Method for manufacturing curved laminated veneer lumber

Abstract

The invention belongs to the field of wood processing and discloses a method for manufacturing curved laminated veneer lumber. By the method, a plurality of layers of veneers are parallelly assembled, glued and hot pressed along the grains according to the following conditions: a, each veneer has the same breadth size and the moisture content of lower than a fiber saturation point; b, loose sides and tension sides or front sides and back sides of all veneers are kept in the same direction during parallely assembling; and c, one or more parameters of the veneers, such as the moisture content, thickness and density are increased or reduced layer by layer. In the method, the conventional plane hot press can be directly used without a die, so the production cost is saved, and the production cycle is shortened. As the bending of a product is determined by the nature of the laminated veneer lumber and is not influenced by the action of external force, the problem of serious resilience is solved, and sustained bending of the laminated veneer lumber can be realized.

Description

technical field [0001] The invention belongs to the field of wood processing, and relates to a method for manufacturing a curved veneer laminated structural material. Background technique [0002] In many application fields, it is necessary to make wood or wood products into special shapes (that is, non-planar shapes) to meet the requirements of use functions. For example: chair backs, cable trays, circular column beams, etc., need to use external effects to bend the materials into the required radians to meet the design bending requirements. [0003] The degree of curvature of the product can be measured by "curvature W" (divided into "instantaneous curvature W 1 ” and “Permanent bending degree W 2 ”) to describe quantitatively. Take laminated veneer structural members as an example (see figure 1 ). figure 1 a is a planar product made by flat pressing method, figure 1 b is the state of the product just after the bending process (ie: instantaneous bending), and figure ...

AI Technical Summary

Problems solved by technology

Especially when steel moulds are used, the cost is too high, and the price of the product will increase when it is passed on to consumers; if wood moulds are used, the frequency of mold loss is too high, and a large number of molds need to be spared

The design of the mold itself also brings design costs

[0006] (2) The rebound of the product is serious

Wood is elastic and plastic. If the hot-pressing temperature is low and the hot-pressing time is short, and the wood is still in the elastic stage, the shape rebound will occur immediately after the finished product is withdrawn from the press; in order to reduce the rebound rate , requires high hot-pressing temperature and long hot-pressing cycle, which brings defects such as high energy consumption and wood carbonization

What's more serious is that because wood is a typical "expansion and shrinkage" material, when the humidity in the environment is high, it will actively absorb moisture and expand; when the humidity in the environment is low, it will passively release moisture and shrink when the environment is low. And "wet expansion and shrinkage" will generate stress inside the product, resulting in deformation of the product

Therefore, even if high temperature, high pressure, and long-term molding processes are used, when wood products absorb moisture in the use environment, expansion and shape recovery will still occur, resulting in partial or complete loss of use functions of the products.

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