Welding by high frequency current penetration

Claim 3

A method according to claim 1 wherein said contacts engage a surface of a portion opposite from said contacting surfaces and said reference depth is greater than the thickness of said last-mentioned portion whereby said current is caused to flow through the thickness of said last-mentioned portion.

Claim 4

A method according to claim 1 further comprising confining and increasing the concentration of the current at said surfaces by disposing magnetic elements adjacent tone of said portions with said elements extending longitudinally of said line but in spaced-apart relation on spaced-apart sides of said line.

Claim 5

A method according to claim 1 wherein said portions are parts of an interlocking seam and said current flows at least in a pair of the adjacent parts thereof.

Claim 6

A method according to claim 1 wherein said portions are parts of an interlocking seam having at least four layers of metal and wherein the frequency of said current is such that the reference depth thereof is greater than the thickness of two of said layers.

Claim 7

A method according to claim 1 further comprising rapidly advancing said portions in the direction extending from one contact toward the other while said current is flowing therein.

Claim 8

A method according to claim 1 further comprising rapidly advancing said portions in a direction transverse to at least a portion of said line.

Claim 9

A method according to claim 1 further comprising causing said contacts and said portions to move relative to each other while said current is flowing in said portions.

Claim 10

A method according to claim 8 further comprising intermittently supplying said current to said contacts whereby a succession of spaced-apart line welds are formed between said portions.

Claim 11

A method according to claim 1 wherein said portions are portions respectively of inner and outer walls of multiwall tubing and wherein said line extends both longitudinally and circumferentially of said tubing whereby a line weld is produced between the inner surface of said outer wall and the outer surface of said inner wall.

Claim 12

A method according to claim 1 wherein said line, and also said path, each has portions extending transversely to other portions thereof, and rapidly advancing said metal portions in the direction of at least one portion of said line and transverse to at least one other portion of said line while current is flowing in said metal portions.

Claim 13

A method according to claim 1 wherein said path is curved whereby said surfaces are heated to welding temperature along a curved line corresponding in shape to the curvature of said path.

Claim 16

Method of welding together the facing surfaces of a pair of overlapping metal portions along a line which comprises maintaining said portions in overlapping conductive contact at the ends of the desired line of weld, supplying high frequency current to said portions at points adjacent said ends and which are in fixed relation thereto and provide current flows in the same direction along both said portions and at said line, conducting said current in the opposite direction along a proximity conductor extending along said line and in close proximity to but insulated from said portions, said current having a frequency which provides a reference depth greater than the thickness of the metal of the one of said portions which is intermediate said proximity conductor and the other of said portions and which provides heating of the metal along said line to the desired welding temperature without overheating of the metal at the ends of said line, maintaining such flow of current with a magnitude and for the time required to heat said portions along and throughout the length of said line to the desired welding temperature without overheating of the metal at the ends of said line and applying pressure to the heated said portions along the length of said line to forge weld them together along said line.

Claim 17

Method of welding together the facing surfaces of a pair of overlapping metal portions along a line which comprises maintaining said portions in overlapping conductive contact at the ends of the desired line of weld, supplying high frequency current to said portions at points adjacent said ends and which are in fixed relation thereto and provide current flows in the same direction along both said portions and at said line, conducting said current in the opposite direction along a proximity conductor extending along said line and in close proximity to but insulated from said portions, said current having a frequency which provides a reference depth greater than the thickness of the metal of the one of said portions which is intermediate said proximity conductor and the other of said portions and which provides heating of the metal along said line to the desired welding temperature without overheating of the metal at the ends of said line, maintaining such flow of current with a magnitude and for the time required to heat said portions along and throughout the length of said line to the desired welding temperature without overheating of the metal at the ends of said line and applying pressure to the heated said portions along the length of said line to forge weld them together along said line.

Claim 18

Method according to claim 14 in which said current has a frequency which provides a reference depth greater than the thickness of the metal portion nearer said proximity conductor.

Claim 19

Method according to claim 15 in which said current has a frequency which provides a reference depth less than the combined thicknesses of said metal portions.

Claim 20

Method according to claim 14 in which said pair of overlapping metal portions also overlaps at least one other metal portion and said other metal portion is maintained in contact with at least one of said pair of metal portions at least at said ends and in which said current has a frequency which provides a reference depth greater than the combined thicknesses of said pair of metal portions.

Claim 21

Method according to claim 14 in which the pressure applied to the heated portions is sufficient to reduce the thickness thereof to less than the combined thicknesses of said metal portions.

Claim 22

Method according to claim 18 in which said pressure is sufficient to reduce the thickness of the heated portions to a thickness substantially equal to the thickness of one of said metal portions.

Claim 23

Method according to claim 14 in which said overlapping metal portions are the opposite edge portions of a single strip.

Claim 24

Method according to claim 20 in which said opposite edge portions are mechanically interlocked.

Claim 25

Method according to claim 14 in which one of said metal portions is the side surface of a metal strip and the other portion is the edge surface of a metal strip.

Claim 26

Method according to claim 14 in which the metal portions are oppositely extending edge portions of metal strip and said proximity conductor is disposed to one side of the edge of one of said portions and in a position in which said last-mentioned one portion does not intervene between said proximity conductor and the other of said portions.

Claim 27

Method according to claim 14 in which said current is also conducted in said opposite direction along a second proximity conductor spaced from the firsT-mentioned proximity conductor and extending along said line and in close proximity to but insulated from said portions.

Claim 28

Method according to claim 14 wherein said portions are pressed together in the same position as that in which they are heated.

Claim 29

Method according to claim 14 wherein pressure is applied to said portions along the length of said line during the flow of current therein.

Claim 30

Method according to claim 14 wherein when said portions are heated to welding pressure, they are moved to a forging position different from the position in which current is supplied thereto and said pressure is applied to the heated said portions in said forging position.

Claim 31

Method according to claim 14 wherein said portions have a length which is the same as the length of said line.

Claim 32

Method according to claim 14 wherein said portions are longer than said line.

Claim 33

Method according to claim 14 wherein said current is supplied to a pair of points adjacent each of said ends, each of said pair of points being disposed on opposite sides of said line.

Claim 34

Method according to claim 30 wherein one of said pair of points is on a surface of one of said metal portions and the other of said pair of points is on a surface of the other of said metal portions.

Claim 35

Method according to claim 14 wherein said points are on the surface of the metal portion more remote from said proximity conductor than the other metal portion and said surface is other than a surface between said metal portions.

Claim 36

Method according to claim 14 wherein said points are on the same surface of one of said metal portions.

Claim 37

Apparatus for producing a line weld between a pair of overlapping metal portions comprising contact means for providing a first electrically conductive connection with one of said portions adjacent one end of said line and a second electrically conductive connection with one of said portions adjacent the opposite end of said line, means for maintaining said portions in conductive contact at least at said one and said opposite ends, a proximity conductor having an electrically conductive connection at one end thereof with said first connection and mounted to extend from adjacent said one end of said line along said line and in close proximity but in insulated relation to said portions to adjacent said opposite end of said line, means for connecting said contact means for providing said second connection to one terminal of a high frequency source providing current of a frequency such that the reference depth thereof is greater than the thickness of the metal intermediate said proximity conductor and the metal portion more remote from said proximity conductor and such that the metal along said line will reach welding temperature without overheating at the contact points, means for connecting a different terminal of said source to said proximity conductor so as to provide current flow therein opposite in direction to the current flow in said portions, means for maintaining said portions in fixed relation to each other and to said contact means during current flow therein, and means for forging said portions together along the length of said line when said portions reach forging temperature along the length of said line.

Claim 38

Apparatus for producing a line weld between a pair of overlapping metal portions comprising contact means for providing a first electrically conductive connection with one of said portions adjacent one end of said line and a second electrically conductive connection with one of said portions adjacent the opposite end of said line, means for maintaining said portions in conductive contact at least at said one and said opposite ends, a proximity conductor having an electrically conductive connection at one end thereof with said first connection and mounted to extend from adjacent said one end of said line along said line and in close proximity but in insulated relation to said portions to adjacent said opposite end of said line, means for connecting said contact means for providing said second connection to one terminal of a high frequency source providing current of a frequency such that the reference depth thereof is greater than the thickness of the metal intermediate said proximity conductor and the metal portion more remote from said proximity conductor and such that the metal along said line will reach welding temperature without overheating at the contact points, means for connecting a different terminal of said source to said proximity conductor so as to provide current flow therein opposite in direction to the current flow in said portions, means for maintaining said portions in fixed relation to each other and to said contact means during current flow therein, and means for forging said portions together along the length of said line when said portions reach forging temperature along the length of said line.

Claim 39

Apparatus as set forth in claim 34 further comprising means for engaging said metal portions along the length of said line and for maintaining said portions under pressure for forging them together during the heating thereof.

Claim 40

Apparatus as set forth in claim 34 wherein said forging means is made of electrical insulating material and is engageable with said metal portion along said line during the heating thereof.

Claim 41

Apparatus as set forth in claim 36 wherein said forging means comprises means for applying forge welding pressure to said metal portions along said line during the heating thereof.

Claim 42

Apparatus as set forth in claim 34 wherein the spacing of said proximity conductor with respect to the metal portions varies in the direction of The length of said proximity conductor.

Claim 43

Apparatus as set forth in claim 34 wherein said proximity conductor is disposed so that the metal portion nearer thereto is to one side of a straight line extending from said proximity conductor to the other metal portion.

Claim 44

Apparatus as set forth in claim 34 further comprising a second proximity conductor connected in parallel with and extending similarly to said first-mentioned proximity conductor, said first-mentioned and second proximity conductors being disposed on opposite sides of said line.

Claim 45

Apparatus as set forth in claim 40 wherein said first-mentioned and second proximity conductors are also disposed at the same side of one of said portions.

Claim 46

Apparatus as set forth in claim 40 wherein said first-mentioned and second proximity conductors are also disposed at opposite sides of one of said portions.

Claim 47

Apparatus as set forth in claim 34 wherein the shape of said proximity conductor, and hence the area of the surface thereof nearest said metal portions, varies in the direction of the length of said proximity conductor.

Claim 48

Apparatus as set forth in claim 34 wherein said proximity conductor has a pair of spaced, longitudinally extending surfaces which are nearer to said metal portions than the remainder of the proximity conductor.

Claim 49

Apparatus as set forth in claim 34 further comprising a magnetic element extending at least partly around said proximity conductor and adjacent at least one of said metal portions but displaced to the side of said line.

Claim 50

Apparatus as set forth in claim 34 wherein said forging means comprises a forging bar of insulating material extending around said proximity conductor.

Claim 51

Apparatus as set forth in claim 34 wherein said contact means comprises a conductive member extending at least for the length of said line and conductively engageable with a surface of one of said metal portions at least adjacent said ends.

Claim 52

Apparatus as set forth in claim 47 wherein said member is engageable with a surface of the metal portion which is more remote from said proximity conductor, said last-mentioned surface also being the surface of said last-mentioned portion which is more remote from said proximity conductor and which underlies the overlapping metal portion which is nearer to said proximity conductor.

Claim 53

Apparatus as set forth in claim 47 wherein said member is engageable with a surface of the metal portion which is nearer said proximity conductor said last-mentioned surface also being the surface of said last-mentioned portion which is nearer said proximity conductor but is a portion thereof spaced to one side of said line.

Claim 54

Apparatus as set forth in claim 34 wherein said contact means comprises a pair of conductive members extending at least for the length of said line and conductively engageable with said portions at least adjacent said ends, said members being disposed on opposite sides of said line and one said member being engageable with a surface of one of the metal portions and the other said member being engageable with a surface of the other of said metal portions.

Claim 55

Apparatus as set forth in claim 50 wherein said members engage the surfaces of said metal portions which are nearer said proximity conductor and are each spaced from said proximity conductor by a distance at least five times the spacing between said proximity conductor and the surface of the metal portion nearer thereto.

Claim 56

Apparatus as set forth in claim 34 wherein said proximity conductor comprises a pair of parts, one of said parts also forming part of said means for connecting said contact means for providing said second connection to said one terminal.

Claim 57

High frequency welding apparatus for welding together edge portions of metal strip which are in overlapping relation, said strip having a finite, predetermined width and a predetermined thickness and the desired weld being between the overlapping portions and extending along a line substantially equal in lengTh to the width of said strip and said overlapping portions being in conductive contact at least at the ends of said line, said apparatus comprising contact means for providing a first contact conductively engaging said strip adjacent one of said ends and a second contact conductively engaging said strip adjacent the other of said ends, a proximity conductor extending along said line from one end to the other thereof and in close proximity but insulated relation to said portions, a source of current having a frequency such that the reference depth in the metal of said strip is greater than said thickness but such that the metal along said line will reach welding temperature without overheating the metal engaged by said contacts and at the points of contact between said portions, means connecting said proximity conductor and said first and second contacts to said source so that the current flow in said proximity conductor is opposite to the current flow in said portions, means for maintaining said portions in overlapping relation and in fixed relation to said first and second contacts during the flow of current therein, and forging means engageable with said portions for forging them together when forging temperature is reached along the length of said line.

Claim 58

High frequency welding apparatus for welding together edge portions of metal strip which are in overlapping relation, said strip having a finite, predetermined width and a predetermined thickness and the desired weld being between the overlapping portions and extending along a line substantially equal in lengTh to the width of said strip and said overlapping portions being in conductive contact at least at the ends of said line, said apparatus comprising contact means for providing a first contact conductively engaging said strip adjacent one of said ends and a second contact conductively engaging said strip adjacent the other of said ends, a proximity conductor extending along said line from one end to the other thereof and in close proximity but insulated relation to said portions, a source of current having a frequency such that the reference depth in the metal of said strip is greater than said thickness but such that the metal along said line will reach welding temperature without overheating the metal engaged by said contacts and at the points of contact between said portions, means connecting said proximity conductor and said first and second contacts to said source so that the current flow in said proximity conductor is opposite to the current flow in said portions, means for maintaining said portions in overlapping relation and in fixed relation to said first and second contacts during the flow of current therein, and forging means engageable with said portions for forging them together when forging temperature is reached along the length of said line.

Claim 59

Apparatus as set forth in claim 53 wherein said contact means comprises a conductive bar at least equal in length to the width of said strip and engaging the lowermost surface of the edge portion more remote from said proximity conductor.

Claim 60

Apparatus as set forth in claim 53 wherein said contact means comprises a conductive bar at least equal in length to the width of said strip and engaging the uppermost surface of said strip.

Claim 61

Apparatus as set forth in claim 53 wherein said contact means comprises a pair of spaced conductive bars each at least equal in length to the width of said strip and engaging the lowermost surface of said strip.

Claim 62

Apparatus as set forth in claim 53 wherein said contact means comprises a pair of spaced conductive bars each at least equal in length to the width of said strip and engaging the uppermost surface of said strip.

Claim 63

Apparatus as set forth in claim 57 wherein said bars are interconnected at both of their ends by respective conductive tiepieces and said proximity conductor is conductively secured at one end thereof to one of said tiepieces.

Claim 64

Apparatus as set forth in claim 53 wherein said contact means comprises a conductive anvil having a length at least equal to the width of said strip and engaging the lowermost surface of the metal portion which is more remote from said proximity conductor and said forging means comprises a bar having a length at least equal to the width of said strip and engaging the uppermost surface of the metal portion which is nearer said proximity conductor, and means for pressing said bar against said last-mentioned portion.

Claim 65

Apparatus as set forth in claim 59 wherein said bar is made of insulating material.

Claim 66

Apparatus as set forth in claim 59 wherein said bar is electrically insulated from said portions.

Claim 67

Apparatus as set forth in claim 53 wherein said forging means comprises a pair of rollers engageable with said portions, means for pressing said rollers toward each other and means for moving said portions between said rollers after they have reached welding temperature.

Claim 68

Apparatus as set forth in claim 53 wherein said forging means is displaced with respect to said proximity conductor and comprises an anvil and a forging bar for receiving said portions therebetween after they have been heated to welding temperature and means for forcing said bar against said portions.

Claim 69

High frequency welding apparatus for welding together edge portions of metal strip which are in overlapping relation, said strip having a finite, predetermined width and a predetermined thickness and the desired weld being between the overlapping portions and extending along a line substantially equal in length to the width of said strip and said overlapping portions being in conductive contact at least at the ends of said line, said apparatus comprising a conductive anvil for supporting said portions and engageable with the lowermost surface of the overlapped portions, a proximity conductor extending along said line from one end to the other thereof and in close proximity but insulated relation to said portions with said portions between said proximity conductor and said anvil, an insulating member extending between said proximity conductor and said portions, a source of current having a frequency such that the reference depth in the metal of said strip is greater than said thickness but such that the metal along said line will reach welding temperature without overheating the metal engaged at the points of contact between said portions, means conductively connecting one end of said anvil and one end of said proximity conductor together, means connecting the opposite ends of said anvil and said proximity conductor to said source and means for pressing said insulating member against said portions.

Claim 70

High frequency welding apparatus for welding together edge portions of metal strip which are in overlapping relation, said strip having a finite, predetermined width and a predetermined thickness and the desired weld being between the overlapping portions and extending along a line substantially equal in length to the width of said strip and said overlapping portions being in conductive contact at least at the ends of said line, said apparatus comprising a conductive anvil for supporting said portions and engageable with the lowermost surface of the overlapped portions, a proximity conductor extending along said line from one end to the other thereof and in close proximity but insulated relation to said portions with said portions between said proximity conductor and said anvil, an insulating member extending between said proximity conductor and said portions, a source of current having a frequency such that the reference depth in the metal of said strip is greater than said thickness but such that the metal along said line will reach welding temperature without overheating the metal engaged at the points of contact between said portions, means conductively connecting one end of said anvil and one end of said proximity conductor together, means connecting the opposite ends of said anvil and said proximity conductor to said source and means for pressing said insulating member against said portions.

Claim 71

Apparatus for welding together two metal portions along a desired weld line, comprising: means for holding said two metal portions stationary and in contacting relationship with each other along the full extent of the desired completed weld line prior to being welded, electrically conductive means in stationary conductive contact with at least one of the metal portions at respective regions adjacent opposite ends of the desired weld line but transversely removed from the desired weld line, a source of high frequency welding current having first and second terminals, means for connecting one terminal of said source to said conductive means adjacent one end of the desired weld line at a location removed from the portions to be welded and for connecting the other terminal of said current source to said conductive means adjacent the opposite end of the desired weld line and at a location removed from the contacting portions to be welded, at least one of said connecting means extending along the desired weld line in stationary, closely spaced, but insulating relationship to the two contacting portions to be welded to provide proximity conductor means for causing welding current to flow in the same direction through the portions to be welded and along the desired weld line and for causing current flow in the proximity conductor means to be opposite in direction to the current flow along the desired weld line, thereby to concentrate said current in the region of the desired weld line, and means for applying a force to at least one of the contacting metal portions to simultaneously apply forge welding pressure completely along the desired completed weld line to forge weld said two portions, said means for holding the metal portions in stationary conductive contact being constructed and arranged to permit the forming of said forge weld.

Claim 72

Apparatus for welding together two metal portions along a desired weld line, comprising: means for holding said two metal portions stationary and in contacting relationship with each other along the full extent of the desired completed weld line prior to being welded, electrically conductive means in stationary conductive contact with at least one of the metal portions at respective regions adjacent opposite ends of the desired weld line but transversely removed from the desired weld line, a source of high frequency welding current having first and second terminals, means for connecting one terminal of said source to said conductive means adjacent one end of the desired weld line at a location removed from the portions to be welded and for connecting the other terminal of said current source to said conductive means adjacent the opposite end of the desired weld line and at a location removed from the contacting portions to be welded, at least one of said connecting means extending along the desired weld line in stationary, closely spaced, but insulating relationship to the two contacting portions to be welded to provide proximity conductor means for causing welding current to flow in the same direction through the portions to be welded and along the desired weld line and for causing current flow in the proximity conductor means to be opposite in direction to the current flow along the desired weld line, thereby to concentrate said current in the region of the desired weld line, and means for applying a force to at least one of the contacting metal portions to simultaneously apply forge welding pressure completely along the desired completed weld line to forge weld said two portions, said means for holding the metal portions in stationary conductive contact being constructed and arranged to permit the forming of said forge weld.

Claim 73

Apparatus for welding together two metal portions along a desired weld line, comprising means for holding said two metal portions stationary prior to being welded and with one portion in butting contact along an edge thereof with the other portion, said butting contact being along the full extent of the desired completed weld line along which the portions are to be welded, electrically conductive means in stationary conductive contact with at least one of the metal portions at respective regions adjacent opposite ends of the desired weld line but transversely removed from the desired weld line, a source of high frequency welding current having first and second terminals, means for connecting one terminal of said source to said conductive means adjacent one end of the desired weld line at a location removed from the portions to be welded and for connecting the other terminal of said current source to said conductive means adjacent the opposite end of the desired weld line and at a location removed from the butting Portions to be welded, at least one of said connecting means extending along the desired weld line in stationary, closely spaced, but insulating relationship to the butting portions to be welded to provide proximity conductor means for causing welding current to flow in the same direction through the butting portions along the desired weld line and for causing current flow in the proximity conductor means to be opposite in direction to the current flow along the desired weld line, thereby to concentrate said current in the region of the butting contact of said portions, and means for applying a force to at least one of the butting portions to simultaneously apply forge welding pressure completely along the desired completed weld line to forge weld the butting portions, said means for holding the two metal portions in stationary butting contact being constructed and arranged to permit the forming of said forge weld.

Claim 74

Apparatus for welding together two metal portions along a desired weld line, comprising means for holding said two metal portions stationary prior to being welded and with one portion in butting contact along an edge thereof with the other portion, said butting contact being along the full extent of the desired completed weld line along which the portions are to be welded, electrically conductive means in stationary conductive contact with at least one of the metal portions at respective regions adjacent opposite ends of the desired weld line but transversely removed from the desired weld line, a source of high frequency welding current having first and second terminals, means for connecting one terminal of said source to said conductive means adjacent one end of the desired weld line at a location removed from the portions to be welded and for connecting the other terminal of said current source to said conductive means adjacent the opposite end of the desired weld line and at a location removed from the butting Portions to be welded, at least one of said connecting means extending along the desired weld line in stationary, closely spaced, but insulating relationship to the butting portions to be welded to provide proximity conductor means for causing welding current to flow in the same direction through the butting portions along the desired weld line and for causing current flow in the proximity conductor means to be opposite in direction to the current flow along the desired weld line, thereby to concentrate said current in the region of the butting contact of said portions, and means for applying a force to at least one of the butting portions to simultaneously apply forge welding pressure completely along the desired completed weld line to forge weld the butting portions, said means for holding the two metal portions in stationary butting contact being constructed and arranged to permit the forming of said forge weld.

Claim 75

The apparatus claimed in claim 66 wherein said two portions to be welded are in edge to edge butting contact along the full extent of the desired completed weld lines,

Claim 76

Apparatus claimed in claim 67 wherein said proximity conductor means is a plurality of individual conductors spaced from each other.

Claim 77

Apparatus claimed in claim 67 wherein said electrically conductive means is on one side of the portions to be welded and the proximity conductor is on the opposite side of the portions.

Claim 78

Apparatus claimed in claim 67 wherein said proximity conductor means is comprised of two conductors, one end of each of the conductors being connected to said source and the opposite end of each conductor being connected to the conductive means adjacent respective ends of the desired completed weld line to be formed between the portions.

Claim 79

Apparatus claimed in claim 67 wherein said proximity conductor means is comprised of a single conductor extending substantially from end to end along the desired completed weld line to be formed between the portions.

Claim 80

Apparatus claimed in claim 67 wherein said electrically conductive means comprises at least one continuous bar that extends substantially completely along and closely adjacent the desired weld line, the bar contacting at least on e of the portions to be welded.

Claim 81

Apparatus claimed in claim 67 wherein said conductive means is comprised of a single bar that extends substantially completely along said desired weld line, said bar contacting both of said portions at least at both ends of the desired weld line, the bar being recessed in the region proximate the desired weld line to assure that the bar will not contact the weld formed between the members.

Claim 82

Apparatus claimed in claim 67 wherein said electrically conductive means is comprised of a pair of continuous bars that extend completely along the desired weld line on opposite transverse sides thereof, each of said bars being in electrical contact with a respective portion to be welded at least at regions at the opposite ends of the desired weld line.

Claim 83

Apparatus claimed in claim 67 and further including conductive tie bar means extending transversely between said bars at respective regions beyond the respective ends of the desired weld line, said means for connecting the terminals of said source to the conductive means being respectively connected to the tie bar means.

Claim 84

Apparatus claimed in claim 67 wherein said means for holding the two metal portions in stationary contacting relationship along the desired completed weld line includes stationary supporting means for supporting each of the portions to be welded at respective regions extending parallel to but transversely displaced from said desired weld line, and clamping means extending along respective transverse sides of the desired weld line and engaging the portions to be welded to force the two portions into stationary clamped relationship with said supporting means.

Claim 85

Apparatus claimed in claim 76 whereIn either open of the clamping or supporting means is a continuous structure that is substantially a nonconductor of electricity and extends immediately adjacent, but spaced from, the desired weld line, said proximity conductor means extending along either one of the substantially nonconducting clamping or supporting means in spaced relation to the desired weld line.

Claim 86

Apparatus claimed in claim 76 wherein the supporting means comprises said electrically conductive means and couples welding current to the portions to be welded at respective regions thereof at opposite ends of the desired weld line.

Claim 87

Apparatus claimed in claim 76 wherein the clamping means comprises said electrically conductive means and couples welding current to the portions to be welded at respective regions thereof at opposite ends of the desired weld line.