JP2018043316A - Oil cooler and method of controlling the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an oil cooler and a method of controlling the same for controlling a cooling performance earlier, in response to a rise in the temperature of a main spindle head provided with a spindle rotating with a tool mounted in a machine tool.SOLUTION: A returned oil temperature, which is detected by a temperature detection sensor 22 for cooling oil, after cooling a spindle head is corrected on the basis of the rotation rate of a motor 45 for rotating a main spindle. It is determined whether a temperature calculated by subtracting a reference temperature set for a machine tool 1 from the temperature after the correction is within a prescribed temperature range or not. If determined within the prescribed temperature range, rotation rate information of the motor 45 is set in an input enabled state. Further, whether the calculated temperature is within the prescribed temperature range or not is to be determined again, and if determined not within the prescribed temperature range, it is determined whether the rotation rate of the motor 45 has changed more than a prescribed range or not. If determined so changed, on the basis of data stored in advance, the rotation rate of a motor 7A of a compressor 7, the rotation rate of a fan motor 9A for cooling a condenser 8, and the opening of an electronic expansion valve 11 are controlled for a prescribed time.SELECTED DRAWING: Figure 3

Description

  The present invention relates to an oil cooler in which cooling oil is circulated so as to cool a spindle head having a spindle that is rotated by a tool attached to the machine tool, and a control method therefor.

  Regarding this type of oil cooler, JP-A-2016-36900 (see Patent Document 1) and the like are known. Generally, the main shaft of various machine tools is affected by high-speed rotation, and the bearings and gears are thermally deformed due to heat generation. This results in misalignment of the shaft and affects machining accuracy. Cooling is performed while circulating cooling oil. . In this case, when the machine tool is operated, the amount of heat generation increases as the rotational speed of the motor that rotates the spindle to which the tool is attached increases, so the spindle head provided with the spindle is cooled. Since the temperature of the cooling oil rises, the cooling oil temperature after the cooling is detected to control the cooling capacity of the oil cooler.

Japanese Patent Laid-Open No. 2006-36900

  However, the cooling oil is circulated so as to cool the spindle head, and the temperature of the cooled cooling oil is detected. However, the cooling oil in the oil tank that stores the cooling oil is detected. Since it takes a considerable time for the temperature to rise, it takes a considerable time until the detected temperature of the cooling oil after cooling rises, and the response time is long and the cooling capacity of the oil cooler is increased. There was a problem that control was delayed.

  Accordingly, the present invention provides an oil cooler and a control method therefor, in which the cooling capacity can be controlled early in accordance with the temperature rise of the spindle head having a spindle that rotates with a tool attached to a machine tool. Aimed at

For this reason, in the first invention, the circuit for circulating the cooling oil to the machine tool, the compressor for compressing the refrigerant, and the heat of the gaseous refrigerant compressed by the compressor are radiated and liquefied. A condenser, an electronic expansion valve for expanding and expanding the liquefied refrigerant, and heat exchange with the cooling oil returned from the machine tool by the refrigerant in a low-pressure and low-temperature gas-liquid mixed state expanded and reduced An oil cooler comprising a heat exchanger for storing the cooling oil,
A cooling oil temperature detecting device for detecting a return oil temperature, which is a temperature of the cooling oil after cooling a spindle head provided with a spindle that rotates with a tool attached to the machine tool;
Correction means for correcting the detected temperature detected by the cooling oil temperature detection device based on the number of revolutions of a spindle motor that rotates the spindle of the machine tool;
Calculation means for subtracting a reference temperature set for the machine tool from the temperature corrected by the correction means;
First determination means for determining whether the calculated temperature obtained by subtraction by the calculation means is within a predetermined temperature range;
Means for enabling input of rotational speed information of the spindle motor when the calculated temperature is determined to be within the predetermined temperature range by the first determining means;
A second determination means for determining again whether or not the calculated temperature is within the predetermined temperature range when the rotation speed information is in an input enabled state by the input enabled state;
Third determination means for determining whether the rotational speed of the spindle motor has changed by a predetermined range or more when the second determination means determines that the calculated temperature is not within the predetermined temperature range;
When it is determined by the third determining means that the change has occurred in the predetermined range or more, the number of rotations of the compressor motor of the compressor and the condenser for cooling the condenser based on the data stored in the storing means in advance. Control means for controlling the rotational speed of the fan motor of the blower and the opening of the electronic expansion valve for a predetermined time is provided.

Further, the second invention is a circuit for circulating cooling oil to a machine tool, a compressor for compressing refrigerant, and heat for radiating and liquefying heat of a gaseous refrigerant compressed by the compressor. A condenser, an electronic expansion valve for constricting and expanding the liquefied refrigerant, and for exchanging heat with the cooling oil returned from the machine tool by the condensated low-pressure low-temperature gas-liquid mixed state refrigerant An oil cooler control method comprising a heat exchanger for storing the cooling oil,
A cooling oil temperature detection device detects a return oil temperature, which is a temperature of the cooling oil after cooling a spindle head provided with a spindle that rotates with a tool attached to the machine tool,
The return oil temperature detected by the cooling oil temperature detection device is corrected based on the number of revolutions of a spindle motor that rotates the spindle of the machine tool,
Subtract the reference temperature set for the machine tool from the corrected temperature,
Determine whether the calculated temperature obtained by this subtraction is within a predetermined temperature range,
When it is determined that the calculated temperature is within the predetermined temperature range, the rotational speed information of the spindle motor can be input,
When the rotational speed information is ready for input, it is determined again whether the calculated temperature is within the predetermined temperature range,
When it is determined that the calculated temperature is not within the predetermined temperature range, it is determined whether the rotational speed of the spindle motor has changed by a predetermined range or more,
If it is determined that the change has occurred in the predetermined range or more, the number of rotations of the compressor motor of the compressor and the number of rotations of the fan motor of the blower for cooling the condenser based on data stored in the storage unit in advance And the opening degree of the electronic expansion valve is controlled for a predetermined time.

  According to the present invention, there is provided an oil cooler and a control method thereof capable of controlling the cooling capacity early in accordance with the temperature rise of a spindle head having a spindle that is rotated by a tool attached to a machine tool. can do.

It is a figure for showing circulation of a refrigerant and circulation of cooling oil in a machine tool and an oil cooler. It is a control block diagram. It is a figure which shows a flowchart. In order to cool the compressor, the compressor motor rotation speed of the compressor corresponding to the ratio of the detected actual rotation speed of the spindle motor to the maximum rotation speed of the spindle motor for rotating the spindle of the machine tool It is a table | surface which shows the rotation speed of the fan motor of this blower, and the predetermined pulse number applied to the motor for electronic expansion valves in order to open an electronic expansion valve.

  Hereinafter, an embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a diagram for showing the circulation of refrigerant in the machine tool 1 and the oil cooler 5 and the circulation of cooling oil as a cooling medium (cooling oil which is a cooling medium). Temperature control is performed so as to cool the spindle head having the spindle that is mounted and rotated.

  The oil cooler 5 includes a refrigerant circulation circuit 3 in the right part of FIG. 1 and an oil circulation circuit 4 in the left part, and is provided so as to cool the spindle head (including the spindle) of the machine tool 1. The refrigerant circulation circuit 3 is a circuit through which the refrigerant circulates, and the oil circulation circuit 4 is a circuit through which the cooling oil circulates between a heat exchanger 12 (described later) and the machine tool 1.

  First, the refrigerant circulation circuit 3 will be described. Gas refrigerant is compressed by a compressor 7 having a compressor motor 7A and sent to a condenser 8 as a heat exchanger. In the condenser 8, the heat of the gaseous refrigerant which has been compressed by the compressor 7 and whose temperature has risen is radiated and liquefied. The condenser 8 is cooled by air cooling by a condenser blower 9 provided with a fan motor 9A.

  Then, the refrigerant liquefied by the condenser 8 is removed of foreign matters by the strainer 10, and then passes through the electronic expansion valve 11 provided with an electronic expansion valve motor (in this embodiment, a pulse motor) 11A. In this case, the gas is squeezed and expanded to a low-temperature and low-pressure gas-liquid mixed state. This low-temperature and low-pressure gas-liquid mixed refrigerant flows into the heat exchanger (cooler) 12 and cools the cooling oil (cooling oil that is a cooling medium) stored in the heat exchanger 12. is there. The refrigerant in the gas-liquid mixed state takes the heat of the cooling oil in the heat exchanger 12 and vaporizes, and the cooling oil in the heat exchanger 12 can be efficiently cooled by the heat of vaporization. Then, the refrigerant that has flowed out of the heat exchanger 12 returns to the compressor 7 via the accumulator 14 that is a gas-liquid separator, and thus the refrigerant described above circulates in the refrigerant circulation circuit 3. Become.

  The refrigerant circulation circuit 3 has a reduced cooling capacity for cooling the cooling oil by flowing into the heat exchanger 12 without cooling a part of the gaseous refrigerant which has been compressed by the compressor 7 and whose temperature has risen. A bypass path 15 to be adjusted is added, and an electromagnetic valve 16 that is opened and closed by a solenoid 16A that is a bypass valve is provided in the bypass path 15.

  Reference numeral 18 denotes a high-pressure switch, which is a compressor protection switch that operates when the pressure of the refrigerant on the discharge side of the condenser 8 reaches a high pressure exceeding a predetermined pressure. When operated, the operation of the compressor 7 is stopped. It is.

  Next, the oil circulation circuit 4 will be described. An oil feed pump 20 provided in the oil circulation circuit 4 is driven by a motor 20A to circulate the cooling oil in the oil circulation circuit 4 at a constant flow rate.

  Then, after supplying the cooling oil from the machine tool 1 to the heat exchanger 12 through the pipe 23A, the cooling oil in the heat exchanger 12 is supplied to the oil feed pump 20 through the pipe 23B. Is sent to the machine tool 1 to cool the spindle head (including the spindle) of the machine tool 1.

  Accordingly, the cooling oil circulates in the oil circulation circuit 4, but after cooling the spindle head (including the spindle) in the machine tool 1, the cooling oil passes through the pipe line 23 </ b> A of the oil circulation circuit 4. The cooling oil returning to the inside of the heat exchanger 12 is detected as a return oil temperature by a cooling oil temperature detection sensor (cooling oil temperature detection device) 22 until it leaves the machine tool 1 and reaches the heat exchanger 12. The

  Next, in FIG. 2 which is a control block diagram, a microcomputer (hereinafter referred to as “microcomputer”) 25 which is a temperature control means includes the number of rotations of the compressor motor 7A of the compressor 7 and the fan 9. Temperature control is performed in order to cool the spindle head of the machine tool 1 by controlling the rotation speed of the fan motor 9A and the opening of the electronic expansion valve 11.

  The microcomputer 25 is connected to the CPU 26 via a bus line as a control means for controlling the oil cooler 5 in an integrated manner, and stores a program related to the control. A ROM (Read Only Memory) 27 and a RAM (Random Access Memory) 28 as storage means for storing various data are provided.

  A display device 30, an input device 31, and the like are connected to the CPU 26 of the microcomputer 25, which is a temperature control means, via an interface 29. The ROM 27 stores a program related to temperature control for cooling the spindle head of the machine tool 1 as shown in FIG.

  The CPU 26 serves as calculation (calculation) means, correction means, determination means, comparison means, command means, control means, and the like.

  The CPU 26 is connected to the cooling oil temperature detection sensor 22 that detects the temperature (return oil temperature) of the cooling oil that cools the spindle head of the machine tool 1 and returns to the heat exchanger 12. In addition, a rotational speed detection device 33 that detects the rotational speed of the compressor motor 7A of the compressor 7, a rotational speed detection device 34 that detects the rotational speed of the fan motor 9A of the blower 9, and the electronic expansion valve 11 A rotation angle detecting device 35 for detecting the rotation angle of the electronic expansion valve motor 11A is connected.

  The CPU 26 includes a compressor motor 7A for the compressor 7 via a drive circuit 37 and a solenoid 16A for the solenoid valve 16 via a drive circuit 38. The valve motor 11A is connected via a drive circuit 39, the fan motor 9A of the blower 9 is connected via a drive circuit 40, and the motor 20A of the oil feed pump 20 is connected via a drive circuit 41.

  In the present embodiment, the electronic expansion valve motor 11A of the electronic expansion valve 11 is configured by a pulse motor, and, for example, 500 pulse signals are output to the electronic expansion valve motor 11A via the drive circuit 39. Then, the opening of the electronic expansion valve 11 is fully opened, and the electronic expansion valve 11 starts to open with, for example, 50 pulse signals from the closed state.

  On the other hand, the machine tool 1 is also provided with a microcomputer (hereinafter referred to as “microcomputer”) 36 having a CPU, a RAM, a ROM, and the like, as described above. A reference temperature detection sensor (reference temperature detection device) 43 is connected to the microcomputer 36, and a spindle motor 45 for rotating the spindle and a rotation angle of the spindle motor 45 are grasped via a drive circuit 44. For this purpose, a rotational speed detection device 46 is connected.

  In the present embodiment, the temperature measured and detected by the reference temperature sensor 43 is set as a reference temperature in a part that is not affected by heat from a heat generation part (for example, an installation part such as a motor) of the machine tool 1. Is done.

  In the machine tool 1, the reference temperature detected by the reference temperature detection sensor 43 is sent to the oil cooler 5 by the microcomputer 36 and set and stored in the RAM 28 by the CPU 26 as a reference temperature. The temperature detected by the reference temperature detection sensor 43 is not limited to the method of setting and storing the temperature in the RAM 28 as the reference temperature. For example, using the display device 30 and the input device 31, an administrator ( A user may set the reference temperature and store it in the RAM 28 according to a command from the CPU 26.

  42 is a timer, and the CPU 26 is based on the data shown in the table of FIG. 4 stored in advance in the RAM 28, and the rotational speed of the compressor motor 7A of the compressor 7 and the fan motor of the blower 9. The time for controlling the rotational speed of 9A and the opening degree of the electronic expansion valve 11 is counted.

  The table of FIG. 4 shows that the compressor 7 corresponds to the ratio of the detected actual rotational speed of the spindle motor 45 to the maximum rotational speed of the spindle motor 45 that rotates the spindle of the machine tool 1. The number of rotations of the compressor motor 7A, the number of rotations of the fan motor 9A of the blower 9 for cooling the condenser 8, and a predetermined voltage applied to the electronic expansion valve motor 11A to open the electronic expansion valve 11 It is a table | surface which shows the number of pulses. Each data shown in FIG. 4 is an example, and is not limited to the data shown in FIG.

  With the above configuration, the operation of the embodiment of the present invention will be described below based on the flowchart of FIG. First, the reference temperature detection sensor 43 detects the reference temperature in the predetermined portion of the machine tool 1 and cools the spindle head of the machine tool 1 by driving the oil feed pump 20. The cooling oil temperature detection sensor 22 detects the temperature (return oil temperature) of the cooling oil that has returned from the machine 1 to the heat exchanger 12 and that has returned to the pipe 23A (step S01).

  In this case, the reference temperature detected by the reference temperature detection sensor 43 is sent from the microcomputer 36 of the machine tool 1 to the CPU 26 of the oil cooler 5, set in the RAM 28, stored and stored, and the cooling oil. The temperature of the cooling oil detected by the temperature detection sensor 22 is also stored and stored in the RAM 28 according to a command from the CPU 26.

  Next, as described above, the CPU 26 rotates the spindle of the machine tool 1 with the temperature detected by the cooling oil temperature detection sensor 22 (return oil temperature) of the cooling oil returned to the pipe line 23A. Control is performed so as to correct based on the rotational speed of the spindle motor 45 (step S02). That is, when the rotation speed changes in a predetermined time, for example, 1 minute, it is conceivable to correct the detected temperature of the cooling oil according to the change. Specifically, when the change in the rotation speed when increasing is large, when the change is middle, when the change is small, for example, a multiplier (in order of a small number, for example, “1.09”, respectively) at the detected temperature of the cooling oil. ”,“ 1.06 ”,“ 1.03 ”), and when the change in the rotation speed is small, medium, or large, for example, the detection of the cooling oil, respectively. The CPU 26 calculates and corrects the detected temperature of the cooling oil by multiplying the temperature by a multiplier (in order, for example, “0.97”, “0.94”, “0.91”).

  The correction method is not limited to the above-described method, and may be corrected in accordance with the number of rotations of the main shaft motor 45 that rotates the main shaft of the machine tool 1. As another method, for example, The number of rotations of the spindle motor 45 may be divided into certain ranges and obtained by multiplying the multipliers determined in accordance with these ranges, and various methods are conceivable.

  When the detected temperature of the cooling oil after correction with respect to a reference temperature, which will be described later, has decreased by minus 0.2 ° C., the solenoid valve 16 is turned on (ON) and opened to the same temperature. , Turn off (OFF) and close. That is, when the electromagnetic valve 16 is opened, a gaseous high-temperature refrigerant is mixed with a low-temperature refrigerant and reaches the heat exchanger 12, so that the cooling capacity is gradually reduced, and the electromagnetic valve 16 is closed. Then, high-temperature refrigerant does not mix and increases cooling capacity.

  Next, the CPU 26 calculates by subtracting the reference temperature detected in step S01 from the corrected cooling oil temperature obtained by multiplying the detected temperature of the cooling oil by the multiplier described above (step S03).

  Then, the CPU 26 determines whether or not the calculated temperature obtained by the calculation in step S03 is within a predetermined temperature range close to 0 (zero), for example, within plus or minus 0.1 ° C. (step S04). In this case, if it is not within plus or minus 0.1 ° C., the CPU 26 controls to return to step S01. Therefore, if it is determined in step S04 that the calculated temperature is not within ± 0.1 ° C., steps S01 to S04 are repeated.

  On the other hand, when the CPU 26 determines that the temperature is within ± 0.1 ° C. in the step S04, the CPU 26 detects the rotation speed of the compressor motor 7A of the compressor 7 from the rotation speed detection device 33. Information relating to the rotational speed of the spindle motor 45 that rotates the spindle of the machine tool 1 is made ready for input, and control is returned to step S01 (step S05).

  Next, the CPU 26 determines again whether or not the calculated temperature obtained in step 03 is within a predetermined temperature range close to 0 (zero), for example, within plus or minus 0.1 ° C. (step S06). In this case, when it is determined that the temperature is within plus or minus 0.1 ° C., the CPU 26 controls to return to step S01.

  Further, in this step S06, when the CPU 26 determines that the temperature is not within ± 0.1 ° C., the CPU 26 rotates the main shaft of the machine tool 1 based on information from the rotational speed detection device 46. It is determined whether the rotational speed of the motor 45 has changed by a predetermined range or more, for example, plus or minus 5% or more (step S07).

  In this case, if the CPU 26 determines that the change is not more than plus or minus 5%, the CPU 26 controls to return to step S01.

  On the other hand, when the CPU 26 determines that the change has increased by 5% or more, the CPU 26 determines that the compressor motor 7A of the compressor 7 is based on the data shown in the table of FIG. , The rotational speed of the fan motor 9A of the blower 9 and the opening of the electronic expansion valve 11 are controlled to start temperature control in order to cool the spindle head of the machine tool 1 (step S08). ).

  In this case, for example, the detected actual number of rotations of the main shaft motor 45 in the maximum number of rotations of the main shaft motor 45 that rotates the main shaft of the machine tool 1 (stored in the RAM 28 in advance). If the ratio is, for example, 60% or more and less than 65%, the CPU 26 controls as follows. That is, the CPU 26 causes the rotation speed of the compressor motor 7A of the compressor 7 to be 3220 rpm via the drive circuit 37, and the fan motor 9A of the blower 9 via the drive circuit 40. Further, 370 pulse signals are output to the expansion valve motor 11A of the electronic expansion valve 11 via the drive circuit 39 so that the rotation speed is 1000 rpm to 1100 rpm (or less than 1100 rpm). These are executed for a predetermined time (for example, 100 seconds) so that the expansion valve 11 has a predetermined opening (step S08). The opening degree of the electronic expansion valve 11 is fully opened by 500 pulse signals.

  Therefore, until the predetermined time has elapsed, as described above, the rotation speed of the compressor motor 7A of the compressor 7, the rotation speed of the fan motor 9A of the blower 9, and the opening of the electronic expansion valve 11 are increased. The degree will be controlled.

  When the timer 42 measures the predetermined time, the CPU 26 controls to return to step S01 (step S09).

  Conventionally, even if the number of revolutions of the spindle motor 45 that rotates the spindle of the machine tool 1 increases and the temperature of the spindle head rises, the temperature of the cooling oil in the heat exchanger 12 rises. Since it takes a considerable amount of time, the temperature of the cooling oil discharged from the machine tool 1 is detected after cooling the spindle head, and the compressor motor of the compressor 7 is detected based on the detected temperature. Even if the rotational speed of 7A, the rotational speed of the fan motor 9A of the blower 9 and the opening of the electronic expansion valve 11 are controlled, there is a problem that the response time is long and the control of the cooling capacity of the oil cooler is delayed. .

  However, according to this embodiment described above, the CPU 26 obtains information on the number of revolutions of the spindle motor 45 that rotates the spindle from the machine tool 1, and according to the number of revolutions of the spindle motor 45. Since the rotation speed of the compressor motor 7A of the compressor 7, the rotation speed of the fan motor 9A of the blower 9 and the opening of the electronic expansion valve 11 are controlled, the response time is long and the oil The problem of delaying the control of the cooling capacity of the cooler can be solved, and the control of the cooling capacity is advanced in accordance with the temperature rise of the spindle head provided with the rotating spindle attached with the tool in the machine tool 1. The oil cooler 5 can be provided.

  Although the embodiments of the present invention have been described above, various alternatives, modifications, and variations can be made by those skilled in the art based on the above description, and the present invention is not limited to the various embodiments described above without departing from the spirit of the present invention. It encompasses alternatives, modifications or variations.

DESCRIPTION OF SYMBOLS 1 Machine tool 4 Oil circulation circuit 5 Oil cooler 7 Compressor 7A Compressor motor 9 Blower 9A Fan motor 11 Electronic expansion valve 11A Expansion valve motor 22 Cooling oil temperature detection sensor 23A, 23B Pipe line 26 CPU
43 Reference temperature detection sensor 45 Spindle motor

Claims (2)

A circulation circuit for circulating cooling oil to the machine tool, a compressor for compressing the refrigerant, a condenser for dissipating and liquefying the heat of the gaseous refrigerant compressed by the compressor, and liquefied An electronic expansion valve for constricting and expanding the refrigerant, and heat exchange with the cooling oil returned from the machine tool by the constricted and expanded low-pressure and low-temperature gas-liquid mixed state, and the cooling oil An oil cooler comprising a heat exchanger for storing
A cooling oil temperature detecting device for detecting a return oil temperature, which is a temperature of the cooling oil after cooling a spindle head provided with a spindle that rotates with a tool attached to the machine tool;
Correction means for correcting the detected temperature detected by the cooling oil temperature detection device based on the number of revolutions of a spindle motor that rotates the spindle of the machine tool;
Calculation means for subtracting a reference temperature set for the machine tool from the temperature corrected by the correction means;
First determination means for determining whether the calculated temperature obtained by subtraction by the calculation means is within a predetermined temperature range;
Means for enabling input of rotational speed information of the spindle motor when the calculated temperature is determined to be within the predetermined temperature range by the first determining means;
A second determination means for determining again whether or not the calculated temperature is within the predetermined temperature range when the rotation speed information is in an input enabled state by the input enabled state;
Third determination means for determining whether the rotational speed of the spindle motor has changed by a predetermined range or more when the second determination means determines that the calculated temperature is not within the predetermined temperature range;
When it is determined by the third determining means that the change has occurred in the predetermined range or more, the number of rotations of the compressor motor of the compressor and the condenser for cooling the condenser based on the data stored in the storing means in advance. An oil cooler comprising a control means for controlling a rotation speed of a fan motor of a blower and an opening of the electronic expansion valve for a predetermined time. A circulation circuit for circulating cooling oil to the machine tool, a compressor for compressing the refrigerant, a condenser for dissipating and liquefying the heat of the gaseous refrigerant compressed by the compressor, and liquefied An electronic expansion valve for constricting and expanding the refrigerant, and heat exchange with the cooling oil returned from the machine tool by the constricted and expanded low-pressure and low-temperature gas-liquid mixed state, and the cooling oil An oil cooler control method comprising a heat exchanger for storing
A cooling oil temperature detection device detects a return oil temperature, which is a temperature of the cooling oil after cooling a spindle head provided with a spindle that rotates with a tool attached to the machine tool,
The return oil temperature detected by the cooling oil temperature detection device is corrected based on the number of revolutions of a spindle motor that rotates the spindle of the machine tool,
Subtract the reference temperature set for the machine tool from the corrected temperature,
Determine whether the calculated temperature obtained by this subtraction is within a predetermined temperature range,
When it is determined that the calculated temperature is within the predetermined temperature range, the rotational speed information of the spindle motor can be input,
When the rotational speed information is ready for input, it is determined again whether the calculated temperature is within the predetermined temperature range,
When it is determined that the calculated temperature is not within the predetermined temperature range, it is determined whether the rotational speed of the spindle motor has changed by a predetermined range or more,
If it is determined that the change has occurred in the predetermined range or more, the number of rotations of the compressor motor of the compressor and the number of rotations of the fan motor of the blower for cooling the condenser based on data stored in the storage unit in advance And a method of controlling the oil cooler, wherein the opening degree of the electronic expansion valve is controlled for a predetermined time.

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