JP5777291B2 - Structural laminated steel sheet having sound absorption and manufacturing method thereof - Google Patents

Description

  The present invention relates to a laminated laminated steel sheet having sound absorbing properties and a method for producing the same. Specifically, the present invention relates to a structural laminated steel sheet having sound absorbing properties that absorbs a specific frequency component of sound generated from a sound source as well as being excellent in vibration damping properties.

  From the viewpoint of global environmental conservation, conversion from an internal combustion engine to an electric motor is being studied as a power source for vehicles, particularly automobiles.

  On the other hand, improvement of comfort during riding has been studied mainly for passenger cars, and in particular, attempts have been made to reduce vibration and noise during traveling.

  In order to reduce noise, it has been conventionally performed to arrange a sound absorbing material around a power source that is a main source of noise.

  In Patent Document 1, an embossed plate having a large number of through holes is attached to the inside of a vehicle body panel at a predetermined interval, and an air layer is formed between the embossed plate and the vehicle body panel. Discloses a sound absorbing panel having a porous sound absorbing material attached thereto.

  In Patent Document 2, a sound absorbing material formed by laminating a skin material and a film material on a sound absorbing material main body made of a porous material, a volume chamber formed as a concave portion by press work, and a communication with the volume chamber, A Helmholtz resonator structure consisting of a straight pipe part formed as a hole opened on the sound source side of the sound absorbing material is formed, and the ventilation of the volume chamber and the straight pipe part is covered with a porous material to block ventilation. A sound absorbing panel with a film material attached is disclosed.

  Non-Patent Document 1 discloses an acoustic filter having a Helmholtz resonator structure that absorbs frequency components of 4800 Hz and 9600 Hz of sound generated from a vacuum cleaner.

JP 2002-274287 A Japanese Patent No. 3730395

Shu Fujiwara, Efforts to make cleaner noise against noise, Denki, Japan, May 2003, pp. 33-35

  However, the sound-absorbing panel disclosed in Patent Document 1 is provided with an embossed plate having a large number of through holes at predetermined intervals and attached to the inside of the vehicle body panel, so that an air layer is formed between the embossed plate and the vehicle body panel. Since it is formed and absorbs sound, there is a problem that the boarding space is narrowed by the provision of the air layer.

  In addition, since the porous sound absorbing material is attached to the sound source side of the embossed plate, the cost of the sound absorbing material is increased in a vehicle equipped with an internal combustion engine, and in an electric vehicle equipped with an electric motor or control device that generates a specific high frequency, As a result, a large amount of sound-absorbing material having a slow frequency characteristic is used to silence a specific frequency, resulting in an increase in the weight of the vehicle.

  The sound absorbing panel disclosed in Patent Document 2 is a sound absorbing panel having a Helmholtz resonator structure. The volume chamber opening, which is peculiar to the Helmholtz resonator structure, is provided with a communication hole in a porous material. Since the film is covered inside the hole to protect the inner diameter of the communication hole, the dimension of the inner diameter of the communication hole changes due to the aging of the porous material. There was a problem that changed.

  Even if the porous material changes with time, it is effective to increase the inner diameter of the opening in order to reduce the change in the frequency component that absorbs sound. There was a problem that the thickness increased and the boarding space became narrow.

  In addition, increasing the volume chamber body increases the thickness of the porous material, that is, increases the amount of the porous material used, leading to an increase in cost.

  The sound absorption panels disclosed in Patent Document 1 and Patent Document 2 are mainly intended to absorb sound generated from an internal combustion engine. However, in an electric vehicle that is attracting attention as a next-generation vehicle, the capacity of the battery From the above problems, in order to extend the travel distance, the demand for weight reduction is more severe, and the sound absorbing member is being reviewed.

  In addition, the acoustic filter disclosed in Non-Patent Document 1 has a blade passing frequency sound of a fan that rotates with the rotation of an electric motor mounted on an electric vacuum cleaner, that is, the number of fans at a rotational speed of 600 Hz. The sound having a peak at 4800 Hz multiplied by and 9600 Hz which is its secondary component sound is absorbed.

  Therefore, the acoustic filter disclosed in Non-Patent Document 1 absorbs a frequency component different from the sound generated from the electric motor or the control device itself.

  Furthermore, the sound absorbing panels disclosed in Patent Document 1 and Patent Document 2 and the acoustic filter disclosed in Non-Patent Document 1 are mainly only sound absorbing effects, and almost no vibration damping effects can be expected.

  The sound generated from the motor and the control device is not only acoustically radiated by air propagation, but also solidly propagates to the panel that is the structure through the support portion and radiates acoustically from the panel. When used in an electric vehicle, vibration control of the panel is often a problem simultaneously with sound absorption.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a laminated steel sheet having a sound absorbing property, which has both a sound absorbing effect and a vibration damping effect, and a method for producing the same, which are arranged around a noise generation source.

  In view of the above circumstances, the present inventors investigated both the sound generated from the internal combustion engine and the sound generated from the electric motor and the motor control device.

  As a result, as shown in FIG. 6, during high speed running, the internal combustion engine generates a sound having a wide frequency band, whereas the motor and the motor control device are single or 2 It was found that there was a sound with a peak at one particular frequency.

  In addition, the sound having a peak at a single or two specific frequencies has a frequency peak in the range of 3 to 7 kHz, and the magnitude (intensity) of the peak due to changes in the running state such as vehicle speed and load. ) Changed, but the peak frequency did not change.

  Therefore, the present inventors have found that the sound absorbing panel attached around the motor and the motor control device may be a sound absorbing panel capable of absorbing a specific frequency component.

  And if it is sound absorption of a specific frequency component, without using a porous sound absorbing material that absorbs sound in a wide range of frequencies, a laminated steel plate having a laminated structure with a resin plate sandwiched between a pair of steel plates It was conceived that a Helmholtz resonator structure should be constructed, and in that case, it was found that the vibration generated from the electric motor can be absorbed simultaneously with absorbing the sound of the specific frequency component.

  The present invention has been made based on the above findings, and the gist thereof is as follows.

(1) A structural laminated steel plate used as a sound-absorbing panel to be mounted around an electric motor and an electric motor control device, and having a laminated structure in which a resin plate is sandwiched between a pair of steel plates composed of one steel plate and the other steel plate. In the damping steel plate that has
The resin plate has a plurality of through holes, and the through holes and the pair of steel plates form a plurality of volume chambers,
In one or all of the plurality of volume chambers, the one steel plate has a plurality of small through holes smaller than the plurality of through holes,
A part or all of the plurality of volume chambers communicates with the space on the opposite side of the one steel plate through the plurality of small through holes,
The laminated structure has a Helmholtz type resonator structure that absorbs a specific frequency component of 3 to 7 kHz among sounds generated from a sound source existing on the small through hole side. Laminated steel sheet.

( 2 ) A structural laminated steel plate used as a sound absorbing panel to be mounted around an electric motor and a motor control device, wherein the laminated structure has a resin plate sandwiched between a pair of steel plates composed of one steel plate and the other steel plate. In the manufacturing method of the damping steel plate having,
The resin plate is subjected to a drilling process to dispose a plurality of through holes;
The one steel plate is subjected to a drilling process, and is provided with a plurality of small through holes smaller than the plurality of through holes;
While superposing the plurality of through holes and the plurality of small through holes, the resin plate is sandwiched between the pair of steel plates, and a volume chamber is formed by the inside of the through holes and the pair of steel plates. Opening the volume chamber to the space on the opposite side of the one steel plate with the small through hole to form a laminate having a Helmholtz resonator structure;
Cutting the laminate to a predetermined length to form a laminate cut plate;
Heating said laminate switching plate, curing the resin plate, and having a step of bonding the pair of steel plate and the resin plate, having a sound absorbing property according to (1) Manufacturing method of structural laminated steel sheet.

  According to the structural laminated steel sheet having a sound absorbing property of the present invention, a large space for sound absorption is not required, and a large amount of porous sound absorbing material is not used. A structural laminated steel sheet having sound absorption can be arranged to absorb sound of a specific frequency component.

  When the structural laminated steel sheet having sound absorption characteristics of the present invention is used in a vehicle using an electric motor as a power source, for example, an electric vehicle, a large space for sound absorption is not required, so that the boarding space is not reduced. Since a large amount of porous sound-absorbing material is not attached, sound absorption can be achieved without increasing the weight of the vehicle.

  The structural laminated steel sheet having sound absorbing properties of the present invention is useful for absorbing noise having a peak in a high frequency range, which is generated from an electric motor and a motor control device.

  Furthermore, according to the method for producing a structural laminated steel sheet having sound absorbing properties of the present invention, since a large amount of porous sound absorbing material is not used, the material cost of the porous sound absorbing material is not necessary, Since the man-hour for attaching the sound absorbing material to the member is not necessary, a structural laminated steel sheet having sound absorbing properties and having vibration damping properties and sound absorbing properties by the laminated structure can be obtained at low cost.

1 shows a sound-absorbing panel that is a first embodiment of a structural laminated steel sheet having sound-absorbing properties according to the present invention, FIG. 1 (a) is a front view, and FIG. 1 (b) is an A-A line in FIG. 1 (a). FIG. It is explanatory drawing which shows a Helmholtz type resonator. FIG. 3A is a front view and FIG. 3B is a longitudinal sectional view showing a Helmholtz resonator structure in the sound absorbing panel. It is a front view of the multiple frequency sound absorption panel which is 2nd Embodiment of the structural laminated steel plate which has a sound absorptivity of this invention. FIGS. 5A and 5B are schematic longitudinal sectional views illustrating a method for producing a structural laminated steel sheet having sound absorption characteristics according to the present invention, FIG. 5A is a resin plate provided with a plurality of through holes, and FIG. 5B is Helmholtz. FIG. 5C shows a step of forming a laminated body having a resonator structure, and a step of bonding the resin plate and a pair of steel plates by heating the laminated body cut plate. It is the figure which compared the noise in the vehicle compartment at the time of high speed driving with the internal combustion engine vehicle and the motor vehicle.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. 1A and 1B show a first embodiment of a structural laminated steel sheet having sound absorption characteristics according to the present invention, FIG. 1A is a front view, and FIG. 1B is a cross section taken along A-A in FIG. FIG. Reference numeral 1 in FIG. 1 denotes a sound absorbing / damping panel.

  The sound absorbing / damping panel 1 has one steel plate 10, a resin plate 20, and the other steel plate 30, and sandwiches the resin plate 20 with a pair of steel plates 40 including the one steel plate 10 and the other steel plate 30. It has a laminated structure.

  There is no restriction | limiting in particular in the material of one steel plate 10 and the other steel plate 30, It can select suitably, The material of one steel plate 10 and the other steel plate 30 does not need to be the same.

  Any material can be used for the resin plate 20 as long as it is a thermosetting resin. The preferred material of the resin plate 20 will be described in detail in the description of the method for producing a laminated steel sheet for structural use having sound absorption characteristics of the present invention.

  The resin plate 20 has a plurality of through holes 25, and one steel plate 10 has a small through hole 15 that is smaller than the through hole 25.

  The through hole 25 is preferably a cylindrical shape as shown in FIG. 1 because of the ease of drilling into the resin plate 20, but is not particularly limited as long as it is a through hole. The same applies to the small through hole 15.

  The resin plate 20 is sandwiched between a pair of steel plates 40 including one steel plate 10 and the other steel plate 30, and a volume chamber 45 is formed by the through hole 25 and the pair of steel plates 40.

As shown in FIG. 1A, the small through holes 15 and the volume chambers 45 are arranged at equal intervals (pitch P ₁ ) with a center-to-center distance P ₁ , but they need not necessarily be arranged at equal intervals. Absent.

  The small through-hole 15 is smaller than the volume chamber 45, and the volume chamber 45 is located in the space opposite to the resin plate 20 with respect to one steel plate 10 via the small through-hole 15 (in FIG. The Helmholtz resonator structure needs to be formed in communication with the upper space of the steel plate 10.

  The center axis of the small through hole 15 and the center axis of the volume chamber 45 are preferably coincident with each other, but do not necessarily coincide with each other.

  In addition, when the small through hole 15 and the volume chamber 45 are other than a cylindrical shape, it is preferable that the respective geometric center axes coincide with each other.

  However, when the sound absorbing / damping panel 1 is used, the noise source needs to be on the small through hole 15 side. If the noise source is not present on the small through hole 15 side, the Helmholtz resonator constituted by the small through hole 15 and the volume chamber 45 does not resonate with the sound generated from the sound source, and as a result, is generated from the noise source. I can't absorb the sound.

  Here, the resonance frequency in the Helmholtz resonator will be described. FIG. 2 is an explanatory diagram showing a Helmholtz resonator. Reference numeral 50 in FIG. 2 denotes a Helmholtz resonator.

The Helmholtz resonator 50 includes a volume chamber 51 (resonance chamber) having a volume V ₀ and an opening 55 having a diameter d and a height h.

The resonance frequency f of the Helmholtz resonator 50 is obtained by the following equation (A).
f = (c / 2π) × [S / {V ₀ × (h + d / 2)}] ^1/2 (A)
Where S = (πd ² ) / 4, c: speed of sound

That is, the resonance frequency f can be arbitrarily set by changing the volume V ₀ of the volume chamber 51 and the diameter d and height h of the opening 55, and any resonance among the frequencies of the sound emitted from the sound source 56. The frequency component can be absorbed.

  The Helmholtz resonator shown in FIG. 2 is configured as follows in a laminated structure in which the resin plate 20 is sandwiched between a pair of steel plates 40 in the sound absorbing / damping panel 1 of the first embodiment.

  3 shows a Helmholtz resonator structure in the sound absorbing / damping panel 1, FIG. 3 (a) is a front view, and FIG. 3 (b) is a longitudinal sectional view.

As shown in FIG. 3, the volume chamber 51 corresponds to the volume chamber 45, and the opening 55 corresponds to the small through hole 15. When the diameter of the small through-hole 15 is d ₁ , the thickness of _one steel plate 10 is t ₁ , the thickness of the resin plate 20 is t ₂ , and the diameter of the through-hole 25 is d ₂ , the vibration damping and sound absorbing panel 1 resonance frequency f ₁ from the formula (a) can be obtained as follows.
_{f 1 = (c / 2π)} × _{[S / {V 0 × (t} 1 + d 1/2)} ] ^1/2 · · · (B)
^{_{However, S = (πd 1 2)}} / 4, V 0 = πt 2 × (d 2/2) 2, c: sound velocity

By appropriately selecting the diameter: d ₁ of the small through-hole 15 and / or the plate thickness: t ₁ of _one steel plate 10, that is, by appropriately selecting the size (diameter and height) of the small through-hole 15, sound absorbing and sound can be arbitrarily set the resonant frequency f ₁ of the damping panel 1, any component of the frequency f ₁ may be sound-absorbing.

Further, by appropriately selecting the diameter: d ₂ of the through hole 25 and / or the thickness: t ₂ of the resin plate 20, that is, appropriately selecting the volume V ₀ of the volume chamber 45, the vibration damping / sound absorbing panel 1. The resonance frequency f ₁ can be arbitrarily set, and the component of the arbitrary frequency f ₁ can be absorbed.

Then, both the size (diameter and height) of the small through-hole 15 and the volume V ₀ of the volume chamber 45 are appropriately selected, and the resonance frequency f ₁ of the vibration control / sound absorbing panel ₁ is arbitrarily set. it is also possible to absorbing the component of the frequency f ₁ of the.

Since the sound generated from the motor and the motor control device is a sound having a peak at a specific frequency as described above, the specific peak frequency and the resonance frequency f ₁ are the same so that d ₁ , By appropriately selecting d ₂ , t ₁ , and t _{2, it} is possible to obtain the sound absorption / vibration control panel 1 that absorbs a specific frequency component suitable for mounting around the motor and the motor control device.

The sound generated from the motor and the motor control device often has a peak in the high frequency range of 3 to 7 kHz. Therefore, as a sound absorption / vibration panel attached around the motor and the motor control device, the resonance frequency f ₁ is , Preferably in the range of 3 to 7 kHz.

The ability to absorb the frequency component of the resonance frequency f ₁ (hereinafter referred to as “sound absorption rate”) is determined through the small through hole 15 if the position where the sound absorbing / damping panel 1 is installed is the same distance from the sound source. The sound absorption coefficient of the sound absorbing / damping panel 1 is larger as the number of volume chambers 45 communicating with the space where the sound source exists is larger.

If the size of the sound absorbing and sound damping panel 1 are the same, shown in Figure 1, the shorter center distances P _1, the greater the number of volume chambers 45 in communication with, the sound absorption coefficient of the damping-absorbing panels 1 Becomes higher.

  It is preferable from the viewpoint of improving the sound absorption rate that all the volume chambers 45 communicate with a space where a sound source exists.

  When the level of the frequency component to be absorbed is small, the number of small through holes 15 provided in one steel plate 10 is reduced, and only some volume chambers 45 have noise sources through the small through holes 15. You may make it communicate with the space which is doing. In this case, the volume chamber 45 not communicating with the space where the noise source exists does not contribute to the sound absorption, but contributes to the weight reduction of the sound absorption / vibration control panel 1.

Incidentally, the thickness t ₃ of the other steel sheet 30, since it is not in the above formula (B), the thickness t ₃ of the other steel sheet 30 does not affect the sound absorption coefficient of the sound absorbing and sound damping panel 1, The vibration damping property by configuring the resin plate 20 as an intermediate layer and the sound insulating property by the high density two layers of the steel plate 10 and the steel plate 30 are superior to a normal single steel plate.

  Considering these characteristics, the sound absorbing / damping panel 1 can be used as a structural member having excellent vibration damping properties and sound insulation properties.

  Since the pair of steel plates 40 including one steel plate 10 and the other steel plate 30 has a laminated structure with the resin plate 20 sandwiched therebetween, when the sound absorbing / damping panel 1 is vibrated, the volume chamber 45 Since the resin plate 20 of other parts converts vibration energy into heat energy, the sound absorbing / damping panel 1 functions as a vibration damping material.

  Next, a second embodiment of the structural laminated steel sheet having sound absorbing properties of the present invention will be described. FIG. 4 is a front view of a multi-frequency sound absorbing / damping panel as a second embodiment of the structural laminated steel sheet having sound absorbing properties of the present invention. Reference numeral 2 in FIG. 4 indicates a multi-frequency sound absorbing / damping panel. In addition, the multi-frequency sound absorption here means to absorb a plurality of frequency components.

The multi-frequency sound absorbing / damping panel 2 has one steel plate 10, a small through hole 15, a resin plate 20, a through hole 25, the other steel plate 30, and a volume chamber 45 in the first embodiment. Common with the vibration panel 1. Incidentally, the small through holes 15 and the through-hole 20 is also common that they are disposed at a center-to-center distance P _1.

Multiple frequency sound absorbing and sound damping panel 2, in that it has a diameter d ₁ ^* of the small through holes 16, the diameter d ₂ ^* through holes 26 in the new, different from the sound absorbing and sound damping panel 1. The small through holes 16 and the through holes 26 of the multi-frequency sound absorbing / damping panel 2 are arranged at a center-to-center distance P ₂ (pitch P ₂ ). The following describes this different point.

Resonance frequency f ₂ of the Helmholtz resonator structure composed of a small through-hole 16 and the through-hole 26, from the formula (A) can be obtained as follows.
f ₂ = (c / 2π) × [S / {V ₀ × (t ₁ + d ₁ ^* / 2)}] ^1/2 (C)
Where S = {π (d ₁ ^* ) ² } / 4, V ₀ = πt ₂ × (d ₂ ^* / 2) ² , c: speed of sound

The multi-frequency sound absorbing / damping panel 2 is a Helmholtz resonator composed of a small through hole 15 and a through hole 25 and absorbs a component of frequency f ₁ and is composed of a small through hole 16 and a through hole 26. The Helmholtz resonator absorbs the frequency f ₂ component.

The multi-frequency sound absorbing / damping panel 2 is a panel that absorbs the components of the _two frequencies f ₁ and f ₂ , but has small diameters different from those of the small through holes 15 and 16 and the through holes 25 and 26. If a hole and a through-hole are arrange | positioned in a panel, the multi-frequency sound absorption and vibration suppression panel which absorbs three or more frequency components can be obtained.

  Since the motor and the motor control device may generate a sound having a peak at two or more frequencies, the product / multi-frequency sound absorbing panel 2 is suitable for mounting around the motor and the motor control device to absorb the sound. is there.

  Next, the manufacturing method of the structural laminated steel sheet having sound absorbing properties according to the present invention will be described by taking the sound absorbing / damping panel 1 according to the first embodiment as an example.

  FIG. 5 is a schematic longitudinal sectional view for explaining a method of manufacturing the sound absorbing / damping panel 1.

The resin plate 20 is subjected to drilling, and a plurality of through holes 25 are provided. In the case of the sound absorbing / damping panel 1, the through holes 25 are arranged at every center distance interval P ₁ .

  The method for drilling the resin plate 20 may be a conventional method and is not particularly limited. For example, punching.

One steel plate 10 is also subjected to drilling, and a plurality of small through holes 15 are provided. Small through holes 15 are also arranged at every center distance interval P _1.

The drilling method of one steel plate 10 may be a conventional method and is not particularly limited. For example, drilling, punching, laser processing, etching, and the like, but the resonance frequency f ₁ greatly affects the processing accuracy of the diameter d ₁ of the small through hole 15, so drilling or laser processing with high processing accuracy is performed. Is preferred.

Further, since the small through hole 15 is disposed by processing the steel plate, it is convenient for the small through hole 15 to have a small diameter and high accuracy. By making the aperture small, the resonance frequency f ₁ can be set high, and by making it highly accurate, there is little error in the resonance frequency f ₁ .

  Therefore, there are many cases where there is a peak in the high frequency range, and it is convenient to manufacture the sound absorbing / damping panel 1 for an electric motor and a motor control device in which the width of the peak generates a narrow sound.

  On the other hand, for example, in the case of the sound absorbing panel of Patent Document 2, the hole corresponding to the small through hole 15 in the present invention is disposed in the porous material, so that a small diameter and high precision hole is arranged. Since it is difficult to install, it is difficult to manufacture a sound absorbing panel that is applied to an electric motor and a motor control device that has a peak in a high frequency range and generates a narrow sound.

  As shown in FIG. 5A, the resin plate 20 provided with the plurality of through holes 25 is placed on the roller 70 and conveyed to move to the next step of forming a laminate. .

  FIG. 5B is a schematic longitudinal sectional view showing a process of forming a laminated body having a Helmholtz resonator structure.

  As shown in FIG. 5 (b), the position of the through hole 25 is detected by the position detecting means 71a while the resin plate 20 is being conveyed. Further, the position of the small through hole 26 disposed in one steel plate 10 is detected by the position detecting means 71b.

  The position information of the through hole 25 and the position information of the small through hole 15 are input and calculated to a control arithmetic device (not shown), and the through hole 25 and the small through hole 15 are based on the output result from the control arithmetic device. The resin plate 20 sandwiched between one steel plate 10 and the other steel plate 30 is fed between a pair of pressure-bonding rolls 72, and the one steel plate 10, the resin plate 20, and the other The steel plate 30 is pressure bonded to form a laminate.

  In the laminate, a volume chamber 45 is formed by a through hole 25 disposed in the resin plate 20 and a pair of steel plates 40 including one steel plate 10 and the other steel plate 30, and a small through hole 15. Thus, the volume chamber 45 is opened to the space opposite to the resin plate 20 with respect to the one steel plate 10 (the space above the one steel plate 10 in FIG. 5B). With this opening, a laminate having a Helmholtz resonator structure can be formed.

  In addition, in the superposition of the through hole 25 and the small through hole 15, it is necessary that the small through hole 15 completely overlaps the opposing through hole 25.

  In other words, it is necessary that at least a part of the small through hole 15 does not overlap with a part where the through hole 25 of the resin plate 20 is not provided.

When at least a part of the small through hole 15 overlaps a part of the resin plate 20 where the through hole 25 is not provided, a part of the small through hole 15 is blocked, and the diameter of the small through hole 15 is This is different from d _{1 in the} above equation (B), and as a result, the resonance frequency f ₁ is also different, and a desired frequency component cannot be absorbed.

  In addition, when the small through hole 15 and the through hole 25 do not overlap at all, there is no opening in the volume chamber 45, and a Helmholtz resonator structure cannot be obtained, so that a sound absorbing effect can be obtained. Can not.

  The center axis of the through hole 25 and the center axis of the small through hole 15 are preferably coincident with each other. However, if the above overlapping condition is satisfied, the center axis of the through hole 25 and the center of the small through hole 15 are satisfied. The axis does not necessarily coincide with the axis.

  In the present embodiment, the method of forming a laminate using a pressure roll is illustrated, but other methods may be used if a laminate having a Helmholtz resonator structure is obtained while satisfying the above overlapping conditions. For example, there is a method of pressure bonding using a press molding machine.

  The laminate is cut to a predetermined length by the cutting means 74, and the laminate cut plate 80 is formed. Although there is no restriction | limiting in particular in the cutting means 74, For example, there exists a shearing apparatus etc.

  The laminate cut plate 80 includes the resin plate 20 made of a thermosetting resin. In the next step, the laminate cut plate 80 is heated and the resin plate 20 is cured.

  The type of the thermosetting resin may be determined in consideration of the bondability between the pair of steel plates 40 and the resin plate 20 both before and after the thermosetting of the resin plate 20 and the processability of the through hole 25, and is particularly limited. There is no.

  FIG. 5C is a schematic longitudinal cross-sectional view showing a process of heating the laminate cut plate 80 to cure the resin plate 20 and bonding the resin plate 20 and the pair of steel plates 40 together.

  As shown in FIG. 5 (c), the laminated sheet cutting plate 80 is inserted into a heating furnace 76 to thermally cure the resin plate 20, thereby strengthening the bonding force between the pair of steel plates 40 and the resin plate 20. Paste them together.

  In the present embodiment, the heating furnace 76 is used as the heating means, but the present invention is not limited to this. For example, using an infrared device, one steel plate 10 and the other steel plate 30 are irradiated with infrared rays, and the resin plate 20 is thermoset by heat of the one steel plate 10 and the other steel plate 30 heated by infrared irradiation. You may let them.

  In addition, it is not preferable to bend the laminated body cutting plate 80 until thermosetting is completed. The laminate cut plate 80 before thermosetting does not have a strong bonding force between the pair of steel plates 40 and the resin plate 20, and the positional relationship between the small through holes 15 and the through holes 25 is distorted due to bending or the like. Because it will end up.

  Therefore, the length of the laminated sheet cutting plate 80 is not limited to the size of the vibration damping / sound absorbing panel 1 as a finished product, and is the size of the heating means (in the case of the present embodiment, the size of the heating furnace 76). The predetermined length is preferably determined in consideration of the transport method and the like.

  As described above, the sound absorbing / damping panel 1 is taken as an example to explain the manufacturing method of the structural laminated steel sheet having sound absorbing properties of the present invention. When the multi-frequency sound absorbing panel 2 of the second embodiment is manufactured, What is necessary is just to manufacture similarly to the sound-absorption / vibration control panel 1 if the process of arrange | positioning the through-hole 16 and the small through-hole 26 of a diameter different from the through-hole 15 and the small through-hole 25 is added.

  Next, the present invention will be further described with reference to examples. Conditions in the examples are one example of conditions adopted to confirm the feasibility and effects of the present invention, and the present invention is examples of these one condition. It is not limited to. The present invention can adopt various conditions as long as the object of the present invention is achieved without departing from the gist of the present invention.

6 types of panels having the same structure as the vibration damping / sound absorbing panel 1 shown in FIG. 1 (panels No. 1 to No. 6), the same as the vibration damping / multiple frequency sound absorbing panel 2 shown in FIG. Three types of panels having the structure (panels No. 7 to No. 9) were prepared. The size of each panel is
1400 mm × 850 mm.

In each panel, the plate thickness t _{1 of one} steel plate 10, the plate thickness t ₂ of the resin plate 20, the plate thickness t ₃ of the other steel plate 30, the diameter d ₁ of the small through hole 15, the diameter d _{2 of the} through hole, the center between distances _{P 1,} respectively shown in table 1. Panel No. 7-No. For 9, the diameter _d ¹ of the small through hole 16 ^*, the diameter _d ² of the through hole 26 ^*, also the center-to-center distance _{P 2,} are shown in Table 1.

  The number of small through holes 15 in each panel is shown in Table 2 (continuation of Table 1). Since all the small through holes 15 and the through holes 25 are overlapped, the numbers of the small through holes 15 and the through holes 25 are the same. Panel No. 7-No. For 9, the numbers of small through holes 16 and through holes 26 are also shown. The numbers of the small through holes 16 and the through holes 26 are the same.

  That is, the number of small through holes 15 and the number of small through holes 16 mean the number of Helmholtz resonators of each panel.

Table 2 shows the resonance frequency f ₁ of each panel. Panel No. 7-No. For 9, the resonance frequency _{f 2} are also shown in Table 2.

The sound absorption rate was evaluated in the following manner. _A sound source that generates sound of frequency f _A is installed in the reverberation room, separated from the panel by 1 m, and further connected from the surface of the sound source to the panel with a φ2.0 mm piano wire. The loudness was measured in an anechoic room on the opposite side of the panel from the panel, and the noise reduction rate was calculated from the difference in sound pressure.

Panel No. 7-No. For 9, at the same time from the sound source for generating a sound of a frequency f _A, it was determined noise reduction rate in the same manner by generating a sound of a frequency f _B.

As a comparative example, panel no. 1-No. The steel plate thickness is 0.8 mm (the thickest t ₁ + t ₃ is 0.8 mm among the panels No. 1 to No. 9) and 1.6 mm (panel Nos. _{1 to} No. 9). in 9, panel thickest _{t 2} is pasted the polyurethane foam of 1.6mm) to the noise source side No. 10 was manufactured, and a sound source that generates sounds of frequencies f _A and f _B was installed, and the noise reduction rate was similarly obtained.

  The results are shown in Table 2.

As is apparent from Table 2, the panel No. 1-No. 9 is a panel having respective resonance frequencies f ₁ and f ₂ corresponding to the frequencies f _A and f _B of the sound source, and 9 dB or more depending on the number of Helmholtz resonators (number of small through holes 15 and 16). It was confirmed that the noise reduction rate was achieved.

On the other hand, panel No. which is a comparative example. 10, it was confirmed that the noise reduction rate remained at 8 dB for both the frequencies f _A and f _{B of} the sound source.

  In addition, the place mentioned above is only what illustrated embodiment of this invention, and this invention can add a various change within the description range of a claim.

  For example, a porous sound-absorbing material is used as a sound-absorbing / damping panel for a vehicle in which a porous sound-absorbing material is attached to the structural laminated steel sheet having sound-absorbing properties of the present invention and both an internal combustion engine and an electric motor are mounted. In the laminated steel sheet for structural use having the sound absorbing properties of the present invention, the sound absorbing sound generated from the internal combustion engine and a part of the specific frequency component of the sound generated from the motor and the motor control device are absorbed. The sound absorbing material absorbs the remaining part of the specific frequency component of the sound generated from the motor and the motor control device that could not absorb the sound completely (the small sound remaining without being absorbed by the same frequency). By doing so, a sound in a wide frequency band may be absorbed more completely.

  As described above, according to the laminated steel sheet for sound absorption of the present invention, a large space for sound absorption is not required, and both sound and vibration are used without using a porous sound absorbing material. The structural laminated steel sheet having sound absorbing properties according to the present invention is arranged around the generation source to absorb the sound of the specific frequency component and simultaneously absorb the vibration. The present invention has high utility value industrially.

  In addition, according to the method for manufacturing a structural laminated steel sheet having sound absorption characteristics of the present invention, since a large amount of porous sound absorbing material is not used, the material cost of the porous sound absorbing material is not necessary. Since the man-hour for attaching the sound absorbing material to the member is unnecessary, it is possible to obtain a sound-absorbing structural laminated steel sheet having both sound-absorbing properties and vibration-damping properties at a low cost, and there is an industrially significant effect. it can.

DESCRIPTION OF SYMBOLS 1 Sound absorption / damping panel 2 Multi-frequency sound absorption / damping panel 10 One steel plate 15, 16 Small through-hole 20 Resin plate 25, 26 Through-hole 30 Other steel plate 40 A pair of steel plates 45 Volume chamber 50 Helmholtz type resonator 51 Volume Chamber 55 Opening 56 Sound source 70 Rollers 71a, 71b Position detecting means 72 Crimp roll 74 Cutting means 76 Heating furnace 80 Laminate cutting plate

Claims (2)

A laminated laminated steel sheet used as a sound absorbing panel to be mounted around an electric motor and an electric motor control device, and having a laminated structure in which a resin plate is sandwiched between a pair of steel plates composed of one steel plate and the other steel plate In steel plates,
The resin plate has a plurality of through holes, and the through holes and the pair of steel plates form a plurality of volume chambers,
In one or all of the plurality of volume chambers, the one steel plate has a plurality of small through holes smaller than the plurality of through holes,
A part or all of the plurality of volume chambers communicates with the space on the opposite side of the one steel plate through the plurality of small through holes,
The laminated structure has a Helmholtz type resonator structure that absorbs a specific frequency component of 3 to 7 kHz among sounds generated from a sound source existing on the small through hole side. Laminated steel sheet. A laminated laminated steel sheet used as a sound absorbing panel to be mounted around an electric motor and an electric motor control device, and having a laminated structure in which a resin plate is sandwiched between a pair of steel plates composed of one steel plate and the other steel plate In the manufacturing method of the steel sheet,
The resin plate is subjected to a drilling process to dispose a plurality of through holes;
The one steel plate is subjected to a drilling process, and is provided with a plurality of small through holes smaller than the plurality of through holes;
While superposing the plurality of through holes and the plurality of small through holes, the resin plate is sandwiched between the pair of steel plates, and a volume chamber is formed by the inside of the through holes and the pair of steel plates. Opening the volume chamber to the space on the opposite side of the one steel plate with the small through hole to form a laminate having a Helmholtz resonator structure;
Cutting the laminate to a predetermined length to form a laminate cut plate;
The structure having sound-absorbing property according to claim 1 , further comprising a step of heating the laminate cut plate, curing the resin plate, and bonding the resin plate and the pair of steel plates. For producing laminated steel sheets for automobiles.

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