the output to the motor has become less than or equal to the set value, and if NO, the process returns to step S3. If YES, the timer is set to start counting in step S7, and it is confirmed in step S8 whether the elapsed time has reached the set time. If NO, the output to the motor is performed in step S9 during this time. Monitor whether the value exceeds the set value. If NO, that is, if the motor output remains below the set value, the process returns to step S8 to continue monitoring, and if YES, that is, if the set value is exceeded, in step S10, the count time of the timer is counted. After returning to zero, the process returns to step S6.

If YES in step S8, in step S11, the solenoid on / off valve 11 is closed to stop the supply of pressurized air, the injection of air from the nozzle 7 or 9 is stopped, and cooling by injection is performed. Cut, fin 5
Only relatively mild cooling with b or 5c. Next, in step S12, it is confirmed whether or not the spindle stop command is issued from the NC. If NO, the process returns to step S1. If YES, the process ends. It should be noted that although this embodiment has described the rotor cooling method of the built-in motor of the spindle head of the machining center, it can be applied to the rotor cooling method of the built-in motor of the headstock or spindle head of other machine tools such as lathes, milling machines, and drilling machines. Of course, of course.

[0013]

Since the present invention is configured as described above, it has the following effects. In addition to the fin cooling method for cooling the rotor of the built-in motor, when the output value to the built-in motor exceeds the set value, air is ejected from the ejection port that has a throttling effect and the cooling effect due to rapid expansion Since the rotor is cooled by using, the heat is not easily transferred to the main shaft by cooling the rotor in a timely manner at the time of high output with a large amount of heat generation, and it is possible to suppress an increase in bearing surface pressure and rotate at a higher speed. It is possible to reduce the number of accidents that damage the bearing and extend the life of the bearing. Further, since the air injection from the nozzle is limited when the motor output is large, it is possible to suppress unnecessary air consumption and prevent the adverse effect due to overcooling, and it is possible to minimize the injection noise.

[Brief description of drawings]

FIG. 1 is a sectional view of a spindle head having a rotor cooling device according to an embodiment of the present invention, and a block diagram of an air circuit and an electric control circuit.

FIG. 2 is an enlarged view of a rotor fixing sleeve and an air jet portion.

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

FIG. 4 is a flowchart of the operation of this embodiment.

FIG. 5 is a sectional view of a spindle head having a prior art stator cooling device.

FIG. 6 is a cross-sectional view of a spindle head having a conventional rotor cooling device.

[Explanation of symbols]

1 main spindle head body 2 main spindle 3 built-in motor 3A stator 3B rotor 4 stator side sleeve 5 rotor side sleeve 5a through groove 7,9 nozzle 15 output detection unit 16 set value storage unit 17 output comparison unit

Claims (4)

[Claims] 1. A rotor for cooling a built-in motor is cooled by injecting compressed air from one end into an axial through-groove of a sleeve for fixing the rotor to a main shaft, and letting the fins at both ends of the sleeve carry the flow of air in the through-groove. A method for cooling a built-in motor, which is characterized by being performed. 2. The method for cooling a built-in motor according to claim 1, wherein the rotor is cooled by utilizing a cooling effect due to rapid expansion of air when compressed air is injected into one end of the through hole. . 3. The built-in motor cooling method according to claim 1, wherein the compressed air is injected when the output of the built-in motor is equal to or more than a set value. 4. The cooling method for a built-in motor according to claim 1, wherein the injection direction of the compressed air is changed in accordance with the normal / reverse rotation of the rotor.