Working principle of coiler

The coiler with tension reel is used in reversible or irreversible cold rolled steel plate or strip rolling line. This kind of coiler is not only used for coiling (unfolding) the rolled piece, but also for producing tension on the rolled piece. This is to keep the rolling process stable, make the plate coil tighter, and make the rolled piece have the correct direction when feeding into the roll and rolling out from the roll. In the rolling process, it is generally necessary to maintain the front tension and back tension. Depending on these tensions, the pressure acting on the roll during rolling can be reduced, and the warpage of strip steel can be reduced, which is conducive to improving the surface quality of strip steel.

On the single stand reversing cold rolling mill, there are coilers with tension reels in front and back of the mill, which alternately become active or passive, that is, one coiling and the other unfolding. In the continuous or irreversible single stand cold rolling mill, the coiler is installed only at the rear of the mill and the uncoiler is installed at the front of the mill.

When rolling the first pass, after the strip is fed from the decoiler to the work roll of the rolling mill, the pressing plate or roll guide plate is used to compress the strip to produce a small back tension for rolling; then, the strip enters into the jaw of the coiler drum to clamp the strip head for coiling to produce a front tension. The disadvantage of reversible cold rolling is that both ends of strip cannot be rolled. In order to reduce the waste consumption at both ends, large diameter steel coil is often used or the leading strip is welded at both ends of the strip.

In the process of coiling strip, the coil diameter is changing, which causes the continuous change of coiling speed. In order to make the coiling speed adapt to the rolling speed and keep the tension constant during strip rolling, the speed of coiler is required to be adjustable, and the speed range should adapt to the change of rolling speed and coil diameter. Therefore, adjustable DC motor drive is generally adopted.

At the end of rolling, the coil has to be unloaded from the drum, so the coiler drum must be cantilever. However, the reel is coiling the strip steel under great tension, so the reel shaft has to bear great load (including the weight of the reel, the weight of the strip steel coil, the moment caused by bending and tension, etc.). In order to ensure the rigidity and strength of the drum shaft and reduce the bending of the drum shaft, in addition to increasing the size of the drum shaft, a rotatable bracket is generally installed at the free end of the drum. When coiling the strip steel, the support supports the free end of the reel; when unloading the coil, the support turns to the side, which does not hinder the unloading. During coil unloading, the coil is pushed out from the drum by the coil pusher or the coil pusher with coil unloading trolley, and then transported away. Figure 9-2 is the schematic diagram of the pusher. It is composed of hydraulic cylinder 1 and pusher plate 3. Generally, the pusher is set under the reel, and its travel is controlled by limit switch. The push plate itself is a small car, which can run back and forth along the track parallel to the drum to realize the roll pushing work.