The Hot Rolling Mill is used to reheat shapes of steel to soften them enough so that they can be rolled thinner and longer through a series of rolling stands.
The concept is similar to the rolling of dough. Rolling is classified according to the temperature of the metal rolled. If the temperature of the metal is above its recrystallization temperature, then the process is known as hot rolling. If the temperature of the metal is below its recrystallization temperature, the process is known as cold rolling. The finished product can be either a strip, plate, rod, bar, wire, or shape. After the steel is formed to its desired shape, it is cooled so that the desired mechanical properties of the steel product are achieved.
Hot Rolling Mill:
Temperature control is critical throughout the Hot Rolling Mill to assure desired product properties, ensure quality product, improve line speed and process control. There are a number of interferences that can affect the pyrometer reading at every point along the hot rolling mill. These include water, steam, scale, misalignment, and emissivity variation.
Fig. Hot Rolling process
Challenge:
Monitoring and controlling temperature at each stage are important to maintain the quality, properties of the hot rolled product.
The temperature of hot rolling is around 1000°C to 1300°C. The hot rolling mill having a challenging environment for making any kind of temperature measurements like high temperature and the movement of the metal, make thermocouples and other contact temperature sensors impractical.
The main two challenges are as below:
- The environment is very harsh.
- The site’s ambient temperature is very high up to 70°C or 80°C.
AST Solution:
AST Pyrometer with IR focusable & non-focusable, Fast response time and highly accurate pyrometer is the most recommended solution used in hot rolling applications.
Pyrometer:
The AST A250 PL & A 250+ is the most suitable and specially designed pyrometer for such types of applications. Environment being harsh and also high ambient temperature, we suggest water cooling for safety and long life of pyrometer. This AST A250 & A250+ and accessories has the following features:
- Wide temperature ranges start from 210°C
- Emissivity, Response Time adjustable by software
Other Applications:
Application: Billet temperature measurement before entering the rolling
Process Temp: 1000°C
Application: Before Quenching
Process Temp: 900-950°C
Application: After Quenching at the cooling bed.
Process Temp: 450°C-500°C
Benefits:
- Highly accurate and very fast temperature measurement
- Continuous process temperature monitoring
- high performance and low maintenance solution