WO2005018858A1 - 放電加工方法 - Google Patents
放電加工方法 Download PDFInfo
- Publication number
- WO2005018858A1 WO2005018858A1 PCT/JP2004/012195 JP2004012195W WO2005018858A1 WO 2005018858 A1 WO2005018858 A1 WO 2005018858A1 JP 2004012195 W JP2004012195 W JP 2004012195W WO 2005018858 A1 WO2005018858 A1 WO 2005018858A1
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- WIPO (PCT)
- Prior art keywords
- electrode
- machining
- hole
- workpiece
- axis
- Prior art date
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Classifications
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23H—WORKING OF METAL BY THE ACTION OF A HIGH CONCENTRATION OF ELECTRIC CURRENT ON A WORKPIECE USING AN ELECTRODE WHICH TAKES THE PLACE OF A TOOL; SUCH WORKING COMBINED WITH OTHER FORMS OF WORKING OF METAL
- B23H7/00—Processes or apparatus applicable to both electrical discharge machining and electrochemical machining
- B23H7/26—Apparatus for moving or positioning electrode relatively to workpiece; Mounting of electrode
- B23H7/265—Mounting of one or more thin electrodes
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23H—WORKING OF METAL BY THE ACTION OF A HIGH CONCENTRATION OF ELECTRIC CURRENT ON A WORKPIECE USING AN ELECTRODE WHICH TAKES THE PLACE OF A TOOL; SUCH WORKING COMBINED WITH OTHER FORMS OF WORKING OF METAL
- B23H1/00—Electrical discharge machining, i.e. removing metal with a series of rapidly recurring electrical discharges between an electrode and a workpiece in the presence of a fluid dielectric
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23H—WORKING OF METAL BY THE ACTION OF A HIGH CONCENTRATION OF ELECTRIC CURRENT ON A WORKPIECE USING AN ELECTRODE WHICH TAKES THE PLACE OF A TOOL; SUCH WORKING COMBINED WITH OTHER FORMS OF WORKING OF METAL
- B23H7/00—Processes or apparatus applicable to both electrical discharge machining and electrochemical machining
- B23H7/26—Apparatus for moving or positioning electrode relatively to workpiece; Mounting of electrode
- B23H7/28—Moving electrode in a plane normal to the feed direction, e.g. orbiting
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23H—WORKING OF METAL BY THE ACTION OF A HIGH CONCENTRATION OF ELECTRIC CURRENT ON A WORKPIECE USING AN ELECTRODE WHICH TAKES THE PLACE OF A TOOL; SUCH WORKING COMBINED WITH OTHER FORMS OF WORKING OF METAL
- B23H9/00—Machining specially adapted for treating particular metal objects or for obtaining special effects or results on metal objects
- B23H9/10—Working turbine blades or nozzles
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23H—WORKING OF METAL BY THE ACTION OF A HIGH CONCENTRATION OF ELECTRIC CURRENT ON A WORKPIECE USING AN ELECTRODE WHICH TAKES THE PLACE OF A TOOL; SUCH WORKING COMBINED WITH OTHER FORMS OF WORKING OF METAL
- B23H9/00—Machining specially adapted for treating particular metal objects or for obtaining special effects or results on metal objects
- B23H9/14—Making holes
Definitions
- the present invention relates to a discharge pump method, and more particularly to a discharge pump method for forming a narrow hole or the like formed obliquely with respect to the surface of an object to be caulked using trajectory control by an NC device. It relates to the method.
- a conventional electric discharge machining method disclosed in Patent Document 1 is a method of generating an electrode by scanning an electrode, and the shallow cavity is maintained while maintaining the flatness of the bottom surface of the electrode under consumable processing conditions.
- (Concave) Shape is processed.
- the machining shape is arbitrary in the plane, but in the depth direction, it is a 2.5-dimensional shape combining planes.
- the offset value with respect to the in-plane target shape is finely adjusted to form a tapered shape on the side surface, but the feed pitch for engraving in the Z-axis direction when machining the tapered shape is smaller than the electrode diameter.
- Patent Document 1 Patent No. 3395431
- the above-mentioned conventional scanning generation electric discharge machining method is effective for machining a cavity (concave shape) having a large area with respect to the electrode diameter. For example, a diffuser hole (diffuser hole) is required. ), It is difficult to machine small holes with different shapes or sizes of hole entrance and hole exit.
- a taper is formed on a side surface by fine adjustment of an offset amount in plane machining, so that a tapered hole portion has a stepped shape, and a feed pitch with respect to an electrode diameter is increased. There is a problem that the processing time becomes longer due to the smaller size.
- the shape targeted by the conventional scanning generating and discharging method is perpendicular to the surface of the workpiece, and machining is performed by setting the surface of the workpiece horizontally.
- machining is performed by setting the surface of the workpiece horizontally.
- the present invention has been made in view of the above, and has been made in consideration of the above, and has a discharge capping method capable of efficiently processing an irregularly shaped fine hole formed to be inclined with respect to the surface of the object.
- the purpose is to provide.
- the discharge method according to the present invention provides a method of applying a voltage between an electrode and a workpiece while applying a voltage between the electrode and the workpiece.
- a specially shaped narrow hole that is inclined with respect to the surface of the workpiece is formed.
- a positioning holding step for holding the workpiece in a tilted manner so that one inner surface of a target machining shape of the straight hole portion of the irregularly shaped small hole is parallel to the Z axis.
- the electric discharge machining method of the present invention when the workpiece is fixed to the electric discharge machining apparatus in the positioning and holding step, one inner surface of the target machining shape of the straight hole portion of the irregularly shaped small hole is formed.
- the workpiece is tilted and held so that the workpiece and the Z axis are parallel to each other.
- a conventional electrode extending in the Z axis direction, first, engrave the electrode in the z axis direction by a predetermined amount, and then The electrode is moved along the target machining shape contour in the XY plane, and then the electrode is further engraved in the Z-axis direction by a predetermined amount, and then the electrode is similarly moved along the target machining shape contour in the XY plane.
- the deformed fine hole is carved, so that even a deformed fine hole having a rectangular tapered hole portion and a straight hole portion formed obliquely to the surface of the workpiece is formed. It can be processed efficiently.
- FIG. 1 is a diagram showing a configuration of an electric discharge machining apparatus for realizing an electric discharge machining method according to a first embodiment of the present invention.
- FIG. 2_1 is a front view of the workpiece support means in the details of the workpiece support means of the electric discharge machine of FIG.
- FIG. 2_2 is a side view of the force-feeding material support means in the drawing showing details of the force-feeding material support means of the electric discharge kettle apparatus of FIG.
- FIG. 3-1 is a diagram showing details of a differential user hole as an irregularly shaped fine hole formed by the electric discharge method according to the first embodiment of the present invention. Is a front view of the diff user hall.
- FIG. 3-2 is a cross-sectional view taken along a line AA of FIG. 3-1 among the details showing the diff user hole.
- FIG. 3-3 is a cross-sectional view taken along the line BB of FIG. 3-1 among the details showing the diff user hole.
- FIG. 4 is a view showing a state in which the object to be treated is inclined and fixed to the discharge container.
- FIG. 5 is a diagram showing a scanning trajectory near an opening of a rectangular tapered hole portion.
- FIG. 6 is a diagram showing a scanning locus at the center of a rectangular tapered hole.
- FIG. 7 is a diagram showing a scanning trajectory over the entire rectangular tapered hole.
- FIG. 8 is an explanatory view showing a relationship between a rectangular tapered hole and an electrode cross section.
- FIG. 9 is a diagram showing a scanning trajectory at an entrance of a straight portion.
- FIG. 10 is a diagram showing a scanning trajectory over the entire straight portion.
- FIG. 11 is an explanatory diagram showing a relationship between a hole cross section and an electrode diameter.
- FIG. 12 is a diagram illustrating a rough discharge process using a long pulse low peak waveform current for explaining a discharge control method according to a second embodiment of the present invention. After the rough discharge process, a short pulse waveform process is performed.
- FIG. 4 is a perspective view showing a scanning trajectory when finishing discharge using a flow.
- FIG. 13 is a sectional view showing a state of a section after rough electric discharge machining.
- FIG. 14 is a cross-sectional view showing a state of a cross section after finish electric discharge machining.
- FIG. 15-1 is a front view of a straight pilot hole, showing a state in which a direct pilot hole is machined for explaining the electric discharge machining method according to Embodiment 3 of the present invention. .
- FIG. 15-2 is a cross-sectional view taken along the line AA of FIG.
- FIG. 15-3 is a cross-sectional view taken along the line BB of FIG.
- FIG. 16-1 is a diagram schematically illustrating a processing locus when a diffuser hole is created by scanning an electrode as a second procedure after processing a straight prepared hole 55.
- FIG. 3 is a front view of a diff user hole.
- FIG. 16-2 is a cross-sectional view along A_A in FIG. 16-1.
- FIG. 16-3 is a sectional view taken along line BB of FIG. 16-1.
- FIG. 17 is a flowchart illustrating an automatic continuous machining procedure for a large number of holes in the electric discharge method according to Embodiment 4 of the present invention.
- FIG. 18 is a graph showing a relationship between an electrode protrusion length and a machining time for explaining an electric discharge machining method according to a fifth embodiment of the present invention.
- FIG. 19 is a diagram showing a procedure for controlling the electrode rotation speed.
- FIG. 20-1 is a cross-sectional view showing one example of a positional relationship between a tapered hole and an electrode for explaining an electric discharge machining method according to a sixth embodiment of the present invention.
- FIG. 20-2 is a cross sectional view showing another example of the positional relationship between the tapered hole and the electrode for explaining the electrical discharge machining method according to Embodiment 6 of the present invention.
- FIG. 20-3 is a cross sectional view showing another example of the positional relationship between the tapered hole and the electrode for explaining the electrical discharge machining method according to Embodiment 6 of the present invention.
- FIG. 1 is a diagram showing a configuration of an electric discharge machining apparatus for realizing an electric discharge machining method according to Embodiment 1 of the present invention.
- FIGS. 2-1 and 2-2 are diagrams showing details of the workpiece support means of the electric discharge machine of FIG. 1, and FIG. 2_1 is a front view of the workpiece support means, and FIG. FIG. 4 is a side view of a workpiece support means.
- the electric discharge machining apparatus supports the workpiece 1 and supports the C-axis table 2 rotating around the C-axis and the C-axis table 2.
- a B-axis table 3 that rotates around the B-axis; and a bed 4 that supports the B-axis table 3.
- the electric discharge machining apparatus includes an electrode 5 for generating electric discharge between the workpiece 1, an electrode holder 6 for holding the electrode 5, and a tip position of the electrode 5 near the workpiece 1.
- Guide 7 for determining the position a chuck 8 for holding the electrode holder 6, a head 9 for supporting the chuck 8 and moving in parallel in the Z-axis direction, and a head 9 for supporting the head 9 and moving in the X-axis and Y-axis directions.
- a ram 10 and a processing tank 11 for immersing the workpiece 1 with a processing liquid are provided.
- the processing tank 11 and the ram 10 are supported by the bed 4.
- the electric discharge machining device has an NC control device 12 as a control device for controlling each of the C-axis table 2, the B-axis table 3, the head 9, and the ram 10.
- the NC controller 12 includes an NC data section 13 for storing a target machining shape as NC data in advance, and a position control for controlling the C-axis table 2, the B-axis table 3, the head 9, and the ram 10 based on the NC data.
- NC position control means 14 for generating information.
- the control means of the present embodiment is not limited to a force NC control device which is an NC control device for controlling electric discharge machining based on NC data, and can obtain the same effect by using a computer control device or the like.
- the electric discharge machining apparatus has a discharge power source 15 for applying a discharge voltage between the workpiece 1 and the electrode 5 in order to generate a discharge between them.
- the reference plane F is the upper surface of the bed 4 that is horizontally adjusted on the installation ground, and the XY plane on the processing is set parallel to the reference plane F.
- the width direction on the upper surface of the bed 4 is set to the X-axis direction, and the force is applied to the device.
- the depth direction on the upper surface of the bed 4 is set to the Y-axis direction, the front side of the worker toward the apparatus is set to be positive, and the depth side is set to be negative.
- the normal direction of the upper surface is set to the Z-axis direction, and the upper part of the worker toward the apparatus is set to be positive, and the lower part is set to be negative.
- the head 9 can move linearly in the Z-axis direction.
- the ram 10 is movably supported by the X-axis and the X-axis, respectively, by linear bearings.
- An electrode moving means 17 is constituted by the head 9 and the ram 10.
- a rotating shaft table 3 is provided on a support member (not shown) that stands on the bed 4.
- the ⁇ -axis table 3 rotates around the ⁇ -axis at a predetermined radius of curvature R.
- the C-axis table 2 is rotatably supported on the 3-axis table 3 with respect to the C-axis (see FIGS. 2_1 and 2_2).
- the C-axis table 2 and the ⁇ -axis table 3 constitute a supported material supporting means 16.
- the angle formed between the normal to the surface of the workpiece 1 and the X- X axis plane is such that the ⁇ axis table 3 is rotated to a desired angle. It is set by the following. Further, the electrode 5 is held by the electrode holder 6, and the displacement of the electrode 5 in the X-axis and ⁇ -axis directions is restricted by the electrode guide 7 at a position close to the workpiece 1. With such a structure, the X-axis and Y-axis positions of the electrode 5 can be accurately controlled even when the electrode 5 is a small-diameter electrode, for example, a small-diameter electrode having a diameter of 1 mm or less. can do.
- the electrode holder 6 is supported by the head 9, the electrode guide 7 is supported by the ram 10, and the head 9 is supported by the ram 10, which controls the X-axis and Y-axis positions of the ram 10. Accordingly, the positions of the electrode holder 6 and the electrode guide 7 in the X-axis and Y-axis directions can be controlled synchronously.
- the position of the electrode 5 in the Z-axis direction is controlled by controlling the position of the head 9 moving in the Z-axis direction while controlling the position of the electrode 5 in the X-axis and Y-axis directions. Can be done. That is, while controlling the position of the electrode guide 7 in the X-axis and Y-axis directions, the electrode 5 is advanced in the negative Z-axis direction along the electrode guide 7 to form a hole in the workpiece 1. You can do it.
- Diffuser holes are small holes widely used for cooling turbine blades.
- Fig. 3-1, Fig. 3-2 and Fig. 3-3 show this diff user hole It is a figure which shows the detail of.
- Figure 3-1 is a front view of the diff user hole
- Figure 3-2 is a cross-sectional view along the line AA in Figure 3-1
- Fig. 3-3 is a sectional view taken along the line BB of Fig. 3-1.
- the broken line and the dashed line in the figure represent the scanning trajectory of the electrode 5 at the time of electric discharge machining.
- the diffuser hole 20 is formed by inclining the thin plate portion of the material 1 to be worked.
- the diffuser hole 20 has a rectangular tapered hole 21 and a straight hole 22.
- Fig. 3-2 Cooling air flows from the bottom to the top (from the negative side of Z to the positive side of Z), and the flow is smoothly reduced as an enlarged flow in the rectangular tapered hole 21 to control the separation while suppressing flow separation. Smoothly cools the upper surface of the glue 1 Cools the upper surface of the roll 1 by diffusing air. This cooling method is widely used for cooling turbine blades.
- the straight hole 22 is an oblique prism and is surrounded by the regular surfaces 22a, 22b, 22c, and 22di.
- the opposing side surfaces 22a and 22c, together with the surface la, are each parallel to the Y axis and obliquely intersect the X axis.
- the angle at which the side surfaces 22a and 22c intersect with the surface la in the X-Z plane is ⁇ degrees.
- the surface la and the back surface of the material 1 are parallel.
- the side surfaces 22b and 22d are respectively parallel to the X axis and cross at right angles to the Y axis.
- the rectangular tapered hole 21 is a truncated quadrangular pyramid with the top removed, and is surrounded by the side surfaces 21a, 21b, 21c, and 21d.
- the side surface 21a and the surface la are respectively parallel to the Y axis and intersect the X axis.
- the angle at which the surface la intersects with the side surface 21c is defined as ⁇ (degree).
- the side surfaces 21b and 21d are parallel to the X axis and cross obliquely with the Y axis.
- the angle at which the surface la intersects with the side surface 21b is j3 (degrees).
- the NC control device 12 controls the position of the B-axis table 3 and the C-axis table 2 to move the workpiece 1 to the rectangular taper hole 21 of the diffuser hole having the target machining shape.
- Side 21 (s The same applies to the side surface 22a of the plate hole 22) so as to be parallel to the Z axis.
- the B-axis table 3 and the C-axis table 2 are fixed to the bed 4. That is, the workpiece is tilted and held so that one inner surface of the target working shape of one diffuser hole and the Z axis are parallel (positioning holding step). Thereafter, the process proceeds to a processing step.
- the NC control device 12 controls the positions of the head 9 and the ram 10 to move the electrode 5 and adjust the distance from the workpiece 1.
- the electric discharge machine 15 is driven to perform electric discharge machining.
- FIG. 5 is a diagram showing a scanning locus near the opening of the rectangular tapered hole portion 21 of the diff user hole.
- FIG. 6 is a diagram showing a scanning locus at the center of the rectangular tapered hole 21 of the differential user hole.
- FIG. 7 is a diagram showing a scanning trajectory over the entire rectangular tapered hole 21 of the diffuser hole.
- the NC control device 12 virtually divides the target machining shape into a plurality of planes orthogonal to the Z axis. Then, electric discharge machining is performed sequentially from the layer closest to the surface la of the material 1 to be processed.
- the dashed line in FIG. 5 shows the scanning trajectory. Starting from the starting point A in the upper right of FIG. 5 in the first stage, first, move in the negative direction of the X-axis to machine the upper right end of the hole opening (solid line) in FIG. Next, it moves in the negative direction of the Y-axis, returns in the positive direction of the X-axis, reaches the end point B, and ends the first-stage machining.
- the electrode 5 is carved by a predetermined amount in the negative direction of the Z-axis, and the process proceeds.
- the start point C of the next stage is the closest position to the end point B of the previous stage. That is, from the start point C, it proceeds in the negative direction of the X axis, then moves in the positive direction of the Y axis, and then returns to the positive direction of the X axis to reach the end point D.
- the second step is completed by moving from point C to point D. In this way, a predetermined amount is engraved in the negative direction of the Z-axis along the taper at the start point E closest to the end point D, and the third stage of processing is performed. Scanning from the start point E to the end point F completes the third-stage machining.
- the electrode 5 is engraved in the Z-axis direction by a predetermined amount on the workpiece 1, and then the electrode is moved to the target in the XY plane.
- the electrode 5 is moved along the contour of the processing shape, and then the electrode 5 is further engraved in the Z-axis direction by a predetermined amount.
- the electrode 5 is moved along the contour of the target machining shape in the XY plane, and the rectangular taper hole 21 is carved by repeating this operation. In this manner, the movement of the electrode 5 when the opening of the rectangular tapered hole 21 is adjusted to a locus that reciprocates in a U-shape, thereby omitting the idle running locus that is not processed.
- free running is performed by the radius length of the electrode 5 at both ends of the U-shape.
- the surface shape of the object 1 varies.
- the tapered opening shape can be reliably obtained without leaving any processing.
- a mouth-shaped scanning trajectory is indicated by a dashed-dotted line
- a U-shaped scanning trajectory is indicated by a broken line.
- the movement from the last point J to the point G is the force that causes free running when the dimensional accuracy of the surface shape of the workpiece 1 is high. By discharging the gas in the movement from J to the point G, the workpiece 1 in this section can be removed to secure the opening shape.
- FIG. 7 shows a state in which the electric discharge machining of the tapered hole shape is advanced by the scanning trajectory of the mouth shown in FIG.
- a four-step mouth-shaped scanning trajectory is processed in the negative direction of the Z axis.
- the inclined rectangular tapered hole 21 is discharged by the movement of the U-shaped electrodes in FIGS. 5 and 6 and the open-ended electrodes in FIGS. 6 and 7 described above. Can be. Since the electrodes are consumed as the electric discharge machining progresses, the electrodes are moved in the negative direction of the Z axis by the amount of the consumed electrodes. This moving amount may be a value corresponding to the moving distance of the electrode. In addition, this ratio may be set for each processing portion to correct the shape error.
- FIG. 8 shows a cross section of the cylindrical electrode 5 and a cross section of the rectangular tapered hole portion 21 of the differential user hole 20 in the process of being processed.
- the thickness of the cylindrical electrode 5 is t, and the electrode 5 is flat with the rectangular tapered hole 21.
- Let p be the length in the Z direction of the cylindrical surface (dashed-dotted line) when the line is worn out. Since the electrode 5 is parallel to the Z-axis, the angle of the slope of the rectangular tapered hole 21 with respect to the Z-axis is a-y as is clear from FIG. 3-2. Therefore, p is given by
- ⁇ is a discharge gap in the ⁇ direction
- ⁇ 1 is a value of 1 to 5 times ⁇ .
- Equation 2 is represented by ⁇
- Equation 4 Any real number satisfying 0 ⁇ k ⁇ 4. Substituting Equation 1 into Equation 3 gives: 6 [Equation 4]
- FIG. 9 shows a three-dimensional scanning trajectory of the straight hole portion 22.
- the straight hole 22 is formed by scanning in the order of the points K, L, M, N, and ⁇ . As the scanning progresses, the machining proceeds in the negative direction of the Z-axis and the spiral progresses, so the X and Y coordinates of point K and point O are the same.
- the Z coordinate of point ⁇ is the Z of point K Less than the coordinates.
- the trajectory when such scanning is advanced is shown in FIG. 10, and the straight portion is discharged along the trajectory.
- the diameter of the electrode 5 used for scanning is set to be the narrowest part of the diffuser hole.
- the electrode 5 having an electrode diameter as large as possible with respect to the width of the straight hole 22 in the X-axis direction is used.
- the electrode 5 can obtain a desired shape that does not move in the X-axis direction in the processing of the straight portion.
- Increasing the electrode diameter as much as possible means increasing the facing area between the electrode and the object to be discharged, thereby increasing the discharge area, and the so-called area effect widely known in the discharge field. As a result, the discharge becomes stable and the machining speed increases.
- the electrode diameter D may be selected such that
- the trajectory of each step is parallel to the XY plane, and the straight section is also adjusted as the trajectory that proceeds to the next step by moving in the negative direction of the Z axis. be able to.
- a radius is applied to the force portion.
- the scanning trajectories shown in Fig. 5 to Fig. 7 and Fig. 9 to Fig. 10 show the discharge point when the electric discharge machining is performed, and the extension line of the electric discharge machining point when the electric motor is running. In Fig. 5 to Fig. 7 and Fig. 9 to Fig. 10, the trajectory is shown with the radius omitted.
- the object to be dried is inclined to perform the discharge power generation by three-dimensional scanning, thereby having a side surface oblique to the surface of the object to be dried. Diffuser holes can be machined.
- control the gap between the electrode and the electrode to maintain stable discharge without including the B-axis and C-axis tables, and limit the control to only the X-axis, ⁇ -axis, and Z-axis.
- the amount of computation of the NC control device required for gap control can be reduced, and the NC control device can be configured at low cost.
- the free running distance can be shortened and the machining time can be shortened.
- the feed amount in the Z direction of the electrode should be set sufficiently large with respect to the thickness of the pipe-shaped electrode. Thus, the processing time can be reduced.
- the processing time can be shortened by using an electrode having a sufficiently large electrode diameter with respect to the cross-sectional shape of the diffuser hole.
- the rectangular tapered hole portion 21 of the diff user hole can be reliably processed.
- the electrode 5 is not intermittently moved in the Z-axis direction, so that the consumption shape of the electrode tip tends to be in a steady state, so that electrode consumption can be suppressed.
- the program can be simplified by giving only the Z-axis negative progression value per movement amount and the XY coordinates in NC data programming.
- FIG. 12 shows a rough discharge machining using a long-pulse low-peak waveform current for explaining a discharge control method according to the second embodiment of the present invention, and a short-pulse waveform current is used after the rough discharge power control.
- FIG. 6 is a perspective view showing a scanning trajectory at the time of finishing discharge control.
- the structure of the electric discharge machine is the same as that of the first embodiment.
- the NC control device 12 includes a rough electric discharge machine 41 and a finish electric discharge machine. 42.
- a solid line 51a shows an outline shape of an opening of a small hole in the rough electric discharge machining
- a broken line 51b shows an outline shape of a scanning trajectory in the rough electric discharge machining.
- the one-dot broken line 52 indicates the outer shape of the scanning trajectory in the finishing discharge pump. In each of the outer shapes 51a, 51b, and 52, the radius of the corner generated when a cylindrical electrode is used is omitted.
- finishing discharge power filter having a short pulse current waveform.
- the scanning trajectory of finishing EDM is offset from the scanning trajectory of rough EDM in the direction to widen the hole.
- a short noise waveform is used, so that the discharge trace on the workpiece surface where the heat transfer time is short is small and shallow. Also, the altered layer becomes thinner.
- FIG. 13 and FIG. 14 are XY cross sections of the narrow hole shape of FIG. 12, and schematically show the processed surface.
- FIG. 13 shows a cross section after the rough electric discharge machining.
- the surface of the workpiece 1 after the rough electric discharge machining has a thick altered layer 53 having a large surface roughness.
- the material strength of the heated material 1 is, for example, a heat-resistant alloy, which has a high high-temperature strength.
- the surface roughness increases. Further, since the blown-off amount is small, the deteriorated layer also becomes thick.
- the surface roughness becomes large, and the deteriorated layer becomes thick.
- the heat conduction time is prolonged, and the discharge trace that is thickened by the deteriorated layer becomes large and the surface roughness becomes large.
- the dashed line indicates the scanning trajectory 54 of the finish electric discharge machining performed after the rough electric discharge machining.
- FIG. 14 shows the result obtained by taking the scanning trajectory 54 of the finish electric discharge machining so as to include the thick altered layer 53.
- FIG. 14 shows a cross section after the finish electric discharge machining, and the deteriorated layer 53 having a small surface roughness is thinner than the rough electric discharge machining shown in FIG. Due to the use of short noise, the affected layer, which has a short heat conduction time, becomes thin. In addition, since the discharge marks are small, the surface roughness is small.
- the electric discharge per unit time is increased.
- electrode consumption can be suppressed by keeping the current value low.
- the electrode material is a metal containing copper such as brass, and the thermal conductivity is controlled by the workpiece.
- electrode wear can be suppressed while increasing the processing speed.
- FIG. 15-1, FIG. 15-2, and FIG. 15-3 are diagrams illustrating a straight prepared hole for preparing a prepared hole for explaining the electric discharge method according to the third embodiment of the present invention, as viewed from three directions.
- Fig. 15-1 is a front view of the straight pilot hole
- Fig. 15_2 is a cross section A_A of Fig. 15_1
- Fig. 15_3 is a cross section BB of 015-1.
- the electric discharge machining apparatus is configured to cut a straight pilot hole with the electric discharge machining apparatus of the first embodiment. Others are the same, and the description of the same parts is omitted.
- the straight pilot hole 55 includes two cylindrical holes.
- the cylindrical electrode 5 used for machining the straight pilot hole 55 moves in the Z-axis direction, and the center of the electrode draws a straight locus 56.
- the cylindrical electrode 5 is advanced in the negative direction of the Z-axis to form a cylindrical straight pilot hole 55.
- two holes are formed so as to be in contact with each other based on the relationship between the final processed shape and the diameter of the cylindrical electrode 5.
- FIG. 16-1, Fig. 16-2 and Fig. 16-3 show the processing when the differential user hole 20 is created by scanning the electrode 5 as the second step after the straight pilot hole 55 is processed.
- the trajectory is schematically shown.
- Figure 16-1 is a front view of the diff user hall.
- FIG. 16-2 is a sectional view taken along line AA of FIG. 16-1.
- FIG. 16-3 is a sectional view taken along the line BB of FIG. 16-1.
- the finish margin around the straight pilot hole 55 is machined by the three-dimensional scanning described in the first embodiment.
- the electrode consumption is set in accordance with the volume of the remaining portion excluding the straight pilot hole 55, and the electrode is offset in the negative Z-axis direction in consideration of the electrode consumption.
- the straight pilot hole can have a constant shape with respect to changes in processing conditions such as variations in the material and shape of the electrode and workpiece.
- processing conditions such as variations in the material and shape of the electrode and workpiece.
- the volume to be processed by scanning the electrode can be reduced, a change in the shape of the electrode in response to a change in the processing conditions can be suppressed.
- new materials and shapes can be processed with high accuracy.
- FIG. 17 is a view showing an automatic continuous calorie of a multi-hole in the discharge gasket method according to the fourth embodiment of the present invention. It is a flowchart explaining a procedure. This flowchart shows that the work 1 is mounted on the table, the electrode holder is mounted on the ATC device (automatic tool changer), the setup is completed, and the process is started immediately after the operator presses the processing start button to start processing. First, continuous hole drilling is performed, beginning with the insertion of the electrode into the electrode guide.
- ATC device automated tool changer
- step S 11 the hole number n is set to 0 in the NC control device 12.
- step S12 a command is issued from the NC control device 12, the head 9 and the ram 10 are driven, and the electrode 5 is automatically inserted into the electrode guide 7 while the electrode 5 is rotated by the rotating mechanism 18.
- step S13 the NC controller 12 adds 1 to the hole number n.
- step S14 the B-axis table 3 and the C-axis table 2 are driven to rotate so that the center axis of the hole is parallel to the Z-axis with respect to the hole shape of the hole number n.
- step S15 the W axis for positioning the ram 10 and the electrode guide 7 in the Z direction is driven to position the X, ⁇ , and Z positions of the electrode guide with respect to the hole of the hole number n.
- step S16 the head 9 and the ram 10 are positioned based on the hole shape data stored in the NC data unit 13, and a desired hole shape is subjected to electric discharge machining.
- the hole shape data may be created separately from the NC main program as a subprogram by CAM or manually by an operator.
- the NC main program includes all steps except step S16 in the flowchart of FIG.
- the machining program can be greatly simplified by using the common shape data for a plurality of hole numbers.
- step S17 it is determined whether or not to end the processing, and if it is, the process proceeds to step S18 to end the processing.
- step S19 it is determined whether or not the electrode protrusion length is sufficient for the next processing. If it is sufficient, the process returns to step S13 and proceeds to the processing of the next hole number.
- step S20 it is determined whether or not the electrode length of the electrode holder 6 is sufficient for the next processing. If it is sufficient, the process proceeds to step S21 to perform an operation of automatically extracting the electrode. If the electrode length is not enough, proceed to step S22, operate the ATC device, and replace the electrode 5 together with the electrode holder 6.
- step S16 is generated so that a desired hole shape can be obtained with a margin, as described in the first embodiment, even if the surface shape of the workpiece 1 slightly changes.
- the same scanning trajectory can be used for the holes.
- the NC program can be greatly simplified, the NC program creation time can be reduced, and program errors can be reduced. it can.
- FIG. 18 is a graph illustrating a relationship between an electrode protrusion length and a processing time for explaining a discharge control method according to a fifth embodiment of the present invention.
- the electrode protrusion length is a length from the lower end surface of the electrode holder 6 to the tip of the electrode 5.
- the reason why the calorie time becomes longer near the length of 90 mm is that the electrode rotation speed and the lateral deflection vibration of the electrode resonate, and this vibration affects the discharge and the kaget speed decreases. Let's express things.
- the electrode protruding length is controlled by the NC control device 12 by the end face positioning operation of pressing the electrode against the workpiece and detecting the end face of the workpiece while performing contact detection while regarding the conduction between the electrodes as contact.
- the number of rotations of the electrode 5 is adjusted according to the protruding length. This adjustment timing is immediately after the end face positioning operation.
- the electrode rotation speed is 3000 r / min to avoid resonance.
- the outer diameter of the electrode is dl
- A is the cross-sectional area of the electrode (mm2)
- E Young's modulus (kgf / mm3)
- P is the density (kg / mm3).
- FIG. 19 shows a procedure for processing while setting the number of rotations so as to avoid such resonance.
- step S1 the electrode length, the inner diameter of the electrode, the outer diameter of the electrode, and the material are input to the electrode control means 19 of the NC control device 12.
- step S2 the material, the Young's modulus, and the material previously input to the electrode control means 19 of the NC control device 12 are determined from the electrode length, the electrode inner diameter, the electrode outer diameter, and the material input in step S1.
- Using a density table then, values are set for the length L, the Young's modulus E, and the density p of the electrode lateral vibration part, and the natural frequency ⁇ is calculated based on Equation 6.
- step S3 the electrode control is performed using the electrode rotation speed ⁇ (r / min) that is not included in the electrode rotation speed ⁇ corresponding to the natural frequency ⁇ within ⁇ 15% of the natural frequency ⁇ .
- Means 19 rotates the electrodes. That is, ⁇ is ⁇ ⁇ 0.85X60X ⁇ (2 ⁇ ) or ⁇ > 1.15X60X ⁇ / (2 ⁇ ).
- step S4 the hole number ⁇ ( ⁇ is a positive integer. If the number of holes to be machined is ⁇ , 1 ⁇ ) is set to 1, and the ⁇ th hole is machined from step S5.
- step S6 the machining time of the ⁇ -th hole in step S5 is multiplied by a preset wear correction coefficient to calculate an electrode wear length, and this is subtracted from the electrode length L to obtain an equation 6
- the natural frequency ⁇ is calculated again based on.
- step S7 the electrode 5 is rotated at an electrode rotation speed ⁇ (rZmin) that is not included in the electrode rotation speed ⁇ corresponding to the natural frequency ⁇ within ⁇ 15% of the recalculated natural frequency ⁇ .
- the resonance decreases in principle when the rotation frequency is as far away from the natural frequency as possible. However, practically, resonance can be sufficiently suppressed by using the following rotation speed range. That is, ⁇ is 0.85X60X ⁇ / (2 ⁇ ) or ⁇ > 1.15X60X ⁇ / (2 ⁇ ).
- step S8 the hole number n is incremented by 1, and it is determined in step S9 whether or not to end the processing. If not, return to step S5 to machine the nth hole.
- the electrode is automatically extracted as described in Embodiment 4 as appropriate, the natural frequency is calculated in consideration of the electrode extraction length, and the electrode is set so as to avoid resonance. It is good to set the number of rotations.
- FIG. 20-1, FIG. 20-2, and FIG. 20-3 are cross-sectional views showing various examples of the positional relationship between the tapered hole and the electrode for explaining the electric discharge machining method according to the sixth embodiment of the present invention.
- the differential user hole 20 as a deformed thin hole having a rectangular tapered hole portion 21 and a straight hole portion 22 is a force to be machined.
- the tapered hole 71 inclined with respect to the surface of the workpiece 1 is to be subjected to the force control.
- the tapered hole 71 has a tapered spread angle ⁇ as shown in FIG. 20-1.
- the tapered hole 71 of the present embodiment since there is no straight hole, if the Z-axis is parallel to an arbitrary angle within the range of the spread angle ⁇ , the tapered hole 71 is removed. be able to.
- the workpiece 1 may be held inclined so that the inner surface 71c on one side is parallel to the Z-axis, or as shown in FIG. 20-3.
- the object 1 may be tilted and held so that the inner surface 71a on the other side is parallel to the Z-axis, or may be held in the middle between the two as shown in Figure 20-2. I'm sorry.
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- Chemical Kinetics & Catalysis (AREA)
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- Electrical Discharge Machining, Electrochemical Machining, And Combined Machining (AREA)
Abstract
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JP2003299655A JP2006346752A (ja) | 2003-08-25 | 2003-08-25 | 放電加工方法 |
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Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP3085483A1 (en) * | 2015-04-24 | 2016-10-26 | General Electric Company | A method for profile machining |
CN106068168A (zh) * | 2014-03-06 | 2016-11-02 | 株式会社牧野铣床制作所 | 加工程序的生成方法、路径生成装置以及放电加工机 |
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JP2011025345A (ja) * | 2009-07-24 | 2011-02-10 | Elenix Inc | 細穴放電加工方法および装置 |
US9676046B2 (en) * | 2012-07-31 | 2017-06-13 | Makino Milling Machine Co., Ltd. | Electrical discharge machining method |
KR101952544B1 (ko) * | 2018-09-07 | 2019-02-26 | 국방과학연구소 | 전극봉을 이용한 확산형 구멍 형성 방법 |
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JPS5754026A (en) * | 1980-09-10 | 1982-03-31 | Mitsubishi Electric Corp | Conductivity processing method |
JPS57173423A (en) * | 1981-04-17 | 1982-10-25 | Inoue Japax Res Inc | Electric discharge machining equipment |
JPH08132263A (ja) * | 1994-11-08 | 1996-05-28 | Mitsubishi Heavy Ind Ltd | 異形穴レーザー加工方法 |
JPH08300223A (ja) * | 1995-05-10 | 1996-11-19 | Mitsubishi Electric Corp | 放電加工装置 |
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JP2003129971A (ja) * | 2001-10-23 | 2003-05-08 | Mitsubishi Electric Corp | 圧縮機、圧縮機の加工方法 |
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JPS5754026A (en) * | 1980-09-10 | 1982-03-31 | Mitsubishi Electric Corp | Conductivity processing method |
JPS57173423A (en) * | 1981-04-17 | 1982-10-25 | Inoue Japax Res Inc | Electric discharge machining equipment |
JPH08132263A (ja) * | 1994-11-08 | 1996-05-28 | Mitsubishi Heavy Ind Ltd | 異形穴レーザー加工方法 |
JPH08300223A (ja) * | 1995-05-10 | 1996-11-19 | Mitsubishi Electric Corp | 放電加工装置 |
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CN106068168A (zh) * | 2014-03-06 | 2016-11-02 | 株式会社牧野铣床制作所 | 加工程序的生成方法、路径生成装置以及放电加工机 |
US10556281B2 (en) | 2014-03-06 | 2020-02-11 | Makino Milling Machine Co., Ltd. | Processing program-generating method, path-generating device and electrical discharge machine |
EP3085483A1 (en) * | 2015-04-24 | 2016-10-26 | General Electric Company | A method for profile machining |
US20160311044A1 (en) * | 2015-04-24 | 2016-10-27 | General Electric Company | Method for profile machining |
JP2016203370A (ja) * | 2015-04-24 | 2016-12-08 | ゼネラル・エレクトリック・カンパニイ | プロファイル加工方法 |
US10974336B2 (en) | 2015-04-24 | 2021-04-13 | General Electric Company | Method for profile machining |
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