US3793169A - Small hole ecm drilling with controlled current - Google Patents

Small hole ecm drilling with controlled current Download PDF

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Publication number
US3793169A
US3793169A US00216784A US3793169DA US3793169A US 3793169 A US3793169 A US 3793169A US 00216784 A US00216784 A US 00216784A US 3793169D A US3793169D A US 3793169DA US 3793169 A US3793169 A US 3793169A
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United States
Prior art keywords
current
electrolyte
drilling
depth
ecm
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Expired - Lifetime
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US00216784A
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English (en)
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F Joslin
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RTX Corp
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United Aircraft Corp
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Publication date
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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
    • B23H9/00—Machining specially adapted for treating particular metal objects or for obtaining special effects or results on metal objects
    • B23H9/14—Making holes
    • 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
    • B23H3/00—Electrochemical machining, i.e. removing metal by passing current between an electrode and a workpiece in the presence of an electrolyte
    • B23H3/02—Electric circuits specially adapted therefor, e.g. power supply, control, preventing short circuits
    • 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
    • B23H2200/00—Specific machining processes or workpieces
    • B23H2200/20—Specific machining processes or workpieces for making conical bores

Definitions

  • This invention relates to electrochemical machining, (ECM), and more particularly to improved ECM drilling of small holes.
  • a thin hollow cathode conducts the electrolyte to the work area through its central bore, and the effluent electrolyte flows away from the work area in the annular space created between the surface of the hole being drilled and the hollow cathode.
  • Electrical power equal to the product of the voltage across the gap times the current through the gap, accomplishes the useful work of metal removal and also creates heat in the work area, which warms the electrolyte.
  • the effluent electrolyte exiting from the drilled hole warms the incoming electrolyte through the walls of the hollow-cathode, in a heat exchange type of action.
  • a constant voltage is employed acrossthe gap.
  • an increase in current means an increase in the power generated in the gap, which power is taken up in the form of heat within the electrolyte, causing a further increase in the temperature. If the temperature becomes sufficiently high, the electrolyte will boil, causing vapor pockets in the gap; the vapor pockets insulate the anode from the cathode and thus preclude the electrochemical reaction from occurring; and, as the hollow cathode continues to advance, without erosion of the workpiece, the gap becomes smaller. If not corrected, this process may culminate in an unintentional contact between the cathode tip and the workpiece, which is commonly referred to as a spark-out.
  • the object of the present invention is to provide improved ECM drilling of small holes.
  • holes less than three hundredths of an inch in diameter and with a ratio of depth to diameter in excess of ten are drilled utilizing an electrochemical machining process in which the current is completely controlled.
  • drilling of substantially uniform straight holes is achieved employing a constant current in an ECM process.
  • drilling of contoured holes is accomplished by programming the current to feed rate ratio as a function of hole depth.
  • the present invention provides an order of magnitude increase in the rate at which small holes can be drilled using ECM processes.
  • the invention also permits the drilling of holes having desired contours, which are not otherwise readily obtainable.
  • the invention provides a very practical method of producing small holes in ordinary metals as well as super alloys.
  • FIG. 1 is a simplified schematic illustration of electrochemical machining apparatus which may be employed in the practice of the present invention
  • FIGS. 2, 4 and 6 are sectioned, side elevations of contoured holes; and v I FIGS. 3, 5 and 7 are current versus depth plots relating respectively to the contours of FIGS. 2, 4 and 6.
  • the feed mechanism 26 includes a ram 28 on which the collet 24 or other attaching means is suitably disposed.
  • the ram 28 may be journaled in a precision ball guide assembly comprising a plurality of balls (such as the balls 30) confined by a suitable plate (such as the plate 32). In fact, the entire surface of the ram 28 may preferably be guided by additional balls and plates (not shown).
  • the ram 28 may be advanced by a rack 34 and pinion 36 driven by a shaft 38 connected to a synchronous motor 40. Alternatively a precision ground ball screw or other suitable precise feed mechanism may be utilized, as is known in the art.
  • a controlled current DC source 42 is connected by a suitable lead 44 to the workpiece 10, and by a suitable lead 46 to the collet 24, thereby to impress a voltage between the hollow cathode 14 and the workpiece 10.
  • the electrolyte under a suitable pressure is driven through the hollow cathode 14 and out the end thereof in the vicinity of the gap formed between the end of the hollow cathode 14 and the workpiece metal in an area having a diameter slightly larger than the diameter of the hollow cathode 14 is eroded by electrochemical action, the metal forming a metallic hydroxide sludge which is flushed out of the hole as the effluent electrolyte passes upwardly in an annular passage formed between the surface of the hole '12 andthe hollow cathode 14.
  • the effluent electrolyte is collected in a suitable sump (not shown), as is known in the art.
  • substantially uniform deep holes are drilled at a relatively high feed rate.
  • a beryllium copper hollow cathode 14 having a 5 mil ID and a ten mil OD covered with a third of a mil parylene C insulation, used in drilling a high temperature nickel base alloy.
  • An electrolyte consisting of a saline solution (two pounds per galdrilled. The initial volta e was approximately ten volts and the voltage decaye toabout 6% volts as the drilling proceeded.
  • a hole was drilled at a rate of 0.3 inches per minute utilizing 400 rnilliamps constant current.
  • the depth sensor 48 may comprise a variable resistance having a wiper arm at tached to the ram 28, or any other suitable position sensor capable of response to the position of the ram 28, the collet 24, or the hollow cathode 14.
  • a variable resistance or voltage derived therefrom may be utilized so as to adjust the current setting of the control current DC source 42 as a function of depth.
  • the controlled current DC source 42 may be programmed to provide current (I) as a linear or nonlinear function 'of depth (D) so as to provide any desired hole contour as illustrated in FIGS. 2-7.
  • I current
  • D nonlinear function 'of depth
  • a jug-like shape is achieved as seen in FIG. 2 by first decreasing the current and then increasing it as illustrated in FIG. 3.
  • a wasp-waist configuration as seen in FIG. 4 is provided by a concave upward current curve as shown in FIG. 5.
  • a hole with an increasing diameter (suitable for use with cast or deformable rivets) as seen in FIG. 6, may be achieved by providing an increase in current with depth as illustrated in FIG. 7.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Electrical Discharge Machining, Electrochemical Machining, And Combined Machining (AREA)
US00216784A 1972-01-10 1972-01-10 Small hole ecm drilling with controlled current Expired - Lifetime US3793169A (en)

Applications Claiming Priority (1)

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US21678472A 1972-01-10 1972-01-10

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US3793169A true US3793169A (en) 1974-02-19

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US00216784A Expired - Lifetime US3793169A (en) 1972-01-10 1972-01-10 Small hole ecm drilling with controlled current

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US (1) US3793169A (enrdf_load_stackoverflow)
JP (1) JPS4880441A (enrdf_load_stackoverflow)
DE (1) DE2259419A1 (enrdf_load_stackoverflow)
FR (1) FR2167552A5 (enrdf_load_stackoverflow)

Cited By (14)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4687563A (en) * 1985-04-01 1987-08-18 Corning Glass Works Electrochemical machine apparatus with drill-depth and rate monitor
US4767903A (en) * 1984-12-31 1988-08-30 Ag Fur Industrielle Elektronik Agie Process and apparatus for determining the electroerosive completion of a starting hole
US4806216A (en) * 1988-01-21 1989-02-21 The United States Of America As Represented By The United States Department Of Energy Electrochemical polishing of notches
US5306401A (en) * 1993-03-15 1994-04-26 Fierkens Richard H J Method for drilling cooling holes in turbine blades
US5320721A (en) * 1993-01-19 1994-06-14 Corning Incorporated Shaped-tube electrolytic polishing process
US5322599A (en) * 1993-01-19 1994-06-21 Corning Incorporated Shaped-tube electrolytic machining process
US5685971A (en) * 1991-09-30 1997-11-11 General Electric Company Apparatus and method for forming a variable diameter hole in a conductive workpiece
EP0858855A1 (en) * 1997-02-06 1998-08-19 Corning Incorporated Method for machining extrusion dies
WO2001012372A1 (en) * 1999-08-16 2001-02-22 General Electric Company Method and tool for electrochemical machining
DE102010051871A1 (de) 2010-11-22 2012-05-24 Märkisches Werk GmbH Verfahren zur Herstellung von Ventilen für den Gasaustausch und nach einem derartigen Verfahren hergestellte Ventile
CN104511669B (zh) * 2013-09-29 2017-01-25 浙江工业大学 大长径比盘状阵列群电极的电化学加工方法
CN109070253A (zh) * 2015-10-23 2018-12-21 康明斯公司 用于产生可变喷射孔几何形状的放电加工方法
WO2021086455A3 (en) * 2019-07-05 2021-06-10 Voxel Innovations, Inc. Methods and apparatuses of oscillatory pulsed electrochemical machining
CN116551089A (zh) * 2023-05-05 2023-08-08 南京航空航天大学 一种恒电流管电极电解加工深小孔的装置

Families Citing this family (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4393292A (en) * 1979-07-17 1983-07-12 Inoue-Japax Research Incorporated Method of and apparatus for electrical discharge machining a small and deep hole into or through a workpiece
DE3879372T2 (de) * 1987-10-30 1993-06-24 Shizuoka Seiki Co Ltd Elektrolytisches fertigstellungsverfahren.
JP3080563B2 (ja) * 1995-08-21 2000-08-28 日本碍子株式会社 ハニカム構造体押出用ダイスの製造方法
DE10360080A1 (de) * 2003-12-20 2005-07-21 Robert Bosch Gmbh Verfahren und Vorrichtung zum Abtragen von metallischem Material eines Werkstücks
DE102011077198A1 (de) * 2011-06-08 2012-12-13 Mahle International Gmbh Verfahren zum Herstellen eines metallischen Hohlventils mit verbesserter Kühlung
DE102012110016A1 (de) * 2012-10-19 2014-04-24 Bernhard Wietrzynski Verfahren und Vorrichtung zum Herstellen einer Vertiefung mit Hinterschneidung

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3058895A (en) * 1958-11-10 1962-10-16 Anocut Eng Co Electrolytic shaping
US3389066A (en) * 1964-06-03 1968-06-18 Kyowa Hakko Kogyo Kk Method for electrolytically polishing iron and iron alloys
US3630877A (en) * 1967-09-18 1971-12-28 Mitsubishi Electric Corp Electrolytically machining apparatus

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3058895A (en) * 1958-11-10 1962-10-16 Anocut Eng Co Electrolytic shaping
US3389066A (en) * 1964-06-03 1968-06-18 Kyowa Hakko Kogyo Kk Method for electrolytically polishing iron and iron alloys
US3630877A (en) * 1967-09-18 1971-12-28 Mitsubishi Electric Corp Electrolytically machining apparatus

Non-Patent Citations (2)

* Cited by examiner, † Cited by third party
Title
De Barr et al. Electrochemical Machining, 1968 Amer. Elsenier Pub. Co., NY, NY, pages 45 47, 70 72, 80 82 and 191 192. *
Uhlir, Jr., The Review of Scientific Instruments Vol. 26, No. 10 October 1955 pp. 965 968. *

Cited By (19)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4767903A (en) * 1984-12-31 1988-08-30 Ag Fur Industrielle Elektronik Agie Process and apparatus for determining the electroerosive completion of a starting hole
US4687563A (en) * 1985-04-01 1987-08-18 Corning Glass Works Electrochemical machine apparatus with drill-depth and rate monitor
US4806216A (en) * 1988-01-21 1989-02-21 The United States Of America As Represented By The United States Department Of Energy Electrochemical polishing of notches
US5685971A (en) * 1991-09-30 1997-11-11 General Electric Company Apparatus and method for forming a variable diameter hole in a conductive workpiece
US5320721A (en) * 1993-01-19 1994-06-14 Corning Incorporated Shaped-tube electrolytic polishing process
US5322599A (en) * 1993-01-19 1994-06-21 Corning Incorporated Shaped-tube electrolytic machining process
US5306401A (en) * 1993-03-15 1994-04-26 Fierkens Richard H J Method for drilling cooling holes in turbine blades
KR19980071110A (ko) * 1997-02-06 1998-10-26 알프레드 엘, 미첼슨 압출 금형 가공 방법
EP0858855A1 (en) * 1997-02-06 1998-08-19 Corning Incorporated Method for machining extrusion dies
US5997720A (en) * 1997-02-06 1999-12-07 Corning Incorporated Method for machining extrusion dies
WO2001012372A1 (en) * 1999-08-16 2001-02-22 General Electric Company Method and tool for electrochemical machining
US6290461B1 (en) 1999-08-16 2001-09-18 General Electric Company Method and tool for electrochemical machining
DE102010051871A1 (de) 2010-11-22 2012-05-24 Märkisches Werk GmbH Verfahren zur Herstellung von Ventilen für den Gasaustausch und nach einem derartigen Verfahren hergestellte Ventile
CN104511669B (zh) * 2013-09-29 2017-01-25 浙江工业大学 大长径比盘状阵列群电极的电化学加工方法
CN109070253A (zh) * 2015-10-23 2018-12-21 康明斯公司 用于产生可变喷射孔几何形状的放电加工方法
US11602798B2 (en) * 2015-10-23 2023-03-14 Cummins Inc. Electrical discharge machining method for generating variable spray-hole geometry
US12194558B2 (en) 2015-10-23 2025-01-14 Cummins Inc. Electrical discharge machining method for generating variable spray-hole geometry
WO2021086455A3 (en) * 2019-07-05 2021-06-10 Voxel Innovations, Inc. Methods and apparatuses of oscillatory pulsed electrochemical machining
CN116551089A (zh) * 2023-05-05 2023-08-08 南京航空航天大学 一种恒电流管电极电解加工深小孔的装置

Also Published As

Publication number Publication date
DE2259419A1 (de) 1973-07-19
FR2167552A5 (enrdf_load_stackoverflow) 1973-08-24
JPS4880441A (enrdf_load_stackoverflow) 1973-10-27

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