US3257300A - Method for electrolytically forming tapered or contoured cavities - Google Patents

Method for electrolytically forming tapered or contoured cavities Download PDF

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Publication number
US3257300A
US3257300A US90438A US9043861A US3257300A US 3257300 A US3257300 A US 3257300A US 90438 A US90438 A US 90438A US 9043861 A US9043861 A US 9043861A US 3257300 A US3257300 A US 3257300A
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United States
Prior art keywords
electrode
cavity
workpiece
side walls
electrolyte
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Expired - Lifetime
Application number
US90438A
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English (en)
Inventor
Lynn A Williams
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Anocut Engineering Co
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Anocut Engineering Co
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Filing date
Publication date
Priority to NL274928D priority Critical patent/NL274928A/xx
Application filed by Anocut Engineering Co filed Critical Anocut Engineering Co
Priority to US90438A priority patent/US3257300A/en
Priority to CH199062A priority patent/CH389123A/fr
Priority to FR888623A priority patent/FR1316113A/fr
Priority to GB6629/62A priority patent/GB1002957A/en
Priority to AT139962A priority patent/AT252405B/de
Priority to US534931A priority patent/US3352774A/en
Application granted granted Critical
Publication of US3257300A publication Critical patent/US3257300A/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
    • B23H3/00—Electrochemical machining, i.e. removing metal by passing current between an electrode and a workpiece in the presence of an electrolyte
    • B23H3/04—Electrodes specially adapted therefor or their manufacture

Definitions

  • the principal object of this invention is to facilitate the formation of cavities having tapered or contoured side walls with a smooth and in some instances with a high finish.
  • Another object is to provide electrodes for the formation of such cavities.
  • Another object is to increase the speed of forming such cavities.
  • Another object is to facilitate the manufacture of suitable tool electrodes for forming such cavities.
  • FIG. 1 is a schematic view in elevation of the work area of apparatus used in the practice of this invention
  • FIG. 2 is a frontal'view showing the working tip of a wedge electrode of this invention
  • FIG. 3 is a side elevation of the electrode of FIG. 2;
  • FIG. 4 is an end view of the electrode of FIG. 2;
  • FIG. 5 is a sectional view of a workpiece showing a preliminary roughing cut
  • FIG. 6 is a similar view of the same workpiece shown in FIG. 5 after finishing the cut to produce tapered side walls;
  • FIG. 7 is a side elevation of an electrode for forming a slot as a first step in the practice of the invention.
  • FIG. 8 is an end view of the electrode'of FIG. 7;
  • FIG. 9 is aside elevation of a finishing electrode
  • FIG. 10 is an end view of the finishing electrode of FIG. 9; j
  • FIG. 11 is a sectional view of a workpiece with a roughing slot formed by the electrode of FIGS. 7 and 8;
  • FIG. 12 is a sectional view of the same workpiece after it has been contoured by the electrode of FIGS. 9 and 10;
  • FIG. 13 is a view, partly in section, of a modified arrangement wherein a solid contouring electrode is used with the electrolyte being introduced through ahole in the workpiece.
  • the front plate is by the methods shown in the above identified copending applications and the patents issued thereon, it is difficult to produce good accuracy and smooth finish when the surface to be formed deviates more than about 45 to 60 degrees from a plane normal to the direction of advance of the electrode, and this invention is concerned primarily, though not exclusively, with this kind of situation. But, as will be seen, the invention may also be used to produce very smooth surfaces which are substantially normal to the path of advance of the electrode. This is shown, for example, in the electrode of FIGS. 9 and 10 andin the workpiece of FIG. 12.
  • the electrode is arranged in such a way as to cause always a kind of outwardly wedging action against the work material, thereby tending constantly to confine the electrolyte, to maintain its pressure, and to maintain high velocity, then it is possible to secure close conformation of shape between the cavity in the workpiece and that on the electrode. And, at the same time, it is possible to produce a bright, specular finish even though the electrolyte solutions used are not of the kind ordinarily regarded as having electropolishing characteristics.
  • FIG. 1 shows schematically the general configuration of the apparatus.
  • An electrode E is mounted to a manifold M, which is fed with a hose H with electrolyte under a pressure of -100 to 300 psi. at the manifold and at the entrance to the electrode.
  • the manifold M is mounted in turn to a holder H1 which is electrically insulated from the body of the ram, and the ram itself is protected against electrolyte by a collapsible boot B.
  • Direct current of a voltage not appreciably greater than about 18 volts is. supplied from a source of the type disclosed in the copending application of Lynn A. Williams, Serial No.
  • the ram is arranged to be advanced under a positive drive at a predetermined fixed rate in the direction of the arnow toward the Work, thereby moving the electrode linearly into the workpiece.
  • a more detailed description Patented June 21, 1966 aasasco of the type of apparatus which may be used is shown in the copending application of Lynn A. Williams entitled Electrolytic Cavity Sinking Apparatus and Method, Serial No. 73,154, filed September 2, 1960.
  • FIG. 2 shows one form of electrode used in the practice of the invention. It consists of an electrode proper 21, which is made of copper and is mounted in the manifold member M, which, in turn, may be either fastened to or made integrally with a holder plate H1.
  • the manifold M is recessed as shown at 23, and provision is made for connection of a hose through a screw-threaded opening 25.
  • the electrode 21 conforms to the shape of the recess 23 in the manifold, and may be fastened into it by any suitable means, for example, by brazing or soldering.
  • the electrode proper 21 is arranged to feed electrolyte from the recess 23 of the manifold to its working tip by a plurality of feed holes or passages 27.
  • the holes should be about /8" in diameter, and, in general, the more open and free the passage for electrolyte the better.
  • the holes 27 are not carried through all the way to the working tip of the electrode but terminate about A2" to A1 above it, where they are intersected by a transverse slot 29 which is milled into the end of the electrode in such a way as to communicate with the holes 27.
  • the slot may be about wide for an electrode of this size.
  • the slot 29 should be deep enough so as to smoothout the flow from the several holes 27, so that the electrolyte issues smoothly through the slot with a minimum reflection of the pattern of holes through which it previously passed.
  • This electrode is not insulated either on its sides or on its ends, but is left bare for the purpose of producing tapered side walls 30.
  • the electrode may be used in either of two ways. Either it may be simply advanced into a raw piece of work, using the maximum penetration rate which is obtainable, or, preferably, it may be used to enlarge a cavity previously made by a slotting electrode; for example, one like that shown in FIGS. 7 and 8 or as shown in one or more of the previously identified copending application.
  • a cut of this preliminary kind is shown in FIG. 5. There is no basic reason why it could not be produced by conventional machining as well as by electrolytic means, although ordinarily formation of cavities of this sort can be accomplished more quickly by use of electrolytic machining techniques than by conventional methods.
  • the width and length of the preliminary cut as shown in FIG. should be about the size of the working tip of the tapered electrode shown in FIGS. 2, 3 and 4.
  • the method of advancing the tapered electrode directly into a workpiece without making a preliminary cut can be carried out where the taper on the sides and ends of the electrode is sufficiently great (say, 30 from the line of advance of the electrode). As the angle of taper becomes less, a point is reached where it is necessary to make a preliminary cut like that shown in the workpiece of FIG. 5. This is for the reason that it is not pos sible to maintain a sufficiently fast rate of frontal advance into the work to keep the tapered sides sufficiently close to the work material, which, of course, is being electrolytically removed in a generally sideward direction.
  • FIG. 5 shows the shape of the tapered cavity formed in the same workpiece shown in FIG. 5 by using the electrode of FIGS. 2, 3 and 4.
  • FIGS. 7, 8, 9 and 10 show a simple electrode for making a rectangular cavity.
  • the electrode proper 21 may be made like other electrodes of copper. It is fitted into a recess 23 in a manifold M which, in turn, is fastened to a holder or mounting plate H1.
  • the cavity 23 is fed by an opening adapted to receive a hose connection as at 25.
  • the electrode proper is drilled with feed holes or passages 27, which are closely spaced as previously described in connection with the electrode of FIGS. 2, 3 and 4.
  • a slot 29 is milled into the electrode near its tip, and, then, an additional member serving as a flange plate 31 is fastened to the body of the electrode by brazing or soldering.
  • This additional flange plate is arranged to project beyond the body of the electrode by about .010" to .030 with the purpose of providing clearance for insulating material 33, which is applied to the body of the electrode to prevent excessive side action.
  • FIGS. 9 and 10 is used in order to modify the shape of the cavity to provide radii on all of the side walls.
  • This electrode of FIGS. 9 and 10 is made in substantially the same way as the electrodes previously described herein with like reference indicia referring to similar parts. Here, however, it is not necessary to provide any slot, but, instead, quite large feed holes 27 are used, and these pass directly through the body of the electrode 21 to feed electrolyte into the work area.
  • this type is machined to a shape to provide a full radius as shown at R.
  • This may be any contour which is desired and may be either straight or curved as the work requirements dictate.
  • the electrode of FIGS. 9 and 10 is positioned so that the working tip of this electrode registers with the previously formed cavity. It is not critical that the working face should have identically the same contour as the cavity, but the deviation should not be excessive and, particularly important, there should not be any place where the cavity is so much larger than the finishing electrode that any large amount of the electrolyte will escape through the gap which would thus be formed. Except for this, however, close conformity is desirable but not necessary.
  • the electrode of FIGS. 9 and 10 After positioning the electrode of FIGS. 9 and 10 with respect to the pre-existing cavity, it is then advanced at a fairly rapid rate into the work until it has reached a depth where its working tip is close to the bottom of the previously formed cavity. If this is done rapidly, the result will be to form an accurate contour and to induce a very high finish on the work material.
  • an electrode like that'of FIGS. 7 and 8 has been made as a roughing electrode, its dimensions being 2" in length and in width.
  • the cavity like that shown in FIG. 11 was produced with an infeed rate of advance of .100 per minute using a direct current of 14 volts and an electrode pressure of about 200 p.s.i.
  • the cavity in the workpiece was carried to a depth of .200.
  • an electrode like that of FIGS. '9 and 10 was applied, using a feed rate of .200" per minute, an electrolyzing current at a voltage of 13 volts and a total penetration to a depth of .187".
  • FIG. 13 there is illustrated an arrangement for forming a tapered or contoured cavity without using a hollow electrode
  • the workpiece WK is initially formed with a through cavity 35 by electrolytic or conventional machining techniques.
  • the workpiece is mounted or clamped in. a fixture or bracket 37 having one or more passages 39 therethrough adapted to be placed in communication with the workpiece cavity 3-5. If the workpiece cavity is large or elongate then two, three or more fixture passages 39 fed from a manifold similar in function to the manifold M of FIGS. 2 to 4, 9 and 10, should be provided.
  • the electrode 43 is similar in configuration (for illustration purposes only) to that shown in FIGS. 9 and 10 but is made of a solid block of copper or other suitable material and is mounted directly upon the holder H1 to be connected into the electrolyzing power circuit in a manner to be cathodic. It is formed with contouring radii R which are adapted electrolytically to form contoured surfaces R" on the workpiece WK.
  • the electrode 43 With the electric current turned on and electrolyte being supplied to the rough workpiece cavity 35, the electrode 43 is advanced into the work with a positive feed and at a constant rate.
  • the rough cavity in the workpiece forms a plenum ahead of the advancing workpiece and as the electrolyte escapes from the cavity between the electrode surfaces R and the workpiece the latter is electrolytically eroded to the shape of the surfaces R to have a smooth finish and, depending upon the character of the workpiece material, perhaps a high specular finish.
  • FIGS. 2, 3 and 4 having a rather regular shape
  • other electrodes have also been used in which, while the same general tapered configuration was employed, the actual shape was; the rather complex shape existing between two blades of a turbine wheel, the blades themselves having a twist or camber and, at the same time, a constantly changing section.
  • a preliminary, straightsided cut was made into a disc of material at a point roughly representing the midpoint between two of the blades.
  • the wedge shaped electrode formed to produce the interblade cavity was introduced at a high rate of feed in order to shape and finish the convex side of one blade and, concurrently, the adjoining concave side of the next blade.
  • the electrode should be one in which its section grows larger as it is advanced into the work so as to remove material by side action while at all times forcing the electrode into the cavity to maintain close spacing between the electrode and the work, a spacing of the order of .015 or less while, at the same time, maintaining electrolyte pressure of the order of psi. or more and, at the same time, maintaining high velocity of electrolyte flow.
  • the rate of advance necessary to bring about these conditions will, of course, be determined by the taper. If the taper is shallow, then the electrode may have tobe advanced very rapidly, as rapidly, for example, as an inch per minute or even more. On the other hand, if the taper is steeper then a slower rate of advance will maintain the desired condition.
  • the electrode at the entry to the electrode and with a high electrolyte velocity so as to fill the workpiece cavity beyond the forward end of the electrode so as to make the workpiece cavity a plenum chamber, and advancing the electrode into the workpiece at a rate not greater than about one inch per minute and such that with the electrolyte outflow from the cavity between the cavity side walls and the electrode side walls a very small spacing distance of not greater than about .015 inch will be provided therebetween as the cavity is enlarged to the desired finished shape.

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  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • Mechanical Engineering (AREA)
  • Electrical Discharge Machining, Electrochemical Machining, And Combined Machining (AREA)
US90438A 1961-02-20 1961-02-20 Method for electrolytically forming tapered or contoured cavities Expired - Lifetime US3257300A (en)

Priority Applications (7)

Application Number Priority Date Filing Date Title
NL274928D NL274928A (de) 1961-02-20
US90438A US3257300A (en) 1961-02-20 1961-02-20 Method for electrolytically forming tapered or contoured cavities
CH199062A CH389123A (fr) 1961-02-20 1962-02-19 Procédé pour l'usinage électrochimique d'une cavité à parois évasées
FR888623A FR1316113A (fr) 1961-02-20 1962-02-20 Procédé pour l'usinage d'une cavité de section décroissante ou profilée
GB6629/62A GB1002957A (en) 1961-02-20 1962-02-20 Improvements in or relating to electrolytic machining
AT139962A AT252405B (de) 1961-02-20 1962-02-20 Verfahren und Elektrode zur elektrochemischen Herstellung einer Vertiefung in einem Werkstück aus elektrisch leitendem Material sowie Werkstück zur Verwendung bei einem solchen Verfahren
US534931A US3352774A (en) 1961-02-20 1966-01-17 Apparatus for electrolytically tapered or contoured cavities

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US90438A US3257300A (en) 1961-02-20 1961-02-20 Method for electrolytically forming tapered or contoured cavities

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Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3354073A (en) * 1963-11-22 1967-11-21 Gen Motors Corp Electrical stock removal apparatus
US3547798A (en) * 1967-03-29 1970-12-15 Cincinnati Milacron Inc Electrochemical machining tool
US3547797A (en) * 1967-03-29 1970-12-15 Cincinnati Milacron Inc Apparatus for simultaneously electrochemically machining a plurality of previously formed surfaces of a workpiece
US4522692A (en) * 1983-07-26 1985-06-11 United Technologies Corporation Electrochemical machining a workpiece uniformly using a porous electrode
US5893984A (en) * 1995-10-27 1999-04-13 General Electric Company High aspect ratio EDM electrode assembly

Citations (17)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US178448A (en) * 1876-06-06 Improvement in countersinks
US1435671A (en) * 1922-03-10 1922-11-14 Roessler & Hasslacher Chemical Anode
US1707406A (en) * 1926-12-21 1929-04-02 Electrometallurgique De Montri Furnace electrode
GB335003A (en) * 1929-07-24 1930-09-18 Wladimir Gusseff Method and apparatus for the electrolytic treatment of metals
US2362260A (en) * 1943-12-08 1944-11-07 Harry I Foster Countersinking drill
US2786373A (en) * 1953-12-14 1957-03-26 Patton William Kenneth Straight flute drilling cutter
US2813966A (en) * 1955-03-25 1957-11-19 Elox Corp Michigan Rough and finish machining with stepped electrode
US2818490A (en) * 1952-08-08 1957-12-31 Firth Sterling Inc Means for use in the working of metals by electro-erosion
US2835198A (en) * 1953-09-10 1958-05-20 Brombacher Heinrich Ammunition for firearms
US2844531A (en) * 1954-05-24 1958-07-22 Bell Telephone Labor Inc Method of producing cavities in semiconductive surfaces
US2848401A (en) * 1953-05-07 1958-08-19 Olin Mathieson Method of electrolytically rifling gun barrels
US2909641A (en) * 1958-05-02 1959-10-20 Republic Aviat Corp Tool for electro-shaping
US2982842A (en) * 1957-03-21 1961-05-02 Tuscher Jean Edouard Method for automatically executing cutters and the like shaped parts of revolution through electric erosion
US3019178A (en) * 1959-10-29 1962-01-30 Anocut Eng Co Electrode for electrolytic shaping
US3058895A (en) * 1958-11-10 1962-10-16 Anocut Eng Co Electrolytic shaping
US3095364A (en) * 1959-11-27 1963-06-25 Steel Improvement & Forge Comp Material removal
US3120482A (en) * 1959-11-16 1964-02-04 Anocut Eng Co Apparatus for electrolytic hole sinking

Patent Citations (17)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US178448A (en) * 1876-06-06 Improvement in countersinks
US1435671A (en) * 1922-03-10 1922-11-14 Roessler & Hasslacher Chemical Anode
US1707406A (en) * 1926-12-21 1929-04-02 Electrometallurgique De Montri Furnace electrode
GB335003A (en) * 1929-07-24 1930-09-18 Wladimir Gusseff Method and apparatus for the electrolytic treatment of metals
US2362260A (en) * 1943-12-08 1944-11-07 Harry I Foster Countersinking drill
US2818490A (en) * 1952-08-08 1957-12-31 Firth Sterling Inc Means for use in the working of metals by electro-erosion
US2848401A (en) * 1953-05-07 1958-08-19 Olin Mathieson Method of electrolytically rifling gun barrels
US2835198A (en) * 1953-09-10 1958-05-20 Brombacher Heinrich Ammunition for firearms
US2786373A (en) * 1953-12-14 1957-03-26 Patton William Kenneth Straight flute drilling cutter
US2844531A (en) * 1954-05-24 1958-07-22 Bell Telephone Labor Inc Method of producing cavities in semiconductive surfaces
US2813966A (en) * 1955-03-25 1957-11-19 Elox Corp Michigan Rough and finish machining with stepped electrode
US2982842A (en) * 1957-03-21 1961-05-02 Tuscher Jean Edouard Method for automatically executing cutters and the like shaped parts of revolution through electric erosion
US2909641A (en) * 1958-05-02 1959-10-20 Republic Aviat Corp Tool for electro-shaping
US3058895A (en) * 1958-11-10 1962-10-16 Anocut Eng Co Electrolytic shaping
US3019178A (en) * 1959-10-29 1962-01-30 Anocut Eng Co Electrode for electrolytic shaping
US3120482A (en) * 1959-11-16 1964-02-04 Anocut Eng Co Apparatus for electrolytic hole sinking
US3095364A (en) * 1959-11-27 1963-06-25 Steel Improvement & Forge Comp Material removal

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3354073A (en) * 1963-11-22 1967-11-21 Gen Motors Corp Electrical stock removal apparatus
US3547798A (en) * 1967-03-29 1970-12-15 Cincinnati Milacron Inc Electrochemical machining tool
US3547797A (en) * 1967-03-29 1970-12-15 Cincinnati Milacron Inc Apparatus for simultaneously electrochemically machining a plurality of previously formed surfaces of a workpiece
US4522692A (en) * 1983-07-26 1985-06-11 United Technologies Corporation Electrochemical machining a workpiece uniformly using a porous electrode
US5893984A (en) * 1995-10-27 1999-04-13 General Electric Company High aspect ratio EDM electrode assembly

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Publication number Publication date
AT252405B (de) 1967-02-27

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