JPS6313399B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of manufacturing a speaker diaphragm made of boron fiber reinforced synthetic resin.

Conventionally, as disclosed in JP-A-52-2427, for example, boron was deposited as a diaphragm material onto a diaphragm-shaped metal base by physical vapor deposition (PVD) or chemical vapor deposition (CVD). Speaker diaphragms, as disclosed in Japanese Patent Application Laid-Open No. 51-104820, speaker vibrations manufactured by coating a highly elastic metallic substance on a non-metallic fiber material and making or compressing this fiber material. The board is known.

In these speaker diaphragms, the specific modulus of elasticity E/ρ (E: Young's modulus, ρ density) is increased, and the internal loss is appropriately increased to extend the high range and reduce the dip in the frequency characteristics of the speaker. However, the properties were not fully satisfactory, and there were many practical problems in terms of mechanical strength, such as poor water resistance of the boron coating.

The purpose of the present invention is to eliminate the above-mentioned drawbacks and to
Furthermore, it is an object of the present invention to provide a method of manufacturing a speaker diaphragm that is acoustically excellent and easy to manufacture and handle by making full use of the excellent characteristics of boron.

Generally, a metal diaphragm has a high Young's modulus E, but its density ρ is also large, so the specific elastic modulus E/ρ is not very large.

Furthermore, there are limits to the improvement in specific elastic modulus and other properties that can be obtained by simply coating or laminating lightweight boron. Moreover, the hardness of the boron film is high and it is difficult to perform molding or other secondary processing.

Therefore, the method for manufacturing a speaker diaphragm of the present invention involves impregnating an epoxy resin into a cloth made by knitting or weaving thin carbon fiber wires coated with boron on the surface while heating with electricity by utilizing the conductivity of carbon fibers. It is molded under heat and pressure.

In other words, when an acrylic resin is heated from 800℃ to 1600℃ and a thin carbon fiber wire made into a carbonaceous substance is heated by directly applying electricity to it while flowing a boron halide such as Bcl3 using hydrogen gas as a carrier, boron is generated by the reaction 2Bcl3 + 3H2 → 2B + 6Hcl. Boron is released and adhered to the surface of the carbon fiber thin wire. In addition to such chemical vapor deposition, there is also a method of depositing metallic boron on the carbon fiber thin wire by ion plating, sputtering, or vacuum deposition.

Carbon fiber thin wires coated with boron are knitted and woven into a desired shape, impregnated with epoxy resin, and molded under heat and pressure.

The boron fiber-reinforced epoxy resin diaphragm obtained in this way is made of carbon fiber itself, which is a highly elastic material and is lightweight, and is coated with ultra-high elasticity and lightweight boron. The specific elastic modulus is 1.5 times higher, and the use of boron shows excellent properties such as a 50% increase in stiffness with a 5% increase in weight. Also, compared to a metal diaphragm, such as an aluminum alloy (dillerumin) diaphragm, the
% weight is reduced.

Moreover, since boron is a brittle material that breaks easily and has high hardness, it is made by weaving boron monofilament with a 10-20 micron coating on 6-8 micron carbon fiber thin wire.
By knitting and weaving it in advance into a shape that approximates the shape of the diaphragm, there is no possibility that the boron coating would be broken during heating and pressure molding, resulting in a decrease in Young's modulus.

Furthermore, since the entire structure is impregnated with epoxy resin, the interlayer shear strength of the boron layer is as high as 10 to 11 Kg/mm ² , so there is no possibility of peeling or damage caused by moisture.

As described above, according to the present invention, the carbon fiber thin wire is directly energized by utilizing its conductivity, so that it becomes heated from the inside and becomes susceptible to reaction, so its surface is coated with boron extremely firmly. It is possible to obtain an extremely high specific modulus of elasticity by using carbon fiber, which is lightweight and has high elasticity, and boron, which is lightweight and has ultra-high elasticity.

Since we knit and weave a material with extremely high elasticity and a high Young's modulus while taking advantage of its properties, and impregnated and molded it with synthetic resin, it has a moderately high internal loss, so when used as a speaker diaphragm, The high frequency range is significantly extended, resulting in excellent flat frequency characteristics with little dip.

Claims (1)

[Claims] 1. Applying electricity to and heating the carbon fiber thin wire, depositing boron on the surface of the carbon fiber thin wire by physical vapor deposition or chemical vapor deposition, knitting and weaving the boron-coated carbon fiber thin wire, and impregnating this with epoxy resin, A method of manufacturing a speaker diaphragm by molding it under heat and pressure.