电阻式旧砂在线检测水分仪设计

Design of Resistance Moisture Detector for Used Sand

为了在线检测铸造中旧砂含水量,研制出一种新型的电阻式水分仪。设计出以STM32F103C8T6微控制器为核心的激励电压电路、采样电路、有源滤波放大电路、模数转换电路、电流转换电路和电极故障检测电路等电路,并编写了控制程序。为了提高水分仪的可靠性,在外部测量电路与内部控制电路之间采用数字隔离芯片进行隔离,同时也启用了微控制器内置的看门狗定时器。所研制的水分仪具有性能和参数长期稳定、无需现场调试的优点。

In order to on-line measure the moisture of old sand in casting,a new resistance moisture meter is developed.The excitation voltage circuit,sampling circuit,active filter circuit,analog-to-digital conversion circuit,current conversion circuit and electrode fault detection circuit based on STM32F103C8T6 microcontroller are designed,and the control software is programmed.For the sake of improving the reliability of moisture meter,a digital isolation chip was used to isolate the external measuring circuit and the internal control circuit,and the internal watchdog timer was also applied in the microcontroller.The developed moisture meter has the advantages of long-term stability of performance and parameters and no need to debug on site.