Research On Laisteel Heavy Mill Two-in-one Center Sill Section Steel Rolling Approach

Van center sill, called the back of van, is the main essential component of railage vehicle, which bears the most load and is the most important part of van. Its intensity will directly affect the configuration performance of the railway. As the railway vehicle's speed and weight is increasing, the van center sill can't meet the usage demands any more. Center sill section steel is produced by Z section welding at present due to mill dimension limit. This process makes the welding seam corroded easily and more thickness needed for enough strength, so the production cost is raised. If we use a new process to roll directly center sill section instead of welding, we can not only avoid the welding defect, reduce weight and cost, but also meet the railway's request. So we select the two-in-one rolling technique to produce center sill section steel and its application will bring huge economic and social benefits.Two-in-one center sill section steel is a kind of complex thin wall section steel. There is no steel enterprise rolling mill and process can produce this center sill section steel. Masteel had cooperated with The State Key Lab of Rolling and Automation of Northeastern—RAL. In order to produce this kind of steel earlier and create optimal economic benefits, Masteel and RAL together research on "two-in-one 320 Z section technics design". The height of workpiece and roller diameter difference are too great though Masteel has heavy universal mill. The ratio of up-and-down roller diameter difference in two sides of rolling is up to 1.73. Rollers are easy to break and the economic losing is huge. And the leveling process also has problem. Research of Masteel has to stop because of roller diameter in name and leveling problems.After 2005, Laisteel fetched in heavy universal mill and its roller diameter is bigger than Masteel's. Two-in-one center sill has huge economic benefits, so Laisteel and RAL decide to cooperate about research on "Laisteel heavy mill two-in-one center sill section steel rolling approach". They hope to produce van center sill in Laisteel's heavy mill. In order to reduce risk we use simulate experiment first in RAL because the expense to exploit this kind of steel is too high.Simulate experiments are performed inΦ300 two high inreversing mill of laboratory with lead. The rolling pass scale is 1:5 according to the actual size of the two-in-one center sill section steel. Heat rolling-heat bending technology was adopted in roll pass design in order to make uniform mechanical property.Two experiment methods i.e. sketch blank and billet are used as original blank. According to Laisteel's request we first research on sketch blank provided by Laisteel. Fold can not avoid in reduce process because the width of sketch blank is large which caused large reduction. We should reduce pass reduction in order to avoid fold. Then the number of pass should be increased. Fold problem can not avoid because the number of pass will not increase any more due to the width of Laisteel roller limit.According to the width of Laisteel roller, we used billet to research in the base of sketch blank pass schedule. We use billet can produce the figuration and dimension of two-in-one center sill section steel. We check the Laisteel actual rolling mill based of experimental data. The check results show that the force which roller borne to is a little heavier than roller itself can load. We should check them farther.