JPS5961296A - Manufacture of speaker diaphragm with edge formed in one body - Google Patents

Abstract

PURPOSE:To obtain a highly productive diaphragm omitting processes such as the forming of an edge and adhesion between the diaphragm and the edge part by forming the edge part in one body simultanoeously with the adhesion between the core of the diaphragm and a surface. CONSTITUTION:A formed sheet 1 is cut off larger than a surface sheet by the edge part and the surface sheet 4 is welded to both sides of the foamed sheet 2 with prescribed thickness at about 140-160 deg.C by thermally press-contacting. The peripheral part 3 of the foamed sheet 2 is formed as the edge. The characteristics of the diaphragm part formed by said procedure are extremely superior, and since the edge part is consisted of a foamed polypropylene, the part is light- weighted and has a high braking effect and fine speaker characteristics. Since the diaphragm and the edge are simultaneously formed, the process is simplified and the effect of a massproduction is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of manufacturing a diaphragm for a speaker that is integrally molded with an edge. By molding the outer peripheral portion as an edge, a manufacturing method with excellent mass production efficiency is provided that forms a lightweight and highly rigid diaphragm and a lightweight edge that is highly flexible.

In general, a speaker diaphragm is required to be lightweight and have a large Young's modulus (F;) and internal loss (tan δ), and edges are required to be lightweight, flexible, and have a large damping effect.

In recent years, the output of speakers has been increasing, and as a result, highly rigid and lightweight diaphragms are required.
Aluminum lamino two-cam diaphragms have been developed and have achieved this objective to some extent. However, these have drawbacks such as low internal loss and a complicated speaker assembly process. In addition, it is common to use cloth impregnated with a molding resin, coated with a damping agent, or molded with foamed resin and adhered to the diaphragm.

We have already proposed a speaker diaphragm characterized by heat-sealing a skin on both sides of a foam sheet in Japanese Patent Application No. 57-12]9]8, which is lightweight, has high rigidity, and has a moderate internal loss. Molded products K I, xi bonded with adhesives such as ayu, EBOKI 7 resin, urethane resin, etc.
It has excellent characteristics that are not seen in other countries.

The present invention is an improvement of the invention described in I-, and the edge portion is integrally molded at the same time as the diaphragm core and the outer skin are bonded together, thereby improving productivity by omitting processes such as forming the edge and bonding the diaphragm and the edge. We have developed a diaphragm with excellent performance.

The advantages of the method of the present invention are (1) there are fewer steps because the edges are formed at the same time as the diaphragm core material and the outer skin are thermally fused, and (2) there is no need for adhesives to bond the edges and the diaphragm. (3) The configuration is simple because the diaphragm core material is used as an edge material.

Next, one embodiment of the present invention will be described.

70 parts by weight of copolymer polypropylene, 25 parts by weight of graphite powder and 5 parts by weight of mica powder are kneaded, and 0.2 m
Sheeting is performed to a thickness of m to obtain a sheet for the epidermis. The characteristics of this note are ρ: 1.05E: 6.3X]0
10dyne/cm2. than δ: 8x1n-2, heat distortion temperature is 150-160°C9 melting point is 165
~180°C.

Next, copolymer foamed polypropylene/-to (e.g. foaming ratio 10 to 15 times, closed cell sheet thickness 1 due to foaming agent)
~3mm). The heat distortion temperature of this sheet is 1
15-130°C1 melting point is 140-160°C.

In Fig. 1, the foam sheet (1) is cut at the edges to be larger than the skin sheet, and the skin sheet (4) is placed on both sides of the foam sheet 1-(2) of the diaphragm portion by 140 to 1
It is fused by thermocompression to a predetermined thickness at a temperature of 60°C. At the same time as the trench, the peripheral portion (3) of the foam sheet is formed as an edge.

The characteristics of the diaphragm part formed in this way are =0.25, V when using a foam sheet of 2 mm.
Fi//'==2.3X 1 (15dyne/cm2.
It showed a value of t, en δ = 8 x 10'', and was very excellent as a diaphragm material.Since it is made of black and the edge portion is made of foamed polypropylene, it is lightweight, has a large damping effect, and has good speaker characteristics.

As explained above, the manufacturing method of the present invention not only provides good speaker characteristics, but also simplifies the process because the perturbation plate and the process are molded at the same time, and the breeding effect is excellent.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of the rib part of an embodiment of the present invention. (4) is the skin part of the diaphragm.

Claims (3)

[Claims] (1) In the manufacturing method of a diaphragm in which a foam sheet and a skin are heat-sealed and molded, a foam sheet serving as a core material is extended beyond the skin, and the foam sheet is integrally molded as an edge part. Production method. (2) The core material of the diaphragm and the outer skin are heat-sealed, and the diaphragm core material and the skin are heat-sealed, with edges remaining on both sides of the foamed channels that become the edges. 1) The method for manufacturing a speaker diaphragm described in section 1). (3) - The epidermis is mainly composed of polypropylene,
Kashinei manufactures diaphragms for speakers.