Sonar Dome

Abstract

To provide a sonar dome made of FRP which is advantageous for improving durability by alleviating concentration of stress in a spot at a boundary of a core material and a dome body during high speed navigation.SOLUTION: A sonar dome 14 includes a bead unit 16 with a core material 22 and a dome body 18 extending from the bead unit 16. The dome body 18 is composed to include an FRP plate 26A. The FRP plate 26A is wound around the core material 22 and folded back at the bead unit 16. A gap sealing rubber 30A for sealing a gap S made of a hard rubber and vulcanization-molded in a sectional form with its thickness gradually reducing as it separates from the core material 22 is arranged in the gap S formed between the core material 22 and a position where the FRP plate 26A is folded back from the core material 22.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a sonar dome that covers a transducer installed on the bottom of a ship and protects the transducer from noise generated from the ship itself. [Background technology]

[0002] The sonar dome includes a bead portion having a core material and a dome body extending from the bead portion. The sonar dome is installed on the bottom of the ship by attaching the bead part to the hull. Such sonar domes are traditionally made from rubber. As a result, as ships have become faster in recent years, the stress acting on the sonar dome body when traveling at high speeds has increased, causing problems such as deformation of the dome body and increased resistance at the bottom of the ship. Therefore, the present inventors have proposed a sonar dome made of FRP that can prevent deformation during high-speed navigation, and this FRP sonar dome has a dome body that includes an FRP plate. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication 2012-111310 Summary of the Invention [Problem to be solved by the invention]

[0004] On the other hand, since the sonar dome is installed at the bottom of the ship by attaching the bead part to the hull, the FRP dome body needs to be connected by hanging the FRP plate on the core material at the bead part in order to strengthen the connection between the core material and the FRP plate. Here, the core material is configured to include a flexible wire, the cross section of the core material is circular, and the outer diameter of this circular core material is often formed to be larger than the thickness of the dome body. Therefore, when connecting an FRP plate to a core material, if the FRP plate is hung around the entire circumference of the core material, the FRP plate will be circular at the core material, and the part of the dome body adjacent to the core material will be a plate-like shape with a thickness smaller than the outer diameter of the core material, resulting in a point where the cross-sectional shape changes suddenly at the boundary between the core material and the dome body. Therefore, if the stress acting on the dome body of the sonar dome increases when a ship is traveling at high speed, stress will be concentrated at the boundary between the core material and the dome body when traveling at high speed, which is detrimental to improving the durability of the FRP sonar dome. The present invention was devised in consideration of the above-mentioned circumstances, and an object of the present invention is to provide a sonar dome made of FRP that is advantageous in reducing stress concentration at the boundary between the core material and the dome body during high-speed navigation and improving durability. [Means for solving the problem]

[0005] In order to achieve the above-mentioned object, one embodiment of the present invention is a sonar dome comprising a bead portion having a core material and attached to the hull side, and a dome body extending from the bead portion, wherein the dome body is constructed including an FRP plate, the FRP plate is hung on the core material at the bead portion and folded back, and a gap-closing rubber that is made of hard rubber and vulcanized to a cross-sectional shape whose thickness gradually decreases with distance from the core material is disposed in the gap formed between the core material and the point where the FRP plate is folded back from the core material, and that closes the gap. The gap-closing rubber is made of hard rubber and vulcanized to a cross-sectional shape whose thickness gradually decreases with distance from the core material. In one embodiment of the present invention, the gap blocking rubber has a core material joining surface joined to the outer peripheral surface of the core material, and a pair of FRP plate joining surfaces extending and slantingly approaching each other from both circumferential ends of the core material joining surface, and the FRP plate has a semi-cylindrical cylindrical surface portion hung on and joined to the core material, a pair of inclined surface portions connected to both circumferential ends of the cylindrical surface portion and joined to the pair of FRP plate joining surfaces and extending and approaching each other, and a dome body forming surface portion connected to ends of the pair of inclined surface portions and forming the dome body. In addition, one embodiment of the present invention is characterized in that the pair of FRP plate joining surfaces are formed by curved surfaces that displace in directions toward each other, and the pair of inclined surface portions are formed by curved surfaces that correspond to the curved surfaces. In one embodiment of the present invention, the pair of FRP plate joining surfaces intersect at ends remote from the core material. In one embodiment of the present invention, the pair of FRP plate joining surfaces face each other at a predetermined distance apart at ends remote from the core material. Effect of the Invention

[0006] According to one embodiment of the present invention, the dome body is constructed including an FRP plate and has greater rigidity than a conventional rubber dome body, which is advantageous in preventing deformation of the dome body even when subjected to large stress during high-speed navigation and in suppressing an increase in resistance at the bottom of the ship during high-speed navigation. In addition, in the gap formed between the core material and the point where the FRP plate is folded back from the core material, gap-closing rubber is placed, which is made of hard rubber and vulcanized to a cross-sectional shape whose thickness gradually decreases as it moves away from the core material.As a result, the cross-sectional shape of the two FRP plates folded back by the core material and facing each other changes gradually, without a sudden change at the boundary between the bead portion and the dome body. Therefore, even if the stress acting on the dome body increases when a ship is traveling at high speed, stress concentration in the FRP plate at the boundary between the bead portion and the dome body can be suppressed, which is advantageous in improving the durability of the sonar dome. In addition, the use of gap-blocking rubber is advantageous in that it enables the area where the two FRP plates are folded back on the core material to be manufactured accurately and simply in the shape as designed. In addition, in one embodiment of the present invention, the FRP plate comprises a semi-cylindrical cylindrical surface portion that is draped over and joined to a core material, a pair of inclined surface portions that are connected to both circumferential ends of the cylindrical surface portion and joined to a pair of FRP plate joining surfaces and extend toward each other, and a dome body forming surface portion that is connected to the ends of the pair of inclined surface portions and forms the dome body. Therefore, stress concentration in the FRP plate at the boundary between the bead portion and the dome body can be suppressed, which is advantageous in improving the durability of the sonar dome. In addition, in one embodiment of the present invention, if a pair of FRP plate joining surfaces are formed as curved surfaces that are displaced in a direction toward each other, even if the stress acting on the dome body becomes large when the ship is sailing at high speed, the stress acting on the FRP plate at the boundary between the bead portion and the dome body can be distributed over a wide area by the inclined surface portion, which is more advantageous in suppressing the occurrence of stress concentration in the FRP plate at the boundary between the bead portion and the dome body, and is advantageous in improving the durability of the FRP sonar dome. In one embodiment of the present invention, a pair of FRP plate joining surfaces may cross at the ends remote from the core material, or may face each other with a predetermined gap therebetween. [Brief description of the drawings]

[0007] [Figure 1] FIG. 2 is a side view of the sonar dome placed on the bottom of the vessel. [Diagram 2] (A) is a plan view of the sonar dome, (B) is a side view, and (C) is a perspective view. [Diagram 3] 1 is a cross-sectional view of a sonar dome according to a first embodiment attached to a ship bottom. FIG. [Figure 4] FIG. 2 is an enlarged view of a mounting base portion of the sonar dome of the first embodiment. [Diagram 5] FIG. 11 is an enlarged view of a mounting base portion of a sonar dome according to a second embodiment. [Figure 6] FIG. 11 is a cross-sectional view of a sonar dome according to a third embodiment attached to the bottom of a ship. [Figure 7]FIG. 13 is an enlarged view of a mounting base portion of the sonar dome of the third embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. First, the first embodiment will be described with reference to FIGS. As shown in FIG. 1, a transducer 12 is installed on the bottom of a ship 10, and a sonar dome 14 is provided to cover the transducer 12. As shown in FIG. 2, the sonar dome 14 has an elongated shape extending along the extension direction of the ship, and is open at the top. As shown in Figures 2(A) and (C), when viewed in a plan view, the outline of sonar dome 14 is formed by semicircular arc portions at both ends in the longitudinal direction and two opposing straight lines connecting the ends of the semicircular arc portions. Also, as shown in Figure 2 (B), when viewed from the side, the height of sonar dome 14 is greatest at the center in the longitudinal direction and gradually decreases toward both ends, and the height of sonar dome 14 viewed from the longitudinal direction is greatest at the center in the width direction (not shown) and gradually decreases toward the outside in the width direction.

[0009] As shown in FIG. 3, the sonar dome 14 includes a bead portion 16 and a dome body 18A. The dome body 18A includes an antifouling rubber layer 20. The bead portion 16 is attached around its entire periphery to the ship bottom 10 and serves to maintain the shape of the sonar dome 14, and is provided around the entire upper edge of the dome body 18A. The bead portion 16 is configured to include a core material 22 . The core material 22 can be made of various flexible materials that are well known in the art, such as one or more flexible wires covered in a circular shape with rubber, or a flexible rope made of synthetic fibers covered in a circular shape with rubber.

[0010] As shown in FIG. 4, the bead portion 16 includes, in addition to the core material 22, an outer peripheral rubber layer 24, an FRP (Fiber Reinforced Plastics) plate 26A, a sealing rubber layer 28, and a gap blocking rubber 30A. The peripheral rubber layer 24 covers the peripheral surface of the core material 22 . The FRP plate 26A is hung on the core material 22 from above the outer circumferential rubber layer 24 and folded back to extend from the bead portion 16 to the dome main body 18A. The sealing rubber layer 28 is provided to securely hold the sonar dome 14 in place on the bottom of the vessel 10, and more specifically, is provided to cover the bead portion 16, which is the portion to be attached on the bottom of the vessel 10, and the FRP plate 26A in the vicinity of the bead portion 16. As shown in FIG. 3, if the portion of the sonar dome 14 that is attached to the bottom of the vessel 10 is referred to as the mounting base 1402, the mounting base 1402 is configured to include the bead portion 16 and the portion of the dome body 18A close to the bead portion 16, and the sealing rubber layer 28 is provided on the mounting base 1402.

[0011] As shown in FIG. 4, the gap blocking rubber 30A is pre-vulcanized and molded in a cross-sectional shape in which its thickness gradually decreases with increasing distance from the core material 22, and blocks the gap S formed between the core material 22 and two FRP plates 26A folded back from the core material 22. In this embodiment, since the core material 22 is covered with the peripheral rubber layer 24, the gap blocking rubber 30A is pre-vulcanized molded into a cross-sectional shape that blocks the gap S formed between the peripheral rubber layer 24 and the two FRP plates 26A folded back from the peripheral rubber layer 24, thereby blocking the gap S. Since the gap blocking rubber 30A is located at a portion of the FRP plate 26A that is subjected to large stress when the ship is traveling at high speed, the gap blocking rubber 30A is preferably formed of hard rubber having a hardness of JIS A 50 degrees or more and JIS A 80 degrees or less so that it will not deform even when subjected to large stress. In consideration of durability, functionality, and moldability, it is even more preferable that the hardness of the gap blocking rubber 30A be JIS A 60 degrees or more and JIS A 70 degrees or less. If the hardness is less than JIS A 50 degrees, the gap blocking rubber 30A will deform every time it receives stress, and the FRP plate 26A will also deform accordingly, which is undesirable in terms of durability. Furthermore, if the hardness exceeds JIS A 80 degrees, it becomes difficult to form the shape of the gap blocking rubber 30A with high precision, and it is not possible to make it conform to the shape of the semicircular arc portions at both ends of the dome.

[0012] The gap blocking rubber 30A has a cylindrical core material joining surface 3002 which is joined to the outer peripheral surface of the core material 22 via the outer rubber layer 24, and a pair of FRP plate joining surfaces 3004 which extend from both circumferential ends of the core material joining surface 3002 at an angle approaching each other and join the locations of two FRP plates 26A which are folded back by the core material 22. A pair of FRP plate joining surfaces 3004 are formed of curved surfaces 3010 that are displaced in directions approaching each other. The pair of FRP plate joining surfaces 3004 intersect at the ends remote from the core material 22 . The bead portion 16 is the portion of the sonar dome 14 located around the core material 22, and in this embodiment is composed of the core material 22, the peripheral rubber layer 24, the gap blocking rubber 30A, the portion of the FRP plate 26A located around the core material 22, the peripheral rubber layer 24, and the gap blocking rubber 30A, and the sealing rubber layer 28, and the dome main body 18A refers to the portion of the sonar dome 14 excluding the bead portion 16.

[0013] The FRP plate 26A, which is folded at the bead portion 16 into two pieces, passes through the FRP plate joining surface 3004 of the gap blocking rubber 30A, and then is overlapped and joined, and the dome body 18A is formed by the two overlapping FRP plates 26A. The dome body 18A has an inner surface 1802 facing the transducer 12 and an outer surface 1804 facing away from the transducer 12 . The antifouling rubber layer 20 prevents adhesion of marine organisms and the like, and is attached to the outer surface 1804 of the dome body 18A.

[0014] Next, a method for manufacturing the sonar dome 14 will be described. First, a strip of unvulcanized rubber for forming the peripheral rubber layer 24 is wound around the entire length of the core material 22 . Next, a gap blocking rubber 30A that has been previously vulcanized and has a core material joining surface 3002 and a pair of FRP plate joining surfaces 3004 is placed so that the core material joining surface 3002 is superimposed on the outer peripheral surface of the unvulcanized rubber for forming the outer peripheral rubber layer 24. Next, the prepreg for forming FRP plate 26A is overlapped and hung on half of the outer peripheral surface of the unvulcanized rubber for forming peripheral rubber layer 24, and then the prepreg for forming FRP plate 26A which has been folded back into two sheets is overlapped on the remaining half of the outer peripheral surface of the unvulcanized rubber for forming peripheral rubber layer 24 and a pair of FRP plate joining surfaces 3004, and after passing through the pair of FRP plate joining surfaces 3004, the two prepregs for forming FRP plate 26A which have been folded back are overlapped against each other.

[0015] Next, the unvulcanized rubber for forming the seal rubber layer 28 is laid over the portion of the prepreg for forming the FRP plate 26A that corresponds to the mounting base 1402. Furthermore, unvulcanized rubber for forming the stain-resistant rubber layer 20 is laid over the remaining prepreg for forming the FRP plate 26A excluding the mounting base 1402. By placing the materials in this overlapping state in a mold and vulcanizing them, the rubber contained in core material 22, the unvulcanized rubber used to form peripheral rubber layer 24, the unvulcanized rubber used to form sealing rubber layer 28, and the unvulcanized rubber used to form anti-fouling rubber layer 20 are vulcanized to form core material 22, peripheral rubber layer 24, sealing rubber layer 28, and anti-fouling rubber layer 20, and the prepreg used to form FRP plate 26A hardens due to the heat during vulcanization molding to form FRP plate 26A, and sonar dome 14 is manufactured.

[0016] During vulcanization molding, the portion of the prepreg for forming the FRP plate 26A that is hung on the core material 22 is superimposed on the outer peripheral surface of the unvulcanized rubber for forming the outer peripheral rubber layer 24 and hardens, so that this prepreg portion is joined to the outer peripheral surface of the core material 22 via the outer peripheral rubber layer 24, and is formed as a cylindrical surface portion 2608 having a semi-cylindrical surface shape that corresponds to the outer peripheral surface of the outer peripheral rubber layer 24. During vulcanization molding, the two prepregs used to form the FRP plate 26A folded back from the core material 22 are overlapped on a pair of FRP plate joining surfaces 3004 and hardened, so that the two FRP plate 26A folded back from the core material 22 are joined to the pair of FRP plate joining surfaces 3004 and are formed as a pair of inclined surface portions 2610 extending toward each other. In this embodiment, the inclined surface portion 2610 is formed as a curved surface corresponding to the curved surface 3010 of the FRP plate joining surface 3004 . The ends of the pair of inclined surface portions 2610 and both circumferential ends of the cylindrical surface portion 2608 are continuously connected to each other.

[0017] In addition, the portion of the prepreg for forming the two FRP plates 26A sandwiched between the sealing rubber layer 28 at the mounting base 1402 where the gap blocking rubber 30A passes is formed as a flat dome body forming surface portion 2612 that forms the dome body 18A, and the remaining portions of the dome body forming surface portion 2612 excluding the mounting base 1402 are formed of flat surfaces and curved surfaces as shown in Figure 2. Similarly, the seal rubber layer 28 is formed of a cylindrical surface portion 2808, a curved surface portion 2810, and a flat surface portion 2812 that correspond to the cylindrical surface portion 2608, the inclined surface portion 2610, and the dome main body forming surface portion 2612 of the FRP plate 26A. In this embodiment, the attachment base 1402 including the bead portion 16 is provided symmetrically with respect to the center line passing through the center of the core material.

[0018] As shown in FIG. 3, the sonar dome 14 is attached to the bottom of the vessel 10 via a mounting member 34 on the vessel side, which is made up of a bead seat 36 and a bead clamp 38 as mounting fixtures. The mounting member 34 is a plate-like member attached to the bottom of the ship 10, and extends in the shape of a long, thin frame around the transducer 12 and following the shape of the sonar dome 14 in a plan view. The mounting member 34 may be an elongated frame-like integral member, or may be configured by joining together a plurality of divided bodies separated in the extending direction. A plurality of first bolt insertion holes H1 are formed through the outer periphery of the mounting member at intervals in the direction in which the mounting member extends.

[0019] The bead seat 36 extends in an elongated frame shape corresponding to the shape of the bead portion 1620 in a plan view. The bead seat 36 is made of metal or synthetic resin. The bead seat 36 may be formed as a single piece in the shape of an elongated frame, or may be configured by joining a plurality of segments separated in the extending direction. The bead seat 36 has an upper surface 3602 facing upward, a bead seat side mating surface 3604, and a bead seat side clamping surface 3606.

[0020] The upper surface 3602 is formed with a plurality of first screw holes N1 spaced apart in the extending direction of the bead seat . The bead seat side mating surface 3604 is provided on the upper part of the bead seat 36 facing the transducer 12, and the bead seat side clamping surface 3606 is provided on the lower part of the bead seat 36 facing the transducer 12. The bead seat side mating surface 3604 is formed with a plurality of second screw holes N2 spaced apart in the extending direction of the bead seat . The bead seat side clamping surface 3606 is a location for clamping the mounting base 1402 of the sonar dome 14, and the bead seat side clamping surface 3606 has a cylindrical surface corresponding to approximately half of the cylindrical surface portion 2808 of the sealing rubber layer 28, a curved surface corresponding to the curved surface portion 2810 of the sealing rubber layer 28, and a flat surface corresponding to the flat portion 2812 of the sealing rubber layer 28.

[0021] The bead clamp 38 extends around the entire circumference of the bead seat side mating surface 3604 and the bead seat side clamping surface 3606 of the bead seat 36 . The bead clamp 38 is made of metal or synthetic resin. The bead clamp 38 may be integrally molded into an elongated frame shape corresponding to the planar shape of the bead seat 36, or may be constructed by joining together multiple segments separated in the extension direction. The bead clamp 38 has an inner surface 3802 facing the transducer 12, a bead clamp side mating surface 3804, and a bead clamp side clamping surface 3806.

[0022] The bead clamp side mating surface 3804 is provided on the upper part of the bead clamp 38 facing away from the transducer 12, and the bead clamp side clamping surface 3806 is provided on the lower part of the bead clamp 38 facing away from the transducer 12. A plurality of second bolt insertion holes H2 are formed in the inner surface 3802 at intervals in the extending direction of the bead seat 36, and these second bolt insertion holes H2 penetrate to the bead clamp side mating surface 3804. The bead clamp side clamping surface 3806 is a portion for clamping the mounting base 1402 of the sonar dome 14, and has a cylindrical surface corresponding to approximately half of the cylindrical surface portion 2808 of the sealing rubber layer 28, a curved surface corresponding to the curved surface 3010 of the sealing rubber layer 28, and a flat surface corresponding to the flat portion 2812 of the sealing rubber layer 28.

[0023] When attaching the sonar dome 14 to the bottom of the vessel 10, the bead sheet side clamping surface 3606 of the bead sheet 36 and the bead clamp side clamping surface 3806 of the bead clamp 38 are aligned with the mounting base 1402 of the sonar dome 14, the bead sheet side mating surface 3604 of the bead sheet 36 and the bead clamp side mating surface 3804 of the bead clamp 38 are aligned, the bead clamp 38 and the bead sheet 36 are fastened together by the second bolt B2 which is inserted into the second bolt insertion hole H2 and screwed into the second screw hole N2, and the mounting base 1402 of the sonar dome 14 is clamped by the bead sheet side clamping surface 3606 and the bead clamp side clamping surface 3806. Then, the upper surface 3602 of the bead seat 36 is aligned with the lower surface of the mounting member 34 attached to the bottom of the ship 10, and the bead seat 36 is attached to the mounting member 34 by the first bolt B1 inserted into the first bolt insertion hole H1 and screwed into the first screw hole N1, thereby positioning the sonar dome 14 on the bottom of the ship 10.

[0024] According to the sonar dome 14 of this embodiment, the following actions and effects are achieved. In the sonar dome 14 of this embodiment, the dome body 18A is made of an FRP plate 26A and is more rigid than a conventional rubber dome body 18A, which is advantageous in preventing deformation of the dome body 18A even when subjected to large stresses during high-speed navigation and is advantageous in suppressing an increase in resistance of the bottom of the ship 10 during high-speed navigation. Furthermore, the FRP plate 26A is hung around approximately half of the core material 22 at the bead portion 16 and folded back, and is not wound around the entire circumference of the core material 22. That is, when the FRP plate 26A is wound around the entire circumference of the core material 22, the FRP plate 26A becomes circular around the core material 22, and when it moves away from the core material 22, the FRP plate 26A becomes plate-like with a thickness smaller than the outer diameter of the circular FRP plate 26A wound around the core material 22, and the shape of the FRP plate 26A changes suddenly at the boundary between the bead portion 16 and the dome main body 18A. Therefore, when the FRP plate 26A is wound around the entire circumference of the core material 22, if the stress acting on the dome main body 18A becomes large when the ship is traveling at high speed, stress concentration occurs at the portion of the FRP plate 26A at the boundary between the bead portion 16 and the dome main body 18A, which is disadvantageous in improving the durability of the sonar dome 14.

[0025] In contrast to this, in the present embodiment, the FRP plate 26A is wrapped around the core material 22 in approximately half of its outer periphery, and in approximately the remaining half of the outer periphery of the core material 22, it is formed as an inclined surface portion 2610 extending along the FRP plate joining surface 3004 of the gap blocking rubber 30A which has been pre-molded with a cross-sectional shape in which the thickness gradually decreases. Therefore, the cross-sectional shape of the two FRP plates 26A folded back by the core material 22 and facing each other changes gradually at the boundary between the bead portion 16 and the dome main body 18A, without any sudden change. Therefore, even if the stress acting on the dome main body 18A becomes large when the ship is traveling at high speed, stress concentration in the FRP plate 26A at the boundary between the bead portion 16 and the dome main body 18A can be suppressed, which is advantageous in improving the durability of the sonar dome 14. Furthermore, when manufacturing the sonar dome 14, the FRP plate joining surface 3004 of the gap blocking rubber 30A can be used as a mold surface for the inclined surface portion 2610 of the FRP plate 26A, which is advantageous in accurately and simply manufacturing the portion of the two FRP plates 26A folded over by the core material 22, i.e., the pair of inclined surface portions 2610 of the FRP plate 26A, in the designed shape.

[0026] In addition, in the present invention, the pair of FRP plate joining surfaces 3004 of the gap blocking rubber 30A may be formed as flat surfaces, but if the pair of FRP plate joining surfaces 3004 are formed as curved surfaces 3010 that displace in directions toward each other, as in the present embodiment, the portions of the two FRP plates 26A folded back by the core material 22 are also formed as inclined surface portions 2610 consisting of curved surfaces corresponding to the curved surfaces 3010 of the FRP plate joining surfaces 3004. Therefore, even if the stress acting on the dome main body 18A becomes large when the ship is traveling at high speed, the stress acting on the FRP plate 26A at the boundary between the bead portion 16 and the dome main body 18A can be dispersed over a wide area by the inclined surface portion 2610, which is more advantageous in suppressing the occurrence of stress concentration in the FRP plate 26A at the boundary between the bead portion 16 and the dome main body 18A and is advantageous in improving the durability of the FRP sonar dome 14.

[0027] Next, a second embodiment will be described with reference to FIG. In the following description of the embodiment, the same reference numerals are used for parts and components similar to those of the first embodiment, and their description will be omitted or simplified, and the description will focus on the parts that are different from the first embodiment. In the second embodiment, the shape of the gap blocking rubber 30B and the structure of the dome body 18B are different from those in the first embodiment. In the first embodiment of the gap blocking rubber 30A, a pair of FRP plate joining surfaces 3004 formed by the curved surfaces 3010 intersect at the end away from the core material 22, whereas in the second embodiment of the gap blocking rubber 30B, a pair of FRP plate joining surfaces 3004 formed by the curved surfaces 3010 face each other at a predetermined distance apart at the end away from the core material 22. The pair of FRP plate joining surfaces 3004 are connected at a connection surface 3020 at the end portions remote from the core material 22 .

[0028] In the mounting base 1402 of the sonar dome 14, as in the first embodiment, the FRP plate 26A has a cylindrical surface portion 2608, a curved inclined surface portion 2610, and a flat dome body forming surface portion 2612, and the sealing rubber layer 28 has a cylindrical surface portion 2808, a curved surface portion 2810, and a flat portion 2812. In addition, the dome body 18, excluding the areas where the core material 22 and the gap blocking rubber 30B are located, is composed of two dome body forming surface portions 2612 and a dome body rubber layer 40A joined and sandwiched between these dome body forming surface portions 2612. An end of this dome body rubber layer 40A is joined to a connecting surface 3020 of the gap blocking rubber 30A.

[0029] The manufacturing method of the sonar dome 14 in the second embodiment is almost the same as that in the first embodiment, but differs from the first embodiment in that the unvulcanized rubber for forming the dome main body rubber layer 40A is positioned by aligning its end with the connection surface 3020A of the gap blocking rubber 30A, and that the prepreg for forming the FRP plate 26A is superimposed on approximately half of the outer peripheral surface of the unvulcanized rubber for forming the outer peripheral rubber layer 24, a pair of FRP plate joining surfaces 3004 of the gap blocking rubber 30A, and both sides of the unvulcanized rubber for forming the dome main body rubber layer 40A. The second embodiment as described above also provides the same effects as the first embodiment. Furthermore, in the second embodiment, the dome body rubber layer 40A is interposed between the dome body forming surface portion 2612 which is folded over at the core material 22 into two pieces, which is more advantageous in preventing deformation of the dome body 18 even if it is subjected to large stress during high-speed navigation, and is more advantageous in suppressing an increase in resistance of the ship bottom 10 during high-speed navigation.

[0030] Next, a third embodiment will be described with reference to FIGS. In the third embodiment, as shown in FIG. 6, the shape of the gap blocking rubber 30A is the same as in the first embodiment, and also like the second embodiment, the dome body 18 is composed of a dome body rubber layer 40B and two FRP plates 26C that sandwich the dome body rubber layer 40B. However, it differs from the first and second embodiments in that two FRP plates, a first FRP plate 26B and a second FRP plate 26C, are used at the core material 22 and at the portion of the dome body 18 close to the core material 22.

[0031] As shown in FIG. 7, in the third embodiment, the first FRP plate 26B is joined from above the peripheral rubber layer 24 to approximately half of the outer peripheral surface of the peripheral rubber layer 24, and is formed with a cylindrical surface portion 2608B having a semi-cylindrical surface shape corresponding to approximately half of the outer peripheral surface of the peripheral rubber layer 24. In addition, the portion of the first FRP plate 26B that is folded back from the outer peripheral rubber layer 24 to form two pieces is joined to a pair of FRP plate joining surfaces 3004 of the gap blocking rubber 30A, and is formed as a curved, inclined surface portion 2610B that corresponds to the curved surfaces 3010 of the pair of FRP plate joining surfaces 3004. In addition, the two first FRP plates 26B that have passed through the gap blocking rubber 30A are joined together to form a dome main body forming surface portion 2612B consisting of flat surfaces, and as shown in Figure 6, the two dome main body forming surface portions 2612B extend to a point away from the mounting base 1402.

[0032] In addition, the second FRP plate 26C is joined to approximately half of the outer peripheral surface of the cylindrical surface portion 2608B of the first FRP plate 26B, and is formed with a cylindrical surface portion 2608C having a semi-cylindrical surface shape that corresponds to approximately half of the outer peripheral surface of the cylindrical surface portion 2608B. In addition, the portion of the second FRP plate 26C that is folded back from the core material 22 to form two pieces is joined to the inclined surface portion 2610B of the first FRP plate 26B, and is formed with a curved inclined surface portion 2610C that corresponds to the inclined surface portion 2610B of the first FRP plate 26B. In addition, the second FRP plate 26C, which has split into two at the point where it passes through the gap blocking rubber 30A, becomes a flat dome body forming surface portion 2612C joined to both sides of the first FRP plate 26B, which are joined to each other at the mounting base 1402, and after passing through the mounting base 1402 and the first FRP plate 26B, it is joined to both sides of the dome body rubber layer 40B, as shown in Figure 6. In the mounting base 1402 of the sonar dome 14, the sealing rubber layer 28 is provided on the second FRP plate 26C, and the sealing rubber layer 28 has a cylindrical surface portion 2808, a curved surface portion 2810, and a flat surface portion 2812 corresponding to the cylindrical surface portion 2608C, the inclined surface portion 2610C, and the dome main body forming surface portion 2612C of the second FRP plate 26C.

[0033] The manufacturing method of the sonar dome 14 in the third embodiment is almost the same as that in the first embodiment, but differs from the first embodiment in that unvulcanized rubber for forming the dome main body rubber layer 40B is placed in line with the end of the prepreg for forming the first FRP plate 26B, and that a prepreg for forming the second FRP plate 26C is placed on top of the prepreg for forming the first FRP plate 26B and the unvulcanized rubber for forming the dome main body rubber layer 40B before placing the unvulcanized rubber for forming the sealing rubber layer 28. The third embodiment as described above also provides the same effects as the first embodiment. Furthermore, in the third embodiment, the dome body rubber layer 40A is interposed between the second FRP plate 26C which is folded over at the core material 22 to form two plates. As a result, similar to the second embodiment, this is more advantageous in preventing deformation of the dome body 18 even when subjected to large stress during high-speed navigation, and is more advantageous in suppressing an increase in resistance of the ship's bottom 10 during high-speed navigation. In addition, since two FRP plates, the first FRP plate 26B and the second FRP plate 26C, are interposed in the mounting base 1402 of the sonar dome 14, the rigidity of the mounting base 1402 of the sonar dome 14 is increased, which is more advantageous in terms of increasing the durability of the sonar dome 14. Furthermore, when the stress acting on the dome main body 18 becomes large when the ship is traveling at high speed, the effect of suppressing the occurrence of stress concentration by dispersing the stress acting on the first and second FRP plates 26B, 26C at the boundary between the bead portion 16 and the dome main body 18 over a wide area by the inclined surface portions 2610B, 2610C is exerted in the same manner as the inclined surface portion 2610 of the FRP plate 26A in the first embodiment and the inclined surface portion 2610 of the first FRP plate 26B in the second embodiment. [Explanation of symbols]

[0034] 10. Bottom of the Ship 12 Transmitter / Receiver 14 Sonar Dome 1402 Mounting base 16 Bead section 18A, 18B Dome body 1802 Inside 1804 Exterior 20 Antifouling rubber layer 22 Core material 24 Outer rubber layer 26A FRP board 26B 1st FRP board 26C 2nd FRP board 2608,2608B, 2608C Cylindrical surface part 2610, 2610B, 2610C Slope section 2612, 2612B, 2612C Dome body forming surface part 28 Sealing rubber layer 2808 Cylindrical surface part 2810 Curved surface section 2812 Plane section 30A, 30B Gap-blocking rubber 3002 Core material joining surface 3004 FRP plate joining surface 3010 Curved Surface 3020 Connection surface 34 Mounting material 36 Bead seat 3602 Top surface 3604 Bead seat side mating surface 3606 Bead seat side clamping surface 38 Bead clamp 3802 Inside 3804 Bead clamp side mating surface 3806 Bead clamp side clamping surface 40A, 40B Dome body rubber layer S Gap

Claims

1. A sonar dome comprising a bead portion having a core material and attached to a hull side, and a dome body extending from the bead portion, The dome body is made up of FRP plates overlapped and joined to each other, which has a higher rigidity than a rubber dome body and suppresses deformation due to water resistance during high-speed navigation, The FRP plate is folded back around the core material at the bead portion, A gap-closing rubber is disposed in a gap formed between the core material and a portion where the FRP plate is folded back from the core material, the gap-closing rubber being made of hard rubber and vulcanized to have a cross-sectional shape whose thickness gradually decreases with increasing distance from the core material, and which closes the gap. A sonar dome that features

2. The gap blocking rubber has a core material joining surface that is joined to the outer peripheral surface of the core material, and a pair of FRP plate joining surfaces that extend from both ends of the core material joining surface in the circumferential direction while inclining in a direction approaching each other, The FRP plate includes a cylindrical surface portion having a semi-cylindrical shape that is hung on and joined to the core material, a pair of inclined surface portions that are connected to both circumferential ends of the cylindrical surface portion and joined to the pair of FRP plate joining surfaces and extend while approaching each other, and a dome body forming surface portion that is connected to the ends of the pair of inclined surface portions and forms the dome body.

2. The sonar dome of claim 1.

3. The pair of FRP plate joining surfaces are formed by curved surfaces that are displaced in a direction approaching each other, The pair of inclined surface portions are formed with curved surfaces corresponding to the curved surface.

3. The sonar dome according to claim 2.

4. The pair of FRP plate joining surfaces intersect at the end away from the core material.

4. The sonar dome according to claim 2 or 3.

5. The pair of FRP plate joining surfaces face each other at a predetermined distance from the core material.

4. The sonar dome according to claim 2 or 3.

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