Plasma Torch Liquid Injection for High-Speed Marking
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Solution Overview
Problem
Existing plasma arc torch systems are limited in their ability to mark and cut metal workpieces at high speeds without compromising marking quality, as they require changes in consumables and have restricted nozzle diameters, leading to low marking speeds and poor line quality.
Innovation Solution
A plasma arc torch system that uses larger-diameter nozzles and a liquid-injection shield cup to inject liquid tangentially into the plasma arc, allowing for high-quality marking and cutting without changing consumables, with the ability to operate at varying arc currents and liquid flow rates for increased marking speed and precision.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a small-diameter nozzle is used to achieve high arc density and high-quality marks, then marking quality is improved, but marking speed is limited to low speeds
Solution Approach 1:
The patent changes the physical state of the shield medium from gas to liquid (water). This parameter change allows the use of larger nozzle diameters (0.070 inch and larger) while still achieving high arc density and high-quality marks, thereby enabling marking speeds up to 600 ipm without compromising marking quality
Solution Approach 2:
The patent introduces a liquid injection system that delivers water to the shield cup, replacing the traditional gas shielding system. This hydraulic approach allows for better arc confinement and higher marking speeds while maintaining mark quality, as the liquid provides more effective shielding and cooling compared to gas
2Productivity
If water mist is added to the shield gas to increase marking speed, then marking speed is modestly increased, but marking quality deteriorates and speed is still limited to about 300 ipm
Solution Approach 1:
The patent extracts water mist from the shield gas mixture and uses pure liquid water in a dedicated liquid injection system. This separation allows for optimized liquid flow rates and better control over the shielding process, achieving marking speeds up to 600 ipm while maintaining high marking quality without the limitations of gas-based systems
Solution Approach 2:
The patent changes the shield medium from a gas or gas-mist mixture to pure liquid water. This parameter change enables significantly higher marking speeds (up to 600 ipm) while maintaining mark quality, as the liquid provides superior arc confinement and shielding compared to gas-based systems
3Productivity
If the nozzle diameter is increased to enable high-speed marking, then marking speed can be increased, but arc density decreases and marking quality deteriorates
Solution Approach 1:
The patent replaces the gas shielding system with a liquid (water) injection system. The liquid provides superior arc confinement and shielding compared to gas, allowing the use of larger nozzle diameters (0.070 inch and larger) while maintaining high arc density and producing high-quality marks at speeds up to 600 ipm
Solution Approach 2:
The patent changes the physical state of the shielding medium from gas to liquid water. This parameter change enables the use of larger nozzle diameters while maintaining high arc density and marking quality, as the liquid provides more effective arc confinement and shielding than gas-based systems
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables high-speed marking up to 600 inches per minute on stainless steel with improved line quality, including smaller line width, darker color, and reduced surface roughness, while maintaining the capability for cutting at different arc current levels without altering torch components.
Implementation Method 1
a liquid-injection shield cup to inject liquid tangentially into the plasma arc
Implementation Method 2
plasma arc torch system that uses larger-diameter nozzles and a liquid-injection shield cup to inject liquid tangentially into the plasma arc
Data Source
AI summary
A plasma arc torch both cutting and marking of metal workpieces includes a plasma nozzle having a plasma nozzle orifice through which an electric arc from an electrode and a stream of plasma gas are emitted toward a workpiece, and a liquid-injection shield cup that injects liquid tangentially inwardly to the arc and stream of plasma gas. A power supply is operable to selectively deliver electrical power to the electrode at either a low power level suitable for marking of a workpiece or a high power level suitable for workpiece cutting. The torch may be selectively operated to mark at the low power level, with a plasma marking gas being delivered to the plasma gas passage, or to cut at the high power level, with a plasma cutting gas being delivered to the plasma gas passage, and liquid being delivered to the liquid injection passage for both cutting and marking.