JPH0440799A - Production of diaphragm for speaker - Google Patents

Abstract

PURPOSE:To form a high performance diaphragm with an extremely high E/rho value by forming the diaphragm with filling ceramics and so on within clearance to exist in a coating film or within the clearance to exist in the coating film after the coating film is calcined after releasing the coating film from a die. CONSTITUTION:A diaphragm is formed by a first process to form a coating film 6 of ceramics and so on attached on a die 5 by plasma spraying, a second process to release the coating film 6 formed by the first process from the die 5 ad a fourth process to fill the ceramics or metal by a CVD method within clearance to exist in the coating film 6 formed by the second process or within the clearance to exist in the coating film 6 after being calcined by a third process to calcine the coating film 6 after being calcined by a third process to calcine the coating film 6 formed by the second process 2. Thus, the diaphragm with an extremely high comparative elastic modulus E/rho value is manufactured.f Besides, the E of the comparative elastic modulus represents a Young's modulus and the rho represents density.

Description

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

[Prior Art] Conventionally, speaker diaphragms have a specific elastic modulus E/ρ (E
: Young's modulus, ρ : density), that is, a large rigidity and light weight, is known to be desirable for acoustic properties, and for this reason, various studies have been conducted on the materials, shapes, and manufacturing methods of speaker diaphragms. has been done. Recently, ceramics having a relatively large E/ρ value compared to metals such as aluminum and titanium have been used for speaker diaphragms.

FIG. 5 is a schematic diagram for explaining the steps of a conventional method for manufacturing a speaker diaphragm using ceramics. In the figure, (A) is a plasma spraying process, (B) is a mold release process, and (D) is a baking process.

In each of these steps (A), (B), and (D),
1 is a thermal spray gun, 2 is a powder supply nozzle, 3 is a thermal spray powder,
4 is a plasma flame, 5 is a mold having a desired shape such as a dome shape, 6 is a film that becomes a diaphragm, 7 is a container such as an electric furnace, 8
9 is a heater such as a resistance wire, 9 is an exhaust port with a valve, and 10 is an inlet with a valve for introducing inert gas.

Next, a method of manufacturing the conventional speaker diaphragm will be described. First, in the plasma spraying process (A), a high-temperature, high-speed plasma flame 4 is generated by emitting a mixed gas of argon (Ar) and hydrogen (H) or nitrogen (N) and hydrogen (H) from a thermal spray gun 1. Powder 3 of ceramics such as boron carbide (BaC) is introduced into the center of the chamber from a powder supply nozzle 2 while being placed on argon or nitrogen for transportation.

Then, the injected thermal spraying powder 3 is melted, and this molten thermal spraying powder 3 adheres to the surface of a mold 5 having a desired shape such as a dome shape, which is placed in front of the plasma flame 4.
A film 6 that becomes a diaphragm is formed. Next, the mold release process (B
), the skin M6 is separated from the mold 5, and a film 6 made of ceramic alone is created. Subsequently, in the firing step (D), the film 6 is placed in a container 7 such as an electric furnace, and fired at about 200° C. with a heater 8 in a vacuum or in an inert gas. Thereby, a diaphragm with a high E/ρ value can be obtained.

[Problems to be Solved by the Invention] The conventional speaker vibration described above is produced by the manufacturing method described above, and for this purpose, a diaphragm made of metal such as titanium/aluminum (TI-A1) and a In comparison, a diaphragm with a significantly higher E/ρ value was obtained. However, in the diaphragm manufactured by the conventional manufacturing method as described above, even after the film 6 that becomes the diaphragm is fired in the firing process (D), the diaphragm has a content close to about 17%. There is a void. This fact is
This has been proven by the experimental results of test research conducted by the applicant of the present invention. Therefore, in the conventional manufacturing method of a speaker diaphragm, a diaphragm is created in which about 17% of the voids exist in the diaphragm made of the skin 116, as described above, and there are few voids. In addition, there was a problem in that it was extremely difficult to create a diaphragm having an even higher E/ρ value.

This invention was made in order to solve the above-mentioned problems, and it is a speaker diaphragm that has an extremely high E/ρ value and can create a diaphragm that is optimal for higher performance speakers. The purpose is to obtain a manufacturing method.

[Means for Solving the Problems] A method for manufacturing a speaker diaphragm according to the present invention involves forming a film of ceramics or the like on a mold having a desired shape by plasma spraying, and then releasing the film from the mold. CV
The diaphragm is made by filling ceramics or metal using the D method.

[Function] The method for manufacturing a speaker diaphragm according to the present invention includes a first step of forming a film of ceramics or the like on a mold by plasma spraying, and a film formed by this first step. A second step of releasing the film from the mold, and a third step of firing the film formed in the second step or in the voids existing in the film formed in the second step. Since the diaphragm is created through the fourth step of filling ceramics or metal into the voids existing in the film using the CVD method, it is possible to manufacture a diaphragm with an extremely high E/ρ value. I can do it.

[Example] FIG. 1 is a schematic diagram for explaining the steps of a method for manufacturing a speaker diaphragm according to an example of the present invention. In the figure, (A) is a plasma spraying process, (B) is a mold release process,
(C) is a CVD (chemical vapor deposition) process, and (D) is a firing process. Each of these steps (A), (B), (C),
In (D), 1 is a thermal spray gun, 2 is a powder supply nozzle, 3 is a thermal spray powder, 4 is a plasma flame, 5 is a mold having a desired shape such as a dome shape, 6 is a coating that becomes a diaphragm, and 7 is a A container such as an electric furnace, 8 a heater such as a resistance wire, 9 an exhaust port with a valve, 10 an inlet port with a valve for introducing inert gas, 11 a CVD (chemical vapor deposition) device container, and 12 a susceptor. Carbon, 13 is a high frequency coil for induction heating, 14 is CVD raw material gas, 15 is CVD raw material gas 14
16 is a gas exhaust port for the CVD source gas 14.

Next, a method of manufacturing a speaker diaphragm according to an embodiment of the present invention will be described. Similar to the conventional manufacturing method shown in FIG.
00° C.), a thermal spraying powder 3 of ceramics such as boron carbide having an average particle size of 20 μm is introduced into the center of the high-speed plasma flame 4 from the powder supply nozzle 2 while being carried by argon or nitrogen. Then, the injected thermal spray powder 3 melts or semi-melts in the plasma flame 4.
The coating 6 is deposited at high speed on the surface of a mold 5 having a desired shape, such as a dome shape, placed in front of the diaphragm, cooled, and deposited assimilated to form a film 6 that becomes a diaphragm. Subsequently, in the mold release step (B), by smoothing the surface of the mold 5 in advance and selecting an appropriate material, the film 6 formed as described above can be separated from the mold 5. As a result, a film 6 made of a single ceramic material such as boron carbide is formed. Since the film 6 thus formed has a structure in which most of the boron carbide particles are mechanically deposited, the bond between each particle is relatively weak and about 1
Since there are about 7% voids, the E/ρ value is relatively small.

Therefore, in this invention, the subsequent CVD step (C)
In this step, the above-mentioned voids existing in the film 6 are filled with ceramics by the CVD method.

Here, a method for filling voids in the film 6 with, for example, boron carbide will be described. First, the film 6 is placed in a CVD device container 11, and after the vacuum pump is used to evacuate the temperature to below about 10-'torr, the carbon 12 and the film 6 are heated to about 800°C to 1300°C by induction heating using the high-frequency coil 13. do. Next, gasified BCl3, co, and H are adjusted using a mass flow meter and sprayed onto the coat 6 as the CVD source gas 14 to the coat M6 thus heated. The blown CVD raw material gas 14 adheres to particles on the surface of the film 6, and also penetrates and accumulates in the voids of the film 6, gradually filling the voids (pores). Here, the exhaust gas inside the CVD device container 11 is
Processing continues. Furthermore, the structure of the coating 6 before the CVD treatment is characterized by the fact that the vicinity of the part that was in contact with the mold 5 is crushed and has fewer voids, which is a characteristic of thermal sprayed coatings.

For this purpose, it is more efficient to blow the CVD raw material gas 14 onto the film 6 in the direction in which there are many voids in the film 6, that is, in the direction shown in the CVD step (C) in FIG. 1, to fill the voids. be able to. On the contrary, if the CVD raw material gas 14 is sprayed onto the film 6 from the direction of the part that was in contact with the mold 5, the voids in the film 6 will quickly become clogged, making it extremely difficult to fill the voids throughout the film 6. become. In this example, approximately 70% of the voids existing in the coating 6 could be filled with boron carbide (B a C).

Next, after the voids in the film 6 are filled with boron carbide,
Furthermore, the film 6 is fired in a firing step (D). This firing is performed by placing the film 6 in a container 7 such as an electric furnace, and placing the film 6 in a vacuum with the inside of the container 7 evacuated or in an atmosphere containing an inert gas such as argon or nitrogen after evacuation. Perform firing. The degree of sintering of the film 6 in this case varies depending on the firing temperature, and the E/ρ value gradually increases from about 1000°C to a peak value at about 2100°C.

2 and 3 are schematic diagrams for explaining the steps of a method for manufacturing a speaker diaphragm according to another embodiment of the present invention, and the same reference numerals as in FIG. 1 indicate the same or equivalent parts. Therefore, detailed explanation thereof will be omitted.

In the manufacturing method of another embodiment of the present invention shown in FIG. 2, the steps up to the plasma spraying step (A) and the 51 type step (B) are the same as the manufacturing method shown in FIG. In the case of the example, the firing step (D) is performed after the mold is released from the mold 5 in the mold releasing step (B). That is, with the film 6 placed in the container 7, the film 6 is fired at a high temperature in a vacuum or in an inert gas such as argon or nitrogen in the firing step (D), and the boron carbide (B4C) of the film 6 is heated. Increases the bonding force of particle nucleons. The film 6 treated in this manner has increased bonding between particles and has a few open pores compared to the film 6 before firing. However, the film 6 still has many voids, which are open pores. Therefore, as described above, the film 6 is then subjected to the CVD process (C).
Fill the voids with boron carbide (B a C). As a result, approximately 60% of the voids in the film 6 are filled with boron carbide (
84C), and the E/ρ value also changed from the above firing process (
D) can improve the performance by about 10% or more compared to just firing.

In addition, in the manufacturing method of another embodiment of the present invention shown in FIG. 3, each step (A) of the embodiment shown in FIG.
After processing in (B), (D), and (C),
This manufacturing method further includes a firing step (D).

FIG. 4 is a diagram showing a comparison of the E/ρ values of the coatings in the method of manufacturing a speaker diaphragm according to the conventional example and each embodiment of the present invention. Here, the film 6 in the firing step (D)
The firing is performed at a firing temperature of approximately 2000℃ in an argon atmosphere.
The figure shows the case of firing.

In addition, although the above-mentioned example shows the case where boron carbide (84C) is filled into the voids of the coating 6 by the CVD method, the material to be filled is preferably a material with a high E/ρ value, and in the case of ceramics, SiC is used.

S 13Na, T i C, C, etc. are suitable, and metals such as Be, Ti, etc. are suitable. And 5iC
As a raw material by OCVD method, S i c 1m+c3
H6 is used, and the temperature of the substrate is approximately 1000°C to 1500°C.
℃ is preferable. In addition, BCl3+H2 is used as the raw material for the CVD method of B, and the temperature of the substrate is approximately 500℃~
1500°C is desirable.

[Effects of the Invention] As described above, according to the method of manufacturing a speaker diaphragm of the present invention, a ceramic film is formed on a mold having a desired shape by plasma spraying, and this film is separated from the mold. After molding, the diaphragm is made by filling the voids in the film, or the voids in the film after firing the film in vacuum or in an inert gas, with ceramics or metal using the CVD method. Since I created it, E/ρ
The value is extremely high, and it has the excellent effect of making it possible to create a diaphragm that is optimal for use in even higher performance speakers.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram for explaining the steps of a method for manufacturing a speaker diaphragm according to an embodiment of the present invention, and FIGS.
The figure is a schematic diagram for explaining the steps of a method for manufacturing a speaker diaphragm according to another embodiment of the present invention, and FIG. 4 is a conventional example and a method for manufacturing a speaker diaphragm according to each embodiment of the present invention. FIG. 5 is a diagram showing a comparison of the E/ρ values of the films in FIG. In the figure, 1... Thermal spray gun, 2... Powder supply nozzle, 3... Thermal spray powder, 4-... Plasma flame, 5...
・Mold, 6... Film, 7... Container, 8... Heater, 9... Exhaust port, 1O... Inlet port, 11... CV
D (Chemical vapor deposition) equipment container, 12... Carbon, 13
...High frequency coil, 14...CVD raw material gas, 15
...-Gas inlet, 16...Gas exhaust port, (A)
...Plasma spraying process, (B)...-Mold release process, (
C)...CVD (Chemical Vapor Deposition) process, (D)...
This is the firing process. In addition, the same symbols in the figures indicate the same or equivalent parts.

Claims (1)

[Claims] A film of boron carbide or the like is formed on a mold having a desired shape by plasma spraying, and after this film is released from the mold,
The diaphragm is made by filling ceramics or metals by CVD (chemical vapor deposition) into the voids existing in the film, or into the voids existing in the film after firing this film in vacuum or inert gas. A method for manufacturing a speaker diaphragm, the method comprising: producing a speaker diaphragm;