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JP2003078998

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DESCRIPTION JP2003078998
[0001]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a
support system component for an electroacoustic transducer such as an edge or a damper for
supporting a diaphragm such as a speaker or a microphone.
[0002]
2. Description of the Related Art As an edge of an electroacoustic transducer such as a speaker,
for example, the linearity with respect to the input is good, the reverse resonance phenomenon
does not easily occur, the weight is light, the manufacture is easy and inexpensive And the like.
[0003]
From such a point of view, as the material of the free edge where the diaphragm main body and
the edge portion are different materials, the vulcanized rubber edge is flexible and excellent in
vibration absorption, high in bending fatigue resistance, and also in heat resistance. It is used
relatively often because it is high and waterproof.
[0004]
However, recently, measures against environmental problems also tend to be emphasized from
the viewpoint of the global environment, but this vulcanized rubber edge is difficult to recycle,
and the molding time (vulcanization) in the manufacturing process The relatively long
manufacturing energy is large, and the degree of contamination of the mold is severe, so that the
mold maintenance cost such as the mold cleaning time is expensive.
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[0005]
Thermoplastic elastomers are one solution to the disadvantages of these vulcanized rubber
edges.
[0006]
Among these thermoplastic elastomers, so-called olefin elastomers composed of PP
(polypropylene) and EPDM (ethylene-propylene-gen terpolymer rubber) are excellent in
environmental properties and relatively thick, among others. High hardness products have heat
resistance enough to withstand in-vehicle use, but those with reduced thickness to cope with
high compliance or those with reduced hardness tend to be deformed, resulting in a drop in heat
resistance. Has the disadvantage of
[0007]
In the process of manufacturing a support system component for an electroacoustic transducer
using this thermoplastic elastomer, pellets → molded pellets into a predetermined shape by
injection molding → extruded sheet molding → molded pellets into a predetermined shape by
concavo-convex pattern → Molding to a predetermined shape by extrusion sheet molding →
vacuum molding is mainly used.
[0008]
The method of the present invention is excellent in terms of cost and freedom in product shape,
and in some cases, it may simultaneously bond with other parts (for example, the diaphragm
body, gasket, etc.) Since it is possible, it is a relatively excellent molding method.
However, if the residual stress and molding shrinkage at the time of molding are sufficiently
calculated, and production is performed without establishing the optimum mold structure and
molding conditions, problems of product variation such as deformation occur.
[0009]
Although it is difficult to use the method of product shape freedom and simultaneous molding
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and bonding with other parts (such as the diaphragm main body and the gasket etc.), the method
of molding is inexpensive and the manufacturing process is simple. And, since the product
variation is also small, as a result, inexpensive ones can be stably obtained.
However, since the sheet is produced by extrusion, it is difficult to produce a thin sheet (the level
which can be stably produced is up to about 0.30 mm) and flexibility can not be secured. It has
been difficult to meet the demand for lightweight, high compliance, which is increasing due to
the miniaturization of the
In addition, those with high hardness required and high hardness decreased heat resistance and
were unsuitable for use in vehicles.
[0010]
There is also a method of stretching and thinning, but the sheet produced by using this method
has a drawback that it is easily deformed since it has a large directionality.
[0011]
Further, sheet forming in the extrusion method takes a long time for color change due to the
mechanism of the machine, and it is expensive to cope with various color tones.
[0012]
[0012] In addition to the method of the method of the present invention, the edge molding die
becomes inexpensive, and the manufacturing process becomes simple.
In addition, since it becomes easy to develop into multi-pieces, it becomes a molding method of a
more superior support system component, but the defect is the same.
[0013]
The present invention has been proposed in view of the above, and the object of the present
invention is to make it thinner, to achieve weight reduction, to be able to secure flexibility and
heat resistance, and to be feared of deformation as well. It is another object of the present
invention to provide a support system component for an electroacoustic transducer which is easy
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to manufacture and can cope with various color tones and which is inexpensive.
[0014]
SUMMARY OF THE INVENTION In the present invention, a composition in which polypropylene
is blended with a styrenic thermoplastic elastomer in which hard segments are made of
polystyrene and soft segments are made of ethylene-propylene copolymer is molded into a
predetermined shape The configuration is to achieve the above purpose.
[0015]
Further, in this case, a sheet material obtained by forming the composition into a sheet by a
calender method is formed into a predetermined shape.
[0016]
Further, the sheet material is characterized by being formed by using a vacuum forming method.
[0017]
A support-system component formed by injection molding using a thermoplastic elastomer
consisting of conventional polypropylene and EPDM as a raw material is liable to be deformed
during molding, which causes a large problem in manufacturing stability.
In addition, a support system component obtained by forming this material into a sheet by
extrusion molding and shaping this sheet into a predetermined shape has little deformation at
the time of molding and can simplify the manufacturing process, but it is difficult to produce a
thin sheet and high compliance It was difficult to cope with it.
In addition, products that have been thin-walled by stretching or lowered in hardness to achieve
high compliance are prone to deformation and the like, and as a result, the heat resistance is
lowered, and heat resistance for in-vehicle use etc. is required It was unsuitable for the
application.
[0018]
On the other hand, in the present invention, high-compliance is achieved by molding a
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composition in which polypropylene is blended with a styrenic thermoplastic elastomer in which
the hard segment is polystyrene and the soft segment is ethylene-propylene copolymer. Support
components with excellent heat resistance.
[0019]
Further, by forming the composition into a sheet by using a calender system, a thin sheet with
less directionality can be prepared, and by forming the sheet into a predetermined shape, it is
light in weight, high in compliance and less in deformation. It is possible to provide a support
system component having high heat resistance.
In addition, since the calendar method can be relatively easily changed in color, it can meet
recent design requirements at low cost.
[0020]
Further, in the case where the sheet is formed into a predetermined shape using a vacuum
forming method, the mold becomes inexpensive, the manufacturing process can be simplified,
and a large number of pieces can be easily obtained. In addition, excellent productivity can be
added.
[0021]
EXAMPLES A method of manufacturing a support system component for an electroacoustic
transducer according to an embodiment of the present invention will be described below.
[0022]
In the present invention, polypropylene is blended with a thermoplastic polymer whose hard
segment is polystyrene and whose soft segment is ethylene / propylene polymer.
That is, as the thermoplastic polymer, 40 parts by weight of a styrene-based elastomer (made by
Kuraray Co., Ltd., trade name: Septon 4055), 20 parts by weight of polypropylene (trade name:
PH943B made by Japan Polyolefin), 40 parts by weight of paraffin oil, and other antioxidants
The ultraviolet absorber is placed in a mixer (not shown) of known configuration and heated and
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kneaded.
[0023]
Next, the kneaded product is sheeted by a calender method.
[0024]
As shown in FIG. 1, the periphery of the sheet material 1 in the form of a sheet is supported by a
support member 2 and heated in an infrared furnace (heated at a furnace temperature of 200 °
C. for 6.5 seconds).
In the figure, 3 is an infrared ray source.
The sheet material 1 is softened by the heating by the infrared ray source 3.
[0025]
The heated sheet material 1 is immediately placed on the vacuum forming mold 4 as shown in
FIG. 2 and attached to the vacuum forming mold 4 by vacuum suction as shown in FIG. Form the
sheet.
(This time, the vacuum strength of the vacuum pump: 200 mmHg, and the time for vacuuming:
10 seconds).
[0026]
Thereafter, as shown in FIG. 4, the molded product is cooled by forced air cooling with a fan (not
shown) in particular (10 seconds).
[0027]
Next, as shown in FIG. 5, air is fed from the vacuum drawing path to release the molded article
1A.
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[0028]
As shown in FIG. 6, the inner and outer peripheries of the molded article 1A are trimmed to
predetermined dimensions to produce, for example, an edge member 5.
[0029]
Then, as shown in FIG. 7, the outer peripheral portion of the diaphragm body 6 is bonded to the
above-mentioned speaker edge material 5 to obtain a speaker diaphragm.
[0030]
The features of the product of the present invention thus produced are as follows.
[0031]
The hard segment is composed of polystyrene and the soft segment is an ethylene-propylene
copolymer, as compared with an edge material obtained by extruding a conventional olefin
elastomer (a thermoplastic elastomer having EPDM as a soft segment and polypropylene as a
hard segment). In the product of the present invention, which is made of a composition in which
polypropylene is blended with a styrenic thermoplastic elastomer comprising the above, and
which is sheeted and which uses a vacuum forming method, it is thinner (as a result, lighter) and
flexible. Therefore, when it uses for a speaker, fo can be made low.
Incidentally, the conventional product (an edge material made by extruding a thermoplastic
elastomer containing EPDM as a soft segment and polypropylene as a hard segment) has a limit
of 0.3 mm, but the product of the present invention has a thin thickness of 0.1 mm. Sheet was
produced.
[0032]
Furthermore, since this edge material 5 is also excellent in heat resistance and has better heat
resistance than conventional products as shown in Table 1 below, it is stable even under severe
temperature conditions such as a car etc. Performance can be obtained over a long period of
time.
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Table 1
[0033]
Further, this edge member 5 has less temperature dependency than the conventional product,
and when used for a speaker, as shown in Table 2 below, there is little change with respect to the
temperature of the speaker's fo and a wide temperature Stable acoustic performance is obtained
in the region.
Table 2
[0034]
FIG. 8 shows the temperature dependency of fo of the speaker of the present invention and that
of the conventional product.
[0035]
In the above embodiment, although an example of preparation of the edge member 5 as a
support system component has been described, other support system components, that is,
dampers can be prepared in substantially the same manner, and dampers having similar physical
properties can be manufactured. You can get it.
[0036]
As described above, according to the present invention, a composition in which polypropylene is
blended with a styrenic thermoplastic elastomer in which the hard segment is composed of
polystyrene and the soft segment is composed of an ethylene-propylene copolymer has a
predetermined shape. An excellent electroacoustic transducer support system component that is
thin-walled and thus flexible and has high bending fatigue resistance, is excellent in weather
resistance, heat resistance and waterproofness, and is also compatible with environmental
problems. Can be provided.
[0037]
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Furthermore, by making the composition into a sheet using a calendar system, it is possible to
easily make a thin sheet (can be up to 0.1 mm), and the demand has been increased by the recent
miniaturization of speakers. Lightweight and compatible with high compliance.
In addition, since the directionality is small, deformation is less likely to occur.
In addition, since color change is easier compared to extrusion sheet forming, various color tones
can be handled at low cost.
[0038]
Further, by molding the above-mentioned sheet material using a vacuum forming method, it is
possible to reduce the mold cost and the manufacturing cost.
[0039]
Further, the sheet material obtained in this configuration is free of coloring, and since it uses a
calendar-type sheeting method, it can flexibly cope with a small lot of color-matched varieties,
thus meeting the demand for recent designs It is also possible to respond quickly and at a low
cost.
[0040]
Brief description of the drawings
[0041]
1 is an explanatory view of one step of the manufacturing process of a support system
component for an electroacoustic transducer of one embodiment according to the present
invention.
[0042]
2 is an explanatory view of the next manufacturing step of the same.
[0043]
FIG. 3 is an explanatory view of the next manufacturing process.
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[0044]
FIG. 4 is an explanatory view of the next manufacturing process.
[0045]
FIG. 5 is an explanatory view of the next manufacturing process.
[0046]
6 is an explanatory view of the manufacturing process of the final stage of FIG.
[0047]
7 is a schematic explanatory view of a state in which the support portion made according to the
present invention is incorporated into the diaphragm of the speaker.
[0048]
8 shows the temperature dependency of the speaker fo of the present invention and the
conventional product.
[0049]
Explanation of sign
[0050]
Reference Signs List 1 sheet material 2 support part 3 infrared ray source 4 vacuum forming
mold 5 edge member 6 diaphragm body
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