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3856 |
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Friday, May 23, 2014, Hall A 11:40 AM Process Diagnostics, Sensors & Controls |
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New approach in monitoring and control of the thermal spraying |
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Yuri Chivel* / MerPhotonics, France |
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For complete control of the process of thermal spraying it is necessary to measure the parameters of the particles flow - temperature of the particles, size and velocity, including cold particles, and the parameter of surface temperature during coating . A new apparatus for monitoring and control of thermal spraying process contain : a digital video camera based on CCD arrays with a lens and the turning mirror , a light receiving unit with the lens and 2 photodiodes with filters, illumination device. All of the above components are mounted in the housing ΒΈ placed on the movable spray gun head . The signals from the photodiodes and the video camera is processed by the processing unit and digitally transmitted via a WiFi radio transmitter ,also placed on the movable gun head, to the receiver unit , located away from the transmitter. The signals from the receiver unit are transmitted to a computer, which produces signal processing. As a result of processing color temperature of the surface during the coating process and particle flow-rate, temperature, and particle size distribution can be determined. Illumination of the particles flow when cold particles are registered is conducted using a compact cw lasers, visible or infrared, power of ~ 2 W or more, the emission of which is focused into a strip of ~ 2-3 x 15 mm, located along axis of the particle flow. Lasers are powered from independent sources. The continuously recorded parameters makes it possible to control the process of spraying adjusting the speed of the spray head, the pressure of the carrier gas and its heating, the mass flow rate of the powder. Absence of cables and fibers makes it possible to control the processes in the industrial conditions The results of optical monitoring of cold spray and pulsed plasma spraying are presented and discussed. |