Development Of The Device For Fast Measuring Molding Sand Permerbility

Permeability is an important performance index of molding sand.It is ofgreat significance to improve casting quality and the production efficiency thatmolding sand permeability can be measured quickly and conveniently in thecasting production field.The development method of a new type of device for fast measuringmoulding sand permeability was introduced in this thesis, which included thedevice frame, design method of hardware and software. And the contrast testresults between the new device and standard device were given and analyzed.The new device was mainly composed of the fast sample preparation device,small gas storage room, micro pump, micro pressure sensor and data acquisitionand processing unit. Because of the special structure of main-and-assistant tube,and the constant pressure generated by spring, the speed and precisiong of thefast sample preparation could be ensured in this device. Based on the thought thatconstant pressure was placed by variable pressure, permeability was got bymeasuring the pressure of gas storage room and micro pump. And the volume andweight of the device are reduced greatly. Data acquisition and processing unitwas mainly composed of STC89C52microcontroller,1602LCD and PCF8591TA/D converter, which had fullfiled the real-time acquisition of time and pressure,parameter calculation and results display. The main program and subprogram ofdata acquisition and processing unit were programmed by C51language. Themain program of STC89C52microcontroller mainly performed testing dataprocessing and controlled various peripheral chips and circuit.The subprogramwas mainly composed of keyboard scanning subprogram, A/D conversionsubprogram, LCD display subprogram, and measured value subprogram.The contrast experimental results under the laboratory condition showedthat the new device not only had higher testing speed and more portable structure than the standard one, but also easy operation and accurate measurement results.And thus the device is suitable for fast testing the molding sand permeability inthe foundry field.