US3779887A

US3779887A - Vibratory applicator for electroplating solutions

Info

Publication number: US3779887A
Application number: US00234590A
Authority: US
Inventors: A Gildone
Original assignee: Sifco Industries Inc
Current assignee: Sifco Industries Inc
Priority date: 1972-03-14
Filing date: 1972-03-14
Publication date: 1973-12-18
Anticipated expiration: 1990-12-18
Also published as: FR2176036A1; BR7301786D0; CA989770A; JPS492728A; FR2176036B3

Abstract

A vibratory tool for the brush electrotreatment of metal and especially for electroplating at increased rates of metal deposition as compared with non-vibratory tools. In one form, the apparatus comprises a hand tool having a plating terminal that is preferably fixed with respect to the tool. A housing encompasses the plating terminal and carries a porous dielectric cover in contact with the plating terminal. The cover is wet by electrolyte and rubbed over a workpiece. Power vibratory means positively moves the housing and porous cover with respect to the plating terminal while maintaining the contacting relation between the cover and terminal, so that in use the cover is vibrated with respect to both the workpiece and the plating terminal.

Description

United States Patent [191 Gildone Dec. 18, 1973 viBnAToRY APPLICATOR FOR ELECTROPLATING SOLUTIONS Anthony M. Gildone, Euclid, Ohio Sifco Industries, Inc., Cleveland, Ohio Filed: Mar. 14, 1972 Appl. No.2 234,590

Inventor:

Assignee:

us. Cl. 204/224 R, 204/271 rm. Cl B23p 1/02, C23b-5/76 Field of Search 204/224, 15, 271

References Cited UNITED STATES PATENTS 2,96l,395 ll/l960 lcxi 204/224 R 3,520,792 7/1970 Kerschgens 204/224 R FOREIGN PATENTS OR APPLICATIONS 760,0l6 [0/1956 Great Britain 204/224 Primary ExaminerT. Tufariello Att0rneyWilliam C. Sessions et al.

[5 7] ABSTRACT A vibratory tool for the brush electrotreatment of metal and especially for electroplating at increased rates of metal deposition as compared with nonvibratory tools. In one form, the apparatus comprises a hand tool having a plating terminal that is preferably fixed with respect to the tool. A housing encompasses .the plating terminal and carries a porous dielectric cover in contact with the plating terminal. The cover is wet by electrolyte and rubbed over a workpiece.

Power vibratory means positively moves the housing and porous cover with respect to the plating terminal while maintaining the contacting relation between the cover and terminal, so that in use the cover is vibrated with respect to both the workpiece and the plating terminal.

11 Claims, 5 Drawing Figures PATENTEUDEB18 I975 3,779,887 7 SHEEI 10F 2 SOLUTION VIBRATORY APPLICATOR FOR ELECTROPLATING SOLUTIONS BACKGROUND OF THE INVENTION Electroplating apparatus for brush electroplating is known in the art. Such apparatus is usually in the form of a'hand tool which is rubbed or brushed against the surface to be plated. In the usual form, the tool has a terminal which is made anodic with respect to a workpiece for plating and cathodic for.electroetching or electrocleaning. The terminal is wrapped in a porous, dielectric fabric sock and rubbed over a surface while the sock is saturated with electrolyte. Brush plating techniques are described in U.S. Pat. Nos. 3,183,176; 3,313,715; and 3,393,134, all issued to B. A. Schwartz, Jr.

While brush plating has been successful in many applications, it has been restricted to relatively low rates of metal deposition due to the inability of conventional brush plating apparatus to operate at high current densities. For instance, a standard copper plating solution plates well with the brush plating technique when the brush tool is in a circuit of about 4 volts and amperes. However, as the voltage is raised to about 7.5 to 10 volts and the amperage to about amperes, there is considerable burning, and deposition of amorphous copper rather than copper plating. Similar difficulties are. encountered with other metals.

In U.S. patent application Sen-No. 152,802, filed in the names of Andrew J. Macula, John T. Macula and Benno A Schwartz, Jr. on June 14, 1971, entitled Brush Electroplating Metal at Increased Rates of Deposition, a vibrating brush plating. apparatus is disclosed and claimed which is capable of increased rates of metal deposition as compared to prior brush applicators. The apparatus of the application has a dielectric cover fitted about a plating terminal. In use the plating terminal is vigorously vibrated so that the cover slips relatively to the terminal. This results in a rubbing action by the cover against the terminal and the work and contributes to increased rates of metal deposition. However, there is no positive movement of the cover,

the movement of it being secondarily caused by the SUMMARY OF THE INVENTION It is, therefore, a general object of the present invention to provide an improved vibratory brush electroplating apparatus and a method of using it. Another object is the provision of such apparatus by which in- Briefly, these and other objects-of the invention are obtained by supporting a porous dielectric cover separately from the plating terminal but in contact with it, and directing a force positively to create relative movement between the cover and the terminal while maintaining the contacting relation. The motion of the dielectric cove'r relative to the terminal preferably takes place while the cover is in contact with both the elec trode-terminal of the apparatus, usually an anode, and the workpiece, usually a cathode, in order to provide a rubbing action on both electrodes. The speed at which the cover rubs the plating terminal is large as compared to the speed at which the entire electroplating apparatus moves with respect to the workpiece. The relative movement of the cover is in directions substantially parallel to the contacting surfaces of the terminal and the cover and may take any path of travel such as a closed circular or elliptical path or a reversible, linear movement. A rapid vibratory movement is preferred.

While the invention is not to be limited by theory, it is postulated that the increased rate of deposition obtained by the present invention results, at least in part, because of the movement of the cover with respect to the terminal with resultant scrubbing of both the terminal and the workpiece. The rubbing apparently disrupts the films that ordinarily form on the cathode and the anode, and removes unwanted products of electrolysis and insures the prompt removal of spent electrolyte from the terminal and from the surface to be plated.

In this manner, the rubbing at relatively high speed insures that electrolytic action takes place on surfaces that are maintained in a clean condition and substantially free from gas. In any event, the current density, and hence the rate of plating or other electrolytic action, can be increased as compared to conventional practices without undesirable effects.

BRIEF DESCRIPTION OF THE DRAWINGS Referring to the drawings:

FIG. I is a side elevational view, partially in section, of one embodiment of a brush electroplating apparatus made according to the present invention;

FIG. 2 is a bottom view of the apparatus of FIG. 1 with the dielectric cover and its clamp removed, the view being taken as indicated by line 22 of FIG. 1',

FIG. 3 is a vertical, longitudinal section of another embodiment of a brush electroplating apparatus made according to the present invention;

FIG. 41 is a top plan view of the apparatus of FIG. 3, the view being partially in section as indicated by line 4 4 of FIG. 3; and

FIG. 5 is a partial bottom view of the apparatus of FIG. 3 with the cover and its clamp removed, the view being taken as indicated by line 5-5 of FIG. 3.

DESCRIPTION OF THE PREFERRED EMBODIMENTS As noted above, in the present apparatus a dielectric cover, which is adapted to be saturated with electrolyte, is moved rapidly with respect to the electrode terminal when the apparatus is in use, and the cover is simultaneously moved over the workpiece. FIGS. 1 and 2 illustrate an embodiment in which the cover is moved in a closed or orbital path, while FIGS. 3 through 5 illustrate an embodiment in which the cover is reciprocated in a substantially linear path. Apparatus of the present invention may be used for electroetching and electrocleaning, in which case the terminal is the cathode and the workpiece the anode in the electrolyzing circuit. However, the apparatus is described herein primarily in connection with its usual application of electroplating, in which the terminal is the anode and the workpiece the cathode.

Referring to FIGS. 1 and 2, this embodiment comprises a hand tool generally indicated at and made up of a supporting portion comprising a hollow handle 11 and a hood 12 carried thereby. Parts that are electroconducting depend from the handle portion 11 and terminate in a circular plating terminal 13. Parts that are not electrically energized but are vibratory depend from hood l2 and include a porous dielectric cover 14 held against the bottom of a terminal 13 as described below.

The basic tool shown is of a known air-operated type used as a sander or the like. More particularly, the hollow handle 11 has conventional fittings 15 for connection to a suitable source of compressed air which conventionally rotates an air motor having an impeller (not shown) within hood 12. The impeller has a drive shaft 16 that imparts orbital movement to the terminal 13 as described below. Air supply to the air motor is controlled by a valve (not shown) operated by a cap 19 that is pivotally mounted on the housing 12 in a manner known in the art.

In order to'support the vibrating components of the tool, a tubular elastromeric boot 17 is suitably fixed at its upper end within hood 12 and engages an eccentric drive mechanism which in operation causes the lower end of boot 17 to travel in an orbital path. Boot 17 has a radially inturned flange 18 that engages a bearing block 20. Block 20 has a recess 21 to receive a pressfitted outer race of a ball bearing 22 having an inner race press-fitted to a stub shaft 23. Shaft 23 is eccentrically driven by shaft 16 through a projection 24 of reduced diameter that is secured in a socket in the lower face of a circular drive head 25. Head 25 has a socket in its upper face in which drive shaft 16 is secured by a set screw 26. The sockets in the driving head 25 are offset with respect to each other so that rotation of the shaft 16 causes the stub shaft 23 to travel in a circular orbit as it rotates, while the bearing block 20 moves in the same orbit but does not rotate.

In order to support the cover 14 and drive it in the desired orbital path, a hollow housing 28 depends from boot 17 and is held in place by bolts 29 which extend axially upwardly through openings 30 in housing 28 and engage threaded openings 31 in the underside of bearing block 20. Housing 28 is composed of insulating material and, like other non-conducting parts, may be made of rubber or suitable synthetic insulating materials. The upper portion of housing 28 has relatively thick walls 33 and a central open space 34 that communicates through a throat portion 35 with a radially enlarged recess 36 adapted to receive the plating terminal 13. The outer periphery of housing 28 is threaded as at 37 and carries an internally threaded locking ring 38 and a collar 39. The end face of collar 39 may be provided with a secondary plating terminal ring 40.

The dielectric porous cover 14 is secured across the open end of collar 39 by a resilient clamping band 41. Cover 14 may comprise a fabric, woven or unwoven, such as cotton, flannel, felt, canvas and the like. A preferred fabric for chromium plating is composed of polyester fibers, since these materials have good resistance to attack by chromic acid. By turning the collar 39 on the threaded portion 37 of housing 28, the level of the cover 14 can be adjusted with respect to the terminal 13, preferably so that the upper surface of the cover and the end of the collar lie in the same plane as the bottom surface of the terminal 13.

In order to provide a support for the terminal 13 and the conduits that supply electrolyte to the working face of the cover 14, a block 43 of insulating material is mounted on the tool portion 10 between hollow handle 11 and hood 12 by a bolt 44. Block 43 also provides support for the conductors that supply current to the terminal 13 and the ring terminal 40. A bolt 45 clamps a terminal 46 of an electric cable 47 to a lug 48 of a flat-sided, T-shaped metal block 50 (see FIG. 2). The stem 51 of the block 50 is drilled to form a bore 57, and a male fitting 55 and connecting hose 56 supply electrolyte from a suitable supply such as a pump (not shown) to the passage. The stem projects through an oval opening 58 in housing 28, the opening being large enough to permit the housing to move in its orbit without contacting the stem. The stem 51 terminates within open area 34. The terminal 13 is supported from the block and supplied with electrolyte and electric current by a tubular metal conduit 60 having an externally threaded end 61 that is screwed into an internally threaded transverse opening 62 adjacent the end of the stem of block 50 and is held in place by set screw 63. The interior of conduit 60 communicates with bore 57 of stem 51.

Conduit 60 passes through throat area 35 into recess 36 and is screwed into a central threaded opening 64 in the circular plating terminal 13. A cross-strip 65 screwed onto the threaded end of conduit 60 ahead of terminal 13 is secured to the terminal by bolts 66 to reinforce the union of conduit 60 and terminal 13. Plating terminal 13 has additional transverse openings 67 which facilitate circulation of electrolyte between the pad 14 and the reservoir provided by recess 36 and collar 39. In use, the presence of electrolyte in the reservoir insures an adequate supply of electrolyte to the entire area of the pad. Also, the electrolyte is quite violently agitated by the movement of the collar. In order to prevent electrolyte from passing upwardly through throat area 35, an elastomeric circular seal 68 encircles conduit 60 and has a circular rim 67 fitted into a matching recess in the bottom face of housing 28. A nut 71 holds seal 68 in place.

Electric current is supplied to the auxiliary electrode 40 by a conductor 54 that is secured to the block 50 and is clamped in engagement with the ring 40 by the clamping ring 41.

In operation electrolyte flows through passage 57 of T-block 50 and through conduit 60 to reach the terminal 13 and porous covering 14. The flow is controlled to keep a reservoir of electrolyte in recess 36, while the electrolyte passes through cover 14 onto a workpiece W during an electroplating operation. The electrolyte can be collected in a sump and recirculated if desired. Cable 47, lug 48, T-block 50 and conduit 60 supply current to plating terminal 13 by the same route, while extension cable 54 supplies current to ring terminal 40. The circuit is completed by another conductor 49 extending from the source of current, such as a rectifier, to the workpiece and held there by clamp 59.

The operator depresses cap 19 to open the valve that controls the flow of air to the air motor, thereby causing shaft 16 to rotate, resulting in an orbital movement of the bearing block 30, which is held against rotation about its own axis by the boot 17. The orbital movement of block 20 is transmitted through the housing 28 and collar 39 to the cover 14, while the plating terminal, being supported by the member 50, remains relatively stationary. This results in a rubbing action of cover 14 against terminal 13 and, when the cover is ap plied to a workpiece, against the workpiece as well.

Shaft 16 may be driven from about 700 revolutions per minute to about 2,000 revolutions per minute, for

example, depending on the size and/or contour of a workpiece. The operator moves the entire tool relatively slowly over the surface to be plated, for example, from'about 3inches to 12 inches per second. Electrolyte may be pumped at rates, for example, from l2 to gallons per hour with a tool having a round anode 13 2% inches in diameter and a collar 39 and pad 14 about 4 inchesin diameter. The movement of the cover is represented by lines 72 in FIG. 2, and in the example given the cover 14 was moved in an orbit having a radius equal to the radius of the cover plus about'l/4 inch; l

During electroplating, the ring terminal 40, which moves with respect to plating terminal 13 like cover 14, serves to make the current density more uniform over the entire surface of cover 14 that is in contact with the work. Ring terminal also assists in plating in confined areas since -the electroplatingoperation can be extended at least to the periphery of the collar.

Referring to FIGS. 3 through 5, this embodiment provides for reciprocal linear movement of a dielectric cover generally represented at 74 with respect to a plating terminal 75; A cylindrical handle generally indicated at 76, adapted to be held by an operator, supports the apparatus and contains means for vibrating cover 74 with respect to the terminal 75. The terminal 75 is supported and supplied with electrolyte and electric current through a tubular supporting conduit'77, the lower end'of which is screwed into a supporting plate 78 that-is secured to the terminal 75 by cap screws 79. The conduit 77 passes through an opening in the enlarged end portion of a supporting arm 81, and the conduit is securedin the desired position of vertical adjustment by means of a set screw 82. Electrolyte is supplied to the interior of the conduit 77 andto the terminal 75 through a'suitable flexible conduit 83 that leads from a pump or other supply of electrolyte, conduit 83 being connected to the conduit77 by an insulated fitting 84.

The support ai'rn'8lis slidab'ly carried by a conduc tive bushing 86'mounted'in anon-conductive block 87.

Block 87 is bonded to theplastic housing member 88 which is securedto the cylindrical handle member 76, as by a clamp 89. After arm 81 is slidably positioned in the bushing 86 as desired, set screw 85 holds it in place.

Asin the case of the previous modification, the cover 75 is vibrated" rapidly with respect to the terminal 75. This is accomplished by mounting the cover 74 on a collar 91 to which the cover is secured as by a clamping band 92. The collar and the bottom surface of the band are oval, as shown in FIGS. 4 and 5, and the collar is vibrated and supported by a bracket built up of

members

93 and 94 bolted respectively to the collar 91 and erator through lever 99, and appropriate passages in the block 101. In a typical embodiment the ram has a stroke of about 1/4 inch and operates about 2,800 complete reciprocations or cycles per minute. The rate can be varied by controlling the air supply. The ram slides in the supporting housing 88 and is prevented from rotation by a spring-pressed detent 103 that rides in an axially extending groove 104 in the ram.

The collar 91, like collar 39, provides a reservoir for electrolyte, the top of the collar being closed by an insulating cover 1016 secured to theconduit 77 by a set screw 107, the under surface of the cover being provided with a gasket 108 and the top edge of the collar 91 sliding on the under side of the gasket 108' during reciprocation. 7

Current for the electrolytic operation is supplied through a cable 109 that is secured to the nonconductive block 87 by a cap screw 90 and flows through the cap screw 90, the bushing 86, supporting arm 81 and tubular conduit 77 to the terminal 75. The connection of opposite polarity is made through the workpiece in the usual manner as illustrated in FIG. 1. Current is also supplied from an auxiliary cable 110, held by cap screw 90 to cable 109 against block 87, to a ring terminal 111 that is mounted in the lower edge of the collar 91 and is similar to'and provided for the 99 and moves-the pad slowly over the work to be treated at speeds comparable to those mentioned in connection with FIGS. 1 and 2. During this movement of the tool by the operator, the pad is vibrated rapidly in directions parallel to the face ofthe terminal and rubs rapidly against both the terminal and the work. Also, 'the'electrolyte is agitated quite 'violently within the reservoir provided by the collar 91. I

The pad 74'may be constructedofa single layer of material as previously describedflor, if desired, pad 74 may comprise layers such as are shown in somewhat exaggerated fashion in FIG. 3. For example, an inner layer 115 may be composed of felt, and an outer layer 116 may be composed of a plastic base material such as the material sold under the trademark SCOTCH BRITE, which is marketed by the Minnesota Mining and Manufacturing Company. Ifdesired, a material such as SCOTCH BRITE may be impregnated with a very. finely divided abrasive material such as aluminum oxide or, preferablydsilicone carbide may be employed. An intermediate padding layer 117 may also be employed to soften the pad and give it greater'ability to conform to irregularities in the surfacebeing plated or otherwise being electrolytically treated. Pads of the type justdescribedmay also be used with'the modifica- H tion shown in FIGS. 1 and '2. Clamping band 92 may ex the-mechanism from any suitable source through con- I duit 97, valve 98, which is. under the control ofthe optend around all the layers of pad'74, 116 and 117, or an additional band 118 may be used for the outer two layers.

The form of the invention shown in FIGS. 3, 4 and 5 is adapted for use in areas that might not be conver iently accessible to an apparatus such'as shown in FIGS. 1 and 2. By increasing the lengths of the supporting bar 81 and the ram 95 as well as the lengths of the flexible conduits and cables, the terminal 75 and pad 74 and associated mechanisms can be disposed a greater distance from the handle 76 of the tool, thus making it possible to utilize the tool in locations that might otherwise be inaccessible. Also, the oval shape is more adapted to some kind of work than the round shape of the embodiment shown in FIGS. 1 and 2. In a typical tool of the type shown in FIGS. 3, 4 and 5, the terminal 75 may be 1% inches wide and 3% inches long, and the collar 91 may be an oval of corresponding shape about 3 inches wide by 5% inches long.

Electrolytes do not form part of the present invention. The method and apparatus of the invention can be used with conventional electrolytes used with brush plating apparatus for cleaning, activating, stripping and electroplating. Any metal that can be deposited by brush plating operations can be deposited by the present apparatus and method. For plating operations, the electrode-terminal is the anode and may be either soluble or insoluble. If soluble anodes are employed, they are composed of the metal that is being electroplated. Insoluble anodes may be composed of material such as lead or titanium or tantalum plated with platinum or rhodium.

ln general it may be said that electrolytic operations can be carried out much more rapidly with the present apparatus and method than with conventional brush plating tools. Heating of the anode is reduced and higher than usual current densities can be employed for plating operations with the result that less time is required to deposit a given thickness of metal and yet the quality of the deposits and the adherence to underlying surfaces are excellent.

Although the foregoing describes presently preferred embodiments of the invention, it is understood that the invention may be practiced in still other forms within the scope of the following claims.

What is claimed is:

1. Brush electroplating apparatus comprising a hand tool having a supporting portion having a handle portion adapted to be grasped by an operator, a plating terminal fixed with respect to said supporting portion, an insulating housing supported by the supporting portion for movement with respect thereto and carrying a porous dielectric cover disposed in contacting relation with said terminal and adapted to be brushed against a workpiece to be plated, means comprising a conduit carried by said supporting portion for supplying electrolyte to said terminal and cover, means for supplying electric current to said terminal, and power means carried by said supporting portion for vibrating said housing to move said cover with respect to said terminal while maintaining said contacting relation therebetween.

2. The brush electroplating apparatus of claim 1 in which said means for supplying electrolyte to said terminal supports the terminal in fixed relation to said tool.

3. The brush electroplating apparatus of claim 1 in which said housing has a recess at its free end adapted to receive said plating terminal, and said means for supplying electrolyte to said terminal and porous cover includes a conduit adapted to carry electrolyte extending longitudinally of the housing into said recess and fixed to and supporting said plating terminal therein.

4. The brush electroplating apparatus of claim 1 in which said housing is flexibly carried by said tool for movement laterally thereof, and said vibratory power means comprises an eccentric drive arrangement for moving said housing and cover in a closed path.

5. The brush electroplating apparatus of claim 1 in which said vibratory power means comprises pneumatic means for reciprocating said housing and cover in a substantially linear path.

6. The brush electroplating apparatus of claim 1 in which said housing has a stretchable, elastomeric boot member interconnecting said tool and housing to enable movement of the housing laterally of the tool.

7. The brush electroplating apparatus of claim 1 in which said mounting terminates in a collar member disposed about the terminal and carrying said porous dielectric cover.

.8. The brush electroplating apparatus of claim 7 in which said collar is non-electroconducting and adapted for axial adjustment with respect to said housing.

9. The brush electroplating apparatus of claim 7 in which said collar is non-electroconducting and contains a second plating terminal in contacting relation with said porous cover.

10. The brush electroplating apparatus of claim 1 in which said plating terminal has a fixed but adjustable position with respect to said tool portion.

11. In brush electrolytic apparatus of the character described, the improvements comprising a hand tool having a supporting portion having a handle portion adapted to be grasped by an operator, a terminal fixedly supported by the supporting portion, a collar member carried by the tool surrounding the terminal and having a dielectric cover contacting the terminal, means for supplying electric current to the terminal, means for supplying electrolyte to the terminal, and means carried by the supporting portion for vibrating the collar and cover with respect to said terminal and the supporting portion.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent 92 7 Dated December 18, 1973 Inventor(s) Anthony Gildone It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Claim 7, 'line 2 (Column 8, line 28) "mounting" should 7 read --housing-.

Signed and sealed this 9th day of April, 197R.

(SEAL) Attest':

EDWARD M.FLETCHER,JR. C. MARSHALL DANN Attesting Officer- Commissioner of Patents USCOMM-DC GO376'P69 w us. GOVERNMENT PRINTING OFFICE: I959 0-366-334 F OHM PC4050 (10-69)

Claims

2. The brush electroplating apparatus of claim 1 in which said means for supplying electrolyte to said terminal supports the terminal in fixed relation to said tool.
3. The brush electroplating apparatus of claim 1 in which said housing has a recess at its free end adapted to receive said plating terminal, and said means for supplying electrolyte to said terminal and porous cover includes a conduit adapted to carry electrolyte extending longitudinally of the housing into said recess and fixed to and supporting said plating terminal therein.
4. The brush electroplating apparatus of claim 1 in which said housing is flexibly carried by said tool for movement laterally thereof, and said vibratory power means comprises an eccentric drive arrangement for moving said housing and cover in a closed path.
5. The brush electroplating apparatus of claim 1 in which said vibratory power means comprises pneumatic means for reciprocating said housing and cover in a substantially linear path.
6. The brush electroplating apparatus of claim 1 in which said housing has a stretchable, elastomeric boot member interconnecting said tool and housing to enable movement of the housing laterally of the tool.
7. The brush electroplating apparatus of claim 1 in which said mounting terminates in a collar member disposed about the terminal and carrying said porous dielectric cover.
8. The brush electroplating apparatus of claim 7 in which said collar is non-electroconducting and adapted for axial adjustment with respect to said housing.
9. The brush electroplating apparatus of claim 7 in which said collar is non-electroconducting and contains a second plating terminal in contacting relation with said porous cover.
10. The brush electroplating apparatus of claim 1 in which said plating terminal has a fixed but adjustable position with respect to said tool portion.
11. In brush electrolytic apparatus of the character described, the improvements comprising a hand tool having a supporting portion having a handle portion adapted to be grasped by an operator, a terminal fixedly supported by the supporting portion, a collar member carried by the tool surrounding the terminal and having a dielectric cover contacting the terminal, means for supplying electric current to the terminal, means for supplying electrolyte to the terminal, and means carried by the supporting portion for vibrating the collar and cover with respect to said terminal and the supporting portion.