JP2003136343A - Bending hole processing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a bending hole processing method for forming a bending hole 2 desired to a workpiece 1 such as a molding die and a heat exchanging part in reduced processing time by electric discharge work. SOLUTION: To the workpiece 1 comprising a zinc alloy, discharge work is conducted by an electric discharge part 3a of an electrode 3, while the electric discharge part 3a is advanced along a center axis direction of the bending hole 2 to form the bending hole 2 along its moving track. Since the zinc alloy is used as material for the workpiece 1, a sufficiently large processing gap is obtained around the electrode 3 in electric discharge work, and processing dust or gas does not remain in a work part. The electrode 3 is thus advanced to the depth of the workpiece 1, thereby forming the bending hole 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of processing a curved hole for forming a curved hole inside a workpiece, and more specifically, it is required to have high heat conduction characteristics of a molding die, a heat exchange part and the like. The present invention relates to a method of machining a curved hole in which a curved hole is formed in a workpiece by electric discharge machining.

[0002]

2. Description of the Related Art Molding dies and heat exchange parts are provided with a flow path for a working fluid for heat exchange in order to shorten the heating and cooling cycles and to make the heating and cooling rates uniform. There is. For example, in a molding die, in order to further shorten the time required for one molding, a flow path is formed around a cavity to be molded, and a heating medium is supplied to the flow path before resin filling to make the mold. Is heated, and after the mold is clamped, a cooling medium is supplied to the flow path to cool the mold.

The heat exchange passage is generally formed by drilling since the molding die and the heat exchange parts are formed of metal. However, in drilling, since the drill is rigid, it is not possible to form a curved flow path, and therefore,
The flow path for heat exchange had to be a linear hole.

On the other hand, in the case of an injection molding die, for example, when injection molding or cooling is performed, if there is a temperature difference around the molded product, the molded product may suffer from a defect such as a sink mark which impairs the appearance and strength. It is necessary to heat or cool the periphery of the cavity for molding the molded article at a temperature as uniform as possible, and it is desired to form a heat exchange flow path around the cavity along the contour of the cavity. There is.

Therefore, conventionally, as shown in FIG. 8, a plurality of linear holes 102 are formed around a cavity 101 of a molding die 100 so that some of the linear holes 102 intersect each other and a working fluid is supplied. An unnecessary portion 102a shown by a wavy line in the drawing is closed by leaving an opening for inflow and an outlet, and a flow path is formed around the cavity 101.

[0006]

[Problems to be Solved by the Invention]

However, in the flow path in which a plurality of linear holes 102 are communicated with each other in this way, when the contour of the cavity is a curved surface, the distance between the heat exchange flow path and the cavity is partially different, Further, in the portion where the linear holes 102 intersect, the direction of the flow path changes abruptly, so that the working fluid stays and the entire cavity cannot be heated or cooled at a sufficiently uniform temperature. Met. Therefore, the above-mentioned molding defects such as sink marks cannot be completely prevented.

Further, the heat exchange component also has the same problem, and since the flow path cannot be formed in an arbitrary shape, there is a problem that the heat exchange efficiency is lowered as a whole.

From the above, the present inventor has studied that the curved hole is machined by using electric discharge machining instead of drilling. In this electric discharge machining, a voltage is applied between the electrode and a work such as a molding die or a heat exchange part to generate an electric discharge. Then, by the discharge energy generated by the discharge, while melting or vaporizing the part of the workpiece facing the electrode,
The electrode is introduced into the work piece, and a desired curved hole is to be formed in the work piece along the locus of movement of the electrode.

However, steel materials and aluminum alloys are generally used for molding dies, heat exchange parts, etc., which are required to have high heat conduction characteristics. Since it is not possible to secure a sufficient machining gap between the workpiece and the workpiece, it is impossible to sufficiently discharge the machining chips and gas generated in the machined portion to the outside. Therefore, a short circuit or an abnormal discharge due to these retentions occurred, and holes having a certain depth or more could not be obtained by electrical discharge machining.

On the other hand, a certain depth (for example, 5 mm)
This problem can be solved by pulling out the electrode every time a hole is formed and discharging the processing dust and gas accumulated in the processed part, but the deeper the hole formed by processing becomes , The more it bends, the more the electrode is pulled out,
The process of re-entering the processed portion requires time and labor, and has never been a practically applicable means.

In addition to this, when performing electric discharge machining on a workpiece made of a steel material or an aluminum alloy, not only is the electrode worn out so quickly that it cannot be used at an early stage, but also the work surface of the workpiece is damaged due to the consumption of the electrode. Since the distance fluctuates and the discharge energy fluctuates, it has been impossible to accurately process a bent hole having a desired size and shape.

The present invention has been made in consideration of the above problems, and shortens the machining time for a workpiece such as a molding die or a heat exchange part, and the target curved hole is formed by electric discharge machining. It is an object of the present invention to provide a method for processing a curved hole, which is capable of machining a curved hole and can perform electric discharge machining in a state in which the consumption of the electrode is small.

[0014]

According to a first aspect of the present invention, there is provided a method of machining a curved hole, wherein an electrode having an electric discharge machined portion at least at a tip thereof is used, and a workpiece made of a zinc alloy is subjected to electric discharge machining in the electric discharge machined portion. It is characterized in that the electric discharge machining section is introduced along the center axis of the target curved hole, and the curved hole is formed along the movement trajectory of the electric discharge machining section.

The zinc alloy used as a workpiece has a low work function during electric discharge machining and can form a wider machining gap than steel materials and aluminum alloys. For this reason, it is possible to easily discharge the machining chips and gas generated in the electric discharge machining, to prevent a short circuit or abnormal electric discharge from occurring, improve machining efficiency, and perform stable machining. Therefore, even if the hole is deep or the degree of bending is large, the bent hole can be favorably processed.

Further, since the machining gap is wide and the abnormal discharge is small, the consumption of the electrodes is reduced. Therefore, since the distance between the electrode and the machined surface of the workpiece can be kept constant, a curved hole having a desired shape and size can be accurately formed.

According to a second aspect of the present invention, there is provided a method of machining a curved hole, wherein the workpiece is a molding die, and the electric discharge machining part is introduced along the contour of the cavity around the cavity of the molding die to form the contour of the cavity. It is characterized in that a heating hole or a cooling hole is formed along with.

By advancing the electrode along the contour of the cavity, it is possible to form a curved hole that is equidistant from the cavity over substantially the entire circumference of the cavity. And
By using this bent hole as a heating hole or a cooling hole, it is possible to uniformly heat or cool the entire cavity. Therefore, it is possible to prevent the occurrence of defective molding of the molded product.

According to a third aspect of the present invention, there is provided a method of machining a curved hole, wherein a conductive wire is spirally wound with the same curvature to form an electrode, and a movement locus of an electric discharge machining part in a workpiece matches a spiral electrode shape. As described above, the electrode is inserted in the spiral axis direction while rotating the electrode around the spiral axis with respect to the workpiece to form a spiral bent hole in the workpiece.

Since the locus of movement of the electrode matches the shape of the spiral electrode, the curved hole formed by the locus of movement does not interfere with the electrode to be inserted by electric discharge machining. Therefore, the spiral bent hole can be easily formed in the workpiece without deforming the shape of the entire electrode in accordance with the bent hole during the electric discharge machining.

In the bending hole machining method according to a fourth aspect of the present invention, the electrode is provided with a bendable insulating cylindrical body and a contour which is the same as or thicker than the outer diameter of the insulating cylindrical body, and the posture of which can be controlled at the tip of the insulating cylindrical body. It is characterized in that it is constituted by a supported electric discharge machining unit, and while performing electric discharge machining on a workpiece, the posture of the electric discharge machining unit is controlled so as to face the axial direction of the target curved hole.

By controlling the attitude in the direction of the curved hole in which the electric discharge machining portion is to be formed, the inner surface of the facing workpiece is electric discharge machined, and the curved hole is formed in the movement locus so that the curved surface bends in any direction. Bent holes can be processed.

The insulating cylindrical body for supporting the electric discharge machining section at its tip is
Since it is a bendable insulator, it bends along the machined curved hole, and since it has an outer diameter that is the same as or narrower than the contour of the electric discharge machined part, it can be sufficiently spaced between the inner wall surface of the machined curved hole. Since there is a large gap, it is possible to satisfactorily discharge the processing chips and gas generated in the processed portion.

According to a fifth aspect of the present invention, there is provided a method of machining a curved hole, wherein an electrode formed by spirally winding a conductive wire with the same curvature is used, and a moving locus of an electric discharge machining section in a molding die is a spiral electrode shape. So that the electrode is made to enter the molding die in the spiral axis direction while rotating around the spiral axis to form a spiral cavity in the molding die.

Since the locus of movement of the electrode matches the shape of the spiral electrode, the curved hole formed by the locus of movement does not interfere with the electrode to be inserted by electric discharge machining. Therefore, during the electric discharge machining, the spiral cavity can be easily formed in the workpiece without deforming the shape of the entire electrode according to the bending hole.

By filling the resin into the spiral cavity processed in this way and curing the resin, a spiral molded product is obtained.

[0027]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIGS. 1 to 4 are views for explaining a method of processing a curved hole according to an embodiment of the present invention.
1 shows an electrode holder 4 used in machining, FIG. 2 shows a state in which an electrode 3 used in electric discharge machining is formed, FIG. 3 shows a state in which the electrode 3 is attached to the electrode holder 4, and FIG. The state where the curved hole 2 is machined by electric discharge machining is shown.

In this embodiment, the spiral bending hole 2 is formed in the workpiece 1, and therefore the electrode 3 is formed in a spiral shape. The electrode 3 is made of copper, silver, aluminum, or any other conductive metal material of the same type used in general electric discharge machining. In this embodiment, copper is used. As the base material of the electrode 3, a rod-shaped wire material or a pipe-shaped material is selected.

In order to form the spiral electrode 3 from the rod-shaped wire or pipe-shaped base material, the electrode holder 4 is cut as shown in FIG. The electrode holder 4 has a holder shaft 4a extending in the axial direction, and the electrode holder 4 is attached to the work shaft portion of the lathe.
The cutting blade 5 is moved along the holder shaft 4a while rotating. As a result, the spiral grooves 6 having the same pitch are formed on the outer circumference of the holder shaft 4a.

Next, as shown in FIG. 2, the base material of the electrode is wound around the spiral groove 6 of the holder shaft 4a to form the spiral electrode 3. Since the spiral grooves 6 are formed at the same pitch as described above, the electrode 3 formed by winding around the spiral grooves 6 has a spiral shape with the same curvature in all parts.

After that, the spirally wound electrode 3 is relatively rotated with respect to the electrode holder 4 along the spiral groove 6, and the electrode 3 shown in FIG.
As shown in, the tip portion of the electrode 3 is pulled out from the tip of the holder shaft 4a. As will be described later, the pulled-out tip portion of the electrode 3 enters the workpiece 1 and is accommodated in the formed bending hole 2, so that at least the length of the bending hole 2 to be processed is at least It is pulled out from the tip of the holder shaft 4a so as to be long.

In the state shown in FIG. 3 in which the tip portion of the electrode 3 is pulled out, the base end portion wound around the spiral groove 6 of the electrode 3 is
The holder shaft 4a is fixed by an arbitrary method such as caulking or adhesion.

Then, as shown in FIG.
Is attached to the NC electric discharge machine, the electric discharge machining part 3a at the tip of the electrode 3 is exposed to the workpiece 1, and a voltage on the positive electrode side is applied to the electrode 3 and a voltage on the negative electrode side is applied to the workpiece 1. .

A zinc alloy is used as the material of the workpiece 1. Zinc alloy is suitable as a material for molding dies and heat exchange parts that require short-term heating and cooling cycles because it has high heat conduction characteristics. When used as a steel, the work function of steel is about 4.5 eV, while that of zinc alloy is about 3.4 eV.
The present inventors have found that the material has a low eV and is suitable for electric discharge machining.

The work function is related to the machining gap formed by electric discharge machining. The lower the work function of the cathode material, the more
It has been confirmed that the machining gap is widened in electrical discharge machining under the same conditions, and therefore for zinc alloys,
It is possible to form a wider working gap than steel.

This is because the melting point of zinc alloy is 400 ± 30.
℃, the boiling point is about 900 ℃, because the melting point and boiling point is lower than that of steel material, the depth from the metal surface that melts with one discharge energy is deep, and the evaporation phenomenon also becomes active.
It is considered that the cause is that the molten metal is easily scattered.

In the case of forming the deeply curved hole 2 inside the workpiece 1 as in the present invention, unless the machining waste or gas generated by the electric discharge is discharged to the outside without being accumulated, it is caused by the accumulation. As a result, a short circuit or abnormal discharge is likely to occur and the electric discharge machining cannot proceed. However, since a wide gap is formed between the periphery of the electric discharge machining portion 3a at the tip of the electrode 3 that is performing electric discharge and the workpiece 1, These processing chips and gas can be discharged from the gap through the bent hole 2 already formed. For this reason, machining dust and gas do not locally accumulate, and the electric discharge machining section 3a of the electrode 3 can be inserted deep inside the workpiece 1 to perform electric discharge machining.

Further, since the wide machining gap is formed, the machining speed is increased and the machining efficiency is improved. Furthermore, since the processing gap is wide, the electrode 3 is less likely to be affected by heat due to the discharge energy, and the consumption of the electrode 3 is reduced. As a result, the distance between the electrode 3 and the machined surface of the workpiece 1 can be kept constant, and the intended spirally-shaped curved hole can be formed with high precision.

As the zinc alloy, an alloy having Al: 2 to 20% by weight, Cu: 1 to 20% by weight, Mg: 0.02 to 10% by weight, and a small amount of an effective additive component with the balance being Zn. Can be used. As this alloy, for example, ZAS, ZAPREC (all are trade names of Mitsui Mining & Smelting Co., Ltd.), and other zinc alloys can be selected.

In the electric discharge machining shown in FIG. 4, a positive pole voltage is applied to the electrode 3 and a negative pole voltage is applied to the workpiece 1 to perform electric discharge machining between them, and the center of the curved hole 2 of interest. The tip of the electrode 3 is inserted into the workpiece 1 along the axial direction.

In the present embodiment, since the spiral bent hole 2 having the same shape as the electrode 3 is formed, the movement locus of the tip of the electrode 3 with respect to the workpiece 1 matches the shape of the spiral electrode 3. In addition, the NC electric discharge machine controls the lowering while rotating the electrode holder 4, and advances the electric discharge machining portion 3a at the tip of the electrode 3 in the spiral axis direction while rotating around the spiral axis.

As a result, the electric discharge machining section 3a enters into the workpiece 1 while melting the surface of the workpiece 1 facing it,
Depending on the movement trajectory, the workpiece 1 has a spiral curved hole 2
Is formed.

In the process of inserting the electric discharge machining portion 3a into the workpiece 1 during electric discharge machining, since the shape of the bent hole 2 formed matches the shape of the spiral electrode 3, the electrode that enters by electric discharge machining. 3 does not contact the inner wall surface.
Therefore, the electrode 3 can be smoothly introduced into the workpiece 1 without being deformed in accordance with the shape of the formed bent hole 2 during the electric discharge machining.

If the cylindrical heat exchange part is used as the workpiece 1 and the spirally bent hole 2 is processed along the axis of the cylinder by the processing method according to the present embodiment to form a heat exchange flow path, The entire columnar heat exchange component can be uniformly cooled or heated.

Further, the molding die having the cylindrical cavity is used as the workpiece 1, and the spiral bending hole 2 is formed around the cavity by the processing method according to the present embodiment.
If the flow path for heat exchange is used, the periphery of the cavity can be uniformly heated or cooled, so that defects such as sink marks do not occur in the molded product.

In this embodiment, the electrode 3 is formed by bending a wire rod, and the machining waste or gas generated in the discharge portion is naturally discharged from the gap between the electrode 3 and the workpiece 1 to the outside. Alternatively, the electrode 3 may be formed in a pipe shape to form a flow path for flowing a working liquid or the like in the electrode 3 to flush the discharge portion.

That is, the machining fluid is supplied from the outside into the electrode 3 and supplied to the electric discharge portion, and the machining waste and the gas are forcibly forced to the outside through the bending hole 2 from the gap around the electric discharge machining portion 3a together with the machining fluid. It is also possible that the machining fluid is discharged or, conversely, the machining fluid is caused to flow into the curved hole 2 formed, and the machining chips and gas are sucked together with the machining fluid from the electric discharge machining section 3a and then discharged to the outside through the flow path in the electrode 3.

In this way, by using flushing together with electric discharge machining, it is possible to more reliably discharge machining dust and gas generated in the electric discharge portion to the outside.

A positive electrode voltage may be applied to the entire length of the electrode 3, only the tip facing the workpiece 1 is made of a conductive metal, and the subsequent portion is made of an insulating material. By doing so, the tip portion may be used as the electric discharge machined portion, and a voltage of the positive electrode may be applied to the electric discharge machined portion.

FIG. 5 shows an electrode 9 used for electric discharge machining according to another embodiment of the present invention. Also in this embodiment, a spiral groove 6 having a predetermined pitch is formed on the holder shaft 4a of the electrode holder 4, and a wire rod made of an insulating material is wound around the spiral groove 6 to form a spiral support coil 7
To form. An electric discharge machining portion 8 having a desired shape is attached to the tip of the support coil 7 by welding or the like to form an integrated electrode 9.

The electric discharge machining portion 8 has a block shape or a plate shape having a diameter larger than that of the support coil 7, and forms its contour in accordance with the cross-sectional shape of the bent hole to be formed. Here, in order to machine a curved hole having a star-shaped cross-sectional shape, the electric discharge machining portion 8 has a star-shaped contour as shown in FIG. 5B.

A voltage of positive pole is applied to the electrode 9 and a voltage of negative pole is applied to the workpiece, and as in the embodiment of FIG.
The electrode 9 is inserted into the workpiece while rotating around the spiral axis. As a result, a spiral bent hole having a star-shaped cross section is formed in the workpiece.

When a spiral bending hole is formed by the processing method according to the present embodiment using the molding die as a workpiece, a spiral cavity having the gate opening at the opening of the bending hole can be formed. . When a molten resin is filled into the spiral cavity through the gate port and cured, a spiral molded product having a star-shaped cross section can be molded. The spiral molded product cured in the molding die is taken out from the mold by gripping the end of the molded product exposed at the gate opening with a predetermined jig and pulling it out spirally.

According to the present embodiment, the coil spring, which is conventionally obtained by processing a metal wire by press molding, can be formed by injection molding with a synthetic resin and with a desired cross-sectional shape. Also, by selecting various shapes of the electric discharge machined portion, it becomes possible to form an interesting molded product.

FIG. 6 shows an electrode 10 used in still another embodiment of the present invention. The electrode 10 includes a bendable insulating arm 11 that serves as an insulating cylinder, and a posture controllable at the tip of the insulating arm 11. And an electric discharge machining unit 12 attached to the.

The insulating arm 11 includes a plurality of piece parts 1
It is formed by alternately connecting 3 and 14. The piece parts 13 and 14 are formed of an insulating material in an annular shape.

Further, the piece component 13 is a pair of ears 13 projecting toward the electric discharge machining portion 12 (front side) and having an interval of 180 degrees.
a, 13a and a pair of ears 13b, 13b at 180 degree intervals projecting to the side of the anti-electric discharge machine 12 (rear side), and the piece part 14 has ears 13a of the piece part 13,
It has a pair of ears 14a, 14a connected to 13a and a pair of ears 14b, 14b connected to the ears 13b, 13b of the piece component 13.

To connect the ears of the piece parts 13 and 14, holes are formed in each of the ears, the corresponding ears are superposed so that the holes communicate with each other, and screws 15 are inserted into the communicating holes.
It is performed by inserting. As a result, the adjacent piece parts 13 and 14 can be bent and connected to each other.

The electric discharge machined portion 12 at the tip of the electrode 10 is formed of a conductive metal material in a substantially cylindrical shape, and is loosely fitted from the outside into the concave groove 13c formed on the side surface of the frontmost piece component 13A. It is movably attached to the piece component 13A by the flange 12a.

Further, a coil spring 18 for urging the electric discharge machining portion 12 in the tip direction (forward) is arranged between the foremost piece part 13A and the tip wall 12b of the electric discharge machining portion 12, and an insulating arm is provided. The ends of the four operation wires 16 and 17 which are inserted through the wire 11 at intervals of 90 degrees are the electric discharge machining parts 12.
Is connected to the tip wall 12b of the. With this configuration, by pulling one or more operation wires 16, 17 from the outside of the other end against the elasticity of the coil spring 18, the posture of the electric discharge machining unit 12 can be controlled in any direction.

Further, the central portion of the tip wall 12b of the electric discharge machining portion 12 penetrates in the thickness direction, so that machining chips and gas generated at the time of electric discharge machining, or machining fluid used as necessary, It can be distributed in the annular piece parts 13 and 14.

Also in this embodiment, the workpiece 1 is made of a zinc alloy. Then, a negative pole voltage is applied to the workpiece 1 and a positive pole voltage is applied to the electric discharge machining portion 12 of the electrode 10 to cause electric discharge between the electric discharge machining portion 12 and the workpiece 1. Due to this electric discharge, the machining surface of the workpiece facing the electric discharge machining unit 12 is melted and machining is performed.

FIG. 7 shows a processed state of this embodiment.
At the time of the electric discharge machining, the attitude of the electric discharge machine 12 with respect to the work part 1 is obtained, for example, by taking the difference in the lengths of the four operation wires 16 and 17 drawn out in the distal direction,
Alternatively, the plurality of operation wires 16 and 17 are pulled and operated to control the attitude so as to move toward the desired axial direction of the bent hole 19.

On the other hand, since the insulating arm 11 is bent along the axial direction of the formed bent hole 19, the insulating arm 11 can follow the progress of the electric discharge machining, and the electrode 10 as a whole can smoothly enter the workpiece 1. .

Also in this processing, since the workpiece 1 is made of a zinc alloy and a negative voltage is applied, a wide processing gap can be obtained. Therefore, similarly to the other embodiments, the processing waste and the gas can be smoothly discharged to the outside from the bending hole 19, the processing waste and the gas are not locally retained, and a short circuit or an abnormality due to the retention is caused. Discharge is less likely to occur.

Further, since it is possible to control the direction change of the electric discharge machining section 12 to an arbitrary direction, when the molding die is the work 1, the contour of the cavity is formed around the cavity of the molding die. The electrode 10 can be moved by moving the electrode 10. By this movement, it is possible to form the curved hole 19 having substantially the same length and at equal intervals with the cavity. Therefore, by using this curved hole 19 as a flow path for heat exchange,
The entire cavity can be uniformly heated or cooled, and the occurrence of molding defects such as sink marks can be more reliably prevented.

Further, even if a zinc alloy having a rigidity lower than that of steel is used as the molding die as described above, it can sufficiently withstand the injection molding of the resin.

Although the insulating arm 11 according to the present embodiment is constructed by connecting a plurality of piece parts 13 and 14, it may be integrally constructed by a flexible insulating tube or the like.

The orientation of the electric discharge machining part in the workpiece 1 is determined by the above-mentioned method, and the individual piece parts 13, 1
It is also possible to detect the rotation angle between the four and obtain it from the sum thereof, or to provide a posture detection function in the electric discharge machine itself to control the posture in a target direction.

[0070]

According to the first aspect of the present invention, it is easy to discharge machining chips and gas generated by electric discharge machining, and it is difficult for short-circuiting and abnormal electric discharge to occur. Therefore, curved holes can be efficiently and stably discharged. Can be done in the state.

Further, since the consumption of the electrode is reduced, the distance between the electrode and the machined surface of the workpiece can be kept constant, and the curved hole having the intended shape and size can be machined with high accuracy.

According to the second aspect of the present invention, in addition to the effect of the first aspect of the invention, the entire cavity can be uniformly heated or cooled by the heat exchanging flow path formed of the curved hole. Therefore, it is possible to prevent the occurrence of defective molding of the molded product.

According to the invention of claim 3, claims 1 and 2
In addition to the effect of the present invention, since the spiral electrode is relatively moved while rotating around the spiral axis, the spiral bent hole can be efficiently processed without deforming the shape of the electrode.

According to the invention of claim 4, claims 1 and 2
In addition to the above effect, since the posture of the electric discharge machining portion is controlled in an arbitrary direction, a curved hole bent in an arbitrary direction can be processed, and even a complicated shape can be favorably processed.

According to the fifth aspect of the present invention, an interesting molded product or a coil spring-shaped molded product can be formed by injection molding.

[Brief description of drawings]

FIG. 1 is a side view showing a state in which an electrode holder 4 used in a processing method according to an embodiment of the present invention is prepared.

FIG. 2 is a side view showing a state in which an electrode 3 used for electric discharge machining is formed.

FIG. 3 is a side view showing a state in which an electrode 3 is attached to an electrode holder 4.

FIG. 4 is a front view showing a state in which a curved hole is machined by electric discharge machining.

5A and 5B show an electrode 9 used for electric discharge machining according to another embodiment of the present invention, FIG. 5A is a side view of the electrode 9, and FIG.
FIG. 4 is a front view of the electric discharge machining unit 8.

FIG. 6 is a fragmentary front view showing an electrode 10 used in still another embodiment.

7 is a cross-sectional view showing a state in which a curved hole 19 is processed using the electrode 10 shown in FIG.

FIG. 8 is a plan view showing a conventional processing method for forming a heat exchange passage around a cavity 101 of a molding die 100.

[Explanation of symbols]

1 workpiece 2, 19 curved holes 3, 9, 10 electrodes 3a, 8, 12 EDM part 11 Insulation cylinder (insulation arm)

Continued front page    (72) Inventor Kiyonori Masui             1-2221 Nakanocho, Tomitabayashi City, Osaka Prefecture (72) Inventor Hisashi Minami             1515 Mitsumatsu, Kaizuka City, Osaka Prefecture F-term (reference) 3C059 AA01 AB01 HA09 HA11 HA16                 4E050 JA01 JA02 JB06 JC04 JD03                 4F202 CA11 CD18 CN14

Claims (5)

[Claims] 1. An electric discharge machining part is used while performing electric discharge machining on a workpiece (1) made of a zinc alloy using an electrode (3) having an electric discharge machining part (3a) at least at its tip. (3a) is a curved hole (2)
A method of machining a curved hole, characterized in that the curved hole (2) is formed along the movement axis of the electric discharge machining part (3a) by advancing along the central axis of the curved hole. 2. The workpiece (1) is a molding die, and the electric discharge machined portion (3a) is made to enter along the contour of the cavity around the cavity of the molding die so as to follow the contour of the cavity. The method for processing a curved hole according to claim 1, wherein a heating hole or a cooling hole is formed. 3. An electrode (3) in which a conductive wire is spirally wound with the same curvature to form an electrode (3), and a movement locus of an electric discharge machining part (8) in a workpiece (1) is spiral. In order to match the shape, the electrode (3) is made to enter the workpiece (1) in the spiral axis direction while rotating around the spiral axis, and the spiral bent hole (2) is formed in the workpiece (1). The method for processing a curved hole according to claim 1 or 2, wherein the curved hole is formed. 4. The electrode (10) is positioned at the tip of the insulating tubular body (11) with a bendable insulating tubular body (11) and a contour that is the same as or thicker than the outer diameter of the insulating tubular body (11). It is composed of a controllably supported electric discharge machining part (12), and the electric discharge machining part (1
The posture of 2) is controlled so as to be directed in the axial direction of the target curved hole (19).
The method for processing the described bent hole. 5. The electrode (9) formed by spirally winding a conductive wire with the same curvature, and the movement locus of the electric discharge machined portion (8) in the molding die has a spiral electrode (9) shape. So that the electrode (9) is inserted into the molding die in the spiral axis direction while rotating around the spiral axis to form a spiral cavity in the molding die. The method for processing a curved hole according to claim 1.