Wire Electric Discharge Machine

Abstract

The wire electric discharge machine (100) includes a machining tank (6), a wire electrode (7), a lower arm (8), a lower wire guide (10), and a bellows member (11). The machining tank (6) has an opening (60) through which the lower arm (8) passes. The bellows member (11) is arranged so that an opening at one end of the cylindrical shape is closed and the other end surrounds the periphery of the opening (60) of the machining tank (6), and closes the gap between the cylindrical interior of the bellows member (11) and the interior of the machining tank (6) in which the machining fluid is stored, so that machining fluid will not leak from inside the machining tank (6) even if the relative position between the lower wire guide (10) and the machining tank (6) changes.

Description

[Technical field]

[0001] The present disclosure relates to a wire electric discharge machine. [Background technology]

[0002] Conventionally, a wire electric discharge machine is known that processes a workpiece by generating a voltage between the workpiece and a wire electrode to cause an electric discharge. For example, Patent Document 1 discloses an electric discharge machining device including a machining tank in which machining fluid is stored, a lower guide arm extending from the inside to the outside of the machining tank, and a cylindrical bellows-shaped seal member surrounding the periphery of the lower guide arm outside the machining tank. The machining tank is formed with a long hole opening through which the lower guide arm passes. Flanges are provided on both ends of the bellows-shaped seal member along the opening edges of the both ends. The flanges provided on one end of the bellows-shaped seal member are attached from the outside of the machining tank along the opening edges of the long hole opening to close the long hole opening and seal between the bellows-shaped seal member and the long hole opening. The flanges provided on the other end of the bellows-shaped seal member are attached to a column provided on the upper surface of a base to seal between the bellows-shaped seal member and the column. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 7-1241 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the technology described in Patent Document 1, since the inside of the machining tank and the inside of the bellows-shaped seal member are connected, the inside of the bellows-shaped seal member is filled with machining fluid. That is, the lower guide arm arranged inside the bellows-shaped seal member is immersed in the machining fluid. Therefore, when the temperature of the machining fluid rises due to machining of the workpiece, the lower guide arm holding the wire electrode thermally expands, and the wire electrode may shift from the target position, deteriorating the machining accuracy of the workpiece. In addition, machining chips from the workpiece that have entered the inside of the bellows-shaped seal member together with the machining fluid accumulate in the grooves on the inner surface of the bellows over time, and the machining chips become a load on the expansion and contraction of the bellows-shaped seal member, which may degrade the machining accuracy of the workpiece.

[0005] The present disclosure has been made in consideration of the above, and has an object to provide a wire electric discharge machine that can suppress deterioration in machining accuracy of a workpiece. [Means for solving the problem]

[0006] In order to solve the above-mentioned problems and achieve the object, the wire electric discharge machine according to the present disclosure comprises a machining tank in which machining fluid is stored, a wire electrode which generates an electric discharge between the workpiece immersed in the machining fluid in the machining tank and performs electric discharge machining on the workpiece, a lower arm extending from the inside to the outside of the machining tank, a lower wire guide attached to the lower arm and placed inside the machining tank to hold the wire electrode, and a cylindrical bellows member placed inside the machining tank and surrounding the lower arm located inside the machining tank. The machining tank has an opening through which the lower arm passes. The bellows member has an opening at one of its cylindrical ends which is closed, and the other end which is placed so as to surround the opening of the machining tank. Connected to the inner surface of the processing tank The bellows member closes the gap between the cylindrical interior of the machining tank and the interior of the machining tank in which the machining fluid is stored so that machining fluid will not leak from inside the machining tank even if the relative position of the lower wire guide and the machining tank changes. Effect of the Invention

[0007] The wire electric discharge machine according to the present disclosure has the advantage of being able to suppress deterioration in the machining accuracy of the workpiece. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a perspective view showing a wire electric discharge machine according to an embodiment; [Diagram 2] FIG. 1 is a front view showing a wire electric discharge machine according to an embodiment of the present invention; [Diagram 3] FIG. 1 is a side view showing a wire electric discharge machine according to an embodiment of the present invention; [Figure 4] FIG. 1 is an enlarged view of a main part of a wire electric discharge machine according to an embodiment of the present invention; [Diagram 5] Cross-sectional view taken along line VV in Figure 2 [Figure 6] FIG. 6 is a cross-sectional view showing a schematic view of a main part taken along line VI-VI in FIG. 5. [Figure 7] FIG. 7 is a cross-sectional view showing a schematic view of the VII-VII arrows shown in FIG. [Figure 8] FIG. 8 is a cross-sectional view showing a main part taken along line VIII-VIII in FIG. 5 . [Figure 9] FIG. 9 is a perspective view of the main part shown in FIG. [Figure 10] FIG. 1 is an explanatory diagram showing a state in which the machining tank is moved in the X-axis direction in the wire electric discharge machine according to the embodiment; [Figure 11] FIG. 1 is an explanatory diagram showing a state in which the machining tank is moved in the Y-axis direction in the wire electric discharge machine according to the embodiment; [Figure 12] FIG. 13 is a perspective view showing a modified example of the wire electric discharge machine according to the embodiment. [Figure 13] FIG. 1 is an explanatory diagram illustrating a schematic example of a wire electric discharge machine according to a comparative example; [Figure 14] FIG. 10 is an explanatory diagram showing an example of a lower arm and a bellows member of a wire electric discharge machine according to a comparative example; [Figure 15] FIG. 15 is an explanatory diagram showing a wire electric discharge machine of a comparative example, in which the bellows member is expanded or contracted along the X-axis direction from the state shown in FIG. 14 . [Figure 16]FIG. 8 is an explanatory diagram showing a wire electric discharge machine according to an embodiment, in which the bellows member is expanded or contracted along the X-axis direction from the state shown in FIG. 7; DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A wire electric discharge machine according to an embodiment of the present disclosure will be described below in detail with reference to the drawings.

[0010] Embodiment FIG. 1 is a perspective view of a wire electric discharge machine according to an embodiment. FIG. 2 is a front view of the wire electric discharge machine according to an embodiment. FIG. 3 is a side view of the wire electric discharge machine according to an embodiment. FIG. 4 is an enlarged view of a main part of the wire electric discharge machine according to an embodiment. FIG. 5 is a cross-sectional view taken along the line VV in FIG. 2. FIG. 6 is a cross-sectional view taken along the line VI-VI in FIG. 5, showing a schematic cross-sectional view of a main part. FIG. 7 is a cross-sectional view taken along the line VII-VII in FIG. 6. In FIGS. 1 to 5, a machining tank 6 is shown by a dashed line in order to clearly show other components.

[0011] 1, a wire electric discharge machine 100 according to this embodiment machines a workpiece W by immersing the workpiece W inside a machining tank 6 in which machining fluid is stored and generating a voltage between the workpiece W and a wire electrode 7 to cause discharge. The wire electric discharge machine 100 according to this embodiment includes a bed 1, a column 2, a Y-axis table 3, an X-axis table 4, a Z-axis base 5, the machining tank 6, the wire electrode 7, a lower arm 8, an upper wire guide 9, a lower wire guide 10, and a bellows member 11.

[0012] As shown in Figs. 1 to 3, bed 1 is the base of wire electric discharge machine 100. A column 2 is installed on the rear side of the upper surface of bed 1, and a Y-axis table 3 is installed on the front side. The column 2 has a lower end fixed to bed 1 and is installed so as to extend upward from the upper surface of bed 1. A Z-axis base 5 is provided on the upper part of column 2, extending horizontally from column 2 toward the front. A lower arm 8 is provided on the lower part of column 2, extending horizontally from column 2 toward the front.

[0013] As shown in FIG. 1 to FIG. 3, the Y-axis table 3 moves in the Y-axis direction along the direction from the back surface of the bed 1 to the front surface. The Y-axis table 3 moves the X-axis table 4 and the machining tank 6 in the Y-axis direction by itself moving. The X-axis table 4 is installed on the upper surface of the Y-axis table 3. The X-axis table 4 moves in the X-axis direction perpendicular to the Y-axis direction in the horizontal direction. The X-axis table 4 moves the machining tank 6 in the X-axis direction by itself moving. The Y-axis table 3 and the X-axis table 4 may be arranged in reverse. That is, the X-axis table 4 may be arranged on the upper surface of the bed 1, and the Y-axis table 3 may be arranged on the upper surface of the X-axis table 4. The Z-axis base 5 is installed on the upper part of the column 2 so as to protrude from the column 2 toward the front surface. The machining tank 6 is arranged below the Z-axis base 5. The Z-axis base 5 is configured to be movable in the Z-axis direction (up and down direction) along the column 2 by a moving mechanism not shown. An upper wire guide 9 is attached to the tip of the Z-axis base 5. The driving of the Y-axis table 3, the X-axis table 4 and the Z-axis base 5 is controlled simultaneously or separately by a controller (not shown). Note that the horizontal direction mentioned above does not have to be strictly horizontal, but may be approximately horizontal.

[0014] As shown in Figs. 1 to 3, the machining tank 6 is installed on the upper surface of the X-axis table 4. The machining tank 6 can be moved in the Y-axis direction and the X-axis direction by the Y-axis table 3 and the X-axis table 4. Machining fluid is stored inside the machining tank 6. The workpiece W is fixed inside the machining tank 6 and immersed in the machining fluid. By immersing the workpiece W in the machining fluid, deterioration of machining accuracy due to thermal expansion and thermal contraction of the workpiece W can be suppressed. As shown in Fig. 6, an opening 60 through which the lower arm 8 passes is formed on the back surface of the machining tank 6 facing the column 2.

[0015] As shown in Fig. 4, the wire electrode 7 generates an electric discharge between the wire electrode 7 and the workpiece W immersed in the machining fluid in the machining tank 6, thereby machining the workpiece W. The upper end of the wire electrode 7 is held by an upper wire guide 9. The lower end of the wire electrode 7 is held by a lower wire guide 10. The wire electrode 7 is fed by a wire feeding mechanism (not shown) and taken up by a wire take-up mechanism (not shown).

[0016] As shown in Figs. 3 to 5, the lower arm 8 is provided at the lower part of the column 2 so as to protrude from the column 2 toward the front. The lower arm 8 extends from the inside to the outside of the machining tank 6 through an opening 60. As shown in Fig. 7, the lower arm 8 has a rectangular cross section and a flat upper surface. A lower wire guide 10 is attached to the tip of the lower arm 8. The rear end of the lower arm 8 is fixed to the column 2 by a fixing member such as a bolt.

[0017] 1 to 3, the upper wire guide 9 is attached to the tip of the Z-axis base 5 and holds the upper end of the wire electrode 7 above the workpiece W. The upper wire guide 9 moves in the Z-axis direction together with the Z-axis base 5 as the Z-axis base 5 moves.

[0018] 3 and 4, the lower wire guide 10 is attached to the tip of the lower arm 8 and disposed inside the machining tank 6. The lower wire guide 10 holds the lower end of the wire electrode 7 below the workpiece W. The wire electric discharge machine 100 uses the wire electrode 7 positioned by the upper wire guide 9 and the lower wire guide 10 to machine the workpiece W into a desired shape.

[0019] FIG. 8 is a cross-sectional view showing the main part of the wire guide 10 taken along the line VIII-VIII in FIG. 5. FIG. 9 is a perspective view of the main part of the wire guide 10 shown in FIG. 8. As shown in FIG. 8 and FIG. 9, the lower wire guide 10 has a holding part 10a, an insulating member 10b, and an intermediate member 10c. The holding part 10a holds the lower end of the wire electrode 7. The insulating member 10b is a flat plate-shaped member. The insulating member 10b is made of, for example, a ceramic material such as alumina or glass-reinforced epoxy resin. The insulating member 10b has one side attached to the holding part 10a and the other side opposite to the one side attached to the tip surface of the lower arm 8, thereby insulating the holding part 10a from the lower arm 8. The intermediate member 10c is, for example, a square steel pipe. The intermediate member 10c is attached to the insulating member 10b, and the lower arm 8 passes through the inside of the intermediate member 10c. At both ends of the intermediate member 10c, flange parts 10d and 10e are formed along the opening edge. One flange portion 10d of the intermediate member 10c is fixed to the insulating member 10b with a fixing member 13 such as a screw. A seal member 17 such as a packing is provided between the flange portion 10d and the insulating member 10b. An opening of one end of the intermediate member 10c fixed to the insulating member 10b is blocked by the insulating member 10b. The lower wire guide 10 is attached to the tip of the lower arm 8 by fixing the insulating member 10b to the tip surface of the lower arm 8, which is inserted into the cylinder of the intermediate member 10c, with a fixing member 14 such as a screw.

[0020] As shown in Fig. 7, bellows member 11 has a rectangular cylindrical shape. As shown in Figs. 6 to 9, bellows member 11 is disposed inside machining tank 6 and surrounds the periphery of lower arm 8 located inside machining tank 6. Bellows member 11 is disposed so that an opening at one of both ends of the cylinder is closed and the other end surrounds the periphery of opening 60 of machining tank 6, thereby closing the space between the cylindrical interior of bellows member 11 and the interior of machining tank 6 in which machining fluid is stored.

[0021] 8 and 9, the bellows member 11 has a cylindrical main body 11a having a bellows structure, a first connection portion 11b provided at one end of the main body 11a, and a second connection portion 11c provided at the other end of the main body 11a. The main body 11a is made of, for example, synthetic rubber or synthetic resin. The main body 11a has a rectangular cylindrical shape and has a flat surface facing the flat upper surface of the lower arm 8. The main body 11a surrounds the lower arm 8 located inside the processing tank 6.

[0022] The first connecting portion 11b is, for example, a flange provided along the opening edge of the main body portion 11a. The first connecting portion 11b is, for example, a metal fitting. The first connecting portion 11b is connected to the other flange portion 10e of the intermediate member 10c by a fixing member 15 such as a screw. A seal member 18 such as a packing is provided between the first connecting portion 11b and the flange portion 10e of the intermediate member 10c. In addition, the second connecting portion 11c is, for example, a flange provided along the opening edge of the main body portion 11a. The second connecting portion 11c is, for example, a metal fitting. The second connecting portion 11c abuts along the periphery of the opening 60 from the inside of the processing tank 6 and is connected to the inner surface of the processing tank 6 by a fixing member 16 such as a screw. A seal member 19 such as a packing is provided between the second connecting portion 11c and the inner surface of the processing tank 6. That is, the bellows member 11 is attached to the machining tank 6 with the first connection portion 11b attached to the lower wire guide 10, an opening provided at one end blocked by the insulating member 10b, and the second connection portion 11c disposed so as to surround the periphery of the opening 60 of the machining tank 6. In this way, even if the relative position between the lower wire guide 10 and the machining tank 6 changes on a plane in which the machining tank 6 can move, the bellows member 11 blocks the gap between the inside of the cylinder of the bellows member 11 and the interior of the machining tank 6 in which the machining fluid is stored, so that the machining fluid in the machining tank 6 does not leak into the cylinder of the bellows member 11 over the entire range of the change.

[0023] The first connecting portion 11b and the second connecting portion 11c are not limited to the flanges shown in the drawings, and may have other shapes. The first connecting portion 11b is not limited to a configuration in which it is attached to the insulating member 10b of the lower wire guide 10 via the intermediate member 10c, and may be attached directly to the insulating member 10b of the lower wire guide 10, for example. In short, the first connecting portion 11b and the second connecting portion 11c may have any configuration as long as they can seal the space between the cylindrical interior of the bellows member 11 and the inside of the processing tank 6.

[0024] FIG. 10 is an explanatory diagram showing a state in which the machining tank is moved in the X-axis direction in the wire electric discharge machine according to the embodiment. FIG. 11 is an explanatory diagram showing a state in which the machining tank is moved in the Y-axis direction in the wire electric discharge machine according to the embodiment. Note that the outline arrows shown in FIG. 10 and FIG. 11 indicate the movement direction of the machining tank 6. In addition, in FIG. 10 and FIG. 11, the machining tank 6 is shown by a dashed line in order to clearly show other components. As shown in FIG. 10, the bellows member 11 expands and contracts in the X-axis direction by the movement of the X-axis table 4. Also, as shown in FIG. 11, the bellows member 11 expands and contracts in the Y-axis direction by the movement of the Y-axis table 3. That is, the bellows member 11 expands and contracts in two axial directions, the X-axis direction and the Y-axis direction.

[0025] Fig. 12 is a perspective view showing a modified example of the wire electric discharge machine according to the embodiment. As shown in Fig. 12, the bellows member 11 may be trapezoidal in plan view so that the internal space expands from one end attached to the lower wire guide 10 toward the other end attached to the inner surface of the machining tank 6. The bellows member 11 is not limited to the rectangular shape in plan view shown in Fig. 5 or the trapezoid shape shown in Fig. 12, and may be of any other shape, such as an oval shape in vertical cross section, as long as it is expandable in two axial directions, that is, the X-axis direction and the Y-axis direction.

[0026] Fig. 13 is an explanatory diagram that shows a schematic diagram of an example of a wire electric discharge machine of a comparative example. As shown in Fig. 13, in the wire electric discharge machine 100A of the comparative example, a cylindrical bellows member 12 is arranged outside the machining tank 6. The machining tank 6 is formed with an opening 60 through which the lower arm 8 passes. One end of the bellows member 12 is arranged along the edge of the opening 60 and is attached to the outer surface of the machining tank 6 with a fixing member such as a screw to close the gap with the opening 60. The other end of the bellows member 12 is attached to the side surface of the column 2 with a fixing member such as a screw.

[0027] In the comparative wire electric discharge machine 100A shown in FIG. 13, the inside of the machining tank 6 and the inside of the bellows member 12 are connected, so that the inside of the bellows member 12 is filled with machining fluid. That is, the lower arm 8 arranged inside the bellows member 12 is immersed in the machining fluid. For this reason, when the temperature of the machining fluid rises due to machining of the workpiece W, the lower arm 8 thermally expands, and the wire electrode may shift from the target position, deteriorating the machining accuracy of the workpiece W. In addition, machining chips that have entered the inside of the bellows member 12 together with the machining fluid may accumulate in the grooves on the inner surface of the bellows member 12 over time, and the machining chips may become a load for the expansion and contraction of the bellows member 12, deteriorating the machining accuracy of the workpiece W.

[0028] On the other hand, the wire electric discharge machine 100 according to the present embodiment includes a machining tank 6 in which machining fluid is stored, a wire electrode 7 which generates an electric discharge between the machining tank 6 and a workpiece W immersed in the machining fluid to machine the workpiece W, a lower arm 8 which extends from the inside to the outside of the machining tank 6, a lower wire guide 10 which is attached to the lower arm 8 and disposed inside the machining tank 6 to hold the wire electrode 7, and a cylindrical bellows member 11 which is disposed inside the machining tank 6 and surrounds the periphery of the lower arm 8 located inside the machining tank 6. The machining tank 6 has an opening 60 through which the lower arm 8 passes. The bellows member 11 is disposed so that an opening at one end of the cylindrical ends is closed and the other end surrounds the periphery of the opening 60 of the machining tank 6, and closes the gap between the cylindrical interior of the bellows member 11 and the interior of the machining tank 6 in which the machining fluid is stored, so that the machining fluid does not leak from inside the machining tank 6 even if the relative positions of the lower wire guide 10 and the machining tank 6 change. That is, since the lower arm 8 is surrounded by the bellows member 11, it is not immersed in the machining fluid and is not affected by the temperature of the machining fluid in the machining tank 6.

[0029] Therefore, the wire electric discharge machine 100 according to the present embodiment can suppress the thermal expansion of the lower arm 8, and therefore can suppress deterioration of the machining accuracy of the workpiece W. Furthermore, since no machining chips are accumulated in the grooves on the inner surface of the bellows member 11, it is possible to avoid the accumulation of machining chips in the grooves hindering the expansion and contraction of the bellows member 11, and it is possible to prevent a decrease in the positional accuracy of the wire electrode 7 relative to the workpiece W. Therefore, the wire electric discharge machine 100 can suppress deterioration of the machining accuracy of the workpiece W caused by the machining chips. It is considered that machining chips are accumulated in the grooves on the outer surface of the bellows member 11. However, inside the machining tank 6, the machining fluid flows due to repeated inflow and outflow. That is, even if the machining chips generated by wire electric discharge machining reach the outer surface of the bellows member 11, they are swept away by the flow of the machining fluid to other locations, and therefore do not become a load for the expansion and contraction of the bellows member 11.

[0030] FIG. 14 is an explanatory diagram showing an example of a lower arm and a bellows member in a wire electric discharge machine of a comparative example. FIG. 15 is an explanatory diagram showing a state in which the bellows member is expanded or contracted along the X-axis direction from the state shown in FIG. 14 in a wire electric discharge machine of a comparative example. The bellows member 11 is disposed inside the machining tank 6 filled with machining fluid, and therefore may sag downward due to its own weight and the hydraulic pressure of the machining fluid. If the bellows member 11 sags and deforms, it may not be able to expand or contract in response to the movement of the machining tank 6. Therefore, the bellows member 11 is held on the upper surface of the lower arm 8 so as not to sag. However, for example, as shown in FIG. 14, if the vertical section of the lower arm 8A is circular, the contact area between the outer surface of the lower arm 8A and the inner surface of the bellows member 11 is small, and the range in which the bellows member 11 is held by the lower arm 8A is small. 15, when the bellows member 11 expands and contracts along the X-axis direction and the lower arm 8A reaches one of the inner surfaces of the bellows member 11, the distance from the contact point between the lower arm 8A and the bellows member 11 to the other inner surface of the bellows member 11 increases. In this case, the bellows member 11 hangs down due to a large load caused by its own weight and the hydraulic pressure of the machining fluid acting on the other side surface.

[0031] 7, the lower arm 8 in this embodiment has a rectangular cross-sectional shape and a flat upper surface. The bellows member 11 has a rectangular tubular shape and has a flat surface facing the flat upper surface of the lower arm 8. This allows the upper surface of the lower arm 8 and the flat surface of the bellows member 11 to be in surface contact with each other, and the range in which the lower arm 8 holds the bellows member 11 is increased.

[0032] Fig. 16 is an explanatory diagram showing a wire electric discharge machine according to the embodiment in a state where the bellows member expands and contracts along the X-axis direction from the state shown in Fig. 7. As shown in Fig. 16, even if the bellows member 11 expands and contracts along the X-axis direction and the lower arm 8 reaches one inner side surface of the bellows member 11, the distance from the position where the lower arm 8 and the bellows member 11 make surface contact with each other to the other inner side surface of the bellows member 11 can be small. That is, the wire electric discharge machine 100 according to the present embodiment can suppress sagging of the bellows member 11 due to its own weight and the hydraulic pressure of the machining fluid.

[0033] The vertical cross-sectional shape of the lower arm 8 is not limited to being rectangular. The lower arm 8 may have another shape as long as it has a flat upper surface. The bellows member 11 is not limited to being rectangular tubular. The bellows member 11 may have another shape as long as it has a flat surface facing the flat upper surface of the lower arm 8.

[0034] In the present embodiment, the Y-axis table 3 and the X-axis table 4 are used to move the machining tank 6 in the X-axis and Y-axis directions to machine the workpiece W, but the present invention is not limited to this configuration. For example, the Y-axis table 3 and the X-axis table 4 may be installed at the lower end of the column 2. In this case, the column 2 moves in the X-axis and Y-axis directions to move the wire electrode 7 in the X-axis and Y-axis directions, thereby machining the workpiece W. In addition, one of the Y-axis table 3 and the X-axis table 4 may be installed below the machining tank 6, and the other may be installed below the column 2.

[0035] The configurations shown in the above embodiments are merely examples, and may be combined with other known technologies. Parts of the configurations may be omitted or modified without departing from the spirit of the invention. [Explanation of symbols]

[0036] 1 bed, 2 column, 3 Y-axis table, 4 X-axis table, 5 Z-axis base, 6 machining tank, 7 wire electrode, 8, 8A lower arm, 9 upper wire guide, 10 lower wire guide, 10a holding portion, 10b insulating member, 10c intermediate member, 10d, 10e flange portion, 11, 12 bellows member, 11a main body portion, 11b first connection portion, 11c second connection portion, 13, 14, 15, 16 fixing member, 17, 18, 19 sealing member, 60 opening, 100, 100A wire electric discharge machine, W workpiece.

Claims

1. a machining tank in which a machining fluid is stored; a wire electrode for generating an electric discharge between the wire electrode and a workpiece immersed in the machining fluid in the machining tank, thereby performing electric discharge machining on the workpiece; a lower arm extending from the inside to the outside of the processing tank; a lower wire guide attached to the lower arm and disposed inside the machining tank, the lower wire guide holding the wire electrode; a cylindrical bellows member that is disposed inside the processing tank and surrounds the lower arm located inside the processing tank, The processing tank has an opening through which the lower arm passes, The bellows member has an opening at one end of its cylindrical shape that is closed, and the other end is arranged to surround the periphery of the opening of the machining tank and is connected to the inner surface of the machining tank, and closes the space between the cylindrical interior of the bellows member and the interior of the machining tank where the machining fluid is stored so that the machining fluid will not leak from inside the machining tank even if the relative position of the lower wire guide and the machining tank changes. A wire electric discharge machine characterized by:

2. The bellows member is a cylindrical main body having a bellows structure; a first connection portion provided at one end of the main body portion; a second connection portion provided at the other end of the main body portion, The bellows member has the first connecting portion attached to the lower wire guide to close an opening at one end thereof, and the second connecting portion attached to the machining tank so as to surround the periphery of the opening of the machining tank, thereby closing the gap between the cylindrical interior of the bellows member and the interior of the machining tank in which machining fluid is stored.

2. The wire electric discharge machine according to claim 1.

3. The lower wire guide a holder for holding the wire electrode; an insulating member attached to the lower arm and insulating between the holding portion and the lower arm; a cylindrical intermediate member attached to the insulating member and through which the lower arm passes, The bellows member has the first connection portion connected to the intermediate member and an opening provided at one end thereof closed by the insulating member.

3. The wire electric discharge machine according to claim 2.

4. the lower arm has a planar upper surface; The bellows member has a flat surface facing the flat upper surface of the lower arm.

4. The wire electric discharge machine according to claim 1, wherein the wire electric discharge machine is a wire-cut electric discharge machine.

5. The lower arm has a rectangular cross section, The bellows member has a rectangular cylindrical shape.

5. The wire electric discharge machine according to claim 4.

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