In recent years, solid wood furniture has been popular in the market. The characteristic of solid wood furniture is its beautiful curve. Do you know the origin of solid wood bending? How can we do the solid wood bending process? Let's take a look at it together.
First, the origin of solid wood bending
At the beginning of the 19th century, Qumu furniture technology was introduced to Japan from Germany. After the 1880s, China began to pay more and more attention to this process. As early as 30 years ago, Shanghai Woodware Factory pioneered the solid wood bending process in China. After the trial production of solid wood curved furniture products was successfully put into the market, it was widely welcomed. Nowadays, many new Chinese-style furniture on the market are made of solid wood bending technology, which is graceful and simple.
Second, the principle of solid wood bending
When the wood is bent, the concave layer is formed by the neutral layer as the boundary, and the tensile stress is generated on the convex surface, so that the convex wood has different degrees of elongation; the concave surface generates compressive stress, so that the concave wood has different degrees of compression, and the stress distribution is The surface gradually decreases toward the middle, and the middle layer of fibers (neutral layer) is neither stretched nor compressed. When the tensile and compressive stresses experienced exceed the tensile strength limit or compressive strength limit of the material, the wood is destroyed.
When the wood is bent, it is necessary to study and understand the deformation law of the tensile and compressive stress of the wood.
The compression deformation of the grain is related to the tree species, and the compression deformation of the soft leaves of soft needles and soft broad leaves is 1%-2%, and that of hard broadleaf air is 2%-3%. This is because the hardwood leaves have a wide and thick wood ray structure between the layers of the hardwood, which makes the connection firm, so it is not easy to lose stability and damage during deformation.
Softening treatment can increase the grain compression and tensile deformation of the wood. The softening treatment can slightly increase the anti-stretch deformation of the grain, generally from 1% to 2%. However, the compression deformation of the grain is much more than that of the air dry material. After softening treatment, the compression deformation of hard hardwood leaves can reach 25%-30%, and the compression deformation of softwood leaves is 5%-7%.
Different tree species are allowed to have different deformation and compression deformation, and thus their bending properties vary greatly.
Third, the solid wood bending process
1. Choosing wool and processing
The moisture content of the wool which is directly bent without being softened is controlled to be 10%-15%; the moisture content of the square material to be softened and treated should be 25%-30%; the moisture content of the high frequency softening treated wool should be greater than 20 %, and the treated wool has a moisture content of 10% to 12%. The wood is machined to the desired shape.
2, softening treatment
The most suitable method for industrialized mass production in the softening treatment is the high-temperature steam method. In the factory, the long wooden strips are placed in the equipment, and then the furnace door is closed, and the switch is pressed, and a large amount of steam is generated immediately and there is a unique wood. The fragrance is coming out.
3, bending molding
Bending is the most important and complicated part of the whole process. There are different methods depending on the thickness and bending radius of the bending part and the bending dimension.
After a fixed period of time, the furnace door is opened to remove the wood, the wood is caught in a curved mold, and the wood is pressed along the edge of the mold by means of a pressing tool, and the wooden strip forms the same arc shape as the mold.
4, low temperature drying - natural cooling - stereotype
Dry setting is the requirement to make the moisture content stable to lignin. Because the moisture content of the wood after steam is large, it is not good to carry out the next step. It can only be cooled and air-dried in a cool and dry place, and the water content should be reduced to below 10%, otherwise the abandonment rate will increase.
5, bending parts processing
After bending, the machined surface or machining reference of the bent part is inaccurate. To achieve high quality requirements, it must be reworked to re-determine the reference and profile machining.
After the bending member is finished, the bending quality can be determined according to whether the component is discolored, broken, or rebounded. In order to achieve excellent curved wood quality, there is no mistake in every step above. Wood as a natural product is not exactly the same, so grasp the details to determine success or failure!
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