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DESCRIPTION JP2004048222

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DESCRIPTION JP2004048222
The object is to provide a speaker frame which is lightweight and has excellent strength, internal
loss and S / N ratio. A speaker frame of the present invention is formed of a composite material
containing an aluminum alloy and a ceramic. Preferably, the ceramic is selected from the group
consisting of silicon carbide, alumina, aluminum nitride, silica, titanium oxide, zinc oxide,
magnesium hydroxide, barium carbonate, calcium silicate, talc, clay, mica, boron nitride and
silicon nitride Ru. [Selected figure] None
スピーカーフレーム
TECHNICAL FIELD The present invention relates to a speaker frame. More particularly, the
present invention relates to a speaker frame that is lightweight and has excellent strength,
internal loss and signal to noise ratio. A speaker frame plays the role of accurately holding the
position of a vibration system (diaphragm and voice coil) and a support system (edge and
damper) with respect to a magnetic circuit consisting of a magnet and iron. Have. That is, the
speaker frame is required to have rigidity as a skeleton of the speaker unit. Although cast iron,
carbon steel, an aluminum alloy, a synthetic resin etc. are used as a material of such a speaker
flame | frame, each has a problem. A speaker frame made of cast iron or carbon steel has
excellent rigidity but has a small internal loss, so that the frame itself tends to resonate in a high
frequency region. As described above, the frame itself emits unnecessary resonance sound, so
that the S / N ratio of the obtained speaker becomes insufficient. Furthermore, in view of
environmental problems etc., weight reduction is required particularly for in-vehicle speakers,
but cast iron and carbon steel can not cope with weight reduction because they are heavy.
Aluminum alloy seems to be suitable for weight reduction because of its low density, but its
strength (especially bending strength) is insufficient compared to cast iron etc., so it is necessary
to increase its thickness, resulting in weight reduction It is difficult. Furthermore, since the
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aluminum alloy also has a small internal loss as with cast iron and the like, there is a problem
that the S / N ratio of the obtained speaker is insufficient. The problem of S / N ratio can be
improved because the internal resin loss is larger than that of metal, but the elastic modulus and
impact resistance are small, and it is necessary to obtain practically acceptable rigidity as a
speaker unit frame. Is difficult. As described above, a speaker frame that is lightweight and has
excellent strength, internal loss and S / N ratio is strongly desired. SUMMARY OF THE
INVENTION The present invention has been made to solve the above-mentioned conventional
problems, and the object of the present invention is to achieve light weight and excellent
strength, internal loss, and the like. It is an object of the present invention to provide a speaker
frame having an S / N ratio. The speaker frame of the present invention is formed of a composite
material containing an aluminum alloy and a ceramic.
In a preferred embodiment, the ceramic is silicon carbide, alumina, aluminum nitride, silica,
titanium oxide, zinc oxide, magnesium hydroxide, barium carbonate, calcium silicate, talc, clay,
mica, boron nitride and silicon nitride It is selected from the group consisting of In a preferred
embodiment, the composite material contains silicon carbide in a proportion of 15% by volume to
55% by volume. In a preferred embodiment, the composite material contains alumina in a
proportion of 50% by volume to 60% by volume. In a preferred embodiment, the composite
material contains aluminum nitride in a proportion of 50% by volume to 70% by volume.
DETAILED DESCRIPTION OF THE INVENTION The speaker frame of the present invention is
formed of a composite material containing an aluminum alloy and a ceramic. The aluminum alloy
refers to an alloy containing aluminum (Al) as a main component. Here, "main component" refers
to a component contained in an amount of 50% by weight or more in the alloy. The aluminum
alloy preferably contains aluminum in a proportion of 70% by weight or more, more preferably
80% by weight or more, and most preferably 90% by weight or more. It is because weight
reduction and an excellent elastic modulus can be achieved simultaneously by combining with
other metals and the like. Examples of other metals contained in the aluminum alloy include
copper (Cu), magnesium (Mg), nickel (Ni), chromium (Cr), manganese (Mn) and zinc (Zn).
Furthermore, the aluminum alloy may contain nonmetallic elements such as silicon (Si). These
metals and / or nonmetal elements may be used alone or in combination as appropriate
depending on the purpose. The composition of a preferred aluminum alloy is as follows (units
are% by weight): Al / Cu / Si / Mg / Ni = 84.7 / 1.1 / 12.0 / 1.1 / 1.1 (4000 series), Al / Mg / Cr =
97.25 / 2.5 / 0.25 (5000 series), Al / Cu / Mn = 98.58 / 0.12 / 1.3 (3000 series), Al
/Si/Mg=98.95/0.45/0.6 (6000 series), and Al / Cu / Mg / Zn / Cr = 90.1 / 1.6 / 2.5 / 5.6 / 0 .2
(7000 series). Particularly preferred aluminum alloys are 4000 series and 5000 series.
It is because it is especially excellent in the balance of weight and an elasticity modulus.
Examples of ceramics used for the composite material in the present invention include silicon
carbide, alumina, aluminum nitride, silica, titanium oxide, zinc oxide, magnesium hydroxide,
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barium carbonate, calcium silicate, talc, clay, mica, nitrided Boron and silicon nitride can be
mentioned. Preferably, they are silicon carbide, alumina, aluminum nitride, silica, titanium oxide,
talc, clay and silicon nitride, more preferably silicon carbide, alumina, aluminum nitride, silica,
titanium oxide and silicon nitride, most preferably , Silicon carbide, alumina, and aluminum
nitride. This is because the improvement of internal loss is particularly remarkable. These
ceramics may be used alone or in combination of two or more. Preferably, the ceramic is a
powder. More preferably, the particle size of the ceramic powder is 0.5 to 3.0 μm. The content
of the ceramic in the composite material may vary depending on the type of the ceramic. For
example, silicon carbide is contained in the composite material in a proportion of preferably 15%
by volume to 55% by volume, more preferably 25% by volume to 45% by volume. For example,
alumina is contained in the composite material in a proportion of preferably 50% by volume to
60% by volume, more preferably 55% by volume to 60% by volume. For example, aluminum
nitride is contained in the composite material in a proportion of preferably 50% by volume to
70% by volume, more preferably 55% by volume to 65% by volume. When the ceramic content is
smaller than such a range, the effect of the internal loss improvement is often insufficient. When
the ceramic content is larger than such a range, the elastic modulus (in particular, flexural
modulus) is often insufficient. The method for producing the speaker frame of the present
invention is not particularly limited, and any suitable production method may be employed.
Typical manufacturing methods include casting (eg, sand casting, precision casting, die casting),
non-pressure metal penetration. The casting method is a method of mixing a ceramic with a
molten aluminum alloy to prepare a molten liquid, and pouring the molten liquid into a mold
having a predetermined shape. Non-pressure metal infiltration is a method in which a molten
aluminum alloy is infiltrated into a preformed ceramic. Hereinafter, the operation of the present
invention will be described. According to the present invention, by forming the speaker frame
from the composite material containing the aluminum alloy and the ceramic, it is possible to
obtain a speaker frame which is light in weight and has excellent strength, internal loss and S / N
ratio.
More specifically, by alloying the main component aluminum with a specific metal or nonmetallic
element, a specific ceramic (particularly, a ceramic powder) disperses very well in the alloy.
Therefore, internal friction between the aluminum alloy and the ceramic occurs very efficiently
when vibrating. As a result, the internal loss is increased, and the generation of the resonance
noise which is a problem in the case of the aluminum alloy alone can be solved, so that the S / N
ratio can be finally improved. Furthermore, since the ceramic functions well as a reinforcing
material, the problem of insufficient strength of the aluminum alloy can be solved, and as a
result, the contradictory requirements of weight reduction and strength can be simultaneously
satisfied. EXAMPLES The present invention will be specifically described by way of the following
examples, but the present invention is not limited to these examples. Example 1 A 4000 series
aluminum alloy was melted at about 700 ° C. The molten aluminum alloy was mixed with silicon
carbide to prepare a molten liquid. The mixing ratio of the aluminum alloy to silicon carbide was
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70/30 (volume%). The obtained melt was poured into a mold having a predetermined shape to
obtain a speaker frame. The density, elastic modulus and loss factor (internal loss) of the
obtained speaker frame were measured by a conventional method. The results are shown in
Table 1 together with the results of Examples 2 to 3 and Comparative Examples 1 to 3 described
later. <Example 1> <Example 2> (Example 2) Mix of 5000 series aluminum alloy and alumina
powder at 40/60 (volume%) did. The mixture was molded using a non-pressured metal
permeation method at 700-900 ° C. in a nitrogen atmosphere to obtain a speaker frame. The
obtained speaker frame was subjected to the same evaluation as in Example 1. The results are
shown in Table 1 above. Example 3 A 5000 series aluminum alloy and aluminum nitride were
mixed at 30/70 (volume%). The following procedure was performed in the same manner as in
Example 2 to obtain a speaker frame. The obtained speaker frame was subjected to the same
evaluation as in Example 1. The results are shown in Table 1 above. Comparative Example 1 A
speaker frame was obtained in the same manner as in Example 1 except that silicon carbide was
not added. The obtained speaker frame was subjected to the same evaluation as in Example 1.
The results are shown in Table 1 above. Comparative Example 2 The iron compound of FC 250
series was melted at about 1500 ° C. The molten iron compound was poured into a mold of a
predetermined shape to obtain a speaker frame. The obtained speaker frame was subjected to the
same evaluation as in Example 1. The results are shown in Table 1 above. Comparative Example
3 A speaker frame was obtained by sequentially pressing the carbon steel of S55C with a mold
having a predetermined shape. The obtained speaker frame was subjected to the same evaluation
as in Example 1. The results are shown in Table 1 above. As apparent from Table 1, the speaker
frame of the present invention has a very good balance of density (weight), elastic modulus and
loss coefficient as compared with the conventional speaker frame (Comparative Examples 1 to 3)
I understand that Specifically, although the speaker frame of Examples 1 to 3 has a density
slightly larger than that of Comparative Example 1, both the elastic modulus and the loss
coefficient are significantly superior. In comparison with Comparative Example 2, Example 1 is
equal to or more than Example 2 and Example 2 is about twice as good in elastic modulus, and
Example 2 is slightly inferior to Example 1 in the loss coefficient. It has become remarkably
superior. With regard to density, weight reduction of 1/2 or less has been achieved in any of the
examples. Compared with Example 3, with regard to the elastic modulus, although Example 1 is
slightly inferior, Examples 2 and 3 are equal to or more than each other, and the loss coefficient
is remarkably superior in all Examples. There is. With regard to density, weight reduction of 1/2
or less has been achieved in any of the examples. As described above, according to the present
invention, by forming a speaker frame from a composite material containing an aluminum alloy
and a ceramic, it is lightweight and has excellent strength, internal loss and A speaker frame
having an S / N ratio is obtained.
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