JPH06133392A - Manufacture of diaphragm for speaker - Google Patents

Abstract

PURPOSE:To provide the manufacture of the diaphragm for speaker with high degree of freedom of a shaped form and an excellent property. CONSTITUTION:A metallic die 1 in which the thickness of a cavity 13 is changed partially and continuously is employed and the thickness of the diaphragm is changed by applying hot press forming to an unwoven cloth including a prescribed quantity of thermosetting resin fibers at a temperature higher than the softening-temperature of the thermosetting resin fibers and lower than the melting temperature.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a diaphragm for a speaker.

[0002]

2. Description of the Related Art Generally, it is said that the physical properties of a diaphragm for a speaker are light weight, high elastic modulus, large internal loss, and the like.

[0003] By the way, the paper-made diaphragm, which has been widely used from the past, by the papermaking of wood pulp has the physical properties that it has a large degree of freedom in its molding shape, is relatively lightweight, and has a large internal loss. However, on the other hand, since the elastic modulus is remarkably small and the moisture resistance is poor, many improved products have been proposed.

[0004]

For example, there is a diaphragm produced by molding a high-elasticity fiber woven fabric prepreg such as carbon fiber. Although this diaphragm can obtain a large elastic modulus due to improved moisture resistance, it has various problems such as small internal loss, no lightweight diaphragm, and difficulty in changing the thickness inside the diaphragm. Have
There is also a diaphragm made by film molding or injection molding of a plastic material. However, since this diaphragm is a uniform material, the resonance frequency is concentrated at one point, resulting in a audible quirky sound. was there.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a method of manufacturing a diaphragm for a speaker, which has a large degree of freedom in molding shape and has good physical properties.

[0006]

In order to solve the above-mentioned problems, a method of manufacturing a diaphragm for a speaker according to the present invention comprises a nonwoven fabric containing a predetermined amount of thermoplastic resin fibers, which is made from a softening temperature of the thermoplastic resin fibers. Is also high and lower than the melting temperature.

Further, in the method for manufacturing a speaker diaphragm according to the present invention, a mold having a partially and continuously changed cavity thickness is used to form a non-woven fabric containing a predetermined amount of thermoplastic resin fiber into the thermoplastic resin. The thickness of the diaphragm is changed by hot press molding at a temperature higher than the softening temperature of the resin fiber and lower than the melting temperature.

Further, in the method for manufacturing a speaker diaphragm according to the present invention, a polymer material dissolved or dispersed in a solvent is applied to the speaker diaphragm after hot press molding manufactured by the above-described manufacturing method. And impregnated with it.

[0009]

[Function] A fiber obtained by thinly stretching a thermoplastic resin and molding it, even if it is below the melting temperature of the thermoplastic resin itself,
It is possible to partially melt by applying a large pressure. The extent of this melting is approximately proportional to the pressure exerted.

In view of this point, the present invention hot-press-molds a nonwoven fabric containing thermoplastic resin fibers at a temperature higher than the softening temperature of the thermoplastic resin fibers and lower than the melting temperature.

At this time, by partially and continuously changing the cavity thickness of the mold for forming the diaphragm, the partially and continuously changed pressure is applied to the nonwoven fabric sandwiched between the molds during thermoforming. Add. That is, the thermoplastic resin contained in the nonwoven fabric is melted according to the applied pressure.

That is, since a large pressure is applied to a portion having a small mold cavity thickness, the thermoplastic resin fibers contained in the nonwoven fabric in this portion are melted. As a result, it acts as a binder for other fibers to form a thin film. On the other hand, a large pressure is not applied to a portion having a large die cavity thickness, and the thermoplastic resin fibers contained in the nonwoven fabric in this portion hardly melt. As a result, the non-woven fabric becomes thick and has many voids.

That is, it is possible to obtain a diaphragm in which the thickness and the porosity are partially and continuously different in the same diaphragm.

Next, on the diaphragm thus obtained,
When a polymer substance dissolved or dispersed in a solvent is coated and impregnated, the impregnation rate is approximately inversely proportional to the porosity. Thus, by selecting various impregnating liquids, it becomes possible to obtain a diaphragm having a versatile structure in which a shape difference and a physical property difference are provided depending on the portion inside the diaphragm.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows a mold structure of a speaker diaphragm to which the manufacturing method of the present invention is applied, and FIG. 2 shows a body shape of the speaker diaphragm hot-pressed by this mold. Is shown.

The shape of the cavity 13 formed by the male mold 11 and the female mold 12 of the mold 1 is the inner diameter portion 21 of the diaphragm 2.
Is formed such that the thickness of the portion 131 corresponding to the inner diameter portion of the diaphragm 2 is large and the thickness of the portion 132 corresponding to the outer diameter portion 22 of the diaphragm 2 is small.
Has a cavity structure in which the thickness gradually decreases toward the outer diameter portion 22.

A non-woven fabric containing a predetermined amount of thermoplastic resin fibers is hot-press molded with the mold 1 having such a structure to produce a speaker diaphragm 2 having a structure shown in FIG.

The thermoplastic resin fiber (that is, the fiber obtained by thinly stretching the thermoplastic resin) is partially melted by applying a large pressure even when the temperature is not higher than the melting temperature of the thermoplastic resin itself. Is possible. Then, the degree of this melting is approximately proportional to the applied pressure.

That is, in this embodiment, since the thickness of the outer diameter portion 132 of the cavity 13 is made small, a large pressure is applied to the nonwoven fabric at this portion 132, and the thermoplastic resin fibers contained in this portion of the nonwoven fabric are It will be melted. As a result, in this portion 132 (outer diameter portion 22 in the speaker diaphragm 2), the thermoplastic resin fiber acts as a binder for other fibers, and becomes a thin film. On the other hand, since the thickness of the inner diameter portion 131 of the cavity 13 is increased, a large pressure is not applied to the nonwoven fabric in this portion 132, and the thermoplastic resin fibers contained in this portion of the nonwoven fabric hardly melt. Become. As a result, in this portion 131 (inner diameter portion 21 in the speaker diaphragm 2), the non-woven fabric has a large thickness and many voids.

That is, in the diaphragm 2, a diaphragm having a partially different and continuously different thickness and porosity can be obtained.

Next, the vibrating plate 2 thus obtained
When a polymer substance dissolved or dispersed in a solvent is applied and impregnated, the impregnation rate is approximately inversely proportional to the porosity. That is, in the inner diameter portion 21 of the diaphragm 2, the impregnation rate is small because the porosity is large, and in the outer diameter portion 22, the impregnation rate is large.

Thus, by selecting various impregnating liquids, it becomes possible to obtain a diaphragm having a variety of structures in which a difference in shape and a difference in physical properties are provided depending on the portion inside the diaphragm 2.

Next, the manufacturing method of the present invention will be described with reference to specific examples.

200 g / m 2 basis weight containing 20% of acrylic fiber having a fiber diameter of 2 denier as the thermoplastic resin fiber.
² of the nonwoven fabric, and molded at a temperature 160 ° C. at a mold shown in FIG. 1, to give a vibration plate 2 of the structure shown in FIG. At this time, the cavity 13 of the mold 1 was adjusted so that the molding thickness of the diaphragm 2 was 0.2 mm in the outer diameter portion 132 and 0.5 mm in the inner diameter portion 131. The outer diameter of the cavity 13 of the mold 1 was adjusted so that the outer diameter of the diaphragm 2 during molding was 12 cm. The heat distortion temperature (softening temperature) and the melting temperature of the acrylic resin are each 12
It is 0 degreeC and 230 degreeC.

When hot press molding was performed under these conditions, the acrylic fibers were melted in the outer diameter portion 22 of the diaphragm 2 to form a film-shaped thin leaf. Further, in the inner diameter portion 21, almost no melting of the acrylic fiber was observed, and the nonwoven fabric state with many voids was maintained. The diaphragm 2 thus obtained was impregnated with a urethane resin solution to prepare a final product.

FIG. 3 shows a caliber 12 which is the final product produced.
The frequency characteristics of the speaker in cm are shown.

In the above specific example, the content of the thermoplastic resin fiber is 20%, but at least 1
If it is 0% by weight or more, good results can be obtained.

[0029]

According to the method of manufacturing a speaker diaphragm of the present invention, a mold having a partially and continuously changed cavity thickness is used, and the speaker diaphragm is hot-press molded from a nonwoven fabric containing a thermoplastic resin. With such a configuration, it is possible to easily obtain a diaphragm having a shape difference and a physical property difference depending on the portion inside the diaphragm. That is, it is possible to easily obtain various types of diaphragms according to the use of the speaker.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a mold structure of a speaker diaphragm to which a manufacturing method of the present invention is applied.

FIG. 2 is a cross-sectional view showing the shape of a body of a speaker diaphragm that is hot press molded with the mold shown in FIG.

FIG. 3 is a graph showing frequency characteristics of a speaker manufactured by the manufacturing method of the present invention.

[Explanation of symbols]

 1 mold 2 diaphragm 13 cavity

Claims (3)

[Claims] 1. A speaker diaphragm, characterized in that a nonwoven fabric containing a predetermined amount of thermoplastic resin fibers is hot press molded at a temperature higher than the softening temperature of the thermoplastic resin fibers and lower than the melting temperature. Manufacturing method. 2. A non-woven fabric containing a predetermined amount of a thermoplastic resin fiber, which is higher in temperature than the softening temperature of the thermoplastic resin fiber, is formed by using a mold having a partially and continuously changed cavity thickness.
A method for manufacturing a speaker diaphragm, wherein the thickness of the diaphragm is changed by hot press molding at a temperature lower than the melting temperature. 3. A speaker diaphragm after hot press molding,
The method for manufacturing a speaker diaphragm according to claim 1 or 2, wherein a polymer substance dissolved or dispersed in a solvent is applied and impregnated.