Rough rolling will make the billet compressed or stretched, and delivers qualified work pieces with the right section shape, qualified size and good surface. Generally the section size of rolled pieces after rough rolling process is more than or equal 50mm.
The rough rolling process is different because there are various raw materials, single line wire mill adopt flat /vertical is alternatively to roll the work piece without twist rolling; other type mills apply twist rolling process by 2-high horizon mill. In practical, except high alloy steel, most steel bars or wires can be produced with twist rolling.
It is necessary to cut off two ends of the rolled pieces after rough rolling. There are different dissipation conditions at the head and tail ends of the rolled parts from the middle part, that brings poor plasticity; uneven deformation causes irregular shapes, which will lead to block up the entrance guide or the rolled parts are failure bite during continuous rolling.
Horizontal two-high rolling mill is more commonly used, especially suitable for carbon structural steel and low-alloy rolling. The rolling line can use close mill, pre-stress mill and short stress line mill. Close mills usually use a trolley to replace the roll set; prestress mill and short stress mill offline to replace the roll or whole housing. It is common to use a separate drive for each stand, that will facilitate the adjustment of the mill and to avoid trouble matching the roll when roll group drive.
Flat/ vertical tandem rolling mill is especially suitable for the production of high-grade alloy steel wire rod. Because the alloy steel has big torsional deformation resistance and poor plasticity, it easily makes cracks and events at twist rolling. Alloy steel wire rod production needs no twist rolling. Flat /vertical alternating tandem mills are often used in multi-species single-line high-speed wire rod mills and adopt individual drive.The vertical rolling mill adopts the downward drive mode except the two-high close stand mill and the short stress mill which adopt the upward drive mode
Short center distance compact rolling mill applies a large deformation to the rolled piece, the bite angle is 38°~42° . Due to the compact mill has large pass deformation, big rolling force, its rolls wear quickly. In addition, the compact mill stand spacing is very narrow. In case of rolling failure, it is hard to solve the trouble in a short time. That will affect the entire mill production time, so the new rolling line rarely uses this type of mill.
