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JPH03245697

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DESCRIPTION JPH03245697
[0001]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a
method of manufacturing a diaphragm for a speaker. [Prior Art] FIGS. 4 and 5 are views showing
a method of manufacturing a diaphragm for a speaker disclosed in Japanese Patent Laid-Open
No. 60-1691, and FIG. 4 shows a film for forming a diaphragm. FIG. 5 is a cross-sectional view
showing a firing apparatus for the above coating. That is, the diaphragm is manufactured into a
film having, for example, a dome shape, using the plasma spraying apparatus (1) shown in FIG.
The plasma spraying apparatus (1) described above has an electrode (1a) and a nozzle (1b), and a
mixed gas (IC) in which an appropriate amount of hydrogen gas is mixed in nitrogen or argon gas
is introduced therebetween. Then, by applying electric power between the electrode (18) and the
nozzle (1b), the mixed gas is ionized to form a plasma flame. Since this plasma flame is high
temperature and high speed, it is melted if the powder for the elbow is put from the supply port
(3) into it, it is melted and collides with the mold (4) to adhere, cool, solidify A deposit (5) is
formed, which is released from the mould. The surface of the coating obtained in this way is a
smooth surface corresponding to the surface of the mold (4), as shown in FIGS. . On the other
hand, the surface B of the side of the thermal spray apparatus has a small amount of crushing,
and the surface has a surface condition with severe irregularities corresponding to the particle
size of the melted particles. And the as-sprayed film (5) in this state has relatively weak bonding
between powder particles and low mechanical strength, so it is an important property of the
diaphragm E / 板 (E: Young's modulus, ρ: density) Therefore, as shown in the partial enlarged
view of FIG. 2, the coating (5) after thermal spraying is put into, for example, a carbon cylinder
and fired at 1000 ° C. to 2300 ° C. in an argon gas atmosphere. By this treatment, the bonds
between the particles are greatly strengthened, and a diaphragm having a large E / p value can
be obtained. [Problems to be Solved by the Invention] In the conventional method of
manufacturing a diaphragm, the film (5) is released from the thermal spray state and fired to
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form a diaphragm. However, as shown in (1-1) of FIG. 1 and (2-1) of FIG. 2, in the coating (5) as
sprayed, the surface B surface on the opposite side of the mold (4) is extremely uneven. When
vibrated as a diaphragm, a crack is apt to be generated at the concave portion, and the crack
spreads from the sprout and can not withstand large amplitude. Further, as shown in FIG. 6, in
the dome-shaped diaphragm, it is necessary to wind the voice coil (9) at the rising portion of the
diaphragm, but the insulating film of the coil is broken at the edge when the surface is extremely
uneven. There were problems such as
The present invention has been made to solve the above-mentioned problems, and it is an object
of the present invention to manufacture a highly reliable speaker diaphragm with less occurrence
of cracks. [Means for Solving the Problems] In the method of manufacturing a diaphragm for a
speaker according to the present invention, after a ceramic is plasma sprayed to form a film of a
predetermined shape on a mold of a predetermined shape in which 1 surface is processed to be
smooth, The surface of this film is polished to a smooth surface, and thereafter, the film is
released, and the film is fired, for example, at 1000 ° C. to 2400 ° C. in an inert gas to form a
diaphragm. [Operation] Polishing the surface of the film in the present invention makes the
surface roughness of the film smooth, suppresses cracking and propagation, and strengthens the
bonding between the voice coil and the film, resulting in high performance and high
performance. A reliable speaker diaphragm can be obtained. 4 and 5 show an apparatus used in
the manufacturing method of the present invention, which is similar to the apparatus used in the
conventional manufacturing method. That is, a film having a predetermined shape is first
manufactured using the plasma spray apparatus (1) shown in FIG. 4 for manufacturing the
diaphragm of the present invention. The plasma spraying apparatus (1) has an electrode (1a) and
a nozzle (1b), and a mixed gas (1c) in which an appropriate amount of hydrogen gas is mixed in
nitrogen or argon gas is introduced therebetween. Then, by applying power between the
electrode and the nozzle, the mixed gas is ionized to form a plasma flame. Since this plasma flame
is high temperature and high speed, it is melted if B and C of average particle diameter 10
microns to 50 microns, which is the diaphragm material, are injected from the supply port (3)
into it and collide with the mold (4) Adhesion, cooling, solidifying and depositing to form a film
(5) of B4C. Specifically, the surface of the film formed using B and C powder having an average
particle diameter of 17 microns is melted because the surface B of the side of the thermal
spraying apparatus is crushed as shown in FIG. 2 (2-1). As a result of the measurement of the
roughness shown in (3-1) of FIG. 3, the ten-point average roughness Rz is a rough surface
condition of about 5 microns with asperities corresponding to the particle diameter of the B4C
particles. Therefore, in order to make this surface smooth, it is polished with # 320-600 Emily
abrasive paper. Although B4C particles are harder than the abrasives used in Emily abrasive
paper, the bonds between B4C particles in the sprayed coatings can be relatively weak and easily
smoothed. (2-2) of FIG. 2 is a partially enlarged view of the film of the present invention after
polishing. Further, (3-3) in FIG. 3 shows the measurement result of the surface roughness of the
film of the present invention when polished by # 400 Emily abrasive paper, and in this case, Rz
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was about 1 micron.
Also, instead of using abrasive paper, abrasive powder such as alumina, SIC, 5IO2, etc. could be
made smooth by spraying and blowing using compressed air. After polishing in this manner, the
surface removed from the mold (4), which was in contact with the mold (4), corresponds to the
surface roughness of the mold (4) in the same manner as in the prior art. Rz was 0.5 micron in
roughness as shown to (3-2) of. Although it is possible to polish the surface of the film (5) after
mold release, this film is fragile, so it is necessary to use a jig adapted to the shape. Otherwise, it
may be broken in the polishing process, and it is better to polish before release, yet the film (5)
after release has relatively weak bonding between powder particles and low mechanical strength,
so vibration An important property of the plate, E / ρ (E: Young's modulus, 重要: density) is also
small. Therefore, the film (5) after mold release was placed in a carbon cylinder (6) as shown in
FIG. 5 in a vacuum in a baking furnace (7) or in an inert atmosphere such as nitrogen or argon as
in the prior art It bakes at 1000 degreeC-2300 degreeC with a heat source (B) in a state. As a
result, the coupling between particles becomes significantly stronger and the E / ρ value
becomes thicker. FIG. 7 shows the relationship between the roughness Rz of the polished surface
B and the bending strength of the diaphragm in the case of firing at 2000 ° C. in an argon
atmosphere, and the bending strength of the strip-shaped sample is a dome-shaped diaphragm It
measures by three-point bending method about what was produced by the same method. As
apparent from this result, the smaller the surface roughness, the higher the bending strength.
The sample not polished (Rz about 5 microns) was 25 kg / m 2 or less, but the bending strength
increased as the surface became smooth by polishing, and the bending strength became about 30
kg / gIl + 1 when Rz became 1 micron. Since the bending strength increases as the surface
becomes smooth like this, it is better to make the strength smoother, but it is expensive, so it is
desirable to determine the degree of polishing depending on the purpose. Incidentally, since the
film after firing has a strong bond between B4C particles and the hardness of B4C particles is
large, polishing after firing is extremely difficult. Since the diaphragm of the present invention
manufactured in this manner has a smooth surface of the film, generation of cracks is small and
high amplitude vibration is possible. Also, the adhesion between the voice coil and the film
becomes good, and it becomes possible to add a high input, for example, the amplitude resistance
and the input resistance of the one whose surface is polished to have Rz of 1 micron compared to
the conventional non-polished diaphragm. Both increased by about 30%. Although the example
using B4C as the material of the diaphragm has been described in this embodiment, the same
effect can be obtained with other ceramics or a mixture of ceramics and metal.
[Effects of the Invention] In the present invention, after a ceramic is plasma-sprayed to form a
film on a mold having a predetermined shape whose surface is processed to be smooth as
described above, the surface of the film is polished smoothly, and then separated. Since this film
is molded and fired in an inert gas, there is an effect that a high-performance speaker diaphragm
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having a high reliability, a small number of cracks, and a high amplitude resistance and a large
input resistance can be obtained.
[0002]
Brief description of the drawings
[0003]
FIG. 1 shows the surface roughness of the film for diaphragms formed by the manufacturing
method of the present invention and the conventional manufacturing method, (1-1) is the
conventional one, and (1-2) is the one of the present invention It is.
FIG. 2 is a partial enlarged cross-sectional view showing the roughness of each of the abovementioned films, (2-1) is a conventional one, and (2-2) is one of the present invention. Fig. 3
shows measurement data of surface roughness before and after polishing, (3-1) before polishing
of surface B of Fig. 2, (3-3) after polishing, (3-2) Is measurement data of side A of FIG. FIG. 4 is a
cross-sectional view showing a conventional plasma spraying apparatus and a spraying state
according to the prior art and the present invention, FIG. 5 is a cross-sectional view likewise
showing a sintering apparatus, and FIG. FIG. 7 is a characteristic view showing the relationship
between the surface roughness of the diaphragm and the bending strength. In the figure, (4) is a
mold and (5) is a film. Fig. 1-1-2 Fig. 2m) 11) Bonds-3-2 Fig. Fig. Fig. Fig. 2 Fig. 3 3 Roughness Rz
of 48 (Procedure for correction of procedure (voluntary)
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