tailieunhanh - Advanced Welding Processes Episode 2 Part 7

Tham khảo tài liệu 'advanced welding processes episode 2 part 7', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Monitoring and Control of Welding Processes 245 The recent development of low-cost remote computer-based data loggers has made it possible to record welding parameters in the welding environment store the data in battery-backed memory and interrogate the results by downloading the data through a serial link either via a long fibre optic communication cable or by direct connection of the remote data collection unit to a suitable computer figure . This system has been used for measurement of heat-affected-zone temperature cycles thermal testing of welding torches and monitoring of current and voltage 181 . The improved availability of high-speed analogue-to-digital cards for personal computers has also made it possible to develop cost-effective purpose-designed welding data loggers suitable for research production and quality monitoring applications 182 . Figure Portable computer and battery-operated compact data logger. V . MitiitiI i nliiniHtftifffum 5 Ill li-IM-t c Normal welding parameter monitoring Temperature. The high temperatures experienced in welding may be measured using temperature-indicating paints or crayons fusible indicators bi-metal thermometers thermocouples infrared thermometers or by thermal imaging. 246 Advanced Welding Processes Temperature-indicating paints and crayons change colour in response to the surface temperature of the material. They are convenient for site use but their accuracy depends to a certain extent on the care with which they are applied and the interpretation of the colours. Fusible indicators melt and in some cases change shape when they reach a prescribed temperature. They give a clear indication that a certain temperature has been reached but little guidance on the actual temperature of the material during the heating and cooling cycle. Bi-metal thermometers are contact devices which rely on the response of a bi-metal strip to temperature deflection of the strip being converted mechanically into movement of a .

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