Views:4518 Author:Site Editor Publish Time: 2020-05-27 Origin:Site
Since ancient times, bamboo has been widely used in all walks of life. Due to the different effects of bamboo and wood itself, bamboo wood-based panels have many excellent properties, such as high strength and elasticity, that are not comparable to wooden wood-based panels in terms of physical and mechanical properties. And good impact resistance and other advantages, it is a very good raw material for non-wood based panels. Due to the difference between the structure, shape, wood properties and wood of bamboo, some processes and equipment are still different. Take the production of bamboo mat plywood as an example:
The production process of bamboo mat plywood is as follows: bamboo mat preparation → drying → gluing → blanking → aging → heating → saw edge → inspection → ordinary bamboo woven plywood.
It can be seen that the process after sawing is the same as the general plate treatment method, and the production process of each process before hot pressing is different.
1. Preparation of bamboo mats (there is no such process for wood-based panels); there are two kinds of bamboo weaves for warp and weft mats and curtain hanging mats. The warp and weft mats are bamboo mats woven from 1 to 1.5 mm thick bamboo pieces. The curtain hanging mat is a bamboo mat which is hung in the form of curtains by using the inner spring of bamboo material.
2. Bamboo mat drying; the drying method can be natural drying or mesh belt dryer. The suitable moisture content of the bamboo mat is 8-20%, too low will easily cause brittleness of the board, and the resin fluidity will also deteriorate, which will affect the quality of the glue. Too high will cause the hot pressing time to increase. The color of the surface becomes black, which affects the physical and mechanical properties and appearance quality of the product.
3. Glue; There are two methods of gluing: manual gluing and gluing. The types of glue used are phenolic glue and urea-formaldehyde glue. Practice has proved that the use of phenolic glue is better than urea-formaldehyde glue, but the cost is higher.
Fourth, aging; so that the glue can fully infiltrate the bamboo mat and improve the quality of the glue. After the glue is applied, the bamboo mat should be placed for a period of time and then assembled into a blank or after a period of time and then hot pressed.
V. Group billets; when producing bamboo woven plywood, the group billets can be odd-numbered or even-layered (wood plywood can only be odd-numbered), and the warp and weft mixed bamboo woven plywood need to be staggered to form the billet.
Sixth, hot pressing; the appropriate temperature, pressure and time during pressing vary according to the type of glue and the number of layers. The temperature of urea-formaldehyde glue is 120-125 ℃, the temperature of phenolic glue is 130-140 ℃, the pressure of both is 2.5-4 MPa, the time increases with the increase of the number of layers, and the time of phenolic glue is longer.
At present, bamboo mat bamboo curtain plywood is one of the fastest-growing and largest-scale varieties of bamboo wood-based panels in China. It is mainly used as a building template, and a small amount of bamboo aldehyde plywood is used as a packaging box board. The surface quality of traditional wooden formwork construction is poor, the assembly is laborious and time-consuming, and the construction period is long; the steel molds introduced since the 1970s have a small breadth, many joints, heavy weight, difficult demolding, rough surfaces, and are easy to rust and deform; 80 The wood plywood formwork used since the beginning of the year is not suitable for large-scale use because of the large amount of wood resources required and the low turnover times and high cost. The bamboo mat plywood has high strength and good toughness; the breadth is wide and the joints are few; the surface is smooth and easy to demold; water resistance, heat resistance, no deformation; high turnover times and other characteristics, it has been widely used in construction to replace Wooden formwork, steel formwork, and wood plywood are used as concrete forms for high-rise buildings, bridge dyeing, dams, and tunnels. Now there are dozens of production enterprises nationwide, mainly distributed in Hunan, Hubei, Jiangxi, Zhejiang, Anhui and other places.
The development of bamboo-based wood-based panels is rapid, the product cost is low, and the use is wide. However, due to the late development, it is in the initial stage. Like wood-based wood-based panels, there are problems such as poor quality and insufficient stability. In the future, it is necessary to develop suitable bamboo materials for production. The high-precision equipment of plywood and the improvement of the manufacturing process to expand the product market can enable the smooth development of bamboo wood-based panels.