1.4 Finger joint material quality assessment and inspection
1.4.1 Quality assessment National standard GB11954-89 "finger-joined materials" stipulates that the quality assessment of finger-joined materials is divided into three categories: excellent products, first-class products and qualified products.
1.4.2 Inspection of national standards GB11954-89 "finger-joined materials" Chapter 8 specifies the inspection rules for finger-joined materials, which must be followed. The two main objectives of quality management are to anticipate sub-standard products and prevent them from being put into use, and to identify the cause of the problem, to correct or resolve it. Quality control procedures should include visual inspection, direct measurement of selected variables, and selection of samples for physical testing. Visual inspection and selection of variable measurements during processing to prevent or minimize unacceptable products. The physical test after the product is manufactured is a re-examination of the visual inspection, measurement and control process. Finger joint testing can be divided into two types, broken and non-destructive. For damage detection, samples are intermittently selected from the production process and then loaded to failure (variation, compression, tensile, impact toughness, etc.). Compare the intensity of the damage to the minimum value specified by the national standard. After the test, the damage state, position and wood destruction rate of the finger-joined wood which were visually fractured were analyzed and compared. The static test is usually a quick and easy way to detect the quality of the finger joint. In recent years, with the advancement and development of science and technology, non-destructive testing has received more and more attention. There are mainly ultrasonic detectors and stress detectors. Washington State University has conducted a series of studies on wood non-destructive testing (non-destructive testing). Researchers at the Woodworking Institute of the Chinese Academy of Forestry have also conducted research. The test load method is another method of testing or evaluating finger joint quality and has now received attention. In the test load test, the finger joints are subjected to a stress large enough to indicate their ability to withstand the design load. In the production of finger joints for structural use, the test device can be used to detect each finger-joined wood product one by one, and the product that does not meet the standard minimum strength value is removed, so that the finger joint wood used in the engineering structure is safe. Reliability is guaranteed. In the production of large-scale finger-joined wood, non-destructive testing such as gluing girders guarantees the quality of the product and avoids the loss caused by the damage of the product. It is a promising test method.
2 Glulam production process and equipment
2.1 Glulam production process The material is defined as wood that is parallel to the fiber direction along the fiber direction and glued in thickness, width and length.
2.1.1 Types of Glulam The types of Glulam are divided into two categories according to their use: structural glulam and non-structural glulam. The structural glulam is used as a load-bearing member such as a beam, a column, or the like. Therefore, its physical and mechanical properties, such as tensile strength, tensile strength, elastic modulus, weather resistance, etc. have certain requirements, from raw materials, adhesives, production processes to product testing and other non-structural laminated materials. Non-structural composite materials for non-load-bearing or semi-load-bearing applications, mainly used for interior decoration and high-end furniture.
2.1.2 Commonly used coniferous species Commonly used in the tree species are Korean pine, larch, spruce, Yunnan pine, cypress and so on. Commonly used broad-leaved tree species include ash, eucalyptus, eucalyptus, sapwood, medlar, eucalyptus, red peony, and nanmu. The type of wood used as the raw material for the laminated timber is mainly determined by the degree of market customers' preference, the recognized selling price and the amount of resources available. At present, the Japanese market prefers the northeastern elm and ash, and the market prefers beech, beech, and walnut. Therefore, the integrated material manufacturer should select the tree species according to the above two factors. There are many integrated tree species suitable for the production of decoration in the south of China. However, because a fashion is not accepted by customers and the quantity is small, the distribution is not concentrated, and it is difficult to form large-scale production, which is not fully utilized.
21.3 Glulam manufacturing process logs→materials→plate drying naturally→plate kiln drying→plate two-side planing→plate multi-saw parts→strip cutting defects→strips on both ends of the slats→finger squeegee→slats Length finger joint → finger joint slats four sides planing → matching board → glued → group fight → cold pressure curing → planing light → head → sanding → inspection points → finished product packaging repair → storage 2.1.4 Adhesives used in adhesives for laminated materials, whether finger-joined or laminated, are room temperature-curing phenolic (PF) resin glues and phenol-resorcinol-formaldehyde (PRF) resin glues. Adhesives commonly used for non-structural laminated materials: finger-jointed white latex, ie polyvinyl acetate emulsion (PVAC) or modified water-resistant white latex. The glue is made of water-soluble isocyanate resin glue, which is characterized by short curing time at room temperature (20 to 30 minutes), high strength, no brittle and hard layer, and less wear on the tool. Urea-formaldehyde (UF) resin is not suitable for the bonding of laminated materials.
2.1.5 Product Standards and Main Test Indicators of Glulam At present, China has not yet formulated national standards and professional standards for glulam, and only the respective enterprise standards of production companies. This undoubtedly brings inconvenience to the production and development of laminated materials. In foreign countries, such as Japan, Britain, the United States, Canada and other European and American countries have formulated relevant standards. At present, the enterprise standards of domestic production enterprises stipulate the material defects of the laminated materials and its moisture content, test methods and indicators of the peeling rate of the rubber layer.
2.2 Glulam production equipment
2.2.1 Large and small band saws for main equipment and materials; drying kiln for drying plates; double-sided planer for multi-face sawing, multi-blade circular sawing machine, cross-cut saw, finger-opening machine, gluing machine, finger Pick-up machine, four-sided planer; four-roller coating machine for processing integrated materials, cold-pressing glue machine, wide-face pressing, wide-band sanding machine, trimming machine, etc.
2.2.2 Auxiliary equipment sharpening machine, sawing machine, various transportation equipment and devices, balers, etc. At present, the main equipment for the manufacture of laminated timber by domestic manufacturers is imported from Japan, Germany, Italy, and Taiwan, and non-critical equipment is supported by domestic products.
2.3 Precautions for the production of laminated timber
2.3.1 Production scale and original basic conditions The production scale shall be determined according to various factors such as the respective funds, raw material supply, product market, transportation and other factors. In the current stage, the annual output is 1000-2000 m3. If the technical transformation is carried out on the basis of the original wood factory, adding the necessary key equipment for conversion, you can receive the benefits of less investment, short cycle and quick effect. 2.3.2 The equipment is selected from domestic and foreign, and the performance of saving foreign equipment is better than that of domestic equipment, but the price of foreign equipment is often several times that of domestic equipment. In addition, the spare parts of imported equipment are insufficient, the cost of re-importing in the future is too high, and the technical mastery and maintenance ability of imported equipment, etc., often good equipment may not be able to exert good benefits.
2.3.2 Comprehensive utilization must be carried out, and various operations should be carried out to improve the utilization rate of wood. At present, the production rate of laminated timber produced by domestic enterprises is only 12% to 15%. Although the price of laminated timber is very high, the cost is more due to the consumption of logs. Too high results in poor economic returns. Therefore, it is necessary to carry out comprehensive utilization of the processing residues of the production of the laminated timber.
2.3.3 Strengthen management, improve technical level, strictly control quality, improve product quality and quality. The price of laminated materials is double the quality. Therefore, in order to obtain better economic benefits, we must improve product quality.
2.3.5 Use local resources and domestic raw materials to actively develop the domestic market and actively develop China's integrated timber production to make full use of China's forest resources. The selected wood species should not be limited to a few species of ash, eucalyptus, etc. There are many coniferous and broad-leaved species suitable for the production of assemblages in the south of the Yangtze River Basin in China. In addition, the adhesive in the excipients has also been successfully developed in China, and its performance is comparable to that of Japanese products. Finger-shaped milling cutters, domestically produced, can basically meet the accuracy requirements, and their prices are much lower than imported goods, and do not have to rely entirely on imports. At present, with the development of the national economy and the improvement of people's living standards, furniture made of laminated timber, although sold at a higher price, has begun to be accepted by the nationals. Interior decoration is getting more and more prosperous, and the use of laminated timber for decoration will be gradually popularized as in foreign countries. Therefore, the domestic market for laminated timber also has good prospects.
1.4.1 Quality assessment National standard GB11954-89 "finger-joined materials" stipulates that the quality assessment of finger-joined materials is divided into three categories: excellent products, first-class products and qualified products.
1.4.2 Inspection of national standards GB11954-89 "finger-joined materials" Chapter 8 specifies the inspection rules for finger-joined materials, which must be followed. The two main objectives of quality management are to anticipate sub-standard products and prevent them from being put into use, and to identify the cause of the problem, to correct or resolve it. Quality control procedures should include visual inspection, direct measurement of selected variables, and selection of samples for physical testing. Visual inspection and selection of variable measurements during processing to prevent or minimize unacceptable products. The physical test after the product is manufactured is a re-examination of the visual inspection, measurement and control process. Finger joint testing can be divided into two types, broken and non-destructive. For damage detection, samples are intermittently selected from the production process and then loaded to failure (variation, compression, tensile, impact toughness, etc.). Compare the intensity of the damage to the minimum value specified by the national standard. After the test, the damage state, position and wood destruction rate of the finger-joined wood which were visually fractured were analyzed and compared. The static test is usually a quick and easy way to detect the quality of the finger joint. In recent years, with the advancement and development of science and technology, non-destructive testing has received more and more attention. There are mainly ultrasonic detectors and stress detectors. Washington State University has conducted a series of studies on wood non-destructive testing (non-destructive testing). Researchers at the Woodworking Institute of the Chinese Academy of Forestry have also conducted research. The test load method is another method of testing or evaluating finger joint quality and has now received attention. In the test load test, the finger joints are subjected to a stress large enough to indicate their ability to withstand the design load. In the production of finger joints for structural use, the test device can be used to detect each finger-joined wood product one by one, and the product that does not meet the standard minimum strength value is removed, so that the finger joint wood used in the engineering structure is safe. Reliability is guaranteed. In the production of large-scale finger-joined wood, non-destructive testing such as gluing girders guarantees the quality of the product and avoids the loss caused by the damage of the product. It is a promising test method.
2 Glulam production process and equipment
2.1 Glulam production process The material is defined as wood that is parallel to the fiber direction along the fiber direction and glued in thickness, width and length.
2.1.1 Types of Glulam The types of Glulam are divided into two categories according to their use: structural glulam and non-structural glulam. The structural glulam is used as a load-bearing member such as a beam, a column, or the like. Therefore, its physical and mechanical properties, such as tensile strength, tensile strength, elastic modulus, weather resistance, etc. have certain requirements, from raw materials, adhesives, production processes to product testing and other non-structural laminated materials. Non-structural composite materials for non-load-bearing or semi-load-bearing applications, mainly used for interior decoration and high-end furniture.
2.1.2 Commonly used coniferous species Commonly used in the tree species are Korean pine, larch, spruce, Yunnan pine, cypress and so on. Commonly used broad-leaved tree species include ash, eucalyptus, eucalyptus, sapwood, medlar, eucalyptus, red peony, and nanmu. The type of wood used as the raw material for the laminated timber is mainly determined by the degree of market customers' preference, the recognized selling price and the amount of resources available. At present, the Japanese market prefers the northeastern elm and ash, and the market prefers beech, beech, and walnut. Therefore, the integrated material manufacturer should select the tree species according to the above two factors. There are many integrated tree species suitable for the production of decoration in the south of China. However, because a fashion is not accepted by customers and the quantity is small, the distribution is not concentrated, and it is difficult to form large-scale production, which is not fully utilized.
21.3 Glulam manufacturing process logs→materials→plate drying naturally→plate kiln drying→plate two-side planing→plate multi-saw parts→strip cutting defects→strips on both ends of the slats→finger squeegee→slats Length finger joint → finger joint slats four sides planing → matching board → glued → group fight → cold pressure curing → planing light → head → sanding → inspection points → finished product packaging repair → storage 2.1.4 Adhesives used in adhesives for laminated materials, whether finger-joined or laminated, are room temperature-curing phenolic (PF) resin glues and phenol-resorcinol-formaldehyde (PRF) resin glues. Adhesives commonly used for non-structural laminated materials: finger-jointed white latex, ie polyvinyl acetate emulsion (PVAC) or modified water-resistant white latex. The glue is made of water-soluble isocyanate resin glue, which is characterized by short curing time at room temperature (20 to 30 minutes), high strength, no brittle and hard layer, and less wear on the tool. Urea-formaldehyde (UF) resin is not suitable for the bonding of laminated materials.
2.1.5 Product Standards and Main Test Indicators of Glulam At present, China has not yet formulated national standards and professional standards for glulam, and only the respective enterprise standards of production companies. This undoubtedly brings inconvenience to the production and development of laminated materials. In foreign countries, such as Japan, Britain, the United States, Canada and other European and American countries have formulated relevant standards. At present, the enterprise standards of domestic production enterprises stipulate the material defects of the laminated materials and its moisture content, test methods and indicators of the peeling rate of the rubber layer.
2.2 Glulam production equipment
2.2.1 Large and small band saws for main equipment and materials; drying kiln for drying plates; double-sided planer for multi-face sawing, multi-blade circular sawing machine, cross-cut saw, finger-opening machine, gluing machine, finger Pick-up machine, four-sided planer; four-roller coating machine for processing integrated materials, cold-pressing glue machine, wide-face pressing, wide-band sanding machine, trimming machine, etc.
2.2.2 Auxiliary equipment sharpening machine, sawing machine, various transportation equipment and devices, balers, etc. At present, the main equipment for the manufacture of laminated timber by domestic manufacturers is imported from Japan, Germany, Italy, and Taiwan, and non-critical equipment is supported by domestic products.
2.3 Precautions for the production of laminated timber
2.3.1 Production scale and original basic conditions The production scale shall be determined according to various factors such as the respective funds, raw material supply, product market, transportation and other factors. In the current stage, the annual output is 1000-2000 m3. If the technical transformation is carried out on the basis of the original wood factory, adding the necessary key equipment for conversion, you can receive the benefits of less investment, short cycle and quick effect. 2.3.2 The equipment is selected from domestic and foreign, and the performance of saving foreign equipment is better than that of domestic equipment, but the price of foreign equipment is often several times that of domestic equipment. In addition, the spare parts of imported equipment are insufficient, the cost of re-importing in the future is too high, and the technical mastery and maintenance ability of imported equipment, etc., often good equipment may not be able to exert good benefits.
2.3.2 Comprehensive utilization must be carried out, and various operations should be carried out to improve the utilization rate of wood. At present, the production rate of laminated timber produced by domestic enterprises is only 12% to 15%. Although the price of laminated timber is very high, the cost is more due to the consumption of logs. Too high results in poor economic returns. Therefore, it is necessary to carry out comprehensive utilization of the processing residues of the production of the laminated timber.
2.3.3 Strengthen management, improve technical level, strictly control quality, improve product quality and quality. The price of laminated materials is double the quality. Therefore, in order to obtain better economic benefits, we must improve product quality.
2.3.5 Use local resources and domestic raw materials to actively develop the domestic market and actively develop China's integrated timber production to make full use of China's forest resources. The selected wood species should not be limited to a few species of ash, eucalyptus, etc. There are many coniferous and broad-leaved species suitable for the production of assemblages in the south of the Yangtze River Basin in China. In addition, the adhesive in the excipients has also been successfully developed in China, and its performance is comparable to that of Japanese products. Finger-shaped milling cutters, domestically produced, can basically meet the accuracy requirements, and their prices are much lower than imported goods, and do not have to rely entirely on imports. At present, with the development of the national economy and the improvement of people's living standards, furniture made of laminated timber, although sold at a higher price, has begun to be accepted by the nationals. Interior decoration is getting more and more prosperous, and the use of laminated timber for decoration will be gradually popularized as in foreign countries. Therefore, the domestic market for laminated timber also has good prospects.
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