This article mainly introduces the forming process of rigid polyurethane foam composite plate. Rigid polyurethane foam composite plate takes foam as the core material and thin steel plate, aluminum plate, plastic school and asphalt paper as the surface material. This type of board is lightweight, strong, has good insulation effect, and has a high surface quality. It is an ideal insulation material for buildings and cold storage. This type of board is also known as sandwich panel. Composite panels can be produced through intermittent or continuous processing
The forming principle of this method is shown in Figure 7-16, which is the composite forming method of the interval song style. The metering pump in the foaming machine injects chemical raw materials into the mixing head, mixes them evenly, and then injects the raw materials into the mold cavity through the injection hole of the mold. The surface material has been pre placed in the mold cavity. After foaming and curing, the sheet can be removed from the mold.
The advantage of this processing method is that the equipment is simple and suitable for multi variety production. According to the application needs, choose flat or convex surface materials as the surface layer of the composite board. The size of the board produced by this method can reach 8m long, 1.5m wide, and 35-150mm thick. The general ruler is 3m long, 1.2m wide, and 75mm thick. The density of foam plastic is 35-60kg/m. In Figure 7-16, there is a partition between the molds, so several plates can be obtained at one time. The foaming machine uses a flow of 50kg/min to inject raw materials into the mold. For the plate with a size of 3mx1.2mx0.075m, when the density of foam plastic is 40kg/m3, inject all raw materials in 13s, and then mature for 10-45min to obtain the product. It is easy to produce 30m2 of sheet metal per hour using this molding method. The disadvantage of this method is that the labor cost is relatively high.
When producing boards using this method, attention should be paid to adjusting the foaming time parameters of the formula. For boards of different lengths, different formulas should be selected. For example, for a 1m long small molded foam, the formula with faster curing speed can still meet the requirements of the molding process, but for a longer plate, the rapid curing raw material system is obviously not applicable, because when producing plates, foam raw materials must be fully filled into the mold cavity before gel can be made, otherwise it is difficult to make products with uniform foam density. At this time, formula with longer interval between milky white time and gel time should be selected. To achieve this goal, a delayed catalytic system can be chosen. The variety of polyether polyols also has a certain impact. It is advisable to have a low content of impurity potassium ions in polyether. The AA vertical composite board forming method is mainly used for manufacturing large and thick boards. The refrigerated warehouse requires composite panels with a thickness greater than 0.1m, and this method of processing is very suitable. Figure 7-17 is a schematic diagram of the vertical composite board forming process. The raw materials from the foaming machine are moved back and forth along the length direction of the plate through the soft material pipe, and the foam plastic with a fixed height is added every time it moves back and forth until the top. The length of the board produced by this method depends on the conveying conditions of the board, and the typical dimensions are 12m long, 1.2m wide, and 150mm thick.
