JPH04310323A - Device and method for electric discharge machining for deep hole - Google Patents

Abstract

PURPOSE:To provide an electric discharge machining device for a deep hole and electric discharge machining method thereof capable of executing electric discharge correctly in the specified depth and specified direction even in the case of the diameter of a boring hole being small and deep. CONSTITUTION:A device main body having an electrode operation part 1, an electrode guide cylindrical electrode 2, guide member 3 and deflection preventing means are equipped, an electrode guide fitting part 46 and a pair of tension roller 40, 40 are equipped with on the deflection preventing means. And, the slender cylindrical electrode 2 located between the electrode fitting part 12a of the device main body and tension roller 40 is pulled downward by the resistance force, the deflection of the slender cylindrical electrode 2 is prevented and a deep hole is made pierceable on a work piece H.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric discharge machining apparatus, and more particularly to an electric discharge machining apparatus for drilling a deep hole by electric discharge machining, and an improvement in a method for electric discharge machining of a deep hole.

0002

2. Description of the Related Art Conventionally, electrical discharge machining apparatuses have been proposed that drill fine holes in a workpiece by electrical discharge machining. This device attaches the rear end side of an electrode formed in an elongated cylindrical shape to the device main body, and applies a voltage pulse between the electrode tip and the workpiece, which is arranged with a small gap at the tip side of the electrode. Electric discharge machining is performed by repeatedly generating electric discharge, simultaneously causing machining liquid to flow into the cylinder of the electrode, and sending the electrode toward the tip while rotating the electrode. This makes it possible to drill a pore approximately the diameter of the electrode at a predetermined position on the workpiece.

0003

[Problem to be Solved by the Invention] However, in such a device, if the diameter of the hole to be drilled is made smaller, the electrode diameter will inevitably become smaller, and if the hole is made deeper, the electrode length will be reduced accordingly. must be set at least as deep as the hole. Therefore, if the hole is to be made thin and deep, the electrode must be made thin and long accordingly. As a result, for example, if the length is 300 mm or more, the diameter is 1,
When electric discharge machining is performed using a long and thin electrode with a diameter of 0 mm or less, the electrode tends to be bent due to machining resistance and centrifugal force due to rotation of the electrode itself. In this case, the electrode feed control is performed by the electrode attachment part of the device body in response to voltage pulses from the electrode tip, so even if bending occurs, processing feed will continue as long as the distance between the electrode tip and the workpiece is a predetermined distance. It is not possible to control the deflection while correcting it. As a result, the progress of machining may be interrupted, and the electrode may be damaged. Furthermore, even if the electrode can be machined, there is a problem in that it may not be possible to drill with a predetermined diameter and in a predetermined direction due to the inclination of the electrode. In particular, when the electrode is formed into a cylindrical shape, its wall thickness becomes thinner, and as the electrode diameter becomes smaller, the flow velocity and pressure of the machining fluid flowing through the inner cylinder tend to become stronger, and it is injected at high pressure onto the workpiece. As a result, the resistance that the electrode receives increases, which promotes the above-mentioned bending of the electrode.

The present invention has been proposed in view of the above-mentioned circumstances, and its purpose is to discharge electricity to a predetermined depth and accurately in a predetermined direction even when the diameter of the hole to be drilled is small and deep. An object of the present invention is to provide a deep hole electric discharge machining device and an electric discharge machining method thereof.

[0005]

[Means for Solving the Problems] The present invention solves the above problems by providing a deep hole electrical discharge machining apparatus having the following features. The apparatus main body of the present invention is provided with a deflection preventing means for preventing the elongated rod-shaped electrode from bending between the electrode attachment part of the apparatus main body and the workpiece. This deflection prevention means includes a biasing member that applies a tensile force in the axial direction to the elongated rod-shaped electrode. This biasing member is disposed at an appropriate position between the electrode mounting portion of the apparatus main body and the workpiece.

The present invention also solves the above problems by providing a deep hole electrical discharge machining method having the following features. In the deep hole electric discharge machining method of the present invention, a biasing member that applies a tensile force in the axial direction to the elongated rod-shaped electrode is disposed between the workpiece and the electrode mounting portion of the apparatus main body. This is a method in which the elongated rod-shaped electrode between the electrode attachment part and the biasing member is pulled in the axial direction and fed toward the workpiece.

[0007]

[Function] The deep hole electrical discharge machining apparatus of the present invention is provided with a biasing member between the electrode attachment part of the apparatus main body and the workpiece, which applies a tensile force in the axial direction to the elongated rod-shaped electrode. It is possible to constantly pull the elongated rod-like electrode between the electrode mounting portion and the biasing member in the axial direction, thereby preventing the elongated rod-like electrode from being bent between the electrode attachment portion and the biasing member. Thereby, even when the elongated rod-like electrode is strongly subjected to machining resistance such as machining fluid injection resistance or centrifugal force due to rotation of the electrode itself, the deflection of the elongated rod-like electrode can be minimized.

Further, in the deep hole electric discharge machining method of the present invention, the elongated cylindrical electrode between the electrode attachment part and the biasing member is constantly pulled in the axial direction and fed toward the workpiece. The biasing member allows the elongated bar-shaped electrode to be processed and fed while being prevented from being bent between the electrode mounting portion and the biasing member. As a result, even when the elongated rod-shaped electrode is subjected to strong machining resistance such as injection resistance of machining fluid or centrifugal force due to the rotation of the electrode itself, it is possible to always perform machining while minimizing the deflection of the elongated rod-shaped electrode. Even when the diameter of the hole to be drilled is small and deep, it can be smoothly processed at a predetermined position, with a predetermined diameter, and in a predetermined direction.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be specifically described below with reference to the drawings. FIG. 1 is an enlarged side view of a main part of an electrode operating section in a deep hole electric discharge machining apparatus according to an embodiment of the present invention, and FIG.
is a front view of FIG. 1; FIG. 3 is a schematic diagram showing the entire deep hole electric discharge machining apparatus. The deep-hole electrical discharge machining apparatus of the present invention includes an apparatus main body, an elongated cylindrical electrode 2 attached to the apparatus main body, and a deflection prevention means for preventing the elongated cylindrical electrode 2 from bending. The main body of the device is shown in Figure 3.
As shown in the figure, it has an electrode operating section 1 disposed at the front, a discharge power source 4, a servo circuit 5, and the like. As shown in FIGS. 1 and 2, this electrode operating section 1 includes a flat substrate 11 whose back surface is attached to the apparatus main body, and a spindle head 12 having an electrode attachment section 12a disposed on the front surface of this substrate 11.
and an electrode guide 1 attached below the front surface of the substrate 11.
3.

The spindle head 12 has an elongated cylindrical electrode 2
It is attached and rotated, and there is an elongated cylindrical electrode 2 at the bottom end.
It has an electrode attachment part 12a to which the rear end is attached, and a hose 14 is connected to the upper end so that machining fluid is sent from this hose 14 into the cylinder of the elongated cylindrical electrode 2. This spindle head 12 is
It is connected via a belt or the like to a spindle motor 15 that is fixed to and moves together with the electrode, and the elongated cylindrical electrode 2 is rotated by the rotational force of the spindle motor 15. Further, the left part of the spindle head 12 is connected to a long bar-shaped Z-axis ball screw 16 arranged vertically on the front side of the board 11, as shown in FIGS. It is slidably attached to a guide 17 disposed in the. This Z-axis ball screw 16 is provided with a threaded portion on the outer peripheral surface,
A Z-axis motor 18 is provided at the upper end, and when the Z-axis ball screw 16 rotates, the spindle head 12 is moved to the guide 17.
slide along the vertical direction. Further, the rotation of the Z-axis ball screw 16 is electrically controlled by connecting the Z-axis motor 18 to the servo circuit 5 via the Z-axis ball screw driver 19. In this embodiment, the spindle head 12 is configured to move approximately 800 mm in the vertical direction.

The electrode guide 13 is for guiding the tip of the elongated cylindrical electrode 2 to a predetermined position of the hole-drilled part of the workpiece H. One end is fixed to the lower part of the substrate 11, and the other end has an elongated cylindrical shape. It has an insertion hole 13a through which the electrode 2 is inserted. The elongated cylindrical electrode 2 has its rear end connected to the electrode mounting portion 1 of the spindle head 12.
2a, and the distal end side thereof is passed through the insertion hole 13a of the electrode guide 13 and extends downward.

In this embodiment, the deflection prevention means is disposed above the insertion hole 13a of the electrode guide 13, and is located between the electrode guide mounting portion attached to the electrode guide 13 and the electrode mounting portion 12a and the electrode guide 13. and a biasing member that pulls the elongated rod-shaped electrode in the axial direction. This biasing member consists of a pair of tension rollers 4 as shown in FIG.
It has a tension member 45 having a tension of 0.0, 40, and a tension motor 41 as a rotation source for rotating the tension rollers 40, 40. Tension roller 40, 4
0 are each made of a disc-shaped rubber member having elastic force, and as shown in FIG.
0a is formed. Then, the grooves 40a, 40a are arranged so that they face each other, and in the opposing direction (Y-Y
The electrode guide 13 is disposed above the insertion hole 13a of the electrode guide 13 so as to be urged against each other by spring members 40b, 40b, and the elongated cylindrical electrode 2 is passed between the grooves 40a, 40a. Further, one tension roller 40 is connected to a tension motor 41, and by applying rotational force to the tension roller 40 by the tension motor 41, the elongated cylindrical electrode 2 is pulled downward by a resistive force. Mounting part 12a and electrode guide 1
A tensile force in the axial direction can be applied to the elongated cylindrical electrode 2 between the electrode 2 and the electrode 3. The tensile force by these tension rollers 40, 40 is adjusted depending on the diameter of the elongated cylindrical electrode 2, and is approximately 100 g/cm2 for a large diameter one, for example, about 5 mm, and 500 g/cm2 for one with a large diameter of about 0.5 mm. /cm2 is preferable, but it is not limited to this and can be changed as appropriate. Further, the rotation of the tension rollers 40, 40 that provides the tensile force is achieved by connecting the tension motor 41 to a tension motor driver 42, and then connecting the tension motor driver 42 to the Z-axis ball screw driver 19, as shown in FIG. In addition to being connected to the servo circuit 5 to enable electrical control, automatic adjustment can be made in accordance with the movement of the electrode 2. In this embodiment, the number of rotations of the tension rollers 40, 40 and the descending speed of the spindle head 12 are made to match;
The lifting is done against the rotational force of the tension rollers 40, 40. Note that the rotational adjustment of the tension rollers 40, 40 is not limited to this embodiment.
For example, this can be done by using an air motor as the tension motor 41 and independently adjusting the rotation of the air motor, which can be changed as appropriate. Alternatively, the rotation of the tension rollers 40, 40 may be switched between forward and reverse directions, and when the spindle head 12 is raised, the rotation of the tension rollers 40, 40 may be reversed to match this.

Further, in this embodiment, a guide member 3 is provided at a position approximately in the center between the spindle head 12 and the electrode guide 13. While the above-mentioned deflection prevention means prevents the elongated cylindrical electrode 2 from being bent by pulling it in the axial direction, that is, in the direction of the workpiece H, this guide member 3 Deflection is prevented by forcing the elongated cylindrical electrode 2 to pass through a predetermined position so that it does not escape laterally. This guide member 3 includes a main body mounting part 31 that is slidably attached to a guide 17 of a substrate 11 of the device main body, and an insertion hole that is inserted and guided so as not to hinder the vertical movement of the elongated cylindrical electrode 2. 32a, and a moving means for moving the guide member 3 up and down.

This moving means moves the guide member 3 relative to the spindle head 12 in the same direction, so that the electrode guide part 32 is always at a position approximately in the center between the spindle head 12 and the electrode guide 13. Adjust so that the In this embodiment, an elongated rack member 33 having rack teeth on one side and disposed vertically along the guide 17 of the substrate 11, and one end rotatably attached to the deflection prevention member 3 are used. It includes a rack moving member 34 having a meshing portion at an end that meshes with the rack teeth of the rack member 33, and a guide member motor 35 that rotates the rack moving member 34. The rack moving member 34 is rotated by the guide member motor 35 to move on the rack member 33 in the same direction as the spindle head 12,
This allows the guide member 3 to move up and down with respect to the substrate 11. Then, the amount of movement of the rack moving member 34 is set to be half of the amount of movement of the spindle head 12, so that, for example, when the Z-axis ball screw 16 rotates, the spindle head 12 begins to descend. The guide member 3 is also lowered and is then lowered by half the amount that the spindle head 12 is lowered. As a result,
The guide member 3 is always connected to the spindle head 12 and the electrode guide 1.
It is arranged at a position approximately in the center of 3. Adjustment of the movement of the guide member 3 with respect to the spindle head 12 is performed by adjusting the rotation speed of the rack moving member 34, that is, the rotation speed of the guide member motor 35 that rotates the rack moving member 34, in accordance with the amount of movement of the spindle head 12. This can be done by In this embodiment, as shown in FIG. 3, the guide member motor 35 is provided with a guide member motor driver 35a, and this guide member motor driver 35a is connected to a Z-axis ball screw driver 19 that controls the rotation of the Z-axis ball screw 16. It is connected to the servo circuit 5 and electrically controlled to enable automatic adjustment. Note that this adjustment may be performed by adjusting only the guide member motor 35 alone, and can be changed as appropriate.

By providing this guide member 3 in addition to the above-mentioned deflection prevention means, it is possible to prevent the elongated cylindrical electrode 2 from escaping in the lateral direction, and the deflection of the elongated cylindrical electrode 2 can be more efficiently prevented. can be suppressed to Note that the number of electrode guide portions 32 of the guide member 3 is not limited to one; for example, two or more electrode guide portions 32 may be provided at equal intervals between the spindle head 12 and the electrode guide 13 at all times. It may be possible to arrange it approximately in the center with 13, and it can be changed as appropriate. Further, in this embodiment, the guide member 3 is moved in accordance with the spindle head 12, but the guide member 3 is not limited to this embodiment.
It can be changed as appropriate, such as fixing it to 1. Furthermore,
The means for moving the guide member 3 is not limited to the rack member 33 or the like, and may be modified as appropriate.

The method of drilling holes in the workpiece H using this apparatus will be explained in detail below. First, the elongated cylindrical electrode 2
Set the workpiece H so that the perforated part of the workpiece H is positioned below the tip of the electrode, lower the elongated cylindrical electrode 2, and pour the machining fluid from inside the elongated cylindrical electrode 2. A voltage pulse is applied to the workpiece H while injecting it to discharge it. At this time, the deflection preventing member 3 is lowered by the moving means by a distance that is half the amount of descent of the elongated cylindrical electrode 2, and the electrode guide portion 32 of the deflection preventing member 3 is moved approximately at the center between the spindle head 12 and the electrode guide 13. It is held in position. Therefore,
The central part of the elongated cylindrical electrode 2 is prevented from escaping in the lateral direction by the electrode guide section 32, and as a result, the deflection that occurs in the elongated cylindrical electrode 2 is as follows:
When it is 0 mm, it is substantially the same as that of 300 mm. On the other hand, since the tip of the elongated cylindrical electrode 2 is pulled downward by the pair of tension rollers 40, the deflection is smaller than that of at least 300 mm. Therefore, the hole in the workpiece 40 is formed by the elongated cylindrical electrode 2.
Since it acts without being tilted, it has the diameter of the elongated cylindrical electrode 2 and is open in the direction of movement of the elongated cylindrical electrode 2. This allows the elongated cylindrical electrode 2 to be thin and long, for example, 600 mm long, which was previously difficult to use.
Therefore, even those with an outer diameter of 0.5 mm can be easily used.

In this embodiment, a tensioning member 45 serving as a deflection prevention means is disposed above the electrode guide 13 so that the entire elongated cylindrical electrode 2 between the electrode mounting portion 12a and the electrode guide 13 can be pulled. However, the present invention is not limited to this, and the effect can be brought out as long as it is between the electrode attachment part 12a and the workpiece H, and it can be changed as appropriate. Further, the tension member 45 is not limited to one location, but may be provided at two or more locations, and can be changed as appropriate.

[0018]

Effects of the Invention As described above in the embodiments, the deep hole electric discharge machining apparatus of the present invention is provided with a biasing member between the electrode attachment part of the apparatus main body and the workpiece. constantly biasing the elongated rod-shaped electrode between the and the biasing member in the axial direction;
Deflection in between can be prevented. As a result, even when the elongated rod-like electrode is subjected to strong machining resistance such as injection resistance of machining fluid or centrifugal force due to rotation of the electrode itself, the deflection of the elongated rod-like electrode can be minimized, and the elongated rod-like electrode becomes thin. Moreover, even long ones can be easily used.

In addition, in the deep hole electric discharge machining method of the present invention, since the elongated rod-shaped electrode between the electrode attachment part of the apparatus main body and the workpiece is constantly biased in the axial direction, the biasing The member allows processing to be performed while preventing the elongated rod-shaped electrode from being bent between the electrode mounting portion and the biasing member. As a result, even when the elongated rod-shaped electrode is subjected to strong machining resistance such as injection resistance of machining fluid or centrifugal force due to the rotation of the electrode itself, it is possible to always perform machining while minimizing the deflection of the elongated rod-shaped electrode. Even if the diameter of the hole to be drilled is small and deep, it can be processed accurately and smoothly at a predetermined position, with a predetermined diameter, and in a predetermined direction. As described above, the present invention has been able to provide a useful and practical electric discharge machining device for deep holes and an electric discharge machining method thereof, which can accurately perform electric discharge machining in a predetermined diameter and direction even when the diameter of the hole to be drilled is small and deep. be.

[Brief explanation of the drawing]

FIG. 1 is an enlarged side view of a main part of an electrode operation section.

FIG. 2 is a front view of FIG. 1.

FIG. 3 is a schematic diagram of the entire deep hole electric discharge machining apparatus.

FIG. 4 is an explanatory diagram of a tension member in the deflection prevention means.

[Explanation of symbols]

1 Electrode operating section 2 Elongated cylindrical electrode 3 Guide member 12 Spindle head 12a Electrode mounting section 13 Electrode guide 16 Z-axis ball screw 33 Rack member 35 Guide member motor 40 Tension roller 41 Tension motor 42 Tension motor driver 45
tensile member

Claims (2)

[Claims] Claim 1: A device body having an electrode attachment portion; and an axially movable elongated rod-shaped electrode whose rear end side is attached to the electrode attachment portion of the device body; Electric discharge is generated by applying a voltage pulse between the workpiece and the elongated rod-shaped electrode, which are arranged with a gap, and the electric discharge is repeatedly generated while applying machining feed to the tip of the elongated rod-shaped electrode toward the workpiece. In an electric discharge machining device in which a long and thin rod-like electrode penetrates into a workpiece from the tip side and drills a hole, a deflection prevention means prevents the long and thin rod-like electrode from bending between an electrode attachment part of the device body and the workpiece. The deflection prevention means includes a biasing member that applies a tensile force in the axial direction to the elongated rod-shaped electrode, and the biasing member is arranged between the electrode mounting portion of the device main body and the workpiece. The biasing member is arranged at an appropriate position, and the tensile force of the biasing member prevents the elongated rod-shaped electrode from being bent between the electrode mounting portion of the device body and the biasing member. Electric discharge machining equipment for deep holes. [Claim 2] A voltage pulse is applied between the workpiece and the elongated rod-like electrode, the rear end of which is attached to the electrode attachment part of the device main body, and the elongated rod-like electrode is disposed with a minute gap at the tip side. A method in which a hole is drilled by electric discharge machining by generating an electric discharge and repeatedly generating electric discharge while applying machining feed to the tip of the elongated rod-shaped electrode to the workpiece side, so that the elongated rod-shaped electrode infiltrates the workpiece from the tip side. A biasing member that applies a tensile force in the axial direction to the elongated rod-shaped electrode is disposed between the workpiece and the electrode mounting portion of the device main body, and the biasing member that applies a tensile force in the axial direction A deep hole electrical discharge machining method characterized by feeding a rod-shaped electrode toward the workpiece while pulling it in the axial direction.