JP5541141B2 - EDM machine - Google Patents

Description

  The present invention relates to an electric discharge machining apparatus suitable for machining fine pores such as nozzle holes and orifices of nozzles for various devices such as a fuel injection device.

  Electric discharge machining is a method of applying a voltage between a metal workpiece, which is a workpiece, and a discharge electrode to generate an electric discharge to melt the workpiece, and is suitable for fine machining (Patent Documents 1 to 5). 3 etc.). FIG. 8A is an example of an electric discharge machining apparatus for drilling described in Patent Documents 1 and 2, and is held by a work 101 placed on a pedestal 102 that is a workpiece and a discharge head 104. Electrodes 103 are arranged opposite to each other, and a machining liquid nozzle 105 is provided between them. FIG. 8B is an example of a wire electrical discharge machining apparatus described in Patent Document 3, and a nozzle 113 that houses a wire guide 112 through which the wire electrode 110 is inserted is close to the upper surface of the workpiece 111. The wire electrode 110 is disposed so as to penetrate the workpiece 111 in the vertical direction. The wire electrode 110 generates electric discharge between the side surfaces of the processing groove 114 and forms a processing groove 114 having a predetermined shape on the workpiece 111 with the horizontal direction as the processing direction.

  In a fuel injection device for a vehicle engine, an electric discharge machining device shown in FIG. 8A is employed as a method for machining micro holes formed in an injection nozzle or an orifice member. The hole forming method by electric discharge machining will be described with reference to FIG. 9A. The electrode 103 of the electric discharge machining apparatus is rotatably supported by the electrode guide 106 and faces the injection nozzle 101 which is a workpiece. The injection nozzle 101 is arranged so that the formation direction of the injection hole 107 coincides with the axial direction of the electrode 103, and a voltage is applied between the two to cause discharge, and a fine injection hole is formed at the tip of the injection nozzle 101. 107 is formed through. At this time, the machining liquid nozzle 105 is disposed on the side of the electrode 103, the machining liquid is supplied from the lateral direction between the electrode guide 106 and the injection nozzle 101, and the sludge is discharged.

JP-T-2006-272484 JP 2008-254117 A JP-A-62-297022

  However, the electric discharge machining apparatus of FIG. 8A requires a sufficient gap between the electrode guide 106 and the injection nozzle 101 in order to supply the machining liquid from the lateral direction of the electrode guide 104. On the other hand, in order to cause discharge, it is necessary to bring the electrode 103 close to the injection nozzle 101, and the length of the electrode 103 protruding downward from the electrode guide 106 becomes longer. Since the electrode 103 for processing the nozzle hole 107 has a fine diameter (for example, about Φ40 to Φ120 μm), it is easily subjected to the pressure of the processing liquid, and as shown in FIG. There has been a problem in that deflection occurs, or vibration of the rotating electrode 103 occurs, resulting in variations in the processing hole diameter.

  With respect to this problem, Patent Document 1 discloses that a work hole is preliminarily formed in a work, and a machining fluid is sucked from the work hole during the fine hole machining, and a vibration means is provided to vibrate the electrode or work in the axial direction. Is disclosed. Thereby, although it is possible to suppress the deflection and deflection of the electrode, a device for laser processing the prepared hole and a suction device for the processing liquid are required. In addition, it takes time for processing and the manufacturing cost increases.

  Patent Document 2 discloses a method for shortening the processing time. Specifically, a predetermined position at which discharge is started between the workpiece and the workpiece is grasped, hole processing is performed with a predetermined feed amount using this as a reference position, and then the electrode is returned by a predetermined return amount. By repeating this, continuous processing is facilitated. Also, during machining, the voltage between the electrode and the workpiece is monitored, the electrode is lowered while it exceeds the predetermined value, and when it falls below the predetermined value, it is controlled to repeatedly discharge, short circuit, and open. Process.

  However, this method is complicated in control and is not practical. This can shorten the time required to set the initial position when performing a plurality of holes, but in a single hole, the electrode repeatedly descends, stops, and rises according to the voltage between the electrodes. As a result, the processing time may be longer.

  On the other hand, the wire electric discharge machining apparatus of FIG. 8B is provided with a nozzle 113 through which the machining fluid flows on the outer periphery of the wire guide 112 that holds the wire electrode 110. In this configuration, since the machining fluid is not supplied from the lateral direction, the gap L1 between the nozzle 113 and the workpiece 111 can be reduced. However, such a device configuration for wire electric discharge machining cannot be simply applied to the drilling device targeted by the present invention, and the following problems arise.

  In this wire electric discharge machining apparatus, the tip of the nozzle 113 has a reduced diameter, the wire guide 112 is accommodated above the reduced diameter portion, and the wire electrode 110 is exposed in the reduced diameter portion. Here, in wire electric discharge machining, as shown in the drawing, since the wire electrode 110 penetrates the workpiece 111 in advance and is supported at two points above and below it, the influence of the machining liquid pressure is relatively small. Further, since the machining fluid flows into the formed machining groove 114, sludge can be easily discharged.

  However, in the drilling process that is the subject of the present invention, the electrode is supported at one point as shown in FIG. In particular, as shown in FIG. 8B, when the gap L2 between the wire guide 112 and the workpiece 111 is large, the protruding amount of the electrode is large. In addition, it is necessary to secure a discharge path for the ejected machining fluid and sludge. If the gap L1 between the workpiece 111 and the workpiece 111 is increased, the protruding amount of the electrode is further increased, and the effect of suppressing the deflection and vibration of the electrode is expected. Can not.

  The present invention pays attention to such a situation, and in an electric discharge machining apparatus for electric discharge machining of fine pores on a workpiece, the deflection and deflection of the electrode are suppressed, and the machining variation of the machining hole diameter is reduced. It is an object of the present invention to provide an electric discharge machining apparatus that can improve machining accuracy and that is capable of high-efficiency and high-quality fine hole machining without complicated control and an increase in the number of machining steps.

According to the first aspect of the present invention, there is provided an elongated electrode facing a work to be processed with pores, an electrode guide through which the electrode is inserted and held, and a voltage between the electrode and the work. In an electric discharge machining apparatus having a voltage application means for applying and a machining liquid supply means for supplying a machining liquid to a workpiece portion of the workpiece,
The machining liquid supply means, the distal end surface is disposed on the outer periphery of the electrode guide is provided with a hollow working fluid guide member you close position to the workpiece, while the hollow portion and the reservoir working fluid, the distal end The surface is provided with an opening that communicates with the processing liquid reservoir and into which the tip of the electrode guide is inserted, and the tip of the electrode guide projects from the tip of the opening to the workpiece side, and the electrode Between the tip outer peripheral surface of the guide and the inner peripheral surface of the opening, an annular machining liquid ejection path having a smaller outer diameter toward the workpiece is formed .
A distance b between the machining fluid guide member and the workpiece is set larger than a distance a between the electrode guide and the workpiece, thereby forming a machining fluid discharge path .

In the invention according to claim 2 of the present invention, specifically, the outer peripheral surface of the tip portion of the electrode guide and the inner peripheral surface of the opening are formed as a tapered surface that decreases in diameter toward the workpiece, and both tapered surfaces are provided. The annular space formed between the two is defined as the above-described machining liquid ejection path in which the flow path area decreases toward the downstream side and the machining liquid is accelerated and ejected .

  In the invention described in claim 3 of the present invention, both the tapered surfaces of the electrode guide and the opening are set to a taper angle at which the machining point of the workpiece is located on an extension line of the machining liquid ejection path.

In the invention according to claim 4 of the present invention, the electrode guide has a tapered surface on the outer peripheral surface of the tip portion formed of two surfaces having different taper angles, and the taper angle on the workpiece side is further increased to obtain a machining fluid. Accelerate the flow .

  In the invention according to claim 5 of the present invention, the hollow portion serving as the machining fluid pool is an outer peripheral surface of the electrode guide between the holding portion of the electrode guide provided in the machining fluid guide member and the opening. Is provided with a machining fluid inlet for introducing a machining fluid from the outside into the annular space.

  In the invention according to claim 6 of the present invention, a rectifying plate having a plurality of machining fluid circulation holes is arranged in the machining fluid reservoir, the interior of which is partitioned in the axial direction of the electrode guide.

  In the invention according to claim 7 of the present invention, the electrode is a fine wire electrode having a diameter of 150 μm or less.

  According to the electric discharge machining apparatus of the first aspect of the present invention, since the machining fluid ejection path is provided between the electrode guide and the machining fluid guide member and the machining fluid is supplied to the workpiece from the axial direction of the electrode, Less susceptible to machining fluid pressure. In addition, since the electrode guide protrudes from the machining fluid guide member, the electrode can be disposed close to the workpiece, and the deflection and vibration of the electrode can be prevented. In addition, a machining fluid pool is provided inside the machining fluid guide member, and sufficient machining fluid is supplied to the machining fluid ejection path, and the machining fluid accelerated by the machining fluid ejection path whose diameter is reduced toward the workpiece side is supplied to the workpiece. Centralized supply to the processing site.

  Therefore, it is possible to reduce the machining variation of the machining hole diameter at the time of electric discharge machining of the fine hole in the workpiece and improve the machining accuracy. Further, since complicated control is not required and pilot hole machining is unnecessary, high-quality fine hole machining can be performed efficiently.

  Specifically, as in the second aspect of the present invention, specifically, the tip portion of the electrode guide and the opening portion of the machining liquid guide member are each formed into a tapered surface, so that machining can be easily performed between them. A liquid ejection path can be formed.

  As in the invention described in claim 3 of the present invention, it is preferable to appropriately set the tapered surface of the electrode guide and the tapered surface of the machining fluid guide member so that the workpiece is machined on the extended line of the machining fluid ejection path. It is possible to effectively supply the machining liquid to the machining point of the workpiece by arranging the points.

  As in the invention according to claim 4 of the present invention, the tip tapered surface of the electrode guide does not have a constant taper angle. For example, by increasing the taper angle of the tip, the flow of the machining liquid is set as the machining point. It can be made easier to converge.

  Specifically, as in the invention described in claim 5 of the present invention, the machining liquid is provided around the electrode guide between the two parts by providing the machining liquid guide member with an electrode guide holding portion facing the opening. An annular space serving as a pool can be easily formed. Further, the machining liquid can be easily introduced from the outside through the machining liquid introduction port.

  According to the sixth aspect of the present invention, the current plate is installed in the working fluid pool. It is possible to flow the processing liquid evenly from the processing liquid pool into the opening, thereby enhancing the effect of preventing the deflection and vibration of the electrode, and to suppress processing variations.

  As in the seventh aspect of the present invention, preferably, in an electric discharge machining apparatus that is a thin wire electrode having an electrode diameter of 150 μm or less, the effect of applying the present invention is particularly high, and machining of fine holes is highly performed. It can be formed with accuracy.

BRIEF DESCRIPTION OF THE DRAWINGS It is 1st Embodiment of this invention, (a) is an expanded sectional view which shows the principal part structure of an electrical discharge machining apparatus, (b) is a partial cross section which shows the whole structure of the fuel-injection nozzle processed by this apparatus. FIG. (A) is a whole schematic block diagram of the electric discharge machining apparatus of 1st Embodiment. It is principal part sectional drawing of the electrical discharge machining apparatus for demonstrating the electrical discharge machining method using the electrical discharge machining apparatus of this invention, and an effect. (A)-(c) is the schematic for demonstrating the electric discharge machining process by the electric discharge machining apparatus of this invention. (A) is an expanded sectional view which shows the principal part structure of the electrical discharge machining apparatus in 2nd Embodiment of this invention, (b) is an expanded cross section which shows the principal part structure of the electrical discharge machining apparatus in 3rd Embodiment of this invention. FIG. (A) is an expanded sectional view which shows the principal part structure of the electric discharge machining apparatus in 4th Embodiment of this invention, (b) is the A section expanded sectional view of (a). (A) is an expanded sectional view which shows the principal part structure of the electrical discharge machining apparatus in 5th Embodiment of this invention, (b) is an expanded cross section which shows the principal part structure of the electrical discharge machining apparatus in 6th Embodiment of this invention. FIG. (A) is the whole schematic block diagram of the conventional electric discharge machining apparatus, (b) is a principal part expanded sectional view of the conventional wire electric discharge machining apparatus. (A) is a figure for demonstrating the electric discharge machining method by the conventional electric discharge machining apparatus, (b), (c) is a figure for demonstrating the subject in the conventional electric discharge machining apparatus.

  Hereinafter, a first embodiment of the present invention will be described in detail with reference to the drawings. The electric discharge machining apparatus of the present invention is an apparatus for machining fine pores (hereinafter referred to as fine pores as appropriate) on various workpieces (workpieces), and this embodiment is for an automobile diesel engine. It is an example applied to the injection hole machining of the fuel injection nozzle constituting the injector. FIG. 1A is a cross-sectional view showing a main part configuration of an electric discharge machining apparatus, and FIG. 1B is an overall configuration diagram of a fuel injection nozzle which is a workpiece machined by the apparatus, and a front half portion. Is shown as a cross section. FIG. 2 is an overall configuration diagram of the electric discharge machining apparatus. First, a schematic configuration of the electric discharge machining apparatus 1 will be described based on this drawing.

  In FIG. 2, an electric discharge machining apparatus 1 includes an electric discharge machining head H that sends an elongated electrode 11 toward a workpiece W, a pedestal 12 on which the workpiece W is placed, and an XY for positioning the workpiece W and the pedestal 12. A table T, a guide part G for guiding the electrode 11, a power supply device B serving as a voltage applying means for applying a voltage between the electrode 11 and the workpiece W, and a machining liquid for supplying a machining liquid to the machining part Supply means are provided. The electric discharge machining head H includes a rotation mechanism and a feed mechanism for the electrode 11 (not shown) inside, and feeds the electrode 11 downward while rotating the electrode 11 as the machining progresses. Further, the approach shaft 13 that supports the electric discharge machining head H can drive the electric discharge machining head H in the vertical direction of the drawing together with the approach shaft 13 by the drive unit 14.

  One end of the guide portion G, which is arm-shaped, is supported by the approach shaft 13, and the electrode 11 is inserted and held in the electrode guide 2 provided on the other end. The machining liquid supply means includes a machining liquid guide 3 as a machining liquid guide member disposed around the electrode guide 2 of the guide portion G, and a machining liquid supply path 31 connected to the machining liquid guide 3. The machining fluid supply path 31 communicates with a machining fluid storage tank (not shown) and supplies the machining fluid to the machining fluid guide 3 by driving a pump (not shown). The detailed configuration of the guide part G and the machining fluid supply means will be described later.

  The workpiece W is arranged on the XY table T in a state where the workpiece W is held and fixed in a predetermined posture on the mounting surface of the base 12. The XY table T includes a drive mechanism that can arbitrarily move in the X and Y directions, and the workpiece W is positioned so that the machining portion of the workpiece W is collinear with the axis of the electrode 11 protruding from the electric discharge machining head H. Is moved relative to the electrode 11 to be positioned at a predetermined position. The positive terminal of the power supply device B is connected to the electrode 11, and the negative terminal is connected to the workpiece W.

  As shown in FIG. 1 (a), the electrode guide 2 provided in the guide portion G has a conical tip portion 21 following the main body portion having a constant diameter, and the guide through which the electrode 11 is inserted along the central axis. It consists of a substantially cylindrical body with a hole 22 formed therethrough. The electrode 11 is a thin wire made of a soft metal material such as tungsten or copper, and usually has a diameter of 150 μm or less, and preferably has a diameter of 40 to 120 μm. The electrode guide 2 is made of ceramics, and the guide hole 22 is formed slightly larger than the electrode 11 and guides it while holding the rotating electrode 11.

  The nozzle body 4 of the fuel injection nozzle, which is the workpiece W, is arranged facing the traveling direction of the electrode 11 (downward in the figure), and the position of the injection hole 41 is adjusted so that it is on the axis of the electrode 11. The As shown in FIG. 1B, the nozzle body 4 of the fuel injection nozzle has a semicircular sac portion 43 at the top of a conical tip portion (upper end portion in the figure), and this sack portion 43 wall is It has a plurality of injection holes 41 that penetrate therethrough. The cylinder of the nozzle body 4 serves as a fuel flow path and accommodates a nozzle needle (not shown). The nozzle needle is raised and lowered with the tapered surface of the inner wall of the tip end as a valve seat, thereby opening and closing the nozzle hole 41.

  In FIG. 1A, the configuration of the machining fluid supply means of the present invention will be described. The machining fluid supply means of the present invention includes a machining fluid guide 3 provided integrally with the electrode guide 2. The machining liquid guide 3 has a hollow and substantially container shape and is disposed so as to surround the outer periphery of the electrode guide 2. The hollow portion of the machining liquid guide 3 is an annular space formed between the outer peripheral surface of the electrode guide 2 and constitutes a machining liquid pool 32. A machining fluid introduction port 33 penetrating the side wall of the machining fluid guide 3 is opened in the machining fluid reservoir 32, and the machining fluid supply path 31 shown in FIG. 2 is connected to introduce the machining fluid (for example, pure water). It is like that.

  On the front end surface of the machining liquid guide 3 (the lower surface in FIG. 1A), an opening 34 having a diameter decreasing downward is provided in the center, and the front end portion 21 of the electrode guide 2 is inserted. The tip 21 has a conical shape with a diameter decreasing downward, protrudes toward the workpiece W below the opening 34, and a flat tip surface is located close to the nozzle body 4 of the fuel injection nozzle that is the workpiece W. ing. As a result, the electrode 11 protruding from the tip 21 of the electrode guide 2 is positioned directly above the portion of the nozzle body 4 where the nozzle hole 41 is processed.

  In the present invention, the machining liquid ejection path 35 is formed between the tapered surface of the outer periphery of the tip 21 of the electrode guide 2 and the tapered surface of the inner periphery of the opening 34 of the machining liquid guide 3. The machining fluid ejection passage 35 is an annular space surrounded by both tapered surfaces arranged concentrically, and the inner and outer diameters become smaller toward the workpiece W side. Thereby, since the flow path area of the machining liquid ejection path 35 becomes smaller toward the downstream side, the flow of the machining liquid flowing into the machining liquid ejection path 35 is accelerated while moving toward the axial center as shown in the figure, and the electrode 11 erupts around.

  Accordingly, by adjusting the shape of the machining liquid ejection path 35, the protruding amount of the tip portion 21 of the electrode guide 2, the distance between the electrode guide 2 and the workpiece W, etc. so that this flow converges at the machining point, The liquid can be concentrated at the processing point. Specifically, by adjusting the distance and taper angle between the tapered surface of the outer periphery of the tip 21 of the electrode guide 2 and the tapered surface of the inner periphery of the opening 34 of the machining fluid guide 3, the flow path area, flow velocity, and convergence are adjusted. The point can be adjusted.

  Specifically, as shown in FIG. 1A, in the present embodiment, both tapered surfaces of the electrode guide 2 and the machining fluid guide 3 are formed so that the taper angles are substantially equal. However, the present invention is not limited to this, and by providing a tapered surface at least on the inner periphery of the opening 34 of the machining liquid guide 3 to form an annular space having a smaller outer diameter toward the workpiece W side, the machining liquid ejection path 35 is formed. The same effect can be obtained by reducing the flow path area and converging the flow.

  A cylindrical holding member 36 serving as a holding portion is fitted and fixed to the upper end opening of the working fluid guide 3 between the electrode guide 2 and the upper end opening. The outer periphery of the lower end of the cylindrical holding member 36 is supported by a step provided in the upper end opening of the machining fluid guide 3, and a seal member 37 is interposed. As a result, the upper end portion of the electrode guide 2 is tightly held in the cylinder of the cylindrical holding member 36, and the liquid tightness of the processing liquid reservoir 32 formed between the cylindrical holding member 36 and the opening 43 is ensured. The

  Here, the annular space serving as the machining fluid pool 32 has a sufficiently large capacity and outer diameter with respect to the opening 34 serving as the machining fluid ejection path 35, and the opening 34 extends from the entire annular bottom surface of the machining fluid pool 32. It is preferable that the processing liquid can be supplied evenly. Further, the machining fluid guide 3 has a tapered surface whose outer diameter is reduced downward, and has a shape that facilitates discharge of machining fluid including sludge while ensuring a distance from the nozzle body 4 that is the workpiece W. Preferably, the distance between the tip portion 21 of the electrode guide 2 and the opening 34 of the machining liquid guide 3 constituting the machining liquid ejection path 35 may be in the range of 0.3 to 0.5 mm. Concentrate and facilitate sludge discharge.

  Next, based on FIGS. 3 and 4, an electric discharge machining method using the electric discharge machining apparatus 1 having the above-described configuration and its operation and effect will be described. In FIG. 3, the structure of the electric discharge machining apparatus 1 is the same as that of FIG. 1, and the fine holes W1 are machined into the workpieces W arranged to face each other. FIG. 4 is an enlarged view showing a process of electric discharge machining while feeding the electrode 11 by the electric discharge machining head H of FIG.

  First, in FIG. 3, the electrode guide 2, the machining fluid guide 3, and the workpiece W are positioned at a predetermined machining start position. For this purpose, the XY table T in FIG. 2 is operated to position the work W together with the base 12 in a predetermined position and posture, and the approach shaft 13 is driven by the drive unit 14 to drive the electrode guide 2 and the work. The electric discharge machining head H is lowered to a height at which the distance a between W is a predetermined distance a.

  In the present invention, since the electrode guide 2 protrudes from the machining fluid guide 3 toward the workpiece W, the distance b between the machining fluid guide 3 and the workpiece W is larger than the predetermined distance a (distance b> distance a). . In other words, the distance b can be made sufficiently wide to secure a sludge discharge path by machining, while the distance a can be made narrower than before to reduce the amount of protrusion of the electrode 11 from the electrode guide 2 necessary for discharge. Specifically, the predetermined distance a can be reduced from, for example, the conventional 0.3 mm to about 0.2 mm, and the effect of preventing the cantilevered electrode 11 from shaking can be obtained.

  At the start of processing, as shown in FIG. 4A, the tip of the electrode 11 is positioned so as to be flush with the tip surface of the electrode guide 2. Next, a voltage is applied between the workpiece W and the electrode 11 by the power supply device B, and the electrode feed is started by a necessary length while rotating the electrode 11 by the rotation and feed mechanism built in the electric discharge machining head H. . Prior to this, a pump (not shown) is driven to supply the machining fluid from the machining fluid supply path 31 to the machining fluid reservoir 32 in the machining fluid guide 3.

  As shown in FIGS. 4B and 4C, when the electrode 11 approaches the workpiece W up to a predetermined discharge gap Ga, a discharge is generated between the two, and the surface of the workpiece W is gradually melted to form the fine hole W1. Is processed. The feeding amount at this time may be slightly larger than the predetermined distance a and the length corresponding to the thickness c of the workpiece W. During the electric discharge machining, the machining liquid is ejected from the machining liquid ejection path 35 following the machining liquid pool 32. The machining liquid is accelerated by the machining liquid ejection path 35 that gradually decreases in diameter, and is concentrated and supplied to the machining point along the tapered surface of the electrode guide 2. Sludge generated by electric discharge machining is discharged together with the machining fluid as indicated by the arrows in FIG.

  Thus, in the present invention, since the machining fluid is supplied from the axial direction, it is possible to prevent the pressure of the machining fluid from being applied to the electrode 11 from the lateral direction. Further, since the electrode guide 2 is close to the workpiece W, even if the electrode 11 has a fine diameter, it is difficult to cause deflection and vibration. Moreover, since the machining fluid is supplied so as to converge at the machining point, the machining fluid can be efficiently supplied to the machining point until the fine hole W1 penetrates the workpiece W, and the generated sludge can be easily discharged. It is. Therefore, variations in the processing hole diameter can be suppressed, and processing accuracy can be greatly improved. Further, since the machining can be performed efficiently without requiring complicated control or the like, the manufacturing cost is not increased.

  FIG. 5 shows the second and third embodiments of the present invention. FIG. 5A is an enlarged sectional view showing the configuration of the main part of the electric discharge machining apparatus 1 according to the second embodiment, and FIG. 5B is an enlarged view of the configuration of the main part of the electric discharge machining apparatus 1 according to the third embodiment. It is sectional drawing shown. Since the other basic configurations of the second and third embodiments are the same as those of the first embodiment, the same reference numerals are given to the same members. Hereinafter, the difference will be mainly described.

  In the second embodiment shown in FIG. 5A, the rectifying plate 5 is disposed in the working fluid pool 32 in the first embodiment. The rectifying plate 5 is composed of an annular plate surface 51 that divides the inside of the processing liquid reservoir 32 up and down and leg portions 52 provided on the outer peripheral portion of the lower surface thereof. Is formed. A large number of machining fluid inflow holes 53 of the rectifying plate 5 have a hole diameter and a hole so that the total flow passage area is sufficiently larger than the flow passage area of the inlet portion (the machining fluid reservoir 32 side) of the machining fluid ejection passage 35. Set the number. In the machining liquid ejection path 35, the distance between the tip 21 of the electrode guide 2 and the opening 34 of the machining liquid guide 3 is set to a range of, for example, 0.3 to 0.5 mm.

  As a result, the machining fluid flowing from the machining fluid introduction port 33 that opens to the side surface into the machining fluid reservoir 32 passes through the rectifying plate 5 to become an axial flow, and is evenly distributed in the lower half of the machining fluid reservoir 32. Inflow. Therefore, the flow of the machining fluid passing through the machining fluid ejection path 35 can be made more uniform, the influence on the electrode 11 can be reduced, and the machining accuracy can be further improved.

  In the third embodiment shown in FIG. 5B, the shape of the machining fluid guide 3 in the first embodiment is changed according to the shape of the workpiece W. For example, in a fuel injection device for a diesel engine, a part of a flow path in an injector is a fine orifice flow path. In the present embodiment, a flow path forming member that forms such a flow path is a workpiece W, and a small diameter hole W2 that becomes a flow path and a minute hole W1 that becomes an orifice are processed in the work W.

  For this reason, the machining liquid guide 3 is provided with a conical projection 38 having a diameter that decreases downward in the center of the tip surface, and the tip portion 21 of the electrode guide 2 is inserted into the projecting portion 38 so that the machining liquid ejection path is provided. 35 is formed. The outer diameter of the projecting portion 38 is made smaller than the small diameter hole W2 of the workpiece W, and the projecting length of the projecting portion 38 is such a length that the electrode 11 projecting from the tip portion 21 of the electrode guide 2 reaches the bottom surface of the small diameter hole W2. . As described above, the shape of the machining fluid guide 3 can be changed according to the shape of the workpiece W to be processed, and the minute hole W1 communicating with the small diameter hole W2 can be processed by the same electric discharge machining method. it can. Since the machining fluid can be directly supplied to the machining point at the bottom of the small-diameter hole W2, efficient machining is possible and sludge is discharged well.

  FIG. 6 shows a fourth embodiment of the present invention. FIG. 6A is an enlarged cross-sectional view of a main part of the electric discharge machining apparatus 1 according to the fourth embodiment, and FIG. This embodiment is based on the second embodiment described above, and the shapes of the electrode guide 2 and the machining fluid guide 3 are changed. Hereinafter, the differences will be mainly described.

  As shown in FIGS. 6A and 6B, in this embodiment, the rectifying plate 5 is disposed in the working fluid pool 32. Further, the tapered tip portion 21 of the electrode guide 2 changes the taper angle of the taper surface between a portion located in the machining liquid ejection path 35 and a protruding portion 23 protruding from the machining liquid guide 3. The taper angle of the outer peripheral surface of the protrusion 23 is further increased. Thereby, the diameter of the projecting portion 23 is further reduced toward the workpiece W side, and the flow of the machining liquid is easily concentrated on the center. Further, in the machining liquid guide 3, the taper angle of the inner peripheral surface of the opening 34 is slightly larger than the taper angle of the outer peripheral surface of the opposing electrode guide 2. As a result, the distance between the two tapered surfaces constituting the machining fluid ejection path 35 is wide on the inlet side and narrow on the workpiece W side on the outlet, and the flow of the machining fluid is further accelerated.

  As described above, in this embodiment, the flow of the machining liquid ejected from the machining liquid ejection path 35 is easily converged by the machining point of the workpiece W and the flow velocity is increased, so that the sludge is discharged well and the electric discharge machining is performed. Can be implemented more efficiently.

  FIG. 7 shows fifth and sixth embodiments of the present invention. The configuration of the electric discharge machining apparatus 1 in these embodiments is the same as that in the first embodiment, and the workpiece W to be machined is changed. In each said embodiment, although the example of application to the components processing of the fuel-injection apparatus of a diesel engine was shown, this invention can be used suitably also for the hole processing of components other than these. For example, the fifth embodiment in FIG. 7A is an application example to an electrolytic processing apparatus, and uses an electrolytic solution injection electrode 6 for electrolytic processing as a work W. The electrolyte injection electrode 6 has a large number of injection holes 61 on the entire cylindrical surface of the cylindrical body, and machining these injection holes 61 with the electric discharge machining apparatus 1 of the present invention reduces the variation in the processing hole diameter. It is possible to manufacture the electrolyte solution injection electrode 6 that is small in size and excellent in electrolyte solution injection performance.

  Needless to say, the present invention can be applied to not only a diesel engine but also a fuel injection device of a gasoline engine to drill holes in various parts. In the sixth embodiment shown in FIG. 7B, the fuel injection nozzle 7 of the gasoline engine is used as a work W, and the nozzle hole 71 at the tip of the nozzle is processed by the electric discharge machining apparatus 1 of the present invention. The present invention can be applied not only to the injection hole 71 but also to processing an orifice hole in the flow path component of the fuel injection device, or to processing a fine hole in the filter member disposed in the fuel supply passage. With the electric discharge machining apparatus 1 of the invention, high machining accuracy can be realized and quality can be improved.

  The present invention is to process not only a fuel injection device for a vehicle engine but also fine pores (for example, 150 μm or less) that require high processing accuracy such as nozzle holes, orifice holes, and filter holes of nozzles for various devices. It is suitable for. Moreover, since the fine holes machined by the electric discharge machining apparatus of the present invention have small machining variations, they are extremely useful in the processing of members having a large number of fine holes or the method of continuously machining a large number of fine holes.

B Power supply (voltage application means)
G Guide part H Electric discharge machining head TXY table W Workpiece 1 Electrical discharge machining apparatus 11 Electrode 12 Base 2 Electrode guide 21 Tip part 22 Guide hole 3 Working fluid guide (machining fluid guide member)
31 Working fluid supply path 32 Working fluid reservoir 33 Working fluid introduction port 34 Opening portion 35 Working fluid ejection passage 4 Fuel injection nozzle 41 Nozzle body 42 Tip portion 43 Suck portion 5 Rectification plate 51 Working fluid inflow hole

Claims (7)

An elongated electrode facing the workpiece to be processed with pores, an electrode guide through which the electrode is inserted and supported, a voltage applying means for applying a voltage between the electrode and the workpiece, and a workpiece to be processed of the workpiece In an electric discharge machining apparatus having a machining liquid supply means for supplying a machining liquid to a site,
The machining liquid supply means, the distal end surface is disposed on the outer periphery of the electrode guide is provided with a hollow working fluid guide member you close position to the workpiece, while the hollow portion and the reservoir working fluid, the distal end The surface is provided with an opening that communicates with the processing liquid reservoir and into which the tip of the electrode guide is inserted, and the tip of the electrode guide projects from the tip of the opening to the workpiece side, and the electrode Between the tip outer peripheral surface of the guide and the inner peripheral surface of the opening, an annular machining liquid ejection path having a smaller outer diameter toward the workpiece is formed .
An electrical discharge machining apparatus characterized in that a machining fluid discharge path is formed by setting a distance b between the machining fluid guide member and the workpiece to be larger than a distance a between the electrode guide and the workpiece . The outer peripheral surface of the distal end portion of the electrode guide and the inner peripheral surface of the opening are formed as a tapered surface that is reduced in diameter toward the workpiece side, and an annular space formed between both tapered surfaces has a flow path area closer to the downstream side. The electric discharge machining apparatus according to claim 1, wherein the machining liquid ejection path is made smaller and the machining liquid is accelerated and ejected .   The electric discharge machining apparatus according to claim 2, wherein both tapered surfaces of the electrode guide and the opening are set to a taper angle at which a machining point of the workpiece is located on an extension line of the machining liquid ejection path. The electrode guide is, the tapered surface of the distal end portion outer peripheral surface, constituted by two surfaces with different taper angle, the work-side larger to working fluid accelerated was Ru claim 2 or 3, wherein the flow of the taper angle of EDM machine.   The hollow portion serving as the working fluid pool is an annular space surrounding the outer peripheral surface of the electrode guide between the holding portion of the electrode guide provided in the working fluid guide member and the opening, and the outer space is external to the annular space. The electric discharge machining apparatus according to any one of claims 1 to 4, further comprising a machining fluid inlet for introducing the machining fluid.   The electric discharge machining apparatus according to any one of claims 1 to 5, wherein the machining liquid reservoir is partitioned in an axial direction of the electrode guide, and a rectifying plate having a plurality of machining liquid flow holes is disposed.   The electric discharge machining apparatus according to claim 1, wherein the electrode is a thin wire electrode having a diameter of 150 μm or less.

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