JPH038892B2 - - Google Patents

Description

Detailed Description of the Invention "Industrial Application Field" The present invention involves immersing a workpiece in a machining liquid and inserting a wire electrode through the workpiece.
The present invention relates to a wire-cut electrical discharge machine that performs electrical discharge machining by moving relative to the workpiece while generating electrical discharge between the workpiece and the wire electrode.

"Conventional technology" In a wire-cut electric discharge machine, machining is performed by moving the workpiece and the wire electrode relative to each other, so machining fluid flows out from the insertion hole for inserting the wire electrode in the machining tank. So,
In order to prevent air discharge in the wire electrode, it has been difficult to control the level of the machining fluid. Tokukai Akira
Publication No. 55-157433 discloses, in an electric discharge machine equipped with a pair of upper and lower wire electrode guides arranged to sandwich the upper and lower parts of the workpiece outside the machining tank, a wire electrode guide disposed between the workpiece and the lower wire electrode guide. As described above, an invention has been disclosed that aims to reduce the amount of machining fluid flowing out by attaching a plate-shaped machining fluid receiving member that slides on the bottom surface of the machining tank to the electrode guide. There was a problem that the amount of processing fluid flowing out was relatively large. For this reason,
In the applicant's previous application (Japanese Patent Application No. 59-39075), a long hole extending horizontally is formed in the side wall of the processing tank, and guide grooves are provided in the side wall along the top and bottom of the long hole. An electric discharge machine has been proposed in which leakage of machining fluid is prevented by a shield that is slidably supported by a shield. However, a flexible band-shaped body such as a steel seal shield has a cross section that is curved in advance so as to be concave toward the take-up roller. When this shield is wrapped around the take-up roller, the curved shape is deformed into a straight line, so the extended end pulled out from the take-up roller will wrap around the take-up roller due to its own elasticity. There is. This property is a technology that has been used for a long time in steel plate tape measures and the like, and is commercially available as "Conston for Covers" (registered trademark), for example. A conventional wire-cut electric discharge machine utilizes the property that a shield wraps around a take-up roller. However, in conventional wire-cut electric discharge machines, a method has been adopted in which the shield 32 is mounted with the surface to be wound around the take-up roller 29 facing inside the machining tank 2, as shown in FIG. 7a. With this method, when the machining tank 2 is filled with machining liquid as shown in FIG. 7b, the shielding body 32 is further bent toward the outside of the machining tank 2 due to the liquid pressure.

The upper and lower edges of the shield 32 are guided by narrow guide grooves, and the guide groove includes a packing 40 on the outside of the machining tank 2, so that the shield 32 does not bend to the outside of the machining groove 2. Therefore, the shielding body 32 is strongly pressed against the packing 40, and the frictional resistance between the two increases, causing a problem that the accuracy of movement of the X-Y table in the X direction shown in FIG. 7a is impaired. Ta.

"Problems to be Solved by the Invention" The present invention has been made to solve the above-mentioned problems, and aims to reduce the frictional resistance of the seal portion of the processing tank.

"Means for Solving the Problems" According to the present invention, as shown in FIGS. 1 to 5, a processing tank 2 in which a workpiece W can be immersed
A long hole 21 extending horizontally is formed in the side wall of the
It is slidably supported via a packing 40 in a guide groove 27 provided in the side wall along the upper and lower sides of the elongated hole 21, and has a curved cross section in advance so that the surface to be wound around the winding portion 29 is concave. In a wire cut electrical discharge machine having a flexible strip-shaped shield 32 formed in the winding portion 2, the shield 32 is
By directing the surface of the shield 32 toward the outside of the processing tank 2, the central part in the width direction is curved and protrudes toward the processing tank 2 from both side edges and is supported by the guide groove 27. A wire cut electric discharge machine is provided in which the winding portion 29 is supported by the side wall of the machining tank 2 on both sides of the elongated hole 21.

"Function" According to the above configuration, the present invention reverses the arrangement of the shield 32 and makes the shield 32 curvedly protrude toward the processing tank 2 side from both side edges at the center in the width direction so as to fit into the guide groove 27. Because it supports, the hydraulic pressure F of the machining fluid L
When the shield 32 is deflected to the outside of the processing tank 2,
As shown in FIG. 5, the shielding body 32 is deformed flat by the hydraulic pressure, and the pressure of the shielding body 32 against the packing 40 in the guide groove 27 is reduced, which is advantageous in that the frictional resistance between the two is reduced. It has other effects. This effect of the present invention is as shown in the characteristic diagram of FIG. 6. According to the embodiment of the present invention, at a water level of 200 mm, the frictional resistance was reduced to about 1 Kgf compared to the conventional 5 Kgf.

"Embodiment" Hereinafter, one embodiment of the present invention will be described in detail with reference to the drawings.

Now, to explain the overall configuration of the wire cut electric discharge machine of this embodiment, as shown in FIG.
It is arranged so as to be relatively movable in the horizontal direction back and forth and left and right, and can support the workpiece W in a state where the inside thereof is filled with the machining fluid L. An upper arm 3 is attached to the frame 1 above the processing tank 2.
is provided, and an upper electrode guide 4 made of a conductive roller is supported at the bottom thereof so as to be movable in the vertical direction. A lower arm 5 made of a conductive cylindrical body is insulated from the frame 1 on the side of the frame 1 so as to penetrate the side wall of the processing tank 2 and extend horizontally to a position below the workpiece W. A lower electrode guide 6 made of a conductive roller is supported at the tip of the lower electrode guide 6 while being insulated from the lower arm 5 .

A feeding device 8 for feeding a wire electrode 7 made of a metal wire is provided at the top of the frame 1, and a winding device 9 for winding up the wire electrode 7 is provided at the bottom of the frame 1. . Then, the wire electrode 7 fed out from the supply device 8 is guided to the winding device 9 through the guide roller 10, the upper electrode guide 4, the lower electrode guide 6, and the guide roller 11, and is wrapped between the electrode guides 4 and 6. It is adapted to be continuously supplied onto the workpiece W.

A power supply circuit is connected between the wire electrode 7 and the workpiece W, and a pulse discharge is repeatedly generated in the machining gap between the wire electrode 7 and the workpiece W, and the workpiece W is machined by the discharge energy. It's summery. That is, in the power supply circuit, the DC power supply 1
A source terminal of a field effect transistor 13 is connected to one terminal of the transistor 2, and a switching control circuit 14 for controlling the switching operation of the transistor 13 is connected to its gate terminal.
The transistor 1 is connected between the drain terminal of the field effect transistor 13 and the other terminal of the power supply 12.
A diode 15 and a resistor 16 are connected to eliminate the reactance voltage generated with the switching operation of step 3. And the workpiece W
is connected to the ground side terminal of the power supply circuit via the conductive lower arm 5, and the wire electrode 7 is connected to the other terminal of the power supply circuit via the lower electrode guide 6.

Further, a pump 17 is connected to the lower arm 5, and the operation of this pump 17 fills the machining fluid L from the machining fluid tank 18 through the inside of the lower arm 5 into the machining tank 2 at the start of work, and fills the machining fluid L into the machining tank 2 during machining work. Inside, the machining liquid L can be supplied to the machining gap between the wire electrode 7 and the workpiece W.

Next, regarding the seal configuration between the long hole and the shield in the processing tank 2, which is the main part of the present invention, the second to
This will be explained in detail based on FIG.

In this embodiment, a long hole 21 for inserting the lower arm 5 is formed near the lower end of the side wall of the processing tank 2 so as to extend substantially horizontally. Steel housings 25 forming winding portions are provided on the outer surfaces of the side walls of the processing tank 2 on both sides. long hole 2
A groove 23 for catching leakage water from the processing tank 2 is formed on the upper surface of the bottom wall of the processing tank 2 so as to extend along the elongated hole 21 on the outside of the processing tank 1, and communicates with one end of the groove 23. A water drain port 24 is formed in the side wall of the processing tank 2.

A pair of upper and lower press plates 28 are hung between both steel housings 25 attached to the outer surface of the side wall of the processing tank 2 on both sides of the elongated hole 21, and an opening 26 is formed corresponding to the elongated hole 21. There is. As shown in FIGS. 4 and 5, a pair of guide grooves 2 are formed on the outer surface of the side wall of the processing tank 2 by means of the holding plate 28, which extend horizontally along the top and bottom of the elongated hole 21.
7 is formed.

As shown in FIG. 3, a housing recess 22 is formed inside the steel housing 25.
A cylindrical winding roller 29 is disposed in the housing recess 22.
is rotatably supported. In this embodiment, the upper and lower rotating shafts 31 of the winding roller 29
is supported by the lower and upper walls of the housing recess 22 in the steel housing 25, and as shown in FIG. Housing bush 3
0 is inserted.

A steel seal 32 forming a flexible band-like shield is wound around and supported by the winding rollers 29 at both left and right ends, and the intermediate portion of the steel seal 32 is connected to the processing tank. The guide groove 27 is slidably inserted and supported within the guide groove 27 formed by the outer surface of the side wall 2 and the step portion 41 of the upper and lower presser plates 28 . Note that, as shown in FIG. 2, a packing 40 is attached to the side wall of the stepped portion 41. A seal receiver 34 made of flexible synthetic resin is provided in a through hole 33 formed approximately in the center of the steel seal 32.
A is fitted, and the seal receiver 34B is fitted to the outer end of the seal receiver 34A by sandwiching the steel seal 32, and a plurality of screws 36 are inserted into the seal receiver 34B.
By screwing in the seal receivers 34A and 34B,
is fixed to the periphery of the through hole 33. Seal receiver 3
Fitting holes 35 and 37 for slidably fitting the lower arm 5 are formed in the centers of 4A and 34B,
On the inner periphery of the fitting hole 35, an annular pipe seal 38 made of an air-impermeable closed-cell foam material is provided that is in close contact with the outer peripheral surface of the lower arm 5. In addition, in FIG. 2, the pipe seal 38 is shown taken out from the fitting hole 35.

In this embodiment, as shown in FIG. 3, the winding roller 29 forming the winding section is
It is located outside. And steel seal 3
2 is arranged such that the surface thereof to be wound around a winding roller 29 faces the outside of the processing tank 2. With this configuration, the steel seal 32 is supported in a curved manner inwardly of the processing tank 2 at its center in the width direction, as shown by the two-dot chain line in FIG. Further, in this embodiment, the surface of the steel seal 32 to be wound around the winding roller 29 is concave so that the steel seal 32 has the property of being wound around the winding roller 29 forming the winding part by its own elastic force. The cross section is previously formed into a curved shape. and,
When the steel seal 32 is moved relative to the processing tank 2, one winding portion is unwound, and the other winding portion is wound by its own elastic force.

In the above configuration, in order to attach the steel seal 32 to the processing tank 2, as shown in FIG.
4B toward the machining tank 2 side, then pass the tip of the lower arm 5 through the through hole 33 of the steel seal 32, and finally insert the seal receiver 34A with the integrated pipe seal 38 into the machining tank 2. The lower arm 5 is inserted into the lower arm 5 toward the outside. Then, as shown in FIG. 4, the tip of the inner seal receiver 34A is inserted through the steel seal 32 and assembled into the inner diameter recess of the outer seal receiver 34B.
Both seal receivers 34A and 34B are tightened and fixed to the steel seal 32 by the following steps. Further, the upper and lower presser plates 28, which are integrally fixed to the left and right steel housings 25 by screws (not shown), are attached to the outer surface of the outer wall of the processing tank 2 by a large number of screws 39, as shown in FIGS. 2, 3, and 4. It is skewered so that it can be eaten.

When the machining tank 2 is filled with the machining fluid L and electrical discharge machining is performed, when the lower arm 5 is relatively moved in the X direction in FIG. 3 as the machining tank 2 moves in the horizontal direction, the steel seal 32 is also moved in the same direction and is wound up or rewound by the winding rollers 29 in the steel housings 25 at both ends.

At this time, as shown by the solid line in FIG. 5, the warpage of the steel seal 32 is reduced by the water pressure F caused by the machining liquid L in the machining tank 2, and the steel seal 32 becomes substantially flat, so that the outer surface of the side wall of the machining tank 2 Alternatively, since the frictional force with the inner surface of the holding plate 28 is reduced, the steel seal 32 slides very easily in the guide groove 27 as the lower arm 5 moves relative to the X direction. A small amount of machining fluid leaking from the machining tank 2 through the gap between the guide groove 27 and the steel seal 32 is collected by the groove portion 23 and returned to the machining fluid tank 18 through the drain port 24.

Further, when the lower arm 5 moves in the Y direction, the lower arm 5 is slid along the fitting hole 35 of the seal receiver 34A on the steel seal 32,
The pipe seal 38 maintains a sealed state.

(Numerical Performance Example) Regarding the frictional resistance of the steel seal 32 within the guide groove 27, a performance example of this embodiment is shown in FIG. 6 in comparison with a conventional configuration. As shown in Figure 6, in the conventional configuration, when the water level of the machining fluid in the machining tank is gradually raised from a dry state to a wet state, the frictional resistance of the steel seal increases, and at a water level of 200 mm, the frictional resistance is approximately 5 kgf. It was hot, but
According to the example of the present invention, the frictional resistance did not increase even as the water level rose, and the frictional resistance at a water level of 200 mm was about 1 Kgf. Therefore, the effect of this embodiment is extremely significant.

"Other Embodiments" In the above embodiments, the shield that forms the seal for the elongated hole 21 formed in the side wall of the processing tank 2 is composed of the steel seal 32 made of steel. It would also have been possible to replace it with a band-like member having flexibility. Moreover, the present invention
It is important that the warpage of the steel seal 32 and other shielding bodies curve into the processing tank 2. Also in the present invention, the winding portion 29 can be provided inside the processing tank 2, as in the prior art shown in FIG.
However, in the case of the present invention, it is necessary to turn the winding part 29 back and forth so that the surface of the shield 32 wound around the winding part 29 faces the outside of the processing tank 2.

[Effects] As described above, since the electric discharge machine of the present invention has the above configuration, it is possible to reliably prevent machining fluid from leaking from inside the machining tank, and also to prevent the machining fluid from leaking from the machining tank. The frictional resistance with the shield can be reduced, and the motion accuracy of the X-Y table can be maintained well, resulting in excellent effects such as improved electrical discharge machining accuracy.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing the overall configuration of an embodiment of the present invention, Fig. 2 is an exploded perspective view of a sealing part that constitutes the main part of the embodiment, Fig. 3 is a cross-sectional view of the sealing part, and Fig. 4 is a cross-sectional view of the sealing part. The figure is a longitudinal sectional view, Fig. 5 is a longitudinal sectional view showing the installed state of the steel seal, Fig. 6 is a characteristic diagram showing numerical performance examples, and Fig. 7 a and b are cross-sectional views and longitudinal sections showing the conventional configuration. It is a front view. DESCRIPTION OF SYMBOLS 1... Frame, 2... Processing tank, 21... Long hole, 25... Steel housing, 27... Guide groove, 29... Winding roller, 32... Steel seal, 40... Packing. W... Workpiece, L...
Processing fluid.

Claims (1)

[Claims] 1. A long hole extending horizontally is formed in the side wall of a processing tank in which the workpiece can be immersed, and a gasket is inserted into a guide groove provided in the side wall along the top and bottom of the long hole. A wire-cut electric discharge machine having a flexible band-shaped shield that is slidably supported and has a curved cross section in advance so that the surface to be wound around the winding portion is concave, By directing the surface wound around the winding portion toward the outside of the processing tank, the shield is curved and protrudes toward the processing tank at its center in the width direction beyond its both side edges, and is supported by the guide groove. A wire-cut electric discharge machine characterized in that the winding portion of the body is supported by the side wall of the machining tank on both sides of the elongated hole.