US3403085A - Electrolytic material removal wherein the charge in the electrolyte is partially dissipate - Google Patents

Electrolytic material removal wherein the charge in the electrolyte is partially dissipate Download PDF

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Publication number
US3403085A
US3403085A US515296A US51529665A US3403085A US 3403085 A US3403085 A US 3403085A US 515296 A US515296 A US 515296A US 51529665 A US51529665 A US 51529665A US 3403085 A US3403085 A US 3403085A
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United States
Prior art keywords
electrolyte
workpiece
stream
cathode
gap
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Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
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US515296A
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English (en)
Inventor
Berger Elmer Joseph
Perin David Clemens
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General Electric Co
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General Electric Co
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Application filed by General Electric Co filed Critical General Electric Co
Priority to US515296A priority Critical patent/US3403085A/en
Priority to FR76384A priority patent/FR1492665A/fr
Priority to GB41085/66A priority patent/GB1162648A/en
Priority to CH1325766A priority patent/CH480909A/de
Priority to NL6613272A priority patent/NL6613272A/xx
Priority to SE12640/66A priority patent/SE325762B/xx
Priority to DE19661565558 priority patent/DE1565558C3/de
Priority to BE712506D priority patent/BE712506A/xx
Application granted granted Critical
Publication of US3403085A publication Critical patent/US3403085A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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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
    • B23H9/16—Making holes using an electrolytic jet

Definitions

  • the term incipient glow in the electrolyte refers to the condition in the electrolyte between a cathode and an anode at which the current density is greater than that which produces the quiet evolution of bubbles in direct current electrolysis. It is in the range of the transition region reported by Kellogg in the Journal of Electrochemical Society, 1950, 97, 133- 142. At the point where an incipient glow appears in the electrolyte, the current decreases with increasing voltage whereas prior to the appearance of an incipient glow in the electrolyte, current increases linearly with increasing voltage.
  • Kellogg region is used herein to refer to the condition in the electrolyte causing at least incipient glow in the electrolyte as it applies to electrolytic material removal. Further into this region, current is low and generally constant as voltage is increased.
  • a tool which can include means to apply a negative charge, at least part of the time, to the electrolyte system is positioned opposite the workpiece across a space or gap.
  • Such gap is small enough to allow the electrolyte stream or jet issuing from the the tool and contacting the workpiece to be placed in a condition causing at least an incipient glow in the electro-' lyte.
  • the gap between the tool, and thus the means to apply the negative charge, and the workpiece will control the size and shape of the cavity resulting from removal of material by this method and apparatus.
  • the co-pend- As one practical method of sensing and controlling this gap, the co-pend-.
  • ing application describes a method for decreasing the starting space between the tool and workpiece at a first rate until a sensing means recognizes an increase, to a certain value, in current flow as a function of gap. Then, when the workpiece and tool are substantially at their operating spacing, the feed rate is reduced to feed the workpiece and tool more slowly one toward the other at an operating feed rate for the actual material removal operation based on the materials and conditions used in the method.
  • the tool nozzle which guides Patented Sept. 24, 1968 or directs the electrolyte and which is frequently vmade of glass, is protected from damage. More important, however, the size and shape of the cavity produced is accurately controlled.
  • Another sensing and control means required in the practice of one specific embodiment in the above identified copending application for complete penetration of the workpiece is means to sense first breakthrough of the workpiece and the associated drop in electric current flow because of the smaller contact area and greater resistance. Under such breakthrough conditions, the feed rate is further reduced or in some cases actually stopped in the practice of that embodiment to allow the complete penetration of the workpiece to be accomplished smoothly.
  • the apparatus required to sense variations in current at several selected times in the specific embodiment of the process discussed above, and as a result to control and vary feed rate as a function of current and gap, employs fairly complex circuitry and a variety of numerous interrelated components. Many of these components are best operated, preset or monitored by an equipment operator for each workpiece.
  • a principal object of the present invention is to provide an improved method for conducting electrolytic material removal of the type described in the above identified co-pending application but which does not require gap sensing at various times in the method and eliminates the need for variable speed feed mechanisms.
  • Another object is to provide an improved, efficient and practical method for the concurrent production of multiple small holes in a complex shaped workpiece.
  • FIG. 1 is a sectional view of an article processed by the present invention
  • FIG. 2 is a partially sectional, partially diagrammatic view of apparatus for the practice of this invention
  • FIGS. 3, 4 and 5 are fragmentary, sectional views of several stages of material removal
  • FIGS. 6 and 7 are fragmentary, sectional views of a comparison between entry holes as a function of starting gap.
  • the method of the present invention provides an automatic gap control and hence a means for eliminating complex variable feed means and gap sensing means, for example, as a function of current, at various points in the above described process.
  • This method controls feed rate by providing an electric conducting means, one example of which is an electrolyte bath, surrounding the charged electrolyte stream.
  • Such means dissipates the electric charge from the electrolyte stream between the cathode and the workpiece at gaps or distances at which material removal would be inacurrate or undesirable.
  • This gap most efficient for material removal, is hereinafter called the equilibrium gap.
  • the size of the equilibrium gap is a function of the amount of electric charge in the electrolyte stream and the ability of the electric charge conducting means, such as an electrolyte bath, to dissipate the electric charge from the charged electrolyte stream. Across the equilibrium gap current is allowed to flow toward the workpiece to remove material at about the same linear rate at which the cathode and workpiece are moved one toward the other.
  • the electrical conducting characteristics of the electrolyte stream and of the electric conducting means, such as the electrolyte bath can be made constant by fixing such variables as applied voltage, temperatures, pressures, size of electrolyte stream, etc. Therefore the equilibrium gap between the cathode and workpiece across which material removal begins need not be sensed or otherwise controlled. Thus a constant feed rate can be used for a single tool or a plurality of tools from which charged electrolyte is directed. Furthermore, because an electrical conductor such as the electrolyte bath surrounds the workpiece surface, added resistance to current flow is eliminated when a hole is first made through a workpiece. Hence no change in feed rate is required for such operation.
  • the improved electrolytic method of this invention for removing material from an electrically conductive workpiece includes the steps of directing a stream of electrically charged electrolyte from a cathode toward the workpiece across an equilibrium gap while at the same time applying between the cathode and the workpiece an electrical potential of a least 300 volts and passing an electrical current sufficient to produce in the electrolyte stream contacting the workpiece a condition causing at A least an incipient glow in the electrolyte as described in the above identified co-pending application.
  • the electrolyte stream is contacted with an electric charge conducing means, such as an electrolyte bath, which will dissipate a sufficient amount of charge to inhibit electrolytic material removal of the workpiece at gaps greater than the equilibrium gap. This inhibition persists until an equilibrium gap is reached if there is relative movement between the cathode and the workpiece.
  • a plurality of electrolyte directing means or nozzles from each of which is directed a charged electrolyte stream can be located at about the same or a variety of levels or positions with respect to the workpiece without affecting the subsequent production of the cavities or holes in the workpiece or the quality and entrance angles of such holes or cavities. Because the electrolyte stream and the electric conducting means such as the electrolyte together control operating gap, the need for accurate mechanical gapping is eliminated.
  • the present invention can be used to produce a variety of holes or cavities in a variety of articles.
  • Such articles include tubes, bars, plates and other members such as the fluid spray head shown generally at in FIG. 1.
  • the perforations or holes 12 through spray head 10 are shown to lie in the same cross sectional plane. It will be understood, however, that the present method can be used to place holes at any point in an article in the same or a variety of cross sectional planes.
  • the nozzles 14 from which'are directed the charged electrolyte stream 26 can protrude in random orientation from the face of such manifold in order to locate the holes wherever desired in the workpiece.
  • the workpiece 10, supported by an electrical insulating means 11, is immersed in an electrical conducting means in the form of an electrolyte bath 18 at least to the extent that the bath will cover the portion of the workpiece surface into which or through which holes or cavities, shown by dotted lines, are to be placed.
  • the electrolyte bath 18 will dissipate, at least a portion of the charge from electrolyte stream 26 directed toward the workpiece from open tip 15 of nozzle 14 to tool 13.
  • Each of the plurarity of tools and their nozzles protruding from the manifold 16 includes, in this embodiment, a cathode 20 from which the electrolyte stream gets its charge although in some instances it may be desirable to use a common cathode.
  • Manifold 16 is movable at least toward and away from workpiece 10. Preferably it is movable in a three dimensional mariner by a conventional motion producing machine such as a press, not shown, but represented schematically by arrows 28. Electrolyte is supplied to manifold 16 for distribution through nozzles 14 by pump 22 from electrolyte supply tank 24.
  • the temperature of the electrolyte in tank 24 and of the electrolyte bath 18 each can be controlled by a heating or cooling means diagrammatically represented at 30 and 32 respectively.
  • This temperature control is a factor in the adjustment of the relative conductivities of the charged electrolyte issuing from nozzle 14 and the electrolyte bath which acts to dissipate at least a portion of the charge from the electrolyte stream 26 until a desired operating gap has been reached.
  • the size of the holes or cavities to be produced in workpiece 10 can be made accurately and uniformly. Their size and shape are controlled without mechanically or electrically sensing the gap between the tip 15 of nozzle 14 and the workpiece, which gap relates to the distance between cathode 20 and the workpiece 10.
  • Cathode 20 for the plurality of nozzles 14 is connected as a cathode to a source of electrical power such as a DC. rectifier which is capable of supplying at least 300 volts.
  • a source of electrical power such as a DC. rectifier which is capable of supplying at least 300 volts.
  • a broadly useful type would supply a current of from a small amount which will allow material removal from a point at which an incipient glow appears in the electrolyte up to about 4 amps, although up to about 2 amps would be sufiicient for most operations.
  • cathodes 20 with an alternating current source of at least 300 volts.
  • Tools 13 are located in manifold 16 in a pattern which relate tips 15 of nozzles 14 to the pattern of holes or cavities desired in the workpiece 10.
  • the capillary portion of nozzle 14 is made sulficiently long, such as D in FIG. 1, to penetrate a desired distance into or through the workpiece.
  • the enlarged portion of tool 13 in which the cathode has been located in the drawing can be adjusted in length in order to eliminate the need for making excessively long capillary portions.
  • the embodiment shown in FIG. 2 could be modified so that the portions of the tools carrying the cathode could be made progressively longer from the center tools outwardly. Because there is no critically with regard to gap sensing, since the electrolyte stream and the electrolyte bath control gap, the tips 15 of nozzles 14 can be located relatively inacurrately and non-uniformly with regard to the distance between the nozzle tip and the workpiece.
  • an electrolyte Prior to operation, an electrolyte is selected for the material of the workpiece. Also, the temperature and pressure at which a desired hole will be produced is selected for the electrolyte stream in relation to the temperature of the electrolyte bath 18.
  • electrolytes used in electrolytic machining and the procedures for selecting operation conditions have been widely described in the literature and in the above identified c0- pending application.
  • Two preferred electrolytes for Ni base alloys are a weight percent sulfuric acid aqueous solution and a 14 weight percent hydrochloric acid aqueous solution. Most convenient to use is an electrolyte bath of the same composition as the electrolyte stream. In this way, if desired, the electrolyte can be recirculated such as from an outlet 40 in the enclosure 42 back to electrolyte tank 24, or perhaps through a filter if desired.
  • the variables of feed rate, electrolyte pressure, electrolyte temperature as well as the voltage applied to cathode can be set and controlled automatically by well known components.
  • the electrolyte stream 26 As the manifold is moved toward workpiece 20, with the electrolyte stream 26 issuing from each nozzle 14 and being charged by cathode 20, the electrolyte stream 26 first contacts electrolyte bath 18 and then tips 15 of nozzles 14 become immersed in bath 18. Because electrolyte bath 18 is an electric conducting means, at least a part of the electric charge is dissipated from the electrolyte stream. However, as shown in FIG.
  • a nickel base alloy tube having a nominal composition, by weight, of 0.1% (max) C; 15% Cr; 3% Cb; 3% Mo; 3% W; 7% Fe; 0.5% A1; 0.6% Ti; 0.006% B; with the balance Ni and incidental impurities, sometimes known as IN 102 nickel base alloy.
  • the tube had a wall thickness of 0.0 Accurately dimensioned holes were placed repeatedly through both walls of the tube over a distance of about 0.19" through the two walls and the central cavity at an applied voltage of 470 volts and a total of 7.1 ampere current for the 12 tubes.
  • the electrolyte used for the electrolyte stream as well as for the electrolyte bath acting as the electric current dissipating means was an aqueous solution of 10 weight percent sulfuric acid.
  • the temperature of the bath and the temperature of the charged electrolyte was maintained at about F., with an electrolyte pressure of between 40-60 p.s.i.
  • This combination of voltage and current which produced a condition causing at least an incipient glow in the electrolyte stream, allowed a cutting rate of 0.06" per minute through the tube wall.
  • hole size can be controlled and varied between 0.02-0.03" for the nozzles used.
  • the nozzle was a drawn glass capillary tube having an inside diameter of 0.015" and a wall thickness of about 0.001".
  • An electrolytic method for removing material from an anodic workpiece through the use of a hollow tool having a dielectric wall encasing an electrical cathode, the tool terminating in an electrolyte directing nozzle comprising the steps of: directing the electrolyte from the cathode through the nozzle in a charged electrolyte stream toward and in contact with the anodic workpiece across an equilibrium gap; concurrently applying an electrical potential of sufficient intensity through the electrolyte stream so that the current passed between the cathode and the workpiece by the potential produces in the electrolyte stream at least an incipient glow wherein the currentvoltage relationship in the electrolyte is at least in the Kellogg region; while at the same time charged electrolyte stream toward and in contact with the anodic workpiece across an equilibrium gap; while at the same time applying between the cathode and the workpiece an electrical potential; contacting the stream of charged electrolyte with means to dissipate a sufficient amount of the charge from the electrolyte stream
  • the potential applied between the cathode and workpiece is 300-1200 volts with the current flow not exceeding 4 amps.
  • the potential is maintained within the range of about 400-800 volts with the current flow not exceeding about 2 amps;
  • the temperature of the electrolyte stream and the electrolyte bath being about 70-200 F.
  • the charged electrolyte stream being directed under a pressure of about 40-60 p.s.i.

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  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Electrical Discharge Machining, Electrochemical Machining, And Combined Machining (AREA)
US515296A 1965-12-20 1965-12-20 Electrolytic material removal wherein the charge in the electrolyte is partially dissipate Expired - Lifetime US3403085A (en)

Priority Applications (8)

Application Number Priority Date Filing Date Title
US515296A US3403085A (en) 1965-12-20 1965-12-20 Electrolytic material removal wherein the charge in the electrolyte is partially dissipate
GB41085/66A GB1162648A (en) 1965-12-20 1966-09-14 Improvements in Electrolytic Material Removal Method
CH1325766A CH480909A (de) 1965-12-20 1966-09-14 Verfahren zum elektrolytischen Materialabtrag an einem Werkstück
FR76384A FR1492665A (fr) 1965-12-20 1966-09-14 Procédé d'usinage par enlèvement électrolytique de matière
NL6613272A NL6613272A (enrdf_load_stackoverflow) 1965-12-20 1966-09-20
SE12640/66A SE325762B (enrdf_load_stackoverflow) 1965-12-20 1966-09-20
DE19661565558 DE1565558C3 (de) 1965-12-20 1966-09-20 Verfahren zur elektrolytischen Herstellung von Löchern oder Hohlräumen in einem elektrisch leitenden Werkstück
BE712506D BE712506A (enrdf_load_stackoverflow) 1965-12-20 1968-03-20

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US515296A US3403085A (en) 1965-12-20 1965-12-20 Electrolytic material removal wherein the charge in the electrolyte is partially dissipate

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US3403085A true US3403085A (en) 1968-09-24

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US (1) US3403085A (enrdf_load_stackoverflow)
BE (1) BE712506A (enrdf_load_stackoverflow)
CH (1) CH480909A (enrdf_load_stackoverflow)
GB (1) GB1162648A (enrdf_load_stackoverflow)
NL (1) NL6613272A (enrdf_load_stackoverflow)
SE (1) SE325762B (enrdf_load_stackoverflow)

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3557336A (en) * 1967-01-13 1971-01-19 British Iron Steel Research Electrochemical heat treatment
US3793170A (en) * 1971-06-09 1974-02-19 Trw Inc Electrochemical machining method and apparatus
US4131780A (en) * 1976-05-19 1978-12-26 Air Products And Chemicals, Inc. Underwater cutting and gouging torch
US4159407A (en) * 1974-03-23 1979-06-26 Rolls-Royce (1971) Limited Methods and apparatus for electrically machining a work piece
US4980533A (en) * 1987-05-22 1990-12-25 Laszlo Rabian Method and apparatus for electroerosive cutting
US5122242A (en) * 1990-11-13 1992-06-16 Paul Slysh Electrochemical machining process
US5893984A (en) * 1995-10-27 1999-04-13 General Electric Company High aspect ratio EDM electrode assembly
MD208Z (ro) * 2009-10-30 2010-12-31 Институт Прикладной Физики Академии Наук Молдовы Electrod-sculă şi procedeu de prelucrare electrochimică a metalelor
CN116453635A (zh) * 2023-05-06 2023-07-18 南京航空航天大学 一种复合加工材料去除占比计算方法、系统、设备及介质

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE4240537A1 (de) * 1992-12-02 1994-06-09 Siemens Ag Verfahren zum Herstellen einer Siebplatte für einen Brennelement-Fuß und entsprechendes Brennelement

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2741594A (en) * 1950-04-05 1956-04-10 Charles F Bowersett Apparatus for electrolytically penetrating shell casings
US2767137A (en) * 1954-07-15 1956-10-16 Philco Corp Method for electrolytic etching
US3067114A (en) * 1953-12-02 1962-12-04 Philco Corp Semiconductive devices and methods for the fabrication thereof
US3085055A (en) * 1954-03-26 1963-04-09 Philco Corp Method of fabricating transistor devices
US3184399A (en) * 1960-09-23 1965-05-18 Philco Corp Electrolytic etching of semiconductors utilizing a.c. bias
US3267014A (en) * 1963-07-11 1966-08-16 Philco Corp Process for rapidly etching a flatbottomed pit in a germanium wafer
US3357912A (en) * 1963-04-02 1967-12-12 Inoue Kiyoshi Ion-control system for electrochemical machining

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2741594A (en) * 1950-04-05 1956-04-10 Charles F Bowersett Apparatus for electrolytically penetrating shell casings
US3067114A (en) * 1953-12-02 1962-12-04 Philco Corp Semiconductive devices and methods for the fabrication thereof
US3085055A (en) * 1954-03-26 1963-04-09 Philco Corp Method of fabricating transistor devices
US2767137A (en) * 1954-07-15 1956-10-16 Philco Corp Method for electrolytic etching
US3184399A (en) * 1960-09-23 1965-05-18 Philco Corp Electrolytic etching of semiconductors utilizing a.c. bias
US3357912A (en) * 1963-04-02 1967-12-12 Inoue Kiyoshi Ion-control system for electrochemical machining
US3267014A (en) * 1963-07-11 1966-08-16 Philco Corp Process for rapidly etching a flatbottomed pit in a germanium wafer

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3557336A (en) * 1967-01-13 1971-01-19 British Iron Steel Research Electrochemical heat treatment
US3793170A (en) * 1971-06-09 1974-02-19 Trw Inc Electrochemical machining method and apparatus
US4159407A (en) * 1974-03-23 1979-06-26 Rolls-Royce (1971) Limited Methods and apparatus for electrically machining a work piece
US4131780A (en) * 1976-05-19 1978-12-26 Air Products And Chemicals, Inc. Underwater cutting and gouging torch
US4980533A (en) * 1987-05-22 1990-12-25 Laszlo Rabian Method and apparatus for electroerosive cutting
US5122242A (en) * 1990-11-13 1992-06-16 Paul Slysh Electrochemical machining process
US5893984A (en) * 1995-10-27 1999-04-13 General Electric Company High aspect ratio EDM electrode assembly
MD208Z (ro) * 2009-10-30 2010-12-31 Институт Прикладной Физики Академии Наук Молдовы Electrod-sculă şi procedeu de prelucrare electrochimică a metalelor
CN116453635A (zh) * 2023-05-06 2023-07-18 南京航空航天大学 一种复合加工材料去除占比计算方法、系统、设备及介质

Also Published As

Publication number Publication date
BE712506A (enrdf_load_stackoverflow) 1968-07-31
CH480909A (de) 1969-11-15
SE325762B (enrdf_load_stackoverflow) 1970-07-06
NL6613272A (enrdf_load_stackoverflow) 1967-06-21
GB1162648A (en) 1969-08-27
DE1565558A1 (de) 1971-12-16
DE1565558B2 (de) 1975-10-02

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