JPS59221100A - Speaker diaphragm and its production - Google Patents

Abstract

PURPOSE:To improve further the high rigidity that is proper to a diaphragm containing a base material made of carbon fiber and epoxy resin by forming a projected part at a desired area on the surface of the diaphragm only by thermosetting resin when the diaphragm is made by a press molding process. CONSTITUTION:The epoxy resin is impregnated by 40wt% into the plain woven fabrics of a two containing 3,000pcs. of carbon filament of 8-9mum arrayed in parallel to obtain a prepreg member 1. A convex metal mold 21 has plural annular hollow grooves 21b formed at approximately halfway of a truncated circular cone convex surface 21a. While a concave metal mold 22 has a clearance concave surface 22a equivalent to the thickness of a diaphragm to be formed as well as the surface 21a of the mold 21. These molds are heated by heaters 21c and 22c to undergo the press molding at 130 deg.C metal mold temperature and with 5kg/cm<2> pressing pressure. Thus a diaphragm 31 is made of the carbon fabric and epoxy resin. Such diaphragm 31 has a corrugation rib 31b made of only epoxy resin at the area corresponding to the groove 21b of the mold 21.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a diaphragm for a speaker based on a woven or nonwoven fabric of highly elastic 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. Nft dome diaphragms that are heat-pressed and coated with Rinpu It, or synthetic resin diaphragms that are vacuum- or pressure-molded from thermoplastic resin sheets, etc., are often used, but each has advantages and disadvantages and has the desired physical properties. I couldn't get the diaphragm.

Therefore, in recent years, diaphragms based on highly elastic fibers such as carbon fiber and thermosetting resin have been considered, for example, diaphragms made by impregnating a woven carbon fiber cloth with thermosetting resin and heat pressing it into prepreg material. It is being

Some types of such diaphragms have a Young's modulus of 2 to 3.
It has the advantage of having a large value of X 1011 dyn/cy71 and high rigidity.

On the other hand, as is well known, in a diaphragm, particularly a truncated 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 a diaphragm made of carbon fibers and thermosetting resin to further increase the rigidity. If a shaped part is tried to be formed by press molding, the fibers will break and a sufficient shape cannot be obtained.

Therefore, the present invention provides a manufacturing method and a manufacturing method that can simultaneously form complex-shaped parts such as corrugation ribs made only of the thermosetting resin, or thicken only necessary parts, at the same time when the diaphragm is press-molded. An example of a diaphragm having the above structure, which is 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 denotes a prepreg material made by impregnating 40 wt of a woven poxy resin into a plain-woven fabric made of 3000 long carbon fibers with a diameter of 8 to 9 μm arranged in parallel.

21 is a truncated conical convex surface 2], a convex mold having a plurality of annular grooves 21b formed approximately in the midsection of a, and 22 is a convex mold having a convex surface 21a of the convex mold 21 and the thickness of the diaphragm to be molded. It is a concave mold having a concave 1Tii22a with a corresponding clearance.

Note that 2]c and 22c are heaters for heating the respective molds.

The prepreg material 1 is sandwiched between such uneven molds 21 and 22, and the mold temperature is 130°C and the press pressure is 5.
Press molding at Kg/ai.

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 2, and remains there.

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

The pressing time in the above step 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 has a diaphragm 31a made of carbon fiber woven fabric and an epoxy resin, with epoxy resin applied to the surface of the diaphragm 31a in areas corresponding to the annular grooves of the convex mold.
Corrugation ribs 31b made of only decoy fat are formed.

Therefore, the radial rigidity of the diaphragm 31 is reduced by one dimension due to the corrugated ribs ('311), and the high rigidity inherent to the diaphragm based on carbon fiber woven fabric and epoxy resin is further enhanced.

Figure 3 shows an example of a pond, and a diaphragm is obtained which increases the rigidity of the truncated circle 9 (the top of the diaphragm, that is, the part where it joins with the coil bobbin) and increases the adhesive area with the coil bobbin. A convex mold (14 structure) is provided, and by providing an annular recess 41 at the top part 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. It is also enlarged.

The pressing process can be carried out in the same manner as in the above embodiment, and the diaphragm thus molded has a bulge 31 made only of epoxy resin at the top part of the diaphragm 31, as shown in FIG.
c is formed, which increases the bonding area with the coil bobbin 5 and increases the bonding strength with the coil bobbin 51. At the same time, the rigidity of the top of the diaphragm 31 increases due to the bulge 31-C, resulting in a so-called The effect of suppressing bell vibration can be achieved.

Furthermore, FIG. 6 shows another embodiment, in which a convex mold is used to form a locking protrusion for Tasto Camp, which is usually attached near the top of this type of truncated circular diaphragm. By providing an annular groove 6 near the top of the convex surface 21θ of the mold 21 and performing press molding as described above, epoxy resin is retained in the annular groove 61 portion.

Using the convex mold 21 and the concave mold 22 shown in FIG. An annular locking edge 31 made of chisel is formed, which makes it extremely easy to position the dust cap 71, and increases the adhesion area of the dust cap 717, thereby increasing the bonding strength between the two.

In this embodiment, the locking edge may not be annular, and the locking edge may be an arcuate locking portion arranged in a circular manner, or at least three or more IUs arranged concentrically. It may be a point-like small protrusion, and this can be easily achieved by the manufacturing process of the present invention by changing the shape of the convex surface of the convex mold.

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 four parts are provided at required portions on at least one surface of a press mold. A thermosetting resin that is temporarily melted during diaphragm molding is fixed to the four parts, and the diaphragm is formed by heating and curing it, and the diaphragm parts corresponding to the four parts are made only of 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 the conventional vibration plate made of high elastic fiber and thermosetting resin. It has the advantage of increasing the bonding strength with the diaphragm, and also has the second practical advantage of being suitable for mass production since it can be done simultaneously with the molding of the diaphragm.

This invention has been explained below 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, boron tungsten fiber, etc. can also be applied. In addition to nuepoxy resins, phenolic resins, furan resins and similar thermosetting resins are applicable.

In addition, woven fabrics such as twill weave, satin woven fabric, woven fabric made of the above-mentioned high elasticity fibers, or laminated fabrics of these can also be used.

Furthermore, 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 thermosetting resin is impregnated into a woven or nonwoven fabric made of highly elastic fibers prior to press molding.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of a press mold according to an embodiment used in the manufacturing method of the present invention, FIG. 2 is a cross-sectional view of the press mold showing the same molding state, and FIG. FIG. 4 is a cross-sectional view of another embodiment of a convex mold used in the manufacturing method of the present invention. FIG. 5 is an enlarged cross-sectional view of a main part of a diaphragm according to another embodiment of the present invention. FIG. 7 is a sectional view of a convex mold according to another embodiment of the present invention, and FIG. 7 is an enlarged sectional view of a main part of a diaphragm according to another embodiment of the present invention. 21 is a convex mold, 22 is a concave mold, 2]l] is an annular enclosure,
21c1〆2' 2c is a heater, 31 is a diaphragm, 3'lb is a corrugation rib, 41 is an annular recess, 31c is a bulge, 6] is an annular groove, and 31d is for locking the dust camp. It is an annular locking edge. and ([1辷7・BiI-1h

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, a desired portion on the surface of the diaphragm. A diaphragm for a speaker, wherein a protrusion made of only the thermosetting 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 protruding portion is a bulge that comes into contact with a coil bobbin formed on 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 formed near the top of the diaphragm for locking the diaphragm. Lively board for the speakers listed. 5. A press mold in which a recess is formed in a required part of at least one mold surface using a high elastic fiber FFA6 impregnated with a thermosetting resin or a non-woven fabric; i-press molded Jl cow, high rjjp property d 1i impregnated with the thermosetting resin
(The woven fabric or non-woven fabric of f- is formed into a diaphragm shape, and the thermosetting resin, which was once melted during the press molding, is allowed to flow into the recess and hardened by subsequent heating, and the formed diaphragm 1. A method for producing a diaphragm for a speaker, comprising forming a protrusion made only of thermosetting sebum at a required portion of the diaphragm.