JPH09314421A - Method for machining curved hole by electric discharge machining and system for the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make a small curved hole accurately by miniaturizing the machin ing portion. SOLUTION: In the method of machining a small curved hole employing the electric charging method between the electrode 32 and a work W and to machine a hole wr, a curved tube 34 which is adapted to bend in accordance with the hole wr provides the electrode 32 at its distal end rockably, and by tilting the work W in direction of predetermined way, and transferring the tube 34, the electrode 34 advances in direction of gravity and contacts with the surface of work W, and a space adjusting means control tone distance between the electrode 32 and the work surface. Thereby, the linking system for moving the electrode 32 in three dimensional direction is eliminated, and so the machining section for the curved hole wr is miniaturized, and further, so far the electrode 32 is defined to move always in direction of gravity, the position of distal end of the electrode 32 can be secured and the accuracy of machining the curved hole wr is promoted.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for forming a curved hole in a workpiece by utilizing electric discharge between an electrode and the workpiece.

[0002]

2. Description of the Related Art A conventional curved hole drilling apparatus relating to this is described in the electrical machining technology Vol. 12 No. 38 1988, and its schematic diagram is shown in FIG. As shown in FIG. 7 (A), the curved hole machining apparatus 1 includes a joint mechanism 2 in which a plurality of cylindrical joint pieces are connected in a universal joint shape.
The joint mechanism 2 has an electrode 3 for electrical discharge machining attached to the tip thereof. When processing the curved hole wr in the workpiece w, as shown in FIG. 7B, the joint mechanism 2 is remotely operated to match the electrode 3 with the hole machining shape.
EDM is performed while moving the. This makes it possible to machine the three-dimensional curved hole wr in the workpiece w.

[0003]

However, since the curved hole machining device 1 includes the complicated joint mechanism 2, it is difficult to downsize the device and the diameter of the curved hole that can be machined is limited. There is. Further, depending on the shape of the bent hole, the middle portion of the joint mechanism 2 is twisted, so that the movement of the joint mechanism 2 becomes stiff and the tip position and direction of the electrode 3 cannot be grasped with high accuracy. The technical problem of the present invention is to make it possible to move an electrode three-dimensionally with respect to a work piece without using a joint mechanism, thereby achieving miniaturization of an electrode supporting portion of the device and bending of a small diameter. Even holes can be processed with high precision.

[0004]

The above-mentioned problems can be solved by a curved hole machining method by electric discharge machining having the following features. That is, the invention according to claim 1 is a method for machining a bent hole in a workpiece by using an electric discharge between an electrode and the workpiece, wherein the tip of the tube bent along the bent hole The electrode is suspended so that it can swing, the workpiece is tilted in a predetermined direction, the tube is fed to advance the electrode in the direction of gravity, and the gap between the electrode and the machining surface is adjusted by the gap adjusting means. Is adjusted to a dischargeable interval. That is, since the method of performing electric discharge machining by always advancing the electrode in the direction of gravity while inclining the workpiece, a joint mechanism for moving the electrode three-dimensionally is not required, and a portion for forming a curved hole is eliminated. Miniaturization is possible. Therefore, a bent hole having a small diameter can be formed. Further, since the electrode always advances in the direction of gravity, the tip position and direction of the electrode can be accurately grasped, and the accuracy of processing the curved hole is improved.

According to a second aspect of the present invention, in a device for machining a bent hole in a work by utilizing an electric discharge between an electrode and the work, a tube that bends following the bent hole is provided. A tube feed means for feeding the tube into the bent hole, an electrode oscillatingly suspended at the tip of the tube, an inclination adjusting means for adjusting the inclination of the workpiece, the electrode and the workpiece And a space adjusting means for adjusting the space between the machined surface and the surface to be discharged. Therefore, the invention according to claim 1 can be implemented by this bent hole machining device.

The invention described in claim 3 is the same as claim 2
In the curved hole machining apparatus by electric discharge machining described in, the gap adjusting mechanism is arranged so as to face the back surface of the electrode at the tip position of the tube and the amount of the machining fluid ejected from the ejection port formed at the tip position of the tube. The distance between the electrode and the processed surface of the workpiece is adjusted by adjusting the amount of the processing liquid sucked from the suction port formed as described above. Therefore, it is not necessary to provide a mechanical electrode positioning mechanism at the tip of the tube, the structure is simplified and the device is made compact.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION

[First Embodiment] Hereinafter, a curved hole machining method and device using electric discharge machining according to an embodiment of the present invention will be described with reference to FIGS. 1 to 7. Here, FIG. 1 is an overall schematic view of a curved hole machining apparatus by electric discharge machining according to the present embodiment, and FIG. 2 is a detailed view of a II portion of FIG. Further, FIG. 3 is a side view showing a curved hole machining method by electric discharge machining, FIG. 4 is a flow chart showing a curved hole machining method by electric discharge machining, and FIG. 5 is a schematic diagram showing a shape of a center line of a curved hole to be machined. is there. In addition, in FIG. 1, the horizontal direction is X.
The following description will be given with the axial direction, the direction perpendicular to the paper surface as the Y-axis direction and the height direction as the Z-axis direction.

The curved hole machining device 10 is a device for machining a curved hole wr in the workpiece w by utilizing the electric discharge between the electrode 32 and the workpiece w, and supplies electric power for electric discharge machining. Power supply device 11, a tilt adjustment device 20 that adjusts the tilt of the workpiece w according to the shape of the bent hole and the position of the electrode, and an electrode position control device 30 that controls the tip position of the electrode 32. Has been done. Power supply device 11
Includes a main control panel 14 that monitors and controls electric discharge machining, and a power supply panel 16 that supplies power to the electrodes 32 based on a signal from the main control panel 14, and the power supply panel 16 and the electrodes 32 and The power supply board 16 and the workpiece w are connected by a current supply cord 14k. Then, when the distance between the electrode 32 and the machined surface of the workpiece w is within a predetermined range, electric discharge is performed between the both 32 and w, and the machined surface of the workpiece w is electric discharge machined.

The tilt adjusting device 20 is a device for adjusting the tilt of the workpiece w, as described above, and is provided on the base 22 with Y.
It is provided with a pair of bearing mounts 23 fixed in the axial direction. The bearing pedestal 23 is a pedestal that supports the outer ring pedestal 24 so as to be rotatable about the Y axis.
A pair of pins 24p fixed in the radial direction on the outer peripheral surface of the outer ring mount 24 is inserted into the bearing holes 23k of the third ring. The outer ring pedestal 24 is a pedestal that rotatably supports an inner ring pedestal 25 (see the dotted line in the figure) positioned coaxially so as to be rotatable around an axis orthogonal to the Y axis, and rotated by 90 ° from the position of the pin 24p. The position is provided with a pair of bearing holes 24k. A pair of pins 25p fixed in the outer peripheral surface of the inner ring mount 25 in the radial direction are inserted into the bearing holes 24k.

The inner ring pedestal 25 is a pedestal for supporting the workpiece w, and a gripping mechanism (not shown) for gripping the workpiece w is mounted inside thereof. With this structure, the workpiece w held by the inner ring mount 25 can be tilted about the Y axis or about an axis orthogonal to the Y axis. A first servomotor 26 for rotating the outer ring mount 24 around the Y axis is installed on the base 22, and the inner ring mount 25 is attached to the outer ring mount 24 so as to be orthogonal to the Y axis. Second servo motor 27 for rotating around
Is installed. Then, the first servo motor 26
The second servo motor 27 is controlled based on the signal from the tilt control board 50. The tilt control board 50 is configured to perform the first
The servo motor 26 and the like are controlled, and the feeding amounts of the tube 34 and the electrode 32, which will be described later, are controlled.

The electrode position control device 30 has a curved hole w.
Tube 3 that is inserted into r and sends the electrode 32 to the processing position
4, a tube feed mechanism 36 that feeds the tube 34 into the bent hole wr, and a working liquid supply mechanism 38 that supplies the working liquid to the working portion and adjusts the distance between the electrode 32 and the working surface. The tube 34 has flexibility so that it can be bent following the bent hole wr, and a current supply cord 14k for supplying a current to the electrode 32 is positioned at the axial center portion of the tube 34. Here, the current supply cord 14k is constrained only at the tip portion of the tube 34, and is not constrained at other portions. Therefore, the current supply cord 14k does not hinder the bending of the tube 34.

Further, as shown in FIG. 2 (A), inside the tube 34, a supply passage 34a for supplying the machining fluid to the electric discharge machining site and a collection of the machining fluid from the bending hole wr. And a recovery passage 34b of the same. The opening 34d of the recovery passage 34b is shown in FIG.
As shown in (B), the tubes 34 are radially arranged at the central portion of the tip of the tube 34. In addition, the supply passage 3
The opening 34c of 4a is arranged around the opening 34d of the recovery passage 34b. Therefore, the working liquid flows from the outer peripheral portion toward the central portion.

Further, at the center of the tip of the tube 34, a flange-shaped hook 34f (see FIG. 2) connected to the tip of the current supply cord 14k is swingably connected by a universal joint U. 34
An electrode 32 is suspended on f. Further, an inner diameter guarantee ring 34r having an outer diameter substantially equal to the inner diameter of the bent hole wr is fixed to the outer periphery of the distal end portion of the tube 34. For this reason, when the inner diameter of the bent hole wr formed by the consumption of the electrode 32 becomes small, the tube 34 cannot enter the bent hole wr, and the electric discharge machining is stopped.

In the electrode 32, the tip of a short cylinder is processed into a spherical shape, and copper tungsten or the like, which is hard to wear, is used as its material. An engaging member 32k that engages with a hook 34f connected to the tube 34 is fixed to the center of the upper surface (back surface) of the electrode 32. The engaging member 3
2k is provided with a ring-shaped step 32r at the upper end of a cylindrical body 32t, and the step 32r is adapted to engage with a flange-shaped hook 34f. For this reason, as shown in FIG.
If no upward force is applied to the hook, the weight of the electrode 32 causes the hook 34f and the step 32r to come into contact with each other, and the distal end surface of the tube 34 and the upper surface of the electrode 32 are most distant from each other, and the value is maintained at the dimension d. To be done. On the contrary, when an upward force is applied to the electrode 32, the electrode 32 can be displaced upward from this position by the height of the cylindrical body 32t.

As shown in FIG. 1, the tube feed mechanism 36 has a portal frame 36m attached to the upper surface wu of the workpiece w, and the tubes 34 are mounted on both columns of the portal frame 36m. A feed roller 36r for feeding along the column is attached. The roller 36r is driven by a feed servo motor (not shown), and the feed servo motor is controlled based on a signal from the tilt control board 50. Further, a feed detection sensor 36s for detecting the feed amount of the current supply cord 14k is mounted on the ceiling portion of the portal frame 36m. A detection signal from the feed detection sensor 36s is input to the tilt control board 50. Here, current supply cord 14k
As described above, since the tube is constrained only at the distal end portion of the tube 34, it is possible to accurately grasp the feed amount of the tube 34 without being affected by the twist of the tube 34 and the like.

A supply pipe 38a and a recovery pipe 38b of a working liquid supply device 38 are connected to the base end of the tube 34. The supply pipe 38a is a pipe that connects the supply passage 34a of the tube 34 and the machining fluid tank 38t, and in the middle thereof, the machining fluid is supplied, that is, the machining fluid is ejected from the opening 34c of the supply passage 34a. A first adjusting mechanism 38e for adjusting is attached. Further, the recovery pipe 38b is a pipe that connects the recovery passage 34b of the tube 34 and the working fluid tank 38t, and in the middle thereof, the amount of working fluid recovered, that is, the recovery passage 34.
A second adjusting mechanism 38f for adjusting the suction amount of the processing liquid from the opening 34d of b is mounted. The first adjusting mechanism 38e and the second adjusting mechanism 38f are driven based on a control signal from the main control panel 14.

As shown in FIG. 3A, when the electrode 32 is accommodated in the curved hole wr, the flow rate of the working fluid is sucked by the first adjusting mechanism 38e and the second adjusting mechanism 38f. When the ejection amount is adjusted, the electrode 32 is attracted to the tip of the tube 34 and rises to the position of the alternate long and short dash line in FIG. 2A (upper limit lock position). On the contrary, when the flow rate of the working fluid is adjusted to the suction amount << the ejection amount, the electrode 32 is pressed by the working fluid and descends to the position (lower limit position) indicated by the solid line in FIG. Further, when the flow rate of the working fluid is adjusted to the suction amount = the ejection amount, the electrode 32 descends in the working fluid by its own weight without receiving the pressing force or the suction force of the working fluid. Further, by adjusting the pressing force and the suction force to the electrode 32 while adjusting the suction amount and the ejection amount, the electrode 32 is moved up and down between the lower limit position and the upper limit position to process the electrode 32 and the workpiece w. You will be able to adjust the distance to the surface. That is, the supply pipe 38
a, the recovery pipe 38b, the first adjusting mechanism 38e, the second adjusting mechanism 38f, and the main control panel 14 function as the interval adjusting means of the present invention.

Next, a method for forming a curved hole according to this embodiment will be described with reference to FIGS. 3, 4, and 5. First, the workpiece w is the inner ring mount 2 of the tilt adjusting device 20.
5, the gate-shaped mount 36m of the tube feed mechanism 36 is fixed to a predetermined position on the upper surface wu of the workpiece w. Here, as shown in FIGS. 3 (A) to 3 (C), in the case of drilling vertically, the tilt control board 50 drives the first servo motor 26 and the second servo motor 27 to process the workpiece. The object w is positioned vertically. Next, the main control panel 14
The power supply board 16 is controlled on the basis of the signal from, and a predetermined pulse voltage is applied between the electrode 32 and the workpiece w (step 101 in FIG. 4). Furthermore, the first control mechanism 38e and the second adjustment mechanism 38f are controlled by the main control board 14 so that the working fluid is adjusted so that the ejection amount << the suction amount, and the electrode 32 is sucked by the tip end surface of the tube 34 and the upper limit is reached. Ascend to the lock position (steps 102 and 103).

Next, the working liquid is adjusted so that the ejection amount = the suction amount, so that the electrode 32 naturally descends (steps 104 and 105). Then, it is determined whether or not a current flows between the electrode 32 and the workpiece w in the process of descending the electrode 32 (step 106). When the current does not flow, the distance between the electrode 32 and the workpiece w may be too large. Therefore, the center of the spherical portion of the electrode 32 (hereinafter referred to as the tip center) is at the command position. It is determined whether or not (step 107). And
If the center of the tip of the electrode 32 is not at the command position, the tube 34 is fed by a certain amount by the feed roller 36r (step 108, see FIG. 3A). As a result, the electrode 32 comes into contact with the processed surface of the workpiece w.

Then, again from step 102 to step 1
When the process up to 06 is executed and a current flows between the electrode 32 and the workpiece w (step 106 YES), it is determined whether the no-load voltage application time is shorter than the reference time (step 109). ). When the no-load voltage application time is shorter than the reference time, the distance between the electrode 32 and the machining surface of the workpiece w is narrow, and therefore the machining fluid is adjusted to the suction amount> the ejection amount (step 110). As a result, the electrode 32 is attracted to the tip end surface of the tube 34 and displaced upward, and the gap between the electrode 32 and the processed surface of the workpiece w becomes wider. If the no-load voltage application time is longer than the reference time,
Since the distance between the electrode 32 and the machined surface of the workpiece w is wide, the machining liquid is adjusted so that the suction amount is smaller than the ejection amount (step 11).
2). As a result, the electrode 32 separates from the tip surface of the tube 34, and the electrode 32 comes closer to the processed surface of the workpiece w. That is, the gap between the electrode 32 and the machined surface of the workpiece w is maintained at an appropriate value, and the electric discharge machining is favorably performed (see FIG. 3B).

Since the distance between the electrode 32 and the machined surface of the workpiece w is maintained at an appropriate value in this way, when the machined surface of the workpiece w is gradually shaved by electrical discharge machining, Accordingly, the electrode 32 also gradually descends. Then, the electrode 32 reaches the position farthest from the tip surface of the tube 34, that is, reaches the lower limit position of the dimension d from the tip surface, and the distance between the electrode 32 and the processed surface of the workpiece w is a dischargeable interval. When it becomes wider than that, the discharge automatically stops (see FIG. 3C). When it is determined in step 114 that no current flows between the electrode 32 and the workpiece w, the processes of steps 102 to 107 are executed again, and the tip center of the electrode 32 is not at the command position ( Step 107 NO), the tube 34 is moved by the feed roller 36r
Then, a fixed amount is fed by (step 108, see FIG. 3A). As a result, the electrode 32 comes into contact with the processed surface of the workpiece w.

When the center of the tip of the electrode 32 reaches the command position by repeating the above procedure (step 107 YES), the pulse voltage applied between the electrode 32 and the workpiece w is made zero. (Step 115). Then, if the command position is the final command position (step 1
16 YES), the machining is completed, and the workpiece w has a vertical hole w
r is processed.

Further, in order to form the curved hole wr from the commanded position, the pulse voltage is made zero (step 11).
5) The tilt control board 50 drives the first servo motor 26 and the second servo motor 27 to tilt the workpiece w in a predetermined direction (step 117 in FIG. 3).
(D)). As a result, the electrode 32 comes into contact with the processed surface of the workpiece w. Next, after the pulse voltage is applied again (step 101), as described above, the electrode 32 is sucked by the tip end surface of the tube 34 and moved up to the upper limit lock position, and then the jetting amount and the sucking amount of the working fluid are changed. By controlling the distance between the electrode 32 and the machined surface of the workpiece w, the electric discharge machining is performed (steps 102 to 1).
08, steps 109 to 114 (see FIG. 3E). Then, as the electric discharge machining progresses, the electrode 32 reaches the lower limit position of the dimension d from the tip surface of the tube 34,
When the distance between the electrode 32 and the machined surface of the workpiece w becomes wider, the discharge automatically stops (see FIG. 3 (F)). When it is determined in step 114 that no current flows between the electrode 32 and the workpiece w, steps 102 to 1 are performed again.
When the processes up to 07 are executed and the center of the tip of the electrode 32 is not at the commanded position (step 107 NO), the tube 34 is fed by a certain amount by the feed roller 36r (step 108, see FIG. 3 (A)). As a result, the electrode 32 comes into contact with the processed surface of the workpiece w.

Such a procedure is repeatedly executed to perform electric discharge machining, and the center of the tip of the electrode 32 is moved to the next command position P.
_{When n + 1} is reached (step 107 YES), the pulse voltage is set to zero (step 115), and then the tilt control board 50 is reached.
The first servo motor 26 and the second servo motor 27
Is driven and the workpiece w is inclined in a predetermined direction. In this way, the commanded position is calculated as shown in FIG.
As shown in (C), P _{n + 1} , ..., P _{n + n} are designated, and the workpiece w is tilted in a predetermined direction each time the tip center of the electrode 32 reaches the command position. By doing so, it becomes possible to form a curved hole wr having a radius R in the workpiece w. In addition, the command position is shown in FIG.
As shown in (A), by designating P _{n + 1} , ..., P _{n + n} , it becomes possible to form a polygonal bent hole wr.

Here, the electrode 3 for the tube 34
Assuming that the maximum inclination angle of 2 is αmax, as shown in FIG. 2A, the electrode 32 can be inclined until its upper surface comes into contact with the distal end surface of the tube 34, so αmax = 90 ° -COS
It is represented by ^-1 (d / r1). Note that d is the maximum distance between the tip surface of the tube 34 and the upper surface of the electrode 32, and r1 is the radius of the tip surface of the tube 34. Therefore, the workpiece w
By making the inclination of α max or less, interference between the tube 34 and the electrode 32 can be prevented. Also, FIG.
The radius R of the curved hole wr shown in (B) is R = ΔL ÷
It is represented by (2SIN (α / 2)). Here, ΔL is the distance between the command positions, that is, the length of the minute line segment, and α is the angle formed by the minute line segment. By making ΔL and α constant, it is possible to process a curved hole having a constant curvature.

FIG. 6 shows that the bending hole wr bulges outward when bending. This is because the bending hole is machined vertically and then the electrode 32 is machined by rotating the electrode 32 around the universal joint U fixed to the tip of the tube 34. When the radius of the tip sphere of the electrode 32 is r2, the rotation angle of the electrode 32 is α, and the distance from the universal joint U to the center C of the tip sphere is h, the bulge amount e is e = r2- (r2-hSIN α ) = HSIN α Therefore, the bulge amount e increases in proportion to the distance h and the rotation angle α. Therefore, when the allowable value of the bulge amount e is E, the maximum value of the rotation angle αmax2 is αmax2 = SIN ^-1 (E / h)
It is represented by Therefore, by setting the rotation angle of the electrode 32 to be less than or equal to αmax2, it becomes possible to process the curved hole Wr while suppressing the bulge amount e within the allowable value.

As described above, according to the curved hole machining method by electric discharge machining according to the present embodiment, since the electrode 32 is always advanced in the direction of gravity to incline the workpiece w, the electrode 32 is three-dimensionally formed. Since a joint mechanism for moving the curved hole wr is not necessary, it is possible to reduce the size of the portion forming the bending hole wr. Therefore, it becomes possible to form the bent hole wr having a small diameter. Further, since the electrode 32 always advances in the direction of gravity, the tip position and direction of the electrode 32 can be accurately grasped, and the processing accuracy of the bent hole wr is improved.

Although the embodiments of the present invention have been described above, the embodiments of the present invention have various technical matters as described below in addition to the technical matters described in the claims. Please note that. (1) In the curved hole machining apparatus by electric discharge machining according to claim 2, a ring having an outer diameter substantially equal to the inner diameter of the curved hole to be machined is attached to the outer peripheral surface of the tube. Curved hole drilling equipment by electric discharge machining. Therefore, when the electrode is consumed by the electric discharge and the inner diameter of the bent hole becomes small, the tube cannot enter the bent hole, and the electric discharge machining is automatically stopped. (2) In the curved hole machining apparatus by electric discharge machining as set forth in claim 3, the interval adjusting means includes an interval between the electrode and the machined surface of the workpiece such that the no-load voltage application time is substantially equal to the reference time. A curved hole drilling device by electrical discharge machining, which is characterized by adjusting the. Therefore, the electric discharge machining is favorably performed.

[0029]

According to the present invention, since the portion forming the curved hole can be downsized, it is possible to process the curved hole having a small diameter. Further, since the electrode always advances in the direction of gravity, it is possible to accurately grasp the tip position of the electrode and the like, thereby improving the machining accuracy of the bent hole.

[Brief description of drawings]

FIG. 1 is an overall schematic view of a curved hole machining apparatus by electric discharge machining according to an embodiment of the present invention.

FIG. 2 is a detailed view of section II in FIG.

FIG. 3 is a side view showing a curved hole machining method by electric discharge machining according to an embodiment of the present invention.

FIG. 4 is a flowchart showing a curved hole machining method by electric discharge machining according to an embodiment of the present invention.

FIG. 5 is a drawing showing a shape of a center line of a curved hole to be processed.

FIG. 6 is a view showing an outward bulge of a bent hole.

FIG. 7 is a perspective view of a joint mechanism of a conventional bent hole machining apparatus by electric discharge machining and an overall schematic view of the apparatus.

[Explanation of symbols]

 w Workpiece wr Bent hole 14 Main control panel (spacing adjusting means) 20 Tilt adjusting device (tilting adjusting means) 32 Electrode 34 Tube 36 Tube feeding mechanism (tube feeding means) 38a Supply pipe (spacing adjusting means) 38b Recovery pipe ( Interval adjusting means) 38e First adjusting mechanism (space adjusting means) 38f Second adjusting mechanism (space adjusting means)

Claims (3)

[Claims] 1. A method for machining a bent hole in a workpiece by using an electric discharge between the electrode and the workpiece, wherein the electrode is swingable at a tip of a tube bent along the bent hole. It is hung, the workpiece is inclined in a predetermined direction, the tube is fed to advance the electrode in the direction of gravity, and the gap adjusting means makes the gap between the electrode and the machining surface into a dischargeable gap. Curved hole drilling method by electrical discharge machining characterized by adjustment. 2. An apparatus for machining a curved hole in a workpiece by using an electric discharge between an electrode and the workpiece, wherein a tube is bent along the curved hole, and the tube is fed into the curved hole. Tube feeding means, an electrode oscillatingly suspended at the tip of the tube, inclination adjusting means for adjusting the inclination of the workpiece, and a gap between the electrode and the processing surface of the workpiece can be discharged. A curved hole machining device by electric discharge machining, comprising: a space adjusting means for adjusting the space. 3. The curved hole machining apparatus by electric discharge machining according to claim 2, wherein the interval adjusting means is the amount of the machining fluid ejected from the ejection port formed at the tip position of the tube and the tip of the tube. Discharge characterized by adjusting the distance between the electrode and the processing surface of the workpiece by adjusting the amount of the processing liquid sucked from the suction port formed facing the back surface of the electrode at the position. Bending hole processing device by processing.