US3224953A

US3224953A - Electrolytic lathe

Info

Publication number: US3224953A
Application number: US103185A
Authority: US
Inventors: John D Russell
Original assignee: Microdot Inc
Current assignee: Microdot Inc
Priority date: 1961-04-07
Filing date: 1961-04-07
Publication date: 1965-12-21
Anticipated expiration: 1982-12-21

Description

Dec. 21, 1965 Filed April '7. 1961 J. D. RUSSELL 3,224,953

ELECTROLYTIC LATHE 6 Sheets-Sheet 1 s: 1 l (kw if @A INVENTOR JOHN D. QUSSELL ATTORNEY Dec. 21, 1965 J D. RUSSELL 3,224,953

ELECTROLYTIC LATHE Filed April 7, 1961 6 Sheets-Sheet 2 MOTOR Raverzsme CIRCLHT 1 MQZO IN VENTOR 1 JOHN D. Dussau. F1G.G L2 BY ATTORNEY Dec. 21, 1965 J. D. RUSSELL 3,224,953

ELECTROLYTIC LATHE Filed April '7. 1961 6 Sheets-Sheet 4 I (I 2 3 7/ 5 I3 P4 22 9 64 74 /R3 R2 ;-1 73 78 72 C2 86 c3 7 f 68 7o 8 W m QAMFLIFIER FIG. l4

INVENTOR JOHN D. RUSSELL.

ATTORNEY United States Patent 3,224,953 ELEQTROLYTIC LATHE John D. Russell, Malibu, Calif., assignor to Microdot Inc, Pasadena, Calif., a corporation of Caiifornia Filed Apr. 7, 1961, Ser. No. 103,135 Claims. ((11. 204-212) This invention relates to apparatus for and method of electrolytically treating elongated metallic articles with a moving stream of liquid for the purpose of shaping the same as desired. This application is a continuation-inpart of my copending application Serial No. 669,144, filed July 1, 1957, now abandoned.

While, more specifically, the article to be treated in accordance with the invention constitutes an electrode of an electric circuit, and the liquid is an electrolyte, the invention includes, in its broader aspects, the treatment of elongated articles of any kind of material by any kind of a liquid which will either act upon them to change their shape or profile, or serve simply for washing or cleaning purposes. In such treatment, the invention contemplates causing a continuously flowing sheet or film of liquid to impinge upon the article, while relative movement is produced between the sheet and the article, longitudinally of the latter.

The electrolytic embodiment of the invention, as above mentioned, finds special utility in the production of metal rods or wires, such for example as the wires used in the manufacture of resistance strain gages. Such wires comprise a main body of very small diameter connected at its ends to leads or terminals of much larger diameter, and an effective method of joining such leads to the main body has long been sought. A specific object of the present invention is to provide a convenient means for the production of a true one-piece wire gage element, by which the problem of forming a proper joint may be eliminated.

While particularly well adapted to the production of strain gage wires, the invention is of course equally applicable to the manufacture of any wire elements in which a fine body is joined to heavier lead Wires, as, for example, in rheostats, potentiometers, etc.

In practice, manufacture is accomplished by starting with a piece of relatively large wire and, by means of the invention, reducing the diameter of the central portion to the desired extent.

A further specific object of the invention is to provide an improved apparatus and method of making what I call a high sensitivity gage element, namely a wire formed in one piece and having sections of alternately large and small diameter.

While, of course, the production of rods or bars having portions of different diameters by means of an ordinary lathe presents no problem, so far as I am aware no method has heretofore been devoloped for producing cylindrical elements having portions of different diameters where the element is in the nature of a fine wire. By the use of the present invention, wires down to .0005 in diameter can be successfully operated upon.

In order that the invention may be readily understood, reference is had to the accompanying drawings, forming part of this specification, and illustrating, by way of example, certain apparatus embodying the invention and by which the method of the invention can be carried out. In these drawings:

FIG. 1 is an elevational view of the portion of a strain gage wire which can be produced in accordance with the present invention;

FIG. 2 is a schematic diagram of one embodiment of apparatus by which the method of the present invention can be practiced;

FIG. 3 is a view in perspective of an embodiment of means for establishing a thin film or sheet of liquid in contact with an elongated element to be treated in accordance with the invention;

FIG. 4 is a plan view, partially schematic, illustrating certain portions of apparatus embodying the invention;

FIG. 5 is a sectional view taken on line 55, FIG. 4, with some parts shown in end elevation;

FIG. 6 is a schematic view illustrating one mode of operation of the apparatus of FIG. 4;

FIG. 7 is an elevational view of a portion of a typical product produced in accordance with the invention along with a comparative illustration of a control element useful in the apparatus of FIG. 4 for producing such product;

FIG. 8 is an elevational view, similar to FIG. 1, of another product of the invention;

FIG. 9 is a diagrammatic illustration of means by which the product of FIG. 8 can be continuously produced;

FIG. 10 is a view, similar to FIG. 7, illustrating the product of the invention shown in FIG. 8 and a coextensive control element useful in producing the same;

FIG. 11 is a view in perspective, partially schematic, illustrating another form of control device which can be used in place of that shown in FIG. 10;

FIG. 12 is a schematic diagram of a further embodi ment of the invention;

FIG. 13 is a view somewhat similar to FIG. 6, showing a slightly modified circuit arrangement;

FIG. 14 is a diagrammatic view illustrating, by way of example, one way in which the electrolytic action may be automatically controlled in accordance with any desired electrical resistance which the finished wire or filament should have;

FIG. 15 is a diagrammatic view illustrating another way in which the electrolytic action can be automatically controlled in accordance with a dimension of the object being shaped;

FIG. 16 is a schematic view illustrating one of the problems which occurs when the electrolytic action is controlled in accordance with the diameter of the object being shaped;

FIG. 17 is a view similar to FIG. 16 illustrating one manner in which the problem explained with reference to FIG. 16 can be overcome;

FIG. 18 is a diagrammatic view illustrating one way for controlling the electrodes in the apparatus of FIG. 17;

FIGS. 19 and 20 are elevational views illustrating further embodiments for establishing a thin sheet of liquid in contact with the element being treated;

FIGS. 21 and 22 are schematic views illustrating the operation of the devices of FIGS. 19 and 20 respectively;

FIG. 23 is a schematic view, partly in section, illustrating another manner of applying the electrolytic liquid to the article being treated;

FIG. 24 is a schematic view, partly in section, illustrating another way in which the electrolytic action can be automatically controlled in accordance with a dimension of the article being treated;

FIG. 25 is a schematic plan View illustrating apparatus for automatically reversing the movement of the carriage;

FIG. 26 is a schematic plan view illustrating another embodiment of apparatus for moving a plurality of articles being treated;

FIG. 27 is an end elevational view, partly in section, along lines 2'7--27 of FIG. 26; and

FIG. 28 is a block diagram illustrating one way in which the electrolytic lathe can be automatically operated.

Referring to the drawings in detail and more particularly first to FIGS. 1 to 3 thereof, 1 represents the main portion of a strain gage, while the leads at each end are indicated at 1 By way of example, it may be explained that such strain gages are usually constructed of Nichrome wire having a diameter of approximately .0007 of an inch, with the leads having a diameter of around .006 of an inch.

While the present invention is of general application and has utility in any art where it is desired to produce a wire or rod having a diameter which varies widely at different points in its length, the invention is especially applicable to the production of the above-mentioned strain gage wire.

My improved apparatus for producing a wire of this character may be described as an electrolytic lathe since it embodies some of the characteristics of a machine tool of this nature. The invention comprises a spreader plate 2 which is preferably downwardly inclined as shown in FIG. 2 and is disposed in a plane transverse to the length of the wire 1 being treated. Near the lower end of the plate 2 is formed an opening 3, through which the wire 1 freely passes. A suitable electrolyte is contained in an elevated tank 4 and is conducted through a conduit 5 including a control valve and a flexible hose 6 to a discharge nozzle at the lower end of this hose. This discharge nozzle is so positioned relative to the plate 2 that the electrolyte issuing therefrom is delivered onto the inclined plate and is spread thereon into a thin film or sheet 7 which flows downwardly by gravity along the upper surface of the plate over and across the opening 3. As a result, the portion of the sheet or film defined by the opening 3 is unsupported, but is nevertheless continuous and uninterrupted. This sheet or film, as it passes over the opening 3, thus impinges against the wire 1 which passes through this opening. The sheet or film, as it impinges against wire 1, lies in a plane which extends transversely of wire 1. The thickness of the sheet is less than the length of the area being treated so that the whole of the area being treated is not subjected to the electrolytic action at any given time. In this manner, a finer degree of control can be obtained.

The electrolyte discharged from the spreader plate 2 is received in a tank 8 from which it is returned by a pump P through

pipes

9 and 10 to the storage tank 4.

A source of direct current such as a battery 11 is provided and one side of this battery is connected by conductor 12 with the spreader plate 2 while the other side is connected by means of a conductor 13 with the wire 1. Thus the sheet of electrolyte flowing along the spreader plate 2 and over the opening 3 is connected in a series circuit with the wire 1 and battery 11, so that current can flow between the sheet of liquid and the wire, at the point of contact between such sheet and wire.

Means are provided, as hereinafter more fully explained, for causing relative movement between the flowing sheet of electrolyte and the wire 1, longitudinally of the latter, so that as this relative movement takes place, the sheet of electrolyte is caused to impinge against successive portions of the wire.

Means are also preferably provided, as hereinafter described, for rotating the wire at the same time, so that all sides of it will be subjected to the action of the electrolyte.

Thus the piece of wire of the maximum diameter indicated at 1 in FIG. 1 may be electrolytically reduced in diameter between any two desired points, by causing a relative movement between the spreader plate and the wire, the rotation of the wire at the same time insuring the production of a wire of truly circular cross section.

Alternatively, if it should be desired to build up or increase the diameter of a fine wire, instead of reducing it, this can be accomplished by simply reversing the connections of the battery to the wire and spreader plate respectively. In this case, metal will be deposited or plated upon the wire by means of the electrolyte.

In FIG. 4, I have illustrate-d, more or less diagrammatically, an arrangement of apparatus for automatically carrying out the above described steps.

In this figure, I have illustrated a pair of chucks 14 between which the wire 1 is stretched and each of which is constructed to grip the end of this wire. These chucks are rotated in synchronism by means of suitable gearing, such gearing including gears 15 secured to the chucks, which may be made of insulating material such as fiber or plastic, or may be mounted on the chuck shafts by insulating bushings. Meshing with the gears 15 are a pair of pinions 16 secured to a shaft 17 driven by a motor 18. Thus both chucks are driven at exactly the same speed and the wire 1 is thus relieved of any torsional strains.

The pinions 16 are also shown as meshing with a pair of gears 19 secured to the opposite ends of a feed screw 20. Working on this feed screw is a carriage 21, similar to a lathe carriage, and guide rods 22, working freely through the carriage are supported by fixed frame members 23 through which the feed screw freely passes. The spreader plate 2 is mounted on the carriage 21, as shown in FIGS. 4 and 5. The electrical connection between the battery 11 and the wire 1 and spreader plate 2 is effected by means of a contact strip 28 against which bears a contact 27 mounted on the carriage 21 and connected with the wire 12 extending from the battery. It will be seen that the circuit is completed by means of the wire 12 connecting the contact strip 28 with the spreader plate, the chucks 14 being connected with the other side of the battery.

The exact portion of the length of the wire 1 which is subjected to the electrolytic action is determined by the length of the contact strip 28. As indicated in FIG. 6, this contact strip has a length L which is the same as that portion of the wire 1 which it is desired to shape. The carriage itself may have a traverse such as indicated by the distance L which is much greater than the length of wire which it is desired to shape, but the fact that the contact 27 runs off the contact strip 28 at each end serves to interrupt the current at these points, and thus prevents any electrolytic action taking place. Thus, although the carriage and spreader plate may traverse a long length of the wire 1, only the portion of such wire equal in length to that of the contact strip 23 is subjected to electrolytic action, the portions beyond the desired length remaining in their original condition, notwithstanding that the liquid may impinge against them.

The arrangement for interrupting the current at definite points in the length of the wire 1, as above described, results in the production of an article such as shown in FIGS. 1 and 6 in which the ends of the treated wire terminate abruptly in shoulders at the untreated portions. It may be desirable, however, to provide a construction in which the shoulders at the ends of the treated portion of the wire are not abrupt but tapering. This is illustrated in FIG. 7 in which the main body of the wire is shown at 1 This effect can be produced by arranging resistances 29 at each end of the contact strip 28. Thus as the contact or slide 27 rides over these resistances, the current flowing through the electrolyte and wire will be gradually reduced, thus producing a corresponding reduction in the amount of etching or electrolytic action.

It will be understood that one of the characteristic features of the invention, especially when used to produce a finished article such as shown in FIG. 7 is the fact that the electrolytic action takes place over only a very small area at any one time. In other words, it is strictly local. This of course results from the fact that the sheet of film 7 of electrolyte is extremely thin, and impinges edgewise on the wire or other element being treated.

In FIG. 8 I have illustrated what I call a high sensitivity gage element, namely, a one-piece element having zones or sections of alternately large and small diameter. The small diameter portions are designated by the numeral 1 as before, while the larger diameter portions are indicated at 1 1 and 1 In order to automatically produce an element having a profile of this kind, I may employ, in place of the contact strip 28 shown in FIG. 4, a contact strip 28 having thereon spaced sections or segments of insulation, 28*, as shown in FIG. 10. In this FIG. I have also reproduced an element similar to that illustrated in FIG. 8, for comparison.

As the slide 27 of FIGS. 5 and 6 moves along this contact strip 28 the circuit will be completed when the slide engages the metal portions of the strip 28 and the circuit will be interrupted when the slide rides upon the insulated portions 28*. The result is that the electrolytic or etching action takes place while the slide is in contact with the conducting portions of the strip, thus reducing the diameter of the wire for corresponding portions of its length, as indicated at 1, and when the slide is passing over the insulated sections 28*, no electrolytic or etching action takes place and the corresponding portions of the wire retain their original diameter as indicated at 1 and 1 Instead of a commutator of the type shown in FIG. 10, I may employ a rotary commutator such as illustrated in FIG. 11. As shown in this figure, this commutator comprises a metal disc 30 mounted on a shaft which may be the feed screw of FIG. 4. Oppositely disposed segments 31 of insulating material are mounted on the face of the disc 30, and a contact brush 32 bears upon the face of the disc, this contact brush being connected with the battery and etching or shaping circuit. As shown, the insulating sector-shaped segments 31 each extend through approximately 90 so that a conducting surface of the same extent lies between them. In other words, as the disc rotates, the etching or shaping circuit is closed for one-fourth of a revolution and is then interrupted during the next quarter revolution, etc. This would produce a finished article such as shown in FIG. 8, except that the lengths of the alternately large and small sections would be equal.

While in the preceding figures I have illustrated arrangements in which the wire is held stationary while the spreader plate and sheet of liquid move longitudinally thereof, and where relatively short pieces of wire are being treated, one at a time, in FIG. 9 I have illustrated quite a different arrangement in which the wire travels while the spreader plates remain stationary, and long lengths of wire are treated continuously. In this case, the wire is carried by reels 33, so that it is unwound from one and wound upon the other. In order to rotate the wire, as in the preceding figures, the reels 33 themselves must rotate in planes at right angles to the portion of the wire which is being treated.

It will be noted that in FIG. 9 I have illustrated a series of spreader plates 2 through all of which the wire passes successively, and it will be further noted that some of these spreader plates, as for example the first three, are not connected in any way with the electric circuit. These preliminary spreader plates, the nozzles of which may be supplied with plain water or any desired cleansing solution, serve merely to rinse and wash the wire as it travels along. It will be understood, of course, that although these preliminary spreader plates do not produce any electrolytic action, they do nevertheless provide continuously flowing sheets of liquid through which the wire passes, just as described in connection with FIGS. 2 and 3.

Following the rinsing and washing spreader plates I have illustrated a plurality of such plates connected with the electric circuit as before and supplied with a suitable electrolyte. By providing a plurality of spreader plates with their flowing sheets of electrolyte, all of the etching or shaping is not done in a single step but is accomplished progressively as the wire passes through successive sheets of electrolyte.

In order to continuously produce an article of the desired shape or profile, such, for example, as that shown in FIG. 8, a suitable commutator 34, for completing or interrupting the circuit at the proper times, must be provided. It will also of course be understood that the spacing of the electrolytic spreader plates, as illustrated at the right in FIG. 9, must be related to the lengths of the alternating small and large sections of the Wire produced, and the master commutator 34 will serve to turn the current off and on to all of the spreader plates simultaneously, in proper timed relation, so that etching will take place at all of them during the same time intervals, and will be interrupted at all of them during alternate intervals.

FIG. 12 illustrates a further embodiment of the invention in which the electrochemical action on the work is controlled directly in response to the dimension of the work substantially at the point where the Work is being treated. In this embodiment of the invention, an optical image of the work, such as the wire 1, is projected upon a sheet of ground glass 35 by means of light source 36 and lens 37, the image 38 appearing as a shadow on the ground glass. Two

photoelectric cells

39 and 40, advantageously of the self-generating type, are arranged to follow the repective edges of the image on ground glass 35. Thus, each

photoelectric cell

39, 40 can be mounted on a support 41, I

42 adjustable by

lead screws

43 and 44 disposed transversely of the ground glass 35. Lead screw 43, carrying photoelectric cell 39, is driven by a servo motor 45 controlled by the photoelectric cell 39 through an amplifier 46 and a conventional line follower circuit. Thus, such conventional circuit may be of the type controlling the motor to rotate lead screw 43 in one direction in response to a no light condition of the photo cell and in the opposite direction in response to a light condition. Similarly, the photoelectric cell 40 is caused to follow the other edge of the image 38 by means of an identical servo motor 47 and amplifier 49.

Mechanically coupled to the

photoelectric cells

39 and 40 are two slide contacts 50 and 51 respectively, engaging a resistance 52. The resistance 52 is connected to control the output of an oscillator and amplifier indicated at 53, such output being supplied to a magnetic recorder 54. Thus, the effect of the magnetic recorder is to establish a record, on any suitable magnetic record medium, indicative of the varying position of the sliding contacts 50 and 51, and thus indicative of the positions of the

photoelectric cells

39 and 40, and therefore of the transverse dimension of the work.

The magnetic record medium is passed continuously through a magnetic reproducer 55 and the signal therefrom supplied, through an amplifier 56 and a rectifier 57, to the etching or shaping circuit.

By conventional circuit design, the oscillator and amplifier 53 and the amplifier 56 and rectifier 57 are constructed to supply current to the etching circuit only when the value of the resistance between slide contacts 50 and 51 exceeds a predetermined amount. Thus, etching of the work takes place only as the dimension thereof at any point is in excess of a predetermined value, and, as a result, an article is produced having a uniform diameter throughout.

Referring again to FIGS. 2 and 6, it is found that when the current is fed always to one end of the article being shaped there is a tendency for the electrolytic action at that end to be excessive or greater than at the portion adjacent the other end, thus giving rise to an objectionable lack of uniformity. This variation in the electrolytic action is due to the resistance of the wire or filament itself. In order to overcome this, and equalize the action, I may feed the electrolytic current to the article alternately from opposite ends.

An arrangement for doing this is illustrated in FIG. 13 Referring to this figure, I provide a stationary contact strip 28. This is similar to the contact strip 28 of FIG. 6, except that it is made /2 the length of the article being treated. It is engaged by a contact 27, carried by the spreader plate 2, as before, but in this case this contact and strip, instead of controlling the electrolytic circuit directly, controls the circuit of a relay. The winding 58 of this relay is connected by wire 13 with the spreader plate, and by wire 59 to one side of a source of current 60, the other side of which is connected by wire 61 with the strip 28. The winding 58 actuates a pivoted armature 62, urged away from the winding by a spring 63, and arranged to play between two

fixed contacts

64 and 65. These contacts are connected by

wires

66 and 67 with the

ends

1 and 1 of the article being treated. The armature 62 is connected to one side of a source of current 11, the other side of which is connected by

wires

12 and 13 with the spreader plate 2.

It will be understood that, as shown in FIG. 13, the contact strip 28 terminates at a point midway of the length of the article being treated. Also the contact 27 is shown as in engagement with the strip 28', so that the relay circuit above traced is closed, the relay is energized, and the armature pulled down into engagement with contact 65. Electrolytic current then flows from source 11 to the end 1 of the article, and thence through the article to the spreader plate, and back to the source through

wires

13 and 12.

Assuming that, in the position shown in FIG. 13, the spreader plate is moving from right to left, the contact 27 will, in the next instant, slip off of the strip 28 and thus break the relay circuit. The relay is thereupon deenergized, the spring 63 pulls the armature up into engagement with the contact 64, and current is then fed from the source 11 to the right-hand end 1 of the article. This will continue while the spreader plate moves to the lefthand end of the article, and back again to the middle. When it reaches the middle, the contact 27 will engage the strip 28' and the electrolytic current will again be fed to the left-hand end of the article. This will continue while the spreader plate travels to the right-hand end of the article, and back to the middle again.

Thus it will be seen that, as the spreader plate reciprocates, current is fed alternately to opposite ends of the article, shifting from one end to the other as the spreader plate passes the middle.

While in FIG. 12 I have shown means by which the electrolytic action on the work is automatically controlled in response to the dimension of the work, I also contemplate automatically controlling the electrolytic action in accordance with the electrical resistance of the.

work, such as a wire or filament. Although this may be accomplished in other ways, it may advantageously be done by including the Wire in one arm of a Wheatstone bridge.

Such an arrangement is shown in FIG. 14. In this figure is illustrated a bridge in one arm of which the work, such as wire 1, is included. It will, of course, 'be understood that the spreader 2, shown in this figure, is mounted to be reciprocated as in FIG. 4, while the wire is rotated.

The bridge has three

other arms

71, 72 and 73, and in the

arms

71 and 72 are included equal fixed resistances R and R In the arm 73 is included an adjustable resistance R The electrolytic circuit includes a source 11 of direct current, as before, connected with the spreader and the work by

conductors

12 and 13, the latter including the armature 68 of a relay, and a pair of contacts positioned to be bridged by such armature. This armature is moved to closed position by a relay winding 69, connected to the output side of an amplifier 70, and is Ibiased to open position by a spring 86.

In order to prevent the possibility of any interaction between the monitoring and electrolytic circuits, I preferably employ an alternating current for the former. A source 74 of alternating current is connected by conductors 75 and 76 to two

opposite corners

77 and 78 of the bridge. The other two

opposite corners

79 and 80, are connected by conductors 81 and 82 with the control input side of the amplifier 70, supplied with current by a cord and plug 85. The wire 1, being treated, is connected between the corners 77 and of the bridge. Variable condensers C and C are advantageously included in a cross-connection 83 between conductors 75 and 76, the mid-point between these condensers being connected by a conductor 74 with the corner 79 of the bridge. This is for the purpose of balancing the reactive components of the alternating current. A condenser C is also included in the conductor 82.

In operation, the resistance R is set at a point equal to the desired resistance of the finished work or wire. As long as this resistance is less than that at which R, is set, the bridge will be unbalanced, and alternating current will flow over the circuit 81, 82 to the amplifier, thus holding the relay contacts 68 closed, and permitting the electrolytic vcurrent to flow through the spreader plate and work. As the electrolytic action progresses, the work or wire is gradually reduced in diameter and its resistance correspondingly increased. Finally, when this resistance reaches the value to which R has been set, the bridge is balanced, no current flows in the circuit 81, 82, and the relay 68 opens, thus interrupting the flow of electrolytic current.

In FIG. 15 is shown a system for controlling the etching action in accordance with the diameter of the wire, the system comprising a linear motion transducer which includes a primary coil 91, a pair of secondary coils 92 and 93 connected in series combination, and an iron slug 94 mounted for movement between the primary and secondary coils. Power is fed from an oscillator 95 to primary coil 91 which induces at the output of the secondary coils a voltage proportional to the position of the slug 94.

The slug is connected to a movable jaw 96 disposed opposite a stationary jaw 97, wire 1 passing between the jaws so that changes in the diameter cause the movable jaw to actuate slug 94.

Jaws

96 and 97 are located so that when there is no wire between them, the slug is positioned above the neutral point to prevent the slug from passing through the null. If the slug could pass through the null, the output voltage would increase with decreasing diameter so that the device would be an electronic wire cutter.

The output from secondary coils 92 and 93 is fed to an amplifier 98 where the signal is amplified and fed to a rectifier 99. A fixed resistor 100 and a variable resistor 101 are connected in series across a battery 102 to bias the output of rectifier 99 so that, at a predetermined diameter of wire 1, the etching action would stop. The rectifier is connected so that the positive voltage is applied to electrode 103 and so that the negative voltage is applied to wire 1. Electrode 103 contacts the electrolyte and can be a spreader plate of the type previously described.

In operation, as wire 1 passes between

jaws

96 and 97, variations in the diameter of the wire move slug 94 to produce an output voltage from transducer 90 proportional to the variation in diameter. The output voltage is amplified and rectified so that variation in diameter of a wire alters the etching voltage in the direction tending to offset such variation. Thus, an increase in the diameter of wire 1, as sensed by the movable jaw 96, increases the etching voltage so that the electrolytic action etches away the increased diameter portion at a greater rate than that required for lesser diameter portions. Likewise, a decrease in the diameter of wire 1 decreases the etching voltage.

In operating the system shown in FIG. 15, a problem sometimes occurs which is best understood with reference to FIG. 16. After several passes have been made, the diameter of portion 1 is substantially greater than that of wire 1, and a tapered portion 104 extends between

portions

1 and 1. When the sheet of electrolyte flows over the tapered portion 104, there is a tendency for some of the fluid to flow downwardly over the tapered portions so that a greater quantity of liquid flows over portion 195. As movable jaw 96 starts to climb the taper, the etching voltage is increased and thereby causes portion 105 to be necked down, as illustrated in FIG. 16, and to produce an imperfect object.

One way to prevent this is to attenuate the etching voltage and effect a more gradual cutofi. Another way to prevent the necking down is illustrated in FIGS. 17 and 18. As shown in FIG. 17, a pair of

electrodes

106 and 107 are mounted upon but electrically insulated from movable jaw 96, the electrodes being insulated from each other and spaced apart longitudinally of wire 1. Dependent upon the direction of motion, one of the electrodes is leading and the other is lagging.

Electrodes

106 and 107 are connected to a double-pole, double-throw relay, indicated generally by numeral 108, having a coil 108 connected to reverse the electrodes from leading to lagging when the lathe reverses. Wires 109 are connected to hte output of rectifier 99, the wires being further connected to an electronic thyratron control switching system, indicated generally by numeral 110 so that the etching voltage is switched, by means of a pair of single-pole, single-throw switches 110* and 110, from the leading electrode for increasing diameters to the lagging electrode for decreasing diameters.

Another method of preventing the necking down would be to narrow the stream of electrolyte as it passes across the wire. One way of doing this is illustrated in FIG. 23 and includes a probe 111 having a central bore 112 through which the electrolyte flows over wire 1, probe 111 being connected to tubing 6. The stationary jaw is also provided with a passage 113 to receive the electrolyte flowing over wire 1.

It sometimes happens that when spreader plates of the types shown in FIGS. 3 and 3 are used, wire 1 moves in an unpredictable fashion relative to the spreader plate and thereby produces unwanted etching action. To prevent this, it is desirable to confine the movement of wire 1, in the vicinity of the spreader plate, so that unwanted movement is prevented and higher etching voltages can be employed to increase the cutting rate. Two embodiments for accomplishing this are shown in FIGS. 19 and 20. As'shown in FIG. 19, a spreader plate 115 of con ductive material, is mounted on a rigid plate 114 of insulating material, plate 114 being provided with an elongated slot 114a for adjustably mounting the same. A jewel rest 116 is mounted beneath the spreader plate 115 on plate 114. Plate 114 has an aperture 117 so that the wire can pass between the lower edge of spreader plate 115 and the upper surface of rest 116. Plate 114 is mounted so that rest 116 produces an upward force, in the direction of the arrow in FIG. 21, causing wire 1 to pass by plate 115 at a point spaced from the longitudinal axis of rotation of chucks 14. One of the chucks 14 is biased by a tension spring 118 to maintain wire 1 in engagement with rest 116. With this construction, it is obvious that as the diameter of wire 1 decreases, the distance from the upper portion of wire 1 to plate 115 becomes greater.

If it is desired to maintain the distance between wire 1 and the spreader plate constant, the spreader plate can be mounted as shown in FIG. 20. In this embodiment, plate 114 is provided with an inverted V-shaped end 119 which engages wire 1. Plate 114 is mounted oft center from the axis of rotation of chucks 14 and pushes downwardly on wire 1 in the direction of the arrow in FIG. 22 so that spring 118 maintains wire 1 in engageemnt with end 119. Thus, the distance between the lower edge of plate 115 and the adjacent surface of wire 1 remains constant.

It has also been found that with a given etchingvoltage and a given electrode spacing, the etching action can be controlled in accordance with the flow rate of the electrolyte. One embodiment for doing this is illustrated in FIG. 24. As shown, wire 1 passes over a fixed jaw 120 disposed opposite a movable jaw 121 which engages the upper edge of wire 1. Jaw 121 is connected to actuate a valve 122 which controls the flow of electrolyte from a reservoir 123 over wire 1. Thus, an increase in the diameter of wire 1 causes an increased flow rate and hence an increased etching action. Likewise, a decrease in diameter decreases the flow rate and etching action.

Since the etching action is fairly slow, it is desirable under many circumstances to construct the lathe so that several wires can be concurrently formed. One embodiment for accomplishing this is illustrated in FIG. 26 and includes a reversible electric motor 124 which drives a spindle 125. A pair of

carriages

126 and 127 are mounted for movement along a pair of guides 128. Chucks 14 are mounted on

carriages

126 and 127 in opposed positions and support a plurality of wires 1 therebetween. Spindle drives gears 129 which are connected to rotate worm gears 130 and a pair of idler gears 131. Gears 131 drive gears 132 which rotate chucks 14. A stationary screw 133 cooperates with gears 131) to move the

carriages

126 and 127 along guides 128. Each of wires 1 is electrically insulated from the other wires so that the etching voltages can be controlled for each wire. One manner of doing this includes constructing

carriages

126 and 127 of insulating material, gears 132 and 129 of brass or other suitable metal and gears 131 of glass fiber or other suitable insulating material. Thus, wires 1 are supported in a manner electrically insulated from each other so that the voltage applied to one is not applied to the other. At the end of each pass, motor 124 is reversed by a pair of limit switches 134 mounted to engage the carriages. Note also in this embodiment that the wires are moved relative to the spreader plates both longitudinally and rotationally, the spreader plates being indicated by the dotted boxes 135.

Carriages

126 and 127 can be also driven by a unidirectional motor. As shown in FIG. 25, a unidirectional motor 136 drives a gear 137 which in turn is meshed with gears 138. Gears 138 are connected to solenoid actuated clutch-brakes 139 and 140, the output of these devices being connected to a diiferential indicated generally by numeral 141 having an output gear connected to drive spindle 125. Clutch-brakes 139 and are alternately operated in response to actuation of limit switches 134 controlled by the position of

carriages

126 and 127 so that when, for example, clutch-brake 139 is actuated, spindle 125 is driven in one direction and thereby causes the carriages to move along the guides in one direction and when clutch-brake 140 is actuated, the spindle 125 and the carriages are driven in the opposite directions.

There is shown in FIG. 28 a system for automatically controlling an electrolyte lathe to concurrently. shape a plurality of wires. The system comprises a power supply 142 connected to a relay system 143 for supplying power to operate a motor 144, a pump 145, a buzzer 146 to etch the wires being shaped. An on-ofl? button 147 is connected to the relay system 143 and controls the operation of the lathe. After the lathe has been turned on by pressing the on-ofi button and has been loaded by placing the wires in the proper chucks, a start button 148 is pushed to begin a production cycle. When the production cycle is complete, the pump is operated to return all the electrolyte which has flowed over the wires to a reservoir and buzzer 146 is turned on to notify the operator that the cycle is complete. The buzzer is turned off by actuating a push button 149 connected to the relay system.

When the start button is pressed to begin a cycle, the relay system connects the motor to the power supply whereby the motor reciprocates and rotates the wires relative to the sheets of electrolyte flowing over the wires. Limit switches 150 are arranged to reverse the direction of reciprocation at the end of each pass.

The flow of current between the electrode 151, i.e., the associated spreader plates and wires, is controlled by a suitable etching controller 152. During the first pass, a

1 l relatively low etching voltage is applied to each pair of electrodes to clean the wires. At the end of the first pass, and during the second pass, a higher etching voltage is applied to etch each wire.

At the end of the second pass and every subsequent pass, the relative motion and the etching action are stopped and a master stepping switch 153 connects the wires, one at a time, to an electronic potentiometer 154 which measures the resistance of each wire. A plurality of stepping switches 155, one for each wire being shaped, are actuated by the potentiometer so that, when the resistance of each wire increases beyond a predetermined value, the etching voltage is decreased. When the potentiometer indicates that the resistance of each wire has reached a value indicative that the shaping of such wire is complete, the stepping switch associated with such wire goes home and no further etching of that wire takes place. When all the stepping switches are home, the production cycle is complete and the buzzer goes on.

While several embodiments have been shown, it is obvious that some of the details of some can be substituted for some of the details of others and that the various ways for controlling the electrolytic action can be combined. For example, the etching action can be controlled in acordance with both the resistance and the diameter of the wire. It will be obvious to those skilled in the art that many changes can be made in the details and arrangement of parts without departing from the scope of the invention as defined in the appended claims.

What is claimed is:

1. An electrolytic lathe comprising work holding means adapted to rotatably support a work piece, reservoir means adapted to contain a supply of electrolyte, an inclined spreader plate means having an opening therein for passage of said work piece and capable of causing said electrolyte to flow in a sheet over said work piece as said work piece is being rotated, said spreader plate means being designed and installed to provide a sheet of electrolyte over said opening having a thickness less than the length of the portion of the article being treated, reciprocatory means to produce relative motion between said work piece and said spreader plate means so that said electrolyte contacts said work piece at successive portions, and electrical means adapted to cause current to flow through said electrolyte and said work piece.

2. An electrolytic lathe for shaping a wire comprising holder means for supporting said wire, spreader plate means having an opening therein for passage of said wire and capable of causing an electrolyte to flow in a sheet over said wire in a plane transverse to the axis of said wire, said spreader plate means being designed and installed to provide a sheet of electrolyte having a thickness substantially less than the length of the portion of said wire being shaped, drive means for producing relative rotation between said spreader plate means and said wire, said driving means being further operative to produce between said spreader plate means and said wire relative reciprocation in a direction along said wire, and electrical means adapted to connect said sheet and said wire to a source of current.

3. An electrolytic lathe in accordance with claim 2 and additionally including means for varying the flow of current to control the electrolytic action.

4. An electrolytic lathe in accordance with claim 2 and additionally including means for varying the flow of current to control the electrolytic action in accordance with the resistance of said wire.

5. An electrolytic lathe for producing a filament having a pair of terminal leads and a main body extending between said leads comprising a pair of chucks adapted to be connected to said leads for rotatably supporting said filament, drive means for rotating said chucks to rotate said filament, spreader plate means having an opening therein for the passage of said main body and capable of causing a sheet of electrolyte to flow over said main body portion in a plane transverse to said filament and being of a thickness less than the length of said main body, second drive means for producing relative reciprocation between said filament and said spreader plate means in a direction along said main body, and electrical means adapted to connect said filament and said sheet to a source of current.

6. Apparatus for electrolytically treating an elongated metallic wire having at least two portions of different diameters, comprising holding means for mounting the wire for rotation about its axis, spreader plate means having an opening therein for passage of said wire and capable of producing a continuously flowing sheet of electrolyte disposed in a plane extending transversely across said wire, an electric circuit connecting said sheet of electrolyte and said wire in series, drive means for producing relative longitudinal movement between said spreader plate means and said wire, and control means adapted to selectively connect said circuit to a source of current so that current flows through said electrolyte and said wire only when said electrolyte contacts that portion of said wire of a certain diameter.

7. Apparatus for producing an elongated metallic wire element having at least one portion of a predetermined diameter and at least one other portion of a diameter less than that of said first portion, comprising holding means for mounting said wire for rotation about its axis, spreader plate means having an opening therein for the passage of said wire and capable of producing a continuously flowing sheet of electrolyte disposed in a plane extending transversely across said wire, drive means for producing relative longitudinal movement between said spreader plate means and said wire longitudinally of said wire, so that said sheet is caused to impinge against successive portions of said wire, and an electric circuit adapted to connect said flowing sheet of electrolyte and said wire in series to a source of current and including means to interrupt said connection so that current flows only when said electrolyte impinges against that portion of the wire of smaller diameter.

8. Apparatus for electrolytically shaping an elongated metal article comprising spreader plate means having an opening therein for passage of said article and capable of producing a continuously flowing sheet of electrolyte disposed in a plane extending transversely across the axis of the article to be shaped, a source of current, a circuit connecting said flowing sheet of electrolyte and said article in series, drive means for producing relative movement between said spreader plate and said article longitudinally of the latter, so that said flowing sheet from said spreader plate is caused to impinge against successive portions of said article, as such movement takes plate, and means for automatically interrupting said circuit at certain definite points in such movement.

9. Apparatus for electrolytically shaping an elongated metal article comprising spreader plate means having an opening therein for passage of said article for producing a continuously flowing sheet of electrolyte disposed in a plane extending transversely across the axis of the article to be shaped, a source of current, drive means for producing relative travel between said spreader plate means and said article longitudinally of the latter so that said flowing sheet from said spreader plate is caused to impinge successively on different parts of said article as such travel takes place, and electrical means for automatically connecting said source in a series circuit with said flowing sheet and article during certain definite portions of such travel, and for automatically interrupting said circuit during other portions of such travel.

10. Apparatus for electrolytically shaping an elongated metallic wire element comprising holding means supporting said element, spreader plate means having an opening therein for passage of said wire element and capable of producing a continuously flowing sheet of electrolyte in a plane extending transversely across said element, drive means for producing relative rotation and axial movement between said spreader plate means and said element sothat said sheet from said spreader plate impinges against successive portions of said element as such movement occurs, means for causing an electric current to pass serially through said flowing sheet and said element, and means for automatically varying said current to shape said element.

References Cited by the Examiner UNITED STATES PATENTS 480,186 8/1892 Elmore et a1. 204-217 X 1,562,846 11/1925 Payne 204-218 X 1,773,135 8/1930 Flanzer 204-212 X 2,068,352 1/1937 Schlacks 204-141 1/ 1943 Hogaboom 204-141 2/ 1946 Venable 204-141 10/1950 Rudorff 204-143 10/ 1952 Pendleton 118-325 9/1956 Pullen 204-211 3/ 1957 Korbelak 204-141 6/1957 Eigler 204-143 3/1958 Barry 204-143 2/1962 Burke et a1. 118-325 FOREIGN PATENTS 10/ 1939 Germany.

2/ 1897 Great Britain.

15 WINSTON A. DOUGLAS, Primary Examiner.

JOHN R. SPECK, JOHN H. MACK, Examiners.

Claims

1. AN ELECTROLYTIC LATHE COMPRISING WORK HOLDING MEANS ADAPTED TO ROTABLY SUPPORT A WORK PIECE, RESERVOIR MEANS ADAPTED TO CONTAIN A SUPPLY OF ELECTROLYTE, AN INCLINED SPREADER PLATE MEANS HAVING AN OPENING THEREIN FOR PASSAGE OF SSAID WORK PIECE AND CAPABLE OF CAUSING SAID ELECTROLYTE TO FLOW IN A SHEET OVER SAID WORK PIECE AS SAID WORK PIECE IS BEING ROTATED, SAID SPREADER PLATE MEANS BEING DESIGNED AND INSTALLED TO PROVIDE A SHEET OF ELECTROLYTE OVER SAID OPENING HAVING A THICKNESS LESS THAN THE LENGTH OF THE PORTION OF THE ARTICLE BEING TREATED, RECIPROCATORY MEANS TO PRODUCE RELATIVE MOTION BETWEEN SAID WORK PIECE AND SAID SPREADER PLATE MEANS SO THAT SAID ELECTROLYTE CONTACTS SAID WORK PIECE AT SUCCESSIVE PORTIONS, AND ELECTRICAL MEANS ADAPTED TO CAUSE CURRENT TO FLOW THROUGH SAID ELECTROLYTE AND SAID WORK PIECE.