JP4019369B2 - Method for producing thermoplastic acoustic plate - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention provides a disk-shaped disc including a vibration plate and a damper that form a predetermined region of the plate surface in a predetermined three-dimensional shape while maintaining the central portion of the plate surface at the thickness of the film itself and forming the peripheral portion in a thin film shape. The present invention relates to a method for producing a thermoplastic resin acoustic board, in which an acoustic board is molded from a single thermoplastic resin film by a hot press.
[0002]
[Prior art]
In general, exemplifying the case of manufacturing a diaphragm incorporated in an acoustic device such as a speaker or a mobile phone, the central portion of the plate surface is kept at the thickness of the film itself and the peripheral portion is formed in a thin film shape. High-pitched sound reproduction is obtained from the relatively thick film thickness, and on the other hand, the diaphragm having an arbitrary minimum resonance frequency (f ₀ ) is obtained by changing the thickness using the peripheral portion as an edge portion having a thin film thickness. It is known that it can be obtained as
[0003]
Conventionally, when the diaphragm is manufactured from a resin film, a central portion and a peripheral portion made of resin films having different thicknesses are bonded to each other at inner and outer peripheral edges. However, since the bonding of the resin film is extremely laborious and costly, it has been attempted to produce a diaphragm by applying press molding or vacuum molding from a single thermoplastic resin film.
[0004]
As an example of the manufacturing method, press forming has been proposed (Patent Document 1). This press molding is disclosed to be performed using a molding die having a cylindrical elastic body that sandwiches a peripheral portion of a thermoplastic resin film from above and below, and male and female molds that move up and down inside the elastic body. Yes.
[0005]
First, the thermoplastic resin film is heated with a heater. Next, the peripheral part of the thermoplastic resin film is sandwiched from above and below by a cylindrical elastic body that can spread in a skirt shape, and the entire film is held horizontally, and by male and female molds that move up and down inside the elastic body. A central portion of the thermoplastic resin film is formed into a predetermined three-dimensional shape. After that, it is disclosed that high-pressure air is sent inward of the elastic body from the air introduction hole of each mold, the elastic body is spread in a skirt shape, and the peripheral portion of the thermoplastic film is stretched to form a thin portion. Has been.
[0006]
In the manufacturing method of the diaphragm, since the thermoplastic resin film is heated and then set on the mold side, it takes time until this setting, and from the press molding of the central part to the stretching of the peripheral part. If time is required, there is a possibility that the heating temperature is lowered and the peripheral portion cannot be stretched as desired. Furthermore, it is difficult to clearly define the boundary of thickness by stretching the thermoplastic resin film by expanding the elastic body with high-pressure air, and if the central part is not firmly sandwiched by the mold, the peripheral part is pulled. There is also a possibility that the stress by acts on the central part.
[0007]
As another example, it has been proposed to apply vacuum forming (Patent Document 2). The vacuum molding is a vacuum molding in which the mold surface is divided into three parts, a central part molding part, a stretched part molding part, and an outer peripheral part molding part, and vacuum suction holes are provided in the mold surface to communicate with each of the partitioned molding parts. It is disclosed to use a mold.
[0008]
The vacuum molding is performed by heat-treating the thermoplastic resin film with a heater opposite to the vacuum mold, and then aligning the vacuum mold with the heater to hold the thermoplastic resin film horizontally, Pressure is applied to the central part molding portion to press the central portion of the thermoplastic resin film against the mold surface. Next, a vacuum pressure is applied to the outer peripheral portion molding portion so that the outer peripheral portion is pressed against the mold surface to create a state in which the vacuum pressure can be applied to the stretched partial molding portion. Finally, it is disclosed that a vacuum pressure is applied to the stretched part forming part to form a peripheral stretched part.
[0009]
In the vacuum molding, if the mold surface of the stretched part molding part defined by the vacuum suction holes has a small degree of elevation, a thin stretched part is formed until the lowest resonance frequency (f ₀ ) can be exhibited. Can not. On the other hand, if the mold surface of the stretched part molding part has a large degree of bulging, the stretched part exhibits a curved rib shape, and conversely, since it gives rigidity, the frequency characteristics do not change. There is a risk of becoming.
[0010]
[Patent Document 1]
JP 59-62296 A [Patent Document 2]
Japanese Patent Laid-Open No. 61-95700
[Problems to be solved by the invention]
According to the present invention, the heating state of the thermoplastic resin film can be accurately maintained until the peripheral portion is stretched to stretch the peripheral portion as desired, the boundary of the thickness difference can be clearly defined, and at least the outer peripheral edge portion can be flattened. An object of the present invention is to provide a method for manufacturing a thermoplastic acoustic plate capable of reliably changing the lowest resonance frequency (f ₀ ) because it can be formed as a thin-film edge portion.
[0012]
[Means for Solving the Problems]
In the method for manufacturing a thermoplastic resin acoustic plate according to claim 1 of the present invention, the central portion of the plate surface is maintained at the thickness of the thermoplastic resin film itself, and the peripheral portion of the plate surface is formed in a thin film shape, and the plate surface A diaphragm that forms a predetermined region of a predetermined three-dimensional shape, a disk-shaped acoustic plate including a damper is heat-molded from a single thermoplastic resin film with a press die,
As another press mold prior to shaping a predetermined area of the plate surface into a three-dimensional shape, a concave mold having a mold surface with an inner peripheral surface having a predetermined rise and an inner bottom surface continuing from the inner peripheral surface is provided. Provided with a convex mold with a built-in heater having an end surface of a predetermined width extending from the opening to the outer periphery and an outer peripheral surface that can be fitted into a concave mold while maintaining a gap of a predetermined width;
After placing a single thermoplastic resin film having a surplus area wider than at least the inner bottom surface of the concave mold on the concave mold surface, the convex mold maintained in a heated state is inserted into the concave mold and moved. Due to the insertion movement of the convex mold, the end face of the convex mold is brought into contact with the required surface of the thermoplastic resin film to heat and soften the required surface, and the excess part of the thermoplastic resin film is formed into the concave inner peripheral surface and the convex mold. The required surface including the excess portion of the thermoplastic resin film is press-fitted into the concave mold with the convex end face while the tensile force is applied to the outer peripheral surface of the thermoplastic resin film. Finally, the required surface of the thermoplastic resin film is pressed against the inner bottom surface of the concave mold with the convex end face, and the central portion of the plate surface is maintained at the thickness of the film itself with the convex opening, and the peripheral portion of the plate surface Is formed into a thin film with a convex end face .
[0013]
In the method of manufacturing a thermoplastic resin acoustic plate according to claim 2 of the present invention, after obtaining the thermoplastic resin film in which the central portion of the plate surface is maintained at the thickness of the film itself and the peripheral portion is formed in a thin film shape, With this press mold, the rippled undulations are press-molded into the central portion of the film itself, and finally, the surplus portion of the thermoplastic resin film is cut off to produce a diaphragm.
[0014]
In the method for producing a thermoplastic resin acoustic plate according to claim 3 of the present invention, after obtaining the thermoplastic resin film in which the central portion of the plate surface is kept at the thickness of the film itself and the peripheral portion is formed in a thin film shape, With this press mold, the rippled undulations are press-molded in the peripheral part formed into a thin film shape, and finally the excess part of the thermoplastic resin film is cut off to produce a damper.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to the accompanying drawings, the illustrated embodiment is applied to manufacturing a diaphragm to be incorporated in an audio device such as a speaker or a mobile phone. This diaphragm is formed from a thermoplastic resin film such as polycarbonate or polyetherimide (PEI). In particular, polyetherimide is preferred because it is inexpensive and easy to stretch.
[0016]
The diaphragm is obtained by hot pressing a single thermoplastic resin film. Further, as shown in FIGS. 1 and 2, the central portion a (see the hatched portion in FIG. 1) of the plate surface is kept at the thickness t _{1 of the} film itself, and the peripheral portion b (see the white portion in FIG. 1) the thickness t ₂ so as to form a thin film, resulting from the shaping cone-shaped three dimensional c the central portion c as a vibrating unit.
[0017]
In manufacturing the diaphragm, the first press mold that forms the peripheral portion b in a thin film and the second press mold that is formed into a three-dimensional shape with the central portion a as the vibration portion are individually used. It is set to press-mold. Further, prior to forming the central portion a of the plate surface into the three-dimensional shape c, first, the peripheral portion b of the plate surface is set to be formed in a thin film shape. In addition, since a general purpose thing is used as a 2nd press-molding die, illustration is abbreviate | omitted.
[0018]
As shown in FIG. 2, the first press mold is a concave mold 1 (shown as “lower mold” or “female mold” in the drawing) and a convex mold 2 (shown as “upper mold” in the drawing). It appears as “male”.) The concave mold 1 is assembled from a perfectly circular ring 10 and a lower base 11 on which the ring 10 is installed on the plate surface. In the concave mold 1, the inner diameter side of the ring 10 has a rise corresponding to the plate thickness. A mold surface is formed from the inner peripheral surface 12 and an inner bottom surface 13 formed by a plate surface of the lower base 11 surrounded by the inner peripheral surface 12 of the ring 10.
[0019]
The convex mold 2 is formed integrally with a lower cylindrical portion 20 as a main body and an upper projecting ring portion 21. In this configuration, a mold surface is formed from an end surface 23 having a predetermined width extending from the opening 22 provided at the center of the cylindrical portion 20 to the outer periphery and the outer peripheral surface 24. In the cylindrical portion 20, the width surface of the end surface 23 becomes a surface that presses the outer peripheral portion of the diaphragm into a thin film shape, and the outer peripheral surface 24 can be fitted into the mold of the concave mold 10 while maintaining a gap g of a predetermined width. It becomes a serious aspect.
[0020]
The convex mold 2 is configured as a heater built-in type from four cartridge heaters 25 provided inside the cylindrical portion 20 as shown in FIG. In the convex mold 2, a through hole 26 extending from the outer peripheral surface of the overhang ring portion 21 to the opening 22 is provided, and a temperature sensor for managing the heating temperature by the cartridge heater 25 is attached. A wiring groove 27 of the cartridge heater 25 is provided in the overhang ring portion 21. The convex mold 2 is installed downward from the plate surface of the upper base (not shown), and is provided so that the press can be lowered or retreated by a pressure drive cylinder.
[0021]
In the first press mold described above, the entire mold surface of the concave mold 1 and the convex mold 2 or at least the end surface 23 of the convex mold 2 and the inner bottom surface 13 of the concave mold 1 facing the end surface 23 of the convex mold 2 are flat mirror surfaces. It is formed as. Further, in order to enhance the tensile action of the thermoplastic resin film F to be described later, the inner peripheral surface 12 of the concave mold 1 and the outer peripheral surface 24 of the convex mold 2 can be formed on a rough surface as necessary.
[0022]
Using the first press mold, first, a single thermoplastic resin film F is placed on the mold surface of the concave mold 1 as shown in FIG. As the thermoplastic resin film F, a film cut into an area having an excess portion f ₁ wider than at least the inner bottom surface 13 of the concave mold 1 is used. Moreover, it is good to use what was cut | judged in the strip | belt shape so that it can feed continuously with respect to one press-molding die, and two or more can be taken from one sheet.
[0023]
After the thermoplastic resin film F is placed on the mold surface of the concave mold 1, the cylindrical portion 20 of the convex mold 2 kept in a heated state is moved down so as to be fitted into the concave mold 1. With the downward movement of the convex mold 2, as shown in FIG. 6, the end surface 23 extending from the opening 22 to the outer peripheral surface 24 of the convex mold 2 is changed to the required surface f ₂ of the thermoplastic resin film F, that is, a thin film. Heat softening is started by contacting the surface corresponding to the outer peripheral portion to be formed.
[0024]
By further fitting the cylindrical portion 20 inside the concave 1 while maintaining the convex 2 in a heated state, concave required surface f ₂ containing excess portion f ₁ of the thermoplastic resin film F as shown in Figure 7 The inner peripheral surface 12 of 1 and the outer peripheral surface 24 of the convex mold 2 are sandwiched between the gaps g to be drawn in and inserted. At this time, since the excess portion f ₁ and the mold surface of the thermoplastic resin film F is brought into sliding contact, the tensile force with acts on the thermoplastic resin film F, the required surface f ₂ of the thermoplastic resin film F is heated Therefore, the required surface required surface f ₂ starts to stretch.
[0025]
By press-fitting of the thermoplastic resin film F, finally, since the pressure contact with the thermoplastic resin film inner bottom surface 13 of the concave 1 the required surface f ₂ at the end face 23 of the convex second F as shown in Figure 8, the plate The central portion a of the surface (see FIG. 1) is maintained at the thickness t ₁ (see FIG. 2) of the film itself with the opening 22 of the convex mold 2, and the peripheral portion b of the thin film thickness t ₂ is formed into a thin film like the end surface of the convex mold 2 23, and the boundary between the central portion a of the plate surface and the peripheral portion b of the plate surface is clearly attached.
[0026]
The thermoplastic resin film formed into a thin film by stretching is removed from the first press mold as shown in FIG. 9, and the cone-shaped undulation c (see FIG. 1) is removed by the second press mold. Is press-molded into the central portion a kept at the thickness of At this time, if necessary, in order to reinforce the thin film-shaped peripheral portion b so as not to affect the lowest resonance frequency (f ₀ ), a cone-shaped undulation d (see FIG. 1) can be formed.
[0027]
The thermoplastic resin film F of removal from the second press mold, finally, punch the excess portion f ₁ of the thermoplastic resin film F as shown in Figure 10, by cut processing with a press cutter according to the die Manufactured as a diaphragm. In this diaphragm, since at least the outer peripheral edge portion can be formed as a flat thin film edge portion, the minimum resonance frequency (f ₀ ) can be reliably changed.
[0028]
Regarding the specific condition setting, a case where a small speaker diaphragm having a diameter of about 39 mm is manufactured from polyetherimide having a film thickness of 100 μm is illustrated. The inner diameter of the concave shape is 50 mmφ, the inner diameter of the concave shape is 10 mm, Since the outer diameter of the convex mold is 49 mmφ, the diameter of the central hole is 29 mmφ, the heating temperature of the convex mold is 230 ° C., the pressing force of the convex mold is 5 kg, and the pressing time by the convex mold is about 3 seconds. The peripheral portion can be formed as a thin film having a thickness of about 60 μ while keeping the film thickness at 100 μ.
[0029]
Although the above-described embodiment has been described based on the case of manufacturing a diaphragm, as shown in FIGS. 11 and 12, the central portion a ′ of the plate surface is kept at the thickness of the film itself, and the peripheral portion b ′ is formed into a thin film. Furthermore, it can also be applied to manufacture a damper by press-molding a cone-shaped undulation c ′ into a peripheral portion b ′ formed into a thin film. Further, the three-dimensional shape is not limited to the cone shape, and can be applied to the manufacture of products having a dome shape or a horn shape.
[0030]
【The invention's effect】
As described above, according to the method for manufacturing a thermoplastic resin acoustic plate according to the present invention, prior to forming a predetermined area of the plate surface into a three-dimensional shape, a single thermoplastic resin film is placed on the concave mold surface. After the mounting, the convex end face kept in a heated state is brought into contact with the required surface of the thermoplastic resin film to heat and soften the required surface, and the excess portion of the thermoplastic resin film is removed from the concave inner periphery. The required surface including the surplus portion of the thermoplastic resin film is press-fitted into the concave mold at the convex end face while the tensile force acts on the thermoplastic resin film by being sandwiched between the surface and the convex outer peripheral surface. The required surface of the thermoplastic resin film is pressed against the concave inner bottom surface at the convex end face, and the central portion of the plate surface is kept at the thickness of the film itself with a convex opening, and the peripheral portion of the plate surface is made into a thin film Since it is formed with a convex end face, the heating state of the thermoplastic resin film can be accurately determined. With Stretch ability peripheral portion as desired, clearly bounded thickness difference, also, it is possible to form at least the outer peripheral edge portion as a flat thin film of the edge portion, the lowest resonance frequency (f ₀₎ surely I It is obtained as a thermoplastic resin acoustic board that can be changed into
[Brief description of the drawings]
FIG. 1 is a plan view showing a diaphragm obtained by a method for producing a thermoplastic resin acoustic plate according to the present invention.
FIG. 2 is a side sectional view showing the diaphragm of FIG.
FIG. 3 is a side sectional view showing a press die for carrying out the method for producing a thermoplastic resin acoustic plate according to the present invention.
4 is a plan view showing a convex mold in the press mold of FIG. 3. FIG.
5 is an explanatory view showing a setting process of a thermoplastic resin film in the press die of FIG. 3. FIG.
6 is an explanatory view showing a downward movement start process of the convex mold following the press mold of FIG. 5; FIG.
7 is an explanatory view showing a state in which a convex mold is being inserted following the press mold of FIG. 6; FIG.
FIG. 8 is an explanatory view showing a pressed state of a thermoplastic resin film by a convex mold following the press mold of FIG. 7;
9 is an explanatory view showing a process of removing a thermoplastic resin film subsequent to the press mold of FIG. 8. FIG.
FIG. 10 is an explanatory view showing a cutting step of cutting an excess portion from a thermoplastic resin film after press molding.
FIG. 11 is a plan view showing a damper obtained by the method for producing a thermoplastic resin acoustic plate according to the present invention.
12 is a side cross-sectional view showing the damper of FIG. 11. FIG.
[Explanation of symbols]
F Thermoplastic resin film f ₁ Excess part of film f ₂ Required surface a of film a Central part b to keep the film thickness Thin peripheral part c Three-dimensional shaped part 1 Concave 12 Concave inner peripheral surface 13 Concave inner bottom 2 Convex 22 Convex opening 23 Convex end surface 24 Convex outer peripheral surface

Claims (3)

A disc-shaped acoustic plate including a vibration plate and a damper that form a predetermined three-dimensional shape on the plate surface while keeping the central portion of the plate surface at the thickness of the film itself and forming the peripheral portion in a thin film shape. In the method for producing a thermoplastic resin acoustic board, which is molded from a sheet of thermoplastic resin film with a hot press,
As another press mold prior to shaping the predetermined area of the plate surface into a three-dimensional shape, a concave mold having an inner peripheral surface having a predetermined rising and an inner bottom surface continuing from the inner peripheral surface as a mold surface is provided. A heater-incorporated convex mold having an end face of a predetermined width extending from the opening of the hole to the outer periphery and an outer peripheral surface capable of being fitted into a concave mold while maintaining a gap of a predetermined width;
After placing a single thermoplastic resin film having a surplus area wider than at least the inner bottom surface of the concave mold on the concave mold surface, the convex mold maintained in a heated state is inserted into the concave mold and moved. Due to the insertion movement of the convex mold, the end face of the convex mold is brought into contact with the required surface of the thermoplastic resin film to heat and soften the required surface, and the excess part of the thermoplastic resin film is formed into the concave inner peripheral surface and the convex mold. The required surface including the excess portion of the thermoplastic resin film is press-fitted into the concave mold with the convex end face while the tensile force is applied to the outer peripheral surface of the thermoplastic resin film. Finally, the required surface of the thermoplastic resin film is pressed against the inner bottom surface of the concave mold with the convex end face, and the central portion of the plate surface is maintained at the thickness of the film itself with the convex opening, and the peripheral portion of the plate surface Is formed in a thin film with a convex end face Method for producing a thermoplastic resin acoustic plate characterized. After obtaining the thermoplastic resin film in which the central part of the plate surface is kept at the thickness of the film itself and the peripheral part is formed in a thin film shape, the rippled undulations are kept at the thickness of the film itself by another press die. 2. The method for manufacturing a thermoplastic resin acoustic plate according to claim 1, wherein the diaphragm is manufactured by press-molding at a central portion and finally cutting off an excess portion of the thermoplastic resin film. After obtaining the thermoplastic resin film in which the central part of the plate surface is kept in the thickness of the film itself and the peripheral part is formed into a thin film, the peripheral part in which rippled undulations are formed into a thin film by another press die The method for producing a thermoplastic resin acoustic plate according to claim 1, wherein the damper is produced by press-molding, and finally, a surplus portion of the thermoplastic resin film is cut off to produce a damper.

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