JP6663659B2 - Size setting method of through hole of perforated sound absorbing board that constitutes sound absorbing structure - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for setting dimensions of through holes of a perforated sound absorbing board constituting a sound absorbing structure in a sound absorbing structure provided with a perforated sound absorbing board installed on an inner wall surface of a building.

  2. Description of the Related Art Perforated sound-absorbing boards having a large number of holes have been used as interior finishing materials for buildings in order to absorb indoor noise and reduce acoustic reflection on inner wall surfaces.

  In conventional perforated sound-absorbing boards, when trying to change the resonance frequency (the frequency at which the sound absorption coefficient becomes maximum), the diameter and pitch of the holes are changed for each location, the thickness of the board is changed, Measures have been taken to change the thickness of the air layer on the back.

  In room acoustic design, interior finishing may be done using perforated sound-absorbing boards with different resonance frequencies, but in this case, the diameter and pitch of the holes differ from place to place, and there is no sense of unity in design There is a problem in that the interior is finished, and the external appearance when viewed from the indoor side is impaired.

  Turning now to the prior art, Patent Literature 1 has a structure including a substrate having a large number of small-diameter through-holes and a relatively thin surface-layer covering sheet material adhered to the surface of the substrate. A perforated sound absorbing plate is disclosed. In this perforated sound absorbing plate, a surface-side opening of a through-hole is completely closed by a sheet material, and the perforated sound absorbing plate has no holes on its surface.

  According to the sound absorbing board disclosed in Patent Document 1, although the surface properties are improved, the sound absorbing performance is not improved.

  In order to improve the sound absorption performance, if the diameter and pitch of the holes are all the same and the thickness of the board is changed or the thickness of the back air layer is changed, the size of the interior space of the room will be affected. Occurs.

  From the above, without changing the thickness of the perforated sound absorbing board and the thickness of the air layer on the back, and changing the hole diameter and pitch when viewing the perforated sound absorbing board from the front for each location. In addition, there is a strong need in the art to develop a perforated sound absorbing board whose resonance frequency is changed to improve sound absorbing performance.

JP 2001-132132 A

The present invention does not change the thickness of the perforated sound-absorbing board or the thickness of the air layer on the back surface, and does not change the hole diameter or pitch when viewing the perforated sound-absorbing board from the front for each location. It is another object of the present invention to provide a method for setting the size of a through-hole of a perforated sound absorbing board constituting a sound absorbing structure in a sound absorbing structure provided with a perforated sound absorbing board whose sound absorbing performance is improved by changing its resonance frequency.

  To achieve the above object, a perforated sound absorbing board according to the present invention is a perforated sound absorbing board provided with a plurality of through holes, wherein the through holes have a multi-stage shape in which a cross-sectional area changes in the middle thereof. It is.

  The perforated sound-absorbing board of the present invention can change the resonance frequency as desired, because the through-hole has a multi-stage shape in which the cross-sectional area changes in the middle. That is, by using the perforated sound-absorbing board of the present invention, without changing the thickness of the perforated sound-absorbing board and the thickness of the air layer on the back surface, and the diameter of the hole when the perforated sound-absorbing board is viewed from the front. It is possible to change the resonance frequency without changing the pitch or pitch from place to place. Therefore, since the diameter and pitch of the holes are the same, it is possible to form an interior finish having a sense of unity in design and excellent appearance and design.

  Here, “multi-stepped” means that two or three holes having different cross-sectional areas are sequentially continuous. The cross-sectional shape of the two or more holes forming the through-hole may be circular or polygonal such as elliptical or square.

  For example, when a multi-stage through-hole is formed from two holes having different cross-sectional areas, a hole having a small cross-sectional area or a hole having a large cross-sectional area is on the indoor side, and a hole having a large cross-sectional area or a hole having a small cross-sectional area is formed. The perforated sound-absorbing board is disposed so as to be on the air layer side on the back of the board.

  Further, a ventilation resistance material may be interposed in the through hole or on the surface of the through hole.

  This ventilation resistance member is a member that gives resistance to the vibrating air mass and converts it into heat energy. Since the through holes of the perforated sound absorbing board are provided with the ventilation resistance material, the sound absorbing characteristics can be adjusted.

  That is, the gas flow resistance is given to the through-holes by disposing the ventilation resistance material in the through-holes, and even if each through-hole is a perforated board having a relatively small size, the frequency band in which sound is absorbed is expanded. And the sound absorption coefficient can be adjusted.

  Examples of the ventilation resistance material having the sound absorbing performance include coarse wool felt made of glass wool, wool, and the like, synthetic fiber materials such as acetate and nylon, urethane materials, and open-cell porous materials.

In addition, the perforated sound-absorbing board is arranged such that a portion having a large cross-sectional area or a portion having a small cross-sectional area faces the air layer on the back surface of the board. each L _1, a ₁ length of a small portion and the cross-sectional area and a diameter of, and phi _1, a large part of the cross-sectional area length and cross-sectional area and volume of the L _2, a _2, V ₂ respectively, through holes one the volume per air layer (value obtained by multiplying the thickness of the air layer to the square of the pitch of the through holes) upon a V _3, perforated sound absorption board resonance frequency: f ₀ is the acoustic velocity: using c ₀ It can be set by the following equation.

  By setting the above various physical values, a perforated sound absorbing board having a desired resonance frequency can be designed. In the case where the cross-sectional shape of the through hole is a polygon, “diameter” in the above equation is to be read as “maximum length (for example, maximum diagonal line) in the cross section”. The validity of the above formula has been verified by the present inventors.

  Other embodiments of the perforated sound-absorbing board of the present invention include the following two embodiments.

  One form is two perforated sound-absorbing boards in which the cross-sectional areas of the respective through-holes are different, and the two perforated sound-absorbing boards face each other such that the corresponding through-holes communicate with each other. The two are connected in a state of being in contact with each other, and a multi-stage through-hole whose cross-sectional area changes in the middle thereof is formed.

  In this embodiment, a perforated sound-absorbing board may be formed from two boards of different materials.

  In another embodiment, holes having different cross-sectional areas are formed from both side surfaces of one effective sound absorbing board, and multi-stage through holes are formed in which the respective holes communicate and the cross-sectional area changes on the way. Is what it is.

  Furthermore, the present invention extends to a sound absorbing structure. The sound absorbing structure includes the perforated sound absorbing board, an air layer on the back surface of the perforated sound absorbing board, and a ventilation resistance provided in the air layer. And materials.

  In this sound absorbing structure, a ventilation resistance material is provided in the air layer on the back surface of the perforated sound absorption board, and the above-described glass wool or the like can be applied to the ventilation resistance material. Here, the perforated sound-absorbing board may also have a ventilation resistance material inside, and the air layer on the back surface may have a ventilation resistance material.

According to the sound-absorbing structure in which the size of the through-hole is set by the method for setting the size of the through-hole of the perforated sound-absorbing board constituting the sound-absorbing structure of the present invention, the perforated sound-absorbing board constituting the sound absorbing structure has a cross-sectional area in the middle thereof. By changing the thickness of the perforated sound-absorbing board and the thickness of the air layer on the back by providing a multi-stage through-hole that changes, the perforated sound-absorbing board when viewed from the front The resonance frequency can be changed as desired without changing the diameter and pitch of the holes from place to place, and the sound absorption performance can be improved. Also, since there is no need to change the surface pore shape, the design is good.

It is a schematic diagram showing Embodiment 1 of a perforated sound absorbing board and a sound absorbing structure of the present invention. FIG. 2 is a view taken in the direction of arrow II in FIG. It is a schematic diagram showing Embodiment 2 of a perforated sound absorbing board and a sound absorbing structure of the present invention. It is a schematic diagram showing a sound absorbing structure according to a third embodiment of the present invention. (A), (b) is a schematic diagram explaining the manufacturing method of the perforated sound absorbing board. It is the figure which showed the graph based on the experimental result and the design formula which verify the validity of the design formula regarding the resonance frequency of a perforated sound absorbing board.

  Hereinafter, embodiments of a perforated sound absorbing board and a sound absorbing structure of the present invention will be described with reference to the drawings. Although the perforated sound absorbing board of the illustrated example is provided with a through-hole composed of two holes having different cross-sectional areas, it may be provided with a through-hole composed of three or more holes having different cross-sectional areas. Good. Although the cross-sectional shape of the through-hole of the perforated sound absorbing board in the illustrated example is circular, the through-hole may have a cross-sectional shape other than circular, such as an elliptical shape or a polygonal shape. Further, the sound absorbing structure of the illustrated example is a perforated sound absorbing board in which a hole having a large cross-sectional area faces the air layer, but a hole having a small cross-sectional area faces the air layer. There may be.

(Embodiment 1 of perforated sound absorbing board and sound absorbing structure)
FIG. 1 is a schematic view showing a perforated sound absorbing board and a sound absorbing structure according to a first embodiment of the present invention, and FIG. 2 is a view taken in the direction of arrow II in FIG.

  The illustrated perforated sound-absorbing board 10 has a plurality of through-holes 2 opened at equal intervals in the vertical and horizontal directions with respect to the board 1 to constitute the entire board.

  The board 1 is formed from a gypsum board or calcium asbestos silicate board having a thickness of about 10 mm to about 20 mm, a flexible board, a medium fiber board, a particle board, a wood-based plywood, a hard fiber board, or the like.

  The through-hole 2 has a multi-stage shape in which two holes having a circular cross section and different cross-sectional areas are continuous, and the cross-sectional area changes in the middle thereof. The perforated sound-absorbing board 10 is disposed so that the large hole 2 b of the perforated sound-absorbing board 10 faces the air layer G on the back surface of the perforated sound-absorbing board 10, forming a sound absorbing structure 20. On the opposite side of the perforated sound-absorbing board 10 across the air layer G, a base material W (sound insulation material, reflective material) is present, and the base material W is formed of an appropriate material that reflects sound. I have.

  Since the perforated sound-absorbing board 10 has the through-hole 2 having a multi-stage shape in which the cross-sectional area changes in the middle, the resonance frequency can be changed as desired.

Here, with reference to FIG. 2, of the through-hole 2, the small hole 2a of the cross-sectional area length and cross-sectional area and the diameter L _1, a _1, respectively, and phi _1, the length of the large hole 2b of the cross-sectional area the cross-sectional the area and volume and each _{L 2, a 2, V 2} , when the volume of the through holes one per air layer was V _3, perforated sound absorption board resonance frequency: f ₀ is the acoustic velocity: the c ₀ It can be set by the following equation used.

In FIG. 2, the volume V ₃ of the air layer is a shared volume of each through hole 2 (a rectangular area surrounded by a dotted line in the figure).

  Therefore, by setting the above various physical values, it becomes possible to design the perforated sound absorbing board 10 and the sound absorbing structure 20 having a desired resonance frequency.

  As described above, according to the perforated sound absorbing board 10 and the sound absorbing structure 20 shown in the drawing, the board 1 is provided with the through-hole 2 having a multi-stage shape whose cross-sectional area changes in the middle thereof. Without changing the thickness of the perforated sound absorbing board 10 or the diameter and pitch of the through holes 2 when the perforated sound absorbing board 10 is viewed from the front, without changing the thickness of the perforated sound absorbing board 10 from the front. Can be changed as desired. Therefore, it is possible to exhibit sound absorption for various sounds without changing the shape of the hole appearing on the surface, and since the diameter and pitch of the through holes 2 are the same, a sense of unity in design is obtained. Yes, it can form an interior finish with excellent appearance and design.

(Embodiment 2 of perforated sound absorbing board and sound absorbing structure)
FIG. 3 is a schematic diagram showing a perforated sound absorbing board and a sound absorbing structure according to a second embodiment of the present invention.

  The perforated sound-absorbing board 10A constituting the illustrated sound-absorbing structure 20A has a through-hole 2 and a ventilation resistance material 3 interposed therein. The ventilation resistance material 3 is made of a sound-absorbing material having air permeability, and is made of coarse wool made of glass wool, wool, or the like, synthetic fiber-based material such as acetate or nylon, urethane-based material, open-cell porous material, or the like. it can. Note that a configuration in which the ventilation resistance material 3 is provided on the surface of the through hole 2 instead of the inside of the through hole 2 may be employed.

  Since the through-holes 2 of the perforated sound-absorbing board 10A are provided with the ventilation resistance material 3, even if each of the through-holes 2 is a perforated sound-absorbing board 10 having a relatively small size, the gas flow resistance in the through-hole 2 is reduced. It is possible to extend the frequency band provided and absorbed.

(Embodiment 3 of sound absorption structure)
FIG. 4 is a schematic diagram showing Embodiment 3 of the sound absorbing structure of the present invention.

  The illustrated sound absorbing structure 20B has a structure in which the ventilation resistance material 4 is disposed in the air layer on the back surface of the perforated sound absorption board 10A provided with the ventilation resistance material 3. Here, the ventilation resistance material 4 can also be formed of glass wool or the like, similarly to the ventilation resistance material 3, and the ventilation resistance materials 3 and 4 may be made of the same material or different materials. .

  The sound absorption performance is further improved by disposing the ventilation resistance material 4 also in the air layer on the back surface of the perforated sound absorbing board 10A.

(How to make perforated sound absorbing board)
Next, with reference to FIGS. 5A and 5B, a method of manufacturing the perforated sound absorbing board will be outlined.

  First, in the manufacturing method shown in FIG. 5A, two boards 1A and 1B having different cross-sectional areas of the through holes 2a and 2b are overlapped so that the corresponding through holes 2a and 2b are continuous. This is a method of manufacturing a perforated sound-absorbing board by bonding both boards 1A and 1B to each other.

  In this manufacturing method, boards 1A and 1B made of different materials may be used. Also, when forming a through hole composed of three holes having different cross sections, three boards having through holes having different cross sections are prepared, overlapped so that the corresponding through holes are continuous, and adhered to each other. Then, a perforated sound absorbing board may be manufactured.

  On the other hand, the manufacturing method shown in FIG. 5B is a manufacturing method in which holes are opened from the front and back surfaces of the board 1 with drills D1 and D2 having different diameters to form multi-stage through holes.

  With any of the manufacturing methods, it is possible to manufacture a perforated sound-absorbing board provided with multi-stage through-holes having a cross-sectional area that changes in the middle thereof at an equal pitch.

(Example)
The present inventors have developed a perforated sound-absorbing board of the present invention (a plurality of types in which the lengths and diameters of two holes constituting a through-hole are variously changed) and a conventional perforated hole having a through-hole having a uniform cross-sectional area. A sound-absorbing board was manufactured, and each resonance frequency was calculated. Hereinafter, Table 1 shows the specifications of the board and the hole and the measurement results of the resonance frequency.

  As shown in Table 1, the product of the present invention has exactly the same board thickness, surface hole diameter and pitch, and specifications of the air layer as the conventional product, but the length of the hole having a small cross-sectional area can be changed. It was confirmed that the resonance frequency could be changed by providing a hole having a large sectional area. In other words, it is shown that even if the design shape of the hole visible on the surface is the same and the air layer and the board thickness are the same, sound can be absorbed at a different resonance frequency (frequency at which the sound absorption coefficient becomes maximum) by using the product of the present invention. Was done.

(Experiment to verify the validity of the design equation for the resonance frequency of the perforated sound absorbing board and its results)
The present inventors conducted an experiment for verifying the validity of the design equation regarding the resonance frequency of the perforated sound absorbing board described above. Specifically, three types of test specimens were manufactured in which the length of a hole having a small cross-sectional area was changed or the length of a hole having a large cross-sectional area was changed. The resonance frequency was measured while changing the values to 8 mm, 5 mm, and 2 mm, and a graph was created based on the values calculated by the above design formula, and the correlation between the actually measured values and the graph was verified.

  Hereinafter, Table 2 shows the specifications of the test pieces, and FIG. 6 shows a graph based on the measurement results and the design formula.

  From FIG. 6, it can be seen that in all of Examples 1 to 3, the graph (calculated value) based on the design formula and the actual value have a very high correlation.

  From this verification result, the validity of the above-described design equation is proved. In addition, the experimental results show that the resonance frequency (sound absorption coefficient) can be increased without changing the pitch of the through holes, the thickness of the board, and the thickness of the air layer by merely reducing the diameter of the hole with a small cross-sectional area. It can be seen that the maximum frequency can be reduced. Furthermore, it can be seen that the smaller the ratio of the length of the hole having the small cross-sectional area to the hole having the large cross-sectional area is, the greater the change in the resonance frequency when the diameter of the hole having the small cross-sectional area is reduced.

  As described above, the embodiments of the present invention have been described in detail with reference to the drawings. However, the specific configuration is not limited to this embodiment, and there are design changes and the like without departing from the gist of the present invention. They are also included in the present invention.

  1, 1A, 1B: board, 2: through hole, 2a: hole with small cross-sectional area (through hole), 2b: hole with large cross-sectional area (through hole), 3, 4: ventilation resistance material, 10, 10A: yes Perforated sound absorbing board, 20, 20A, 20B: sound absorbing structure, G: air layer, W: base material

Claims (5)

A perforated sound-absorbing board having a plurality of through-holes, wherein the through-hole has a multi-stage shape in which the cross-sectional area changes in the middle thereof,
An air layer on the back of the perforated sound absorbing board,
A base material on the opposite side of the perforated sound absorbing board in the air layer,
Of the through holes, the perforated sound-absorbing board is installed in a state where a large cross-sectional area or a small cross-sectional area faces the air layer on the back of the board,
Of the through-holes, the length, cross-sectional area and diameter of the small cross-sectional area are L1, a1, and φ1, respectively, and the length, cross-sectional area, and volume of the large cross-sectional area are L2, a2, and V2, respectively. When the volume of the air layer per hole is V3, the resonance frequency of the perforated sound absorbing board: f0, which is the frequency at which the sound absorption coefficient becomes the maximum, is set by the following equation using the sound speed: c0.

A method for setting the size of a through hole of a perforated sound absorbing board constituting a sound absorbing structure . The method for setting a size of a through-hole of a perforated sound-absorbing board constituting a sound-absorbing structure according to claim 1, wherein a ventilation resistance material is interposed inside the through-hole or on a surface of the through-hole. Two perforated sound-absorbing boards with different through-hole cross-sectional areas,
Two perforated sound-absorbing boards are connected to each other in a state where they are in surface contact with each other so that the corresponding through-holes communicate with each other, and a multi-stage through-hole whose cross-sectional area changes in the middle thereof is formed. A method for setting the size of a through hole of a perforated sound absorbing board constituting the sound absorbing structure according to claim 1 . 3. The multi-stage through hole according to claim 1, wherein holes having different cross-sectional areas are formed from both side surfaces of one effective sound absorbing board, and the respective holes communicate with each other to change the cross-sectional area in the middle. A dimension setting method of a through hole of a perforated sound absorbing board constituting the sound absorbing structure according to the above . The method for setting the size of a through hole of a perforated sound absorbing board constituting a sound absorbing structure according to any one of claims 1 to 4, wherein a ventilation resistance material is provided in the air layer .

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