JPH0312517B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a diaphragm for a speaker, in which a surface material is attached to the surface of a core material having a large number of irregularities, which is formed by molding a thermoplastic resin film in vacuum, pressure, or vacuum pressure. The purpose is to provide a method of manufacturing a speaker diaphragm that can increase the strength without significantly compromising weight reduction.

In general, most speaker diaphragms are made of paper pulp, and the diaphragm has a cone shape. Therefore, the position of the sound source is different between the inner circumference and the outer circumference of the speaker diaphragm, creating a phase difference, making it difficult to obtain a speaker with flat frequency characteristics. On the other hand, a speaker with a flat diaphragm does not have the front chamber effect seen in cone-shaped speakers, and is advantageous in flattening frequency characteristics. In the case of a flat plate speaker, when a conventional paper diaphragm is used as a diaphragm, split vibration tends to occur due to its low bending rigidity, making it impossible to obtain flat characteristics over a wide band. In order to increase the bending rigidity with a flat plate, a sandwich structure can be considered. Sandwich structure diaphragms made of aluminum honeycomb have been widely used so far, but aluminum honeycomb is expensive due to its complicated manufacturing process, and is used in popular stereo equipment, radio receivers, television receivers, etc. It is difficult to use as a speaker. In addition, in order to obtain a diaphragm with a sanderch structure at low cost, a thermoplastic resin film is made into a core material with many irregularities by vacuum, air pressure, or vacuum pressure forming, and a surface material is pasted on both sides of this core material to vibrate. There is a way to make it into a board. In this case, since the core material has a portion parallel to the surface material, there is a portion that overlaps with the surface material, which is not efficient in terms of weight. Therefore, the convex portions of the formed film are cut to reduce the weight of the diaphragm and increase efficiency.

FIG. 1 shows a conventional method of manufacturing a speaker diaphragm. In FIG. 1, 1 is a thermoplastic resin film, and 2 is a mold. The molding die 2 has a concavo-convex pattern and a first die 3 having suction holes at the bottom of the concave portion, and a first die 3 having a concavo-convex pattern and a concave-convex pattern having the same pattern as the concave portion and the same size as the concave portion. It is composed of a stack of second molds 4 having through holes. In this manufacturing method, as shown in FIG. 1a, the thermoplastic resin film 1, which has been softened by heating in advance, is placed facing the above-mentioned molding die 2, and in this state, as shown in FIG. 1b, The thermoplastic resin film is molded using a mold 2 consisting of a combination of the first and second molds 3 and 4, and the first mold 3 is removed as shown in FIG. 1c. The convex portion of the film protruding from the second mold 4 is cut along the second mold 4 with a knife blade or the like, and then the core material 5 is cut as shown in FIG.
Surface materials 6 and 7 are adhered to both sides of the surface. However, although this method allows the weight of the diaphragm to be reduced, since the cut end face of the core material is an extremely thin film, the adhesive area with the surface material is small and the adhesive strength is weak. For this reason, there was a problem that sufficient reliability as a speaker could not be ensured.

The present invention eliminates such conventional drawbacks, and includes a first mold having an uneven pattern and a through hole having the same pattern as the first mold but wider than the width of the concave portion of the first mold. A second mold is combined with a second mold having two concave sections as a whole, and the thermoplastic resin film is vacuum-, pressure-, or vacuum-press-formed using this mold to form a core material having a large number of irregularities. , after taking out the second mold of the molding mold together with the molded core material, the convex part of the core material protruding from the second mold is cut and removed, leaving a part of the core material parallel to the surface material. After that, surface materials are bonded to both sides of the core material. According to this manufacturing method, by cutting the part of the core material molded in two stages that protrudes from the second mold along the second mold, a part of the part parallel to the surface material is pasted.・・・
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Because it is possible to remove unnecessary parts at the same time, it has the advantage of increasing strength without reducing weight or causing too much damage.

Hereinafter, a method for manufacturing a speaker diaphragm according to the present invention will be described with reference to drawings of embodiments.

FIGS. 2 and 3 show an embodiment of the present invention. In FIGS. 2 and 3, 11 is a thermoplastic resin film, and 12 is a mold. This molding die 12 includes a first die 14 having a predetermined pattern of concavo-convex portions and a suction hole 13 at the bottom of the concave portion, and a first die 14 having the same predetermined pattern as the predetermined pattern of the first die 14 and the above-mentioned pattern. First mold 14
The second mold 16 has a through hole 15 wider than the width of the recess.
It has a stepped recess 17. Here, the predetermined pattern consisting of the uneven parts of the molding die 12 is as shown in FIG.
are arranged alternately in the circumferential direction, and the recesses 17 have a two-stage structure.

Specifically, a polyarylate resin film with a thickness of 100 μm is used as the thermoplastic resin film 11, and this polyarylate resin film is heated at approximately 350°C.
After heating it to soften it, it is placed on a mold as shown in Figure 2a, and in this state it is expanded in the radial direction by sucking air through the suction holes 13 as shown in Figure 2b. A core material 19 having a pattern shape having concavities and convexities alternately in the circumferential direction was molded. Thereafter, as shown in FIG.
The convex portion of the core material 19 protruding from the core was cut with a knife blade, and the core material cut to a diameter of 28 mm was taken out. The weight of this heartwood was 65 mg. Incidentally, the weight of the core material obtained by the conventional vacuum forming method of vacuum forming using a mold having an uneven pattern in which uneven parts expanding in the radial direction are arranged alternately in the circumferential direction was 74 mg. As is clear from this comparison, the core material of this example is lighter than the core material produced by the conventional molding method. next,
Al foil with a thickness of 20 μm was used as the surface material 20 and 21, and polyester film adhesive (with a thickness of
30 μm), and was bonded to the core material under heat and pressure to form a diaphragm. The peel strength between the surface material and the core material at this time was 750 g. Further, a diaphragm was produced in the same manner using the core material 5 formed by the conventional core material cutting method, and the peel strength between the surface material and the core material was measured.
As a result, the peel strength was 150 g.

As described above, according to the present invention, it is possible to remove unnecessary parts of the core material, and to provide an adhesive margin for adhesion to the surface material. This makes it possible to provide a speaker with high performance and excellent reliability.

In addition, the pattern of the heartwood may be triangular, circular, rhombic, hexagonal, oval, etc., in addition to the examples, and various ways of arranging it may be considered, such as concentric, radial, etc., and the same effect can be obtained in any case. It is something.
Furthermore, the size of the diaphragm can be applied to larger squawkers and woofers other than those of the embodiments.

[Brief explanation of the drawing]

FIG. 1 is a process diagram for explaining a conventional method for manufacturing a diaphragm for a speaker, FIG. 2 is a process diagram for explaining an embodiment of the method for manufacturing a diaphragm for a speaker according to the present invention, and FIG. is a plan view of a molding die used in the same method. 11... Thermoplastic resin film, 12... Molding mold, 13... Suction hole, 14... First mold, 15
... Through hole, 16 ... Second mold, 17 ... Two-stage recess, 19 ... Core material, 20, 21 ... Surface material.

Claims (1)

[Claims] 1. A first mold having an uneven pattern and suction holes at the bottom of the recess, and a second mold having the same pattern as the first mold but with through holes wider than the recess pattern of the first mold. A molding die is provided which overlaps the mold and has two recesses as a whole, and a thermoplastic resin film is vacuum-, pressure- or vacuum-pressure-formed using this molding die to form a core material having a large number of unevenness, and then, Taking out the second mold along with the molded film core material, cutting and removing the convex portion of the film core protruding from the second mold, leaving a portion parallel to the surface material as a core material;
A method for manufacturing a speaker diaphragm, which comprises: thereafter bonding surface materials to both sides of the core material.