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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
financial decisions, should not be based on machine-translation output.
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a
method of forming a diaphragm for a small size sound generator. More specifically, the present
invention relates to a method of mass-producing a complete product of a diaphragm for a small
sounding body from a film of a polymeric material.
2. Description of the Related Art Ultra-compact electrodynamic speakers are generally used for
small or portable electronic devices such as portable telephones. The method of manufacturing
the diaphragm usually uses a film of a polymeric material as a material, which has appropriate
flexibility and rigidity (preferably having flexibility in axial translation and rigidity against
deformation in other directions). In order to hold it, a ring-like or radial concavo-convex shape is
given by a heat press molding method, and then the outer shape of a disc-like molded article of
concavo-convex shape is punched out from the film material to obtain a finished product.
Heretofore, the thermal press forming and the punching have been separate steps, both of which
are manual. A conventional manufacturing method will be described with reference to FIG.
FIG. 4 is a side view (partially sectional view) of an apparatus used for manufacturing a
conventional diaphragm, in which (a) shows a heat press-forming machine and (b) shows a
manual press for removing outlines. First, in (a), the base 42, the support 43, and the upper plate
44 constitute a machine frame. The upper plate 44 holds a heater 49 for heating the mold, the
base 42 holds a lower die 50, and the support 43 holds a nozzle 51 for cooling air. A shaft 46
vertically driven by an air cylinder 45 slidably penetrates the upper plate 44, and holds a plate
47 having a mold 48 mounted at its lower end.
The flat material film 41 is cut to an appropriate size so as to cover one product, and the
operator manually inserts and sets this in the gap between the mold 48 and the lower mold 50 of
the heat press molding machine. . The shaft 46 is at the upper end, the plate 47 is in contact with
the lower surface of the heater 49, and the mold 48 is heated by the heater 49 via the plate 47 to
a temperature that softens the material film 41. Next, when the air cylinder 45 is driven, the
mold 48 descends, and the raw material film 41 is strongly held together with the lower mold 50,
and the raw material film 41 is transferred and deformed by the uneven shape of the surface of
the mold 48.
The lower mold 50 may be a metal mold having an uneven surface opposite to that of the mold
48, or may be a block of silicone rubber. In the latter case, the silicone rubber material deforms
in accordance with the mold and, at the same time, the material film 41 is compressed from
below by the repulsive force of pressure reduction. When molding is completed, cold air is blown
out from the cooling nozzle 51 to rapidly cool the mold 48 and make it easy to remove the semifinished product of the diaphragm from the mold 48.
The manual pressing machine shown in FIG. 4 (b) is an apparatus for forming a diaphragm into a
finished product by rounding it out to finish the outer shape of a material film (semi-finished
product) on which the concavo-convex shape of the diaphragm is formed by the abovementioned heat press forming machine. It is. A die 54 is attached to the lower part of the Cshaped frame 52, and a punch 55 is attached to the lower end of the shaft 56 which can slide the
upper part in the vertical direction. 57 is a handle, 58 is a restoring spring. The operator
manually sets the molded but attached semi-finished product 53 on the peripheral edge on the
cylindrical die 54 and depresses the handle 57, and the cylindrical punch 55 punches the central
portion into a circle, which is a product It becomes a completed diaphragm. Products and scraps
(waste materials) are collected in separate containers.
The above-mentioned prior art has the following problems. (1) It takes time for heat press
molding, and it takes 20 to 60 seconds depending on the material of the material, which hinders
cost reduction. (2) It is difficult to automate the entire process consistently because the heat
press molding and the outline removal are completely separated. (3) The shape accuracy of the
product is not always satisfactory. For example, even if the working temperature and time are
managed, the quality can not be sufficiently uniform. Since this is a manual operation one by one,
it is considered that the processing conditions are not stable.
SUMMARY OF THE INVENTION The object of the present invention is to solve the above
problems and provide a method of forming a diaphragm for a small sounding body capable of
achieving consistent automation and significantly reducing the forming time and obtaining
extremely accurate and stable shape quality. It is to be.
SUMMARY OF THE INVENTION In order to achieve the above object, the method for forming a
diaphragm for a small size sound generator of the present invention has the following features.
(1) While intermittently feeding a film of a band-like polymeric material as a material of a
diaphragm having a concavo-convex shape with a predetermined stroke intermittently, the film
from a hole, a recess or a protrusion for positioning with the stroke Forming a concavo-convex
shape for the diaphragm sequentially by pressing a heated mold to a place having a
predetermined positional relationship with the positioning means of the film. And a third step of
punching out the outer shape of the diaphragm with the film having the concavo-convex shape
formed thereon as a position reference.
The method for forming a diaphragm for a small size sound generator according to the present
invention may further include at least one of the following features. (2) The film of the material is
wound around a reel and supplied, and the band-like remaining material after the diaphragm is
removed is wound around a reel and collected.
(3) The first and second steps are performed at a first station, and the third step is performed at
another station.
(4) In the second step, the heated mold is brought close to one side of the film at the first station,
and a high pressure gas is applied to the other side to crimp the sheet to the surface of the mold.
The film is thermally deformed by molding to form the film into the concavo-convex shape of the
diaphragm, and the protrusion is simultaneously formed on the film surface using a part of the
(5) The first step of forming the projection is performed simultaneously with the second step of
forming the uneven shape of the diaphragm in the first station.
an example of the entire apparatus according to the present invention, in which a complete
diaphragm as a product is obtained by continuously processing a material film supplied as a
band material. (B) is a top view which shows the raw material film (semi-finished product) of the
thermoformed state.
A reference numeral 11 denotes a supply side reel in which a long strip of material film is wound,
and 12 denotes a drawn material film.
13 is a thermoforming machine and constitutes the first station.
The forming method will be described in detail later with reference to FIG. The raw material film
14 which has become a semi-finished product when leaving the molding machine 13 has a shape
as shown in FIG. 1 (b). 14a is a formed uneven shape, and 14b is a pair of positioning means
such as a small hole, a small recess or a small protrusion.
The positioning means 14b enlarges the area of the mold (26 in FIG. 2) of the thermoforming
machine 13, and a diaphragm is provided by providing a pair of concave or convex portions (not
shown) in a part thereof. It can be easily molded while maintaining a predetermined accurate
positional relationship with the concave-convex shaped portion for use. The reference numeral
15 designates a machine for removing molded articles and constitutes a second station. Although
the specific structure is not shown, it is as follows. First, the raw material film 14 which has
become a semi-finished product with a gap between the punching punch and the die is fed by
about one pitch (equal to the forming interval of the diaphragm). The forming operation of the
thermoforming machine 13 and the punching operation of the outline removing machine 15 are
performed in synchronization with each other.
The outline removing machine 15 is provided with a pin or small hole for positioning, and
punching of the outline by a punch and a die is performed in a state where the hole, recess or
protrusion of the positioning means 14b is lightly fitted and positioned. Although the completed
diaphragm (product) which has been punched may be dropped to the tray and recovered in the
molded product shape removing machine 15, in this example, the molded product shaped shape
removing machine is lightly fitted to the removed original hole. 15. From 15 (film with finished
product 16), the product is stored in a product pallet (not shown) in a product pallet storage
machine 17 constituting a third station. The waste material 15 leaving the product pallet storage
machine 17 is wound around a take-up reel 19 and collected. The arrangement of the forming
machine and the punching machine in series to build up a consistent processing line which
requires almost no involvement of the worker until the storage of the finished product can be
achieved by the above explanation and the fact that it is more compact than the metal strip It can
be realized by applying various existing techniques for forming
Fig.2 (a) is sectional drawing of the thermoforming machine used at the thermoforming process
of the formation method of the diaphragm which is an example of embodiment of this invention,
(b) is sectional drawing which shows the formation condition of a raw material. The
thermoforming machine has two frames, an upper frame 22 and a lower frame 25 as basic
structures. These frames are disposed at the upper and lower sides of the raw material film 20
and have an opening / closing mechanism which strongly sandwiches the raw material film 20
from both the upper and lower sides while being accurately positioned, or slightly opens a gap to
allow passage of the raw material film 20. (The opening and closing mechanism is omitted
because it is not a particularly difficult structure). The upper frame 22 is substantially hollow,
and is provided with a seal ring 23 of a heat-resistant elastic material, for example, of a silicon
type, for airtightly pressing the material film 20, and a high pressure air inlet 24. The lower
frame 25 holds a die 26 for forming the diaphragm close to the lower surface of the crimped and
held raw material film 20 and heating means 27 comprising a heater for heating the die 26, a
molten solder tank or the like, Further, a cooling air discharge port 28 for cooling the mold 26 is
The forming operation will be described sequentially. First, the flat portion of the continuous
material film 20 is inserted into the gap between the upper frame 22 and the lower frame 25.
Next, the upper frame 22 and the lower frame 25 approach each other, and the raw material film
20 is pressure-bonded and air pressurized from the high-pressure air inlet 24 is blown in, and
the raw material film 20 bends downward and contacts the heated mold 26. Soften. The
softening is expanded from the central portion of the material film 20 and finally comes into
contact with the entire surface of the mold 26, and the molding is completed. This state is shown
in FIG. 2 (b). 21 is a semi-finished product of a diaphragm. In this molding machine, the working
time was reduced to about 10 to 30 seconds, which is almost a half of the conventional one, and
significant cost reduction was achieved.
If air is trapped between the material film 20 and the die 26 in the process of forming the raw
material film 20, the shape accuracy of the product is impaired. It is a structure that escapes to
the back of the Since the small holes are small, they are not shown in FIGS. 2 (a) and 2 (b), but
are shown in detail in FIG. The elements other than the mold are not shown. Next, the cooling air
is blown out from the cooling air discharge port 28 to lower the temperature of the mold 26
below the softening point of the material film 20. Subsequently, when the gap between the upper
frame 22 and the lower frame 25 is opened, the material film 20 which has become a semifinished product easily leaves the mold surface and is fed until the next flat portion is just above
the mold 16.
FIG. 3 shows the detailed shape of the embodiment of the mold 26 of the present invention
giving the concavo-convex shape of the diaphragm, wherein (a) is a plan view, (b) is a sectional
view and (c) is a partially enlarged sectional view It is. The mold 26 is substantially circular, and
the ring-shaped deep recess 31 near the center is a portion forming a ring-shaped earth
embankment for bonding the cylindrical voice coil to the diaphragm, and a plurality of ringshaped curved portions close to the outer periphery The portion 32 forms a shape that gives the
diaphragm flexibility in axial movement, and the inner radial curved portion 33 has a large
number of radiuses and slopes (only a portion is shown, but in this example, each direction is 10
° (36 different) in the shape of a willow-shaped uneven portion, which is a portion that imparts
a shape that mainly increases the rigidity to the vibrating portion of the diaphragm.
Denoted at 34 are exhaust holes, which are provided several or more over the entire surface of
the mold so as to penetrate the upper and lower surfaces of the mold. The diameter of the holes
should be small enough to make the shape of the holes less visible in the product. However, as
shown in FIG. 3C, the opening diameter of the pilot hole opened from the lower surface side of
the mold 26 may be large. In the experimental example, the upper surface side in contact with
the material film 20 had a diameter of 0.025 mm, and the lower surface side had a diameter of 1
mm. The position of the hole is provided at the top of the convex portion of the mold or at the
bottom of the concave portion, and it is considered that it is desirable and effective in terms of
mold processing to avoid a steep slope. In this example, the exhaust holes 34 are provided at
intervals of 90 ° on several circumferences which make the distance from the central axis of the
mold 26 in particular.
Although one example of the embodiment of the present invention has been described above, the
present invention is not limited to only the above-described embodiment. For example, only the
positioning means may be processed at the first station, and the diaphragm may be formed with
the processed positioning means as a position reference at the next station. In addition, the
outline removal and product pallet storage may be performed at one station. With regard to the
forming process, the material of the polymer film material, the heating of the mold, the structure
of the cooling means, the type of gas to be pressurized, the pressure, the temperature, or the
position, shape, depth, etc. It is easy to change the experimental conditions variously and set the
optimum conditions as basic conditions such as the required acoustic characteristics. The
diameter and the number of exhaust holes are also optional. Moreover, the processing method of
this diaphragm can be applied to a diaphragm for an earphone or a microphone as well as for a
small speaker. Moreover, even if it does not necessarily perform a consistent process by a band
material, the improvement effect of a product quality and shortening of processing time can be
exhibited, if only the forming method by gas pressurization is implemented.
According to the present invention, since the material is formed into a band shape and the
forming machine and the outline removing machine are arranged in series to perform continuous
processing, the condition is constant since the operator does not intervene in the process. Highly
stable product quality was obtained. In addition, consistent automated processing has become
possible, and significant cost reduction effects have been achieved. Furthermore, if the pressure
of the gas is used in the thermal forming of the diaphragm, and the air between the material and
the mold is not released and confined, the adhesion between the material and the mold is
significantly improved during shaping. Thus, the effect of extremely excellent and stable shape
accuracy was obtained.
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