Electrical discharge machining system with integral flushing

Abstract

The present application provides an electrical discharge machining system (100) for drilling a hole (96) in a workpiece (25) using a flushing fluid (91). The electrical discharge machining system (100) may include an electrode (110) disposed within an electrode guide (120), and an integrated external flushing system (140). The integrated external flushing system (140) may include a guide cap (125) and a concentric flushing channel (150) defined between the guide cap (125) and the electrode guide (120) to enable the flushing fluid (91) to remain attached to the electrode guide (120).

Description

[Technical Field]

[0001] FIELD OF THE INVENTION This application and the resulting patent relate generally to electrical discharge machining systems, and more particularly to electrical discharge machining systems having integrated electrode flushing to reduce overall ejection time. [Background technology]

[0002] Electrical discharge machining (EDM) is a manufacturing process that uses electrical discharges, or sparks, to create features in a workpiece. A tool electrode is placed in close proximity to the workpiece, and a voltage is applied between the tool electrode and the workpiece. When the strength of the electric field between the tool electrode and the workpiece exceeds the resistance of the dielectric medium between them, current flows from the electrode to the workpiece, or vice versa, removing some material from both the electrode and the workpiece.

[0003] EDM drilling is a reliable process for forming cooling holes and fuel injection holes in turbine components (e.g., airfoils, etc.). As such, EDM drilling is widely used in the turbine industry. However, EDM drilling can be relatively slow, especially if debris accumulates within the partially drilled hole. Specifically, flushing water can flow through the center of the EDM electrode during drilling. However, once the electrode erupts, flushing water through the center of the electrode may not be able to carry away the EDM chips, i.e., debris, outside the electrode quickly and efficiently enough. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Chinese Utility Model No. 210620234 Summary of the Invention

[0005] This application and resultant patent provide an electrical discharge machining system for drilling holes in a workpiece using a flushing fluid. The electrical discharge machining system may include an electrode disposed within an electrode guide and an integrated external flushing system. The integrated external flushing system may include a guide cap and a concentric flushing channel defined between the guide cap and the electrode guide to allow flushing fluid to remain attached to the electrode guide.

[0006] The present invention and resultant patent further provide a method for reducing debris around an electrode while drilling a hole in a workpiece with an electrical discharge machining system. The method may include drilling a hole with the electrode, flowing a flushing fluid through an internal flushing chamber in the electrode, flowing the flushing fluid through an integrated external flushing system around the electrode guide, and continuing to flow the flushing fluid through the integrated external flushing system even when the electrode protrudes from the workpiece. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 is a schematic diagram of an exemplary electrical discharge machining system. [Figure 2] FIG. 2 is a further schematic diagram of the electrical discharge machining system of FIG. 1. [Figure 3] FIG. 2 is a schematic diagram of the electrical discharge machining system of FIG. 1 in use. [Figure 4] FIG. 2 is a further schematic diagram of the electrical discharge machining system of FIG. 1 in use. [Figure 5] FIG. 1 is a schematic diagram of an integrated exterior flushing system that may be described herein. [Figure 6] FIG. 6 is a schematic diagram of the integrated external flushing system of FIG. 5 in use. [Figure 7] FIG. 6 is a further schematic diagram of the integrated external flushing system of FIG. 5 in use. [Figure 8] FIG. 6 is a further schematic diagram of the integrated external flushing system of FIG. 5 in use. DETAILED DESCRIPTION OF THE INVENTION

[0008] Referring now to the drawings, wherein like numerals indicate like elements throughout the several views, FIGS. 1 and 2 are schematic diagrams of a portion of an electrical discharge machining (EDM) system 10. As shown, the EDM system 10 may include a guide structure 15 and one or more electrode devices 20 disposed at least partially within the guide structure 15. The electrode devices 20 provide an electrical discharge to a workpiece 25, e.g., a turbine component such as a gas turbine airfoil. (Shown in FIGS. 3 and 4.) Each of the electrode devices 20 includes an electrode 30 for positioning about (e.g., in contact with or nominally separated from) the workpiece 25. An electrode guide 35 may be coupled to the electrode 30 to hold the electrode 30 in proximity to the workpiece 25.

[0009] The electrode apparatus 20 may be disposed within the plain bearing 40 and back plate 45. The electrode apparatus 20 may be driven via a drive device 50 and a piston 55. The electrode apparatus 20 may further include a rotary tube electrode apparatus 60. The rotary tube electrode apparatus 60 may be coupled to the piston 55. The rotary tube electrode apparatus 60 may further include an air rotation driver 65 including an air motor 70 (having a compressed air inlet 72 and an outlet 74), a water inlet 75 (having an adjacent seal 77) upstream of the air motor 70, and a rotor 80 (the rotor 80 is supported on a bearing 85) coupled to the air motor 70. In this configuration, the rotary tube electrode apparatus 60 can rotate the electrode 30 while the piston 55 drives the electrode 30 toward and away from the workpiece 25. Therefore, the rotary tube electrode apparatus 60 shown herein may be useful for forming holes in a workpiece 25 in a space requiring minimal clearance.

[0010] The EDM system 140 may further include a fluid source 90 for flushing the electrode 30. As an example, side flushing is shown in FIG. 3, where flushing fluid 91 is introduced onto the exterior surface of the electrode 30 from a side region via a nozzle 92. FIG. 4 shows flushing fluid 91 introduced through the body of the electrode 30 via an internal flushing chamber 94. As mentioned above, this method can be slow during ejection because the flushing fluid 91 cannot efficiently carry away EDM debris.

[0011] FIG. 5 illustrates a portion of an EDM machining system 100 as may be described herein. The EDM machining system 100 may include an electrode 110 disposed within an electrode guide 120. The electrode 110 may be of conventional design and may have any suitable size, shape, and configuration herein. The electrode guide 120 may be generally tubular in shape having any suitable size, shape, or configuration herein. The electrode guide 120 may be supported at one end by a guide arm 115 and at the other end by a guide cap 125. Other types of supports may be used herein. The electrode 110 may include an internal flushing chamber 130 extending therethrough. The internal flushing chamber 130 may be in communication with the fluid source 90 or another source of flushing liquid, such as water. The flushing fluid 91 flows into holes 96 formed in the electrode 110 as it advances through the workpiece 25. Other components and configurations may be used herein.

[0012] The EDM machining system 100 may also include an integrated external flushing system 140. The integrated external flushing system 140 may include a concentric fluid channel 150. The concentric fluid channel 150 may be defined at one end by the electrode guide 120 and the guide arm 115 and at the other end by the guide cap 125. The concentric fluid channel 150 may be in communication with the fluid source 90 or another source of flushing fluid. The concentric fluid channel 150 may have any suitable size, shape, or configuration. Specifically, the flushing fluid 91 may flow along the length of the electrode guide 120, between the electrode guide 120 and the guide arm 115, and between the electrode guide 120 and the guide cap 125. Other components and configurations may be used herein.

[0013] 6-8 show the integrated external flushing system 140 in use. As shown in FIG. 6, as the electrode 110 begins to drill into the workpiece 25, flushing fluid 91 from the fluid source 90 spreads through the internal flushing chamber 130, carrying away debris around the electrode 110. Similarly, the flushing fluid 91 from the integrated external flushing system 140 helps carry away debris from the electrode 110 and the electrode guide 120. As shown in FIGS. 7 and 8, even as the electrode 110 begins to protrude from the workpiece 25, the flushing fluid 91 from the integrated external flushing system 140 continues to carry away debris from the electrode 110 and the electrode guide 120.

[0014] Thus, the use of the integrated external flushing system 140 allows the flushing fluid 91 to remain attached to the electrode guide 120 and within the bore 96 while the electrode 110 advances into the workpiece 25. Specifically, the concentric fluid channel 150 allows the flushing fluid 91 to flow along the electrode guide 120 and into the bore 96. The integrated external flushing system 140 should therefore reduce overall cycle time when ejecting from the bore 96 at shallow or other angles. Specifically, herein, an approximately 50% reduction in dwell time after the initial ejection may be achieved. Additionally, overall wear on the electrode 110 may be reduced. The integrated external flushing system 140 therefore provides effective and repeatable flushing of debris while allowing the overall EDM system 100 to accommodate electrodes 110 of different sizes therein.

[0015] It should be apparent that the foregoing relates only to certain embodiments of this application and the resulting patent. Numerous changes and modifications may be made herein by those skilled in the art without departing from the general spirit and scope of the invention as defined by the following claims and their equivalents.

[0016] Further aspects of the invention are provided by the subject matter of the following clauses. [Embodiment 1] 1. An electrical discharge machining system for drilling holes in a workpiece using a flushing fluid, comprising: an electrode disposed within an electrode guide; and an integrated external flushing system comprising a guide cap and a concentric flushing channel defined between the guide cap and the electrode guide such that flushing fluid can remain attached to the electrode guide. [Embodiment 2] 10. The electrical discharge machining system of any one of the preceding clauses, wherein the integrated external flushing system comprises a flushing fluid source in communication with the concentric flushing channel. [Embodiment 3] 10. The electrical discharge machining system of any one of the preceding clauses, wherein the electrode is provided with an internal flushing system. [Embodiment 4] 10. The electrical discharge machining system of any one of the preceding clauses, wherein the internal flushing system is in communication with a source of flushing fluid. [Embodiment 5] 10. The electrical discharge machining system of any one of the preceding clauses, wherein the electrode guide accommodates a plurality of different sized electrodes. [Embodiment 6] 10. The electrical discharge machining system of any one of the preceding clauses, wherein the integrated external flushing system comprises a guide arm supporting the electrode guide. [Embodiment 7] 10. The electrical discharge machining system of any one of the preceding clauses, wherein the concentric flushing channel extends partially between the electrode guide and the electrode arm. [Embodiment 8] 10. The electrical discharge machining system of any one of the preceding clauses, further comprising a piston in communication with the electrode. [Embodiment 9] 10. The electrical discharge machining system of any one of the preceding clauses, further comprising a rotating tube system in communication with the piston. [Embodiment 10] 1. A method for reducing debris around an electrode while drilling a hole in a workpiece with an electrical discharge machining system, the method comprising: drilling a hole with the electrode; flowing flushing fluid through an internal flushing chamber in the electrode; flowing flushing fluid through an integrated external flushing system around an electrode guide; and continuing to flow flushing fluid through the integrated external flushing system even when the electrode protrudes from the workpiece. [Explanation of symbols]

[0017] 10 EDM systems 15 Guide structure 20 Electrode device 25 workpieces 30 electrodes 35 Electrode Guide 40 Bearings 45 backplate 50 Drive unit 55 Piston 60 Rotating tube electrode device 65 Air Rotation Driver 70 Air Motor 72 Compressed air inlet 74 Exit 75 Water inlet 77 Adjacent Seal 80 rotors 85 bearings 90 Fluid source 91 Flushing Fluid 92 nozzles 94 Internal flushing chamber 96 holes 100 EDM processing system, EDM system 110 electrodes 115 Guide Arm 120 Electrode Guide 125 guide cap 130 Internal flushing chamber 140 EDM system with integrated external flushing system 150 concentric fluid channels

Claims

1. 1. An electrical discharge machining system (100) for drilling holes (96) in a workpiece (25) using a flushing fluid (91), comprising: An electrode (110), an electrode (110) disposed within an electrode guide (120); An integrated exterior flushing system (140), comprising: an integrated external flushing system (140) comprising a guide cap (125) and a concentric flushing channel (150) defined between the guide cap (125) and the electrode guide (120) so that a flushing fluid (91) can remain attached to the electrode guide (120); An electrical discharge machining system (100) comprising:

2. The electrical discharge machining system (100) of claim 1, wherein the integrated external flushing system (140) comprises a flushing fluid source (90) in communication with the concentric flushing channel (150).

3. The electrical discharge machining system (100) of claim 2, wherein the electrode (110) comprises an internal flushing system (130).

4. The electrical discharge machining system (100) of claim 3, wherein the internal flushing system (130) is in communication with the flushing fluid source (90).

5. The electrical discharge machining system (100) of claim 1, wherein the electrode guide (120) accommodates a plurality of different sized electrodes (110).

6. The electrical discharge machining system (100) of claim 1, wherein the integrated external flushing system (140) comprises a guide arm (115) supporting the electrode guide (120).

7. The electrical discharge machining system (100) of claim 6, wherein the concentric flushing channel (150) extends partially between the electrode guide (120) and the guide arm (115).

8. The electrical discharge machining system (100) of claim 1, further comprising a piston (55) in communication with the electrode (110).

9. The electrical discharge machining system (100) of claim 8, further comprising a rotating pipe system (60) in communication with the piston (55).

10. 1. A method for reducing debris around an electrode (110) while drilling a hole (96) in a workpiece (25) using an electrical discharge machining system (100), comprising: drilling said holes (96) with said electrode (110); flowing a flushing fluid (91) through an internal flushing chamber (130) within said electrode (110); flowing a flushing fluid (91) through an integrated external flushing system (140) around said electrode guide (120); continuing to flow flushing fluid (91) through the integrated external flushing system (140) even when the electrode (110) protrudes from the workpiece (25); A method comprising:

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