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JP2002016997

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This translation is machine-generated. It cannot be guaranteed that it is intelligible, accurate,
complete, reliable or fit for specific purposes. Critical decisions, such as commercially relevant or
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DESCRIPTION JP2002016997
[0001]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a
diaphragm in which an edge portion and a body portion are integrally formed, and a method of
manufacturing the same.
[0002]
2. Description of the Related Art FIG. 11 is a cross-sectional view showing an example of a
speaker, 1 being a diaphragm, 2A being an edge portion of the diaphragm 1, 3A being a body
portion, 50 being a voice coil bobbin, 51 being a magnetic circuit, 52 Is a frame.
[0003]
The edge portion 2A of the outer periphery of the diaphragm 1 is fixed to the frame 20, and a
center hole 1A is provided at the center of the body portion 3A to be coupled to the voice coil
bobbin 50. The board 1 vibrates and emits a sound.
[0004]
In the case of a cone type diaphragm, the rigidity of the body portion 3A is high, and the edge
portion 2A is softened so as to follow the amplitude of vibration.
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1
Therefore, conventionally, as shown in FIG. 12 (an enlarged view of X in FIG. 11), the edge
portion 2A is formed of urethane foam or the like, and is bonded to the body portion 3A by an
adhesive.
[0005]
However, since the conventional diaphragm has the edge and the body bonded together by an
adhesive, the adhesive strength is weak and the edge and the body are integrated. Since it is
formed, the number of parts also increases.
In addition, although there is a diaphragm in which the edge part and the body part are
integrated with the same material, the rigidity difference between the edge part and the body
part is difficult to adjust, and the compliance of the edge can not be sufficiently obtained. It was
[0006]
An object of the present invention is to provide a lightweight and robust diaphragm which can
freely adjust the rigidity of the edge portion and the body portion, and a method of
manufacturing the same.
[0007]
According to the invention of claim 1, it is a diaphragm in which an edge portion and a body
portion are integrally formed, wherein the edge portion is formed of an unfoamed layer, and the
body portion is formed. Is formed by the foam layer.
[0008]
In the invention of claim 2, a non-foamed layer is formed on the surface of the foam layer of the
body portion to form a three-layer structure.
In the invention of claim 3, the thickness of the body portion is larger than the thickness of the
edge portion.
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2
[0009]
In the invention of claim 4, the diaphragm is of a cone type.
According to the fifth aspect of the present invention, the diaphragm is a diaphragm in which the
edge portion and the body portion are integrally formed, wherein the edge portion is formed of a
foam layer, and the body portion is formed of an unfoamed layer.
[0010]
In the invention of claim 6, the non-foamed layer is formed on the surface of the foam layer of
the edge portion to form a three-layer structure. In the invention of claim 7, the thickness of the
body portion is smaller than the thickness of the edge portion. In the invention of claim 8, the
diaphragm is dome-shaped.
[0011]
In the invention of claim 9, a resin containing a foaming agent is injected into a mold, and the
mold is opened after a predetermined time has elapsed after completion of injection filling, so
that the foam area of the body portion and the edge portion A method of manufacturing a
diaphragm by a foam molded body having an unfoamed area according to claim 1, wherein the
cavity of the mold has a thick space corresponding to the foam area and a thin space
corresponding to the unfoamed part, The time is set until the resin filled in the thin-walled space
is cured and the resin filled in the thick-walled space is not cured.
[0012]
In the invention of claim 10, the resin containing the foaming agent is injected into the mold, and
the mold is opened after a predetermined time has elapsed after completion of injection filling, so
that the foam area of the edge portion and the body portion A method of manufacturing a
diaphragm by a foam molded body having an unfoamed area according to claim 1, wherein the
cavity of the mold has a thick space corresponding to the foam area and a thin space
corresponding to the unfoamed part, The time is set until the resin filled in the thin-walled space
is cured and the resin filled in the thick-walled space is not cured.
[0013]
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3
In the invention of claim 11, the mold reduces the clamping force after the lapse of the
predetermined time.
In the invention of claim 12, the foamed region has a three-layer structure in which the inside is
a foamed layer and the surface is a non-foamed layer, and the foamed region has a one-layer
structure of the non-foamed layer.
[0014]
BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will
be described with reference to FIG.
FIG. 1 (A) is a partial cross-sectional view of a diaphragm according to an embodiment of the
present invention, and FIG. 1 (B) is an enlarged view of a portion X of FIG. 1 (A).
[0015]
In FIG. 1A, reference numeral 1 denotes a diaphragm, and an edge portion 2A is integrally
formed on the outer periphery of the diaphragm 1, and a body portion 3A is integrally formed on
the inner periphery thereof. As shown in FIG. 1 (B), the edge portion 2A is formed of the skin
layer 2A of the non-foamed layer, the body portion 3A has a three-layer structure of the foam
layer 3 inside and the skin layer 2 of the non-foam layer It is formed.
[0016]
Next, prior to describing the method of producing the diaphragm of the present invention, a
method of producing a foamed molded article having a three-layer structure in which the whole
is a foamed area will be described with reference to FIG. The relationship between the time from
the resin filling to the opening of the mold and the finished foam molded body, which serves as a
basis for forming a region and an unfoamed region separately, will be described based on FIGS. 3
to 4.
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[0017]
In FIG. 2, reference numeral 20 denotes a mold, and the mold 20 is constituted of a movable
mold 21 and a fixed mold 22. The movable mold 21 and the fixed mold 22 constitute a cavity 6.
The mold clamping force is controlled by a mold clamping pressure control unit (not shown) for
the movable mold 21 and the fixed mold 22. The cavity 6 is uniform in thickness and width,
whereby a foam of uniform width is formed. First, as shown in FIG. 2A, the resin 7 containing a
foaming agent is injected into the cavity 6 and filled in the cavity 6 as shown in FIG. 2B.
[0018]
In this state, curing starts from the portion in contact with the mold 20 and a skin layer is
formed, but the mold clamping pressure is applied to the mold 20 by the mold clamping pressure
control unit. Since the gas of the decomposed blowing agent is compressed at the molten portion
of the resin inside the cavity 6, the foaming is suppressed. Thereafter, after a predetermined time
has passed and the skin layer is formed to an appropriate thickness, when the mold clamping
pressure is dropped and the mold is opened, the molten portion of the resin inside the cavity 6 is
promoted to be foamed and formed as a foamed layer Ru. As described above, a foam molded
article having a three-layer structure in which the surface is a skin layer and the inside is a foam
layer is formed.
[0019]
In forming the three-layered foamed molded product, the foamed molded product produced by
changing the time from completion of injection to the mold 20 to opening of the molded mold 20
is as follows. First, as shown in FIG. 3, when the movable mold 21 is opened within the time t1
after filling, as shown in FIG. A three-layer structure with large and thick cells is formed.
[0020]
When the movable mold 21 is opened within the time t1 to t2 shown in FIG. 3, as shown in FIG.
4B, the thickness of the skin layer 2 becomes thicker than in the case of FIG. 4A, and the inside
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5
Also, a three-layer structure in which the foam layer 3 is formed is formed. This state is most
preferable as a foam molded article.
[0021]
Next, when the movable mold 21 is opened within the time t2 to t3 shown in FIG. 3, as shown in
FIG. 4C, the thickness of the skin layer 2 is further increased and the melted portion is reduced.
Therefore, the portion where the foaming power remains is foamed by a predetermined amount
to be a foamed layer, but the portion where the foaming power is weak is cured as it is.
[0022]
Further, when the movable mold 21 is opened after time t3 shown in FIG. 3, as shown in FIG. 4
(D), only the skin layer 2 is formed since almost the whole is hardened. Thus, by lengthening the
time from the completion of injection to the release of the mold, the skin layer 2 is formed
thicker, and if the thickness of the cavity 6 is changed, the entire inside of the cavity hardens
from the completion of injection and only the skin layer The time to obtain a single-layered
molded body comprising The manufacturing method of the present invention is made utilizing
this phenomenon, and the principle thereof will be described with reference to FIG. 5 and FIG.
[0023]
FIG. 5 shows a diaphragm mold 20 which simultaneously forms the foam area 4 and the nonfoam area 5. As shown in FIG. 5, the thickness 6A of the portion corresponding to the foamed
area 4 (body part 3A) described in FIG. 1 corresponds to the non-foamed area 5 (edge portion
2A) in the cavity 6 of the mold 20. Make the part thicker than 6B.
[0024]
When the resin 7 containing a foaming agent is filled in the cavity 6 of such a mold 20, the state
shown in FIG. 6 is obtained with the passage of time. The thickness 0.1 mm in FIG. 6 corresponds
to 6B in FIG. 5, and the thickness 0.2 mm corresponds to the thickness 6A in FIG. The times t1, t2
and t3 in the states of (A), (B), (C) and (D) of FIG. 4 described above are related to the thickness of
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6
the cavity 6 and relatively increase as the thickness increases. The time will be longer.
[0025]
That is, with respect to the times t1, t2 and t3 for the thickness of 0.1 mm shown in FIG. 6, in the
case of the thickness of 0.2 mm, t1 ', t2' and t3 'are obtained. Therefore, the non-foamed region 5
of thickness 6B in FIG. 5 is after t3 after which the whole is cured to form a single layer structure
of the skin layer, and the foamed region 4 of thickness 6A is the skin layer and the foam layer By
opening the movable mold 21 during the time t2 '(formed between A and B in FIG. 6) formed as a
preferred three-layer structure of the foam molded body 1 in the state shown in FIG.
[0026]
Next, with reference to FIGS. 7 and 8, an embodiment in which the diaphragm 1 of the speaker is
formed of a foam molded body using the mold 20 shown in FIG. 5 will be described.
[0027]
FIG. 7 shows an injection molding machine for producing a diaphragm 1 of a speaker by a foam
molding.
The clamping pressure between the movable mold 21 held by the movable platen 24 of the mold
20 and the fixed mold 22 held by the fixed platen 25 in the injection molding machine shown in
FIG. It is controlled by the clamped cylinder 10.
[0028]
An injection port of an injection device 40 for injecting a resin mixture material obtained by
adding a foaming agent to PP (polypropylene) is inserted into the injection port of the fixed mold
22. The injection device 40 is controlled by the injection conditions controlled by the injection
process control unit 31. Further, information on the molding process is output from the injection
device 40 side, and the mold clamping pressure by the mold clamping pressure control unit 30
according to the information and information on the distance on the movable platen 24 side, etc.
Control is performed.
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[0029]
Subsequently, a method of manufacturing the diaphragm by the injection molding machine
having the above-described configuration will be described. First, as shown in FIG. 8A, the
movable mold 21 and the fixed mold 22 of the mold 20 are closed by the mold clamping
mechanism 10, and a resin mixture in which a foaming agent is put in PP (polypropylene) from
the injection device 40 Inject the material.
[0030]
At this time, the temperature of the resin mixture is maintained at about 240.degree. Also, the
temperature of the cavity surface of the mold 20 is maintained at about 90.degree. Furthermore,
the clamping pressure by the mold clamping cylinder 10 controlled by the mold clamping
pressure control unit 30 is maintained at about 100 t. Furthermore, the thickness of the cavity
formed by the movable mold 21 and the fixed mold 22 of the mold 20 is about 0.22 mm for the
foamed part and about 0.1 mm for the unfoamed part.
[0031]
At this time, as shown in FIG. 6B, the resin mixture filled in the cavity between the movable mold
21 and the fixed mold 22 solidifies from the portion in contact with the mold 20. Begins to form
the skin layer 2, and the melted part is pressed by the pressure from the screw and the clamping
pressure by the movable mold 21 and the fixed mold 22, the gas of the decomposed blowing
agent is compressed and solidified while suppressing the foaming Is moving forward.
[0032]
Next, as shown in FIG. 6C, immediately after the resin mixture is completely filled, the foaming
pressure of the foaming agent at the melting portion has a force to expand the surrounding skin
layer (solidified portion) 2. In the meantime, the clamping pressure by the mold clamping
cylinder 10 controlled by the mold clamping pressure control unit 30 is instantaneously dropped
to nearly 0 t.
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As a result, the compressed blowing agent decomposition gas of the melted portion expands
while spreading the resin around, and foaming starts.
[0033]
Here, the mold opening timing of the movable mold 21 will be described. If the mold opening is
performed before the resin filling is completely completed, the resin mixture excessively enters
the inside of the movable mold 21 of the mold 20 and the cavity of the fixed mold 22 and the
weight of the product becomes heavy. Conversely, if the timing is late, solidification of the resin
proceeds too much, and the foaming agent is completely solidified without being able to foam.
[0034]
Therefore, as described in FIG. 6, the unfoamed area 5 is cured, and in the foamed area 4, the
mold opening is performed after 0.10 to 0.15 seconds, which is the time period AB during which
good foaming is performed. Is preferred. However, these requirements vary depending on
conditions such as the resin temperature of the resin mixture, the temperature of the mold 20,
the product thickness, and the amount of the foaming agent added.
[0035]
The opening amount of the mold 20 is about 0.5 mm, and by opening the mold by 0.5 mm, a
foam of 0.5 mm and a non-foamed part of 0.1 mm similar to the mold can be obtained. Also, the
foaming agent, the force of the spring and the clamping pressure are controlled so that the
opening speed of the mold is 0.5 mm and opened at 0.20 seconds, that is, about 2.5 mm / s.
[0036]
Furthermore, if a spring is embedded between the movable mold 21 and the fixed mold 22 of the
mold 20 to increase the opening force of the movable mold 21 when the clamping pressure is
lowered, the expansion ratio is increased. You can raise it.
[0037]
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9
Here, specific examples of the injection molding machine and the foaming agent adopted in this
embodiment will be described. As PP (polypropylene), 5% of glass fiber and 5% of mica are added
to MA04 Mitsubishi Chemical Co., Ltd. As a foaming agent, the thing of EE-206 Eiwa Chemical
Industry Co., Ltd. was used, and the compounding ratio made the foaming agent 0.1 weight ratio
using what was used.
Further, the thickness of the cavity of the mold was 0.30 mm for the portion 6A corresponding to
the foamed area 4 and 0.15 mm for the portion 6B corresponding to the unfoamed area. As the
injection molding machine, Ultra 220 Sumitomo Heavy Industries, Ltd. was used.
[0038]
According to the method of forming a foam molded article as described above, the foamed area 4
is foamed to a thickness of about 1.7 times to a thickness of 0.50 mm, and the unfoamed area 5
is 0.15 mm. A conical cone shape is obtained. The foamed area 4 has a three-layer structure in
which a skin layer is formed on the surface and a foamed layer is formed in the inside, while the
unfoamed area 5 is formed in a one-layer structure of the skin layer.
[0039]
Thus, in this embodiment, a foaming agent is introduced from the injection device 40 into PP
(polypropylene) in the cavity between the fixed mold 21 and the movable mold 22 to which the
mold clamping pressure is applied. After the resin mixture material was injected, the pressure
was dropped between the fixed side mold 21 and the movable side mold 22 to open the mold
and cause the foaming agent to foam.
[0040]
Accordingly, since the foam molded diaphragm can be obtained by the foaming of the foaming
agent added to the resin for the speaker diaphragm, the specific gravity is lowered, and therefore,
weight reduction can be achieved without lowering the rigidity.
[0041]
Although the spring is used to open the movable mold 21 in the embodiment, it may be opened
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mechanically.
In the embodiment, the resin is injected and filled in a closed state of the mold 20. However, a
predetermined amount is opened before the injection of the resin, and the resin is injected in a
predetermined amount, and then the mold is closed and filled. After that, the mold may be
reopened and the resin may be foamed.
By doing so, the resin can be uniformly filled even at a thin thickness and distortion is eliminated.
[0042]
In the embodiment, as described with reference to FIG. 5, the foam area and the non-foam area
are also movable in the cavity 6 of the mold 20. However, as shown in FIG. Alternatively, only the
portion 21B may be movable, and the portion 21B serving as the foam area may be opened
between the times t1 and t2 described in FIG.
[0043]
Also, although the above description has been given with respect to the cone type diaphragm, in
the case of the soft dome type diaphragm using a soft material, as shown in FIG. 10, the soft
dome type diaphragm 60 is The portion 62 and the edge portion 61 may be integrally formed by
the method described above, and the body portion 62 may be formed of an unfoamed layer, and
the edge portion 61 may be formed of a foamed layer.
By thus increasing the rigidity of the edge portion 61, the lowest resonance frequency can be
increased.
[0044]
The edge portion of the diaphragm is formed of the non-foamed layer, and the body portion is
integrally formed of the foam layer, so that the rigidity of the edge portion and the body portion
is also changed by changing the thickness. It is possible to obtain a robust and lightweight
diaphragm that can be freely adjusted.
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[0045]
Brief description of the drawings
[0046]
1 is a partial cross-sectional view of a diaphragm of an embodiment of the present invention.
[0047]
2 is a cross-sectional view of a mold for explaining the principle of the present invention.
[0048]
3 is a time scale diagram for explaining the principle of the present invention.
[0049]
4 is a resin cured state explanatory view for explaining the principle of the present invention.
[0050]
5 is a partial sectional view of the mold of the present invention.
[0051]
6 is a diagram for explaining the time to open the mold of the present invention.
[0052]
7 shows an injection molding machine according to an embodiment of the method of molding a
foam molded article of the present invention.
[0053]
<Figure 8> It is the figure in order to explain the formation method of the speaker diaphragm.
[0054]
<Figure 9> It is the figure which shows the other execution example of the die of this invention.
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12
[0055]
10 is a cross-sectional view of a diaphragm of another embodiment of the present invention.
[0056]
11 is a cross-sectional view of the speaker.
[0057]
12 is a cross-sectional view of a conventional diaphragm.
[0058]
Explanation of sign
[0059]
1, 60 diaphragm 2 skin layer (non-foamed layer) 2A, 61 edge portion 3 foam layer 3A, 62 body
portion 4 foam region 5 unfoamed region 6 cavity 7 resin 20 mold 21 movable mold 22 fixed
mold
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