Influence of the geometric parameters of convergent extrusion channel of die on the maximum value of compaction stress of dry ice and on the quality of the obtained pellets
[ 1 ] Instytut Konstrukcji Maszyn, Wydział Inżynierii Mechanicznej, Politechnika Poznańska | [ P ] employee
2023
chapter in monograph / paper
english
- dry ice
- extrusion
- geometric parameters
- quality
EN Dry ice is a material that has a temperature of about -78 °C and sublimates in normal ambient conditions. To reduce the sublimation rate, the outside surface area of the material is limited by compaction of the initial powder. The purpose of this study was to determine the influence of the geometrical parameters of the dry ice extrusion die on the value of the maximum stress induced by compaction and on the quality of the obtained pellets. Conical and straight channel dies were used in this research, each having 16 mm outlet diameter of and 80 mm overall length. Two parameters were variable: the convergence angle of the conical part (2°, 3,5°, 5°, 7.5°, 10° and 15° respectively) and the length of the die as a result and the inlet diameter (20 mm and 28 mm respectively). The tests were carried out on a custom-designed dry ice extrusion facility which included a test machine to apply the force. The force required to press and extrude dry ice through the die channel was recorded and the density of the final product was analysed. The obtained results show significant differences in the force required for the process of extrusion. As to the level of stress, it can be seen that it decreases with the decrease in the diameter and the increase in the convergence angle of the conical part.
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