JP2000191824A - Production of underwater sound absorbing wedge - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a process for producing underwater sound absorbing wedges which can improve productivity and workability and reduce cost since processing molds are not required and, in addition, the elimination of the bonding step and the mass production of underwater sound absorbing wedges in any shape in the final cutting step are possible in producing the underwater sound absorbing wedges. SOLUTION: A process for producing underwater sound absorbing wedges comprises adding a predetermined amount of microballoons of the unexpanded type to a rubber compound, kneading the resulting mixture, then molding the kneaded product into a sheet, expanding the microballoons added to the rubber compound by the vulcanization heat in the vulcanization step of this sheet material in vulcanization molding to form cells within the sheet material, and cutting the resulting sheet material into the predetermined shape of a wedge in the cutting step.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing an underwater sound-absorbing wedge, and more particularly to a method for producing a flat underwater sound-absorbing wedge having pores therein efficiently and at a low cost. It relates to a manufacturing method.

[0002]

2. Description of the Related Art An underwater sound-absorbing wedge to be mounted on a wall surface of a water tank or the like for acoustic measurement has a plurality of pores (cavities) inside a flat wedge body made of a rubber-like viscoelastic material. Generally, the wedge body is arranged in parallel with a reflecting plate such as an iron plate via a mounting bracket. The pores contribute to changing the propagation velocity (C) inside the sound absorbing wedge.

By adjusting the propagation velocity (C) and the propagation constant (δ) determined by the elastic loss coefficient (η) of the rubber-like viscoelastic body and the density (ρ) of the sound absorbing wedge to appropriate values, It exhibits a reflection reducing effect.

[0004]

As shown in FIGS. 7 (a) and 7 (b), the underwater sound-absorbing wedge 1 is a plate-like base rubber 2 made of a rubber-like viscoelastic material. A concave portion 3 is formed on the side surface by a mold or the like, and a cover rubber sheet 4 is integrally adhered to the base rubber 2 via an adhesive or the like so as to seal the concave portion 3. Is a general manufacturing method.

However, such a manufacturing method requires a special processing mold for forming the concave portion 3 and a step of bonding two types of rubber parts (a base rubber and a cover rubber sheet). There was a problem that it was very difficult to reduce costs. In addition, there is a problem that by attaching the thin cover rubber sheet 4 to one side surface of the base rubber 2, a relatively thin underwater sound absorbing wedge tends to tilt in a certain direction.

An object of the present invention is to eliminate the need for a processing mold when manufacturing a sound-absorbing wedge, to omit the bonding step, and to realize mass production in an arbitrary shape by the final cutting step. It is an object of the present invention to provide a method for producing an underwater sound absorbing wedge that can improve workability and reduce costs.

[0007]

According to the present invention, in order to achieve the above object, a predetermined amount of an unfoamed microballoon is added to a rubber compound and kneaded, and after kneading the rubber compound, the rubber compound is processed into a sheet. When vulcanizing the sheet material in the vulcanizing step, the heat of vulcanization causes the microballoons added to the rubber compound to foam to form pores inside the sheet material, and the sheet material is subjected to a predetermined process in the cutting step. The gist is to cut into a wedge shape.

According to the present invention, a predetermined amount of a non-foamed type microballoon is added to a rubber compound in advance and kneaded, and the microballoon is foamed by utilizing the heat of the vulcanization step during vulcanization molding. By forming pores in the sound-absorbing wedge, a mold for producing pores is not required, and a bonding step of a cover rubber for sealing the pores can be omitted. By cutting the sound-absorbing wedge, mass production becomes possible, productivity and workability can be improved, and cost can be reduced.

[0009]

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a flowchart showing a process for producing a water-absorbing wedge of the present invention. In the embodiment of the present invention, a water-absorbing wedge is produced by the following steps.

That is, in FIG. 1, a kneading process (step) of a rubber compound mainly composed of chloroprene rubber is performed.
Then, a predetermined amount of unfoamed microballoons is added to the rubber compound (in this embodiment, the volume content is 10%
１５15%), and after kneading for a predetermined time, the rubber compound is sheeted out by a calender roll device or the like (step).

Next, the sheet material is continuously vulcanized and formed (step) in a vulcanization step. At the time of the vulcanization and molding, microballoons added to the rubber compound at a vulcanization temperature (around 150 ° C.). By foaming, as shown in FIGS. 2 and 3 (a) and (b), a number of minute (about 30 to 50 μ) pores Q are formed inside the sheet material.

Then, the sheet material thus formed is cut into a predetermined wedge shape by a cutter such as a cutter (step), and a water absorbing wedge W product is completed through a finishing step (step).

Examples of the non-foamed type microballoon include, for example, a microsphere manufactured by Matsumoto Yushi Co., Ltd.
F-82 is preferred. This F-82 is a heat-expandable microballoon which is microencapsulated with a shell wall of a copolymer such as vinylidene chloride and acrylonitrile and contains a low-boiling hydrocarbon.

[0014] The addition of microballoons is desirably 10 to 15% by volume content, and if it is too large, the acoustic performance will not be dramatically improved. Also, when a large amount is added, it becomes difficult to stabilize the thickness as a product.

The underwater sound-absorbing wedge W formed as described above
When used in a water tank for acoustic measurement, as shown in FIG. 2, it is fixed to an acoustic reflection plate 1 such as an iron plate via a fitting 2 or the like so as to be self-standing.

As described above, a predetermined amount of an unfoamed type microballoon is added to the rubber compound and foamed inside by the heat of vulcanization to form minute pores Q, thereby mainly providing a high frequency band in a high frequency band. It can exhibit a reflection reducing effect.

Next, as an embodiment of the present invention, the result of an experiment using the measuring jig of FIG. 4 will be described. FIG.
Is a measurement jig used in an acoustic measurement water tank or the like,
On the ladder 3, a transmitter 4 and a receiver 5 are hung at an interval of 50 cm, and an inner portion of the ladder 3 is attached to an acoustic reflection plate 1 such as an iron plate at a distance of 260 cm via a mounting bracket 2 at an interval of 260 cm. An underwater sound-absorbing wedge W having a large number of micropores Q is provided.

The underwater sound-absorbing wedge W, which is self-supporting on the acoustic reflector 1 via the mounting bracket 2, is attached to the acoustic reflector 1 at a predetermined interval in parallel and self-standing, as shown in FIG. In the measurement method of the reflection reduction effect amount in this experimental example, six underwater sound-absorbing wedges W were attached to an acoustic reflection plate 1 such as an iron plate at an interval of 75 mm, and measurement was performed using a measurement jig shown in FIG.

As is clear from the measurement results shown in FIG.
The sound-absorbing wedge containing micro-balloons with minute pores Q formed in the underwater sound-absorbing wedge W between 5 [KHz] and 20 [KHz] has an effect of reducing the reflection compared to the underwater sound-absorbing wedge made of rubber without microballoons. (ER) can be significantly increased.

The reflection reduction effect amount (ER) can be obtained by the following equation. ER [dB] = (TS of iron plate that can be regarded as perfect reflector)-
(TS when sound absorbing wedge is attached to iron plate) TS: Target strength

[0021]

According to the present invention, as described above, a predetermined amount of an unfoamed microballoon is added to a rubber compound and kneaded. After kneading the rubber compound, the rubber compound is processed into a sheet, and the sheet material is added. In the vulcanization step, the microballoons added to the rubber compound are foamed by the heat of vulcanization during vulcanization molding to form pores inside the sheet material, and the sheet material is cut into a predetermined wedge shape in the cutting step. Therefore, no processing mold is required during the production of the sound-absorbing wedge, the bonding process can be omitted, and the final cutting process enables mass production to any shape, improving productivity and workability. This has the effect that the cost can be reduced as well as the cost can be reduced.

[Brief description of the drawings]

FIG. 1 is a flow chart showing a process for producing an underwater sound absorbing wedge of the present invention.

FIG. 2 is a perspective view showing an attached state of the underwater sound absorbing wedge according to the present invention.

FIG. 3A is a front view of an underwater sound absorbing wedge according to the present invention, and FIG. 3B is a cross-sectional view taken along line XX of FIG.

FIG. 4 is an explanatory view of a measurement jig for measuring the reflection reduction effect amount (ER) of an underwater sound absorbing wedge used for acoustic measurement.

FIG. 5 is an enlarged side view taken along the line AA of FIG. 4;

6 is a graph illustrating the results of comparing the sound absorbing wedges with microballoons and the sound absorbing wedges without microballoons with the measurement jig of FIG.

FIG. 7 (a) is a front view of a conventional underwater sound absorbing wedge,
(B) is sectional drawing in the BB arrow line of (a) figure.

[Explanation of symbols]

Reference Signs List 1 acoustic reflection plate such as iron plate 2 mounting bracket 3 ladder 4 transmitter 5 receiver W underwater sound-absorbing wedge Q minute pore

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4F074 AA05 CB62 CB84 CC06Y CC22X CD08 DA57 4F201 AA45 AB02 AE07 AG01 AG20 AR15 BA03 BC01 BC12 BC17 BC37 BM12 BM14 4J002 AC001 EA006 FA106 FB206 FD326

Claims (2)

[Claims] 1. A non-foaming type microballoon is added to a rubber compound in a predetermined amount and kneaded, and the rubber compound is kneaded, processed into a sheet, and vulcanized and formed in a vulcanizing step of the sheet material. A method for producing an underwater sound-absorbing wedge in which microballoons added to the rubber compound are foamed by heat of vulcanization to form pores inside the sheet material, and the sheet material is cut into a predetermined wedge shape in a cutting step. 2. The method for producing an underwater sound-absorbing wedge according to claim 1, wherein an unfoamed microballoon is added to the rubber compound at a volume content of 10% to 15%.