Portable Cold Spray Gun Nozzle Plugging and Flow Control
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Solution Overview
Problem
Prior gas dynamic spray guns face issues such as nozzle plugging due to large particles, high-pressure requirements for powder delivery, uneven coating layers from pulsation in powder feed systems, and inadequate heating units for portable applications.
Innovation Solution
A portable gas dynamic spray gun with a powder flow rate sensor and controller to adjust gas and powder flow rates, a vibrating powder feed system for consistent delivery, and a compact heating unit to maintain efficient operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If powder is injected into the heated main gas stream prior to passage through the nozzle, then the powder can be conveyed at high velocity, but the powder tends to plug the nozzle throat causing backpressure and malfunction
Solution Approach 1:
The system separates powder injection from the main heated gas stream by using a dedicated powder delivery system with separate heating, avoiding the plugging issue while maintaining high velocity conveyance
Solution Approach 2:
A carrier gas acts as an intermediary to convey powder particles without direct contact with the hot main gas stream, preventing plugging while enabling high velocity delivery
2Productivity
If high-pressure powder delivery systems are used to deliver powder at high velocity, then the powder can be conveyed effectively, but the systems are expensive and difficult to use in portable applications
Solution Approach 1:
The system changes the pressure parameter by using atmospheric or low-pressure carrier gas instead of high-pressure systems, reducing complexity while maintaining effective powder delivery through optimized nozzle design
Solution Approach 2:
The system uses pneumatic principles with carrier gas flow to convey powder at controlled velocities without requiring complex high-pressure delivery mechanisms
3Temperature
If a heating unit is made large to heat the carrier gas sufficiently, then the heating is adequate, but the spray gun is no longer portable
Solution Approach 1:
The system applies heating locally only where and when needed in the powder delivery path, using compact heating elements that provide sufficient temperature rise without requiring large heating units
Solution Approach 2:
The system uses partial heating of the carrier gas to the extent necessary for effective powder delivery, rather than excessive heating, reducing the size and weight of the heating unit while maintaining portability
4Device complexity
If the powder feed rate is not continuously monitored and adjusted, then the system is simpler, but the deposition efficiency and coating uniformity are poor due to parameter scatter
Solution Approach 1:
The system incorporates sensors and controllers that continuously monitor powder feed rate and adjust delivery parameters in real-time, providing feedback control to maintain consistent deposition efficiency and uniform coating quality
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 minimizes parameter scatter, improves deposition efficiency, prevents nozzle clogging, and ensures uniform coating layers while being suitable for portable use.
Implementation Method 1
A light emitter transmitting light across a duct through which the powder travels. A light receiver mounted opposite the light emitter determines the flow rate of the powder based upon the amount of light received from the light emitter.
Implementation Method 2
A nozzle in the passageway forms the pressurized air into a supersonic jet stream.
Implementation Method 3
A powder feed passage leads to the passageway and supplies powder at a controlled rate to the passageway, where it is entrained in the gas and exits the spray gun in the supersonic jet stream.
Data Source
AI summary
A portable gas dynamic cold spray gun eliminates many of the inherent limitations of the prior art by minimizing a scatter of operating parameters and improving its efficiency. According to one feature of the present invention, the powder flow rate is continuously measured so that the powder flow rate and/or the flow rate of the pressurized gas can be adjusted accordingly in order to control the deposition efficiency of the spray gun.