Concentric Plasma Torch Nozzles for Shock-Free Jet Intensification
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Solution Overview
Problem
Current plasma cutting technologies face challenges in maintaining high power density and avoiding shock structures in the plasma jet when increasing nozzle pressure, leading to reduced performance and precision in cutting.
Innovation Solution
A plasma cutting torch design featuring a first nozzle with a concentric second nozzle to control the surrounding pressure around the plasma jet, maintaining a pressure ratio between the nozzle exit and the surrounding environment between 1 and 5, which contains and intensifies the plasma jet, while regulating the gas supply pressures to enhance current density and power density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the gas supply pressure in the nozzle is increased to obtain a fine and supersonic plasma jet, then the plasma jet velocity and concentration are improved, but shock structures are generated in the plasma jet at the exit of the nozzle which reduce power density
Solution Approach 1:
A second nozzle is introduced as an intermediary component between the first nozzle and the workpiece. This second nozzle creates a controlled intermediate pressure zone that acts as a mediator to prevent shock structures from forming in the plasma jet, while still allowing the high-velocity plasma to reach the workpiece effectively.
Solution Approach 2:
The solution moves from a single-nozzle one-dimensional system to a two-nozzle three-dimensional system. By adding the second nozzle concentrically around the first nozzle, the system creates a multi-dimensional flow structure that controls pressure distribution in radial and axial directions, preventing shock wave formation while maintaining plasma velocity.
2Object-affected harmful factors
If the distance between the electrode and the cutting plate is increased to reduce shock wave interactions, then the harmful shock effects are reduced, but the power density available at the sheet substantially decreases due to thermal diffusion
Solution Approach 1:
The second nozzle serves as an intermediary that creates a controlled pressure environment, allowing the plasma jet to maintain its integrity and power density over the cutting distance without being disrupted by shock waves interacting with the molten metal.
3Manufacturing precision
If a small diameter nozzle is used to obtain a fine plasma jet, then the kerf width is reduced and cutting precision is improved, but the power density is reduced due to thermal diffusion over longer distances
Solution Approach 1:
By transitioning from a single-nozzle system to a concentric two-nozzle system, the invention adds dimensional complexity that enables simultaneous achievement of fine plasma jet (through the small first nozzle) and maintained power density (through the pressure control of the second nozzle).
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
The solution enables a finer, more energetic plasma jet with increased power density and improved cutting precision, allowing for faster and thicker cuts with reduced kerf width, enhancing the overall efficiency and productivity of the plasma cutting process.
Implementation Method 1
A current is caused to circulate between an electrode and the sheet to be cut so as to form electric arc plasma. A nozzle concentrates this plasma which is heated by the Joule effect to reach very high temperatures.
Implementation Method 2
Because of the high temperature, the sheet melts locally and the gas supply pressure generates the plasma jet out of the nozzle, whose velocity makes it possible to eject the molten metal under the sheet.
Implementation Method 3
the gas supply pressure generates the plasma jet out of the nozzle, whose velocity makes it possible to eject the molten metal under the sheet
Data Source
AI summary
A plasma cutting method providing a plasma torch having an electrode disposed within a first nozzle with a first exit section facing an end of the electrode. The first gas source supplies a gas to the first nozzle. A second nozzle is arranged concentrically around the first nozzle and has a second exit section substantially facing the first exit section. A second gas source supplies the gas between the first nozzle and the second nozzle. The electrode is supplied with a current, and the first and second nozzles are supplied with the gas to form a plasma with the gas introduced into the first nozzle. The surrounding pressure around the plasma jet in the second nozzle at the exit of the first nozzle is controlled to be at least superior to the atmospheric pressure and inferior to the pressure in the first exit section.