How to make sandwich panels?

A plate made of a surface material with a lighter density and lower strength as the core material and a higher bonding strength. Also known as sandwich plate. The surface materials of this board are plywood, fiberboard, plastic plate and metal plate, and the core materials are balsa wood, rubber, acetate fiber, plastic, paper or cloth impregnated with resin (or not impregnated) and metal honeycomb structure materials. Its main advantages are: ① the specific strength of the board is high. (2) The core material is cheap, the dosage is large, the flour material is expensive and the dosage is small, and the production cost of the product is low. (3) Reasonable selection and collocation of face core materials can effectively meet the performance requirements of pre-designed plates. For example, metal cladding is selected to improve the fire resistance and water resistance of the board, and decorative board or plastic board is selected as the surface layer to improve its decorative effect. The board was successfully studied in the United States in the late 1960s, when it was mainly used in aircraft manufacturing, and then gradually extended to architectural decoration such as partitions, doors and floors, as well as furniture parts and refrigerator shells. Subsequently, some countries also produced it one after another, so its application scope is expanding day by day, and it is an important light and high-strength material. Paper honeycomb sandwich panel, referred to as paper honeycomb panel, is widely used in China. Its production process is shown in figure 1.

Figure 1 Preparation of Core Materials

The core material is a honeycomb structure material with a certain size. Usually, kraft paper is rolled up one side by one with special gluing equipment, and the gluing parts on adjacent layers of paper are staggered by half of the distance between two glue strips, and the width of the gluing line is the length of one side of a regular hexagon (as shown in Figure 2). The paper is laminated and glued into a pile, then cut into a certain width (that is, the thickness of the honeycomb core) by a grass cutter, and then heated to solidify the glue, and the two ends are pulled apart to form a hexagonal honeycomb structure. Other structural shapes can also be obtained by adjusting the gluing position and width of kraft paper of adjacent layers (Figure 3). In order to improve the strength, water resistance and corrosion resistance of paper honeycomb structure, paper can be treated with phenolic resin, and its dosage is 15% of paper. If it exceeds this amount, the economic benefit will be poor.

Figure 2

Fig. 3 Adhesion between surface material and core material

Select surface materials according to product requirements. Fiberboard is often used in wallboard, roof panel and door leaf of mobile homes; Cabinet furniture is mostly plywood or veneer. When the surface material is glued to the core material, the core material is usually placed in a wooden frame with the same thickness as the core material, and the upper and lower surfaces of the core material are covered with glued panels. The kind of glue used depends on the surface material. If the surface is wooden, you can use urea-formaldehyde glue or phenolic glue. Then hot pressing, the pressure used should not be too high, otherwise the core material will be compressed and deformed or displayed on the veneer, generally 0.2 ~ 0.3 MPa. After trimming, planing, edge punching (air permeability) and surface treatment, the honeycomb board is glued.