US3569661A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method and apparatus for establishing a cathode stabilized (collimated) plasma arc
Assignee: Air Products and Chemicals Inc
•
Filing: 1969-06-09
•
Granted: 1971-03-09
•
Expires: 1989-06-09
Abstract
Abstract Disclosed is a method and apparatus for establishing a cathode stabilized (collimated) plasma arc. The invention is characterized in that by utilizing a hollow tubular cathode and causing the cathode arc spot to locate on the inside wall of the cathode electrode the plasma arc becomes collimated and stabilized.
Inventors
- 👤 Robert W Ebeling Jr
- 👤 George A Klasson
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 17:40
CPC Classifications
H; H05; H05H; H05H1/00; H05H1/24; H05H1/26; H05H1/32; H05H1/34; H05H1/341; H05H1/3421; H05H1/3436
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
101 words
A method for establishing a collimated plasma arc between an elongated tubular open-ended cathode directed at a workpiece and the workpiece comprising: surrounding at least a portion of the hollow cathode with a flow of plasma arc gas directed toward the workpiece; establishing an arc between the cathode end directed at the workpiece and an intermediate electrode; and causing a quantity of arc gas to flow into the hollow cathode in a direction away from the workpiece to locate the cathode arc spot on the interior wall of the cathode so that a collimated arc plasma issues from the hollow cathode.
Claim 2
Independent Claim
101 words
A method for establishing a collimated plasma arc between an elongated tubular open-ended cathode directed at a workpiece and the workpiece comprising: surrounding at least a portion of the hollow cathode with a flow of plasma arc gas directed toward the workpiece; establishing an arc between the cathode end directed at the workpiece and an intermediate electrode; and causing a quantity of arc gas to flow into the hollow cathode in a direction away from the workpiece to locate the cathode arc spot on the interior wall of the cathode so that a collimated arc plasma issues from the hollow cathode.
Claim 3
Dependent Claim
32 words
A method according to claim 1 wherein the arc to the intermediate electrode is transferred to the workpiece after the cathode arc spot is positioned on the interior wall of the cathode.
Claim 4
Dependent Claim
19 words
A method according to claim 1 wherein there is provided a shielding gas for surrounding the collimated plasma arc.
Claim 5
Dependent Claim
48 words
A method according to claim 1 wherein the arc gas is caused to flow into the hollow cathode by a chamber surrounding the hollow cathode and having an orifice between the cathode and the workpiece with an orifice diameter greater than the inside diameter of the hollow cathode.
Claim 6
Independent Claim
128 words
A method for establishing a collimated high pressure arc between an open-ended hollow cathode, the cathode selected from the group consisting of tungsten and thoriated tungsten, and a workpiece comprising: surrounding at least a portion of the hollow cathode with a flow of arc gas consisting of those gases inert to tungsten directed toward the workpiece; establishing an arc between the cathode end directed at the workpiece and an intermediate electrode; causing a quantity of arc gas to flow into the hollow cathode in a direction away from the workpiece so that the cathode arc spot moves into the interior wall of the cathode; and transferring the arc from the intermediate electrode to the workpiece so that the collimated plasma arc is between the cathode and the workpiece.
Claim 7
Independent Claim
128 words
A method for establishing a collimated high pressure arc between an open-ended hollow cathode, the cathode selected from the group consisting of tungsten and thoriated tungsten, and a workpiece comprising: surrounding at least a portion of the hollow cathode with a flow of arc gas consisting of those gases inert to tungsten directed toward the workpiece; establishing an arc between the cathode end directed at the workpiece and an intermediate electrode; causing a quantity of arc gas to flow into the hollow cathode in a direction away from the workpiece so that the cathode arc spot moves into the interior wall of the cathode; and transferring the arc from the intermediate electrode to the workpiece so that the collimated plasma arc is between the cathode and the workpiece.
Claim 8
Dependent Claim
18 words
A method according to claim 5 wherein there is provided a shielding gas for the collimated plasma arc.
Claim 9
Dependent Claim
48 words
A method according to claim 5 wherein the arc gas is directed into the interior of the cathode by a chamber surrounding the hollow cathode and having an orifice between the cathode and the workpiece with an orifice diameter greater than the inside diameter of the hollow cathode.
Claim 10
Dependent Claim
90 words
A plasma welding torch comprising: an elongated tubular cathode having a generally cylindrical-shaped bore throughout; means defining a chamber around said cathode for surrounding at least a portion of one end of the cathode with an arc gas; an orifice in said chamber positioned between the end of the cathode surrounded by the arc gas and a workpiece; the orifice being of a sufficiently small diameter to cause a portion of the plasma-arc gas to flow up into the hollow cathode; and means to provide electrical energy to the cathode.
Claim 11
Dependent Claim
90 words
A plasma welding torch comprising: an elongated tubular cathode having a generally cylindrical-shaped bore throughout; means defining a chamber around said cathode for surrounding at least a portion of one end of the cathode with an arc gas; an orifice in said chamber positioned between the end of the cathode surrounded by the arc gas and a workpiece; the orifice being of a sufficiently small diameter to cause a portion of the plasma-arc gas to flow up into the hollow cathode; and means to provide electrical energy to the cathode.
Claim 12
Dependent Claim
23 words
A plasma welding torch according to claim 8 wherein the orifice has a diameter larger than the inside diameter of the hollow cathode.
Claim 13
Dependent Claim
26 words
A plasma torch according to claim 8 wherein the hollow cathode of a material selected from the group consisting of tungsten, thoriated tungsten and mixtures thereof.
Claim 14
Dependent Claim
23 words
A plasma torch according to claim 10 wherein the extreme end of the cathode surrounded by the arc gas has a rounded configuration.
References Cited (Backward Citations)
US3118046A
Cited
US3377457A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1974-03-08 | 1974-09-07 | 1975-03-09 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-03-08 | 1978-09-07 | 1979-03-09 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-03-08 | 1982-09-07 | 1983-03-09 | $7700.00 | Window Closed / Lapsed |