JP6312122B2 - Acoustic diaphragm made of wood material - Google Patents

Description

  The present invention relates to an acoustic diaphragm, and more particularly to an acoustic diaphragm made of a wood-based material.

  The acoustic diaphragm 1 used for the speaker of the acoustic device shown in FIG. 1 is a component for converting a change in the current flowing through the voice coil 2 into air vibration, and is an important component that greatly affects sound quality. is there.

  The characteristics required for the material used for the acoustic diaphragm 1 are that it is thin, has a high specific elastic modulus, has an appropriate sound propagation speed, has a large internal loss, and changes in humidity. Although there is no modification and durability is high, in order to satisfy these characteristics, development of diaphragms using various materials has been performed as shown in FIG.

Among the materials described above, an acoustic diaphragm made of a wood-based material has been proposed using bamboo fibers (see Patent Document 1).
However, the acoustic diaphragm made of bamboo fiber disclosed in Patent Document 1 pulverizes the bamboo into chips, and then mechanically defibrates the bamboo with a pressure kneader, and the obtained bamboo fiber is hot-pressed. Since it is manufactured through a complicated manufacturing process of molding, there is a problem in terms of cost, and in terms of performance, there is no advantage over other materials (because of its low elastic modulus, The propagation speed was slightly lower than that of other materials.

On the other hand, the present applicant has previously proposed a flow molding technique for a wood-based material for producing a three-dimensional shaped molded body from a section of a wood-based material in one step (see Patent Documents 2 and 3).
The flow molding technology for wood-based materials disclosed in Patent Documents 2 and 3 is the molding of a three-dimensional shape made of a wood-based material by changing the mutual positional relationship without breaking the fibers inherent in the wood-based material. Although the body can be molded, none of the three-dimensional molded bodies disclosed in Patent Documents 2 and 3 have the characteristics required for the material used for the acoustic diaphragm.

Japanese Patent No. 5104429 JP 2010-52426 A Japanese Patent No. 5327791

  In view of the above-mentioned knowledge, the present invention aims to provide an acoustic diaphragm made of a wooden material having characteristics required for a material used for an acoustic diaphragm by using a flow molding technique of a wooden material. And

In order to achieve the above object, an acoustic diaphragm according to the present invention is an acoustic diaphragm made of a wood-based material, and a piece of a wood-based material impregnated with a water-soluble phenol resin as a synthetic resin is molded with a mold. It is characterized in that it is fluid-molded by pressurizing in between, and is thinned and densified.

In this case, the sections of wood-based material impregnated with a said synthetic resin, which has heated to cause a curing reaction when pressurized between mold to divide the fibers woody material has originally Instead, it can be formed by changing the mutual positional relationship .

Further, the thickness can be 0.1 to 1 mm, and the density can be 1.30 g / cm ³ or more.

  The acoustic diaphragm of the present invention is formed by changing the mutual positional relationship without dividing the fiber originally possessed by the wood-based material by using the flow molding technology of the wood-based material, Because it is thin and highly densified, it is a specific requirement for materials used for acoustic diaphragms, it is thin, has a high specific elastic modulus, has an appropriate sound propagation speed, Satisfies that the loss is high, the humidity is not denatured, and the durability is high.

It is structure explanatory drawing of the speaker of an audio equipment. It is characteristic explanatory drawing of the raw material used for an acoustic diaphragm. It is explanatory drawing which shows the manufacturing method of the diaphragm for acoustics of this invention. It is an external view of the diaphragm for sound of the present invention. It is an organization chart of the diaphragm for sound of the present invention.

  Hereinafter, an embodiment of an acoustic diaphragm according to the present invention will be described together with a manufacturing method thereof.

FIG. 3 shows an embodiment of a method for manufacturing an acoustic diaphragm according to the present invention.
This acoustic diaphragm 1 is formed by changing the mutual positional relationship without breaking the fibers inherent in the wood-based material by using the flow molding technology of the wood-based material. A wood-based material W made of a piece of wood-based material impregnated with resin is fluid-molded by pressurizing it between molds consisting of an upper mold D1 and a lower mold D2, and is thinned and densified. Is.

  Here, the woody material means a lignocellulosic material containing lignin, hemicellulose, and cellulose, and herbs can be used in addition to woody materials. Specifically, herbs such as kenaf, corn, sugar cane, hemp, rush and rice can be used in addition to wood (wood) and bamboo such as cedar, pine and beech. Also, two or more of the above materials can be used in combination.

  In addition, as the synthetic resin impregnated into the wood material, a thermosetting resin or a thermoplastic resin that improves the fluidity of the wood material and exhibits a binder function with respect to the wood material can be used.

  Among these, various resins such as phenol, epoxy, unsaturated polyester, urea, melamine, diallyl phthalate, silicon, vinyl ester, polyimide, and polyurethane can be used as the thermosetting resin.

  In addition, thermoplastic resins include polyolefins such as acrylic, polyethylene and polypropylene, cyclic polyolefins, esters such as polystyrene and phthalates, polyvinyl chloride, polyvinylidene chloride, polyvinyl acetate, polytetrafluoroethylene, ABS, AS , Polyamide such as nylon, polyacetal, polycarbonate, modified polyphenylene ether, polybutylene terephthalate, polyethylene terephthalate, polyphenylene sulfide, polysulfone, polyethersulfone, amorphous polyarylate, liquid crystal polymer, polyetheretherketone, polyimide, polyamideimide, etc. Various resins can be used.

  The mold composed of the upper mold D1 and the lower mold D2 is configured so that a pressure of 100 to 300 MPa can be applied by a press machine such as a single-axis press, and can withstand this high load, and the wooden material W In order to ensure fluidity and releasability, for example, an alloy tool steel material is used, and the surface in contact with the wood-based material W is formed into a cone shape which is the shape of the acoustic diaphragm 1 to be manufactured, and the surface What processed and finished smoothly can be used conveniently.

  The mold is provided with a mold heating / cooling unit T, and the mold is heated from the outside (temperature corresponding to the synthetic resin to be used, for example, 100 to 250 ° C.) or cooled. The synthetic resin impregnated in the material can be cured and plasticized.

Hereinafter, the acoustic diaphragm of the present invention will be described based on more specific examples.
In order to randomize the fiber direction, bamboo samples (about 8 × 20 × 15 mm) and cedar, pine and beech samples (about 15 × 15 × 15 mm) were prepared as woody materials.
In this case, in order to control the fiber direction, it is possible to cut a bamboo (diameter of about 45 mm) and use a ring-shaped sample having a thickness (fiber direction) of about 3 mm.
The bamboo samples were removed from the skin and boiled by boiling.
This sample was impregnated with a water-soluble phenol resin (solid content concentration: 7.5% to 30%. In this example, 15%) by reducing the pressure and pressurizing (resin impregnation rate: 1 to 50%), 35 It was prepared as a wood-based material W by being dried by air drying at a temperature not higher than ° C.
Then, the wood-based material W is placed between the upper die D1 and the lower die D2, and the die is heated from the outside (in the present embodiment, about 150 ° C.) while being uniaxially pressed. The acoustic diaphragm 1 was formed by fluid forming by pressurizing (100 to 300 MPa in the present embodiment, about 150 MPa in this example), and thinning and increasing the density.

  Table 1 and Table 2 show the characteristic values of the molded acoustic diaphragm 1, FIG. 4 shows an appearance photograph of the molded acoustic diaphragm 1, and FIG. 5 shows the case where bamboo is used as the wood-based material. The structure photographs of the acoustic diaphragm are shown.

The formed acoustic diaphragm 1 is formed by changing the mutual positional relationship of the wood-based material by using the flow-forming technology of the wood-based material without dividing the fibers originally possessed by the wood-based material. , Thinned and densified (thickness: 0.1 to 1 mm, preferably 0.2 to 1 mm, density: 1.30 g / cm ³ or more, preferably 1.35 g / cm ³ or more, More preferably, from 1.40 g / cm ³ or more), it is specific that is required for a material used for an acoustic diaphragm, and it is thin and has a high specific modulus (dynamic modulus / density: 1 0.0 × 10 ⁶ Pa / g / cm ³ or more, preferably 2.0 × 10 ⁶ Pa / g / cm ³ or more, more preferably 3.0 × 10 ⁶ Pa / g / cm ³ or more), proper Sound propagation speed (sound propagation speed: 1000-80 0 m / s), large internal loss (tan δ: 0.03 or more, preferably 0.04 or more, more preferably 0.05 or more, 0.1 or less), no degeneration with respect to humidity change, etc., durability It was confirmed that the product satisfies the high properties.

  As described above, the acoustic diaphragm of the present invention has been described based on the embodiment thereof, but the present invention is not limited to the configuration described in the above embodiment, and may appropriately be included within the scope not departing from the gist thereof. The configuration can be changed.

  The acoustic diaphragm of the present invention is an acoustic diaphragm made of a wood-based material having characteristics required for a material used for an acoustic diaphragm using a flow molding technology of a wood-based material. The present invention can be suitably used for an acoustic diaphragm used for a speaker or the like.

1 Acoustic diaphragm 2 Voice coil D1 Upper mold (mold)
D2 Lower mold (mold)
T Mold heating / cooling unit W Wood material (section of wood material impregnated with synthetic resin)

Claims (3)

An acoustic diaphragm made of wood-based material, which is fluid-molded by pressurizing a piece of wood-based material impregnated with a water-soluble phenolic resin as a synthetic resin between molds to make it thinner and more dense An acoustic diaphragm characterized by being made. The sections of wood-based material and the synthetic resin impregnated state, and are not then heated to cause a curing reaction when pressurized between mold without cutting the fibers woody material has originally The acoustic diaphragm according to claim 1, wherein the acoustic diaphragm is formed by changing a mutual positional relationship . The acoustic diaphragm according to claim 1, wherein the acoustic diaphragm has a thickness of 0.1 to 1 mm and a density of 1.30 g / cm ³ or more.