JP4585917B2 - Sound absorbing plate and installation method thereof - Google Patents

Description

The present invention relates to setting置方method of the sound absorbing plate and its.

  In buildings close to the railway track, noise proofing may be installed because the noise from the railway track affects. In general, a railing is installed on an elevated track, but a method of reducing the influence of noise may be taken by attaching a soundproof plate to the rail.

  In this case, there are existing elevated railway tracks where heavy accessories cannot be installed due to structural strength limitations.

As a conventional sound-absorbing plate, glass wool as a typical sound-absorbing material is covered with an auxiliary plate such as a mounting frame or a punching metal for surface protection, etc. to form a plate (see, for example, Patent Document 1) And a sound absorbing plate formed by molding a ceramic or mortar material into a plate. As a ceramic sound absorbing plate, a sound absorbing plate made of a fired product of a porous ceramic plate (for example, see Patent Document 2) is known.
Japanese Patent Laid-Open No. 10-183539. Japanese Patent Laid-Open No. 7-110692.

  Glass wool as a sound-absorbing material itself is relatively light, but since the material is soft, it is necessary to cover the whole with an auxiliary plate such as the above-mentioned punching metal when constituting it into a plate body. Overall, the weight increases.

  Ceramic and mortar sound absorbing plates that can be directly attached to the base material with bolts, nuts and the like without being covered with an auxiliary plate or the like are very heavy.

  Although the sound absorbing plate described in Patent Document 2 has a high sound absorption coefficient, it is heavy and fragile, and has a disadvantage that it breaks due to freezing and expansion of moisture impregnated in the winter, and is not suitable for outdoor use.

Both of them exhibit a high sound absorption rate due to the continuous pores of a small diameter, but they are easily impregnated with moisture by the capillary principle, and the performance deteriorates due to clogging with dust, which is not suitable for outdoor use.

  Therefore, all of the above-mentioned conventional sound absorbing plates are difficult to adopt for existing railway elevated tracks where heavy accessories cannot be installed due to structural strength limitations, and are exposed to wind and rain outdoors. Maintaining performance in the environment is difficult.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to solve such a conventional problem and to provide a sound absorbing plate that is lightweight, has high sound absorbing performance, and can maintain performance in an outdoor environment.

  The sound absorbing plate is required to have excellent waterproofness and weather resistance, is not damaged by freezing, is not damaged when subjected to vibration, and is lightweight so that it can be easily installed on an existing structure.

  The sound absorption method using the sound absorption phenomenon by the air column tube is easy to design for the frequency of the noise to be absorbed, and for the noise of multiple frequencies, sound absorption is possible by installing air column tubes with different hole depths It is. However, it is necessary to provide a large number of air column tubes in order to increase the sound absorption ability, but there has been no conventional one that can be manufactured at low cost. For example, a cement panel or foam having a large number of holes has a limited number of holes, has water absorption, is weak against freezing, is brittle against vibration, and is heavy. Also, a paper or aluminum honeycomb material is expensive, and the durability of the adhesive used for manufacturing the honeycomb is low.

  Another object of the present invention is that it has excellent waterproofness and weather resistance, is not damaged by freezing, is not damaged when subjected to vibration, is lightweight so that it can be easily installed on existing structures, and is inexpensive. It is to provide a sound absorbing plate that can be manufactured.

In order to solve the above-described problems, the present invention provides a sound absorbing plate according to claim 1, which includes a sound absorbing portion in which a plurality of cylindrical holes are formed in the thickness direction of the solid body and a casing that covers at least one surface of the sound absorbing portion. The length of the cylindrical hole is two or more, the sound absorbing material is made of an organic polymer material, the bulk specific gravity of the sound absorbing part is 0.4 or less, and the inner side of the sound absorbing part is Provided is a sound absorbing plate characterized in that a sound absorbing material covered with a film having a surface density of 0.04 kg / m ² or less is provided on the surface.

The invention according to claim 2 is a sound-absorbing plate comprising a sound-absorbing portion in which a large number of cylindrical holes are formed in the thickness direction of the solid body and a casing that covers at least one surface of the sound-absorbing portion. The sound absorbing member material is made of aluminum, the bulk specific gravity of the sound absorbing part is 0.4 or less, and the surface density on the inner back side of the sound absorbing part is 0.04 kg / m ² or less. Provided is a sound absorbing plate provided with a sound absorbing material covered with a film .

A third aspect of the present invention is a sound absorbing plate comprising a sound absorbing portion in which a large number of cylindrical holes are formed in the thickness direction of the solid body and a casing that covers at least one surface of the sound absorbing portion, and the length of the cylindrical holes is reduced. It is made of resin impregnated paper or resin coated paper that has two or more types and the sound absorbing material is water resistant, the bulk specific gravity of the sound absorbing part is 0.4 or less, and the surface density on the inner back side of the sound absorbing part There is provided a sound absorbing plate provided with a sound absorbing material covered with a film of 0.04 kg / m ² or less .

  The invention of claim 4 is the invention according to any one of claims 1 to 3, wherein the thickness of the sound absorbing plate is changed continuously or stepwise so that the length of the cylindrical hole is two or more. Provide a sound absorbing plate.

  A fifth aspect of the present invention provides the sound absorbing plate according to any one of the first to fourth aspects, wherein the hole diameter of the cylindrical hole is 2 to 20 mm.

According to a sixth aspect of the present invention, there is provided a method for installing a sound absorbing plate, wherein the sound absorbing plate according to any one of the first to fifth aspects is disposed so that a side not covered with the housing faces a sound source. provide.

Further, the invention according to claim 7 is the sound absorbing plate according to any one of claims 1 to 5 , wherein the cylindrical hole is obliquely below the front of the sound absorbing plate, with the wall surface on which the sound absorbing plate is installed behind and the sound source side in front. The sound absorbing plate is installed on the installation wall so as to face the sound.

In the first aspect of the invention, since sound absorption is achieved by resonance of the cylindrical hole (one-side closed air column), the frequency band of the sound absorption target is set by adjusting the length or depth of the hole constituting the cylindrical hole. can do. Further, by making the lengths (depths) of the multiple cylindrical holes different, a plurality of frequency bands to be sound-absorbed can be set. If the lengths (depths) of the holes forming a large number of cylindrical holes are uniform, a sound absorbing effect is produced only for sound of a specific frequency. For example, when the peak of the noise level shows a flat characteristic in a wide range of 500 to 2000 Hz, the effect on the all-pass noise level is small only with a specific frequency. Rather, a sound-absorbing plate that exhibits a sound absorption coefficient in a wide range of frequencies corresponding to noise characteristics is more effective. The cross-sectional shape of the cylindrical hole may be a circle, an ellipse, a triangle, a quadrangle, or a polygon more than that. As a method of forming the cylindrical hole, mechanical drilling in a plate material, use of a honeycomb material, assembly of cylinders, a cardboard-shaped molded body (usually, a “cardboard-shaped molded body made of such an organic polymer material” In this specification, there are also methods such as laminating a plurality of ribs and laminating a plate body having a large number of ribs.

  Furthermore, it is possible to contribute to the improvement of the sound absorption effect by providing irregularities, raisings or fine pores on the surface of the cylindrical hole.

 The sound absorption part of Claim 1 has covered at least one surface with the housing | casing, and has protected the sound absorption part. In the case of covering the sound source side surface with the housing, it is preferable from the viewpoint of maintaining the sound absorption rate to use an aperture ratio of 70% or more, more preferably an aperture ratio of 85% or more. Since punching metal has an aperture ratio of about 70%, a metal mesh or the like is preferably used to increase the aperture ratio beyond that. Examples of the material of the housing include metals, organic polymer materials, and inorganic materials as long as they can be used in an outdoor environment. However, in order to reduce the weight, a thin steel plate, an aluminum plate, or an organic polymer material is preferable. A drain hole may be provided on the lower surface of the housing. The material may be changed depending on the part.

Moreover, the sound absorbing effect can be further enhanced by providing the sound absorbing material. By covering this sound absorbing material with a film having a surface density of 0.04 kg / m ² or less, the sound absorbing material can be protected from clogging with water or dust without adversely affecting the sound absorbing performance of the sound absorbing material. A more preferable range of the surface density is 0.02 kg / m ² or less, and examples of the film material include a metal foil or an organic polymer film. Since the sound absorbing material is not exposed on the surface by installing the sound absorbing material on the inner surface of the sound absorbing portion, it is possible to prevent the film from being torn. As the sound absorbing material, a fibrous material, an open cell foam or the like is preferable. If the sound absorbing part, the sound absorbing material, the film, and even the casing are made of the same material, it is easy to separate at the time of disposal and can be recycled .

 Furthermore, since the sound absorbing part of claim 1 is formed of an organic polymer material, it is excellent in water resistance and impact resistance, and its bulk specific gravity is 0.4 or less. When mounting on a viaduct or an iron bridge, the burden on the structure is small, no reinforcement is required, and the life is not shortened. The bulk specific gravity is more preferably 0.2 or less, and still more preferably 0.1 or less. The organic polymer material is not particularly limited, but considering the environment in which the sound absorbing plate is used, there is a material that is not easily damaged by impact in order to prevent damage when the sound absorbing plate hits the sound absorbing plate during construction or separately. preferable. Examples of such a material include polycarbonate, nylon, polyethylene, polypropylene, polyvinyl chloride, and polyethylene terephthalate. In order to prevent deterioration of the polymer material in outdoor use, it is preferable to use a material mixed with an ultraviolet absorber or the like. Moreover, you may provide nonflammability, a flame retardance, antibacterial property, and antifouling property according to a use.

   In the invention of claim 2, since the sound absorbing portion is made of aluminum, it is excellent in water resistance and fire resistance.

   In the invention of claim 3, since the sound absorbing portion is formed of paper having water resistance, it is water resistant and at the same time is easy to be reduced in weight.

   The invention of claim 4 is one means for changing the length of the cylindrical hole in the invention of claim 1.

   The invention of claim 5 is suitable for outdoor use because the hole diameter of the cylindrical hole is likely to be clogged with water and dust when the hole diameter is 2 mm or less, and the sound absorption effect is affected when the hole diameter is 20 mm or more. It defines the range that is easy to design.

In the invention of claim 1 , the sound absorbing part may be made of a laminate of plastic corrugated cardboard . In this case , the sound absorbing part is excellent in waterproofness and weather resistance, is not damaged by freezing, and is not damaged when subjected to vibration. Thus, it is possible to provide a sound absorbing plate that is lightweight and can be manufactured at low cost so that it can be easily installed on an existing structure. Examples of the plastic cardboard laminate include a laminate of a plurality of plastic cardboards cut into trapezoids, and a laminate of a plurality of plastic corrugated boards whose oblique sides are cut into multiple stages.

In the invention of claim 6 , the sound absorbing effect can be improved by arranging the sound absorbing plate so that the side not covered by the casing faces the sound source, and the cylindrical hole made of water or dust by the casing. Can prevent clogging.

Traditionally, it is possible to effectively carry out the sound absorption at a lower-frequency side region 500Hz has been demanded, it is difficult. For example, as shown in Example 7, only a sound absorbing portion made of plastic corrugated board and only a sound absorbing material made of glass wool cannot effectively absorb sound in a region of a frequency lower than 500 Hz, but a sound absorbing portion made of plastic corrugated cardboard. In the case where the sound absorbing material made of glass wool is provided, the noise in the low frequency region can be effectively absorbed.

In the invention of claim 7 , “front” means a sound absorbing plate installed on a vertical wall, on the opposite side of the wall, that is, in the right direction in FIG. 14. In other words, “after the wall surface on which the sound absorbing plate is installed and after the sound source side”. Compared to the case where a large number of holes are formed in a direction perpendicular to the expanding direction of the plate by installing the sound absorbing plate on the installation wall surface so that the cylindrical hole faces obliquely downward in front of the sound absorbing plate, Therefore, the length of the holes constituting the sound absorbing part can be increased, so that the sound absorbing part can be adapted to a lower frequency band without increasing the thickness, or the sound absorbing part of the same frequency band can be absorbed. On the other hand, the sound absorbing plate can be made thin. In addition, since the cylindrical hole has an obliquely downward angle, it is possible to prevent rainwater from entering. Since the sound source is located diagonally in front of the sound-absorbing plate on railway tracks and highways, the sound-absorbing effect can be greatly enhanced by installing the sound-absorbing plate on the installation wall so that the cylindrical hole faces diagonally in front of the sound-absorbing plate. .

  The sound absorption plate can be attached mechanically using bolts, screws, rivets, etc. on the wall, or a hook-shaped locking part is provided on the sound absorption plate, and a cross is also installed on the wall. There are a method of wall-mounting so as to be replaceable, and a method of adhesive bonding with an adhesive. Since it is lightweight, it does not require a large attachment method and can be easily attached.

  The sound-absorbing plate according to the present invention can be used as a sound-insulating wall in addition to a usage pattern in which the sound-absorbing plate is installed on an existing wall or structure. For example, in applications that require fire resistance, weather resistance, and scratch resistance, when installing a new sound absorbing plate as a soundproof wall after removing a new or existing soundproof wall, A plate having a relatively high surface density such as a metal plate or a flexible board may be used as the material.

  When the plate body is covered with a protective plate, the existing wall and the case may collide with each other due to vibration when the train passes and become a new sound source. In order to prevent this, there are a method of fixing the sound absorbing plate with an elastic adhesive, a method of inserting a rubber-like material between the bolts and the like.

  As described above, the present invention can provide a sound-absorbing plate that is lightweight, has high sound-absorbing performance, and can maintain the performance in an outdoor environment, and thus has the following effects.

  a. A sound-absorbing plate for reducing the influence of railway noise on the vicinity can be installed on the rail of an existing railway elevated track where heavy accessories cannot be installed due to structural strength limitations.

  b. Such a sound absorbing plate has a high penetration rate and can be manufactured using a molded body having a relatively simple shape, and has a sound absorbing frequency characteristic by combining holes with different depths or holes. It can be controlled easily and there is no variation in sound absorption characteristics between products.

  c. Since it is lightweight, it can be easily attached to a railing or the like.

  d. The cylindrical hole has a specific diameter range, the sound absorbing material is stored in the inner part of the sound absorbing part so as not to be exposed on the surface, the sound absorbing material is covered with a film, and the cylindrical hole is not horizontal but facing downward. In the outdoor environment, the sound absorption part is made of organic polymer, aluminum, and water-resistant paper. No cracking occurs. In addition, it is possible to prevent performance degradation caused by water content and dust such as a fibrous sound absorbing plate.

 e. The sound-absorbing part is made of a laminate of plastic corrugated cardboard, so it has excellent waterproofness and weather resistance, is strong against freezing, is not brittle when subjected to vibration, and is lightweight so that it can be easily installed on existing structures Therefore, it is possible to provide a sound absorbing plate that can be manufactured at low cost.

  Next, embodiments of the present invention will be described with reference to the drawings.

Example 1
1 is a front view of the sound absorbing plate, FIG. 2 is an enlarged view of a part thereof, and FIG. 3 is a cross-sectional view taken along line II in FIG.

  In these drawings, reference numeral (1) denotes a sound absorbing plate constructed according to the present invention, and is composed of a sound absorbing portion (2) and a casing (5). The sound absorbing portion (2) is formed by forming a large number of holes (4) in a plate (3) made of an organic polymer material, aluminum, water-resistant resin-impregnated paper or resin-coated paper. The housing (5) covers the upper, lower, side and back surfaces of the sound absorbing part. The bulk specific gravity of the sound absorbing part is 0.14.

  A large number of holes (4) are formed so as to be aligned vertically and horizontally, but they can be arranged in a staggered manner, randomly, or appropriately.

  Since the sound absorbing portion (2) is constituted by the plate (3) made of organic polymer material, aluminum, water-resistant resin-impregnated paper or resin-coated paper as described above, an auxiliary plate such as punching metal, etc. The shape can be maintained without covering with. Therefore, it can be installed on the base material at the place where sound is absorbed as it is by using appropriate attachment members such as bolts and nuts, and is very lightweight.

  The length of the cylindrical hole, that is, the length (depth) of the hole (4), as shown in FIG. 3, is made different by continuously changing the thickness of the sound absorbing plate. Thereby, resonance of the cylindrical hole (one side closed air column) by the hole (4) occurs, and the frequency band of the sound absorption target can be set.

 4, 5 and 6 show other forms of the sound absorbing portion of FIG. The shape of the cylindrical hole of the sound absorbing portion indicates a hexagonal shape, a circular shape, or a wave shape.

 7, 8, and 9 show other examples in which the thickness of the sound absorbing plate in FIG. 1 is changed stepwise or continuously.

Examples 2-4
In the sound absorbing plate in the form of Example 1 in which the casing is composed of an aluminum plate having a thickness of 0.5 mm, the sound absorbing plate has a width of 400 mm, a height of 700 mm, and an upper end and a lower end thickness of 140 mm and 60 mm, respectively. The material is made of polypropylene, the hole size is 5 mm square (bulk specific gravity: 0.14) (Example 2), the material of the sound absorbing part is aluminum, and the hole is 6 mm honeycomb shape (bulk specific gravity: 0.12) ) (Example 3), the material of the sound absorbing part is made of paper, and the hole is 9 mm honeycomb shape (bulk specific gravity: 0.03) (Example 4). The rate was measured. The result is shown in FIG.

Comparative Examples 1 and 2
The structure is the same as that of the second embodiment except that the thickness of the sound absorbing plate is uniform and each is formed to be 60 mm (Comparative Example 1) and 140 mm (Comparative Example 2). With respect to these sound absorbing plates (bulk specific gravity: 0.14), the sound absorption rate was measured. The result is shown in FIG.

   According to FIG. 11, the sound-absorbing plates (Comparative Examples 1 and 2) in which holes having a depth of 60 mm and 140 mm are formed in all of the plate bodies have sound-absorbing characteristics having remarkable peaks in specific frequency bands, respectively. I understand.

   On the other hand, in the sound absorbing plate (Example 2) in which holes of 60 mm to 140 mm are continuously formed in one plate body of FIG. 10, the peak of the sound absorption coefficient is higher than that of the sound absorbing plate of FIG. However, in the sound absorbing plate in FIG. 11, the sound absorption rate is greatly reduced in the frequency band outside the specific frequency band, whereas in the sound absorbing plate in FIG. The sound absorption coefficient tends to be high in a frequency band including the peripheral liquid number band of the peak of the sound absorption coefficient of the sound absorbing plate.

   Therefore, if the lengths of a large number of one-side closed tube air column portions constituting one plate body, that is, the depths of the holes are made different for each group, a plurality of frequency bands for sound absorption are set, and a wide frequency band is obtained. It can be seen that sound absorption can be performed.

Example 5
As shown in FIG. 12, in the sound absorbing plate (1) of Example 2 shown in FIG. 3, a sound absorbing material (density 32 kg / m ³ ) is provided between the sound absorbing portion (2) and the back surface portion (9) of the housing (5). A glass wool board having a thickness of 25 mm) (10) was interposed. The sound absorbing material is covered with a 10 μm thick PET film. The other points were the same as in Example 2, and the sound absorption rate was measured. The measurement results are shown in the graph of FIG.

Example 6
In FIG. 14, the sound absorbing plate is installed such that a large number of holes (4) having different lengths (depths) are inclined forward and downward in the wall (11).

Example 7
An example in which the sound absorbing portion constituting the sound absorbing plate is made of a laminate of plastic corrugated cardboard is shown in FIGS. In FIG. 15, the plastic corrugated cardboard laminate 12 is a laminate of a plurality of trapezoidal plastic corrugated boards 13 having a thickness of 5 mm and a basis weight of 800 g / m ² .

In FIG. 16, a plastic corrugated cardboard laminate (14) is a laminate of a plurality of plastic corrugated cardboard triangle pieces (15) having a thickness of 5 mm and a basis weight of 800 g / m ² cut into multi-steps. .

Example 8
In the same manner as in Example 1, a sound-absorbing plate (A) made of plastic corrugated board having a thickness of 5 mm and a weight per unit area of 800 g / m ² was produced (the hole length of the corrugated board is 50 mm, and the holes are One with an angle of 0 ° with respect to the thickness direction, one with a cardboard hole length of 100 mm, one with a hole with an angle of 15 ° with the thickness direction of the sound absorbing part, one with a cardboard hole length of 150 mm, and a hole with sound absorption With an angle of 0 ° to the thickness direction of the part). The structure of the sound absorbing plate is the same as that shown in FIG.

In the same manner as in Example 1, a sound absorbing plate (B) having a sound absorbing portion made of glass wool having a density of 32 kg / m ³ and a thickness of 25 mm was produced. The structure of the sound absorbing plate is also the same as that shown in FIG.

Further, in the same manner as in Example 5, the sound absorbing part is made of plastic corrugated board with a thickness of 5 mm and a basis weight of 800 g / m ² , and the sound absorbing material is made of glass wool board with a density of 32 kg / m ³ and a thickness of 25 mm. A sound-absorbing plate (C) was prepared (the hole length of the corrugated board is 50 mm, the hole forms an angle of 0 ° with respect to the thickness direction of the sound-absorbing part, the hole length of the corrugated board is 100 mm, and the hole is the thickness of the sound-absorbing part. The cardboard has a hole length of 150 mm and the hole forms an angle of 0 ° with respect to the thickness direction of the sound absorbing part). The structure of the sound absorbing plate is the same as that shown in FIG.

 About these sound-absorbing plates, the sound-absorption rate was measured in the range of frequency 100-5000hz. The results are shown in the graphs of FIGS.

   As can be seen from these graphs, the sound absorbing part is made of plastic cardboard compared to the sound absorbing board (A) whose sound absorbing part is made of plastic cardboard and the sound absorbing board (B) whose sound absorbing part is made of glass wool. The sound absorbing plate (C), in which the sound absorbing material is made of glass wool board, exhibits a high sound absorption coefficient on the low frequency side, particularly in the region of 500 Hz or less.

Example 9
As shown in FIG. 20, in the sound absorbing plate having the configuration of Example 5, the casing (5) is formed of an aluminum plate having a thickness of 0.5 mm, the sound absorbing portion (2) is 5 mm in thickness, and the basis weight is 800 g / It is composed of a laminate of a plurality of m ² trapezoidal plastic corrugated cardboards (13), and a sound absorbing material (density 32 kg / m ³ between the sound absorbing part (2) and the back part (9) of the housing (5)). A glass wool board having a thickness of 25 mm) (10) was interposed. The sound absorbing material is covered with a 10 μm thick PET film. The length of the cylindrical hole of the sound absorbing portion (2), that is, the length (depth) of the hole (4) is made different by continuously changing the thickness of each sound absorbing plate.

 About this sound-absorbing plate (1), the sound-absorbing rate was measured in the frequency range of 100 to 5000 hz. For comparison, only the case (5), the case (5) with a glass wool board sound-absorbing material (10), and the case (5) consisting of a stack of trapezoidal plastic corrugated cardboard (13) Parts with the part (2) were prepared, and the sound absorption coefficient was measured for these as well. The result is shown in the graph of FIG.

 As can be seen from this graph, only the housing (5), the housing (5) with a glass wool board sound absorbing material (10), and the housing (5) consisting of a stack of trapezoidal plastic corrugated cardboard (13) The sound absorbing part is made of plastic corrugated board and the length (depth) of the hole (4) is different from that of the part (2), and the sound absorbing part (2) and the rear part of the housing (5) ( The sound absorbing plate in which the glass wool board sound absorbing material (10) is interposed between 9) exhibits a high sound absorption rate on the low frequency side, particularly in the region of 500 Hz or less.

1 is a front view showing Example 1. FIG. It is a one part enlarged view of FIG. It is sectional drawing which follows the III-III line | wire in FIG. It is a front view which shows another form of the sound absorption part of FIG. It is a front view which shows another form of the sound absorption part of FIG. It is a front view which shows another form of the sound absorption part of FIG. It is a perspective view which shows another form which changed the thickness of the sound-absorbing board of FIG. 1 in steps. It is a perspective view which shows another form which changed the thickness of the sound-absorbing board of FIG. 1 continuously. It is a perspective view which shows another form which changed the thickness of the sound-absorbing board of FIG. 1 continuously. It is a graph which shows the relationship between the frequency by Examples 2-4, and a sound absorption coefficient. It is a graph which shows the relationship between the frequency by the comparative examples 1 and 2, and a sound absorption coefficient. FIG. 10 is a cross-sectional view of a main part showing Example 5. It is a graph which shows the relationship between the frequency by Example 5, and a sound absorption coefficient. It is sectional drawing in the state attached to the wall which shows Example 6. FIG. 10 is an exploded perspective view showing a plastic cardboard laminate according to Embodiment 7. FIG. 10 is an exploded perspective view showing a plastic cardboard laminate according to Embodiment 7. FIG. It is a graph which shows the relationship between the frequency by Example 8, and a sound absorption coefficient. It is a graph which shows the relationship between the frequency by Examples 2-4, and a sound absorption coefficient. It is a graph which shows the relationship between the frequency by Examples 2-4, and a sound absorption coefficient. 10 is an exploded perspective view showing a sound absorbing plate of Example 9. FIG. It is a graph which shows the relationship between the frequency by Example 9, and a sound absorption coefficient.

1 Sound absorbing plate 2 Sound absorbing portion 3 Plate body 4 Hole (closed air column)
DESCRIPTION OF SYMBOLS 5 Case 9 Back side case 10 Sound-absorbing material 11 Wall 12, 14 Laminated body of plastic corrugated cardboard

Claims (7)

A sound absorbing plate having a plurality of cylindrical holes formed in the thickness direction of the solid body and a housing that covers at least one surface of the sound absorbing part, wherein the length of the cylindrical holes is two or more, and the sound absorbing part The material is formed of an organic polymer material, the bulk specific gravity of the sound absorbing part is 0.4 or less, and the inner back surface of the sound absorbing part is covered with a film having an area density of 0.04 kg / m ² or less. A sound absorbing plate provided with a sound absorbing material . A sound absorbing plate having a plurality of cylindrical holes formed in the thickness direction of the solid body and a housing that covers at least one surface of the sound absorbing part, wherein the length of the cylindrical holes is two or more, and the sound absorbing part A sound absorbing material made of aluminum and having a bulk specific gravity of the sound absorbing portion of 0.4 or less and a surface of the sound absorbing portion covered with a film having an area density of 0.04 kg / m ² or less. sound absorbing plate, characterized in that provided. A sound absorbing plate having a plurality of cylindrical holes formed in the thickness direction of the solid body and a housing that covers at least one surface of the sound absorbing part, wherein the length of the cylindrical holes is two or more, and the sound absorbing part The material is formed of water-impregnated resin-impregnated paper or resin-coated paper, the bulk specific gravity of the sound absorbing part is 0.4 or less, and the surface density is 0.04 kg / m ² or less on the inner back side of the sound absorbing part. A sound absorbing plate provided with a sound absorbing material covered with a film . The sound absorbing plate according to any one of claims 1 to 3, wherein the length of the cylindrical hole is set to two or more by changing the thickness of the sound absorbing plate continuously or stepwise. The sound absorbing plate according to any one of claims 1 to 4, wherein a hole diameter of the cylindrical hole is 2 to 20 mm. A sound absorbing plate installation method, wherein the sound absorbing plate according to any one of claims 1 to 5 is disposed such that a side not covered by a housing faces a sound source. The sound-absorbing plate according to any one of claims 1 to 5 is installed on the installation wall so that the cylindrical hole faces the front diagonally downward of the sound-absorbing plate with the sound source side in front after the wall surface on which the sound- absorbing plate is installed. A method of installing a sound absorbing plate.

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