During the curing process of EPS automatic air cooling block molding machine, the beads are cooled by air, and the foaming agent and water vapor in the cell pores condense into liquid, thus forming a vacuum in the cell. At the same time, the air penetrates into the cell through the cell membrane, so that the pressure inside the cell is balanced with the external pressure. This will make the pre expanded beads elastic. In the process of aging storage, foaming agent also diffuses outward, so the shelf life of pre expanded beads can not be too long.
The plastic sheet forming machine consists of two stages, steam heating and cooling settings. The aged pre cured beads are heated by steam. For about 10 to 50 seconds, the air doesn't flow out and creates pressure after expansion. At this point, the softening of the polymer, the pressure generated by the evaporation of the foaming agent and the pressure generated by the air in the battery are greater than that of the external vapor pressure. The bead expands again and expands into a bead gap to form the whole, forming the EPS foam molding product with the same shape as the mold, which is cooled by water or air. It can be molded and done.