Veneer lumber (LVL) is a veneer made by rotary cutting, which is sequentially assembled in the direction of the grain, and the ends are slanted, lapped or butted, and then pressed by gluing and hot pressing. A high-strength structural material with a flexural strength of 18 MPa, a shear strength of 1.7 MPa, and an elastic modulus of 10000 MPa. The VL has the characteristics of uniform engineering performance and flexible specifications. It is superior to solid wood and is particularly suitable for use. VL on large-span wood structures is particularly favored by plywood manufacturers and veneer manufacturers, and its consumption is expected to grow steadily in the future. It can make full use of artificial fast-growing forests and small and medium-sized logs to produce high value-added products.
LVL can be divided into two broad categories: structural materials (ie load-bearing members) and non-structural materials (ie non-load bearing members). The original structural material LVL was only used for simple beams, and the scope of application is now more and more extensive, such as structural frames, I-beams and other composite products. The main difference between non-structural material LVL and structural material LVL is that it can not be used for load-bearing structures, but only for furniture components, stair components, door and window frames, etc. LVL has various specifications and a wide thickness range. The structural material LVL thickness range is mostly 2-5mm, the maximum thickness can reach 150mm; the width ranges from 100-1800mm; the length ranges from 2500-25000mm, even infinite length. The size of the non-structural material LVL is usually 5 to 50 mm in thickness, 75 to 150 mm in width, and 300 to 600 mm in length. When producing 4" X 8" LVL, plywood can use most of the existing machinery and equipment to generate high-efficiency and flexible LVL products with a small investment.
The structural LVL weight-to-weight ratio is superior to that of steel. The LVL formed by the slab is able to reproduce the characteristics of wood anisotropy to the utmost extent. When the structure is stressed, the longitudinal strength of the wood can be fully utilized. Because the wood itself is thrifty and the veneer cracks are dispersed and evenly distributed in the product, it has uniform mechanical properties, and has the characteristics of uniform quality, stable performance, accurate size and straightness which are unmatched by other structural materials. And easy to process, can be sawed, sliced, chiseled, opened, nailed, etc. After flame retardant treatment, the fire resistance is higher than steel, the weather resistance is good, and the earthquake resistance is strong.
Since the laminated structure of the LVL greatly reduces warpage and distortion of the product, its dimensional and shape stability is good.
The economics of LVL is that it can be laminated and glued with different wood species and different quality raw materials to achieve the value-added effect of large-scale and inferior materials in small villages. It is effective for efficient use of secondary materials such as small-diameter timber, curved wood and short logs. way. The LVL processing technology is mature, the equipment is simple, the production energy consumption is low, the yield is high, the pollution is small, and the production cost is not high. For example, Mingxi County, Fujian Province has rich forest resources, and the county has an annual output of 110,000 cubic meters of commercial materials. Since the production process of LVL is basically similar to that of plywood, the county has built an LVL production line with the artificial board factory as the mother body, making full use of the existing idle equipment, improving the utilization rate of wood, and achieving the combination of forest resource protection and utilization.
LVL is widely used in residential and commercial buildings, as well as in vehicle materials, shipbuilding materials and sleepers. It can be used in a wide range of applications from load-bearing structures to non-load-bearing structures to furniture frames. When used in residential buildings, it can be widely used in houses, structural frames and floor systems. Due to the higher strength-to-weight ratio, the VL is particularly suitable for large-span beams and some areas where wood and steel cannot be easily replaced. LVL not only retains the ideal natural characteristics of wood, but also has the structural features not found in solid wood sawing villages, and its strength far exceeds that of steel roof trusses. In foreign countries, it is widely used in the truss structure of buildings, and can be used for floor coverings, bowling ball boards, container floors, railway sleepers, cement formwork, and the like. In recent years, the demand for LVL in Japan and the Middle East has increased year by year. According to statistics, the global LVL production in 1998 was 2.3 million cubic meters. It is estimated that by 2002, the global consumption of LVL will reach 24 million cubic meters. At present, North America, Japan, Finland, Australia, New Zealand and other countries all produce LVL. Only Shandong Kailin Wood-based Panel Industry Co., Ltd. is producing LVL in China. Therefore, VL materials have good market prospects at home and abroad.
In 1998, China began to ban natural forest cutting, and the demand for wood-based panels in China increased at a rate of 16% per year. It is expected to reach 35 million cubic meters by 2010, especially for wood-based panels and structural panels for construction and decoration. Larger, resulting in a contradiction between wood raw materials and demand, the production of wood-based panels can not meet the needs of the market. China has a large number of artificial fast-growing forest resources that can be developed and utilized within a few years, and architectural design is also in line with international standards. LVL can be produced by small diameter wood, curved wood and short logs, and the yield is about 60% to 70%. Fast-growing materials and thinning materials (pine, poplar, etc.) with a log diameter of about 250 mm are more suitable for the production of LVL. This specification has a large amount of material and is difficult to produce plywood or wood. It is feasible to retrofit existing plywood plants for the production of LVL or to produce plywood and LVL at the same time, especially in areas where fast-growing and high-yield forests are better.
With the deepening of China's reform and opening up and the WTO, people's living standards are constantly improving, and the demand for wood will continue to increase. From the perspective of construction, China's urban and rural residential construction only accounts for 20% of the national total, and it is estimated that by 2010, the total amount of urban and rural construction timber in China will reach 85.5 million m, of which there are many plywoods available. alternatives. In foreign countries, LVL replaces solid wood panels for furniture and construction, and has established corresponding standards. However, China's production and application of LVL is only just beginning or blank. Therefore, the author believes that the active introduction of advanced technology in the country, through the technical transformation of the existing plywood factory to produce LVL, not only has broad market prospects, but also can make China's plywood industry embark on a sustainable development path.
LVL can be divided into two broad categories: structural materials (ie load-bearing members) and non-structural materials (ie non-load bearing members). The original structural material LVL was only used for simple beams, and the scope of application is now more and more extensive, such as structural frames, I-beams and other composite products. The main difference between non-structural material LVL and structural material LVL is that it can not be used for load-bearing structures, but only for furniture components, stair components, door and window frames, etc. LVL has various specifications and a wide thickness range. The structural material LVL thickness range is mostly 2-5mm, the maximum thickness can reach 150mm; the width ranges from 100-1800mm; the length ranges from 2500-25000mm, even infinite length. The size of the non-structural material LVL is usually 5 to 50 mm in thickness, 75 to 150 mm in width, and 300 to 600 mm in length. When producing 4" X 8" LVL, plywood can use most of the existing machinery and equipment to generate high-efficiency and flexible LVL products with a small investment.
The structural LVL weight-to-weight ratio is superior to that of steel. The LVL formed by the slab is able to reproduce the characteristics of wood anisotropy to the utmost extent. When the structure is stressed, the longitudinal strength of the wood can be fully utilized. Because the wood itself is thrifty and the veneer cracks are dispersed and evenly distributed in the product, it has uniform mechanical properties, and has the characteristics of uniform quality, stable performance, accurate size and straightness which are unmatched by other structural materials. And easy to process, can be sawed, sliced, chiseled, opened, nailed, etc. After flame retardant treatment, the fire resistance is higher than steel, the weather resistance is good, and the earthquake resistance is strong.
Since the laminated structure of the LVL greatly reduces warpage and distortion of the product, its dimensional and shape stability is good.
The economics of LVL is that it can be laminated and glued with different wood species and different quality raw materials to achieve the value-added effect of large-scale and inferior materials in small villages. It is effective for efficient use of secondary materials such as small-diameter timber, curved wood and short logs. way. The LVL processing technology is mature, the equipment is simple, the production energy consumption is low, the yield is high, the pollution is small, and the production cost is not high. For example, Mingxi County, Fujian Province has rich forest resources, and the county has an annual output of 110,000 cubic meters of commercial materials. Since the production process of LVL is basically similar to that of plywood, the county has built an LVL production line with the artificial board factory as the mother body, making full use of the existing idle equipment, improving the utilization rate of wood, and achieving the combination of forest resource protection and utilization.
LVL is widely used in residential and commercial buildings, as well as in vehicle materials, shipbuilding materials and sleepers. It can be used in a wide range of applications from load-bearing structures to non-load-bearing structures to furniture frames. When used in residential buildings, it can be widely used in houses, structural frames and floor systems. Due to the higher strength-to-weight ratio, the VL is particularly suitable for large-span beams and some areas where wood and steel cannot be easily replaced. LVL not only retains the ideal natural characteristics of wood, but also has the structural features not found in solid wood sawing villages, and its strength far exceeds that of steel roof trusses. In foreign countries, it is widely used in the truss structure of buildings, and can be used for floor coverings, bowling ball boards, container floors, railway sleepers, cement formwork, and the like. In recent years, the demand for LVL in Japan and the Middle East has increased year by year. According to statistics, the global LVL production in 1998 was 2.3 million cubic meters. It is estimated that by 2002, the global consumption of LVL will reach 24 million cubic meters. At present, North America, Japan, Finland, Australia, New Zealand and other countries all produce LVL. Only Shandong Kailin Wood-based Panel Industry Co., Ltd. is producing LVL in China. Therefore, VL materials have good market prospects at home and abroad.
In 1998, China began to ban natural forest cutting, and the demand for wood-based panels in China increased at a rate of 16% per year. It is expected to reach 35 million cubic meters by 2010, especially for wood-based panels and structural panels for construction and decoration. Larger, resulting in a contradiction between wood raw materials and demand, the production of wood-based panels can not meet the needs of the market. China has a large number of artificial fast-growing forest resources that can be developed and utilized within a few years, and architectural design is also in line with international standards. LVL can be produced by small diameter wood, curved wood and short logs, and the yield is about 60% to 70%. Fast-growing materials and thinning materials (pine, poplar, etc.) with a log diameter of about 250 mm are more suitable for the production of LVL. This specification has a large amount of material and is difficult to produce plywood or wood. It is feasible to retrofit existing plywood plants for the production of LVL or to produce plywood and LVL at the same time, especially in areas where fast-growing and high-yield forests are better.
With the deepening of China's reform and opening up and the WTO, people's living standards are constantly improving, and the demand for wood will continue to increase. From the perspective of construction, China's urban and rural residential construction only accounts for 20% of the national total, and it is estimated that by 2010, the total amount of urban and rural construction timber in China will reach 85.5 million m, of which there are many plywoods available. alternatives. In foreign countries, LVL replaces solid wood panels for furniture and construction, and has established corresponding standards. However, China's production and application of LVL is only just beginning or blank. Therefore, the author believes that the active introduction of advanced technology in the country, through the technical transformation of the existing plywood factory to produce LVL, not only has broad market prospects, but also can make China's plywood industry embark on a sustainable development path.
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