ANALYSIS AND ASSESSMENT OF FOUNDRY MOULDING SAND PREPARING PROCESS USING THE DYNAMIC POWER MEASUREMENT METHOD

Preparation of moulding sand is a key process, determining the final quality of casting products. Special requirements are imposed at stabilising and optimising the parameters of the moulding sand so that it should maintain its properties required for moulding. These requirements can be satisfied as long as specialised mixing systems are used to prepare and control the sand mixing processes. The key elements of the system include sand mixers supported by dedicated measuring equipment operating in accordance with the approved control methods. Methods employed to determine the key properties of sand mix include the methods applied in on-line mixing control systems. The author's research to date has led to the development of a method whereby the sand quality indicator is defined by a dynamic power demand signal from the mixer system. This study provides the selected measurement data, showing power consumption by the driving units in a prototype turbine mixer, used in laboratory conditions. The experimental programme utilises a state-of-the-art microprocessor system for measuring the parameters having relevance to power consumption by the mixer drive. Measurement signals of power demand by a paddle stirrer and a rotor are analysed. Testing was done for variable moisture content in moulding sands containing different kind of bentonite and for variable mixer pan loads. The methodology is supported by measurements of sand properties by conventional methods. The complete set of data and interrelations holding between them is utilised to describe the investigated processes in terms of dynamic systems, in accordance with the rules of automation. Attention is given to practical applications of the power measurement method in the analysis of mixing dynamics, in control of water-feeding system and in evaluation of energy demand for the process. The proposed methodology enables the comprehensive evaluation and selection of constructional parameters of devices of sand preparation systems.