Artificial wood is a kind of natural precious tree wood which is made of rotary cutting (or sliced) veneer of plantation or common tree species, which is made by single board bleaching, dyeing, layering and gluing. A new wooden decorative material with texture, pattern and hue, or other artistic patterns. It can be processed differently according to different needs, so as to get different products, such as wood, sawn timber, thin wood and so on.
Artificial wood has all the good characteristics of natural wood. At the same time, it has many advantages compared with natural wood: (1) products made from natural wood are generally limited by the diameter of the logs, small in size and size, and artificial wood. It can be made into various specifications according to needs, which simplifies the production process and helps to achieve continuous production. (2) Since the texture and color tone of artificial wood can be artificially controlled, it can imitate various natural precious woods. It produces textures and shades that natural wood does not have. It is more colorful than natural wood. Moreover, artificial wood can remove some natural defects of natural wood such as dead knots and discoloration during the production process. Therefore, compared with natural wood, Artificial wood can better meet people's individual requirements; (3) natural wood is affected by the diameter of logs, and the yield is lower than that of artificial wood; and artificial wood has low requirements for raw materials, and the source of raw materials is wide. low. Therefore, artificial wood can not only ease the contradiction between supply and demand, but also achieve superior use of inferior materials. It is a real green environmental protection material with great development space and development necessity.
2. Research history and current situation of artificial wood
As early as the 1960s, Japan, Italy and other countries began to develop and produce artificial wood. Due to the relatively early start, the development of manufacturing technology is relatively fast. In the 1970s, Italy took the lead in realizing industrial production, and then it developed rapidly and went global.
The development of artificial wood in China began in the early 1980s, and it started relatively late, and the development of manufacturing technology is also relatively slow. Compared with foreign countries, there is a big gap in production technology, production equipment, research depth and breadth. . In the mid-1980s, China's southern coastal cities set off a man-made decorative thin wood heat, mainly imported artificial wood from abroad, shaved into thin wood, veneer made into decorative panels for sale, due to its variety of colors, products are in short supply, some manufacturers and Research institutes began to develop artificial wood by themselves and made some progress.
The production process of artificial wood is generally: selection of logs → truncation → softening treatment → veneer cutting → bleaching treatment → dyeing treatment → drying → gluing → blanking → wood molding → four sides correction → four sides sealing → according to different needs Made into different products (such as thin wood, planed wood, sawn timber, etc.). In the production of artificial wood, there are several key technical issues: veneer dyeing, texture simulation, and thin planing and veneering techniques for artificial veneer. These are important reasons for the large-scale mass production of artificial wood. Therefore, in recent years, research on artificial wood at home and abroad has focused on these aspects, and great progress has been made.
2.1 veneer dyeing
Since the veneers made of ordinary tree species do not have the texture and color of precious wood, it is necessary to produce bleaching, decolorizing and dyeing the raw material veneers by producing artificial wood similar to the natural luster wood color texture. The application of wood dyeing technology began in the 1970s and began to produce dyed veneers in Italy. In recent years, domestic and foreign scholars have done a lot of research work on dyeing. Based on the research on wood dyeing theory and application technology, Tianyue Village has carried out research on the technical system of uniform coloration, pattern coloration, emphasis on wood ray coloring and multicolor coloration on wood surface. In China, Chen Yuhe and Lu Renshu made a systematic and in-depth study on the dyeing technology of paulownia veneer. The selection of the process parameters of paulownia veneer dyeing, the influence of paulownia veneer dyeing factors on the dyeing rate, and the influence on chromatic aberration were discussed. The process of dyeing the paulownia veneer imitation mahogany was explored. Yu Zhiming et al. used acid dyes for the wood veneer of broadleaf tree species such as Populus tomentosa and Paulownia. The results showed that the acid dye used in the textile industry can be used for wood dyeing, or it can be mixed with several dyes; different treatments before wood dyeing The method affects the dyeing effect of wood; the degree of deformation of dyed veneers is quite different, and the flatness is related to the density of wood; the dye concentration, dyeing time and dyeing temperature have a great influence on the dyeing effect, and the veneers of different tree species should be different. Process. There are also many scholars who have done research on the veneer dyeing of imitation precious wood. For example, using common tree species imitation mahogany, black walnut, rosewood, etc., all have better process parameters.
Veneer dyeing is a relatively complex process involving wood science, dye chemistry, optics, color science, etc. It is an interdisciplinary technology. At present, with the continuous deepening of exchanges between disciplines, the application of computer color matching technology commonly used in textile printing and dyeing industry to wood dyeing has achieved good results. The computer color matching is the best color matching scheme given by the computer color matching after measuring the reflection (transmission) spectrum of the color "standard sample" by the color measuring instrument using modern color theory and computer information technology. Compared with artificial color matching, it has the advantages of agile color, good orientation and high color matching precision. At present, computer color matching is mainly used in the field of wood processing for continuous cylinder filling, dye selection, and concentration calculation.
2.2 Simulation of texture
The pattern of the artificial wood is determined by the laminated form and the cutting angle of the veneer. Therefore, in order to obtain a good simulation effect, it must be carefully considered before the bundling. The pattern of artificial wood is roughly divided into two types: radial pattern and chord pattern.
Radial patterns are commonly found with equally spaced strip-like texture combinations, non-equally spaced strip-like texture combinations, random strip-like texture combinations, and teak-type strip-like texture combinations. The equal-space strip-like texture combination is to arrange two dark and light-colored veneers of the same thickness at intervals, and the thickness of the veneers can be selected according to requirements. The non-equal spacing strip texture combination is to arrange the dark and light colored veneers regularly, but the thickness of the veneers changes periodically. The random strip texture combination is a random arrangement of boards of different colors and different thicknesses without any regularity. The teak-like strip texture combination is a combination of different veneer arrangements that resemble the radial texture of teak. This texture is very similar to the natural teak texture, commonly known as artificial teak.
The chord-to-texture combination is to stack the veneers in a light color and a dark pattern. The light-colored veneers simulate the early wood parts of the wood, and the dark veneers simulate the late wood parts of the wood. The thickness of the dark veneer is thick, and after the veneer is laminated, the curved shape is pressed into a curved wood mold, and the artificial string is obtained by cutting according to a certain cutting angle. To create a chord pattern, it must pay attention to and have the following conditions: First, the light color veneer is used to simulate the early wood part of the wood, and the dark veneer or dyed veneer is used, and the adjuster color adhesive is used to simulate the late wood part; Design and manufacture molds of different shapes (compression molds); third, use a certain angle to intersect the curved surface.
At present, the simulation technology of radial pattern has been relatively mature, and most of the research on texture simulation focuses on the simulation of chord-oriented texture. Scholars have proposed that the molded multi-layer veneers are cut in a plane that is not equal to any datum to obtain a mountain shape or other texture. This method has been well used in production. Xu Zhongliang proposed that the small piece of natural thin wood is processed into a regular shape, and the mosaic is formed by approximating symmetry, segmentation, contrast, uniform distribution, etc., and the pattern formed is relatively regular, and the processing technique of the irregular pattern is very complicated. . In addition, Tang Kaijun et al. proposed to distribute the thickness of the veneer according to a certain rule in the formation of the veneer to produce a thin wood radial pattern, and use the concave and convex mold to produce a chord pattern when compressing the multi-layer veneer. Wan Mingmin et al. established a curved surface model formed by layers of various layers of a multi-layer veneer under certain conditions; the model takes into account factors such as mold radius, height, spacing between two molds, pressure, etc. Reliability, consistent with the actual situation, easy to use. Huang Yongnan and Cai Zhiming studied the application of computer technology in the design and manufacture of wood molds, and explained the application process with examples. The organic combination of computer technology and texture simulation is an important direction for the future development of artificial wood, which will greatly improve the scientific and technological content of artificial wood, and can greatly improve product quality, shorten production cycle, and reduce unnecessary resources and funds. waste.
2.3 Thin slice and veneer technology for artificial thin wood
With the growing prosperity of the building decoration industry, the veneer veneer technology has been more widely used, but at present, there are fewer and fewer precious tree species that can be mined in China. In order to further save precious tree species and improve the utilization rate of artificial wood products, Developed towards meager wood. The thickness of the thin wood is mostly controlled at 0.07-0.20mm, while the thickness of the thin wood of the existing planer can only reach 0.15mm, which cannot fully meet the requirements of use. The new thin-plate planer developed by Shandong Gongyou Group and Weihai Wood Machinery Group has solved this problem well. This new type of planer has been designed to improve the design of the left and right base slides, feed devices, frames and clamping beams, and gas control systems. In addition, in the development of the QB295 thin-plate planer, the single-chip PPIC6C57 is used as the CPU, and the hybrid stepping motor is the driving component of the feed system. The two together constitute a high-precision automatic feed system controlled by the microcomputer. Greatly improved the cutting precision of wood.
The traditional method of wood-based veneer veneering is to use dry paste, that is, the thin wood is first dried to a certain moisture content and then the adhesive is applied (the moisture content of the dry thin wood is generally 8% to 12%). The dried thin wood adsorbs some glue, and the penetration is not very serious, but the thin wood is easy to crack and warp during storage and transportation, and the breakage rate is high, and it is not easy to operate when pasting. The so-called wet paste is that the wet wood is not dried (generally the moisture content reaches 30% to 80%), and is directly adhered to the artificial board substrate at a high moisture content. Due to the high moisture content of the thin wood, the board surface is flat, not easy to be broken, and the operation is convenient. The thin wood wet sticking process can save a lot of thin wood, reduce the production cost of the thin wood, and reduce the process of the adhesive sticking process. However, the wet-sticking process is more difficult to control the penetration. When Li Kongqin and other UF/PVAC two-ply mixing weight ratio is 80/20, the penetration rate of the veneer veneer is zero, and the immersion peeling test is qualified.
3. Development trend of artificial wood
The production of artificial wood involves the bleaching and dyeing of veneers, the gluing of veneers, the simulation of texture, the cutting of thin wood, etc., involving dye chemistry, adhesive science, computer technology, woodworking machinery and other multidisciplinary, A wide range of knowledge, although the current research has achieved remarkable results in all aspects, but in the uniformity of veneer dyeing, improvement of computer color matching technology suitable for wood dyeing, computer simulation of texture, and thin wood cutting The strength and transparency of the thin wood, as well as the special adhesive for artificial thin wood, have yet to be further studied.
(1) Due to the different veneer species of artificial wood, the composition varies greatly, and the permeability to dyes is also very different, and dye uniformity is an important aspect to ensure product quality. Therefore, in terms of dye uniformity, Further research is needed. The computer color matching process is a mechanized process. The system does not consider any influencing factors and only relies on database work. The actual dyeing is a complex physical and chemical change process. The various process conditions (temperature, pressure, time, bath ratio, etc.) during dyeing. ), has a crucial impact on the results of dyeing. Therefore, in order to ensure the accuracy of the computer color matching, in the actual application, the formula given to the color matching system must be analyzed, and the sample is verified in the laboratory according to the formula, and finally the actual formula is found to find the database formula and the actual formula. The regularity changes between the parameters, the database is constantly revised and improved, so that it is further consistent with the actual application.
(2) Whether the quality of the texture simulation directly affects the quality of the artificial wood, especially for the production of the string-oriented texture, is even more important. Although the current research on string-to-texture has achieved certain results, it is still immature in the combination of computer technology and texture simulation. Therefore, how to apply texture recognition technology and computer-aided design technology to texture simulation Among them, it has become an important research topic.
(3) Although the timber resources for producing artificial thin wood are relatively abundant, for China, the task of protecting wood resources is still arduous. Therefore, in order to save valuable veneer materials and improve economic efficiency, artificial thin wood will become thinner and thinner. Therefore, thinner wood should be thinner with a more sophisticated and more automated planer. The development of a thin wood thin cutting machine will be a key point. In addition, the study of the strength of the micro-thin wood and the study of the penetration condition is also an important aspect.
(4) The current adhesive varieties are mostly unable to meet the requirements for the manufacture of artificial thin wood. Therefore, the development of artificial wood special adhesives with low cost, good wet viscosity, good water resistance, no pollution on the surface paint and suitable for wet-coating process will be developed. It is an important topic for future research institutions and corporate R&D departments.
In short, large-scale mass production of artificial wood is an important means to protect precious tree species and alleviate the contradiction between supply and demand. It is necessary to study related technologies. Although some achievements have been made, further research is needed. the study.
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