Sound absorption wood board

Abstract

A sound absorption wood board belongs to the field of building decoration materials and is characterized in that a plurality of micropores are formed in a wide surface of a longitudinal section of the wood board, the hole depth is perpendicular to the surface of the wide surface, and the micropores are conical blind holes. The micropores are communicated with a plurality of cross section holes of the wood, a criss-cross micropore network is formed in the wood, sound waves can be deeply absorbed, the sound absorption capacity of the wood board is improved, the wood board is used for indoor decoration, the characteristics that original wood is attractive in appearance and free of pollution are reserved, and the wood board is suitable for being used as a sound absorption material of an indoor wall board or a shelf board.

Description

Technical Field

[0001] The invention relates to a sound-absorbing wooden board, belonging to the field of building decoration materials. Background Art

[0002] Sound-absorbing materials used for interior wall panels or ceiling panels are indispensable building materials for places dedicated to sound effects, such as gymnasiums, concert halls, movie theaters, live broadcast rooms, recording studios, classrooms, airport waiting rooms, shopping malls, etc.

[0003] Commercial sound-absorbing materials, such as glass wool, slag wool, gypsum, foam plastic, perlite, rock wool, and foam metal, are mostly derived from mineral materials and their derivatives and are porous. Most existing sound-absorbing materials pose potential risks to human health, especially the lungs and eyes. The processing process consumes huge amounts of energy and emits CO2 and other pollutants.

[0004] Wood is also an important sound-absorbing material, but research has found significant differences in sound absorption performance between different wood surfaces. The cross-section of wood is rich in micropores perpendicular to the surface. These micropores are formed when the wood's cells are transversely cut. Sound waves entering these micropores are effectively absorbed and dissipated, resulting in an average sound absorption coefficient exceeding 0.2. In contrast, the longitudinal section of wood contains only grooves parallel to the surface and lacks micropores, resulting in an average sound absorption coefficient of only around 0.1. In practical applications, because trees are cylindrical in shape, the longitudinal section of a column has the largest usable area. Therefore, the longitudinal section of wood is the surface of raw material used. However, the longitudinal section of wood has a low sound absorption coefficient and is therefore not suitable for use as a sound-absorbing material.

[0005] Application No. 202510236684.3 discloses a plate-form composite sound-absorbing structure, specifically disclosing that the microporous plate (10) is one of the following: aluminum plate, iron plate, steel plate, copper plate, or wooden plate. The microporous plate (10) is provided with a plurality of first through holes (11), the first through holes of the microporous plate (10) having a diameter of 1.2 mm and a thickness of 1.0 mm, and is attached to the building wall of a substation for use. From the disclosed technology, it can be seen that providing through holes on a microporous plate with a thickness of 1.0 mm is equivalent to perforated wallpaper. Regardless of whether the longitudinal section or the cross section is used, it cannot be used independently as an interior wall panel or shed board. Moreover, in the field of decorative materials, no wooden board used as a sound-absorbing material has been found so far. Summary of the Invention

[0006] The purpose of the present invention is to provide a sound-absorbing wooden board, which improves the sound absorption capacity of the wooden board by changing the microstructure of the wooden board to form a criss-cross microporous interwoven network, making it a sound-absorbing material in the field of decorative materials.

[0007] The technical solution of the present invention is: a sound-absorbing wooden board, on a wide surface of the longitudinal section of the wooden board, a plurality of micro holes with a diameter range of 50-300 μm are made, and the hole depth is perpendicular to the surface of the wide surface.

[0008] Furthermore, the microholes are blind holes.

[0009] Furthermore, the thickness of the wooden board is 3-30 mm, and the depth of the micropores ranges from 2 mm to 80% of the thickness of the wooden board.

[0010] Furthermore, the micropores are tapered holes, and the diameter of the holes on the surface of the wooden board is larger than the diameter of the holes extending into the interior of the wooden board.

[0011] Furthermore, the density of the micropores is 10-100 per cm 2 .

[0012] The beneficial effects of the present invention are:

[0013] 1. The sound absorption coefficient is significantly improved: the depth direction of the manufactured micropores is perpendicular to the surface where the micropores are located, which is conducive to the unimpeded entry of sound waves into the wood board; the micropores are designed as tapered holes, which can make the contact area between the micropores and the sound waves on the surface of the wood board larger, which is conducive to the maximum absorption of sound waves; the manufactured micropores have a certain depth, which increases the chance of connecting with multiple cross-sectional holes of the wood itself, forming a criss-cross micropore network inside the wood, and increasing the porosity of the wood; the manufactured micropores are designed as blind holes, which prevent sound waves from overflowing at the micropore terminals The sound waves reflected at the blind end of the micropores can automatically turn and enter the micropore network through the cross-sectional holes connected to them. The blind holes play an important guiding role; the sound waves entering the micropore network rub and collide with the rough tissue surface of the micropores and holes, are rapidly attenuated, and the sound energy is converted into heat energy. Therefore, the vertical and horizontal combined micropore network structure deeply absorbs the sound waves, which makes the sound absorption capacity of the wooden board produce a qualitative breakthrough. From the sound absorption performance test of the wooden board, it can be seen that the rate of increase in the sound absorption coefficient is between 47.74% and 83.19%.

[0014] 2. Because the micropores created in the present invention are tiny, they do not block the grain direction of the wood surface, allowing the original grain, color, and pattern of the wood surface to remain clearly visible, thereby maintaining the aesthetic characteristics of the original wood and maintaining the beautiful and pleasant effect of the decorative material. In addition, because the present invention designs the minimum pore diameter of the micropores to be 50μm, it adapts to the processing capabilities of ordinary punching machines and can keep the punching cost at a minimum level. The maximum pore diameter is designed to be 300μm, which is comparable to the maximum size of the micropores in the cross-section of wood of most tree species. For example, the cross-section of hardwood wood has a size range of 25-400μm, of which the number of micropores with a diameter greater than 300μm is less than 3%. Therefore, the sound absorption coefficient of the present invention is comparable to that of the cross-section of wood, but the combination of vertical and horizontal micropores has produced a qualitative breakthrough in its sound absorption capacity, with the average rate of increase in the sound absorption coefficient reaching 63.23%.

[0015] 3. Meet the mechanical strength requirements: As a decorative material with sound-absorbing function, wooden boards need to have corresponding mechanical strength, including bending strength, bending elastic modulus and compressive strength (cross grain). Of course, the thicker the wooden board, the higher the mechanical strength of the wood. The present invention selects a wooden board thickness of 3-30mm as a sound-absorbing wooden board, because when the thickness is less than 3mm, the values ​​of these mechanical indicators of the wooden board will drop significantly, and it is no longer suitable for use as a wallboard (decorative board); when the thickness is higher than 30mm, the cost increases. Experiments have shown that the thickness of the wooden board designed by the present invention not only meets the mechanical strength requirements of the product for use as an interior decoration material, but also saves costs and reduces waste, and its economy and practicality achieve the best effect. Mechanical strength is closely related to the depth of micropores. As the depth of micropores increases, the sound absorption effect of wood is better, but the mechanical properties of wood gradually decrease. The present invention designs the micropore depth to be 2mm to 80% of the thickness of the wooden board. Experiments have shown that when the micropore depth does not exceed 80% of the thickness of the wooden board, the mechanical strength does not affect the performance of the interior decoration material, and the sound absorption effect achieved is the best. As the density of micropores increases, the rate of improvement of the sound absorption coefficient will increase, but the transverse compressive strength will further decrease. In short, the thickness, diameter, depth and density of the micropores of the wood board are interdependent with the sound absorption effect and mechanical strength. While pursuing the sound absorption effect, the present invention takes into account the influence of various parameters on the mechanical strength of wood, and reasonably designs the value range, which can make the wood board a widely used sound-absorbing material.

[0016] 4. Wide range of applications: The present invention chooses to make holes on the wide surface, which is the commonly used surface and the surface with the largest area among the wood cut surfaces. The thickness of the wood board is also a specification widely used in the field of interior decoration. Therefore, the sound-absorbing wood board of the present invention is suitable for various sound effect places.

[0017] 5. Environmental protection: Compared with sound-absorbing materials derived from mineral materials and their derivatives, sound-absorbing wood boards have superior environmental performance and are more popular and respected for their pollution-free use in interior decoration. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a schematic diagram of the present invention in which micro holes are made on a wide surface of the longitudinal section of the wooden board.

[0019] Figure 2 yes Figure 1 Enlarged view of part A in the middle.

[0020] Figure 3 It is a structural diagram of the longitudinal and cross sections of existing wood.

[0021] Figure 4 This is a schematic diagram of the microscopic organizational structure of existing wood.

[0022] In the figure: 1 trunk, 2 cross section, 3 longitudinal section, 4 width of longitudinal section, 5 narrow side of longitudinal section, 6 thickness of longitudinal section, 7 micropores, 8 pore depth, 9 hole. DETAILED DESCRIPTION

[0023] The present invention is a sound-absorbing material for indoor wall panels or shed panels. The wooden panels referred to below may be surface-treated, such as painted in the prior art, and are described in detail below with reference to the accompanying drawings.

[0024] Example 1:

[0025] Selected wood species: Populus ussuriensis Kom.

[0026] Timber size: 200mm (length) × 100mm (width) × 20mm (thickness), such as Figure 1 、 2 As shown in Figure 3, among the four longitudinal sections, select the wide surface 4 of the longitudinal section and use the laser machine to make uniformly distributed micropores in sequence with a density of 10 / cm 2 The micropores were 150 μm in diameter and 15 mm deep. They were conical blind holes, with the aperture on the wood surface being the larger end of the cone, and the micropore depth perpendicular to the surface. The laser machine had a lens height of 5.5 mm, a feed speed of 215 mm / s, and a light intensity of 38%. The resulting sound absorption coefficient was 0.1737.

[0027] Example 2: Selection of Timber Species: Populus ussuriensis Kom.

[0028] Timber size: 200mm (length) × 100mm (width) × 20mm (thickness), such as Figure 1 、 2 As shown in Figure 3, among the four longitudinal sections, select the wide surface of the longitudinal section and use the laser machine to make micropores in sequence with a density of 50 / cm 2The microholes were 300 μm in diameter and 15 mm deep. They were conical blind holes, with the aperture on the wood surface being the larger end of the cone, and the microhole depth perpendicular to the surface. The laser machine had a lens height of 7.0 mm, a feed speed of 155 mm / s, and a light intensity of 50%. The resulting sound absorption coefficient was 0.1742.

[0029] Example 3: The sound-absorbing wood board of the present invention is a longitudinal section of a wood board with a thickness of 30 mm. Among the four longitudinal sections, a wide surface 4 of the longitudinal section is selected and micro-holes 7 are sequentially manufactured on the surface of the wood board using a CMA1390 CO2 laser machine. The diameter of the micro-holes is 300 μm and the hole depth 8 is 24 mm. The micro-holes are conical blind holes. The hole diameter on the wood board surface is the large end of the conical hole. The depth direction of the micro-holes is perpendicular to the surface of the wood board. The density is 10 / cm 2 The laser machine lens height was 5 mm, the feed speed was 100 mm / s, and the light intensity was 60%. The sound absorption coefficient value obtained was 0.192.

[0030] Example 4: Select a 3mm thick longitudinal section of wood. Among the four longitudinal sections, select one of the widest surfaces and use a CMA1390 CO2 laser machine to create uniformly distributed micropores 7 at a density of 100 per cm. 2 The micropores are 50 μm in diameter and 2 mm deep. They are conical blind holes, with the diameter of the hole on the wood surface being the larger end of the conical hole, and the depth of the micropores perpendicular to the surface. The laser machine lens height is 6.1 mm, the feed speed is 300 mm / s, and the light intensity is 20%. The resulting sound absorption coefficient is 0.229.

[0031] The following is a test of sound-absorbing wood panels

[0032] Test wood species: Populus ussuriensis Kom.

[0033] The dimensions of the wooden board are: 200mm (length) × 100mm (width) × 20mm (thickness), where the length is the longitudinal direction of the wood and the width is the tangential section of the wood.

[0034] Hole-making equipment: CMA1390 CO2 laser cutting machine, laser generator power is 130W, working current I max =50mA, total power P w =1.25kW, maximum feed speed is 800mm / s.

[0035] Test equipment and parameters: Beijing Shengwang Company, SW422 series impedance tube, MC3242 / 510121 four-channel data acquisition, PA50 power amplifier.

[0036] Sound wave frequency range: 500-5000Hz

[0037] Test index name: Normal sound absorption coefficient

[0038] This study uses the orthogonal test method. By analyzing the experimental results, it is determined that the factors affecting the sound absorption capacity of wood panels are three parameters: micropore diameter, micropore depth, and micropore density distribution. Each factor is set at three levels, as follows:

[0039] Micropore diameter (μm): 50, 150, 300

[0040] Micropore depth (mm): 2, 10, 15

[0041] Density distribution (pieces / cm 2 ): 10, 50, 100

[0042] According to the determined factors and levels, L9(3 4 )Orthogonal test table, see Table 1.

[0043] Table 1L9(3 4 )Orthogonal test table

[0044]

[0045] Substituting the factors and level values ​​set in this study into Table 1, we obtained the orthogonal test table for this study, see Table 2.

[0046] Table 2 Orthogonal test table of this study

[0047]

[0048] According to the nine test schemes in Table 2, a laser machine was used to make holes in the wooden boards to obtain nine treated wooden boards. The impedance tube method was used to test the sound absorption capacity of the holed wooden boards and the non-holed wooden boards (control samples). The results are shown in Table 3.

[0049] Table 3 Sound absorption performance and improvement rate of wooden boards in different test schemes

[0050]

[0051] As shown in Table 3, compared with the control sample, the sound absorption coefficient of all laser-perforated wood boards has been improved, indicating that the sound absorption capacity of the perforated wood boards is better than that of the control sample. The improvement rate of the sound absorption coefficient ranges from 47.74% to 83.19%, with an average of 63.23%. Among the three factors, the micropore density distribution has the greatest impact on the improvement of the sound absorption coefficient. The sound absorption coefficient increases significantly with the increase of micropore density. At the same time, within the set micropore diameter range, the sound absorption coefficient tends to increase with the increase of micropore diameter.

[0052] Effects of laser pore creation on wood properties

[0053] (1) Impact on physical properties

[0054] The main physical properties of wood, such as air-dry density, shrinkage rate and water absorption rate, were tested on the wood samples with nine laser pore-making schemes. The results are shown in Table 4.

[0055] Table 4 Effects of laser pore formation on the main physical properties of wood

[0056]

[0057]

[0058] Compared with the control samples, the air-dry density of the laser-pored samples decreased, which is in line with the scientific law that the material voids increase and the density decreases. The reduction ratio ranges from 6.77% to 12.41%; the shrinkage rate of the pored samples is generally higher than that of the control samples, and the increase ratio is between 3.06% and 21.43%; the water absorption rate of the pored samples increases slightly, and the increase ranges from 1.85% to 7.62%.

[0059] (2) Impact on mechanical properties

[0060] The main mechanical properties of wood, including flexural strength, flexural elastic modulus and transverse compressive strength, were tested for the nine schemes of perforated wood. The results are shown in Table 5.

[0061] Table 5 Effects of laser pore formation on the main mechanical properties of wood

[0062]

[0063] Compared with the control sample, the three mechanical strength values ​​of laser-perforated wood were reduced, with the bending strength decreasing by 0.56%-6.47%, the bending elastic modulus decreasing by 0.31%-2.95%, and the transverse compressive strength (local) decreasing by 1.05%-8.41%.

[0064] As mentioned above, the physical and mechanical properties of laser-perforated wood have changed, but there is no obvious effect on the performance of wood for interior decoration.

Claims

1. A sound-absorbing wood board, characterized by: A plurality of micro holes with a diameter ranging from 50 to 300 μm are made on a wide surface of the longitudinal section of the wood board, and the hole depth is perpendicular to the surface of the wide surface.

2. The sound-absorbing wood board according to claim 1, characterized in that: The microholes are blind holes.

3. The sound-absorbing wood board according to claim 2, characterized in that: The thickness of the wooden board is 3-30 mm, and the depth of the micropores ranges from 2 mm to 80% of the thickness of the wooden board.

4. A sound-absorbing wood board according to claim 1, 2 or 3, characterized in that: The micro holes are tapered holes, and the diameter of the hole located on the surface of the wooden board is the large end of the tapered hole.

5. The sound-absorbing wood board according to claim 1, 2, or 3, characterized in that: The density distribution of the micropores is 10-100 / cm 2 .

6. The sound-absorbing wood board according to claim 4, characterized in that: The density distribution of the micropores is 10-100 / cm 2 .

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