Review on cold rolling mill roll deformation
Abstract
There are various reasons by which the damage in the cold rolling mill rolls occurs. The main objective is to highlight those reasons which are responsible for the breakage. The parameters considered during the manufacturing and during the regular use of rolls in cold rolling in the past researches and the effect of these parameters to increase the life of a roll. These are based upon the various factors and summarize the effect of parameters responsible for the deformation concluded by the various researchers in the past history of cold rolling mill.
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Introduction
Rolling is one of the oldest process for reducing the cross section of metal sheet, the other metal forming processes like forging, casting, extrusion and others. All these metal forming processes are parameters dependent and tool dependent. For example the forging will be punch and die based, the casting is based upon the mold and the rolling is based upon the rolls. Secondly the hot working and cold working of the metals are effecting the process of forming. In this researc h the various parameters which effects the rolling process are being included and analyzed. The research shows the findings of the past researchers in the field of cold rolling process and the future work about the rolling field. The rolling mill consist of rolls as the main tool, there are various rolling mills depends upon the number of rolls used in the machine. According to the number of rolls the rolling mill can be designed as 20 Hi, 12Hi, 8 Hi, 6 Hi, 4 Hi and 2 Hi rolling mills. In India now a days mostly 20 Hi and 4 Hi rolling mills are installed in big steel production units. Bhushan Steel Gaziabad is having 6 Hi Rolling mill, Jindal Steel Hisar is having 20 Hi and 4 Hi rolling mills, whereas Ruchi Strips and alloys ltd and National steel is having 20 Hi and 4 Hi rolling mills, chiefly the mill is being decided along with the thickness of the strip, the thinner (2 to 3 microns) sheets can be produced by 20 Hi rolling mill whereas the more thick sheets can be produced by 4 Hi or 6 Hi rolling mill (4 to 10 microns).
Conclusion
The main reasons for the deformation in the roll according to the past researchers identified from the manufacturing of the roll to the using the in the rolling mill. The following reasons are responsible for a roll deformation:
1. Thermal breakages:
Three factors are important for thermal breakage:
- Thermal gradient
- Strength
- Residual stress
2. Torsional Breakage of driven roll neck
3. Fire Cracks
4. Local Overload
5. Fatigue
6. Spalling
7. Damage of steel roll due to hydrogen
8. Wear and Friction of rolls
9. Bite angle and coefficient of rolls
10.Design parameters