Research On Image-based Fluidity Evaluation Method And Device Of Liquid Metal

The fluidity of liquid metal is one of the characteristic parameters of alloy casting.At the moment,the existing liquid metal fluidity evaluation methods are mainly based on the spiral test method.Evaluation results of this method are limited,the measurement parameters are limited to the final filling length,and the pouring process and final determination require manual participation,which,thus,takes a long time and has low measurement accuracy.Therefore,it is of great significance to find an accurate and efficient liquid metal fluidity evaluation method and device through research for the casting performance of alloy.This paper proposes a liquid metal fluidity evaluation method and device based on image processing on the basis of spiral test method.The main research contents are as follows:To begin with,this paper concludes and analyzes the existing techniques of liquid level measurement in sprue cups,and proposes a method of liquid level height measurement based on extracting the edge characteristics of liquid level in sprue cups.According to the principle of similar flow process of water and liquid metal casting,combined with the design principle of pouring system,a water simulation experiment is developed to determine the liquid level measurement model of the pouring cup.The model is then used to complete the accurate calibration under the specific camera environment and the error analysis of the measurement model.The research results show that the error of the liquid level height caused by the actual measurement and the focal length of the camera is less than 0.3mm.The feasibility of the liquid level measurement model of the sprue cup is thus verified.Then,based on the liquid level measurement model of the sprue cup,the liquid metal fluidity evaluation device is designed and selected.According to the hardware structure,the device includes an automatic pouring plate,a temperature detection plate and a data acquisition and processing plate.Among them,the industrial camera is set above the sprue cup composed of graphite crucible and heating ring and the position is fixed.The video collected is transmitted to the PC end through wired mode.The sprue cup is placed on the resin sand mold of two boxes containing spiral cavity inside.Automatic pouring is realized by electric push rod lifting.The temperature of metal liquid in the pouring cup is obtained by thermocouple and displayed in real time by temperature instrument.After that,the liquid metal fluidity software is developed and tested.With Python as the development environment,the software uses Opencv database for quick extraction of the liquid level edge of the pouring cup,and Pyqt5 for GUI interface design.The functions realized by the software include: actual height of liquid level,height of liquid level descent,actual output capacity,filling length,pouring video display and filling speed curve drawing.Finally,the software and device are used to establish the actual test system to complete the aluminum alloy fluidity test.Through multiple sets of fluidity experiments at different pouring temperatures,the relationship between the liquid level change measured by the software and the flow length function of the actual spiral sample is fitted.After the test system is corrected,the test is verified.Compared with the actual spiral sample length,the average error of the flow length measured by the test system is 0.93 %,which meets the liquid metal fluidity measurement standard.