Plasma arc torches and methods of operating and testing the same
First Claim
1. In a plasma torch comprising relatively displaceable electrode and nozzle means having first and second positions relative to one another in which said electrode respectively contacts said nozzle means and is spaced an operating distance from said nozzle means, said nozzle means providing a gas chamber having a plasma outlet opening, means for flowing gas into said chamber, means for flowing an arc current between said electrode and nozzle means, and means for relatively displacing said electrode and nozzle means between said first and second positions, whereby a starting arc is created as said electrode and nozzle means move from said first toward said second position, the improvement comprising:
- said means for relatively displacing said electrode and nozzle means including means selectively operable for relatively displacing said electrode and nozzle means from said second position toward said first position during the flow of gas into said chamber and independent of the flow of arc current between said electrode and nozzle means.
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Accused Products
Abstract
A plasma arc torch comprises relatively displaceable electrode and nozzle components having first and second positions relative to one another in which the electrode respectively contacts the nozzle and is spaced an operating distance therefrom. Arrangements are disclosed for relatively displacing the electrode and nozzle between the first and second positions thereof with a pre-determined force of engagement therebetween in the first position, and without having to interrupt the flow of arc gas and/or the flow of arc current during such relative displacement. A torch start up safety test procedure is performed by sequentially displacing the electrode and nozzle between the two positions thereof, sensing for appropriate open and closed circuit conditions therebetween, and enabling the creation of a pilot arc only when a pre-determined sequence of circuit conditions is sensed. Sequential displacement of the electrode and nozzle together with the application of a pre-determined force of engagement therebetween promotes cleaning of oxides from the area of contact between the electrode and nozzle.
102 Citations
84 Claims
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1. In a plasma torch comprising relatively displaceable electrode and nozzle means having first and second positions relative to one another in which said electrode respectively contacts said nozzle means and is spaced an operating distance from said nozzle means, said nozzle means providing a gas chamber having a plasma outlet opening, means for flowing gas into said chamber, means for flowing an arc current between said electrode and nozzle means, and means for relatively displacing said electrode and nozzle means between said first and second positions, whereby a starting arc is created as said electrode and nozzle means move from said first toward said second position, the improvement comprising:
- said means for relatively displacing said electrode and nozzle means including means selectively operable for relatively displacing said electrode and nozzle means from said second position toward said first position during the flow of gas into said chamber and independent of the flow of arc current between said electrode and nozzle means.
- View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29)
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30. In a plasma torch comprising relatively displaceable electrode and nozzle means having first and second positions relative to one another in which said electrode respectively contacts said nozzle means and is spaced an operating distance from said nozzle means, said nozzle means providing a gas chamber having a plasma outlet opening, means for flowing gas into said chamber, and means for creating a starting arc by relatively displacing said electrode and nozzle means from said first toward said second position, the improvement comprising:
- a system for controlling said means for creating a starting arc including means for creating a voltage across said electrode and said nozzle means, detecting means for detecting a closed circuit condition when said electrode and nozzle means are in said first position, and enabling means for enabling said means for creating a starting arc only if said detecting means detects a closed circuit condition when said electrode and nozzle means are in said first position.
- View Dependent Claims (31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42)
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43. A method of testing a plasma torch prior to starting thereof, said torch comprising relatively displaceable electrode and nozzle members having first and second positions relative to one another in which said electrode respectively contacts said nozzle and is spaced an operating distance from said nozzle, said method comprising:
- applying a test voltage between said electrode and nozzle, sensing for a closed circuit condition when said electrode and nozzle are in said first position, and enabling creating a starting arc between said electrode and nozzle only when a closed circuit condition is sensed with said electrode and nozzle in said first position.
- View Dependent Claims (44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61)
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62. In a plasma torch comprising relatively displaceable electrode and nozzle means having first and second positions relative to one another in which said electrode respectively contacts said nozzle means and is spaced an operating distance from said nozzle means, said nozzle means providing a gas chamber having a plasma outlet opening, means for flowing arc gas into said chamber, means for flowing an arc current between said electrode and nozzle means, and means for relatively displacing said electrode and nozzle means between said first and second positions, whereby a starting arc is created as said electrode and nozzle means move from said first toward said second position, the improvement comprising:
- means for creating a first force for holding said electrode and nozzle means in said second position, and means for selectively creating a second force for overriding said first force and relatively displacing said electrode and nozzle means from said second position to said first position against said first force.
- View Dependent Claims (63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84)
Specification