JPH0378840B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a diaphragm for a speaker based on a woven or nonwoven fabric of high modulus fibers and a thermosetting resin, and an improved method for manufacturing the diaphragm.

Conventional diaphragms for speakers include diaphragms made by press-molding metal foil, paper fiber diaphragms obtained by papermaking, drying, resin impregnation, and heat pressing processes, and diaphragms made by impregnating woven fabric with excipients. Soft dome diaphragms that are heat-pressed and coated with damp material, or synthetic resin diaphragms that are vacuum- or pressure-formed from thermoplastic resin sheets, are often used, but each has advantages and disadvantages, and it is difficult to find a diaphragm that has the desired physical properties. I couldn't get it.

Therefore, in recent years, diaphragms based on highly elastic fibers such as carbon fibers and thermosetting resins have been considered, for example, diaphragms made by impregnating woven carbon fibers with thermosetting resins and heat-pressing them as prepreg materials. ing.

Some types of such diaphragms have the advantage of having a large Young's modulus of 2 to 3×10 ¹¹ dyn/cm ² and high rigidity.

On the other hand, as is well known, in a diaphragm, sometimes a frusto-conical diaphragm, corrugations are sometimes formed in the midsection of the diaphragm in order to increase the radial rigidity of the diaphragm.

Therefore, it is desirable to form corrugations in the diaphragm based on carbon fiber and thermosetting resin to further increase the rigidity. There is a drawback that when a small shaped part is formed by press molding, the fibers break and it is not possible to form a sufficient shape.

Therefore, the present invention provides a manufacturing method that enables molding of complex-shaped portions such as corrugation ribs made only of the thermosetting resin, or thickening only necessary portions, at the same time as press forming of the diaphragm. An example of a diaphragm having the above structure applied to a frusto-conical diaphragm having a carbon fiber woven fabric and an epoxy resin as a base will be described in detail below along with a manufacturing method.

In FIG. 1, reference numeral 1 is a prepreg material in which 40 wt% of epoxy resin is impregnated into a plain woven fabric made of fiber bundles in which 3000 long carbon fibers with a diameter of 8 to 9 μm are arranged in parallel.

Reference numeral 21 denotes a convex mold having a plurality of annular grooves 21b formed approximately in the middle of a truncated conical convex surface 21a, and 22 a concave surface 22a having a clearance corresponding to the thickness of the diaphragm to be formed between the convex surface 21a and the convex surface 21a. It has a concave mold.

Note that 21c and 22c are heaters for heating the molds, respectively.

The prepreg material 1 is sandwiched between these uneven molds 21 and 22, and the mold temperature is set to 130°C as shown in Fig. 2.
Press molding at a press pressure of 5Kg/cm ² .

At this time, the epoxy resin is once melted in the first stage of pressing, flows between the carbon fibers due to the pressing pressure, flows into the annular groove 21b, and remains there.

After the epoxy resin is cured by further heat pressing, the truncated conical diaphragm is removed from the mold.

The pressing time in the above process was about 20 minutes.

Then, the unnecessary parts are cut out to complete the truncated conical diaphragm.

As shown in FIG. 3, the thus obtained diaphragm 31 is made of epoxy resin only on the surface of the diaphragm 31a made of carbon fiber woven fabric and epoxy resin in the areas corresponding to the annular grooves of the convex mold. Corrugation ribs 31b are formed.

Therefore, the corrugation ribs 31b impart radial rigidity to the diaphragm 31, further increasing the inherent high rigidity of the diaphragm based on carbon fiber woven fabric and epoxy resin.

FIG. 3 shows another embodiment, in which a convex mold structure is used to obtain a diaphragm that increases the rigidity at the top of the truncated conical diaphragm, that is, the part where it connects to the coil bobbin, and increases the adhesive area with the coil bobbin. By providing an annular recess 41 at the top of the convex surface 21a of the convex mold 21, the clearance with the concave surface 22a of the concave mold 22 shown in FIG. 1 is made larger than other parts.

The pressing process can be carried out in the same manner as in the above embodiment, and the diaphragm thus formed has a bulge 31c made of only epoxy resin at the top of the diaphragm 31, as shown in FIG. As a result, the bonding area with the coil bobbin 51 increases and the bonding strength with the coil bobbin 51 increases, and the rigidity of the top of the diaphragm 31 increases due to the bulge 31c, so that the so-called bell vibration suppressing effect can be achieved. .

Furthermore, FIG. 6 shows another embodiment, in which a convex mold is used to form a locking protrusion for a dust cap which is usually attached near the top of this type of truncated conical diaphragm. By providing an annular groove 61 near the top of the convex surface 21a of the mold 21, the epoxy resin is held in the annular groove 61 by press molding as described above.

As shown in FIG. 7, a diaphragm press-molded using the convex mold 21 and the concave mold 22 shown in FIG. An annular locking edge 31 is formed, which makes positioning of the dust cap 71 extremely easy, and also allows the dust cap 7
The adhesive area with 1 increases, and the bonding strength between the two can be increased.

In addition, in this embodiment, the locking edge does not have to be annular, and may be, for example, an arcuate locking portion arranged in a circular shape, or at least three or more dot-like small protrusions arranged concentrically. This can be easily accomplished by changing the shape of the convex surface of the convex mold according to the manufacturing process of the present invention.

As explained above, the present invention provides a speaker diaphragm based on a woven fabric or non-woven fabric of high elastic fibers and a thermosetting resin, in which a recess is provided at a required portion on at least one surface of a press mold. Temporarily melted thermosetting resin is held during diaphragm molding, and the diaphragm is formed by heating and curing it, and the diaphragm portion corresponding to the recess is made of only the hardened thermosetting resin. A manufacturing method characterized by forming a protrusion and a diaphragm structure obtained by the manufacturing method. Furthermore, it becomes possible to form parts with complex shapes, such as corrugation ribs, which were previously impossible in the manufacturing method of diaphragms made of high elastic fibers and thermosetting resin. Furthermore, according to the diaphragm of the present invention, a diaphragm with higher rigidity can be obtained compared to conventional diaphragms made of high elastic fibers and thermosetting resin, and as shown in the examples, it is possible to obtain a diaphragm that is more rigid than the conventional diaphragm made of high elastic fibers and thermosetting resin. This has the advantage that the bond strength can be increased.

Furthermore, since it can be done simultaneously with the molding of the diaphragm, it has practical advantages such as being suitable for maximum mass production.

This invention has been explained above by exemplifying carbon fiber plain woven fabric and epoxy resin, but in addition to carbon fiber, woven fabrics or non-woven fabrics such as silicon carbide fiber, glass fiber, alumina fiber, poron tungsten fiber, etc. can be applied. Other phenolic resins, furan resins and similar thermosetting resins are applicable.

Other woven fabrics include twill weave, satin woven fabric,
It can also be applied to woven fabrics made of the above-mentioned high-elastic fibers, or to laminates of these.

Further, in the present invention, it is also possible to form radial ribs on the surface of the diaphragm in order to increase the rigidity of the diaphragm in the central axis direction.

Furthermore, the present invention is not limited to prepreg materials, but can be applied to any material in which a woven or nonwoven fabric made of highly elastic fibers is impregnated with a thermosetting resin prior to press molding.

[Brief explanation of drawings]

Fig. 1 is a cross-sectional view of a press mold according to an embodiment used in the structural method of the present invention, Fig. 2 is a cross-sectional view of the press mold showing the same molding state, and Fig. 3 is a schematic diagram of an embodiment of a diaphragm according to the present invention. FIG. 4 is an enlarged cross-sectional view of a convex mold of another embodiment used in the manufacturing method of the present invention, and FIG.
The figure is an enlarged cross-sectional view of the main part of a diaphragm according to another embodiment of the present invention, FIG. 6 is a cross-sectional view of a convex mold according to another embodiment used in the manufacturing method of the present invention, and FIG. 7 is a cross-sectional view of another embodiment of the present invention. FIG. 2 is an enlarged sectional view of a main part of an example diaphragm. 21 is a convex mold, 22 is a concave mold, 21b is an annular groove, 21c and 22c are heaters, 31 is a diaphragm, 31b is a corrugation rib, 41 is an annular recess, 31c is a bulge, and 61 is a concave mold. Annular groove, 31
d is an annular locking edge for locking the dust cap.

Claims (1)

[Scope of Claims] 1. In a speaker diaphragm made of a woven fabric or non-woven fabric of high elastic fibers and a thermosetting resin as a base, and formed into a desired shape by press molding, the thermosetting resin is applied to required portions on the surface of the diaphragm. A diaphragm for a speaker, in which a protruding portion made only of a synthetic resin is formed simultaneously with press molding of the diaphragm. 2. The diaphragm for a speaker according to claim 1, wherein the protrusion is an annular corrugation rib provided in the midsection of the diaphragm. 3. The diaphragm for a speaker according to claim 1, wherein the protrusion is a bulge that comes into contact with a coil bobbin formed at the top of the diaphragm. 4. Claim 1, characterized in that the protrusion is an annular protrusion, a concentric arc-shaped protrusion, or three or more concentric small protrusions for locking a dust cap formed near the top of the diaphragm. Diaphragm for the speaker described. 5 A woven fabric or non-woven fabric made of highly elastic fibers impregnated with a thermosetting resin is heated and press-molded using a press mold in which a recess is formed in a required portion of at least one mold surface to form a highly elastic fabric impregnated with the thermosetting resin. While forming a woven or non-woven fiber into the shape of a diaphragm,
The thermosetting resin, once melted during the press molding, is allowed to flow into the recess and then cured by heating, thereby forming protrusions made only of the thermosetting resin in required portions of the molded diaphragm. A method for manufacturing a speaker diaphragm characterized by: