The temperature on the barrel of the disposable foam plate making machine increases from the charging section to the junction between the cylinder and the forming die. The molding die temperature is slightly higher than the barrel temperature. The higher temperature shall be controlled at 5-10 ° C. The temperature at both ends of the mold is slightly higher than that in the mold, and the higher temperature is controlled at 5-10 ° C. The upper roll surface of the intermediate roll of the three rolls shall be in a horizontal plane with the lower plane of the die lip; The lip end face is parallel to the center line of the intermediate roll, with a distance of 50 ~ 100mm.
The die lip gap shall be slightly less than or equal to the thickness of the plate product, and the middle gap of the die lip shall be slightly less than the gap of the end die lips on both sides. Note that the roughness r of three roll working surface shall not be greater than 0.2pm. When cleaning the roll surface, do not scratch the roll surface with a hard steel knife, but use a copper knife to clean the residual materials on the roll surface. The roll surface shall have some medium height; The gap between the three rollers shall be equal to or slightly greater than the thickness of the plate.
The temperature control of forming die shall be stable. When the temperature is high, the flow speed of molten material in the die becomes faster; When the temperature is low, the flow speed of molten material in the die becomes slower. Unstable melt flow rate will cause large longitudinal thickness error of plate (sheet) products. Pay attention to control the working surface temperature of three rollers. The temperature of feed roller should be slightly higher and that of discharge roller should be slightly lower. The roll surface temperature is high, the slab is not easy to take off the roll, and the product surface is easy to produce transverse lines; The temperature is low and the surface of the product is not shiny. According to this phenomenon, the roll surface temperature control should be adjusted in time.
The running speed of the three rollers is slightly higher than the extrusion speed of the slab from the die mouth, and the general speed difference is no more than 10%. The working speed of the three rollers should be controlled stably. Too fast or too slow running speed has a great impact on the thickness error of the plate. For the extrusion molding of plastic plates (sheets), except that PVC, polyethylene and polypropylene resins generally do not undergo dehumidification treatment before extrusion, other plastics (such as ABS, polyamide, etc.) shall require dehumidification and drying treatment before extrusion. Otherwise, it shall be extruded by exhaust extruder.
Post time: Dec-01-2021