US3886343A

US3886343A - Polyphase arc stripper

Info

Publication number: US3886343A
Application number: US407007A
Authority: US
Inventors: Paul M Desautels; Lawrence P Remsen
Original assignee: International Business Machines Corp
Current assignee: International Business Machines Corp
Priority date: 1973-10-17
Filing date: 1973-10-17
Publication date: 1975-05-27
Anticipated expiration: 1992-05-27
Also published as: ES431123A1; AU7447774A; CS180028B2

Abstract

An improved arc stripper for stripping insulation from an electrical wire is provided with three electrodes that are positioned symetrically about a point where the wire is to be stripped. The three electrodes are excited from a three phase power supply and produce an arc that is readily maintained in a position to strip insulation from the wire.

Description

United States Patent [191 Desautels et al.

[ 1 POLYPHASE ARC STRIPPER [75] Inventors: Paul M. Desautels, Poughkeepsie;

Lawrence P. Remsen, Stanfordville,

both of NY.

[73] Assignee: IBM Corporation, Armonk, NY.

[22] Filed: Oct. 17, 1973 [21] Appl. No.: 407,007

[52] U.S. Cl. 219/68; 219/122; 219/383 [51] Int. Cl 823p 1/02 [58] Field of Search 219/68, 85, 122, 123, 243,

[56] References Cited UNITED STATES PATENTS 11/1966 De Bolt 219/123 X [451 May 27, 1915 3,505,916 4/1970 Brandt 219/68 X 3,646,307 2/1972 Hazel 219/85 X Primary Examiner.l. V. Truhe Assistant ExaminerN. D. Herkamp Attorney, Agent, or FirmW. S. Robertson [57] ABSTRACT An improved arc stripper for stripping insulation from an electrical wire is provided with three electrodes that are positioned symetrically about a point where the wire is to be stripped. The three electrodes are excited from a three phase power supply and produce an are that is readily maintained in a position to strip insulation from the wire.

7 Claims, 7 Drawing Figures Pmmwwm ms 3.886343 SHEET 2 FIG.3

POLYPHASE ARC STRIPPER RELATED APPLICATIONS US. Pat. No. 3,646,307 issued to H. Kenneth Hazel supplements the description in this specification by showing an arc stripper and an apparatus for bonding a wire from which insulation has been stripped.

INTRODUCTION Stripping insulation from an electrical wire is a familiar operation in manufacturing electrical apparatus. Commonly, the insulated wire is gripped by hand or by a mechanical tool and the insulation is cut away from the wire at the point where the wire is to make electrical contact. There are limitations to these methods when stripping very small wires that are used for making connections between integrated circuit components. It has also been proposed to strip wires by striking an electric arc in the region of the wire to remove the insulation by means of the arc. The cited patent shows one are stripper, and generally similar arc strippers have been described in the IBM Technical Disclosure Bulletin: Wire Stripper by L. M. Lancaster, Vol. 10,No. 4, September 1967; Electric Arc Stripper by E. H. Empson, Vol. 12, No. 8, Jan. I970; and High- Energy Arc Wire Insulation Removal Tool by P. M. Desautels and H. C. Schick, Vol. 13, No. 12, May 1971.

As these designs for are strippers show, there has been substantial interest in developing an arc stripper, but shortcomings have been found in these designs and none of these developments have proceeded beyond laboratory experiments.

In an arc stripper, a high voltage between a pair of electrodes establishes a conductive path through the normally non-conducting air in the neighborhood of the wire that is to be stripped. Positive ions and free electrons in the air provide the charge carriers. The high temperature of the arc maintains these charge carriers and the are thus tends to avoid a path containing a cooling element such as the walls of the supporting structure or the wire that is to be stripped. Accordingly, it has been difficult in known are strippers to maintain the arc in a position to strip the insulation; an object of this invention is to provide a new and improved arc stripper that overcomes this problem.

SUMMARY OF THE INVENTION In the specific embodiment of the invention that will be described later, three electrodes are located symetrically about the position where an insulated wire is to be stripped, and the electrodes are energized from a three phase power supply. An arc is produced between pairs of electrodes in a three phase sequence. The arc has been observed to occur substantially equally along each of the three paths in close contact with the insulation and thereby to suitably strip the insulation.

From a more general standpoint, a plurality of electrodes are positioned about a point where a wire is to be located and periodic voltages are applied between pairs of electrodes that establish a well defined arc path over a surface of the wire insulation (rather than through the wire itself or along alternative paths on either side of the wire and insulation). This are stripper establishes arc paths over a short circumference of the wire and thus does not permit alternate paths on either side of the wire, and it energizes the electrodes periodically to further assure that the arc forms along each of these paths.

The following description of the preferred embodiment of the invention will suggest to those skilled in the art various other features and advantages of this invention.

THE DRAWING FIG. I is a simplified isometric view of the preferred are stripper.

FIG. 2 shows a wire from which a region of insulation has been stripped.

FIG. 3 is a side view partially in section of the preferred arc stripper.

FIG. 4 is an enlarged view of a section of FIG. 3 showing the electrode structure.

FIGS. 5, 6, and 7 are simplified views similar to FIG. 4 showing a sequence of steps in a stripping operation.

THE PREFERRED EMBODIMENT OF THE INVENTION Introduction The general features of the preferred are stripper can be understood from the simplified isometric drawing of FIG. I. A housing 12 is made ofa suitable arc resistant material such as any suitable ceramic. At its forward end, the housing has a slot 14 that receives a wire 15 from which the insulation I6 is to be stripped. As the drawing illustrates, the wire is advanced from the stripper with a previously stripped portion in a position for a subsequent operation such as bonding. The cited patent to H. Kenneth Hazel illustrates the combination of a wire bonder and an arc stripper and will suggest applications of this are stripper to various analogous operations. As FIG. 2 shows, the arc stripper strips the wire 15 clear along a selected length and bevels the insulation on either side of the stripped portion. With beveled insulation at the point of stripping, the wire can be more easily positioned at a point where the bonding operation is to take place. Stripping operations of only a few mills have been made. Longer lengths can be stripped by increasing the time that the arc is on, by increasing the voltage, and by repetitive stripping operations.

The rear position of housing 12 has a flange l8 and three electrical connectors 19, 20 (and 21 not shown) and associated bushings (22 not shown), 23 and 24. As will be explained later, the connectors are attached to conductors that lead to the arc forming components in the region of the forward end of slot 14. In a typical arc stripper the housing 12 is about an inch in length, counting flange 18 but not counting the bushings. The bushings and connectors plug into an electrical receptacle that provides mechanical support as well as electrical contact.

The arc stripper is energized from a three phase power supply that has means for independently adjusting the voltage of each phase and has means for timing the duration of an are. A suitable maximum voltage is about 7,500 volts. A typical operating voltage is about I,SO0 volts, an advantageously low value. These components are commercially available and are represented schematically in FIG. 1 by a block 25 and

electrical lines

26, 27 and 28. The connections to the arc stripper are of course suitably insulated and personnel operating or maintaining the arc stripper are suitably protected.

The Arc Forming Components FlGS. 3, 4 and 5 The general features that have been described so far will be readily apparent in the sectional side view of HQ. 2 which additionally shows a conductor 30 associated with bushing 23 and connector in MG. 1. Conductor and two similar conductors 31, 32 are shown in FIG. 4.

Conductors

30, 31, 32 are arranged substantially symetrically about a point 35 in slot 14 where a wire that is to be stripped is to be located. In the preferred embodiment of the invention, the

wires

30, 31, and 32 are given a square cut end as shown in H6. 3 to have a sharp edge for better initiating an arc. The conductors are made of a suitable arc withstanding ma-- terial such as molybdenum. and housing 12 is formed with holes for receiving the conductors.

Small holes

37, 38. 39 provide an arc path between the electrodes and an are receiving space formed by slot 14. We have found that the diameter of these holes should be about twice the diameter of the wire that is to be stripped. Thus, a wire of 1 mil diameter with a l mil radius of insulation has a 3 mil diameter, and holes 37, 38, 39 are preferably 6 mils in diameter. As HGS. 2 and 3 show, the arc holes and holes for the conduc tors and electrodes are preferably formed from one outer surface of housing 12 to another and are closed at one end by plugs 41. -12.

Thus, in the region of

holes

37, 38 and 39, conductors 3U, 31 and 32 form electrodes and elsewhere they form means to carry current to the electrodes. (An alternate embodiment of the invention. that will be de scribed later has distinct electrodes and current carrying conductors.)

Operation FIGS. 5. 6 and 7) FIGS. 5, 6, and 7 are each a simplified view of FIG. 3 showing the electrodes and the arc in relation to an insulated wire l5, 16 that is to be stripped. As these fig ures represent, an are normally forms only between two electrodes. The polyphasc excitation of the electrodes causes the arc to move around the wire in a way that is analogous to the rotating motion of a magnetic field in a polyphase motor. In the sequence of FIGS. 5, 6 and 7, the arc rotates clockwise. Notice that each arc path is to one side of the wire, Thus, the arc is readily main tained in a position to strip the insulation 16 from wire 15.

OTHER EMBODIMENTS OF THE INVENTION The operating principles of the preferred embodiment of the invention can be achieved in various structures. For example, the slot 14 is preferred for most wire stripping and subsequent operations, but alternatively a hole can be provided in housing l2 and the insulated wire can he threaded through the hole. The structure shown in the sectional view of PK] 4 can be formed by two ceramic plates, one of which is flat and one oi which has grooves that establish the holes for the electrodes and holes 37, 38. 39 for the are when the two plates are lit togetherv In this embodiment, the electrodes are preferably formed of flat. pointed, conductors that are connected to electrical wires that sup ply electrical power.

The arts of manufacturing arc producing structures are well developed and those skilled in the art will recognize many variations in the disclosed embodiments of the invention within the spirit. of the invention and the scope of the claims.

What is claimed is:

1. Apparatus for stripping insulation from a wire comprising,

at least three electrodes,

insulating means of supporting said electrodes about a point midway between said electrodes and rneans for locating a wire to be stripped at said point,

a polyphase power supply connected to said electrodes to produce arcs between pairs of electrodes in a rotating sequence for stripping insulation from a wire.

2. The apparatus of Claim 1 wherein said insulating means has a slot for receiving a wire at said point and the walls ol said slot are shaped to locate the wire at said point 3. The apparatus of claim 2 wherein said electrodes are positioned about said point in a plane that is sub stantially orthogonal to the path ol a wire to be stripped and are spaced apart by about 4. Apparatus for stripping insulation from a wire comprising.

at least three electrodes,

electrode supporting means having a wire receiving space, means for supporting said electrodes about a point in said space midway between said electrodes, means for locating a wire at said point, and having arc transmitting holes between said electrodes and the wire receiving space,

a polyphase power supply connected to said electrodes to produce arcs between pairs of electrodes in a rotating sequence for stripping insulation from a wire at said point,

5. The apparatus of claim 4 wherein the diameter of said are transmitting holes is substantially twice the diameter of the wire that is to be stripped.

6. The apparatus of claim 4 wherein said apparatus has three electrodes and said power supply has three phases.

7. The apparatus of claim 6 wherein said power supply is adjustable in voltage for each phase and includes means for timing an are that is applied to strip a wire.

Claims

1. Apparatus for stripping insulation from a wire comprising, at least three electrodes, insulating means of supporting said electrodes about a point midway between said electrodes and means for locating a wire to be stripped at said point, a polyphase power supply connected to said electrodes to produce arcs between pairs of electrodes in a rotating sequence for stripping insulation from a wire.

2. The apparatus of claim 1 wherein said insulating means has a slot for receiving a wire at said point and the walls of said slot are shaped to locate the wire at said point.

3. The apparatus of claim 2 wherein said electrodes are positioned about said point in a plane that is substantially orthogonal to the path of a wire to be stripped and are spaced apart by about 120*.

4. Apparatus for stripping insulation from a wire comprising, at least three electrodes, electrode supporting means having a wire receiving space, means for supporting said electrodes about a point in said space midway between said electrodes, means for locating a wire at said point, and having arc transmitting holes between said electrodes and the wire receiving space, a polyphase power supply connected to said electroDes to produce arcs between pairs of electrodes in a rotating sequence for stripping insulation from a wire at said point.

5. The apparatus of claim 4 wherein the diameter of said arc transmitting holes is substantially twice the diameter of the wire that is to be stripped.

7. The apparatus of claim 6 wherein said power supply is adjustable in voltage for each phase and includes means for timing an arc that is applied to strip a wire.