Torch height sensing apparatus
AssigneeCaterpillar Tractor Co.
InventorRichard W. Richardson
Life of this patent
Estimating the term…
Abstract
A torch height sensing apparatus (10) is provided for generating information representative of the spacing between a cutting torch (12) and an associated workpiece (14). The apparatus (10) drives a preselected current from the torch (12) through the torch flame to the workpiece (14) so that electrons flow from the workpiece (14) through the flame to the torch (12). The output current biases the flame into the linear region of the preselected voltage-current characteristic at a positive torch (12) to workpiece (14) current. Biasing the torch (12) for positive current flow from the torch (12) to the workpiece (14) insures that flame height sensing occurs in the positive linear region where the sensitivity is greatest due to the availability of thermally emitted electrons at the workpiece.
Claims18
A torch control system (10) for controlling the proximity of a torch (12) to a working piece (14) comprising:
- a torch (12);
- means (16,18) for effecting relative, toward and away, movement between the torch (12) and a workpiece (14);
- means (22,24) for interconnecting a workpiece (14) and said torch (12) for causing electrons to flow from a workpiece (14) to the torch (12) at a predetermined varying rate;
- means (26) associated with said interconnecting means (22,24) for detecting a predetermined characteristic of the electron flow;
- and
- means (26,28) responsive to said detecting means for operating the moving means and controlling the distance between the torch (12) and a workpiece (14).
An apparatus (10) for generating a signal representative of the resistance of a cutting torch flame, comprising:
- means (22,24) for producing current increments in step-wise fashion, including a zero current step, and driving the current from the torch (12) through the flame thereof to the workpiece (14) so that electron flow is from the workpiece (14), along the flame and to the torch (12);
- and
- means (26) for detecting the voltage at each step of current flow including said zero current step.
An apparatus (10) for generating a signal representative of the spacing of a cutting torch (12) from a workpiece (14) said torch (12) having a flame with a preselected voltage-current characteristic having a linear portion at a positive torch-to-workpiece current, comprising:
- means (22,24) for producing a current signal having a plurality of incremental steps and driving the current signal through the torch flame, the current level at each step lying substantially along the linear portion of the preselected voltage-current characteristic;
- and
- means (26) for detecting the voltage across the torch flame.
A method for generating a signal representative of the spacing of a cutting torch (12) from a workpiece (14), comprising:
- biasing the torch (12) positive with respect to the workpiece (14);
- generating a preselected voltage-current characteristic having a linear portion at a positive current;
- producing a current signal;
- driving the current through the torch flame;
- maintaining the current substantially along the linear portion of the preselected voltage-current characteristic;
- and
- detecting the voltage across the torch flame.
A method for generating a signal representative of the spacing of a cutting torch (12) from a workpiece (14), comprising:
- biasing the torch (12) and inducing a positive current flow from the torch (12) to the workpiece (14);
- producing a current signal;
- driving the current incrementally from the torch (12) through the torch flame to the workpiece (14);
- and
- detecting the voltage across the torch flame for a plurality of current increments.
Dependencies are inferred from the claim text.