JP2008302459A - Electric discharge machining device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To form a linear lateral hole by electric discharge machining, and to eliminate a discharge defect of sludge and cooling insufficiency of an electrode. <P>SOLUTION: The electrode 2 and a supporting body 4 are connected by a coil spring 3. In a guide member 5 inserted into a hole 11 of a workpiece 1, an electrode guide hole 53 for guiding advancing directions of electrode assemblies 2-4 is formed. The electrode guide hole 53 is bent after extended in parallel to the hole 11. The coil spring 3 is bent at a bent portion of the electrode guide hole 53, a portion slipped out from the guide hole 53 of the coil spring 3 is restored into a linear shape, a distal end of the coil spring 3 is moved straight in a direction bent at the bent portion, and the linear lateral hole 13 is formed. Machining liquid is supplied to a machining part via the inside of the electrode assemblies 2-4. Cross sectional shapes of the electrode assemblies 2-4 are made different from a cross sectional shape of the electrode guide hole 53 to form a passage between them. The machining liquid and sludge are discharged to the outside of the guide member 5 from the machining part via the passage. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an electric discharge machining apparatus that forms a horizontal hole with respect to a first hole.

The conventional electric discharge machining apparatus stores a coil spring in which an electrode is attached at one end and a bending shape having a predetermined curvature is given by a bending member in a guide pipe, and the coil spring is directed to the workpiece with respect to the guide pipe. When the coil spring is sent to the arc, the part of the coil spring that has come out of the guide pipe has an arc shape with a predetermined curvature, and the electrode advances in an arc shape to form a bent hole in the workpiece (for example, a patent) Reference 1).
JP 2001-205523 A

  By the way, in the injector body of the injector for diesel engines, a storage hole for storing the piezoelectric actuator and a return hole for returning low-pressure fuel to the fuel tank side are formed in parallel. In addition, in order to return the fuel leaking into the storage hole to the fuel tank side, it has been studied to connect the storage hole and the return hole with a small-diameter horizontal hole. This horizontal hole extends from the storage hole toward the fuel return hole. It is desirable that the hole extends linearly.

  However, in the above-mentioned conventional apparatus, it becomes a bent hole and cannot form a lateral hole extending linearly.

  Moreover, since it is a curved hole, it cannot be used by rotating the electrode. If the electrode does not rotate, the hole cannot be machined if a hole is made in the tip of the electrode. Therefore, the machining fluid supply hole cannot be made in the tip of the electrode, and the machining liquid cannot be supplied. For this reason, there is a problem that waste (sludge) generated during processing is poorly discharged and the electrode is insufficiently cooled, so that only extremely slow processing can be performed.

  In view of the above points, the main object of the present invention is to enable linear transverse holes to be formed by electric discharge machining. Another object is to eliminate sludge discharge failure and insufficient cooling of the electrodes.

  In the first feature of the present invention, the work piece (1) in which the linear first hole (11) is formed and the electrode (2) in which the supply hole (22) through which the working fluid is circulated are formed. The electric discharge machining apparatus that forms a linear horizontal hole (13) that communicates with the first hole (11) and is not parallel to the first hole (11) by rotating the electrode (2). The electrode (2) is attached to one end side, and the coil spring (3) for flowing the working fluid toward the supply hole (22) is coupled to the other end side of the coil spring (3). And a cylindrical support (4) for flowing the machining fluid toward the coil spring (3), and a guide member (5) inserted and fixed in the first hole (11). The guide member (5) Is bent after extending in parallel with the first hole (11) and supporting the electrode (2) and the coil spring (3). An electrode guide hole (53) for guiding the traveling direction of the body (4) is formed, and the shape of the cross section orthogonal to the traveling direction of the electrode (2), the coil spring (3) and the support (4), and the electrode The shape of the cross section perpendicular to the traveling direction in the guide hole (53) is different.

  In such a configuration, the coil spring (3) is bent in a direction non-parallel to the first hole (11) at the bent portion of the electrode guide hole (53), and from the guide hole of the coil spring (3). The part that has come out is restored to a straight line, and the tip of the coil spring (3) goes straight in the direction bent at the bent part. Therefore, the electrode (2) attached to the tip of the coil spring (3) also advances linearly, and a straight horizontal hole (13) can be formed by electric discharge machining.

  Moreover, since the straight horizontal hole (13) is formed, the electrode (2) can be rotated and used, and a machining liquid supply hole is provided at the tip of the electrode (2) to supply the machining liquid. can do. Further, since the cross-sectional shape of the electrode (2) and the like and the cross-sectional shape of the electrode guide hole (53) are different, a passage is formed between the electrode (2) and the electrode guide hole (53), and the passage is formed through the passage. Then, the machining fluid and the sludge can be discharged from the processing portion to the outside of the guide member (5). Therefore, sludge discharge failure and insufficient cooling of the electrode (2) can be solved, and the processing speed of the lateral hole (13) can be increased.

  According to the second feature of the present invention, there is a gap between the workpiece (1) in which the linear first hole (11) is formed and the electrode (2) in which the supply hole (22) through which the machining liquid is circulated is formed. The electric discharge machining apparatus that forms a linear horizontal hole (13) that communicates with the first hole (11) and is not parallel to the first hole (11) by rotating the electrode (2). The electrode (2) is attached to one end side, and the coil spring (3) for flowing the working fluid toward the supply hole (22) is coupled to the other end side of the coil spring (3). And a cylindrical support (4) for flowing the machining fluid toward the coil spring (3), and a guide member (5) inserted and fixed in the first hole (11). The guide member (5) Is bent after extending in parallel with the first hole (11) and supporting the electrode (2) and the coil spring (3). The electrode guide hole (53) for guiding the traveling direction of the body (4) and the discharge passage (56) for discharging the machining liquid supplied to the electric discharge machining portion to the outside of the guide member (5) are formed separately. Has been.

  In such a configuration, a linear lateral hole (13) can be formed by electric discharge machining, as in the first feature of the present invention.

  Moreover, while being able to supply a process liquid to a process part, a process liquid and sludge can be discharged | emitted out of a guide member (5) from a process part via a discharge channel (56). Therefore, sludge discharge failure and insufficient cooling of the electrode (2) can be solved, and the processing speed of the lateral hole (13) can be increased.

  In addition, the code | symbol in the bracket | parenthesis of each means described in a claim and this column shows the correspondence with the specific means as described in embodiment mentioned later.

(First embodiment)
A first embodiment of the present invention will be described. FIG. 1 is a partial cross-sectional view of the electric discharge machining apparatus according to the first embodiment, and FIG. 2 is an enlarged cross-sectional view of a main part of FIG.

  As shown in FIGS. 1 and 2, the injector body 1 of the injector for a diesel engine as a workpiece has a cylindrical storage hole 11 in which a piezo actuator (not shown) is stored, and low-pressure fuel as fuel. A cylindrical return hole 12 for returning to the tank (not shown) side is formed in parallel by cutting. Moreover, the horizontal hole 13 which connects the storage hole 11 and the return hole 12 is formed by electrical discharge machining. In order to form this horizontal hole 13, the electrode 2, the coil spring 3, the support body 4, the guide member 5, etc. are used.

  3 is a view showing a state in which the electrode 2, the coil spring 3 and the support 4 are integrated, FIG. 4 is an exploded perspective view of the electrode 2 and the joint 6, and FIG. 5 is an enlarged sectional view of the coil spring 3 in a bent state. is there.

  As shown in FIGS. 3 and 4, the electrode 2 is formed in a substantially hemispherical cup shape with a conductive material such as a copper alloy, and an internal thread 21 is formed on the inner peripheral portion on the opening end side, On the bottom side, a plurality of supply holes 22 for circulating the processing liquid are formed. The coil spring 3 is a tightly wound cylindrical coil spring formed of a piano wire.

  The electrode 2 and the coil spring 3 are connected by a joint 6. The joint 6 is caulked after the lead wire 7 and the wire 8 are inserted into a pipe made of a conductive material such as a copper alloy. The shape after caulking of the joint 6 is a Y-shape having three pieces 61 when viewed along the axial direction. The groove 62 formed between the two adjacent pieces 61 functions as a passage through which the machining fluid flows. A male screw 63 is formed on the top of each piece 61. The male screw 63 and the female screw 21 of the electrode 2 are screwed together, and the joint 6 is inserted into the coil spring 3, whereby the electrode 2 and the coil spring 3 are coupled. ing.

  The support 4 is formed in a cylindrical shape with a conductive material such as a copper alloy, and one end thereof is inserted into the coil spring 3 and coupled to the coil spring 3. Then, the machining fluid is supplied to the electric discharge machining section through the inside of the support 4, the inside of the coil spring 3, the groove 62 of the joint 6, and the supply hole 22 of the electrode 2.

  The lead wire 7 and the wire 8, one end of which is caulked to the joint 6, pass through the inside of the coil spring 3 and the inside of the support body 4 and protrude from the end of the support body 4. The lead wire 7 is connected to a power supply device for electric discharge machining (not shown), and electric power for electric discharge machining is supplied from the power supply device to the electrode 2 via the lead wire 7 and the joint 6. The wire 8 is composed of a piano wire and is coupled to a spring (not shown) and is given tension by the spring. In other words, the electrode 2 and the coil spring 3 are attracted toward the support 4 by the spring.

  As shown in FIG. 5, a retractable cylindrical cover 31 is disposed in close contact with the outer periphery of the coil spring 3, so that the inner peripheral space and the outer peripheral space of the coil spring 3 are separated by this cover 31. Airtightly separated.

  This cover 31 is formed by resin coating. Specifically, a liquid coating material is sprayed on the outer peripheral surface of the coil spring 3 in the close contact state, and then the coating material is dried to form the cover 31. In addition, as a coating material, the coating material (For example, CMT-101 by Yoshida SKT Co., Ltd.) which has silicon as a main component can be used.

  Here, what moves integrally with the electrode 2, that is, the electrode 2, the coil spring 3, and the support body 4 are hereinafter referred to as electrode assemblies 2 to 4. The electrode assemblies 2 to 4 are driven to reciprocate and rotate by driving means (not shown).

  6 is a cross-sectional view taken along the line AA in FIG. 1, and FIG. 7 is an exploded perspective view of the guide member 5.

  As shown in FIGS. 1, 2, 6, and 7, the guide member 5 is made of an insulating material such as resin, and has a cylindrical tubular guide portion 51 that is inserted into the storage hole 11 of the injector body 1. It is provided with a flat plate-like guide portion 52 that is positioned on one end side of the tubular guide portion 51 and positioned in contact with the end face of the injector body 1.

  The cylindrical guide portion 51 and the plate-like guide portion 52 are formed with electrode guide holes 53 through which the electrode assemblies 2 to 4 enter and guide the traveling direction of the electrode assemblies 2 to 4. The electrode guide hole 53 extends from the end face of the plate-like guide portion 52 toward the other end side of the cylindrical guide portion 51 in substantially parallel to the storage hole 11 of the injector body 1, and then the other end of the cylindrical guide portion 51. It bends 90 ° near the side and opens on the outer peripheral side surface near the other end of the cylindrical guide portion 51.

  Further, the electrode guide hole 53 has a square cross-sectional shape orthogonal to the traveling direction of the electrode assemblies 2 to 4. The outer shape of the cross section orthogonal to the traveling direction of the electrode assemblies 2 to 4 is circular. In other words, the shape of the cross section orthogonal to the traveling direction of the electrode assemblies 2 to 4 in the electrode guide hole 53 is different from the outer shape of the cross section orthogonal to the traveling direction of the electrode assemblies 2 to 4. Yes.

  Due to the difference in shape between the electrode guide holes 53 and the electrode assemblies 2 to 4, four passages 9 are formed between the electrode assemblies 2 to 4 and the electrode guide holes 53. The passage 9 functions as a machining fluid return passage.

  As shown in FIG. 7, the guide member 5 is configured by connecting two divided bodies 5 </ b> A and 5 </ b> B divided around the electrode guide hole 53 with bolts (not shown). As described above, the electrode guide hole 53 can be easily processed by dividing the electrode guide hole 53 around the center. A bolt through hole 54 is formed in one of the divided guide members 5A, and a female screw 55 into which the bolt is screwed is formed in the other guide member 5B.

  Next, processing of the horizontal hole 13 of the injector body 1 will be described. In addition, before processing the horizontal hole 13, the storage hole 11 and the return hole 12 of the injector body 1 are formed by cutting.

  First, the electrode assemblies 2 to 4 are inserted into the electrode guide holes 53 of the guide member 5, and the electrode assemblies 2 to 4 are advanced until the electrode 2 reaches the opening end of the electrode guide holes 53. In this state, the intermediate portion of the coil spring 3 is bent 90 ° at the bent portion of the electrode guide hole 53.

  Subsequently, as shown in FIG. 1, the cylindrical guide portion 51 of the guide member 5 is inserted into the storage hole 11 until the plate-like guide portion 52 of the guide member 5 comes into contact with the end surface of the injector body 1.

  Subsequently, supply of the machining fluid to the electric discharge machining unit is started, and the electrode assemblies 2 to 4 are advanced while being rotated, and are discharged between the injector body 1 and the electrode 2. Thereby, the horizontal hole 13 is formed.

  Here, the coil spring 3 is bent in a direction substantially perpendicular to the storage hole 11 at the bent portion of the electrode guide hole 53, and the portion of the coil spring 3 that has come out of the guide hole 53 is restored to a straight line, The distal end side (electrode 2 side) of the coil spring 3 goes straight in the direction bent at the bent portion. Therefore, the electrode 2 attached to the tip of the coil spring 3 also advances linearly in a direction substantially perpendicular to the accommodation hole 11 and is substantially perpendicular to the accommodation hole 11 (that is, non-parallel to the accommodation hole 11). A straight horizontal hole 13 is formed.

  Further, since the coil spring 3 is tightly wound, the portion of the coil spring 3 that has come out of the guide hole 53 is easily restored and maintained in the linear shape, and the linear lateral hole 13 can be reliably formed. .

  In addition, since the electrode 2 and the coil spring 3 are attracted to the support 4 side by the spring coupled to the wire 8, the adjacent coil is surely in close contact with the portion of the coil spring 3 that has come out of the guide hole 53. Thus, the linear shape is more reliably restored and maintained.

  Further, since the machining fluid is supplied to the electric discharge machining portion through the inside of the support 4, the inside of the coil spring 3, the groove 62 of the joint 6, and the supply hole 22 of the electrode 2, there is insufficient cooling of the electrode 2. It will be resolved. Further, sludge generated during processing is discharged out of the guide member 5 through the passage 9 together with the processing liquid. Therefore, sludge discharge failure and insufficient cooling of the electrode 2 can be resolved, and the processing speed of the lateral hole 13 can be increased.

  Further, when the cover 31 is not provided, the processing liquid leaks from between the coils to the outer peripheral space of the coil spring 3 at the bent portion of the coil spring 3, but the leakage is prevented by the cover 31. It is possible to reliably supply the machining fluid.

  Further, since the electrode assemblies 2 to 4 are rotated, the surface roughness and roundness of the horizontal hole 13 can be reduced.

(Second Embodiment)
A second embodiment of the present invention will be described. 8 is a cross-sectional view of the main part in the electric discharge machining apparatus according to the second embodiment, FIG. 9 is a cross-sectional view taken along line BB in FIG. 8, and FIG. It is a perspective view.

  In the present embodiment, the shape of the electrode guide hole 53 in the first embodiment is changed. In addition, the same code | symbol is attached | subjected to the same or equivalent part as 1st Embodiment, and the description is abbreviate | omitted.

  As shown in FIGS. 8 to 10, the electrode guide hole 53 of the present embodiment has a shape of a cross section orthogonal to the traveling direction of the electrode assemblies 2 to 4 and a part of two circles having different diameters. It has a shape. In other words, the shape of the cross section orthogonal to the traveling direction of the electrode assemblies 2 to 4 in the electrode guide hole 53 is different from the outer shape of the cross section orthogonal to the traveling direction of the electrode assemblies 2 to 4. Yes.

  Specifically, the electrode guide hole 53 has an electrode guide part 53a that guides the traveling direction of the electrode assemblies 2 to 4 through which the electrode assemblies 2 to 4 enter, and a smaller diameter than the electrode guide part 53a. It consists of an escape portion 53b that functions as a liquid return passage.

  Then, the machining fluid is supplied to the electric discharge machining section through the inside of the support body 4, the inside of the coil spring 3, the groove 62 of the joint 6 (see FIG. 4), and the supply hole 22 of the electrode 2. Further, sludge generated during processing is discharged out of the guide member 5 together with the processing liquid through the escape portion 53b.

(Third embodiment)
A third embodiment of the present invention will be described. FIG. 11 is a cross-sectional view of a main part in the electric discharge machining apparatus according to the third embodiment, and FIG. 12 is a cross-sectional view taken along the line CC of FIG.

  In the present embodiment, a passage for discharging sludge out of the guide member 5 is provided separately from the electrode guide hole 53. In addition, the same code | symbol is attached | subjected to the same or equivalent part as 1st Embodiment, and the description is abbreviate | omitted.

  As shown in FIGS. 11 and 12, the electrode guide hole 53 has a circular cross-sectional shape orthogonal to the traveling direction of the electrode assemblies 2 to 4. In other words, the shape of the cross section orthogonal to the traveling direction of the electrode assemblies 2 to 4 in the electrode guide hole 53 is similar to the outer shape of the cross section orthogonal to the traveling direction of the electrode assemblies 2 to 4. is there.

  A discharge passage 56 that extends from the end face of the plate-like guide portion 52 (see FIG. 7) toward the other end side of the tubular guide portion 51 substantially parallel to the storage hole 11 of the injector body 1 is provided on the outer periphery of the guide member 5. Is formed. The discharge passage 56 communicates with the opening on the cylindrical guide portion 51 side in the electrode guide hole 53.

  The discharge passage wall surface 57 facing the discharge passage 56 in the outer peripheral surface of the cylindrical guide portion 51 is directed toward the axis of the cylindrical guide portion 51 when viewed along the axial direction of the storage hole 11 of the injector body 1. It is in the shape of a convex arc. If the shape of the discharge passage wall surface 57 is set in this way, the area of the discharge passage 56 is increased while ensuring the contact area between the surface of the injector body 1 that forms the storage hole 11 and the outer peripheral surface of the cylindrical guide portion 51. be able to.

  Then, the machining fluid is supplied to the electric discharge machining section through the inside of the support 4, the inside of the coil spring 3, the groove 62 of the joint 6, and the supply hole 22 of the electrode 2. Further, sludge generated during processing is discharged out of the guide member 5 through the discharge passage 56 together with the processing liquid.

(Other embodiments)
In each of the above embodiments, the wire 8 made of piano wire is used. However, as shown in FIG. 13, the wire 8 is a conductive coating layer formed on the outer periphery of the core wire 81 made of piano wire, for example, by copper plating. 82 may be provided. According to this, electric power for electric discharge machining is supplied to the electrode 2 even through the coat layer 82, and the overall electric resistance can be reduced.

  In each of the above embodiments, electric power for electric discharge machining is supplied from the power supply device to the electrode 2 via the lead wire 7 and the joint 6. However, the lead wire 7 is abolished and electric power for electric discharge machining is supplied from the power supply device to the support body. 4, and may be supplied to the electrode 2 via the coil spring 3 and the joint 6. In this case, as shown in FIG. 14, the coil spring 3 is desirably provided with a conductive coat layer 32 on the outer periphery of a core wire 31 made of a piano wire in order to reduce the electric resistance. Specifically, the coil spring 3 can be manufactured by inserting a piano wire into a copper pipe. In this case, the copper pipe forms the coat layer 32.

  Moreover, in the said 3rd Embodiment, although the discharge channel | path wall surface 57 of the cylindrical guide part 51 was made into the circular arc shape convex toward the axis line of the cylindrical guide part 51, FIG. 15 (CC line of FIG. 11). The discharge passage wall surface 57 of the cylindrical guide portion 51 may be linear as shown in FIG. Alternatively, as shown in FIG. 16 (corresponding to a cross-sectional view taken along the line C-C in FIG. 11), the outer peripheral surface shape of the cylindrical guide portion 51 when viewed along the axial direction of the storage hole 11 of the injector body 1. May be hexagonal.

It is a figure which shows the electric discharge machining apparatus which concerns on 1st Embodiment of this invention in a partial cross section. It is an expanded sectional view of the principal part of FIG. It is a figure which shows the state by which the electrode 2, the coil spring 3, and the support body 4 of 1st Embodiment were integrated. It is an exploded perspective view of electrode 2 and joint 6 of a 1st embodiment. It is an expanded sectional view which shows the bending state of the coil spring 3 of 1st Embodiment. It is sectional drawing which follows the AA line of FIG. It is a disassembled perspective view of the guide member 5 of 1st Embodiment. It is sectional drawing of the principal part in the electric discharge machining apparatus which concerns on 2nd Embodiment of this invention. It is sectional drawing which follows the BB line of FIG. It is a perspective view of the cylindrical guide part 51 in the guide member 5 of 2nd Embodiment. It is sectional drawing of the principal part in the electric discharge machining apparatus which concerns on 3rd Embodiment of this invention. It is sectional drawing which follows the CC line of FIG. 6 is a cross-sectional view showing a modification of the wire 8. FIG. It is sectional drawing which shows the modification of the coil spring. It is sectional drawing which shows the modification of the guide member. It is sectional drawing which shows the other modification of the guide member.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Injector body (workpiece), 2 ... Electrode, 3 ... Coil spring, 4 ... Support body, 5 ... Guide member, 11 ... Storage hole (1st hole), 13 ... Side hole, 22 ... Supply hole, 53 ... Electrode guide hole.

Claims (2)

The work piece (1) in which the linear first hole (11) is formed and the electrode (2) in which the supply hole (22) through which the working fluid flows are formed are discharged, and the electrode (2 ) To form a straight horizontal hole (13) that communicates with the first hole (11) and is not parallel to the first hole (11),
A coil spring (3) having the electrode (2) attached to one end thereof and flowing a working fluid toward the supply hole (22);
A cylindrical support body (4) coupled to the other end side of the coil spring (3) and allowing the machining fluid to flow toward the coil spring (3);
A guide member (5) inserted and fixed in the first hole (11),
The guide member (5) extends in parallel with the first hole (11) and then bends to guide the traveling direction of the electrode (2), the coil spring (3) and the support (4). A guide hole (53) is formed,
The cross section of the electrode (2), the coil spring (3) and the support (4) perpendicular to the direction of travel, and the cross section of the electrode guide hole (53) perpendicular to the direction of travel. An electric discharge machining apparatus characterized by having a different shape. The work piece (1) in which the linear first hole (11) is formed and the electrode (2) in which the supply hole (22) through which the working fluid flows are formed are discharged, and the electrode (2 ) To form a straight horizontal hole (13) that communicates with the first hole (11) and is not parallel to the first hole (11),
A coil spring (3) having the electrode (2) attached to one end thereof and flowing a working fluid toward the supply hole (22);
A cylindrical support body (4) coupled to the other end side of the coil spring (3) and allowing the machining fluid to flow toward the coil spring (3);
A guide member (5) inserted and fixed in the first hole (11),
The guide member (5) extends in parallel with the first hole (11) and then bends to guide the traveling direction of the electrode (2), the coil spring (3) and the support (4). An electric discharge machining characterized in that a guide hole (53) and a discharge passage (56) for discharging the machining fluid supplied to the electric discharge machining portion to the outside of the guide member (5) are formed separately. apparatus.

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