Sádrové formy s využitím regenerátu

Abstract

In searching for the use of used plaster molds in foundry technology, their application as components with the suitable ratio with new plaster has proven in the new plaster molds. The heat treatment is also important, because of the rise of the insoluble anhydrite II. (β-CaSO4). In the experimental part of work, the dependence of the surface strength and the shear strength of the composite gypsum mixture with the various content of water and mixtures with the using regeners was investigated. The prepared mixtures from the gypsum M028 with the water factor w for the mixture A w = 0,625, the mixture B w = 0,4 and the mixture C with w = 0,303. Mixtures with regeners were prepared in the ratio 1 part of plaster regener to 1 part of the new plaster. The various water factor w 0,6; 0,7 and 0,8 was chosen for each mixtures with regeners A, B and C. The results have showed, that gypsum mixtures with regener solidify in a longer time interval, but they have higher strengths. There is the economics and the ekology advantage for the use of regeners. The plaster molds are used for the lost wax pattern method in the foundry technology. In the work, the strengthes of gypsum mixtures with regeners in the ratio 1:1 is checked for the application in the foundry practice.