2022.12.02
The foam molding process of expandable polystyrene foam can be divided into two steps: the first step is to fill the mold cavity with the pre-expanded polystyrene particles machined from the cooked foam board; the second step is to add When the particles reach the softening temperature, the foaming agent in the cells evaporates into gas and the heating medium infiltrates to further expand the particles. Due to the limitation of the cavity volume of the mold, the expanded particles fill the entire cavity space and are fused as a whole. After being shaped by the cold-proof Lilong machine, the mold is opened and taken out, which is the expandable polystyrene foam molded and foamed product.
Steam molding foaming is a commonly used and economical method for the manufacture of expandable polystyrene foam products and block materials. The method is to fill the mold cavity with mature pre-expanded particles, close the mold and press the mold to prevent the foaming process from opening. The steam for heating enters the cavity directly through the small holes or slots on the inner wall of the mold, the particles are heated and softened, the foaming agent in the cells of the particles evaporates into gas and steam penetrates into the cells, and the particles expand further to increase the volume, due to the limitation of the cavity space , the expanded particles fill the cavity space and fuse into a whole. After cooling and shaping, the mold is opened and taken out, which is a good-quality polystyrene foam product.
The steam molded and foamed product needs to be dried in a drying room (50-60 degrees) after being taken out of the mold to remove the moisture on the surface of the product.
The foaming process in which the particles expand and fuse together takes place in a closed cavity, and the gaps between the particles gradually decrease until they disappear during the foaming process, so the flow resistance of the steam entering the cavity increases gradually, and the steam pressure Raise to a predetermined pressure value, which is called the molded foam pressure, that is, the end point of the molded foam molding. At this time, the steam is turned off, the heating is stopped, and the cooling is set.
Compression foam molding pressure is directly related to the density of foam plastic products. In addition, the density of foamed plastic products depends on the density of pre-expanded particles, that is, the density of pre-expanded particles is different, and the molding pressure of foaming is also different.
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