First of all, the definition of plywood Plywood is a plank formed by rotating logs into large veneers along the direction of annual rings, drying and gluing, and then forming blanks and gluing them according to the principle that the wood grain directions of adjacent veneer layers are perpendicular to each other. The number of veneer layers is odd, generally three to thirteen layers, common three plywood, five plywood, nine plywood, and thirteen plywood (commonly known as three plywood, five plywood, nine plywood, thirteen plywood in the market) plate). The outermost front veneer is called the panel, the reverse is called the backplane, and the inner layer is called the core board.
Classification of plywood
One type of plywood is weather-resistant and boiling-water-resistant plywood, which has the advantages of durability, high temperature resistance, and steam treatment;
The second type of plywood is water-resistant plywood, which can be dipped in cold water and hot water for a short time;
The third type of plywood is moisture-resistant plywood, which can be dipped in cold water for a short time and is suitable for indoor use at room temperature. for furniture and general construction purposes;
The four types of plywood are not moisture-resistant plywood, which is used under normal indoor conditions. The general-purpose plywood materials include beech, basswood, ash, birch, elm, and poplar.
Symmetry principle: The veneer on both sides of the symmetrical center plane, regardless of the thickness of the veneer, the number of layers, the manufacturing method, the fiber direction and the moisture content of the veneer, should correspond to each other, that is, the symmetrical principle of the plywood on both sides of the center plane The corresponding layers are in different directions. The stress is equal in magnitude. Therefore, when the moisture content of the plywood changes, its structure is stable, and there will be no defects such as deformation and cracking; on the contrary, if there are some differences between the corresponding layers on both sides of the symmetrical center plane, the stress of the veneer on both sides of the symmetrical center plane will not be affected. Equal, the plywood will be deformed and cracked.
Odd layer principle: Since the structure of plywood is that the fiber directions of adjacent layers of veneers are perpendicular to each other and must comply with the principle of symmetry, its total number of layers must be an odd number. Such as: three-layer board, five-layer board, seven-layer board, etc. When the odd-numbered plywood is bent, the maximum horizontal shear stress acts on the center veneer, which makes it have greater strength. When the even-numbered plywood is bent, the maximum horizontal shear stress acts on the adhesive layer instead of the veneer, which is easy to damage the adhesive layer and reduce the strength of the plywood.
The full name of the veneer is decorative veneer veneer plywood. It is a kind of surface used for interior decoration or furniture manufacturing, which is made by cutting natural wood or technical wood into thin slices of a certain thickness, adhering to the surface of the plywood, and then hot pressing. Material. Common veneers are divided into natural wood veneer veneers and artificial veneer veneers. The appearance difference between artificial veneer veneer and natural wood veneer veneer is that the texture of the former is basically a straight texture or regular pattern; while the latter is a natural wood pattern with natural texture and pattern, with relatively large variability and irregularity. Its characteristics: it not only has the beautiful pattern of wood, but also achieves full use of wood resources and reduces costs.
Plywood is a plywood produced from wood as the main raw material. Due to the rationality of its structure and the fine processing in the production process, it can generally overcome the defects of wood and greatly improve and improve the physical and mechanical properties of wood. The production of plywood is to fully and reasonably utilize wood. , an important method to improve the performance of wood. One of the commonly used materials for furniture is a wood-based panel. A group of veneer is usually formed by gluing the adjacent layers of wood grains perpendicular to each other. Usually, the surface plate and the inner layer are symmetrically arranged on both sides of the center layer or the core. It is a slab made of glued veneers crisscrossed in the direction of the wood grain, and pressed under the condition of heating or no heating. The number of layers is generally odd, and a few are even. The physical and mechanical properties in the vertical and horizontal directions are slightly different. Commonly used are three plywood, five plywood and so on. Plywood can improve the utilization rate of wood and is a main way to save wood. It can also be used for aircraft, ships, trains, automobiles, buildings and packing boxes.
Post time: Sep-04-2022