JP4371604B2 - Hole drilling method with wire electric discharge machine - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a hole machining method using a wire electric discharge machine capable of electric discharge machining a fine finished circular hole in a slit of a metal workpiece or a minute pilot hole using a wire electric discharge machine.
[0002]
[Prior art]
In order to manufacture special molds, it may be necessary to process a fine circular hole in a fine slit, or a fine pilot hole opened in a sintered metal or the like may be enlarged. If the workpiece is thin or the hole diameter is large, drilling, electrolytic machining, laser drilling, etc. are possible, but if the workpiece is thick, use a wire electric discharge machine to connect the electrode wire. A method of performing electric discharge machining after passing through a slit or a pilot hole to a target position is adopted.
[0003]
In this case, as shown in FIG. 7A, a method of gradually expanding the hole diameter while moving the electrode wire relative to the work so as to draw a circle is common. However, when the slit width or pilot hole size is 0.1 mm, the diameter of the circular hole to be machined is 0.2 to 0.3 mm, and the thickness of the workpiece is 100 mm, the electrode wire is accurately rounded by the program. Despite being moved, the processed hole shape may be distorted as shown in FIGS. In addition, as shown in FIG. 7B, the same problem occurs when the pilot hole having a diameter of about 0.1 mm formed in the sintered metal is enlarged.
[0004]
The reason is considered as follows. That is, when the slit width and the hole diameter are very small, chips generated by the electric discharge machining are not discharged well and accumulate in the hole. When electric discharge machining occurs through the chips, the hole diameter becomes unstable, or when the chip accumulated in the hole and the wire electrode are short-circuited or the potential difference is reduced, the wire electrode is processed. , The electric discharge machining is started again from that position, and the place once machined is machined again, resulting in further enlargement of the hole diameter and instability.
[0005]
Further, when the diameter of the circular hole is 0.2 to 0.3 mm, for example, an electric discharge machining is performed using an ultrafine electrode wire having a diameter of 0.05 mm, and a strong tension cannot be applied to a long electrode wire exceeding 100 mm. Therefore, it becomes easy to bend the central part, and further instability in drilling is increased. As a result, it is considered that the hole shape processed as shown in FIGS. 8 and 9 is distorted so as to swell outward from the perfect circle.
[0006]
[Problems to be solved by the invention]
The present invention solves the above-described conventional problems, and uses a wire electric discharge machine capable of performing electric discharge machining into a perfect circle without distorting the shape even when machining a fine circular hole in a thick workpiece. It was made to provide a drilling method.
[0007]
[Means for Solving the Problems]
The hole machining method by the wire electric discharge machine of the present invention made to solve the above problems is a hole machining method in which a fine circular hole is electric discharge machined by the wire electric discharge machine, and the electrode wire is formed from the center of the circular hole. the by repeating Succoth linear processing is relatively moved by radial equivalent distance in the radial direction over the entire circumference at different angles make circular hole drilling, then, the electrode wire along the inner periphery of the circular hole in the circumferential direction It is characterized by carrying out circular processing for relative movement. When the potential difference between the electrode wire and the workpiece decreases or becomes zero, it is preferable to use a wire electric discharge machine in which a program for stopping and reversing the movement of the electrode wire relative to the workpiece is installed.
[0008]
In this way, in the present invention, since the linear processing for moving the electrode wire in the radial direction from the center of the circular hole is incorporated in the movement program of the electrode wire, the chip wire and the electrode wire are temporarily brought into contact with each other. Even when the potential difference of the workpiece becomes zero or decreases, the electrode wire only escapes inward. For this reason, it can be processed into a beautiful perfect circle by circular processing performed after linear processing.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Preferred embodiments of the present invention are shown below.
FIG. 1 is a perspective view conceptually showing an embodiment of the present invention, wherein 1 is a metal work, 2 is a slit formed in the work 1, and 3 is an electrode wire inserted into the slit 2. . Specific numerical values are not particularly limited, but for example, the thickness of the workpiece 1 is 100 mm, the width of the slit 2 is 0.1 mm, the diameter of the electrode wire 3 is 0.05 mm, and the slit 2 It is assumed that a circular hole having a diameter of 0.2 mm is subjected to electric discharge machining at a position 1 mm from the end face. As is clear from the above numerical values, FIG. 1 is drawn ignoring the dimensional relationship.
[0010]
The electrode wire 3 is fixed to a wire electric discharge machine, and the workpiece 1 is set on a bed (not shown) and moves relative to the electrode wire 3 to perform electric discharge machining. The workpiece 1 is mechanically moved according to a program installed in the wire electric discharge machine. In this way, only the workpiece 1 actually moves, but in this specification, it is expressed that the electrode wire 3 moves relative to the workpiece 1. Note that when the electrode wire 3 comes into contact with the workpiece 1 and the potential difference becomes zero, electric discharge machining cannot be performed, so that the relative movement of the electrode wire 3 is immediately stopped and a program is incorporated so as to return to the opposite direction.
[0011]
In the present invention, after the electrode wire 3 is inserted to the center of the circular hole in the slit 2, as shown in FIGS. 2 and 3, the electrode wire 3 is linearly moved while relatively moving in the radial direction of the circular hole ( A program that performs electrical discharge) machining is used. The moving distance is of course equivalent to the radius, in this case 0.1 mm. Next, the electrode wire 3 returns to the center of the circular hole and repeats the same movement at different angles. In this embodiment, the electrode wire is moved relative to the slit 2 in the radial direction by changing the direction by 15 degrees, such as 15 degrees, 30 degrees, and 45 degrees, but this angle may be set freely. . Further, the electrode wire 3 may be moved in the opposite direction as it is without stopping at the center of the circular hole. In this case, the moving distance is equivalent to the diameter.
[0012]
Thus, in the present invention, since the electrode wire 3 is relatively moved in the radial direction from the center of the circular hole, the electrode wire 3 only returns to the center side of the circular hole even if it comes into contact with chips. As in the case of the conventional circular movement program, the hole machining is not made unstable by reversing along the outside of the circular hole and machining the same place again. Therefore, if this movement is repeated over the entire circumference of 360 degrees, a substantially circular hole can be formed if not complete. Thereafter, if the electric discharge machining is performed while the electrode wire 3 is circularly moved along the circumference of the circular hole, the circumferential unevenness is removed by the electric discharge machining, and the electric discharge machining is performed into a clean perfect circle as shown in FIGS. can do.
[0013]
FIG. 6 is a graph showing the relationship between the electrode wire diameter and the thickness of the workpiece that can be subjected to electric discharge machining with the electrode wire. For example, when the wire diameter is 0, 05 mm, the conventional method has a thickness of 20 mm or more. It was difficult to machine the workpiece. This is because the discharge of chips becomes worse and the influence of bending becomes larger. On the other hand, according to the present invention, by changing the movement of the electrode wire, it is possible to skillfully avoid the adverse effects of chip discharge and electrode wire deflection, so it is accurate even for workpieces with a thickness of 100 mm or more. Electric discharge machining becomes possible.
[0014]
In the above embodiment, the circular hole is machined in the slit 2 formed in the workpiece. However, the present invention is applied to a case where a fine pilot hole with low accuracy provided in advance in the workpiece is expanded to a fine circular hole with high accuracy. Can be applied similarly.
[0015]
【The invention's effect】
As explained above, according to the hole machining method using the wire electric discharge machine of the present invention, the linear machining for moving the electrode wire in the radial direction from the center of the circular hole is repeated at different angles. The electrode wire does not escape to the outside due to contact with the chips. For this reason, if circular machining is performed after that, the electrode wire is relatively moved in the circumferential direction, there is an advantage that a fine circular hole can be discharged into a perfect circle shape on a thick workpiece. In addition, there is an advantage that it can be easily implemented because only the program is changed and no hardware improvement of the wire electric discharge machine is required.
[Brief description of the drawings]
FIG. 1 is a perspective view conceptually showing an embodiment of the present invention.
FIG. 2 is a block diagram showing a program used in the embodiment of the present invention.
FIG. 3 is a plan view showing the movement of the electrode wire in the embodiment of the present invention.
FIG. 4 is a photomicrograph showing a cross section of a circular hole processed according to the present invention.
FIG. 5 is a drawing of FIG.
FIG. 6 is a graph showing the relationship between the electrode wire diameter and the thickness of a work piece that can be subjected to electric discharge machining.
7A and 7B are plan views showing the movement of an electrode wire in a conventional method, in which FIG. 7A shows a case where a hole is machined in a slit, and FIG. 7B shows a case where a pilot hole with poor accuracy is enlarged.
FIG. 8 is a photomicrograph showing a cross section of a circular hole processed by a conventional method.
FIG. 9 is a drawing of FIG.
[Explanation of symbols]
1 work, 2 slits, 3 electrode wires

Claims (2)

This is a hole drilling method in which a minute circular hole is electrodischarge machined by a wire electric discharge machine, and linear machining is carried out over the entire circumference by changing the angle from the center of the circular hole and moving the electrode wire in the radial direction relative to the radius. A hole machining method using a wire electric discharge machine characterized in that circular hole machining is performed, and then circular machining is performed in which the electrode wire is relatively moved along the inner circumference of the circular hole in the circumferential direction.   The hole by the wire electric discharge machine according to claim 1, wherein a wire electric discharge machine incorporating a program for stopping and reversing the relative movement of the electrode wire with respect to the work when the potential difference between the electrode wire and the work decreases or becomes zero Processing method.

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