JPH04310322A - Device and method for electric discharge machining of deep hole - Google Patents

Abstract

PURPOSE:To provide an electric discharge machining device and electric discharge machining method for a deep hole capable of electric discharge machining correctly 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 13, slender cylindrical electrode 2 and a deflection preventing member 3 are equipped with, on the deflection preventing member 3, a main body fitting part 31, an electrode guide part 32 having an insertion hole 32a which guides the slender cylindrical electrode 2 with its insertion and a rack member 33 moving this deflection preventing member 3 vertically are equipped. And, the deflection preventing member 3 is moved by the half quantity in the same direction relatively to the movement of a spindle head 12 by this rack member 33 to make the electrode guide part 32 comes to the position becoming about the center of the spindle head 12 and electrode guide 13 at all times, 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 feeding control is performed by the electrode mounting part of the device main body in response to the voltage pulse at the electrode tip, so even if bending occurs, the electrode can be fed as long as the distance between the electrode tip and the workpiece is a predetermined distance. cannot be controlled while correcting. 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 includes an electrode guide that is disposed near the upper part of the workpiece and that inserts and guides the elongated rod-shaped electrode into the perforated part of the workpiece, and a Deflection preventing means is provided to prevent the elongated rod-shaped electrode from deflecting. This deflection prevention means includes a main body attachment part that is attached to the apparatus main body, and an electrode guide part that holds and guides the elongated rod-shaped electrode from the side so as not to hinder its movement in the axial direction. The electrode guide section is disposed at an appropriate position between the electrode guide and the electrode mounting section of the main body of the device.

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 electrical discharge machining method of the present invention, an electrode guide for inserting and guiding an elongated bar-shaped electrode into a drilled part of the workpiece is disposed in the apparatus main body near the upper part of the workpiece. An electrode guide part is disposed between the electrode mounting part of the apparatus main body and the electrode guide part that holds and guides the elongated rod-shaped electrode from the side so as not to hinder its movement in the axial direction. This is a method in which the elongated rod-shaped electrode between the electrode attachment part and the workpiece is sequentially held by the electrode guide and the electrode guide part and fed to the workpiece side for processing.

[0007]

[Operation] In the deep hole electric discharge machining apparatus of the present invention, in addition to the electrode guide disposed near the upper part of the workpiece, an elongated rod-shaped electrode is moved in the axial direction between the electrode guide and the electrode mounting part. Since the deflection prevention means has an electrode guide part that is inserted and guided without interfering with the electrode guide part, the electrode guide part prevents the elongated rod-shaped electrode part from escaping in the lateral direction between the electrode guide and the electrode mounting part. This is substantially the same as shortening the elongated rod-shaped electrode. 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 electrical discharge machining method of the present invention, the elongated rod-shaped electrode between the electrode mounting portion and the workpiece is held in sequence by the electrode guide and the electrode guide portion while being machined toward the workpiece. For feeding, the electrode guide guides the tip of the elongated rod-like electrode to the perforated part of the workpiece, while the electrode guide prevents the elongated rod-like electrode from escaping laterally between the electrode mounting part and the electrode guide. can do. 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, processing can be carried out smoothly in a predetermined position, diameter, and 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 front 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.
2 is a side view of FIG. 1. FIG. FIG. 3 is a schematic diagram showing the entire deep hole electric discharge machining apparatus. The deep-hole electric 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 member 3 for preventing the elongated cylindrical electrode 2 from bending. .

As shown in FIG. 3, the main body of the apparatus includes 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 operation section 1 has a flat substrate 1 whose back surface is attached to the main body of the device.
1, and an electrode mounting portion 12a disposed on the front surface of this substrate 11.
The spindle head 12 has a spindle head 12, and an electrode guide 13 attached below the front surface of the substrate 11.

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 the substrate 11 as shown in FIG.
A long bar-shaped Z-axis ball screw 1 arranged vertically on the front side of the
6, and its rear end is slidably attached to a guide 17 arranged vertically on the front surface of the board 11. This Z
The shaft ball screw 16 has a threaded portion on its outer circumferential surface, and is equipped with a Z-axis motor 18 at its upper end, and as the Z-axis ball screw 16 rotates, the spindle head 12 slides along the guide 17 in the vertical direction. In addition, this Z-axis ball screw 16
The rotation of the Z-axis motor 18 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 vertical movement of the spindle head 12 is approximately 80 degrees.
It is designed to be movable by about 0 mm.

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.

The deflection prevention member 3 serves as a deflection prevention means for preventing the elongated cylindrical electrode 2 from deflecting. It is arranged in such a position that This deflection prevention member 3 has 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 through and guides the elongated cylindrical electrode 2 so as not to hinder its vertical movement. It has an electrode guide section 32 having a hole 32a, and a moving means for moving the deflection preventing member 3 up and down.

This moving means moves the deflection preventing member 3 relative to the spindle head 12 in the same direction, so that the electrode guide portion 32 is always at a position approximately at the center between the spindle head 12 and the electrode guide 13. It is adjusted so that it comes to . In this embodiment, a long rack member 33 has rack teeth on one side and is disposed vertically on the guide 17 of the substrate 11, and one end is rotatably attached to the deflection prevention member 3 and the other end is attached to the deflection prevention member 3. A rack moving member 34 having a meshing portion that meshes with the rack teeth of the rack member 33, and a deflection prevention member motor 35 that rotates the rack moving member 34.
It is equipped with The rack moving member 34 is rotated by the deflection prevention member motor 35 to move on the rack member 33 in the opposite direction to the spindle head 12, thereby causing the deflection prevention member 3 to move up and down with respect to the substrate 11. I try to do that. 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. For example, when the Z-axis ball screw 12b rotates, the spindle head 1
2 begins to descend, and accordingly, the deflection prevention member 3 also descends, and is lowered by half the descending amount of the spindle head 12. As a result, the deflection prevention member 3 is constantly connected to the spindle head 12 and the electrode guide 13. It is located approximately in the center of the The movement of the deflection preventing member 3 with respect to the spindle head 12 is adjusted by adjusting the rotation speed of the rack moving member 34, that is, the rotation speed of the deflection preventing member motor 34 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 deflection preventing member motor 34 is provided with a deflection preventing member motor driver 35a, and the deflection preventing member motor driver 35a and the Z-axis ball screw 1
It is connected to and interlocks with a Z-axis ball screw driver 19 that controls the rotation of 6, and is also connected to a servo circuit 5 so that it can be electrically controlled and automatically adjusted. Note that this adjustment may be performed by adjusting only the deflection prevention member motor 34 alone, and can be changed as appropriate.

Furthermore, in this embodiment, the electrode guide 13
The elongated cylindrical electrode 2 is placed above the insertion hole 13a of the workpiece H.
An electrode tensioning means is provided for pulling the electrode in the downward direction (X direction) shown in the figure. This electrode tensioning means is for applying tensile force in the axial direction to the elongated cylindrical electrode 2 by pulling the elongated cylindrical electrode 2 downward, thereby preventing the electrode 2 from being bent. By providing this electrode tensioning means, deflection of the electrode 2 can be more effectively prevented.

This electrode tensioning means includes a tension member 45 having a pair of tension rollers 40, 40, as shown in FIG.
and a tension motor 41 as a rotation source for rotating the tension rollers 40, 40. Each of the tension rollers 40, 40 has a disk shape, as shown in FIG.
As shown in FIG.
a is formed, and the spring 40 is arranged so that the grooves 40a, 40a face each other, and in the opposing direction (Y-Y direction in the figure).
b, 40b are arranged above the insertion hole 13a of the electrode guide 13 so as to urge each other, and the groove 40
The elongated cylindrical electrode 2 is passed between a and 40a. By applying rotational force to one of the tension rollers 40 by the tension motor 41, the elongated cylindrical electrode 2 is pulled downward by a resistive force. The tensile force by these tension rollers 40, 40 is adjusted depending on the diameter of the elongated cylindrical electrode 2, and is 100 g/cm2 if the diameter is large, for example, about 5 mm.
If it is about 0.5mm, 500g/cm2
Although the degree is preferable, it is not limited to this and can be changed as appropriate. Further, the rotation of the tension rollers 40, 40 that provide the tensile force is achieved by connecting the tension motor 41 to a tension motor driver 42 as shown in FIG. It is connected to a Z-axis ball screw driver 19 for interlocking operation, and is also connected to a servo circuit 5 for electrical control so that it can be automatically adjusted 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, while the spindle head 1
2 is raised against the rotational force of the tension rollers 40, 40. Note that the adjustment of the rotation of the tension rollers 40, 40 is not limited to this embodiment; for example, an air motor can be used as the tension motor 41, and the rotation of the air motor can be adjusted independently. It is something that can be changed.

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, as the spindle head 12 descends, the deflection preventing member 3 descends by half the distance, and the deflection preventing member 3
The electrode guide portion 32 is held at a position approximately in the center between the spindle head 12 and the electrode guide 13. Therefore, when the elongated cylindrical electrode 2 has a length of 600 mm, the deflection generated in the elongated cylindrical electrode 2 is substantially the same as when the length of the slender cylindrical electrode 2 is 300 mm. On the other hand, since the tip of the elongated cylindrical electrode 2 is pulled downward by the electrode tensioning means, the deflection is at least smaller than that of 300 mm. Therefore, the hole in the workpiece 40 has the diameter of the elongated cylindrical electrode 2 and is opened in the direction in which the elongated cylindrical electrode 2 moves, since the elongated cylindrical electrode 2 acts without tilting. . This allows the elongated cylindrical electrode 2 to be thin and long, for example, with a length of 600 mm, which was previously difficult to use, and an outer diameter of 0.5 m.
It becomes possible to use it easily and accurately even if it is of m.

Although only one electrode guide portion 32 of the deflection prevention member 3 is provided in this embodiment, the present invention is not limited to this. For example, two electrode guide portions 32 may be provided at equal intervals between the spindle head 12 and the electrode guide 13. Alternatively, three or more may be provided and moved approximately in the center between the spindle head 12 and the electrode guide 13, and this can be changed as appropriate. or,
In the present embodiment, the deflection preventing member 3 is made to fit with the spindle head 12, but it is not limited to this embodiment, and may be modified as appropriate, for example, by fixing it to the substrate 11. Furthermore, the means for moving the deflection prevention member 3 is not limited to the rack member 33 or the like, and may be modified as appropriate.

[0019]

Effects of the Invention As described above in the embodiments, the deep hole electrical discharge machining apparatus of the present invention is provided with a deflection prevention means between the electrode guide and the electrode mounting portion in addition to the electrode guide. The electrode guiding portion can prevent the elongated rod-shaped electrode portion from escaping in the lateral direction between the electrode mounting portion and the electrode mounting portion, and the result can be substantially the same as if the elongated rod-shaped electrode was shortened. This makes it possible to minimize the deflection of the slender cylindrical electrode even when the slender rod-shaped electrode is subjected to strong machining resistance such as injection resistance of machining fluid or centrifugal force due to rotation of the electrode itself. Even if it is thin and long, it can be easily used.

Furthermore, in the deep hole electric discharge machining method of the present invention, the elongated rod-shaped electrode between the electrode mounting portion and the workpiece is held in sequence by the electrode guide and the electrode guide portion while being machined toward the workpiece. For feeding, the electrode guide guides the tip of the elongated bar-shaped electrode to the perforated part of the workpiece, while the electrode guide prevents the elongated bar-shaped electrode from escaping laterally between the electrode mounting part and the electrode guide. Even when the slender 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, processing can be carried out while minimizing the deflection of the slender rod-shaped electrode at all times. Can be done. As a result, even when the diameter of the hole to be drilled is small and deep, the hole in the workpiece can be drilled in a predetermined position, with the diameter of the elongated rod-shaped electrode, and precisely in the direction of movement of the elongated rod-shaped electrode. Become. 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 that 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 drawings]

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 roller.

[Explanation of symbols]

1 Electrode operation section 2　　　　　　　　　　　　Slender cylindrical electrode 3. Deflection prevention member 12 Spindle head 12a　Electrode mounting part 13 Electrode guide 16 Z-axis ball screw 33 Rack components 34 Deflection prevention member motor

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 electrical discharge machining equipment in which a slender rod-shaped electrode penetrates into the workpiece from the tip side to drill a hole, the slender rod-shaped electrode is placed near the top of the workpiece and is guided through the hole in the workpiece. and a deflection preventing means for preventing bending of the elongated rod-shaped electrode between the electrode guide and the electrode mounting section of the device main body, and the deflection preventing means is provided with a main body mounting section that is attached to the device main body. , an electrode guide section that holds and guides the elongated rod-shaped electrode from the side so as not to impede its movement in the axial direction, and this electrode guide section is provided between the electrode guide and the electrode mounting section of the device main body. A deep hole electric discharge machining device characterized in that it is arranged at an appropriate position. [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. In this method, an electrode guide for inserting and guiding an elongated rod-shaped electrode into the perforated part of the workpiece is disposed near the upper part of the workpiece, and an elongated rod-shaped electrode is placed between the electrode guide and the electrode attachment part of the device main body. An electrode guide section that holds and guides the electrode from the side so as not to hinder its movement in the axial direction is provided, and the elongated cylindrical electrode between the electrode mounting section and the workpiece is sequentially moved between the electrode guide and the electrode guide. A deep hole electrical discharge machining method characterized by feeding the workpiece toward the workpiece while holding the workpiece between the parts.