Research On Roll Force Telemetering System Based On Adhesion Type Sensor

Roll force is one of some important parameters in the processing of steel rolling. So far, Roll force is measured directly at home and aboard. It is difficult to install and maintain roll force monitoring system on rolling mills. It is difficult to lay the signal transmission wire, and the wire can be burned down by the oxide skin fallen off from the hot rolling billet. In order to solve the problem, roll force monitoring system based on wireless transmission which aims to "install and play" is developed.It is difficult to install and maintain conventional supporting type sensor, the supporting type sensor inhabits the space of the rolling mill housing window and affects the performance of rolling mill. In order to solve the problem, the system adopts the adhesion type sensor. The adhesion type sensor is installed on the outside of the rolling mill housing. It obtains roll force by measuring the strain of the housing. So it does not affect the performance of rolling mill and it is convenient to install and play. But the output signal includes large drift signal when the adhesion type sensor is applied to the hot rolling mill. By analyzing the operation of the adhesion type sensor and the wave of actual output signal, it is found that the radiation of the hot rolling billet leads to the temperature difference between the housing and the sensor, and it is the main reason that the sensor outputs drift signal. But when it is rolling, the billet is inside the housing, the temperature difference between the inside and outside of the housing increased, the bend distortion and the expanding distortion counteract each other in the place where the sensor is installed. Thus the output signal of the sensor has the characteristic of "time allotment". It is that the output signal does not include drift signal when the rolling has began, the output signal is drift signal when there isn't rolling.The intelligent signal conditioning circuit is composed of X9241,AD623,ADC and MCU. It is designed to overcome the disadvantage that the adhesion type sensor outputs drift signal. MCU analyzes the collected signal, distinguishes the drift signal, compensates the drift signal by controlling digitally controlled potentiometer, thus it can implement the real-time auto-calibration of the zero-scale of the sensor. It is difficult to lay and maintain the signal transmission wire, so the wireless transceiver model based on nRF401 is used to implement the wireless transmission. Considering the system calls for real-time signal of both sides, the wireless transmission system adopts two channels and point to point design. The sensors on both sides of the rolling mill employ one channel respectively, they can communicate with the wireless transceiver model separately at bit rates up to 19.2kbit/s. The wireless transceiver models on both the transmitter and receiver adopt half-duplex communication in order to implement the initialization and the auto-recognization of the sensor.It is the integrated sensor by integrating the adhesion type sensor, intelligent signal conditioning circuit and wireless transceiver model. If the integrated sensor is installed according to the communication protocol and specification of installation, when the power supply is switched on, the system can auto-recognize it, thus the roll force monitoring system can implement "install and play".