An Approach to Measure the Temperature Distribution of Hot-Rolled Wire Loops in the Stelmor-Controlled Cooling Line

Stelmor system is usually used to control cooling uniformity and rate of hot-rolled wire loops to obtain the desired mechanical properties. First of all, it is necessary to accurately measure the temperature distribution of wire loops. However, there are some shortcomings in the current methods due to the grid structure of overlapping wire loops. This article proposes a new measurement method. The target region is captured dynamically based on the temperature distribution characteristics of the thermal image. The effective radiation between the wire loops is analyzed by building an effective emissivity model. The probability distribution test confirms the validity of the model. The temperature measurement experiment shows that the temperature data measured by our approach are more stable and accurate than those of current pyrometers. Anticipated results indicate the potential application in improving process technology. For example, the transverse temperature distribution curve obtained based on this approach can be used to guide the configuration of air volume during the cooling process of the wire loops to improve product quality.

I. Introduction

Stelmor is a very popular controlled cooling process [1], [2]. It can adjust the cooling rate before the phase transformation to obtain the desired mechanical properties of wire loops [3]. However, the cooling rate is usually not uniform in different regions due to the complex geometrical structure of wire loops [4], as shown in Fig. 1(a). Therefore, it is very crucial to measure the temperature distribution of wire loops for improving the microstructure and mechanical properties (see SI of supplementary materials for details). Fig. 1.

Wire loops on the roller conveyor during the cooling process. (a) Practical overlapping state. (b) Theoretical overlapping state. The size of wire is mm, diameter of wire loop is 1150 mm, conveying speed is 0.625 m/s, and rolling speed is 25 m/s.