SMS Elotherm has two contracts from Sweden’s Ovako Tube and Ring AB to develop and install induction-heating equipment at the plant in Hofors, Sweden. The plant builder indicated it will customize EloBar™ and EloTube™ machines for the projects, combining high energy-efficiency and “a comparatively small space requirement.”
Ovako produces engineering steel for bearings and transportation and engineering applications. The Horfors operation, 220 km northwest of Stockholm, produces 500,000 metric tons/year of ingots, which are processed into billets, bars, tubes, tube components and rings. The tube rolling capacity is approximately 120,000 metric tons/year, and the ring rolling capacity is approximately 45,000 metric tons/year.
The SMS EloBar system will be used to heat steel bars at a rate of up to 8,000 kg per hour. With an installed electrical power of 4,000 kW, bars of up to 130 mm diameter may be heated up to 1,220°C.
SMS Elotherm also is supplying the bar-handling system for the heating process, the induction heater with a hot shear, and an industrial robot to transfer heated bars between the hot shear and ring press.
“EloBar belongs to our ForgeLine series,” noted SMS Elotherm representative Torsten Schäfer which can be designed in a very flexible way. We have configured this energy-efficient system for Ovako precisely to the customer’s needs.”
SMS Elotherm has reported it can customize its EloForge package to heat billets up to 100 mm diameter, or slabs up to 240 mm thick, as well as bar material up to 360 mm OD.
The EloTube installation will be part of a modernization program of Ovako’s tube rolling operation, and installed ahead of an Assel mill (a piercing/rolling line for blooms.) Hollow blooms from an upstream rolling mill will be reheated and equalized by the EloTube installation before the tube line.
“The temperature of the shell is increased to 1,100°C and the better temperature homogeneity leads to enhanced product quality in the Assel mill operation,” explained Dr. Guido Opezzo, a representative of SMS Elotherm: “ Also, the sizing forces can be reduced and the lifetime of the sizing rollers is extended due to less wear and tear.”
The induction system consists of six coils powered by state-of-the-art converters with transistor technology (IGBT), with a total rated power of 6,400 kW. “The demand for floor space of this reheating unit is less than 7 m in length and 2.5 meters in width,” as Elotherm described it.
The process control combines a tube speed measurement system based on Laser Doppler technology and a bicolor pyrometer for temperature measurement. “The induced power is determined by the speed and the incoming temperature of the shell. Overheating of the material is prevented and the optimum temperature level for the following sizing mill operation is achieved,” Opezzo said.
Both the EloBar and EloTube installations at Horfors will be commissioned in mid-2013, SMS Elotherm indicated.
