JP4540415B2 - Method for manufacturing acoustic matching member - Google Patents

Description

The present invention relates to the production how the acoustic matching member of the ultrasonic flowmeter for measuring the flow rate, the flow velocity of the gas or liquid by utilizing ultrasonic waves (i.e., fluid).

  As an ultrasonic transducer used in a conventional ultrasonic flowmeter, a configuration including a piezoelectric body, a case, and an alignment member is disclosed (for example, see Patent Document 1). 5 and 6 are a cross-sectional view and a perspective view of an ultrasonic transducer used in the conventional ultrasonic flowmeter described in Patent Document 1. FIG. The ultrasonic vibrator 51 has a configuration in which a piezoelectric body 53 is covered with a case 52 and an acoustic matching member 54 is bonded to a top surface 52 a of the case 52.

The acoustic matching member 54 is composed of a hollow sphere and a mixture of binding materials surrounding the hollow sphere, and a configuration of an alignment member made of a resin material having a glass hollow sphere and bubbles inside is disclosed. (For example, refer to Patent Document 2). In addition, regarding a mold for molding this type of acoustic matching member 54, for example, Patent Document 3 discloses a mold having a structure for removing gas in a resin.
Japanese Patent Laid-Open No. 11-118550 Japanese Patent No. 2559144 JP 2003-236843 A

  However, since the conventional acoustic matching member described in Patent Document 2 contains many bubbles in the molded acoustic matching member, the density of the acoustic matching member is not stable. There is a problem that the performance is not stable.

  In addition, since the conventional molding method described in Patent Document 3 uses a press-shaped mold, when this method is used for molding an acoustic matching member, it is filled with hollow spheres that are easily damaged by pressure. The hollow sphere may be damaged. Therefore, this forming method is not suitable for use in forming the acoustic matching member, and it is necessary to remove the gas between the hollow spheres closely packed through the thick ceramic member. There is also a problem that it cannot be done.

The present invention is intended to solve the above problems, it is an object to provide a manufacturing how acoustic matching member capable of satisfactorily forming a stable acoustic matching member performance.

To achieve the above object, a manufacturing method of the acoustic matching member according to claim 1 of the present invention, the through-hole and smaller than the diameter gap portion of the opening dimension through hole from the through-hole periphery Ri connected to the through hole A step of disposing and holding a substantially cylindrical porous film on the inner wall surface of the through hole of the molding die provided on the outer periphery of the through hole, and a step of filling the hollow sphere in the film held by the molding die And supplying a binding material into the film filled with hollow spheres, and at the time of supplying the binding material, the film is sucked from the gap through the film while sucking the binding material while the inside of the mold is decompressed. And a step of curing the hollow sphere and the binding material to obtain a molded product for an acoustic matching member.

Moreover, the manufacturing method of the acoustic matching member of Claim 2 of this invention cuts, after taking out a molding from a film, and obtains an acoustic matching member.
Moreover, the manufacturing method of the acoustic matching member of Claim 3 of this invention takes out from the shaping | molding die with the film in which the molded object hardened | cured, cuts a molded object with a film, and obtains an acoustic matching member.

In the method for manufacturing an acoustic matching member according to the fourth aspect of the present invention, when the hollow sphere is filled in the film disposed in the mold, the mold is vibrated.
In the method for manufacturing an acoustic matching member according to claim 5 of the present invention, the film is obtained by coating a metal powder sintered body or a ceramic member, and the coating material has low adhesion to the binding material. Have sex.

In the method for manufacturing an acoustic matching member according to claim 6 of the present invention, the film is made of a fluororesin fiber .

By executing the manufacturing method according to any one of claims 1 to 6 , the hollow sphere can be finely filled without damaging the hollow sphere with pressure, and the hollow sphere is filled with the fine hollow sphere. The residual gas and the gas generated from the binding material can be quickly removed and the binding material can be sucked in while the binding material can be introduced into the mold to obtain a molded product in which the hollow spheres are closely and uniformly bonded. Is also possible. Moreover, since a film is hold | maintained by the inner wall face of a through-hole, the deformation | transformation can be suppressed and both the removal of gas and the favorable dimensional accuracy of a molded article can be made compatible.

Density above manner, according to the manufacturing method of the acoustic matching member of the present invention, even in the finely mold hollow spheres filled quickly can remove bubbles, hence acoustic matching member Is stabilized, and the performance of the ultrasonic transducer can be stabilized.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
(Embodiment 1)
1 (a) and 1 (b) show a plan sectional view and a front sectional view of a mold used for the acoustic matching member manufacturing method according to Embodiment 1 of the present invention, which is divided into two in the longitudinal direction. FIG. 3 is a view schematically showing an apparatus for manufacturing an acoustic matching member, and FIG. 3 is a longitudinal sectional view showing a state in which a molded product of the acoustic matching member is taken out from a mold.

  A molding die 1 for molding an acoustic matching member shown in FIGS. 1A and 1B is a brass material coated with a fluororesin, but can be used as a material for the molding die 1. Anything can be used, and not limited to this. Further, a through-hole 2 penetrating vertically is formed inside the mold 1, and an inner wall surface (an inner wall holding portion to be described later) of the through-hole 2 is not necessarily required but is subjected to a mold release process. Is preferred. The through-hole 2 has substantially the same shape as the outer shape of the molded product 4, and a through-hole is formed on the outer peripheral side of the through-hole 2 with a gap portion 3 including a groove portion having a semicircular cross section connected to the through-hole 2. Two or more are provided at equal intervals or non-uniform intervals with respect to the outer periphery of 2. In this embodiment, the through hole 2 is provided only at one central portion in the mold 1. However, the through hole 2 penetrating in the vertical direction in the mold 1 is provided at a plurality of positions. It may be provided.

  The inner wall surface of the through hole 2 in the mold 1 is covered with a substantially cylindrical film 5, and the film 5 is filled with a large number of hollow spheres 7 and a bonding material 9 for bonding the hollow spheres 7 to each other. (FIGS. 1A and 1B show a state in which the hollow sphere 7 and the binding material 9 are filled). This film 5 is formed by extending the fluororesin fiber so that the molten resin as the binding material 9 does not pass through, and is formed in a substantially cylindrical shape whose inner shape is the outer shape of the molded product 4. Is configured to be held along the inner wall holding portion 2 a of the through hole 2. The film 5 has a thickness of 20 μm to 1 mm. However, the material and the thickness are not limited as long as air permeability, low adhesion to the bonding material 9 and strength are ensured. A ceramic member or a metal powder sintered body may be obtained by subjecting a low adhesion coating material to a release coating treatment.

  The hollow sphere 7 is a hollow glass having a hollow structure and has a particle diameter of 10 μm to 150 μm. However, the material and the particle diameter are not limited as long as the hollow sphere 7 has a hollow structure. In this embodiment, a two-component epoxy resin is used as the bonding material 9. However, the material is not limited to this as long as the material can be bonded.

  When manufacturing the molded product 4 that is the basis of the acoustic matching member using the molding die 1, first, the filter 6 is installed on the lower surface of the molding die 1 and the molding including the bottom surface of the through hole 2 is performed. After covering the lower surface side of the mold 1, the hollow sphere 7 is finely filled in the space surrounded by the film 5, and then the filter 8 is also installed on the upper surface of the mold 1 (see FIG. 2). At this time, in order to finely fill the hollow spheres 7 into the film 5 held in the through holes 2, the hollow spheres 7 are filled while the mold 1 is placed on a vibration device and vibrated. Of course, the method is not limited to this method as long as the hollow spheres 7 can be finely filled in the film 5 held in the through hole 1.

  Next, in order to impregnate the bonding material 9 into the through-hole 2, the suction blocks 10 and 11 are installed at the upper and lower ends of the mold 2 and provided in one suction block (for example, the lower suction block 11). The resin supply port 12 is connected to the container 13 containing the binding material 9. Similarly, a suction port 14 provided in the other suction block (for example, the upper suction block 10) is connected to a vacuum pump 15, and the bonding material 9 in the container 13 is sucked by the vacuum pump 15.

  If the viscosity of the bonding material 9 is lowered during suction, the fluidity becomes higher and the suction becomes easier. However, if the bonding material 9 is heated to a high temperature in order to reduce the viscosity, the generation of the gas 16 from the bonding material 9 increases. Since the bonding material 9 is cured, it is preferable that the bonding material 9 is sucked at a predetermined temperature at which the bonding material 9 is not cured or foamed and has a low viscosity, while having some fluidity. In the present embodiment, the bonding material 9 used was an epoxy resin having a curing condition of 80 ° C. × 2 hours and then 150 ° C. × 2 hours. Therefore, the bonding material 9 was sucked while being held at 60 ° C.

  Next, the suction blocks 10 and 11 are removed from the mold 1, the mold 1 is placed in a thermostat, and the mold 1 is heated to cure the bonding material 9. In the present embodiment, a thermostatic bath is used in the heat curing step, but the heating method is not limited as long as heat curing is possible, and the heat curing may be performed using heating wire or induction heating.

After the heat curing is completed, the mold 1 is cooled, and the molded product 4 in the mold 1 is taken out. The molded product 4 is cut into a predetermined thickness as it is to obtain the acoustic matching member 17.
In the present embodiment, the predetermined thickness is obtained by cutting the molded product 4. However, the thickness of the through hole 2 may be set to the thickness of one acoustic matching member 17, and in this case Can omit the cutting step.

According to such a configuration, the hollow sphere 7 can be finely filled without damaging the hollow sphere 7 with pressure, and the residual gas and the bonding material 9 in the mold 1 filled with the hollow sphere 7 finely can be obtained. The bonding material 9 can be sucked by quickly removing the gas 16 generated from the above, and the molded product 4 in which the hollow spheres 7 are finely and uniformly bonded can be obtained. Moreover, since the film 5 is hold | maintained by the inner-wall holding | maintenance part 2a provided in multiple numbers in the through-hole 2, the deformation | transformation can be suppressed and gas removal and the favorable dimensional accuracy of the molded article 4 can be made compatible. The molded product 4 having such a configuration is suitable as the acoustic matching member 17 used for the ultrasonic vibrator because the molded product 4 is densely filled with the hollow spheres 7 and has a stable density. Moreover, since the film 5 is easy to remove, it can be easily replaced when the air permeability and releasability deteriorate.
(Embodiment 2)
FIG. 4 is a diagram showing an acoustic matching member manufacturing process (a process of taking out the molded product 4) in the second embodiment of the present invention. Note that the same components as those in the first embodiment are denoted by the same reference numerals, and description thereof is omitted.

  In the second embodiment, similarly to the manufacturing method described in the first embodiment, the hollow sphere 7 is filled in the film 5 held by the inner wall holding portion 2a in the through hole 2 of the mold 1 and then bonded. The material 9 is sucked, and the hollow sphere 7 and the bonding material 9 are heated to cure the bonding material 9. However, in the second embodiment, after that, the film 5 and the molded product 4 are taken out from the mold 1 together, and then cut into a predetermined thickness while the film 2 and the molded product 4 remain attached. To obtain the acoustic matching member 17.

  In the second embodiment, the predetermined thickness is obtained by cutting the molded product 4, but the cutting process is omitted by setting the thickness of the through-hole 2 to the thickness of one acoustic matching member 17. Can do.

  According to such a configuration, since the film 5 partially supported by the inner wall holding portion 2a of the through hole 2 is extracted from the through hole 2 of the mold 1, for example, the through hole 2 is a straight cylinder without a drawing taper. In addition, the taken-out molded product 4 is not damaged, and polishing and surface treatment of the molded product 4 and the acoustic matching member 17 after the removal are not necessary. Therefore, labor and time in the manufacturing process can be reduced to a small extent, and the manufacturing cost can be reduced.

Method for producing acoustic matching member of the present invention not only can be used as a method for producing an internal uniform free of air bubbles in the acoustic matching member of the matching member, the molding method of a resin material containing a filler of fillers such as It can also be applied.

(A) And (b) is a plane sectional view and a front sectional view of a mold (those divided into two in the longitudinal direction) used in the manufacturing method of the acoustic matching member according to Embodiments 1 and 2 of the present invention. The figure which shows simply the manufacturing apparatus used for the manufacturing method of the acoustic matching member which concerns on Embodiment 1, 2 of this invention. The longitudinal cross-sectional view which shows a mode that the molded article of an acoustic matching member is taken out in the manufacturing method of the acoustic matching member which concerns on Embodiment 1 of this invention. The longitudinal cross-sectional view which shows a mode that the molded article of an acoustic matching member is taken out in the manufacturing method of the acoustic matching member which concerns on Embodiment 2 of this invention. A perspective view of a conventional ultrasonic transducer Cross-sectional view of the conventional ultrasonic transducer

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Mold 2 Through-hole 2a Inner wall holding | maintenance part (through-hole inner wall surface)
DESCRIPTION OF SYMBOLS 3 Cavity part 4 Molded product 5 Film 6, 8 Filter 7 Hollow sphere 9 Bonding material 10, 11 Suction block 12 Resin supply port 13 Container 14 Suction port 15 Vacuum pump 16 Gas 17 Acoustic matching member

Claims (6)

The through holes and the porous substantially cylindrical shape into the mold through-hole wall face of which is provided on the outer circumferential opening dimension is smaller than the diameter gap portion is the through hole of the through hole of the through hole periphery Ri connected to the through hole Arranging and holding the film;
Filling the hollow spheres in the film held by the mold; and
A bonding material is supplied into a film filled with hollow spheres, and when the bonding material is supplied, the bonding material is sucked into the film while sucking the bonding material in a state where the inside of the mold is decompressed through the film from the gap. Introducing the process;
And a step of curing the hollow sphere and the binding material to obtain a molded product for the acoustic matching member.   The method for producing an acoustic matching member according to claim 1, wherein the acoustic matching member is obtained by cutting after removing the molded product from the film.   The method for producing an acoustic matching member according to claim 1, wherein the molded product is taken out of the mold together with the cured film, and the molded product is cut together with the film to obtain an acoustic matching member.   The method for producing an acoustic matching member according to any one of claims 1 to 3, wherein the mold is vibrated when the hollow sphere is filled in the film disposed in the mold.   5. The film according to claim 1, wherein the film is obtained by coating a metal powder sintered body or a ceramic member, and the coating material has low adhesion to the binding material. The manufacturing method of the acoustic matching member of description.   The method for manufacturing an acoustic matching member according to any one of claims 1 to 4, wherein the film is made of a fluororesin fiber.

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