Investigation of vibropressing process technology
2011
Kovalska, A., Riga Technical Univ. (Latvia) | Auzins, J., Riga Technical Univ. (Latvia)
The vibropressing process technology is useful for compacting or packing any dispersed or granulometric materials can be applied in agriculture. Vibration is widely used in the preparation of concrete and formation of parts from it [1]. The vibropressing technology means a vibrating of a concrete mix in the press form under pressure. The method is high-efficiency, gives the chance to make rigid concrete that provides high durability and frost resistance of products. To achieve a high compaction rate and high strength of the formed product - paving blocks, bricks etc., the vibration must be combined with high pressure. There is extensive literature on the effects of such features as frequency, amplitude and acceleration, and a lot of literature about rheological models of raw concrete. The results depend on material characteristics such as the difference between its initial density after preparation and its maximum packing fraction, the coefficient of friction between the grains, the angularity of particles etc. [2]. In the present work the vibropressing process was experimentally modelled on the dynamic testing machines Instron and Zwick. The form of concrete samples was cylindrical. The vibropressing regime, described by formula f=f0+fAsin(ωt) was realizing by changing three input parameters – f0 pressing force (10-50 kN), fA force amplitude (1-11kN) and frequency (10-50 Hz). The experiments were conducted according to the Mean Square Error Latin hypercube design [3]. The influence of the pressing force, force amplitude and frequency on the vibropressing process [4] and on the strength of samples was investigated.
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