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Abstract: In the anticorrosive coating line of a welded tube plant, the current status and existing problems of the medium-frequency induction heating equipment were discussed. Partial renovations of the power control cabinet have been conducted. Parameters such as the DC current, DC voltage, intermediate frequency power, heating temperature and the positioning signal at the pipe end were collected. A data acquisition and processing system, which can process data according to user needs and provide convenient data processing functions, has been developed using LabVIEW software. This system has been successfully applied in the coating line for the automatic control of high-power induction heating equipment, production management, and digital steel tube and/or digital delivery.
Key words: induction heating; data acquisition; data processing; coating line; welded steel tube
1 Introduction
Induction heating based on the principle of electromagnetic induction, generates eddy currents in metallic materials when exposed to an alternating magnetic field, thereby heating the metals to high temperatures. This method is widely used in the melting,rolling, welding, and heat treatment of various metals and their alloys. Induction heating with a frequency ranging from 50 Hz to less than 10 kHz is commonly referred to as medium-frequency induction heating. By the end of the 20" century, domestic technology for medium-frequency induction heating equipment had become well-developed and began to see widespread industrial applications '?. In the steel pipe manufacturing industry, high-power medium-frequency induction heating equipment is widely used for seamless steel pipe heat treatment, high-frequency welded pipe heat treatment, and the production of anticorrosion coatings on the outer surface of large-diameter pipeline pipes. However, in the early stages, the automation control level of the medium-frequency heating equipment was relatively low, the manufacturing technology in small and medium-sized enterprises was outdated, and many users had limited or basic requirements for the control functions of the equipment. Problems such as incomplete protection, lack of process data recording, and absence of temperature closed-loop control still exist in medium-frequency induction heating equipment to some extent.
At Baosteel, the welded pipe anti-corrosive coating production line was put into operation in 2009, featuring 3 200 kW-1 000 Hz medium-frequency induction heating equipment designed and manufactured domestically. The DC current, DC voltage , medium-frequency voltage, output power, and other parameters of the induction heating...