- Nov 03, 2015 -
The foamed particles are cooked into the mold cavity, heated in the cavity to 110 ~ 120 ℃, so that the surface of the foam particles together; at the same time because of the foam particles in the evaporation and foaming foam The expansion of the air inside the particles, resulting in internal pressure, so that the foam particles closely attached to the cavity wall surface, after cooling, reduce the internal pressure, and then to the top of the ejector, after forming products with light and tough, Sealed, nest cells do not absorb water characteristics. The density level of the product is inversely proportional to the expansion ratio, and the expansion ratio should be determined in advance according to the density determined by the product performance requirements and product specifications. The molding time of the product (cycletime) refers to the time from the feeding to the stripping time. The length of the molding time in addition to the characteristics of the selected raw materials related to the most important is the steam, cooling water and compressed air, the supply conditions must be stable in order to achieve a certain standard in order to make products off good, good adhesion, smooth surface, And to achieve the goal of shortening the molding time. According to different specifications of the product, these process parameters will be different, should be based on specific requirements.
The following is a group of expansion polymer polystyrene board molding process parameters for reference.
① main steam pressure: 5 ~ 7kg / cm2;
② cooling water pressure: 3.5 ~ 5kg / cm2;
③ cooling water temperature: 23 ~ 28 ℃;
④ compressed air: 5 ~ 7kg / cm2;
⑤ vacuum: a 600 ~ 650mmHg.
The molded sheet, which has been stripped out, is in a vacuum state as in the case of the preformed foamed particles, particularly at a high magnification, and is liable to shrink in the thin-walled portion due to the shrinkage pressure generated by the cooling and decompression. The moisture on the surface of the forming sheet and the condensed steam in the foamed particles must be restored and evaporated by atmospheric pressure.
The molding sheet with the expansion ratio of 60 times or less is placed enough for 1 day in the warehouse. However, the molding sheet with high expansion ratio must be cooked in the drying room at 50 to 60C in order to obtain a satisfactory product. After the maturing of the plate, its hardness, strength than the mold release will be significantly increased.