JPS61201652A - Baffle for speaker and manufacture - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] "Industrial application field" This invention relates to improvements in speaker baffles.

``Prior Art'' Conventionally, the materials used to construct speaker baffles, that is, speaker boxes (box-shaped baffles) and baffle plates (plate-shaped baffles), have been made of natural wood veneer or plywood, and even wood chips made of synthetic resin. Hardened particle board is often used, and materials other than wood materials include synthetic resin mixed with an inorganic filler, aluminum casting, etc.

"Problems to be Solved by the Invention" Generally, materials used for speaker baffles have a great influence on the sound quality of the reproduced sound, and are required to have the following performance. In other words, (a) It has a large elastic modulus and high rigidity.

(b) High density and good sound insulation.

(c) Large internal loss and high vibration damping rate.

(d) There should be little shrinkage and warping, and there should be no gaps over a long period of time.

(e) Excellent workability.

(f) It must have functional beauty as an interior design.

etc.

When we examine the above conventional products from the viewpoint of these required performances, we find that those using wood materials have low density and elastic modulus, so they tend to resonate due to speaker vibration or sound pressure inside the box. Since the internal loss is small, the plate vibration damping is small. In recent years, due to the depletion of wood resources, it has become difficult to obtain high-quality wood materials, and at the same time, prices have soared. Also,
The current situation is that it is difficult to combine sufficient rigidity and internal loss with materials other than wood.

Furthermore, the trend in speaker systems in recent years has been to install large-diameter speaker units in relatively small cabinets and drive them with high output, so the rigidity of the speaker baffle and the internal loss , requirements for mechanical properties such as strength have become extremely strict.

The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a speaker baffle that solves the conventional drawbacks and can meet high requirements regarding material properties.

"Means for solving the problem" The speaker baffle according to the present invention has a base material with a specific gravity of 1.
．． 5 to 4.0, a bending strength of 50 MPa or more, and an elastic modulus of lθ to 50 GPa.

In the inorganic hardening material used in the present invention, hydraulic cement refers to a substance that solidifies or hardens in the presence of water, including alumina cement, calcium aluminate cement, portland cement mixed cement, quick-acting cement, There are granulated blast furnace slag, pozzolan, gypsum, etc.
Water-soluble copolymers that have a lubricating or dispersing effect on cement particles include 50-90% hydrolyzed vinyl acetate,
In addition to polyacrylamide, hydroxypropyl, and methylcellulose, there are lignosulfonates, sulfonated naphthalene salts, carboquine group-containing polymers, etc. In addition, glycerol, alkylene glycol, etc. are added as plasticizers.

In addition, the inorganic filler added as necessary refers to particle size 2
00 micron or less ferrite powder, silica hume,
Examples include alumina, natural sand, crushed sand, artificial lightweight aggregates (for example, crushed glass and ceramics, etc.), artificial lightweight aggregates (for example, vermiculite perlite, expanded slag, expanded shale, etc.), and the like. Similarly, water-dispersible organic polymers added as needed include latex, which can be mixed with hydraulic cement,
Namely, natural rubber latex, styrene-butadiene latex, acrylonitrile-butadiene latex, methyl methacrylate-butadiene latex, chloroprene latex, agrilate latex, vinyl acetate latex, persadecyl vinyl ester latex, propion. Examples include a mixed latex of one or more of vinyl acetate ester latex, vinyl chloride latex, and vinylidene chloride latex, as well as rubber powder and plastic powder.

After these materials are mixed in advance, they are kneaded using a twin roll mill or continuous kneader using high shear force until a homogeneous and plastic dough (highly refined product) is obtained, and then calendered and extruded. , 40-120℃ after molding by injection molding, mold press molding, etc.
The material is heated or steam-cured to become an inorganic hardened material.

"Operation" The inorganic hardened material constituting the speaker baffle of the present invention has extremely few voids and is obtained by mixing hydraulic cement with a water-soluble organic polymer as a thickener and kneading at a low water-to-cement ratio. It is a hardened material, and the combination of rigidity expressed by specific gravity and elastic modulus, and internal loss expressed by vibration damping rate, etc., has excellent characteristics that cannot be obtained with other materials.

Further, by mixing an inorganic filler, a water-dispersible organic polymer, etc., it has the advantage that the combination of rigidity and internal loss of the cured product can be selected arbitrarily to some extent. for example,
Adding ferrite can increase internal loss.

Quantitatively, the inorganic cured material constituting the speaker baffle of the present invention has a porosity of 20% or less, a maximum pore diameter of 100 microns or less, and particles with 2% or less of pores exceeding 15 microns that are extremely dense. It has a truly filled structure, and has a high bending strength of 50 to 200 MPa, compared to the 4 to 5 MPa of conventional hydraulic materials, and has an elastic modulus of 10 to 50 Pa. .

In addition, according to the present invention, it is also possible to use a laminated sheet of the above-mentioned cured inorganic material or a cured inorganic material reinforced with fibers, and it is possible to further improve the performance.

This inorganic cured product can be easily processed by cutting, drilling, etc. with a diamond tool, and can be easily bonded with an epoxy adhesive, an acrylic adhesive, or the like.

Furthermore, it is possible to add color or pattern by mixing a small amount of pigment during kneading, and it is also possible to create undulations on the surface by bringing a corrugated caul plate into contact during pressure molding.

Furthermore, when molding the parts that make up the speaker box (box-shaped baffle), ribs (m-shaped or vertical or horizontal crosspieces) are added to the inner surface of the speaker.
Or, by providing protrusions such as conical or pyramidal shapes, or by forming the constituent members themselves into a full gate shape, it is easy to improve rigidity, reinforcing effect, weight reduction, sound absorption effect, vibration damping performance, etc. be able to.

Furthermore, the surface of this inorganic hardened material can be polished to a marble-like luster, and can be painted with various paints, so the resulting speaker baffle has a beautiful appearance that can be appreciated as furniture. It also has the advantage of being easily obtained.

Possible manufacturing methods are listed below.

(a) After forming into a plate and hardening, process it using a lathe etc.
Assemble with adhesive.

(b) Form into a plate, make holes with a cutter etc. while still plastic, and assemble after hardening.

(C) Only the parts that require processing are formed using press molding (mold molding), and assembled after hardening.

(d) Integrally mold by injection molding, press molding, etc., excluding either the baffle plate or the back plate.

(e) Add ribs, conical or pyramidal projections to the surface that will become the inside of the speaker during press molding. As a result, it is possible to provide properties such as reinforcement, increased rigidity, weight reduction, and sound absorption effects.

(r) It is possible to create a plate with unevenness on the press plate during hot pressing.

(g) It is possible to embed assembly fittings such as screws and nuts during plate forming.

(h) It is possible to add color or pattern by mixing pigments. As a result, marble patterns, wood grain patterns, etc. are also possible.

(i) The beautiful appearance of stone can be obtained by polishing the surface.

As described above, according to the present invention, the following parts are constructed from the above-mentioned inorganic cured product.

It exhibits excellent performance, being relatively lightweight and rigid (hard to vibrate due to high specific gravity and elastic modulus), and high internal loss (high vibration damping rate, i.e. damps quickly even if it vibrates). , and a beautiful speaker.

A baffle for - is obtained.

"Example!" Alumina cement (manufactured by Denki Kagaku Kogyo; Alumina cement No. 2); 100 parts by weight, water; tt, parts by weight of S, vinyl acetate (manufactured by Nippon Gosei Kagaku Kogyo, Gohsenol KH-179)
After pre-mixing 0.7 parts by weight of glycerin by hand, kneading it using a twin roll mill and forming it into a thin plate at 80°C and 30 kg/cm2 for 10 minutes.
After heating and drying for 16 hours at 80℃, the thickness of the speaker box is 10mm.
A plate-shaped cured body of mm was obtained.

The physical properties of this cured product include a specific gravity of 2.3 and a bending strength of 140 MP.
a.

The elastic modulus was 40 GPa.

This plate-shaped hardened body was cut into a predetermined shape using a diamond blade cutter, and speaker mounting holes were formed using a lathe using a carbide cutting tool and a drilling machine using a concrete drill. A sealed speaker box (box-shaped baffle) for a full-range speaker was assembled using Konishi Bond's Bond Quick Set. To install the speaker unit (UP3 made by Fostyphus), glue a 31mm thick aluminum frame to the back of the baffle board, cut screws into this, and fix it to the baffle board with bolts via a 1mm thick raw rubber sheet. It was done by method. The surface of this speaker box was sanded with 400-grit sandpaper to give it a rustic brown color (depending on the color of alumina cement No. 2).
We were able to obtain a richly textured surface with a marble-like luster.

"Example 2" Alumina cement (manufactured by Lafarge; Sekar 71)
, 97 parts by weight were mixed with 3 parts by weight of carbon black as a black pigment, 9.8 parts by weight of water, parts by weight of polyvinyl acetate (manufactured by Nippon Gosei Kagaku Kogyo; GOHSENOL KH-173), and 7 parts by weight of glycerin. After pre-mixing with a Hobart mixer, kneading and forming into a sheet using a twin roll mill, heat pressing at 80℃ and 30Kg/cm2 for 10'' minutes, and heating and drying at 80℃ for 16 hours to form a baffle plate. A plate-shaped cured body with a thickness of 15 m+n for use as a speaker box and a plate-shaped cured body with a thickness of 12 cm for members other than the baffle plate of a speaker box were prepared.

The physical properties of this cured product are a specific gravity of 2.4 and a bending strength of 150 MPa.
, the elastic modulus was 45 GPa.

This plate-shaped cured body was cut into a predetermined shape using a diamond cutter, and speaker mounting holes were made on the baffle plate using a lathe and a drill press, and then an epoxy adhesive (manufactured by Konishi Bond; E-25 A 2-way bass reflex speaker box was assembled using 1).The surface was polished with 180-grit and 400-grit sandpaper.
Furthermore, by polishing with a compound, a black stone-like luster was obtained.

Speaker units (FT55D and FW200, manufactured by Fostyphus) were attached to this speaker box, and trial listening was performed. To install the speaker unit,
This was done by gluing nuts to the back side of the baffle plate and tightening them with bolts through a 2 mm thick raw rubber sheet. A predetermined band division circuit was installed inside the speaker box, and an appropriate amount of glass wool was pasted inside as a sound absorbing material. The results of the listening test showed that there was very little distortion in the bass range due to the plate vibration of the speaker box, and the bass was deep and firm, and combined with its appearance, it gave a strong impression of high rigidity. .

"Example 3" A cured product containing ferrite powder mixed as an inorganic filler was prepared, and its physical properties were measured. The material is alumina cement (manufactured by Denki Kagaku Kogyo; Denkano 1 Alumina Cement); 60
Parts by weight, ferrite powder (specific gravity 4.80); 66 parts by weight (addition of 40% internal cutting by volume), water; 11.5 parts by weight, polyvinyl acetate (manufactured by Nippon Gosei Kagaku Kogyo; Gohsenol Kt)
l-17s) Nia weight part, glycerin; 0.7 weight part.

These materials were mixed, premixed by hand, kneaded using a twin roll mill, formed into a sheet, and
°C, 30Kg/cm2 for 10 minutes, and heat-dried at 80C for 16 hours to a thickness of 3n.
A cured product for testing of +++++ was obtained.

The physical properties of this cured product are a specific gravity of 3.2 and a bending strength of 125 MPa.
, and had high rigidity with an elastic modulus of 47 GPa.

"Example 4" In order to increase the internal loss, a cured product was created in which synthetic rubber latex was mixed as a water-dispersible organic polymer,
Physical properties were measured. The materials and composition used were alumina cement (manufactured by Denki Kagaku Kogyo; Denka Alumina Cement 2).
No.); 90 parts by weight, styrene-butadiene rubber latex (manufactured by Japan Synthetic Rubber; Tomatsuku 500, solid content weight ratio 50% for polymer cement); 20 parts by weight (addition of 10% solid content by weight ratio), water ; 1.5 parts by weight (11.5 parts by weight including water contained in latex), polyvinyl acetate (Nippon Gosei Chemical Industry; Gohsenol K1l-17s
), 7 parts by weight, and glycerin: 0.7 parts by weight.

These materials are mixed, premixed by hand, kneaded using a twin roll mill, formed into a sheet, and
Heat pressed at 0℃, 30Kg/cm' for 10 minutes, and heated and dried at 80℃ for 16 hours to a thickness of 3m.
A cured body for testing was obtained.

The physical properties of this cured product are: specific gravity 2.11, bending strength 90 MPa,
It had both moderate rigidity with an elastic modulus of 15 GPa and high deformation performance.

"Effects of the Invention" As explained above, according to the present invention, it is possible to easily obtain a speaker baffle that can meet high requirements regarding material properties.

Claims (9)

[Claims] (1) At least a portion thereof is made of an inorganic hardened material having a bending strength of 50 MPa or more obtained by kneading, molding, and drying a mixture consisting of at least hydraulic cement, water, and a water-soluble copolymer using high shear force. A baffle for a speaker, characterized in that it is formed with. (2) A mixture consisting of hydraulic cement, water, and a water-soluble copolymer is added with an inorganic filler, a water-dispersible organic polymer, a water-dispersible organic polymer, or a fibrous reinforcing material. The baffle for a speaker according to claim 1, wherein the baffle is a baffle for a speaker according to claim 1. (3) Claim 1 characterized by being box-shaped
The speaker baffle according to item 1 or 2. (4) Claim 1 characterized in that it is plate-shaped.
The speaker baffle according to item 1 or 2. (5) Claim 3, characterized in that the baffle plate, back plate, side plate, top plate, and bottom plate constituting the box-shaped baffle are each formed and processed separately from an inorganic hardened material. Baffle for speakers described in. (6) The main body part excluding either the baffle plate or the back plate is molded from an inorganic hardened material,
4. The baffle for a speaker according to claim 3, wherein a baffle plate or a back plate separately molded from an inorganic hardened material is integrally attached to the main body portion. (7) At least a portion thereof is formed by a plate material formed by laminating a thin plate-like inorganic cured material and a thin plate-like damping material made of an organic polymer or the like or a thin plate-like reinforcing material made of fibers. A baffle for a speaker according to any one of claims 1 to 4. (8) kneading a mixture of hydraulic cement, water, a water-soluble copolymer, and optionally an inorganic filler, a water-dispersible organic polymer, or a fibrous reinforcing material under high shear; A method for manufacturing a speaker baffle, which comprises forming the kneaded material into a plate or box shape and drying the kneaded material to obtain a plate or box-shaped speaker baffle having a bending strength of 50 MPa or more. (9) 100 parts by weight of at least one type of hydraulic cement, 2 to 25 parts by weight, preferably 8 to 16 parts by weight, and 1 to 15 parts by weight, preferably 4 to 15 parts by weight of at least one water-soluble copolymer. A mixture of 10 parts by weight and, if necessary, an inorganic filler, a water-dispersible organic polymer, a fibrous reinforcing material, or a pigment for coloring, is made into a plastic dough by kneading means using high shear force. 9. The method of manufacturing a baffle for a speaker according to claim 8, wherein the dough is formed into a plate-like or box-like shape and then subjected to pressure and heat drying.