JPH0717193A - Engraving machine controller - Google Patents

Abstract

(57) [Abstract] [Purpose] The object to be engraved is cooled to a constant temperature, and thereby the object to be engraved is hardened and stably fixed, and the engraving of the object to be engraved is reliably performed. A controller of an engraving machine having a cooling vise for hardening and fixing an object to be engraved by a cooling means, the parameter value of a parameter for the operation of an engraving machine body, and the object to be engraved at the parameter value. First storage means for storing the relationship with the optimum temperature, second storage means for storing the current parameter values of the main body of the engraving machine, detection means for detecting the temperature of the object to be engraved, and second storage means. A reading means for reading the optimum temperature of the object to be engraved in the parameter value stored in the means from the first storage means, and a comparison for comparing the temperature read by the reading means with the temperature detected by the detecting means. And a control unit that controls the cooling unit so as to be equal to the temperature read by the reading unit based on the comparison result of the comparison unit.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device for an engraving machine, and more particularly to a control device for an engraving machine for engraving an object to be engraved such as rubber or thermoplastic resin. The present invention relates to a control device of an engraving machine suitable for engraving a rubber stamp or the like.

[0002]

2. Description of the Related Art Conventionally, when engraving an object to be engraved with a soft material such as rubber or thermoplastic resin and engraving the object with the engraving machine to create a rubber stamp or the like, engraving When the engraving cutter or drill of the machine comes into contact with the object to be engraved, the object to be engraved is deformed, and the object cannot be engraved into a preset shape.

Therefore, even if the engraving object is cooled and hardened and fixed to the engraving machine, and the engraving cutter or drill of the engraving machine contacts the engraving object, the engraving object is deformed. It was suggested that there be no.

To fix the object to be engraved by cooling and hardening it, for example, Japanese Patent Publication No.
For example, a refrigerating chuck method as disclosed in Japanese Patent Application Publication No. -40131 and Japanese Utility Model Application Laid-Open No. 1-74034 is used, or a refrigerant gas such as Freon gas is directly sprayed on an object to be engraved on a work table. Means have been proposed.

In the freeze chuck method disclosed in the above Japanese Patent Publication No. 62-40131, the work (object to be engraved) to be fixed is housed in the cavity of the freezing frame, and after cooling this to below the freezing temperature of the liquid. A means for injecting a liquid into the cavity and solidifying the liquid to fix the work is adopted.

In the freeze chuck disclosed in Japanese Utility Model Laid-Open No. 1-74034, a cooling medium is passed through the inside of a freeze chuck having a recess for containing an object to be engraved and a liquid. It is designed to freeze and fix the object to be engraved.

[0007]

However, Japanese Patent Publication No. 62-40131 and Japanese Utility Model Publication No. 1-740.
In the freezing chuck method as disclosed in Japanese Patent Publication No. 34-34, a large freezer for cooling the cavity of the freezing frame is required, and a refrigerating device or piping equipment for circulating a cooling medium is required. However, there was a problem that the equipment cost had to be expensive.

Further, in the means for directly blowing the refrigerant gas such as Freon gas to the object to be engraved, the running cost becomes expensive because the refrigerant gas is consumed in a large amount, and the cost is reduced in a certain cycle. When spraying the refrigerant gas, the temperature of the object to be engraved may change during engraving, and it becomes difficult to control the temperature.Furthermore, when CFC gas is used as the refrigerant gas,
It has been pointed out that problems such as causing environmental damage due to the large amount of CFCs released into the atmosphere.

The present invention has been made in view of the above-mentioned various problems of the prior art. The object of the present invention is not to increase equipment costs and running costs, but also to cause environmental damage. Without encouraging, it is possible to cool the engraving object to a constant temperature, which allows the engraving object to be hardened and fixed in a stable manner. Prevent
An object of the present invention is to provide a control device of an engraving machine that can surely perform engraving processing of a preset shape.

[0010]

In order to achieve the above-mentioned object, a control device for an engraving machine according to the present invention comprises a base, a table arranged on the upper surface of the base, and a column standing upright from the base. Portion and a spindle head mounted on the column portion, and an engraving machine main body portion in which the spindle head can be moved relative to the table in up, down, front, back, left, and right directions, and on the upper surface of the table. A controller for an engraving machine having a cooling vice that is arranged and that cures an object to be engraved by a cooling means by a thermoelectronic element and fixes the engraved object in a cured state. First storage means for storing the relationship between the parameter value and the optimum temperature of the object to be engraved at the parameter value, and second storage means for storing the currently set parameter value of the main body of the engraving machine. Detecting means for detecting the temperature of the object to be engraved, reading means for reading the optimum temperature of the object to be engraved in the parameter values stored in the second storage means from the first storage means, and the reading means Comparing means for comparing the temperature read by the reading means with the temperature detected by the detecting means, and cooling means for making the temperature equal to the temperature read by the reading means based on the comparison result of the comparing means. And a control means for controlling.

[0011]

A cooling vise for hardening and fixing an object to be engraved, such as rubber or thermoplastic resin, by a cooling means is provided on the upper surface of a moving table of the engraving machine, and a spindle attached to the spindle head of the engraving machine. A predetermined engraving process is performed on the object to be engraved, which is fixed to the work table of the cooling vise, by a head engraving cutter or a drill.

Therefore, even when engraving an object to be engraved such as rubber or a thermoplastic resin which is easily deformed, the object to be engraved can be hardened and fixed on the work table of the cooling vise. Alternatively, even if a drill or the like comes into contact with the object to be engraved, the object to be engraved is prevented from being deformed, so that the object to be engraved can be surely engraved into a preset shape.

Then, the comparing means compares the temperature read by the reading means from the first storing means with the temperature detected by the detecting means based on the parameter value stored in the second storing means. , The control means controls the cooling means to be equal to the temperature read by the reading means based on the comparison result,
The cooling means can be controlled so that the temperature is always optimum.

That is, since the object to be engraved placed on the work table of the cooling vise is hardened and fixed at an appropriate temperature according to the material of the object to be engraved and the operation of the main body of the engraving machine, the engraving cutter or By using a drill or the like, it becomes possible to surely perform engraving processing into a desired shape set in advance.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a control device for an engraving machine according to the present invention will be described below in detail with reference to the drawings.

FIG. 1 is an overall perspective view showing the appearance of an engraving machine equipped with a control device for an engraving machine according to the present invention, and FIG.
It is sectional drawing which shows the principal part by the side of the engraving machine shown in FIG. 1, FIG. 3 is sectional drawing which shows the principal part by the side of the front of the engraving machine shown in FIG. 1, and FIG. It is an exploded perspective view of a cooling vise.

The engraving machine is composed of a main body 10 and a cooling vise 20, and the main body 10 is mounted on the base 12, a support 14 provided upright from the base 12, and a support 14 so as to be vertically movable. The main spindle head portion 16 and the moving table 18 integrally installed on the upper surface of the base 12 so as to be movable back and forth and right and left of the main body portion 10.

On the upper surface of the moving table 18, the object to be engraved A
Cooling vise 20 for fixing the cooling means by a cooling means using a thermoelectronic element
Is fixed and the cooling vise 20 is attached by the engraving cutter 22a of the spindle head 22 attached to the spindle head portion 16.
A predetermined engraving process is performed on the object A to be engraved such as rubber fixed to the.

A main spindle head drive motor 24 and a vertical main spindle feed screw 26 rotatably driven by the main spindle head drive motor 24 are installed on the column 14 of the main body 10. By the rotation of 24,
The spindle head portion 16 engaged with the spindle feed screw 26 can be moved up and down.

The spindle head 22 mounted in the spindle head portion 16 is driven by a spindle drive motor 28 to drive a belt 30.
It is rotationally driven via.

A Y-axis feed screw 32 is installed in the base 12, and the Y-axis feed screw 32 is engaged with a moving table 18 installed on the upper surface of the base 12 to allow the Y-axis feed screw 32 to move. A table Y-axis drive motor 36 is connected to the end portion. Then, when the Y-axis feed screw 32 is rotationally driven by the table Y-axis drive motor 36 installed on the column portion 14, the moving table 18 can be moved in the front-back direction of the main body portion 10.

An X-axis feed screw 38 is installed in the moving table 18, and a table X-axis drive motor 40 is installed at the end of the X-axis feed screw 36. When the shaft drive motor 40 is rotationally driven, the moving table 18 can be moved in the left-right direction of the main body 10.

Further, on the upper surface of the moving table 18, a dovetail-shaped concave groove 34 having a wide bottom surface is formed at the center of the moving table 18 in the longitudinal direction, and is fitted into the concave groove 34. The cooling vise 20 is fixed to a predetermined position of the moving table 18 by the bolts (not shown).

Rotational drive control of the spindle head drive motor 24, the spindle drive motor 28, the table Y-axis drive motor 36, and the table X-axis drive motor 40 (hereinafter collectively referred to as the drive motor group 112) is performed. As will be described later based on the block diagram of the control device of the engraving machine shown in FIG. 5, the control unit 100 controls the control.

The base section 12 of the main body section 10 is provided with an operating section 90. By operating each operating section of the operating section 90, the drive motor group 1 is set as an engraving condition.
Parameter values of parameters for controlling 12 operations (moving direction and moving speed of the moving table 18, rotation speed of the spindle head 22, etc.) can be set.

In addition to the parameters for controlling the operation of the drive motor group 112 described above, the manipulator unit 90 also has parameters used exclusively for temperature control, which will be described later, as the material of the object A to be engraved and the engraving object. Information indicating the material and diameter of the cutting cutter 22a can be input.

The cooling vise 20 fixed to the upper surface of the moving table 18 is constructed as shown in the exploded perspective view of FIG.

The cooling vise 20 is, for example, a work table 42.
The engraving object A such as rubber or thermoplastic resin is cooled and hardened and fixed on the upper surface of the cooling vice 2.
0 is installed on the moving table 18 of the main body unit 10, and the engraving target A is engraved by the engraving cutter 22a installed on the spindle head unit 16.

The cooling vice 20 is composed of a work table 42 on which the above-mentioned object A to be engraved is placed, and a thermoelectric element (hereinafter, referred to as a Peltier effect) which adheres to the lower surface of the work table 42 and cools the work table 42. (Referred to as Peltier element) 44, a heat insulating holding plate 46 that holds the periphery of the Peltier element 44, a heat dissipation support plate 48 that radiates heat generated on the lower surface of the Peltier element 44 to the outside, and a lower surface of the heat dissipation support plate 48. A heat dissipation box 50 that is installed to radiate the heat of the heat dissipation support plate 48 to the outside.
And an intake fan 52 that is installed on the left and right sides of the heat dissipation box 50 and that injects cool air from the outside into the heat dissipation box 50, and an exhaust fan 54 that discharges warm air from the inside of the heat dissipation box 50 to the outside. ing.

The work table 42 is formed of an aluminum plate having good thermal conductivity, and has a recess 42a on the upper surface thereof on which the object A to be engraved is placed. The upper and lower surfaces of the recess 42a are processed to be smooth in order to improve the adhesion with the Peltier element 44 and the object A to be engraved. The upper surface of the recess 42a, to which the object A to be engraved is fixed, may be provided with a grid-like groove or a grid-like protrusion having a low height in order to prevent the object A from being displaced. .

The Peltier element 44 has a heat absorbing plate 56 on the upper surface side.
A large number of semiconductor elements 60 whose upper and lower sides are sandwiched by conductors are assembled between the heat sink 58 and the lower surface side heat sink 58, and a current is passed through the semiconductor elements 60 through the lead wires 62, so that the heat sink 56 and the heat sink 56 are radiated. A temperature difference is generated between the plate 58 and the plate 58.

Then, by utilizing the temperature difference between the heat absorbing plate 56 and the heat radiating plate 58, the heat absorbing plate 56 on the upper surface is placed on the work table 4.
2 and the heat dissipation plate 58 is closely adhered to the lower surface of the heat dissipation plate 58 to forcibly release the heat on the side of the heat dissipation support plate 48 to the outside, thereby stabilizing the surface of the work table 42 at a stable cooling temperature. Can be held in.

The heat insulating holding plate 46 for holding the periphery of the Peltier element 44 is formed of a ceramic material or the like having the same thickness as the Peltier element 44.
The opening window portion 6 in which the Peltier element 44 is fitted in the center portion of the
4 are formed. Further, the side wall surface of the heat insulating holding plate 46 is provided with lead wire holes 66 into which the lead wires 62 for energizing the Peltier element 44 are inserted, and the four corners of the heat insulating holding plate 46 have a lower surface. Heat dissipation support plate 4
Bolt holes 68 for inserting bolts for fixing on
Are provided.

The heat radiation support plate 48 is formed of an aluminum material having good heat conductivity, and also serves as the upper lid of the heat radiation box 50 attached to the lower side. Then, a screw hole 80 to which the bolt inserted in the bolt hole 68 of the heat insulation holding plate 46 is fixed, and a bolt hole 82 for inserting a bolt for fixing to the lower heat radiation box 50 are drilled. It is set up.

The heat dissipation box 50 is composed of a heat dissipation support plate 48 which also serves as an upper lid, and a pair of left and right side plates 84 formed of an aluminum material having good heat conductivity. A large number of heat radiation fins 86 are integrally formed.

Intake fan 52 and exhaust fan 54
Are each made up of an axial fan, and are installed at the left and right open ends of the heat dissipation box 50.

A temperature sensor 92 is attached to the upper surface of the end of the work table 42 so that the temperature of the object A to be heat-balanced with the work table 42 can be detected.

Next, an example of a method of assembling the cooling vise 20 will be described. First, the heat dissipation support plate 48 is fixed to the upper surfaces of the pair of left and right side plates 84, and the heat dissipation box 50 is assembled. Then, to the left and right of this heat dissipation box 50,
An intake fan 52 and an exhaust fan 54 are installed.
Then, on the upper surface of the heat dissipation support plate 48, the Peltier element 44
The heat insulating holding plate 46 assembled with is fixed, and the work table 42 is further fixed on the upper surface of the heat insulating holding plate 46, whereby the cooling vice 20 is assembled.

Here, between the contact surfaces of the above-mentioned constituent members,
Applying silicone grease with good thermal conductivity or sandwiching a silicone sheet to fasten each component to improve the adhesion of each component and to reduce the heat between each component. Improves conductivity.

A case where the object A to be engraved is fixed to the work table 42 by using the cooling vise 20 in the above structure will be described.

First, after the object A to be engraved is placed on the upper surface of the concave portion 42a of the work table 42, when the Peltier element 44 is energized, the temperature difference between the heat absorbing plate 56 on the upper surface and the heat radiating plate 58 on the lower surface. Occurs, the heat absorbing plate 56 side is rapidly cooled, and the heat radiating plate 58 side becomes hot.

Therefore, the work table 42, which is in close contact with the upper surface of the heat absorbing plate 56, is cooled, so that the work table 4
The object A to be engraved on the second recess 42a is frozen and hardened, and the water vapor in the atmosphere is frozen. Therefore, the periphery of the object A to be engraved is frozen, and the object A to be engraved is integrally fixed to the work table 42. It should be noted that if water is injected into the recess 42a in advance, the injected water freezes and freezes the periphery of the object A to be engraved, so that the object A to be engraved can be more firmly fixed to the work table 12. it can.

When the Peltier element 44 is energized,
The heat radiation plate 58 side becomes hot, and this heat is conducted to the heat radiation box 50 through the heat radiation support plate 48. At this time, the heat radiation box 50 is set by the intake fan 52 and the exhaust fan 54 installed at the left and right ends of the heat radiation box 50.
Since the cooling air is introduced into the inside and the hot air inside is forcibly released to the outside, the heat of the heat dissipation plate 28 can be efficiently dissipated.

Therefore, the heat absorbing plate 5 of the Peltier element 44 is
A stable temperature difference is always maintained between the heat sink 6 and the heat dissipation plate 58, and the engraving object A can be hardened while the cooling temperature of the engraving object A on the work table 42 is always constant. At the same time, since it can be fixed to the work table 42,
The object A to be deformed, such as rubber or thermoplastic resin,
The engraving cutter 22a of the spindle head 22 can surely engrave a preset shape.

The Peltier element 44 can cool the object A to be engraved to about "-40.degree. C.", and the maximum temperature difference between the heat absorbing plate 56 and the heat radiating plate 58 is "8".
0 ° C ”.

Next, with reference to the block diagram of FIG. 5 and the flowchart of FIG. 6, the control device of the engraving machine, which is the subject matter of the present invention, will be described.

As described above, FIG. 5 is a block diagram of the control device of the engraving machine according to the present invention. The engraving machine controls the entire operation of the engraving machine by the central processing unit (control unit 100). The CPU 100a is used for control.

The control unit 100 also includes a read-only memory 100b in which a program for controlling the overall operation of the CPU 100a is stored, and the CPU 100a.
And a random access memory (RAM) 100c as a working area in which various registers necessary for executing the above-mentioned program are set.

Then, the parameter value input from the parameter value input unit 102 for inputting the parameter value of various parameters set by the operation of the operator unit 90 is temporarily stored in the buffer memory 106 via the interface 104. And then input to the control unit 100.

Furthermore, the temperature of the Peltier element 44 detected by the temperature sensor 92 is fed back through the analog / digital converter (A / D) 124 and temporarily stored in the buffer memory 106. Then, the temperature of the Peltier element 44 detected by the temperature sensor 92 is input to the control unit 100.

On the other hand, the control unit 100 is connected to a parameter value-temperature table 108 composed of a ROM or the like.

This parameter value-temperature table 108
Is a table showing the optimum temperature of the engraved object A when engraving the engraved object A based on the parameter values input to the control unit 100.

That is, the parameter value-temperature table 108
Is a table in which the optimum temperature corresponding to the parameter value is stored in advance based on the fuzzy rule, and the optimum temperature corresponding to the parameter value can be obtained by referring to this table.

Therefore, the CPU 100a sets the parameter value--
By reading the temperature table 108, it is possible to determine the optimum temperature of the engraved object A when engraving the engraved object A with the parameter value input by the parameter value input unit 102.

The controller 100 controls the Peltier element 4 detected by the temperature sensor 92 and the optimum temperature thus determined.
4 and the temperature is compared to obtain the difference, and the Peltier device 4
The signal for setting the voltage / current of the Peltier device 44 is passed through the buffer memory 114 and the digital / analog converter (D / A) 116 so that the temperature of No. 4 becomes the optimum temperature obtained from the parameter value-temperature table 108. And outputs it to the adder 118.

Further, the control section 100 controls the operation of the drive motor group 112 via the interface 110 based on the input parameter value. As a result, the moving table 18 and the spindle head 22 are moved.

Further, the operator can arbitrarily set a correction value for the optimum temperature determined by the control section 100 based on the operation of the operator section 90, and the correction value is inputted as the correction value. It is input from the unit 120 to the addition unit 118.

Then, in the addition section 118, the signal for setting the voltage / current of the Peltier element 44 output from the control section 100 and the correction value input from the correction value input section 120 are added, and the Peltier element 44 is added. The voltage / current value to be applied to the is determined, and the voltage / current control unit 122 is controlled so as to be the voltage / current value, and the temperature of the Peltier element 44 is managed.

Next, based on the flowchart of FIG.
The temperature control of the Peltier element 44 will be described in more detail.

First, when the parameter value from the parameter value input unit 102 is read into the control unit 100 (step S602), the control unit 100 refers to the parameter-temperature table 108 and finds the optimum temperature for the read parameter value. Is determined (step S604).

Next, the temperature of the Peltier element 44 detected by the temperature sensor 92 is read by the control unit 100. (Step S606)

Then, the temperature determined in step S604 is compared with the temperature read in step S606 to obtain a value for achieving the temperature determined in step S604 (step S608).

Further, it is judged whether or not the correction value arbitrarily set by the operator is input from the correction value input section 120 (step S610).

If the determination result of the above step S610 is affirmative, that is, if the correction value is input from the correction value input unit 120, the process proceeds to step S612 and the value obtained in step S608 and the correction value of step S610. The voltage / current value supplied to the Peltier element 44 is controlled based on the sum of the values of and.

On the other hand, if the determination result of step S610 is negative, that is, if the correction value is not input from the correction value input unit 120, the process proceeds to step S614, and the Peltier element is calculated based on the value obtained in step S608. 44
Controls the voltage and current value supplied to the.

In the above embodiment, only the temperature of the Peltier element 44 was controlled. However, when the Peltier element 44 cannot follow the temperature designated by the control unit 100, the temperature of the Peltier element 44 is reversed. The optimum parameter value may be read out from the parameter value-temperature table, and the drive motor group 112 may be controlled so that the engraving condition is optimum for the temperature of the Peltier element 44.

Further, in the above embodiment, the engraving machine in which the spindle head 22 moves up and down and the moving table 18 moves back and forth and left and right has been described. The three-dimensional movement may be performed, or conversely, the spindle head 22 may be moved three-dimensionally in the up, down, front, back, left, and right directions. In short, the cutter 22a for engraving and the object A to be engraved need only be relatively movable in the three-dimensional direction, and any configuration may be used to realize this.

Furthermore, in the above-described embodiment, the temperature of the object A to be engraved is detected by the temperature sensor 92 attached to the work table 42. A temperature gauge or the like may be attached to directly detect the temperature of the object A to be engraved.

[0069]

Since the present invention is constructed as described above, it has the following effects.

A base, a table arranged on the upper surface of the base, a column portion standing upright from the base, and a spindle head mounted on the column portion are provided. The head is arranged on the upper surface of the table, and the engraving machine main body is arranged so that the head can move up and down, front and back, and left and right, and the object to be engraved is hardened by the cooling means by the thermoelectric element and fixed in the hardened state. A controller for an engraving machine having a cooling vise, the first memory storing a relationship between a parameter value of a parameter for operating the main body of the engraving machine and an optimum temperature of an object to be engraved at the parameter value. Means, a second storage means for storing the currently set parameter value of the main body of the engraving machine, a detection means for detecting the temperature of the object to be engraved, and a parameter stored in the second storage means. The optimum temperature of the sculpture in the data value, reading means for reading from said first storage means,
Based on the comparison result of the comparing means for comparing the temperature read by the reading means with the temperature detected by the detecting means, the temperature read by the reading means becomes equal to the temperature. Since it has a control means for controlling the cooling means, it becomes possible to perform engraving processing while the object to be engraved is cooled and hardened, so that the object to be engraved is deformed during the engraving process. It is possible to surely perform engraving processing on a preset shape.

Moreover, the comparing means compares the temperature read by the reading means from the first storing means with the temperature detected by the detecting means on the basis of the parameter value stored in the second storing means. , The control means controls the cooling means to be equal to the temperature read by the reading means based on the comparison result,
The cooling means can be controlled so that the temperature is always optimum.

[Brief description of drawings]

FIG. 1 is an overall perspective view showing an appearance of an engraving machine provided with a control device for an engraving machine according to the present invention.

FIG. 2 is a cross-sectional view showing a main part on a side surface side of the engraving machine of FIG.

3 is a cross-sectional view showing a main part on the front side of the engraving machine of FIG.

FIG. 4 is an exploded perspective view of a cooling vise.

FIG. 5 is a block diagram showing a control device of an engraving machine according to an embodiment of the present invention.

FIG. 6 is a flowchart showing temperature control of a Peltier element.

[Explanation of symbols]

 10 Engraving machine 12 Base 14 Strut part 16 Spindle head part 18 Moving table 20 Cooling vice 22 Spindle head 44 Peltier element 90 Operator part 92 Temperature sensor 100 Control part 102 Parameter value input part 108 Parameter value-Temperature table 112 Drive motor group 120 Correction value input unit 122 Voltage / current control unit

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Enlarged Ichikawa 1227 Okubocho, Hamamatsu City, Shizuoka Prefecture Roland Dee. Gee. Incorporated (72) Inventor Several Miyamoto 1227 Okubocho, Hamamatsu City, Shizuoka Prefecture Roland Dee. Gee. Within the corporation

Claims (1)

[Claims] 1. A base, a table disposed on an upper surface of the base, a column portion standing upright from the base, and a spindle head mounted on the column portion. The main body of the engraving machine is arranged so that the spindle head can move relatively in the vertical and horizontal directions, and is arranged on the upper surface of the table. A controller of an engraving machine having a fixed cooling vise, wherein a relationship between a parameter value of a parameter for the operation of the engraving machine body and an optimum temperature of an object to be engraved at the parameter value is stored. Storage means, second storage means for storing the currently set parameter values of the engraving machine main body, detection means for detecting the temperature of the object to be engraved, and the storage means stored in the second storage means. Reading means for reading the optimum temperature of the object to be engraved in the meter value from the first storage means; and comparing means for comparing the temperature read by the reading means with the temperature detected by the detecting means. A controller for controlling the cooling unit so that the temperature is equal to the temperature read by the reading unit based on the comparison result of the comparison unit.