Since ancient times, bamboo has been widely used in all walks of life. Due to the different influences of bamboo and wood materials, bamboo wood-based panels have many excellent properties in terms of physical and mechanical properties, such as high strength. It has the advantages of good elasticity and impact resistance, and is a good non-wood wood-based board material. Due to the differences in the structure, shape, material properties and wood of bamboo, some processes and equipment still differ, taking the production of bamboo mat plywood as an example: The production process of bamboo mat plywood is: Bamboo mat preparation → drying → coating → blanking → aging → hot pressing → sawing → inspection → ordinary bamboo plywood. It can be seen that the process after the sawing is the same as that of the general plate, and the production process of each process before the hot pressing is different. First, bamboo mat preparation (wood wood panel without this process) The bamboo weaving of bamboo plywood has two kinds of latitude and longitude seats and curtain hanging. The latitude and longitude mat is a bamboo mat woven from 1 to 1.5 mm thick bamboo. The curtain hangs are made of bamboo inner springs and are suspended as curtains in the form of curtains. Second, bamboo mat drying The drying method can be dried naturally or in a mesh belt dryer. The suitable moisture content of bamboo mat is 8-20%. If it is too low, the plate will be brittle, the fluidity of the resin will also be deteriorated, affecting the quality of the glue. If the temperature is too high, the hot pressing time will increase. It must be exhausted several times. The process is difficult to master. The color of the surface becomes black, which affects the physical and mechanical properties and appearance quality of the product. Third, glue There are two kinds of gluing methods: manual gluing and gluing machine. The rubber used is phenolic and urea-formaldehyde. Practice has proved that the use of phenolic glue is better than urea-formaldehyde, but the cost is higher. Fourth, Chen Hua In order to make the glue 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 placed or assembled for a period of time and then hot pressed. Five, the blank When producing bamboo plywood, the blank can be odd or even layer structure (wood plywood can only be an odd structure), and the warp and weft mixed bamboo plywood needs to be staggered. Sixth, hot pressing The appropriate temperature, pressure, and time for hot pressing vary depending on the type of rubber and the number of layers. The temperature of the urea-formaldehyde glue is 120-125 ° C, the temperature of the phenolic glue is 130-140 ° C, the pressure of both is 2.5-4 MPa, the time is lengthened with the increase of the number of layers, and the time of the phenolic glue is longer. At present, bamboo mat bamboo plywood is one of the fastest growing and largest varieties of bamboo wood-based panels in China. It is mainly used as a building formwork, and a small amount of bamboo fiber board made of veinaldehyde rubber is used as a package board. The traditional wood formwork construction surface quality is poor, the assembly cost is time-consuming, and the construction period is long. The steel molds promoted in the 70s are small in size, large in seams, heavy in weight, difficult to demould, rough in surface, and easy to rust and deform; The wood plywood formwork used in the ages requires a large amount of wood resources, and the number of turnovers is small, and the cost is high, so it is not suitable for large-scale use. Bamboo mat bamboo plywood has high strength and good toughness; wide width and less joints; smooth surface, easy demoulding; water resistance, heat resistance, no deformation; high turnover times, has been widely used in construction, replacing Wood molds, steel molds, and wood plywood are used as concrete templates for high-rise buildings, bridge dyes, dams, and tunnels. There are dozens of production enterprises in the country, mainly in Hunan, Hubei, Jiangxi, Zhejiang, Anhui and other places. The development of bamboo wood-based panels is fast, the product cost is low, and the application is wide. However, due to the late development, it is in its infancy. Like the wood-based panels, there are problems such as poor quality and insufficient performance. In the future, it is necessary to develop bamboo materials suitable for production. The high-precision equipment of plywood and the improvement of the manufacturing process to expand the product market enable the smooth development of bamboo wood-based panels.
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Stainless steel of grade 304 contains nickel of 8% and chromium of 18% and is the most commonly used grade for the production of fasteners. It possesses an excellent combination of strength, corrosion resistance and fabricability. Fasteners of this grade are being extensively used today in almost every industry.
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