Composite molding process
DATE：2021/9/24 8:26:17 / READ： / SOURCE：This station
Composite molding process
This article mainly introduces the forming process of rigid polyurethane foam composite board. The rigid polyurethane foam composite board uses foam as the core material, and uses thin steel plate, aluminum plate, plastic school and tar paper as the surface material. This kind of board has light weight, high strength, good heat insulation effect and high surface quality. It is an extremely ideal heat insulation material for buildings and cold storage. This kind of board is also called sandwich board. The composite board can be made by indirect or continuous processing
(1) Jaga-type compound molding method Figure 7-16 shows the molding principle of this method. The metering pump in the foaming machine pumps the chemical raw materials into the mixing head. After the mixing is uniform, the raw materials are injected into the mold cavity through the injection hole of the mold. The face material has been placed in the cavity of the mold in advance. After foaming and curing, the plate can be taken out of the mold.
The advantage of this processing method is that the equipment is simple and it is suitable for multi-variety production. According to the needs of the application, a flat or four-convex surface material is selected as the surface layer of the surface composite board. The size of the plate manufactured by this method can be up to 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 is 35-60kg/m. There are partitions between the molds in Figure 7-16, so several boards can be obtained by one foaming. The foaming machine uses a flow rate of 50kg/min to inject the raw materials into the mold. For a board with a size of 3mx1.2mx0.075m, the density of the foam is 40kg. /m3, inject all the raw materials in 13s and mature for 10-45min to get the product. With this forming method, it is very easy to produce 30m2 of plates per hour. The disadvantage of this method is higher labor costs.
When using this method to produce boards, pay attention to adjusting the foaming time parameters of the formula. For boards of different lengths, different formulations should be used. For example, for a small molded foam material with a length of 1m, the formula with a faster curing speed can still meet the requirements of the molding process, but for a longer board, the fast-curing raw material system is obviously not suitable, because when the board is produced After the foam material is injected into the mold, it must be completely filled in the cavity before it can be gelled, otherwise it is difficult to make a product with uniform foam density. At this time, a formula with a longer interval between milky white time and gel time should be selected. To achieve this goal, an extended catalytic system can be used. The variety of polyether polyols also has a certain impact. The impurity potassium ion content in the polyether is preferably low. The AA vertical composite sheet forming method is mainly used to manufacture large and thicker sheets. The cold storage requires a composite board with a thickness greater than 0.1m, and this method is very suitable for processing. Figure 7-17 is a schematic diagram of vertical composite sheet forming. The raw materials discharged from the foaming machine are moved back and forth along the length of the plate through the soft material tube. Each back and forth movement is performed to increase the foam with a fixed height to the top. The length of the plate produced by this method depends on the conveying conditions of the plate, and the typical size is 12m long, 1.2m wide, and 150mm thick.
Author：admin