WO2008015786A1

WO2008015786A1 - Electric discharge machine and method for correcting thermal displacement of the electric discharge machine

Info

Publication number: WO2008015786A1
Application number: PCT/JP2007/000818
Authority: WO
Inventors: Hiroshi Hanabusa
Original assignee: Sodick Co., Ltd.
Priority date: 2006-08-03
Filing date: 2007-07-31
Publication date: 2008-02-07
Also published as: JP5137172B2; JP2008036739A

Abstract

In an electric discharge machine, it is possible to easily and effectively suppress a relative displacement amount in a predetermined direction without requiring a complicated mechanism. The electric discharge machine (1) generates electric discharge between electrodes (D) of an electrode (6) and a work (W) and performs machining of the work (W) by a discharge energy. The electric discharge machine (1) includes a first portion and a second portion for generating a change in the relative position between the electrode (6) and the work (W) in a predetermined direction. The first portion has a slower thermal response speed in the predetermined direction against the temperature change. An outdoor air of an amount experimentally obtained to minimizes the relative position change in the predetermined direction between the electrode (6) and the work (W)is supplied to the first portion.

Description

Specification

Electric discharge machine and method for correcting thermal displacement of electric discharge machine

Technical field

TECHNICAL FIELD [0001] The present invention relates to an electric discharge machine capable of correcting a thermal displacement of a machine body accompanying a change in temperature of outside air, and a thermal displacement correction method in the electric discharge machine.

Background art

There is known an electric discharge machine that generates an electric discharge between an electrode and a workpiece and processes the workpiece with discharge energy. Since each part of the machine body that forms the EDM is generally different in shape, such as thickness and length, if the EDM is installed in an environment where temperature changes occur, the difference in heat capacity, etc. Due to this, a temperature difference occurs in each part. When this temperature difference occurs, a difference also occurs in the amount of thermal displacement at each of the parts, so that the relative position between the electrode and the workpiece may change and the processing accuracy may decrease. Therefore, conventionally, a method has been disclosed in which outside air is taken into the machine to reduce the temperature difference between the inner wall and the outer wall of the machine body, the temperature of the entire machine is uniform, and the change in the relative position due to thermal displacement is reduced. ing.

[0003] In the above method, a temperature detection sensor is arranged in each part of the machine main body, and rotation of a blower fan attached to the machine main body is performed in order to keep the temperature difference of each part within a specified range. The method of controlling the air flow rate by changing the number (Patent Document 1), and by providing the ribs integrated with these in the column and bed, smooth ventilation is provided inside the column and bed, and the entire main structure There is a method (Patent Document 2) for equalizing the temperature distribution. Furthermore, if it is not sufficient to take outside air into the machine, it is possible to circulate a precisely temperature-controlled gas or liquid inside the machine, or cover the entire EDM machine with a cover and shut it off from the outside air. There are also disclosed methods for avoiding the influence of changes in the outside air temperature.

Patent Document 1: Japanese Patent Application Laid-Open No. 5-177500

Patent Document 2: Japanese Patent Laid-Open No. 2-3 0 8 1 2

Disclosure of the invention Problems to be solved by the invention

[0004] However, the method for controlling the air flow rate as described above and the method for circulating the temperature-controlled gas or liquid inside the machine require a complicated control mechanism, which is costly. The method of covering the entire EDM machine with a cover requires the cost of the cover, and increases the size of the entire machine. In addition, even if the entire machine can be maintained at a uniform temperature by the above method, the temperature of each part of the machine body varies depending on the shape. The time required for the temperature to become equal to the outside air temperature after the change is different, and this time difference may cause variations in the amount of thermal displacement, which may reduce the processing accuracy.

[0005] The present invention has been made in view of such circumstances, and in an electric discharge machine and an electric discharge machine that can easily and effectively suppress the amount of relative displacement in a predetermined direction without having a complicated mechanism. Means for solving a problem with the purpose of providing a thermal displacement correction method

[0006] In order to achieve the above object, one aspect of the present invention relating to an electric discharge machine is to generate an electric discharge between the electrode (6) and the work piece (W) (D), thereby reducing the discharge energy. In the electric discharge machine (1) that processes the workpiece (W) more, the first and second parts that cause a change in the relative position of the electrode (6) and the workpiece (W) in a predetermined direction Among them, in the first part where the thermal response speed in the predetermined direction with respect to the temperature change is slow, the relative relationship in the predetermined direction between the electrode (6) and the work piece (W) accompanying the temperature change was experimentally obtained in advance. It is characterized by having an air supply means (2 2, 7 2) for blowing outside air with an air volume that minimizes the change in position.

Here, for example, the electric discharge machine (1) includes a bed (2), a column (3) erected on the rear side of the upper surface of the bed (2), and a front surface of the upper surface of the bed (2). In the case where the table (4) on which the workpiece (W) is placed and placed and the head (5) held by the column (3) and having the electrode (6) mounted thereon are provided, It can be a bed (2) or a column (3). [0008] Another aspect of the present invention relating to an electric discharge machine is that an electric discharge is generated at the gap (D) between the electrode (6) and the workpiece (W), and the workpiece (W) In the electric discharge machine (1) that performs machining, the first and second parts that cause changes in the horizontal relative position of the electrode (6) and the workpiece (W) are affected by temperature changes. In the first part, where the thermal response speed in the horizontal direction is slow, the change in the relative position in the horizontal direction between the electrode (6) and the workpiece (W), which is experimentally determined, is minimized. It is characterized by having a blowing means (22, 72) for blowing outside air of an air volume.

Here, for example, the electric discharge machine (1) includes a bed (2), a column body (7) erected on the rear side of the upper surface of the bed (2), and an upper end surface of the column body (7). A column (3) composed of an upper column (8) placed on the table (4), a table (4) placed on the front side of the upper surface of the bed (2) on which the workpiece (W) is placed, and a table ( 4) When the head (5) is held on the front of the column upper part (8) and the electrode (6) is attached to the lower end so that it is located above the bed (2) And the second part can be the upper column (8) and the head (5).

[0010] Still another aspect of the present invention relating to an electric discharge machine is that an electric discharge is generated between the electrode (6) and the workpiece (W) (D), and the workpiece (W) is generated by the discharge energy. In the electric discharge machine (1) that performs the machining of the first and second parts that cause changes in the relative positions of the electrode (6) and the workpiece (W) in the upward and downward direction, In the first part where the thermal response speed in the vertical direction is slow, the change in the relative position in the vertical direction between the electrode (6) and the workpiece (W) that accompanies the temperature change is experimentally determined in advance. It is characterized by having air blowing means (22, 72) for blowing the outside air of

[0011] Here, for example, the electric discharge machine (1) includes a bed (2), a column body (7) and a column body (7) erected on the rear side of the upper surface of the bed (2). ), The column (3) is composed of the upper part of the column (8), and the table (4) is placed on the front side of the upper surface of the bed (2) on which the workpiece (W) is placed. The tape And the head (5), which is held on the front of the upper part of the column (8) and mounted with the electrode (6) at the lower end so that it is positioned above the column (4). 3) and the second part can be a table (4), a workpiece (W), a head (5), and an electrode (6).

[0012] When the outside air is blown into the first part, a cavity (21, 7 1) through which the outside air is blown is formed, and the outside air blown to the first part is It is more preferable to form openings (23, 73) for discharging air, since the flow of the blown outside air in the interior is improved and the outside temperature is quickly approached.

[0013] One aspect of the present invention relating to a thermal displacement correction method for an electric discharge machine is that an electric discharge is generated between the electrode (6) and the work piece (W) (D), and the work piece is generated by the discharge energy. In the thermal displacement correction method of the electric discharge machine (1) that processes (W), the first and second parts that cause changes in the relative positions of the electrode (6) and the workpiece (W) in a predetermined direction Among them, the relative position of the electrode (6) and workpiece (W) in the predetermined direction, which was experimentally obtained in advance, was determined in the first part where the thermal response speed in the predetermined direction with respect to the temperature change was slow It is characterized by blowing the outside air with the least air flow.

[0014] Here, for example, the electric discharge machine (1) includes a bed (2), a column (3) erected on the upper rear side of the bed (2), and a bed (2). And a table (4) on which the work piece (W) is placed and a head (5) held by the column (3) and having the electrode (6) mounted thereon, One part can be a bed (2) or a column (3).

[0015] Another aspect of the present invention relating to a thermal displacement correction method for an electric discharge machine is that an electric discharge is generated between the electrode (6) and the workpiece (W) (D), and the electric energy is covered by the discharge energy. In the thermal displacement correction method of the electric discharge machine (1) that processes the workpiece (W), the first and second that cause a change in the horizontal relative position of the electrode (6) and the workpiece (W). The first part with a slow thermal response speed in the horizontal direction to the temperature change, and the electrode (6) with the temperature change (6) It is characterized by blowing outside air with an air volume that minimizes the change in the relative position of the object (w) in the horizontal direction.

Here, for example, the electric discharge machine (1) includes a bed (2), a column body (7) and a column body (7) erected on the rear side of the upper surface of the bed (2). ), The column (3) is composed of the upper part of the column (8), and the table (4) is placed on the front side of the upper surface of the bed (2) on which the workpiece (W) is placed. And a head (5) that is held on the front surface of the column upper part (8) so that it is positioned above the table (4) and the electrode (6) is attached to the lower end of the table (4). The bed (2) can be the second part, the column top (8) and the head (5).

[0017] Still another aspect of the present invention relating to a thermal displacement correction method for an electric discharge machine is to generate an electric discharge between the electrode (6) and the work piece (W) (D), and the electric discharge energy In the thermal displacement correction method of the electric discharge machine (1) that processes the workpiece (W), the first and the second that cause a change in the relative position in the vertical direction between the electrode (6) and the workpiece (W). Of the second part, the first part, which has a slow thermal response speed in the vertical direction with respect to temperature change, is preliminarily experimentally determined between the electrode (6) and workpiece (W) that accompany temperature change. It is characterized by blowing outside air with an air volume that minimizes the change in the relative position in the vertical direction.

Here, for example, the electric discharge machine (1) includes a bed (2), a column body (7) and a column body (7) erected on the rear side of the upper surface of the bed (2). ), The column (3) is composed of the upper part of the column (8), and the table (4) is placed on the front side of the upper surface of the bed (2) on which the workpiece (W) is placed. And a head (5) that is held on the front surface of the column upper part (8) so that it is positioned above the table (4) and the electrode (6) is attached to the lower end of the table (4). Column (3) and the second part can be table (4), work piece (W), head (5), and electrode (6).

[0019] Further, in the case where the outside air is blown inside the first part, a cavity (21, 7 1) is formed inside, and an opening (23, 73) is formed in the first part, If the outside air is blown to (2 1, 7 1) and the blown outside air is discharged to the outside through the opening (2 3, 7 3), the flow of the blown outside air inside will be improved. It is more preferable because it approaches the outside temperature sooner.

[0020] Furthermore, if the air volume of the outside air to be blown is made constant, a complicated mechanism for controlling the air volume is not required, and thus the cost can be reduced.

In the present invention, the “relative position in the predetermined direction between the electrode and the workpiece” refers to an interval, that is, a distance in the predetermined direction between the electrode and the workpiece. “Change in relative position in a given direction” refers to the difference between the maximum and minimum intervals when the temperature is changed. “Slow thermal response speed” means that when the outside air temperature changes, it takes a long time for the entire temperature to reach the same temperature as the outside temperature after the change. Means that the time required is short.

[0022] In the present invention, the "first and second parts" have the same degree of linear thermal expansion in each of the parts in the predetermined direction (rate of change due to temperature change of the total length in the predetermined direction). More specifically, it is preferable that the respective linear thermal expansion coefficients are within a range of 70% to 1300% of the average value of the linear thermal expansion coefficients of the first and second portions. More preferably, it is in the range of 9 0 ⁰ / & to 110%, and more preferably in the range of 9 ⁵⁰ / & to 10 5%. The “part” may be composed of a plurality of constituent elements or may be composed of a single constituent element. Measure the total length in a given direction for each component before and after changing the temperature, especially when the `` part '' is composed of multiple components, especially when the components are spaced apart. Then, the linear thermal expansion coefficient in a predetermined direction is calculated from the values before and after the temperature change. In addition, when the “part” force is composed of a single constituent material such as a saddle made of a single material, the linear thermal expansion coefficient of the material may be used.

[0023] In the present invention, the "smallest air volume" is not limited to the actual minimum air volume, but also includes an air volume comparable to the air volume, for example, an air volume within a range of ± 10% of the air volume.

According to the applicant of the present application, even if the temperature change pattern is different, the relative position changes most. It has been confirmed by experiments that the same air volume decreases.

In the present invention, a predetermined amount of outside air may be blown not only to the first part but also to the second part. In this case, the air volume of the outside air blown to the first part is a relative position in the predetermined direction between the electrode and the workpiece due to a temperature change when the predetermined amount of outside air is blown to the second part. It is assumed that the air volume that minimizes the change in the air flow is experimentally determined in advance.

The invention's effect

[0025] According to the electric discharge machine and the thermal displacement correction method for an electric discharge machine of the present invention, one of the first and second parts that cause a change in the relative position of the electrode and the workpiece in a predetermined direction. Because the outside air with the air volume obtained experimentally in advance is blown to the first part where the thermal response speed in the specified direction with respect to the temperature change is slow, the thermal response speed of the first part where the thermal response speed is slow is increased. As a result, the first part and the second part can have substantially the same thermal response speed, and variations in the amount of thermal displacement with time due to temperature changes can be suppressed. The amount of air blown at this time is determined so that the change in the relative position in the predetermined direction between the electrode and the workpiece due to the temperature change is minimized, so the change in the relative position, that is, the relative displacement in the predetermined direction is effective. And the machining accuracy of the electrical discharge machine can be improved.

[0026] Further, since the air volume to be blown is a constant air volume obtained experimentally in advance, a complicated mechanism for controlling the air volume is not required, so that the cost can be reduced.

Brief Description of Drawings

FIG. 1 is a right side view of an electric discharge machine according to the present embodiment.

FIG. 2 is a graph showing the relationship between the passage of time when different air volumes are blown and the relative displacement in the Y-axis direction.

FIG. 3 is a graph showing the relationship between the passage of time and the amount of relative displacement in the Y-axis direction between an electric discharge machine with a fan attached and an electric discharge machine with no fan attached.

[Fig. 4] Time course when the outside air temperature is changed by 9 ° C, and the Y-axis and Z-axis directions It is a graph which shows the relationship with relative displacement amount.

Explanation of symbols

1 Electric discharge machine

2 Bed section

2 1 Cavity in bed

2 2 Bed side fan

2 3 Bed opening

3 Column section

4 Table section

5 Head section

6 electrodes

7 Column body

7 1 Column body cavity

7 2 Column side fan

7 3 Column side opening

8 Column top

8 1 Column upper cavity

9 Top

1 0 Shaft

D gap

W Workpiece

P Worker

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, an embodiment of an electric discharge machine according to the present invention will be described in detail with reference to the drawings. FIG. 1 is a schematic side view of an electric discharge machine 1 according to this embodiment. Note that, for the sake of convenience, the electric discharge machine 1 of the present embodiment is such that the side on which the electrode 6 is located is the upper side (upper side in FIG. 1), the side on which the bed portion 2 is located is the lower side (lower side in the drawing in FIG. The working side, that is, the opposite side through the column part 3 and the table part 4 is the front side (Fig. 1 In the horizontal direction, the front-rear direction (left-right direction in Fig. 1) is the Y-axis direction, and the up-down direction (up-down direction in Fig. 1) is the z-axis direction. In this specification, the amount of change in the total length of each part due to thermal expansion or contraction at each part is referred to as “thermal displacement”.

As shown in FIG. 1, the electric discharge machine 1 of the present embodiment includes a bed portion 2 installed on the floor surface, a column portion 3 erected on the rear side of the upper surface of the bed portion 2, The upper part of the bed part 2 is arranged in front of the column part 3 and placed on the front side of the column part 3 so as to be positioned above the table part 4 and the table part 4 on which the workpiece W is placed. The head part 5 is generally constituted by a held head part 5 and an electrode 6 attached to the lower end of the head part 5. The bed part 2, the column part 3, the table part 4 and the head part 5 are made of a material made of a material having the same linear thermal expansion coefficient.

[0031] The bed portion 2 is a rectangular parallelepiped having a flat upper surface, and has a bed portion internal cavity 21 therein. The column section 3 is erected on the upper surface of the bed section 2 substantially perpendicularly to the upper surface, and is a column main body 7 having a rectangular columnar shape and having a column body inner cavity 71 inside, and an upper end surface of the column body section 7. The upper and lower surfaces are substantially rectangular parallelepipeds arranged so that the upper and lower surfaces thereof are substantially perpendicular to the column main body 7, that is, parallel to the upper surface of the bed portion 2, and are composed of a column upper portion 8 having a column upper inner cavity 8 1 inside. Yes. At this time, the cavities 2 1, 7 1, 8 1 of the bed portion 2, the column main body portion 7, and the column upper portion 8 are separately formed.

[0032] The head unit 5 has a motor (not shown) installed therein, and an electrode 6 mounted on the lower end of the head unit 5 so as to be movable in the vertical direction. The table portion 4 has an upper surface and a lower surface formed in parallel with the upper surface of the bed portion 2, and the workpiece W is configured to be movable manually or automatically within the upper surface. The workpiece W is placed in a processing tank (not shown) in which a machining fluid is stored.

[0033] The electric discharge machine 1 configured as described above generates electric discharge by a power source (not shown) in the gap D between the electrode 6 and the workpiece W in the machining liquid stored in the machining tank. The workpiece W is EDMed by the discharge energy.

[0034] A characteristic of the present invention is that the relative position between the electrode 6 and the workpiece W in a predetermined direction. Among the first and second parts that cause a change in temperature, the first part with a slow thermal response speed in a given direction with respect to the temperature change has a temperature change that has been experimentally determined in advance. It is to blow the outside air with the air volume that minimizes the change in the relative position of the electrode and the workpiece in the predetermined direction.

[0035] Since the first and second portions in the electric discharge machine 1 of the present embodiment cause a change in the relative position between the electrode and the workpiece by causing thermal displacement, the Y-axis direction is The first part is the bed part 2, the second part is the upper part 9 formed by combining the column upper part 8 and the head part 5, and the first part is the column part 3 and the second part is the table part 4 in the Z-axis direction. The shaft part 10 is a combination of the workpiece W, the head part 5 and the electrode 6. The X-axis direction, which is the left-right direction when viewed from the front side, that is, the depth direction of the paper, is that the electrical discharge machine 1 is configured substantially symmetrically when viewed from the front side. Therefore, in this embodiment, it is not considered.

First, a method for correcting thermal displacement in the Y-axis direction will be described. Normally, the bed part 2 of the electrical discharge machine 1 has the column part 3 etc. on the upper surface, so the outer shape such as thickness is designed larger than the upper part 9 in consideration of strength and stability. ing. For this reason, the heat capacity of the bed part 2 is larger than the heat capacity of the upper part 9, and if there is a temperature change around the EDM 1, the bed part 2 and the upper part 9 will There is a difference in change. If there is a difference in temperature change, the amount of thermal displacement of the bed part 2 in the total Y-axis direction (Y1 in Fig. 1) and the total length of the upper 9 in the Y-axis direction (Y2 in Fig. 1) The amount of thermal displacement is different, and this causes a change in the relative position of the electrode 6 and the workpiece W in the Y-axis direction. Further, as described above, the heat capacity of the bed part 2 is larger than that of the upper part 9, so that the time required for the bed part 2 and the upper part 9 to reach a uniform temperature is higher than that of the upper part 9. A lot is needed. That is, bed 2 has a slower thermal response than upper 9.

Therefore, the thermal displacement correction method of the electric discharge machine 1 according to the present embodiment, as shown in FIG. 1, is applied to the front wall of the bed portion 2 on the front wall of the bed portion 2, which has been experimentally determined in advance, Subject The bed side fan 2 2 set to blow the outside air with the air volume that minimizes the change in the relative position in the Y-axis direction with the object W is installed, and the bed internal cavity 2 1 is forced. To blow outside air. At this time, a bed side opening 23 that discharges the outside air blown to the rear wall of the bed portion 2 to the outside is formed, and the air flow in the cavity 21 is improved, so that the bed portion 2 is removed earlier. Increase the thermal response speed closer to the air temperature.

[0038] Hereinafter, an experiment for determining the air volume will be described. Fig. 2 shows a graph showing the relationship between the passage of time and the relative displacement in the axial direction when outside air with different air volumes is blown into the cavity 21 by controlling the rotational speed of the fan 22. The number of the curve in FIG. 2 is a curve with a small air volume with a small number, and shows a curve with a large air volume as the number increases. Here, Ν ο 1 shows the curve when the air volume is 0. The amount of change in the outside air temperature was 9 ° C, and the same change as the outside air temperature curve in Fig. 3 described later was made.

As shown in FIG. 2, when the outside air is blown into the cavity 21, the relative displacement amount in the Y-axis direction changes in conjunction with a change in the outside air temperature (not shown). When the air flow is small (No 1-3), there is a difference in the thermal response speed between the bed 2 and the upper part 9, so the total length of the bed 2 in the Y-axis direction for each hour (Y1 in Fig. 1) ) And the total length of the upper Y-axis direction (Y2 in Fig. 1), the relative displacement in the Y-axis direction when the outside air temperature is changed by 9 ° C. When the amount is large, it is about 14 m, and the relative displacement in the Y-axis direction cannot be sufficiently suppressed.

[0040] When the air volume is large (No 4-7), a large amount of outside air is blown into the cavity 21, so that the bed 2 approaches the outside temperature faster and the thermal response speed of the bed 2 becomes faster. As a result, the difference in thermal response speed between the bed part 2 and the upper part 9 is reduced, so that the amount of thermal displacement of the bed part 2 in the entire length in the Y-axis direction (Y1 in Fig. 1) and the upper 9 The difference in thermal displacement in the overall length in the Y-axis direction (Y2 in Fig. 1) can be reduced, and the relative displacement in the Y-axis direction when the outside air temperature is changed by 9 ° C is within 5 m. Can be suppressed.

[0041] Here, when the air volume is No 6 or 7 among the above large air volumes, the outside air is in the cavity 21. Therefore, the bed part 2 quickly approaches the outside air temperature, and the thermal response speed of the bed part 2 becomes faster than that of the upper part 9, so that the phase in the time period of the curve is as shown in FIG. Reverse. In this experiment, when the air volume is N o 5 or N o 6, the relative displacement amount in the Y-axis direction is the most suppressed, but when the EDM 1 is required to have higher machining accuracy, By finely setting the air volume between the air volume N o 5 and the air volume N o 6, a value that can further suppress the relative displacement in the Y-axis direction can be obtained.

[0042] Here, FIG. 3 is a graph showing the relationship between the passage of time and the relative displacement in the Y-axis direction when the outside air having the air volume determined as described above is blown into the cavity 21 by the fan 22. Indicates. At this time, the change in the temperature of the outside air was 9 ° C. Specifically, the temperature was increased by 9 ° C at 2 ° C / hour, and after 2 hours, it was decreased by 9 ° C at 2 ° C / hour. After 2 hours, the temperature was increased by 9 ° C at 2 ° C / hour, and after 8 hours, the temperature was decreased by 9 ° C at 2 ° C / hour. After 2 hours, the temperature was further increased by 9 ° C at 2 ° C / hour, and after 2 hours, the temperature was decreased by 9 ° C at 2 ° C / hour. Note that the curve without fan in FIG. 3 is the same data as the curve of No 1 in FIG. 2 described above.

[0043] As shown in FIG. 3, in the electric discharge machine 1 in which the fan 2 2 is not attached to the bed part 2, the relative displacement in the Y-axis direction increased to about 1 in conjunction with the change in the outside air temperature. In EDM 1 with fan 2 2 attached to bed part 2, the phase in the time period was reversed from the change in outside air temperature, and the relative displacement in the Y-axis direction changed within 4 m.

[0044] As described above, since the outside air having the air volume determined as described above is blown into the cavity 21 by the fan 22, the thermal response speed of the bed portion 2 can be increased. The difference in thermal response speed between the head 2 and the upper part 9 can be reduced, and the difference in the amount of thermal displacement between the bed 2 and the upper part 9 in the Y-axis direction for each time can be reduced. As a result, the amount of relative displacement in the Y-axis direction is suppressed, so that the machining accuracy of the electric discharge machine 1 can be improved. In addition, since the air volume is constant, the cost can be reduced by not requiring a complicated mechanism for controlling the air volume. Furthermore, the air flow is the relative position of the electrode 6 and workpiece W in the Y-axis direction as the temperature changes. Therefore, the relative position can be effectively reduced, that is, the relative displacement in the Y-axis direction can be effectively suppressed, and the machining accuracy of the electric discharge machine 1 can be improved.

Next, a method for correcting thermal displacement in the Z-axis direction will be described. In general, the column part 3 of the electric discharge machine 1 holds the electrode 6 in a predetermined position via the head part 5, so that the outer shape is larger than that of the shaft part 10 described above in consideration of strength and stability. Largely designed. For this reason, the heat capacity of the column part 3 is larger than the heat capacity of the shaft part 10, and when a temperature change occurs around the electric discharge machine 1, the column part 3 and the shaft part 10 are affected by the difference in heat capacity. Is different from the temperature change. If there is a difference in temperature change, the amount of thermal displacement in the Z-axis direction of the column 3 (Z 1 in Fig. 1) and the size of the shaft 10 in the Z-axis direction (in Fig. 1, The amount of thermal displacement in Z 2) becomes a different value, which changes the relative position of the electrode 6 and the workpiece W in the Z-axis direction. Also, as described above, the heat capacity of the column part 3 is larger than the heat capacity of the shaft part 10, so the time required to bring the column part 3 and the shaft part 10 to a uniform temperature is equal to the column part 3. Is required more than the shaft portion 10. That is, the column part 3 has a slower thermal response speed than the shaft part 10.

Therefore, the thermal displacement correction method for the electric discharge machine 1 according to the present embodiment is, as shown in FIG. A column-side fan 72 that is set so as to blow the outside air with an air volume that minimizes the change in the relative position in the Z-axis direction of the space D is attached, and the outside air is forcibly blown into the column body internal cavity 71. At this time, a column side opening 73 is formed at the upper end of the rear wall of the column main body 7 to activate the ventilation of the cavity 71 more. In the electric discharge machine 1 of the present embodiment, ventilation by the fan 72 is performed only in the cavity 71 in order to reduce the influence on the Y-axis direction thermal displacement correction described above. The air volume is determined by the same experimental method as in the Y-axis direction described above, and the description of the experimental method in the Z-axis direction is omitted. The experiment in the Z-axis direction was performed with the workpiece W immersed in the machining fluid, and the machining fluid temperature was controlled to the same temperature as the column 7 temperature. Assumed to be performed. [0047] In the electric discharge machine 1 of the present embodiment configured as described above with reference to FIG. 4, the passage of time and the relative displacement in the Y-axis direction and the Z-axis direction when the outside air temperature is changed by 9 ° C. The graph which shows the relationship with is shown. As shown in FIG. 4, the amount of relative displacement in the Y-axis direction could be suppressed within about 4.5 Om, and the amount of relative displacement in the Z-axis direction could be suppressed within about 2.5 m.

[0048] As described above, according to the electric discharge machine 1 and the thermal displacement correction method of the electric discharge machine 1 according to the present embodiment, a change is caused in the relative position of the electrode 6 and the workpiece W in a predetermined direction. Among the second parts, the outside air is blown into the first part where the thermal response speed in the predetermined direction with respect to the temperature change is slow, so the thermal response speed of the first part with a slow thermal response speed is increased. By doing so, the first part and the second part can have substantially the same thermal response speed, and variations in the amount of thermal displacement with time due to temperature changes can be suppressed. The amount of air blown at this time is determined so that the change in the relative position in the predetermined direction between the electrode and the workpiece due to the temperature change is minimized, so that the relative position change, that is, the relative displacement in the predetermined direction is effectively determined. It can be suppressed and the machining accuracy of the electric discharge machine can be improved.

[0049] In addition, since the air volume to be blown is a constant air volume obtained experimentally in advance, a complicated mechanism for controlling the air volume is not required, so that the cost can be reduced. Therefore, the electric discharge machine can process the workpiece with high accuracy.

[0050] The above-mentioned measurement of the relative displacement in the Y-axis direction and the Z-axis direction is obtained by a commonly used measurement method. For example, a reference sphere is installed at the position of the electrode 6 and the workpiece W. The method of measuring is used.

[0051] Further, as described above, the electric discharge machine 1 of the present embodiment has the fan attached to the bed part 2 and the column main body part 7, but the electric discharge machine of the present invention is not limited to this. For example, you may attach a fan only to a bed part.

Further, as described above, the electric discharge machine 1 of the present embodiment has the fan 22 attached to the front surface of the bed part 2, but the electric discharge machine of the present invention is not limited to this, for example, Even if the bed side fan is installed on the right side, the bed on the left side A side fan may be attached, and the design can be changed as appropriate.

[0053] Further, as described above, the electric discharge machine 1 of the present embodiment is such that the fan 72 is attached to the lower end of the rear surface of the column main body 7. However, the electric discharge machine of the present invention is limited to this. For example, it may be attached to the upper end or the front, and the design can be changed as appropriate.

Further, as described above, the electric discharge machine 1 of the present embodiment blows outside air into the column main body and the bed part, but the electric discharge machine of the present invention is not limited to this. For example, outside air may be blown to the outer surface.

[0055] Although the electric discharge machine 1 of the present embodiment has a shape collectively referred to as a C-shaped frame as described above, the electric discharge machine of the present invention and the thermal displacement correction method in the electric discharge machine are not limited thereto. For example, it may be a shape generally referred to as a portal frame having column main body portions on both the left and right sides, and the design can be changed as appropriate. In the case of an EDM machine with a portal frame, to correct the thermal displacement in the Z-axis direction, attach the column-side fans to the left and right columns.

Claims

The scope of the claims

[1] In an electric discharge machine that generates an electric discharge between an electrode and a workpiece, and processes the workpiece by electric discharge energy.

Of the first and second parts that cause a change in the relative position of the electrode and the workpiece in a predetermined direction, the first part having a slow thermal response speed in the predetermined direction with respect to a temperature change is tested in advance. Discharge characterized by comprising a blowing means for blowing outside air having an air volume that minimizes a change in the relative position in the predetermined direction between the electrode and the workpiece in accordance with a temperature change. Processing machine.

[2] The electric discharge machine includes a bed, a column erected on the rear side of the upper surface of the bed, and a table placed on the front side of the upper surface of the bed and on which the workpiece is placed. The electric discharge machine according to claim 1, wherein the first part is the bed or the column.

[3] In an electric discharge machine that generates an electric discharge between an electrode and a workpiece, and processes the workpiece by electric discharge energy.

Of the first and second parts that cause a change in the relative position in the horizontal direction between the electrode and the workpiece, the first part that has a slow thermal response speed in the horizontal direction with respect to a temperature change It is characterized by comprising a blowing means that blows outside air having an air volume that minimizes a change in the relative position in the horizontal direction between the electrode and the work piece, which is experimentally determined, according to a temperature change. Electric discharge machine.

[4] The electric discharge machine comprises a bed, a column body erected on the rear side of the upper surface of the bed, and a column upper part disposed on an upper end surface of the column body. A table placed on the front side of the upper surface of the bed and on which the workpiece is placed, and held on the front surface of the upper part of the column so as to be positioned above the table, the electrode is mounted on the lower end. The electric discharge machine according to claim 3, further comprising: a head, wherein the first portion is the bed, and the second portion is the column upper portion and the head. .

[5] A discharge is generated between the electrode and the workpiece, and the workpiece is processed by discharge energy. In an electric discharge machine that processes objects,

Of the first and second parts that cause a change in the relative position in the vertical direction between the electrode and the workpiece, the first part having a slow thermal response speed in the vertical direction with respect to a temperature change is It is characterized by comprising a blowing means for blowing outside air having an air volume that minimizes a change in the relative position in the vertical direction between the electrode and the work piece, which is experimentally determined, according to a temperature change. Electric discharge machine.

[6] The electric discharge machine comprises a bed, a column main body erected on the rear side of the upper surface of the bed, and a column upper portion disposed on an upper end surface of the column main body. A table placed on the front side of the upper surface of the bed and on which the workpiece is placed, and held on the front surface of the upper part of the column so as to be positioned above the table, the electrode is mounted on the lower end. 6. The head according to claim 5, wherein the first part is the column, and the second part is the table, the workpiece, the head, and the electrode. The electric discharge machine described in 1.

[7] When the outside air is blown into the first portion, a cavity for blowing the outside air is formed in the inside, and the blown outside air is discharged to the first portion to the outside. The electric discharge machine according to claim 1, wherein an opening is formed.

[8] In a thermal displacement correction method for an electric discharge machine, in which an electric discharge is generated between an electrode and a workpiece, and the workpiece is machined by discharge energy.

Of the first and second parts that cause a change in the relative position of the electrode and the workpiece in a predetermined direction, the first part having a low thermal response speed in the predetermined direction with respect to a temperature change Experimentally determined thermal displacement of an electric discharge machine characterized by blowing air with an air volume that minimizes the change in relative position in the predetermined direction between the electrode and the workpiece with temperature change. Correction method.

[9] The electric discharge machine includes: a bed; a column erected on the rear side of the upper surface of the bed; and a table on which the workpiece is placed and disposed on the front side of the upper surface of the bed. The head that is held by the column and to which the electrode is attached, and wherein the first portion is the bed or the column. Method for correcting thermal displacement of electrical discharge machine.

[10] In a thermal displacement correction method for an electric discharge machine that generates an electric discharge between an electrode and a workpiece, and processes the workpiece by electric discharge energy.

Of the first and second parts that cause a change in the relative position in the horizontal direction between the electrode and the workpiece, the first part that has a slow thermal response speed in the horizontal direction with respect to a temperature change Experimentally obtained thermal displacement of an electric discharge machine that blows outside air with an air volume that minimizes a change in the relative position in the horizontal direction between the electrode and the workpiece due to a temperature change. Correction method.

[1 1] The electric discharge machine includes a bed, a column main body erected on the rear side of the upper surface of the bed, and a column upper portion disposed on an upper end surface of the column main body. A column, a table arranged on the front side of the upper surface of the bed and on which the workpiece is placed, and held on the front surface of the column upper portion so as to be positioned above the table, and the electrode is mounted on the lower end. The discharge according to claim 10, characterized in that: the first portion is the bed, and the second portion is the column upper portion and the head. Method for correcting thermal displacement of processing machines.

[12] In a method for correcting a thermal displacement of an electric discharge machine, wherein an electric discharge is generated between an electrode and a workpiece, and the workpiece is machined by discharge energy.

Of the first and second parts that cause a change in the relative position in the vertical direction between the electrode and the workpiece, the first part having a slow thermal response speed in the vertical direction with respect to a temperature change is Experimentally obtained thermal displacement of an electric discharge machine that blows outside air with an air volume that minimizes a change in the relative position in the vertical direction between the electrode and the workpiece with temperature change. Correction method.

[13] The electric discharge machine comprises a bed, a column main body erected on the rear side of the upper surface of the bed, and a column upper portion disposed on the upper end surface of the column main body. A table placed on the front side of the upper surface of the bed and on which the workpiece is placed, and held on the front surface of the upper part of the column so as to be positioned above the table, the electrode is mounted on the lower end. And the first part is the column, and the second part is the table, the workpiece, the head, and The method of correcting a thermal displacement of an electric discharge machine according to claim 12, wherein the electrode is the electrode.

[14] In the case where the outside air is blown into the first portion, a cavity is formed in the inside, an opening is formed in the first portion, and the outside air is blown into the cavity. The method of correcting a thermal displacement of an electric discharge machine according to any one of claims 8 to 13, wherein the blown outside air is discharged to the outside through the opening.

15. The method for correcting a thermal displacement of an electric discharge machine according to claim 8, wherein the air volume of the blown outside air is made constant.