US3621177A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method and apparatus for tig tube welding
Assignee: Atomic Energy of Canada Ltd AECL
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Filing: 1968-12-09
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Granted: 1971-11-16
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Expires: 1988-12-09
Abstract
Abstract Described herein is a method and apparatus for fully automatically weld-joining lengths of metal instrument tubing employing the TIG welding process to advance a weld puddle about the periphery of the junction of aligned ends of straight tubing, respective end portions of which are held in a closed chamber rigidly clamped in spaced seats of a robust metal head to resist elongation by heating; the unit comprises a handle portion axially separably joined with the head and providing drive to a rotating electrode carrier spool therein about the work, angular interval marking signals being transmitted to a remote control unit from which welding current and gas is supplied to the head according to a weld program selected for the material being joined. A welding cycle commences with a stationary arc developing a weld pool, followed by advance at uniform speed of the arc with controlled current levels over sectors, the arc being sustained beyond 360* and the complete cycle spanning two revolutions of the carrier and terminating with a bead-cooling gas flow. Repeatable welds of high quality on a production basis may be obtained, characterized by minimal fall-in of bead, full area fusion of faces, and constant internal diameter.
Inventors
- 👤 Neil Freeman Mcpherson
- 👤 Nils Hanssmann
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 20:02
CPC Classifications
B; B23; B23K; B23K9/00; B23K9/02; B23K9/028; B23K9/0282; B23K9/16; B23K9/167
Claims Analysis
Total Claims: 36
Claim 1
Independent Claim
158 words
The method of fusion joining metal tubing which comprises aligning end portions of a pair of tubing lengths with their ends abutting and holding said portions as a column in a manner to impose restraint to axial elongation of said column and with the end faces of the abutting ends contiguous, exposing a localized area at the junction of said faces to heating to a fusion temperature by means of a stationary arc in an inert atmosphere to form a weld puddle spanning the junction, said heating being at a rate and for a time effective to induce axial compression by temperature increase of said column, thereafter advancing said localized area of heating at a uniform rate along the entire periphery of the junction while maintaining substantially constant weld puddle fluidity sufficient to effect fusion bonding of said end faces, discontinuing said arc, and maintaining said axial restraint during cooling of the weld to form an inseparable joint.
Claim 2
Independent Claim
158 words
The method of fusion joining metal tubing which comprises aligning end portions of a pair of tubing lengths with their ends abutting and holding said portions as a column in a manner to impose restraint to axial elongation of said column and with the end faces of the abutting ends contiguous, exposing a localized area at the junction of said faces to heating to a fusion temperature by means of a stationary arc in an inert atmosphere to form a weld puddle spanning the junction, said heating being at a rate and for a time effective to induce axial compression by temperature increase of said column, thereafter advancing said localized area of heating at a uniform rate along the entire periphery of the junction while maintaining substantially constant weld puddle fluidity sufficient to effect fusion bonding of said end faces, discontinuing said arc, and maintaining said axial restraint during cooling of the weld to form an inseparable joint.
Claim 3
Dependent Claim
23 words
The method of claim 1 wherein the localized area is advanced through an arcuate distance greater than 360* but less than about 480*.
Claim 4
Dependent Claim
5 words
''a preheating current time interval;
Claim 5
Dependent Claim
5 words
''a preheating current time interval;
Claim 6
Dependent Claim
4 words
a preheat current value;
Claim 7
Dependent Claim
4 words
a preheat current value;
Claim 8
Dependent Claim
18 words
The method of claim 2 wherein the arc is established between a refractory metal electrode and the work.
Claim 9
Dependent Claim
39 words
The method of claim 3 wherein the electrode is moved in a path defining a plane at an adjustable uniform rate of travel and the locus of said path is traced a constant radial distance from the tubing surfaces.
Claim 10
Dependent Claim
19 words
an arcuate interval of 15* while electrode is advancing from end of interval in 2 maintaining value of 3;
Claim 11
Dependent Claim
19 words
an arcuate interval of 15* while electrode is advancing from end of interval in 2 maintaining value of 3;
Claim 12
Dependent Claim
5 words
a main weld current value;
Claim 13
Dependent Claim
5 words
a main weld current value;
Claim 14
Dependent Claim
34 words
The method of claim 4 wherein said end portions are filled with inert gas before welding and a predetermined gas pressure is maintained therein slightly above atmospheric during welding and solidification of the weld.
Claim 15
Dependent Claim
124 words
The method of claim 4 wherein during formation of said weld puddle the arc current is maintained at a constant value while the electrode is held stationary and thereafter while the electrode is rotating the current is reduced and held at a second steady value over a first arcuate interval extending along about 190* of said periphery, then reduced and held at a third steady value over a second arcuate interval extending along about 90* of said periphery, then reduced and held at a fourth steady value over a third arcuate interval extending along about 90* of said periphery, then tapered to a predetermined minimum value over a fourth arcuate interval extending along about 60* of said periphery and finally abruptly reduced to zero.
Claim 16
Dependent Claim
8 words
An arcuate interval about 180* maintaining level 5;
Claim 17
Dependent Claim
8 words
An arcuate interval about 180* maintaining level 5;
Claim 18
Dependent Claim
5 words
a first decreased current value;
Claim 19
Dependent Claim
5 words
a first decreased current value;
Claim 20
Dependent Claim
32 words
The method of claim 6 wherein the electrode is caused to move an arcuate distance of about 15 degrees from the initial weld puddle position before said second current level is maintained.
Claim 21
Dependent Claim
26 words
The method of claim 6 wherein the current level transitions following the terminations of said first, second, third and fourth values of constant current are gradual.
Claim 22
Dependent Claim
9 words
an arcuate interval about 90* maintaining value of 7;
Claim 23
Dependent Claim
9 words
an arcuate interval about 90* maintaining value of 7;
Claim 24
Dependent Claim
5 words
a second decreased current value;
Claim 25
Dependent Claim
5 words
a second decreased current value;
Claim 26
Independent Claim
215 words
The method of fusion joining lengths of metal tubing which comprises aligning end portions of respective lengths and holding said aligned portions coaxial with their ends abutting to form a junction of their end faces, filling said end portions with inert gas and maintaining a predetermined gas pressure therein slightly above atmospheric, initiating a stationary electric arc between the junction and a refractory metal electrode in an inert gas atmosphere and maintaining arc current at a constant initial value and for a time sufficient to form a weld puddle spanning said junction and sufficient to effect a predetermined temperature rise of said end portions while holding said end portions restrained at areas spaced from said junction in contact with a massive electrically conductive and heat-condUctive sink to chill the ends of said column and limit maximum temperature rise therealong, thereafter advancing the arc at a uniform rate about the junction to effect fusion bonding throughout the entire area of said end faces while controlling the arc current to maintain a viscosity of the weld puddle limiting radial distention of the puddle metal to a substantially constant amount offsetting weld shrinkage on cooling, and, while maintaining said axial restrain and predetermined internal gas pressure, cooling the weld bead in inert atmosphere to form an inseparable joint.
Claim 27
Independent Claim
215 words
The method of fusion joining lengths of metal tubing which comprises aligning end portions of respective lengths and holding said aligned portions coaxial with their ends abutting to form a junction of their end faces, filling said end portions with inert gas and maintaining a predetermined gas pressure therein slightly above atmospheric, initiating a stationary electric arc between the junction and a refractory metal electrode in an inert gas atmosphere and maintaining arc current at a constant initial value and for a time sufficient to form a weld puddle spanning said junction and sufficient to effect a predetermined temperature rise of said end portions while holding said end portions restrained at areas spaced from said junction in contact with a massive electrically conductive and heat-condUctive sink to chill the ends of said column and limit maximum temperature rise therealong, thereafter advancing the arc at a uniform rate about the junction to effect fusion bonding throughout the entire area of said end faces while controlling the arc current to maintain a viscosity of the weld puddle limiting radial distention of the puddle metal to a substantially constant amount offsetting weld shrinkage on cooling, and, while maintaining said axial restrain and predetermined internal gas pressure, cooling the weld bead in inert atmosphere to form an inseparable joint.
Claim 28
Dependent Claim
51 words
The method of claim 9 wherein the viscosity of the weld puddle is maintained at a constant value by controlling arc current to predetermined constant values over specific arcuate intervals of the periphery and wherein the arc is advanced through a peripheral distance greater than 360* but less than about 480*.
Claim 29
Dependent Claim
8 words
an arcuate interval about 90* maintaining level 9;
Claim 30
Dependent Claim
8 words
an arcuate interval about 90* maintaining level 9;
Claim 31
Dependent Claim
124 words
a final arcuate interval about 50* steadily decreasing current from level 9 to about 3 amperes at ending; holding specimen lengths of said tubing coaxially in welding position with ends abutting defining a junction of the abutting end faces and correlating specimen position with the starting point; initiating an arc and effecting a first trial automatic welding sequence commencing at the initial value 3 for the interval in 2 and carrying out the remaining trial program; cooling the resulting welded joint; testing the weld, and revising the heat input by varying program integers to correct welding flaws, and repeating the trials with similar specimens using improved program values and subsequent testing to arrive at an optimum program for repetitive automatic welding of said tubing.
Claim 32
Dependent Claim
124 words
a final arcuate interval about 50* steadily decreasing current from level 9 to about 3 amperes at ending; holding specimen lengths of said tubing coaxially in welding position with ends abutting defining a junction of the abutting end faces and correlating specimen position with the starting point; initiating an arc and effecting a first trial automatic welding sequence commencing at the initial value 3 for the interval in 2 and carrying out the remaining trial program; cooling the resulting welded joint; testing the weld, and revising the heat input by varying program integers to correct welding flaws, and repeating the trials with similar specimens using improved program values and subsequent testing to arrive at an optimum program for repetitive automatic welding of said tubing.
Claim 33
Dependent Claim
90 words
The method of claim 10 wherein said arc current is progressively reduced through five levels correlated with respective arcuate intervals of arc advance, commencing with said initial value over a first interval of about 15*, a second value over a second interval spanning about 190*, a third value over a third interval spanning about 90*, a fourth value over a fourth interval spanning about 90*, and a final value continuously decreasing from said fourth value over a fifth interval spanning about 60* to a predetermined minimum value, becoming zero thereafter.
Claim 34
Independent Claim
60 words
The method of realizing a program of decreasing welding current levels for an automatic programmed TIG welding system for fusion bonding aligned lengths of metal tubing of a specific size, wall thickness, and kind of material by means of an electric arc passed between a revoluble refractory electrode and the work, comprising selecting a trial schedule of program integers including:
Claim 35
Independent Claim
60 words
The method of realizing a program of decreasing welding current levels for an automatic programmed TIG welding system for fusion bonding aligned lengths of metal tubing of a specific size, wall thickness, and kind of material by means of an electric arc passed between a revoluble refractory electrode and the work, comprising selecting a trial schedule of program integers including:
Claim 36
Dependent Claim
22 words
The method of claim 12 including the step of recording angular displacement intervals and current values as graphic traces on moving charts.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1974-11-15 | 1975-05-17 | 1975-11-16 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-11-15 | 1979-05-17 | 1979-11-16 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-11-15 | 1983-05-17 | 1983-11-16 | $7700.00 | Window Closed / Lapsed |