JPS586359B2 - Manufacturing method of diaphragm - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a diaphragm using a metal fiber cloth or thin plate as a base material.

Generally speaking, thin plates used as speaker diaphragms must have high efficiency and good transient characteristics.In addition, in order to extend the treble range as a treble speaker diaphragm, the thin plates must have a small mass and a Young's modulus. In addition, the thin plate is required to be strong.

The present invention focuses on metals and their compound materials as materials that satisfy such requirements, and provides a novel method for manufacturing a subica diaphragm.

Therefore, the manufacturing method of the diaphragm of the present invention is to apply a compound capable of liberating carbon or carbide by thermal decomposition onto a cloth-like body made of metal fibers of a predetermined shape or a base material made of a thin metal sheet material, if necessary, in an inert atmosphere. It is characterized in that carbon or carbide is thermally decomposed in the presence of such a material to generate or precipitate carbon or carbide, and the carbon or carbide is deposited on a substrate, such as by filling the mesh of the cloth-like material.

The diaphragm manufactured by the method of the present invention exhibits better frequency characteristics and is superior in durability compared to diaphragms manufactured from conventionally used titanium Ti or aluminum AI alloys.

Furthermore, since the mechanical properties of the crystalline carbide, such as Young's modulus, can be controlled by the thermal decomposition temperature, it is possible to produce a distinctive diaphragm with desired acoustic properties by changing the speed of sound that propagates in the thickness direction of the diaphragm.

This invention will be described in more detail.

Among the base materials used in this invention, the cloth-like body made of metal fibers preferably has a mesh size of about 50 to 300 mesh.

If it is more than 300 mesh, the cloth material will be too thin and the strength of the product will be reduced.If it is less than 50 mesh, if carbon is precipitated until it fills the pores of the cloth material, the product will be too thick and the performance of the diaphragm will deteriorate. This is because it decreases.

The thickness of this cloth-like body or thin plate is preferably 10 to 200 μm, preferably 20 to 100 μm.

In particular, about 40 to 70 μm is desirable. If it is less than 10 μm, it is unsuitable as a diaphragm in terms of strength, and if it is 200 μm
This is because if it is more than that, it becomes heavy in terms of weight.

In this specification (including the claims), the term cloth-like body refers to all cloth-shaped fibers, including woven cloth,
It also includes nonwoven fabrics.

The method for producing a diaphragm of the present invention is to thermally decompose a compound capable of liberating carbon or carbide by thermal decomposition on the base material of the cloth or thin plate in an inert atmosphere.

In this specification (including the claims), an inert atmosphere means that it does not contain any active compounds other than compounds that can liberate carbon or carbide by thermal decomposition. This includes not only the case where the compound contains a compound capable of releasing carbide and an inert gas, but also the case where nothing other than the compound capable of releasing carbide by thermal decomposition is contained.

The purpose of generating or depositing carbon or carbide on a cloth or thin plate substrate in an inert atmosphere is to control the rate of precipitation of carbide onto the substrate.

The inert gas introduced into the reaction system to create this inert atmosphere is, for example, argon, helium, or nitrogen.

Compounds that can generate carbides include all compounds or mixtures that liberate carbon or carbides by thermal decomposition and precipitate on the substrate, and furthermore, compounds that can precipitate elemental carbon or other substances (metals, metal compounds, etc.) along with carbides. It shall include all compounds or mixtures that

That is, it includes not only carbides but also carbides and elemental carbons, carbides and elemental carbons and other substances (e.g. metals, metal compounds, etc.), or carbides and all compounds that precipitate other substances6. For example, methane, ethyl One or more of alcohol, butane, etc. and TiCI4, WC14
Examples include mixtures with one or more of metal compounds such as.

Examples of carbides obtained include Ti-C, B-C,
An example is Be-C.

The amount of inert gas can be increased or decreased in order to adjust the gas concentration in the reaction system of the compound capable of thermal decomposition (thereby liberating carbides).

The sum of the partial pressures of the inert gas and this gaseous compound is preferably normal pressure.

This is because no special seal is required to operate the device.

On the other hand, under a reduced pressure atmosphere, the decomposition temperature can be lowered, although the equipment becomes more complicated.

If plasma decomposition is used, it will decompose at 150℃~30℃
Alternatively, the M-C compound is precipitated, but diffusion heat treatment is required after the precipitation step.

If the partial pressure of this gaseous compound is too high, the precipitation rate of carbides on the base layer will be high, resulting in the precipitation of low-density and porous carbides, and if the partial pressure is too low, the precipitation rate of carbides will be too slow. It happens.

Therefore, the partial pressure of the gaseous compound can be determined functionally taking into account the above facts.

In order to manufacture a good product as the diaphragm of this invention, there are three steps.
It is preferably in the range of 0 to 200 mHr, and 100 mHr.
Particularly preferred is around mHg.

The inert gas is added to control this gaseous compound, and the entire reaction system is
Maintain the atmospheric pressure and keep the partial pressure of the gaseous compound constant.
By introducing an inert gas into the reaction system, carbide can be continuously deposited onto the substrate at a constant deposition rate.

It can be for diluting the gas to reduce the rate of deposition.

Pyrolysis to precipitate carbides on the substrate is 500-1
It is carried out at 500°C.

This is to deposit carbon or carbide on the base material.

When the base material is a cloth-like material, this carbide grows along the grains of the base material up to about 2 μm, but tends to grow in the direction of filling the grains beyond that with carbon.

The reason why the mesh of the cloth-like body is filled with carbon or carbide in this way is to eliminate air permeability and manufacture a diaphragm.

In the case of plates/substrates, it precipitates over the entire surface of the plate to increase its strength.

When the deposited substance is carbon, it reacts with the substrate to synthesize carbide.

According to the present invention, carbides with metals precipitated on a substrate by thermal decomposition are not particularly limited, but TiC. W.C. W2C,
BeC is preferably used.

The types of metals constituting the base material include Ti, Ti alloy, Be,
Examples include Be alloy, AI, and AI alloy.

The thickness of the carbide layer on this base material is preferably about 2 to 70 μm.

This is because if the thickness is less than 2 μm, the strength of the diaphragm decreases and desired frequency characteristics cannot be obtained.

If the thickness is 70 μm or more, the strength is sufficient, but the mass increases too much, resulting in disadvantages such as not being able to produce a sharp sound.

In order to obtain desired frequency characteristics, particularly for a high-frequency speaker diaphragm, the thickness of the carbide layer is preferably about 10 to 30 μm.

The density ρ of this carbide is about 2 to 7 (X10 3 kg/m), and the Young's modulus E is about 1 to 12 [X 10 11 N/m 2].

Therefore, titanium Ti (ρ4.54(XI03ky/
m3), El1.9 (XIO10N/m2] and aluminum (p2.7 (X103kg/m3, E7o5C
x1o”°N/m2], B/p can be large.

Therefore, it is an excellent material for diaphragms, especially high-pitched speakers.

After carbon or carbide is deposited on the base material, it is desirable to perform heat treatment to increase the density.

Such heat treatment increases the strength and durability of the diaphragm, and also improves the frequency characteristics.

However, this heat treatment is not essential in this invention.

Examples will be described below to make the invention easier to understand.

This embodiment shows one embodiment of the present invention, and can be arbitrarily modified within the scope of the present invention.

Example: A formed Ti metal plate (40 μm thick) is placed on a precipitation base of a predetermined shape (diaphragm shape) in a cylindrical furnace.

This precipitation base is made of graphite.

This is because heat-resistant materials must be used in consideration of the temperature in the furnace.

For example, common metals melt at temperatures of 1800 to 3000°C, and tungsten W does not melt, but since tungsten carbide WC is produced, a carbide-based precipitation base is optimal.

The thickness of this cloth-like body was 40 μm.

Moreover, this cloth-like body had 200 mesh.

After laying a Ti plate on the base for carbide precipitation,
iCI4, methane and argon were introduced into the furnace.

The partial pressure of methane was about 40 mmHr, and the sum of the partial pressures of argon, methane, and T+cI4 (ie, the atmospheric pressure inside the furnace) was 1 atm.

The temperature in this furnace was raised to 1000℃ using a high-frequency plasma flame.
and maintained at that temperature for approximately 15 minutes.

After the carbide was deposited on the substrate by vapor phase decomposition for about 15 minutes, methane gas and waste gas were discharged from the furnace.

The thickness of the carbide layer of the diaphragm manufactured in this way is approximately 5
It was μm.

Also, the density ρ of this carbide is 4,4CX103kl9/m
3), and Young's modulus E is 7.0 (X1011N/m3
)Met.

Further, the frequency characteristics of this diaphragm are as shown in the figure.

[Brief explanation of the drawing]

The figure is a graph showing the frequency characteristics of the diaphragm of the present invention.

Claims (1)

[Claims] 1. A method for manufacturing a diaphragm in which a compound is thermally decomposed to produce carbide on a base material made of a cloth-like material made of metal fibers or a thin plate material made of gold embroidery, and the carbide is integrated with this base material.