The roll is a tool for plastic deformation of metal (rolling material), and it is also an important vulnerable part that determines the efficiency of the rolling mill and the quality of the rolling material. The roll is an important part of the rolling mill in the rolling mill. It uses the pressure generated by a pair or a group of rolls to roll and grind the steel. It mainly bears the influence of dynamic and static load, wear and temperature change in the rolling process.
There are two kinds of rolls we usually use, cold rolling rolls and hot rolling rolls.
There are many kinds of materials for cold rolling, such as 9Cr, 9Cr2, 9Crv, 8CrMoV, etc. This type of roller has two requirements
1. The roller surface should be quenched.
2. The surface hardness shall be HS45 ~ 105.
The material of the hot rolling roll is generally 60CrMnMo, 55Mn2, etc. Rollers of this type can be used in a wide range of fields. Can be used for steel, bar, thread steel, high-speed wire, seamless steel pipe, billet and other processing. It is subjected to strong rolling forces, severe wear and thermal fatigue. In addition, the hot roller works at high temperature, allowing diameter wear per unit workload, so there is no need for surface hardness, only high strength, toughness and heat resistance. Hot rolling only use the whole normalizing or quenching, surface hardness requirements HB190 ~ 270 hardness.
The common failure forms and reasons of roller are as follows:
High speed steel roll ring manufacturers: crack.
The crack of the roll is mainly caused by the excessive local pressure of the roll and the rapid cooling and heating of the roll. On the rolling mill, if the emulsion nozzle is blocked, resulting in poor local cooling conditions of the roll, cracks will occur. Due to the lower temperature in winter, cracks are more likely to occur than in summer.
High speed steel roll ring manufacturers: peeling.
If the crack continues to develop, it will form a block or flake. The peeling light can be re-polished and reused, peeling serious scrap.
High speed steel roll ring manufacturer: scratch pit.
Pit marking is mainly due to the strip steel weld or other impurities into the rolling mill, so that the roll surface is marked with different shapes of pits. Generally, the roller with scratches should be replaced. When the quality of the strip steel weld is not good, it should be lifted and pressed down when the rolling operation passes through the weld to prevent pitting.
high speed steel roll ring manufacturers: sticky roll.
The reason for sticking the roll is that there are some phenomena such as broken parts, folding waves and broken edges in the cold rolling process, and due to the high pressure and instantaneous high temperature, it is easy to form adhesion between the steel strip and the roll, resulting in less area damage of the roll. Through grinding, the surface cracks of the roll can continue to be used, but the service life is significantly reduced, and peeling accidents are prone to occur in future use.
high speed steel roll ring manufacturers: roller.
Pull roll is mainly due to excessive pressure caused by strip thickness or slight folding, strip deviation caused by thickness. When the roll is severely squeezed, it will stick to the roll and the strip will crack. When the roll is slight, there are marks on the strip steel and the roll.
high speed steel roll ring manufacturers: broken roll.
The main reasons for roll fracture are overpressure (that is, excessive rolling pressure) and internal defects of the roll (non-metallic inclusions, bubbles, etc.).) and the stress field caused by uneven temperature of the roller.