JP2008023658A - Machine tool - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce the heat displacement of a structure, and to improve working precision by mitigating the temperature variation of a heating medium with respect to a control target temperature. <P>SOLUTION: This electric discharge working device 1 having a base 2 being a base part, a column 3 erected on the base 2, a working head 4 provided on the column 3 and installed with a tool electrode E to work a work W on it, and a work holding unit 5 to arrange the work W on it as a structure, is provided with a heat exchanging plate 20 including a channel 21c to make a cooling medium flow and installed on the outer peripheral surface of the base, and the column and a cooling medium temperature control device 50 to control a temperature of the cooling medium to control a target temperature. The heat exchanging plate 20 includes a constitution interposing a heat conduction impingement plate 22 between the channel 21c to make the cooling medium flow and the outer peripheral surface of the base and the column. <P>COPYRIGHT: (C)2008,JPO&amp;INPIT

Description

  The present invention relates to a machine tool having a configuration capable of reducing thermal displacement generated in a structure by a heat medium controlled to a predetermined control target temperature.

  In recent years, machining with machine tools often requires ultra-precise machining on the order of several tens of nanometers, and unexpected temperature due to changes in temperature in the processing chamber in which the machine tool is installed or contact of the operator with the structure. It is necessary to reduce the displacement (thermal displacement) and to keep the relative positional relationship between the tool and the workpiece constant. For example, Patent Document 1 discloses a configuration for reducing thermal displacement. A machine tool provided is disclosed.

That is, according to the machine tool of the literature 1, a heat insulating material (heat conduction buffer) is affixed to the outer peripheral surface of the bed (base) and the column, and the temperature change due to the surrounding air conditioning environment or the like is caused by this heat insulating material. And a structure that regulates transmission to the column. However, the heat insulating structure of the literature 1 does not have a means for controlling the temperature itself such as a heating means or a cooling means, and even if a slight temperature change due to a change in the surrounding environment can be regulated, for example, the temperature change If the change width is large enough to exceed the allowable limit even for a short time, the temperature after the change may eventually be transferred to the bed or column to cause thermal displacement.

In order to solve such a problem, a machine tool shown in Patent Document 2 is disclosed. That is, according to the machine tool of the literature 2, there is provided means for controlling the temperature by providing a cooling plate in which heat exchange oil (heat medium) is circulated in a column portion provided with a tool and a holding portion for holding a workpiece. It is possible to keep the temperature of the column part and the holding part constant even if the surrounding temperature environment changes. A heat transfer filler (heat transfer cement) is interposed between the cooling plate and the column portion and the holding portion, and heat transfer is actively promoted through the filler.

JP 2003-300122 A JP 2005-262379 A

By the way, in the machine tool of Patent Document 2 described above, if there is a temperature variation in the heat medium itself, this variation is transmitted to the structure and an unexpected temperature displacement (thermal displacement) may occur in the structure. is there. That is, although the heat medium is generally supplied with a constant control target temperature, it is normally controlled with a constant temperature fluctuation range with respect to the control target temperature, and a fluctuation of about 0.1 K is allowable. It is often the case.

In particular, in the above-described machine tool, a heat transfer filler is actively interposed between the cooling plate, the column portion, and the holding portion to promote heat transfer, and the temperature of the heat medium itself. The fluctuation is quickly transmitted to the structure, and thermal displacement occurs in the structure, and the relative positional relationship between the tool and the work fluctuates. As a result, there is a possibility that the machining accuracy may be greatly affected.

To deal with such problems, for example, it is conceivable to construct a control circuit in advance assuming various factors that contribute to the temperature fluctuation of the heat medium, and strictly control the temperature of the heat medium. It is extremely difficult to build a control circuit taking into account all possible factors such as a delay in the transmission of temperature fluctuations to the machine, etc., and the control circuit becomes complicated and the production period becomes longer. There is also a risk that the manufacturing cost of the device will increase.

The present invention has been made in view of such circumstances, and provides a machine tool capable of reducing the thermal displacement of the structure and improving the machining accuracy by buffering the temperature fluctuation with respect to the control target temperature of the heat medium. With the goal.

In order to achieve the above-mentioned object, the invention of claim 1 includes, as a structure, a base that forms a base, a column that is erected on the base, and a machining head that is provided on the column and on which a tool for machining a workpiece is mounted. A heat exchange plate mounted on an outer peripheral surface of at least one of the base and the column, and a temperature of the heat medium. A heat medium temperature control means for controlling the heat medium to a control target temperature, and the heat exchange plate has a heat conduction buffer between the flow path through which the heat medium flows and the outer peripheral surface of at least one of the base and the column. It is characterized by including an intervening structure.

According to the present invention, since the heat medium temperature control means for controlling the temperature of the heat medium to the control target temperature is provided, even when the temperature change width of the surrounding environment is large, the base of the machine tool and the column At least one of the temperatures can be kept constant, and the heat exchange plate further includes a heat conduction buffer between the flow path through which the heat medium flows and the outer peripheral surface of at least one of the base and the column. Since the intervening configuration is included, even when the temperature of the heat medium fluctuates with respect to the control target temperature, the heat conduction buffer acts to buffer the temperature fluctuation of the heat medium, thereby It can be transmitted to at least one of them.

The temperature of the heat medium is controlled within a certain temperature fluctuation range and within a certain temperature fluctuation period with respect to the control target temperature by the heat medium temperature control means, and the temperature fluctuation width is controlled by the heat conduction buffer. When buffered within the regulation range and transmitted to at least one of the base and the column, the temperature variation pattern of the heat medium, the control target temperature, the maximum width of the temperature variation range, the longest cycle of the temperature variation period, The heat medium temperature control time by the heat medium temperature control means is specified as an arithmetic expression using the parameters as parameters, and the thickness of the heat conduction buffer is determined as the control target temperature, the maximum temperature fluctuation width, and the longest temperature fluctuation cycle. Temperature variation of the heat medium identified based on the period, temperature control time, target regulation width, heat conductivity of the heat transfer buffer, specific heat of the heat transfer buffer, and density of the heat transfer buffer Pattern If it is set by analysis using the formula and Fourier's law, it will be within the desired target regulation range for the temperature variation of the heat medium depending on the performance of the heat medium temperature control means and the material of the heat conduction buffer. Thus, the thickness of the heat conduction buffer can be set easily. Since the temperature variation pattern is set based on the maximum temperature variation width and the longest temperature variation cycle, the thickness of the heat conduction buffer can be set on the safe side. (Claim 2).

Further, if the heat conduction buffer is made of a vinyl chloride material, the heat conductivity of the vinyl chloride material is reduced while the thickness of the heat conduction buffer is set small due to the relatively low thermal conductivity of the vinyl chloride material. Therefore, it is possible to reduce the temperature variation of the machine tool within a desired range, thereby contributing to weight reduction and compactness of the machine tool.

The structure of the machine tool has a heating element inside, and if a heat exchange plate is further mounted on the inner surface of the structure facing the heating element, the structure of the machine tool has a heating element such as a motor. Even in this case, the heat exchange plate mounted on the inner surface of the structure can act to prevent the heat generated by the heating element from being transmitted to the structure, and the temperature variation of the heat medium can be buffered. .

In addition, a cover is provided to cover the outer peripheral surface with a certain distance from the outer peripheral surface of the base, column, and machining head, and the machine tool is stored in the chamber, and between the outer peripheral surface and the cover and in the chamber. If air set to a constant temperature is supplied, the machine tool temperature is further ensured.

Furthermore, it is more preferable to have feed means for changing the relative positional relationship between the workpiece and the tool, and to supply air set at a constant temperature to the feed hydrostatic bearing portion of the feed means.

ADVANTAGE OF THE INVENTION According to this invention, the thermal displacement of a structure can be reduced by buffering the temperature fluctuation with respect to the control target temperature of a heat medium, and the processing precision of a machine tool can be improved.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a block diagram showing an outline of an electric discharge machining apparatus (machine tool) showing a first embodiment of the present invention. The outline of the electric discharge machining apparatus will be described with reference to FIG. 1. The electric discharge machining apparatus 1 is erected on the base 2 constituting the base of the apparatus 1 and the rear upper surface of the base 2 and includes an inclined surface at an upper portion thereof. The column 3 that is bent 90 ° and extends slightly forward is attached to the front surface of the extending portion 3 a of the column 3, and extends downward, and at a substantially intermediate position of the electric discharge machining apparatus 1, the tool electrode E (tool) Are mounted on the front surface of the base 2 and the workpiece holding unit 5 is disposed so as to face the tool electrode E, the processing tank 6 is immersed in the machining liquid, and the workpiece holding unit. 5 and a work table 7 on which the processing tank 6 is placed.

A cover 8 is provided around the base 2, the column 3, and the machining head 4 with a certain distance from the outer peripheral surface of the base 2 and the like. An outer peripheral surface of the base 2 and the column 3 (hereinafter simply referred to as the column 3 or the like) in a space formed between the outer peripheral surface of the base 2 and the column 3 and the cover 8 will be described in detail later. A heat exchange plate 20 is attached. The entire electric discharge machining apparatus 1 is accommodated in the chamber 9.

A Z-axis motor 10z is accommodated in the machining head 4, and an X-axis motor 10x and a Y-axis motor 10y are accommodated in the work table 7, and these axis motors 10x to 10z (feed means) are controlled. Thus, the relative positional relationship between the tool electrode E and the workpiece W can be set as appropriate.

An air supply unit 40 provided with an air temperature control device 30 and a cooling medium supply unit 60 provided with a cooling medium temperature control device (heat medium temperature control means) 50 are provided outside the chamber 9. That is, in the chamber 9, a space formed between the cover 8, the base 2, the column 3, and the outer peripheral surface of the processing head 4, where the air set at a constant temperature by the air temperature control device 30 and the air supply unit 40 Furthermore, the X-axis, Y-axis, and Z-axis feed hydrostatic bearings (not shown) are continuously supplied, and the electric discharge machining apparatus 1 is maintained at a constant temperature without being affected by the external temperature environment. It is comprised so that.

Then, the cooling medium (heat medium) controlled at a constant control target temperature by the cooling medium temperature control device 50 and the cooling medium supply unit 60 is continuously supplied to the heat exchange plate 20, thereby allowing the outside air to enter the chamber 9. Even when the operator inflows or the operator touches the cover 8 during maintenance work or the like, the temperature uniformity of the electric discharge machining apparatus 1 is further secured. Note that a cooling pipe (not shown) is wound around each of the shaft motors 10x, 10y, and 10z, and the cooling pipe is also controlled to a constant control target temperature by the cooling medium temperature control device 50 and the cooling medium supply unit 60. Since the cooling medium is supplied, the temperatures of the shaft motors 10x, 10y, and 10z are kept constant.

The heat exchange plate 20 is composed of a tube member 21 and a heat conduction buffer plate (heat conduction buffer) 22 as shown in FIG. 2 and FIG.
The pipe member 21 has a meandering shape including a plurality of straight pipe portions 21a and a curved pipe portion 21b connecting one end portions of the adjacent straight pipe portions 21a, and the pipe member 21 has a circular cross section inside. It has a hollow part. This hollow portion functions as a flow path 21c for circulating the cooling medium. In addition, oil, water, air etc. are employable as a cooling medium, for example.

The heat conduction buffer plate 22 is formed in a flat plate shape. The surface 22a of the heat conduction buffer plate 22 functions as a mounting surface for the tube member 21, and the back surface 22b functions as a cooling surface for the column 3 and the like. It is mounted on the column 3 or the like so as to be interposed between the 3 and the like.

That is, the pipe attachment 22c is provided on the surface side 22a of the heat conduction buffer plate 22, and the pipe member 21 can be attached to the surface side 22a by the pipe attachment 22c. The back surface side 22b of the heat conduction buffer plate 22 is in contact with the column 3 or the like, and heat exchange is performed between the cooling medium flowing through the flow path 21c of the tube member 21 and the column 3 or the like via the back surface side 22b. It is the composition that is called.

Therefore, even if a change occurs in the surrounding temperature environment, the heat exchange plate 20 acts to buffer this temperature change, and the temperature of the column 3 and the like can be kept constant. Since the heat conduction buffer plate 22 is interposed between the flow path 21c for circulating the medium and the column 3 or the like, even when the temperature of the cooling medium varies with respect to the control target temperature, This temperature fluctuation can be buffered and transmitted to the column 3 or the like. The heat conduction buffer plate 22 is attached to the column 3 or the like by a fastener such as an adhesive or a bolt.

As a constituent material of the heat conduction buffer plate 22, plastic materials having relatively low thermal conductivity, more specifically, general-purpose plastics such as polyvinyl chloride and polyethylene, polyamide, polyacetal, polyphenylene sulfide, etc. Plastics are preferable, and in particular, a vinyl chloride material represented by polyvinyl chloride (vinyl chloride resin) is more preferable because it can be procured inexpensively and easily. Even if the material has a relatively high thermal conductivity such as a ceramic or iron-based material, the temperature variation of the cooling medium can be set within a desired range by appropriately setting the thickness of the heat conduction buffer plate 22. Various materials that can be buffered can be employed.

As illustrated in FIG. 4, the cooling medium temperature control device 50 includes a control target temperature input unit 51, a cooling medium temperature comparison unit 52, and a cooling medium temperature command output unit 53. That is, as shown in FIG. 5, each of these units functions mutually to control the temperature of the cooling medium within a certain temperature fluctuation range with respect to the control target temperature and within a certain temperature fluctuation period. In this embodiment, when the control target temperature is set to 296.15 K (23 ° C.), the cooling medium temperature control device 50 cools the temperature fluctuation range within 0.1 K and the temperature fluctuation period within 1 s. It has the ability to control the temperature of the medium.

The control target temperature input unit 51 has a function of inputting the control target temperature of the cooling medium by keyboard operation, volume operation, touch panel operation, or the like, and outputting the input control target temperature to the cooling medium temperature comparison unit 52. Have.
The cooling medium temperature comparison unit 52 receives the control target temperature from the control target temperature input unit 51 and the temperature of the cooling medium from a temperature detector 52a provided on the cooling medium supply path. The temperature comparison unit 52 has a function of calculating the temperature difference and outputting the temperature difference to the coolant temperature command output unit 53 together with the control target temperature.

The cooling medium temperature command output unit 53 receives the control target temperature and the difference between the control target temperature and the detected temperature of the cooling medium from the cooling medium temperature comparison unit 52, and based on the control target temperature and the temperature difference. And a function of outputting a control signal to the cooling medium supply unit 60.

Next, a method for setting the thickness of the heat conduction buffer plate 22 will be described in order to buffer the temperature fluctuation of the cooling medium within the intended target regulation range and transmit it to the column 3 or the like.
That is, the thickness of the heat conduction buffer plate 22 includes the control target temperature, the maximum temperature fluctuation width, the longest temperature fluctuation period, the temperature control time of the cooling medium by the cooling medium temperature control device 50, and the heat conduction buffer. The cooling medium based on the target regulation width for the temperature variation of the cooling medium due to the action of the plate 22, the thermal conductivity of the heat conduction buffer plate 22, the specific heat of the heat conduction buffer plate 22, and the density of the heat conduction buffer plate 22. The temperature variation pattern can be set by an analysis using an arithmetic expression and Fourier law.

More specifically, the thickness of the heat conduction buffer plate 22 is calculated as unsteady heat conduction because the temperature of the cooling medium fluctuates with respect to the control target temperature. From the Fourier law, It can be calculated and set by a forward differential type differential equation.

と右側から入る熱量

の和であり、

となる。
この熱量Δｑ_ｎを受けとることにより要素ｎの温度Ｔ_ｎはＴ_ｎ＋ΔＴ_ｎに変化し、この変化分ΔＴ_ｎは、熱伝導緩衝板２２の比熱をｃｐ、密度をρとして数４に示す熱容量Ｃ

に反比例し、

となるため数３乃至数５より

となる。 As shown in FIGS. 6A to 6D, the heat conduction buffer plate 22 interposed between the tube member 21 and the column 3 or the like is considered as a rectangular parallelepiped element divided into N in the heat transfer direction (tube). The element number closest to the member 21 is 0, the element numbers are 1,..., N−1, n, n + 1,... And the element number closest to the column 3 is N−1). At this time, heat input / output of each element is as shown in FIGS. The width of each element is a, the area of the surfaces in contact with each other is A, the temperature of a certain element n is Tn, the temperature of the element n-1 on the left side of the element n is T _n-1 , and the element n + 1 on the right side is _{Let Tn + 1} . The amount of heat Δq _n entering the element n during the time Δt (hereinafter referred to as the calculation unit time) is the amount of heat entering from the left side with the thermal conductivity k.

And the amount of heat entering from the right side

Is the sum of

It becomes.
By receiving this amount of heat Δq _n , the temperature T _n of the element n changes to T _n + ΔT _n , and this change ΔT _n is the heat capacity C shown in Equation 4 where cp is the specific heat of the heat conduction buffer plate 22 and ρ is the density.

Inversely proportional to

From Equation 3 to Equation 5

It becomes.

となる（図６（ｂ））。 That is, if the temperature of the element n at the temperature control time t of the cooling medium by the cooling medium temperature control device 50 is newly defined as T _{n, t} , the temperature T _{n, t + Δt} at the temperature control time t + Δt after _Δt is

(FIG. 6B).

Ｔｂａｓｅ：冷却媒体の制御目標温度［Ｋ］
Ｔｒａｎｇｅ：冷却媒体の温度変動幅の最大幅［Ｋ］
Ｂ：冷却媒体の温度変動周期の最長周期［ｓ］
ｔ：冷却媒体温度制御装置５０による冷却媒体の温度制御時間［ｓ］
とすると、Ｔｐ，ｔは要素番号―１の温度Ｔ_−１，ｔに相当するから、管部材２１に最も近い要素０の温度Ｔ_{０，ｔ＋Δｔ} は、

となる（図６（ｃ））。また、最もコラム３等に近い要素Ｎ−１の温度Ｔ_{Ｎ−１，ｔ＋Δｔ} は、安全側を考慮してコラム３等に逃げる熱がないとすると、数２においてΔｑ_ｎｒ＝０となるから、

となる（図６（ｄ））。 Further, the temperature of the pipe member 21 is, for example, the cooling medium temperature Tp, t shown in Formula 8 (the arithmetic expression of the temperature variation pattern of the cooling medium).

Tbase: Control target temperature of the cooling medium [K]
Range: Maximum width of temperature variation of the cooling medium [K]
B: Longest cycle [s] of the temperature variation cycle of the cooling medium
t: cooling medium temperature control time [s] by the cooling medium temperature control device 50
Then, since Tp, t corresponds to the temperature T- _{1, t} of the element number -1, the temperature T0 _{, t + Δt} of the element 0 closest to the pipe member 21 is

(FIG. 6C). Further, the temperature T _{N−1, t + Δt} of the element N−1 closest to the column 3 or the like is Δq _nr = 0 in Equation 2 if there is no heat escaping to the column 3 or the like in consideration of the safety side.

(FIG. 6D).

となるΔｔを用いる必要がある。 As a stability condition for this simulation,

It is necessary to use Δt.

From the above equation, the temperature of each element is repeatedly calculated in units of the calculation unit time Δt, so that the temperature relative to the control target temperature Tbase of the element N-1 (the back surface side 22b of the heat conduction buffer plate 22) closest to the column 3 etc. The fluctuation range (= _{TN-1, t + Δt−} Tbase) is obtained, and the thickness of the heat conduction buffer plate 22 can be set so that the temperature fluctuation range is within the target regulation range.

Next, calculation examples based on such a calculation method will be described with reference to Table 1, FIG. 5, and FIG. That is, in the cooling medium temperature control device 50 of the present embodiment having the performance shown in FIG. 5, when the control target temperature Tbase of the cooling medium is set to 296.15 K (23.0 ° C.), the maximum width of the temperature fluctuation range The transition is 0.1 K, the longest period B of the temperature fluctuation period is 1 s, and Tp, t calculated based on Equation 8, that is, the temperature fluctuation pattern of the cooling medium is specified as shown in FIG.

Subsequently, the material of the heat conduction buffer plate 22 is polyvinyl chloride, and the heat conductivity k of the heat conduction buffer plate 22 is 0.16 [J / (m · s · K)] and the specific heat cp as shown in Table 1. Is set to 0.95 [J / (kg · K)], the density ρ is set to 1400 [kg / m ³ ], the division number N of the heat conduction buffer plate 22 in the heat transfer direction is set to 5, and the calculation unit time Δt Is set to 0.0005 [s], as shown in FIG. 7, the temperature fluctuation width (= _{TN−1, t + Δt−} Tbase) with respect to the control target temperature Tbase on the back surface side 22b of the heat conduction buffer plate 22 is set as the target regulation. In order to buffer within a width of ± 0.01 [K] (backside temperature of heat conduction buffer plate 296.15 K (23.0 ° C.) ± 0.01 K), the thickness N × a of the heat conduction buffer plate 22 is about 18 mm. It turns out that it is necessary to set to. In addition, since the above-mentioned temperature fluctuation pattern is set based on the maximum width of the temperature fluctuation width and the longest period of the temperature fluctuation period, the thickness of the heat conduction buffer plate 22 can be set on the safe side.

Next, a second embodiment to a fourth embodiment of the present invention will be described with reference to FIGS.
2nd Embodiment of this invention has shown the structure which extended the attachment location of the heat exchange plate 20. As shown in FIG. Specifically, as shown in FIG. 8, the heat exchange plate 20 is mounted on the outer peripheral surfaces of the base 2 and the column 3, and is further mounted on the outer peripheral surface of the processing head 4 to cool the processing head 4. Even in this case, the temperature variation of the cooling medium is buffered.

Similarly, the third embodiment of the present invention has a configuration in which the mounting location of the heat exchange plate 20 is expanded, and in the case where a heating element such as the machining head 4 is provided inside the electric discharge machining apparatus, the structure facing the heating element. The structure which attached the heat exchange plate further to the inner surface of is shown. Specifically, as shown in FIG. 9, the Z-axis motor is mounted by mounting the heat exchange plate 20 of the present invention on the inner surface of the machining head 4 facing the Z-axis motor 10z housed in the machining head 4. Even when 10z generates heat, the heat generation is prevented from being transmitted to the machining head 4, and the temperature variation of the cooling medium is also buffered.

4th Embodiment of this invention has shown the structure which changed the structure of the heat exchange plate 20 partially. Specifically, as shown in FIG. 10, a gap 22d is formed between the back surface side 22b of the heat conduction buffer plate 22 and the column 3 or the like, and air is interposed in the gap 22d. By adopting such a configuration, the air interposed in the gap 22d also acts as a heat conduction buffer, so that the thickness of the heat conduction buffer plate 22 can be set small.

It should be noted that the present invention is not limited to the first to fourth embodiments described above, and it is needless to say that various application implementations or modifications can be made as necessary. For example, in the present embodiment, a single material is adopted for the heat conduction buffer plate 22 of the heat exchange plate 20, but a configuration in which a plurality of materials are combined may be used. As for the tool 22c, various heat conduction buffers such as a vinyl chloride material may be used. Furthermore, although the thickness of the heat conduction buffer plate 22 is set by calculation, the temperature of the front surface side 22a and the back surface side 22b of the heat conduction buffer plate 22 may be set by actual measurement. Furthermore, although the column 3 and the like are cooled by the cooling medium, a heating medium may be employed as necessary for heating.

  The present invention can be used for machine tools. Specifically, it is useful when the temperature of the heat medium fluctuates with respect to the control target temperature in a machine tool having a configuration that reduces the thermal displacement generated in the structure by the heat medium.

It is a figure which shows the structure of the electric discharge machining apparatus which concerns on 1st Embodiment of this invention. It is a top view which shows the structure of the heat exchange plate with which the electrical discharge machining apparatus is mounted | worn. It is sectional drawing which shows the structure of the same heat exchange plate. It is a block diagram which shows the structure of a cooling medium temperature control apparatus. It is a schematic diagram for demonstrating the state of the temperature fluctuation in the temperature control of a cooling medium. It is a schematic diagram for demonstrating the thickness setting method of the heat conductive buffer plate of a heat exchange plate. It is a graph which shows an example of the temperature fluctuation pattern of a cooling medium, and the buffer state of the temperature fluctuation in the heat conductive buffer board back surface side. It is a figure which shows the mounting location of the heat exchange plate of the electric discharge machining apparatus which concerns on 2nd Embodiment of this invention. It is a figure which shows the mounting location of the heat exchange plate of the electric discharge machining apparatus which concerns on 3rd Embodiment of this invention. It is sectional drawing which shows the structure of the heat exchange plate of the electric discharge machining apparatus which concerns on 4th Embodiment of this invention.

Explanation of symbols

E: Tool electrode W: Work piece 1: Electric discharge machining device 2: Base 3: Column 3a: Column extension part 4: Work head 5: Work holding unit 6: Work tank 7: Work table 8: Cover 9: Chamber 10: Motor 20: Heat exchange plate 21: Pipe member 21a: Straight pipe portion 21b: Curved pipe portion 21c: Flow path 22: Heat conduction buffer plate 22a: Front side 22b of heat conduction buffer plate: Back side 22c of heat conduction buffer plate: Pipe fitting 22d: Clearance 30: Air temperature control device 40: Air supply unit 50: Cooling medium temperature control device 51: Control target temperature input unit 52: Cooling medium temperature comparison unit 52a: Temperature detector 53: Cooling medium temperature command output Unit 60: Cooling medium supply unit

Claims (3)

The structure includes a base that forms a base, a column that is erected on the base, a machining head that is provided on the column and mounts a tool for machining the workpiece, and a workpiece holding unit that arranges the workpiece. In machine tools,
A heat exchange plate that includes a flow path for circulating a heat medium, and is mounted on an outer peripheral surface of at least one of the base and the column;
A heat medium temperature control means for controlling the temperature of the heat medium to a control target temperature,
The heat exchange plate includes a configuration in which a heat conduction buffer is interposed between a flow path through which the heat medium flows and at least one outer peripheral surface of the base and the column. . The temperature of the heat medium is controlled by the heat medium temperature control means within a constant temperature fluctuation range with respect to the control target temperature and within a constant temperature fluctuation period, and the temperature fluctuation width is controlled by the heat medium temperature control means. In the case of transmitting to at least one of the base and the column by buffering within a target regulation width by a conductive buffer,
The temperature variation pattern of the heat medium is a parameter of the control target temperature, the maximum width of the temperature variation width, the longest period of the temperature variation period, and the temperature control time of the heat medium by the heat medium temperature control means. Specified as
The thickness of the heat conduction buffer includes the control target temperature, the maximum temperature fluctuation width, the longest temperature fluctuation period, the temperature control time, the target regulation width, and the heat conduction buffer. The heat conductivity of the heat transfer buffer, the specific heat of the heat transfer buffer, and the density of the heat transfer buffer are set by the analysis using the arithmetic expression of the temperature variation pattern of the specified heat medium and the Fourier law The machine tool according to claim 1. The machine tool according to claim 1, wherein the heat conduction buffer is made of a vinyl chloride material.

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