JPS60109998A - Manufacture of diaphragm for speaker - Google Patents

Abstract

PURPOSE:To improve the performance of mold release of a composite by forming the composite through the forming of a B4C thermal spray film made of powder not coated with Ni to a mold frame and then plasma thermal spray of the thermal spray powder made of the B4C powder coated with Ni. CONSTITUTION:The B4C thermal spray powder not coated with Ni is applied with plasma thermal spray to the mold frame 4 of the speaker diaphragm so as to form the B4C thermal spray film 6a. Plasma thermal spray of the thermal spray powder coated with Ni to the B4C powder is applied to the thermal spray film 6a so as to form the composite used for the diaphragm for speaker. The speaker diaphragm 6 is obtained by releasing the composite 6 from the mold frame 4.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a method of manufacturing a diaphragm for a speaker.

[Prior art]

Higher specific modulus (vp) for speaker diaphragms
It is desirable to have both an appropriate amount of internal loss (η). Therefore, as a diaphragm that satisfies this characteristic, metals such as tool steel, TI, etc., or aluminum having the desired shape are used.
On top of a ceramic mold such as 2O5, BN, B
Some products are manufactured by plasma spraying ceramics such as 2O or Al2O5 to form a thin plate, then releasing the thin plate from the mold, and subjecting it to post-treatments such as resin impregnation as necessary.

Figure 1 is a block diagram showing the general manufacturing process of this diaphragm. First, there is a process of thermally spraying ceramics onto a mold rod. Next, a process of releasing the thin plate formed by thermal spraying from a mold, and a post-processing process. It's getting better.

Figure 2 is a cross-sectional view showing an example of a general manufacturing equipment for diaphragms (sprayed film), which basically consists of a thermal spraying device, a thermal spraying powder supply device, a thermal spraying powder, and a non-metallic material having a desired shape. Alternatively, it is constructed from a formwork made of ceramics. In the figure,
(1) is a plasma spraying device with an electrode (1a) and a nozzle (
During 1b), a mixed gas (1c) consisting of N2 or Ar gas mixed with an appropriate amount of H2 gas is introduced, and electric power is applied between the electrode (1a) and the nozzle (1b).

This mixed gas is ionized to generate a plasma flame (1d).゛The temperature of this plasma flame (1d) is about 20. Q O0
℃, and the flow velocity reaches approximately 3.000 m/sec,
Thermal spraying powder supply device (2) into this plasma flame (1d)
Supply pipe C! When thermal spraying powder (3) of ceramics (for example, B4C!), which is usually in the form of powder, is introduced from υ, it easily melts, collides with the formwork (4) having the desired shape at high speed, adheres and accumulates, and forms a thin plate. It is possible to form a thermal sprayed film (5) of. The sprayed film (5) after thermal spraying is attached to the outer formwork (4) as shown in the cross-sectional view of FIG. 3(a), but the tool steel,
If the surface of the formwork (4) made of hard metal such as T1 or ceramics is smooth, it can be easily removed by ultrasonic cleaning, as shown in Figure 3 (b).
An imaging plate (5) made of ceramic alone as shown in the cross-sectional view is obtained. In addition, a diaphragm made of this ceramic alone (5
) may be impregnated with resin or plated with gold or the like depending on the purpose, such as increasing mechanical strength.

Now, as shown in the cross-sectional view of Fig. 4, a general thermal spray powder supply device (2) has a hopper aa for storing the thermal spray powder (3) and a groove for scraping out the thermal spray powder (3). It is composed of a drum (2) that rotates at an appropriate rotational speed, a carrier gas made of argon or nitrogen, and an introduction pipe (c) through which thermal spraying powder (3) passes. The introduction pipe (c) is 8
It is connected to the supply pipe clυ shown in Figure 1. In this device, thermal spray powder (3
) is supplied to the inlet pipe as the drum (c) rotates.

Supply pipe CI on carrier gas 04! It is ejected from υ and used for thermal spraying. Therefore, in order to stably eject the thermal spraying powder (3), it is necessary that the thermal spraying powder (3) has good fluidity.

However, the conventionally used B4, which is available at a relatively low price,
0 Thermal spray powder is originally intended for abrasive materials.

The individual powders were angular, the fluidity of the powder was poor, and uneven supply occurred, making stable powder supply impossible, making stable thermal spraying impossible. the result.

Thermal spraying efficiency is poor, and if a large amount of powder is temporarily supplied, unmelted powder will be sprayed. Most of this unmelted powder scatters without adhering or bonding, reducing thermal spraying efficiency. Furthermore, some of the unmelted powder mixed in and adhered to the molten powder, resulting in a non-uniform sprayed film. This type of sprayed film has a low TVp of 1
Bonds between particles are weak (.

The mechanical strength was also weak, making it unsuitable for use as a speaker diaphragm.

Therefore, in order to increase thermal spraying efficiency and obtain a diaphragm with high VP and high mechanical strength, it has been considered to thermally spray a thermal spray powder in which metals such as Ni and copper are attached to the surface of ceramic powder such as oxides and carbides. It is being

Specifically, similar to the conventional example, a thermal spraying powder such as B4C powder coated with N1 is placed on a mold with a smooth surface made of metal or ceramics and having a desired shape (dome shape in the figure). Form a thin film by plasma spraying. This thermal spraying powder is coated with lJi, so B4C
The angularity of the powder is reduced, the fluidity of the powder is improved, stable supply is possible, and thermal spraying efficiency is increased. Also, due to the presence of N1 film on the surface of B4C.

This powder for thermal spraying causes a eutectic reaction when melted, lowering the melting point of the 121 surface and reducing the calorific power ζ required for melting. Furthermore, while the bonding of particles in the conventional diaphragm using a thermal spraying powder made of only B40 is a bond between B4O and B4C, in the diaphragm using this thermal spraying powder, B40
Because of N1 on the surface, N1-Ni or N1-B4O
It becomes a combination of As a result, the bonding strength of the entire membrane is strengthened.
A thin plate with excellent mechanical strength and Vρ can be obtained. However, the bond between the sprayed film and the formwork naturally becomes stronger.

As a result, the mold releasability deteriorates, the diaphragm (sprayed film) is easily damaged during mold release, and the number of times the mold can be used is also reduced.

[Summary of the invention]

This invention was made in order to eliminate the above-mentioned drawbacks of the conventional products, and was made by plasma-spraying B40 thermal spray powder, which is not coated with N1, onto the formwork of a speaker diaphragm.
A step of forming a C sprayed film and plasma spraying a thermal spraying powder of B40 powder coated with N to form a composite plate used as a speaker diaphragm, and removing the composite plate from the formwork. By applying a mold release process, the composite board has excellent mold release properties.

The object of the present invention is to provide a high-performance speaker diaphragm with high mechanical strength and specific modulus (K/4).

[Embodiments of the invention]

An embodiment of this invention will be described below. first.

B4C thermal spray powder not coated with Ni is plasma sprayed onto a formwork (41) having the desired shape (dome m in this case) shown in FIG. 5(a) to form the entire speaker diaphragm. B4C sprayed film with a thickness of 15 μm (about 10 inches of
6a) was formed. Next, thermal spray powder coated with N1 was similarly sprayed onto the B4C thermal sprayed film (6a) to a thickness of 135 μm.
A composite plate +61 was obtained by forming a B40# film (6b) covering a town of m. Thereafter, the composite plate +61 was released from the mold 141 to obtain a speaker diaphragm (6) shown in FIG. 5(b). This mold release was easily performed.

If the thickness of the B4C sprayed film (6a) is made too thin, it will not contribute to improving the mold releasability, so it is desirable that the thickness be at least 3 inches thicker than the thickness of the diaphragm. On the other hand, if the thickness is too large, the thermal spraying efficiency in manufacturing the diaphragm will deteriorate, and the mechanical strength and internal loss (IVp) of the diaphragm will decrease.
A value of 0 or less is desirable. Considering the overall characteristics, a thickness of about 10% of the thickness of the diaphragm is most preferable, and for a diaphragm with a thickness of 150 μm, a thickness of 10 to 15 μm was optimal.

In addition, the amount of Ni deposited in the B4C thermal spraying powder coated with Ni is determined by the thermal spraying efficiency, the mechanical strength of the diaphragm, and the specific elastic modulus (V
p) and internal loss (η). In other words, if the amount of N1 attached is too small, it will not be effective. +2 or more is desirable for B4C, and if the amount of Ni is too large, the overall ≠ will decrease, so the amount of Ni should be 30
It was desirable that the amount was less than % by weight.

If the diaphragm is manufactured using this method, the B4C sprayed film (6a) that is in direct contact with the formwork (4) will have a weak bonding force with the formwork (4) because it is made of B40 alone. A composite plate (6) formed by thermally spraying a thermal spray powder coated with N1 onto a membrane (6a) can be easily released from a mold (41) to produce a diaphragm. The majority of N
1 coated with B4C, it has high thermal spraying efficiency as well as mechanical strength and Jl! It has a high i/p.

〔Effect of the invention〕

As described above, according to the present invention, a B4C thermal spraying powder not coated with N1 is plasma-sprayed onto a formwork of a speaker diaphragm to form a B4C thermal spraying film, and the B4C powder is coated with N1 on this thermal spraying film. By performing a step of plasma spraying the coated thermal spray powder to form a composite plate used for a speaker diaphragm, and a step of releasing the composite plate from the mold,
The composite plate has excellent mold releasability.1 Mechanical strength and specific modulus (
The effect is that a high-performance speaker diaphragm with high □) can be obtained.

[Brief explanation of drawings]

Figure 1 is a block diagram showing the manufacturing process of a typical speaker diaphragm, Figure 2 is a sectional view showing an example of a typical manufacturing equipment, and Figure 3 (a) is before being released from a conventional mold. 3(b) is a sectional view showing the speaker diaphragm after release from the mold, FIG. 4 is a sectional view showing a general thermal spraying powder supply device, and FIG. 5 5(a) is a cross-sectional view showing a composite plate before being released from a mold according to an embodiment of the present invention, and FIG. 5(b) is a cross-sectional view showing a speaker diaphragm obtained after being released from the mold. In the figure, (1) is a thermal spraying device, (1a) is an electrode, (1
b) is a nozzle, (1 is a mixed gas, (1a) is a plasma flame, 12+ is a powder supply device for thermal spraying, Cl1l is a supply pipe, C
! are the hopper, (c) is the drum, cIO is the carrier gas, and @ is the introduction pipe. (3) is powder for thermal spraying, (4) is formwork, (6) is composite plate (
speaker diaphragm), (6a) is B4C sprayed film,
(6b) is a B4C sprayed film coated with N1. In Figure 1, the same reference numerals indicate the same or equivalent parts 0 Agent Masuo Oiwa Figure 1 Figure 2 Figure 4 Figure 5

Claims (1)

[Claims] B40 without N1 coating on the formwork of the speaker diaphragm
Plasma spray the thermal spraying powder to form a B4Cj thermal sprayed film,
A step of plasma spraying a thermal spray powder of B40 powder coated with N1 onto this thermal spray film to form a composite plate for use as a diaphragm for a speaker, and a step of releasing the composite plate from the mold for use in a speaker. Method of manufacturing a diaphragm.