Non-structural laminated timber (hereinafter referred to as laminated timber) is a kind of furniture and interior decoration materials. It is made by dividing the short wood of the wood defects (fruits, resin, decay, etc.) into a certain length and then widening horizontally (or Glued together. Because the integrated material eliminates wood defects, it does not change the structure and characteristics of the wood itself, so it is still a kind of natural wood. It not only has the texture of natural wood, but also has beautiful appearance, uniform material, and overcomes the tendency of natural wood to warp. Deformed and cracked people have better tensile and compressive strength than natural wood, and are a new type of board that is irreplaceable for wood-based panels. What's more important is that it is really used for small materials and excellent materials. It makes full use of the factory to add surplus waste and fast-growing small-diameter materials, which improves the comprehensive utilization rate and added value of wood, and can effectively alleviate the contradiction between supply and demand of wood resources. A green and environmentally friendly material.
Glulam is mainly used for furniture, stairs, handrails, doors and windows and interior decoration components, and is very popular internationally. The high-grade furniture with integrated materials not only looks beautiful, but also is durable and popular among consumers. Therefore, the export of laminated materials has broad market prospects. The application of glulam technology in China began in the early 1960s, but its development is slow. It still occupies only the level of small-volume production of surplus waste. At present, the annual output of national integrated timber is only 4-5 million m3. Can not meet the needs of use, compared with developed countries, there is also a big gap, the main raw materials for the production of laminated timber, small-diameter materials have not been effectively developed and utilized in China. China's forest coverage is low, the amount of wood storage is small, and the contradiction between supply and demand of high-quality wood at large diameter is very prominent. Therefore, mass production of high-quality laminated timber is an effective way to make full use of the remaining waste and improve the comprehensive utilization and added value of small-diameter wood. way.
In order to ensure the scale, efficiency, finger joint length, precision and rubber strength of the integrated production, it is necessary to introduce advanced, mechanized automation equipment. Some existing enterprises in China have introduced some advanced integrated production lines, but most of them have not been fully utilized, and have not formed a certain scale of production, processing technology is not mature, and processing quality is unstable. This paper proposes some process technologies for the processing of integrated materials for the reference of manufacturers of integrated materials.
1 Quality standard
1.1 Wood species
Larch, ash, eucalyptus, elm, poplar, fir, spruce, oak, rubberwood, etc.
1.2 Material
If the material of the laminated material is too high, it will affect the yield of the product. If it is too low, it will affect the quality of the product. According to the actual production situation in China, the following table is formulated with reference to relevant foreign standards for reference.
Note: The defects of 1 knot, decay, resin and other defects can be repaired and repaired, the maximum gap is ±0.2mm, and the number of repairs is 5/m2.
2 Product specifications and dimensions are determined as required. Dimensional tolerance: thickness 1.0mm, length tolerance is not limited, negative tolerance is 0.
1.3 Moisture content
The moisture content of wood is one of the main factors affecting the defects such as open glue, end crack and warpage of laminated materials. The moisture content is too high and the bonding strength is low; while the moisture content is too low, the moisture in the adhesive is quickly absorbed by the wood and the adhesion is also poor. Generally, wood moisture content is required to be 8%-12%, and the moisture content difference between adjacent wood strips cannot exceed ±2%. Therefore, the wood must pass the high-quality drying treatment, and it is required to be placed in the dry plate library for more than half a month to eliminate the dry stress and make the water content uniform.
1.4 Water resistance
The laminated material sample was immersed in water at room temperature for 6 hours, and dried in a constant temperature drying oven at 40 ° C for 18 hours. The peeling rate of the rubber joint should be less than 10%, and the peeling length of the same rubber joint should be less than 1/3 of the total length of the rubber joint.
2 Process technology
2.1 Production process
Material → Drying → Longitudinal planing of double-sided planing of the board → Elimination of defects → finger joints → slat planing and coating → widening → flat surface planing (coating, thickening, final processing).
2.2 Wood drying
The production of laminated timber by processing surplus waste should strictly control the moisture content of the waste to meet the requirements of water content. If small diameter material is used for production, due to shrinkage, swelling, cracking and deformation of small diameter material, cracking and deformation are easy to occur during drying. Therefore, the edge board after sawing can be “boiled→naturally dried→low temperature artificial dryingâ€. The treatment process is firstly boiled in hot water at 90 ° C for 2 h to make the edge and heartwood moisture content uniform, eliminate internal stress, and leaching resin components. Then, it is naturally dried to a moisture content of 40% or less, and then dried at a temperature of 55 ° C for 48-72 hours to obtain a moisture content of 8% to 12%.
2.3 Integrated material processing
2.3.1 Finger joint processing Finger joints include four processes of gingival processing, gluing, pressure gluing and fixed length cutting. According to the number of processes completed on one machine, the finger-joining machine has two kinds of processing methods: single machine and automatic machine. Figure 1 shows a structural form of a finger-joined automated machine. The processing sequence is: 1 feeding the wood into the machine by the feeding roller; 2 pressing the wood with the pressure plate; 3 lowering the horizontal axis, performing the gingival processing; 4 cutting the shaft; 5 applying the glue by the glue coating device (spraying or brushing); 6 movable table moves, presses the gums; 7 presses up; 8 returns the workbench; 9 moves the wood after fingering; 10 fixed length cut off.
2.3.2 The widening and widening is to process the finger-joined slats into a plate-shaped laminated material through three processes: planing, gluing and pressure gluing. The special machine for widening has a multi-layer hot press and a jigsaw machine (the jigsaw machine can be divided into a hot plate type jigsaw machine and a rotary jigsaw machine, and the hot plate jigsaw machine has a longitudinal direction according to the slat entry mode. Feed and cross feed two forms). The multi-layer hot press is shown in Figure 2. The processing sequence is as follows: (1) the glued slats are placed on the workbench with the slabs, and then sent to the hot press by the plate loading machine; 2 the hot platen is closed. , the pressure is 1-2kg/cm2; 3 is applied by the hydraulic cylinder with a lateral pressure of 7-8kg/cm2; 4 is the heat conduction of the hot plate to solidify the glue; 5 is to relieve the lateral pressure, the hot plate is lowered; Take out the product.
The rotary jigsaw machine is composed of a plurality of metal clamps on the conveyor chain, and the glue imposition blank is clamped in the clamp (the clamping device is driven by the motor or the hydraulic cylinder), and the transmission chain is rotated by the motor, each After one week, the glue in the panel is solidified and can be removed from the clamp and replaced with another piece. In order to speed up the bonding speed, a heater can be added under the conveyor chain. The rotary type jigsaw machine is used for widening, high production efficiency, and can be used for large panels. The use of fast curing glue such as water-soluble vinyl polyurethane glue can further improve production efficiency.
2.3.3 Thickness Sometimes the thickness of the laminated board that needs to be processed according to the need also needs to be thickened. The thickening includes the steps of flattening, gluing and pressure gluing. The flattening of the plate can be double-sided planing, and the thickening is more by spiral pressing device, hydraulic pressing device and cold pressing machine.
2.4 Finger joint process parameters
2.4.1 The tooth length is 10-40mm, and the mechanical properties are enhanced with the increase of the tooth length, and the slope is 1/8-1/10.
2.4.2 Glue non-structural integration materials are urea-formaldehyde glue, milk white glue, water-based polyurethane glue and so on. Coating amount: 200-300g/m2.
2.4.3 Gum glue temperature at room temperature, gluing pressure: 8Mpa, gluing time: 5S, Chen time: 24h.
2.4.4 Planed light is connected to the wooden strips and then planed on all sides. No defects such as planing corrugations or hoes are allowed.
2.4.5 When the glue width is widened, the above rubber type can be used, the glue amount is 200-300g/m2, the glue pressure temperature is normal temperature, the pressure is 0.7-1.0Mpa, the pressure holding time is 1-2h, and the time is over 48h.
Finally, the flat plate will be flattened, planed and planed (sometimes also need to be thickly processed), which is the finished product of finger jointing, which can be used as high-grade furniture parts and interior materials for tables and countertops. .
Glulam is mainly used for furniture, stairs, handrails, doors and windows and interior decoration components, and is very popular internationally. The high-grade furniture with integrated materials not only looks beautiful, but also is durable and popular among consumers. Therefore, the export of laminated materials has broad market prospects. The application of glulam technology in China began in the early 1960s, but its development is slow. It still occupies only the level of small-volume production of surplus waste. At present, the annual output of national integrated timber is only 4-5 million m3. Can not meet the needs of use, compared with developed countries, there is also a big gap, the main raw materials for the production of laminated timber, small-diameter materials have not been effectively developed and utilized in China. China's forest coverage is low, the amount of wood storage is small, and the contradiction between supply and demand of high-quality wood at large diameter is very prominent. Therefore, mass production of high-quality laminated timber is an effective way to make full use of the remaining waste and improve the comprehensive utilization and added value of small-diameter wood. way.
In order to ensure the scale, efficiency, finger joint length, precision and rubber strength of the integrated production, it is necessary to introduce advanced, mechanized automation equipment. Some existing enterprises in China have introduced some advanced integrated production lines, but most of them have not been fully utilized, and have not formed a certain scale of production, processing technology is not mature, and processing quality is unstable. This paper proposes some process technologies for the processing of integrated materials for the reference of manufacturers of integrated materials.
1 Quality standard
1.1 Wood species
Larch, ash, eucalyptus, elm, poplar, fir, spruce, oak, rubberwood, etc.
1.2 Material
If the material of the laminated material is too high, it will affect the yield of the product. If it is too low, it will affect the quality of the product. According to the actual production situation in China, the following table is formulated with reference to relevant foreign standards for reference.
Note: The defects of 1 knot, decay, resin and other defects can be repaired and repaired, the maximum gap is ±0.2mm, and the number of repairs is 5/m2.
2 Product specifications and dimensions are determined as required. Dimensional tolerance: thickness 1.0mm, length tolerance is not limited, negative tolerance is 0.
1.3 Moisture content
The moisture content of wood is one of the main factors affecting the defects such as open glue, end crack and warpage of laminated materials. The moisture content is too high and the bonding strength is low; while the moisture content is too low, the moisture in the adhesive is quickly absorbed by the wood and the adhesion is also poor. Generally, wood moisture content is required to be 8%-12%, and the moisture content difference between adjacent wood strips cannot exceed ±2%. Therefore, the wood must pass the high-quality drying treatment, and it is required to be placed in the dry plate library for more than half a month to eliminate the dry stress and make the water content uniform.
1.4 Water resistance
The laminated material sample was immersed in water at room temperature for 6 hours, and dried in a constant temperature drying oven at 40 ° C for 18 hours. The peeling rate of the rubber joint should be less than 10%, and the peeling length of the same rubber joint should be less than 1/3 of the total length of the rubber joint.
2 Process technology
2.1 Production process
Material → Drying → Longitudinal planing of double-sided planing of the board → Elimination of defects → finger joints → slat planing and coating → widening → flat surface planing (coating, thickening, final processing).
2.2 Wood drying
The production of laminated timber by processing surplus waste should strictly control the moisture content of the waste to meet the requirements of water content. If small diameter material is used for production, due to shrinkage, swelling, cracking and deformation of small diameter material, cracking and deformation are easy to occur during drying. Therefore, the edge board after sawing can be “boiled→naturally dried→low temperature artificial dryingâ€. The treatment process is firstly boiled in hot water at 90 ° C for 2 h to make the edge and heartwood moisture content uniform, eliminate internal stress, and leaching resin components. Then, it is naturally dried to a moisture content of 40% or less, and then dried at a temperature of 55 ° C for 48-72 hours to obtain a moisture content of 8% to 12%.
2.3 Integrated material processing
2.3.1 Finger joint processing Finger joints include four processes of gingival processing, gluing, pressure gluing and fixed length cutting. According to the number of processes completed on one machine, the finger-joining machine has two kinds of processing methods: single machine and automatic machine. Figure 1 shows a structural form of a finger-joined automated machine. The processing sequence is: 1 feeding the wood into the machine by the feeding roller; 2 pressing the wood with the pressure plate; 3 lowering the horizontal axis, performing the gingival processing; 4 cutting the shaft; 5 applying the glue by the glue coating device (spraying or brushing); 6 movable table moves, presses the gums; 7 presses up; 8 returns the workbench; 9 moves the wood after fingering; 10 fixed length cut off.
2.3.2 The widening and widening is to process the finger-joined slats into a plate-shaped laminated material through three processes: planing, gluing and pressure gluing. The special machine for widening has a multi-layer hot press and a jigsaw machine (the jigsaw machine can be divided into a hot plate type jigsaw machine and a rotary jigsaw machine, and the hot plate jigsaw machine has a longitudinal direction according to the slat entry mode. Feed and cross feed two forms). The multi-layer hot press is shown in Figure 2. The processing sequence is as follows: (1) the glued slats are placed on the workbench with the slabs, and then sent to the hot press by the plate loading machine; 2 the hot platen is closed. , the pressure is 1-2kg/cm2; 3 is applied by the hydraulic cylinder with a lateral pressure of 7-8kg/cm2; 4 is the heat conduction of the hot plate to solidify the glue; 5 is to relieve the lateral pressure, the hot plate is lowered; Take out the product.
The rotary jigsaw machine is composed of a plurality of metal clamps on the conveyor chain, and the glue imposition blank is clamped in the clamp (the clamping device is driven by the motor or the hydraulic cylinder), and the transmission chain is rotated by the motor, each After one week, the glue in the panel is solidified and can be removed from the clamp and replaced with another piece. In order to speed up the bonding speed, a heater can be added under the conveyor chain. The rotary type jigsaw machine is used for widening, high production efficiency, and can be used for large panels. The use of fast curing glue such as water-soluble vinyl polyurethane glue can further improve production efficiency.
2.3.3 Thickness Sometimes the thickness of the laminated board that needs to be processed according to the need also needs to be thickened. The thickening includes the steps of flattening, gluing and pressure gluing. The flattening of the plate can be double-sided planing, and the thickening is more by spiral pressing device, hydraulic pressing device and cold pressing machine.
2.4 Finger joint process parameters
2.4.1 The tooth length is 10-40mm, and the mechanical properties are enhanced with the increase of the tooth length, and the slope is 1/8-1/10.
2.4.2 Glue non-structural integration materials are urea-formaldehyde glue, milk white glue, water-based polyurethane glue and so on. Coating amount: 200-300g/m2.
2.4.3 Gum glue temperature at room temperature, gluing pressure: 8Mpa, gluing time: 5S, Chen time: 24h.
2.4.4 Planed light is connected to the wooden strips and then planed on all sides. No defects such as planing corrugations or hoes are allowed.
2.4.5 When the glue width is widened, the above rubber type can be used, the glue amount is 200-300g/m2, the glue pressure temperature is normal temperature, the pressure is 0.7-1.0Mpa, the pressure holding time is 1-2h, and the time is over 48h.
Finally, the flat plate will be flattened, planed and planed (sometimes also need to be thickly processed), which is the finished product of finger jointing, which can be used as high-grade furniture parts and interior materials for tables and countertops. .
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Kumusi (Dongguan) Furniture Co., Ltd. , https://www.kcoffeetable.com