JP2010264944A - Marine propeller blade and related forming method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a marine propeller blade, using composite material made of low-cost reinforced fiber with no likelihood of resource exhaustion, which withstands cavitation erosion. <P>SOLUTION: In the marine propeller blade, at least a surface of the blade includes aramid fiber cloth material or surface layer material composed of aramid fiber uinidirectional materials laminated in the same axial direction or different axial directions, with the surface layer material being covered on a structural material serving as core material. The structural material may include carbon fiber reinforced resin or glass fiber reinforced resin. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a wing of a marine propeller that suppresses cavitation erosion by using a composite material made of fiber reinforced resin, in particular, a composite material reinforced with aramid fibers, and a method for forming the same.

  In ship propellers, the biggest problem is erosion based on cavitation generated in the wing (hereinafter referred to as cavitation erosion). As cavitation erosion progresses, not only is the propulsion efficiency lowered, but the wing may be damaged. For this reason, various studies have been conducted to suppress cavitation erosion. For example, the wing shape was devised to change the pitch according to the wing diameter, or the material was less likely to cause cavitation erosion. However, it is said that the suppression of cavitation erosion from the shape of the wing has already reached its limit, and improvements from the field of materials are expected.

  Recently, various new materials have been developed, and among them, composite materials such as non-ferrous materials such as fiber reinforced resin are attracting attention. Composite materials have advantages such as high specific strength and high rigidity, light weight and low cost, and are widely used in aircraft, spacecraft, tanks, and the like. In addition, metal materials represented by copper are concerned about resource depletion, but composite materials do not have that concern. Therefore, it has been studied whether this composite material can be used for marine propellers, and some of them have been put into practical use for submarine propellers and the like that are relatively difficult to generate cavitation. However, erosion resistance is not as good as aluminum bronze, so commercial propellers are being put to practical use.

  The following prior art is an example of applying a composite material to a propeller. Patent Document 1 discloses a technique in which the intermediate part between the leading edge and the trailing edge of the blade is a laminated FRP, but the laminated FRP here is not described in any way, and its effect is also reduced in weight. It is only about prevention of biofouling and no erosion. Patent Document 2 discloses a technique in which an aramid fiber string is wound around the wing surface of an airplane propeller. The surface side of the aramid fiber is covered with a carbon fiber and a jacket in order, and the aramid fiber itself is on the surface. It is not exposed. In addition, erosion is not so much a problem with airplane propellers, so naturally erosion is not mentioned.

  Patent Document 3 discloses a technology in which a lining layer is provided on the surface of a porous sintered metal in a plain bearing, and the aramid fiber that is made into a fine fiber is included in the lining layer, and the effect thereof is wear due to cavitation erosion. Will be improved. However, the aramid fiber here is an additive that is added together with the particulate wear-resistant filler to reinforce the resin matrix mainly composed of tetrafluoroethylene, and the addition amount is also 2 to 10% by volume. Only a few short fibers having a length of 0.2 to 1.0 mm are added in a dispersed state. The present invention aims to improve erosion resistance by making aramid fiber cloth material into a sheet and laminating and sticking it on the surface of a wing of a ship propeller. Different.

JP 58-101897 A Japanese Patent Laid-Open No. 02-085096 Japanese translation of PCT publication No. 2002-506176

  The present invention is a review of the composite material described above as the material of the wing, and in particular, by adopting an aramid fiber as the material, it enjoys the advantages of the light weight, elasticity, and low cost of the composite material while being resistant to erosion. It has been found that it can sufficiently withstand practical use by improving the above.

  Under the above problems, the present invention provides a marine propeller blade according to claim 1, wherein at least the surface of the wing is formed of a surface layer material in which aramid fiber cloth material is laminated. 4. A means for providing a wing, wherein the unidirectional material of aramid fibers is laminated in the same axial direction or different axial directions instead of the lamination of the aramid fiber cloth material according to claim 2. The means which coat | covered the surface layer material in the structural material used as core material described in 1 and the means which made the structural material the carbon fiber reinforced resin or the glass fiber reinforced resin described in Claim 4 are provided.

  Further, according to the present invention, as a method of forming the wing, the surface layer material described in claim 5 is laminated or the surface layer material is laminated on the front and back of the structural material and sealed in a vacuum bag, and is thermoset into the vacuum bag. A means for sucking the resin material and impregnating the surface layer material or the structural material, and thermosetting the resin material to integrate the surface layer material or the structural material, wherein the thermosetting resin material is impregnated in advance. A means of laminating the surface layer material of the prepreg or laminating the surface layer material of the prepreg on the front and back of the structural material and enclosing it in a vacuum bag, thermosetting the resin material, and integrating the surface material or the surface material and the structural material, The thermosetting resin material according to claim 7 is an epoxy resin as the thermosetting resin material according to claim 6.

  In the invention of claim 1, the surface of the wing is constituted by a surface layer material made of a cloth material of aramid fibers, and according to this, it has been found that the erosion resistance is greatly improved as compared with the conventional composite material. Naturally, the wings are lighter and more flexible than metal materials, leading to weight savings and reducing the capacity of the drive system, reducing stern vibration and improving comfort. There are various excellent effects. Furthermore, since the specific strength is high, the blade pressure can be reduced and the occurrence of cavitation can be suppressed. In addition, the cloth material of aramid fiber can be replaced by the unidirectional material of claim 2, and according to the means of claims 3 and 4, the strength of the entire blade can be increased.

  The wing forming method described above includes the VaRTM method (vacuum suction method) according to claim 5 and the prepreg / autoclave method according to claim 6, but according to the former, it can be easily formed on the user side, According to this, an epoxy resin having a strong adhesive force can be used as the thermosetting resin material, and a surface layer material / structural material having a high unity can be formed.

It is explanatory drawing in the case of producing the cloth material of an aramid fiber. It is a front view of the principal part of the test apparatus of an erosion test. It is a graph which shows the relationship between the time passage in each test piece, and the amount of wear. It is a graph which shows the wear rate of each test piece. It is a surface photograph which shows the wear condition of each test piece. It is a surface photograph which shows the wear condition of a carbon fiber and an aramid fiber.

  First, it was decided to study the surface layer material (and the structural material, hereinafter simply referred to as the surface layer material). In the present invention, since the surface of the blade is composed of the surface layer material, the boss portion fitted to the propeller shaft is applied to the surface layer material only on the blade portion as a conventional metal. Therefore, in actual application, a groove or the like is formed on the surface of the boss and a wing is fitted to the groove, or an attachment piece is projected from the surface of the boss and the wing is fixed thereto.

○ Selection of surface layer material Since the surface layer material is also a strength material, a material having high strength is suitable (it is preferable that the material is light at the same time). From this viewpoint, in this example, the fibers constituting the surface layer material are carbon fibers (CFRP). ), Glass fiber (GFRP) and aramid fiber (AFRP) were selected. Aramid fiber is a polyamide-based organic fiber similar to nylon fiber. Nylon is an aliphatic polyamide, whereas aramid is an aromatic polyamide. It is generally known that the fiber has high strength and high wear resistance.

○ Fiber weaving and orientation of the surface layer material Since the surface layer material must finally be in the form of a sheet, the fiber weaving method and orientation were variously selected. In the weaving method and orientation, there are a cloth material and a unidirectional material, the former is woven with warp and weft fibers (Fabric), and the latter is impregnated with resin by aligning the fibers in one direction, Stitched with yarn so that the fibers do not fall apart. Usually, the unidirectional material is laminated (Multi Axis) with the direction of fibers directed in different directions (for example, ± 45 °). In this example, a cloth material was selected for carbon fiber, glass fiber, and aramid fiber.

○ Selection of resin material (adhesive) Each sheet is bonded and laminated. At this time, a thermosetting resin material is used as the adhesive. There are various types of thermosetting resins such as phenol resins and amino resins. Here, two types of epoxy resins having strong adhesive strength were selected. In addition, an epoxy resin is a general term for compounds having an epoxy group, and is generally known to form a three-dimensional cured polymer when used in combination with a curing agent (a compound having active hydrogen such as phenol or amine). Yes. Epoxy resins are widely used in electrical insulating materials, laminating agents, paints and the like in addition to adhesives having strong adhesive strength. Table 1 shows combinations of the epoxy resin main agent and the curing agent by resin numbers (VaRTM in the left column is a method of forming a laminate described later).

○ Molding (Lamination) Method The reinforcing fiber sheet is laminated and integrated so as to have a predetermined thickness. As this integration (molding) method, the VaRTM method and the prepreg / autoclave method (hereinafter referred to as “the prepreg autoclave method”) are used. Prepreg method). In the former, the laminated sheets are sealed in a vacuum bag and evacuated, and the resin material is sucked and impregnated between the fibers and between the sheets. The latter is bonded using a sheet pre-impregnated with the resin material. Means a material using an impregnated resin material. In this example, molding was performed by a low-cost and simple VaRTM method (vacuum suction method). FIG. 1 is an explanatory diagram showing the method, in which a predetermined number of surface layer materials made of reinforcing fiber sheets are stacked and sealed in a vacuum bag, and air is supplied from one “suction port” of the vacuum bag by a vacuum pump. While sucking, the resin material is sucked from the “injection port” of the thermosetting resin material filling chamber connected to the other by this suction force, impregnated in and between the sheets, and this is pressurized and heated to resin The material is cured to integrate the surface layer material. In addition, when using an epoxy resin as a thermosetting resin material, it attracts | sucks, mixing a main ingredient and a hardening | curing agent.

  Since this method is based on an osmotic pressure method using negative pressure, it has an advantage that the resin material penetrates uniformly into the sheet. However, since the epoxy resin has a high viscosity, a high negative pressure is required and it takes time. In an actual wing, it is needless to say that the surface layer material is previously formed into the shape of the wing. On the other hand, as described above, there is also a prepreg method for integrating the sheets. In this case, a fiber reinforced sheet pre-impregnated with a strong adhesive epoxy resin as a resin material is stacked in a vacuum bag. These are sealed and pressed and heated to dissolve the epoxy resin and to integrate the sheets. According to the prepreg method, since the resin material impregnated in the sheet itself is used as an adhesive, there is an advantage that an epoxy resin having a high viscosity but excellent adhesive strength can be used.

  According to the above selection, a total of five types of test pieces having a size of 350 mm × 500 mm and one type of aluminum bronze (NAB) were prepared and subjected to an erosion resistance test. FIG. 2 is a side view of the principal part of this test apparatus. A vibrator 4 is provided on a test piece 3 placed on a table 2 provided in a water tank 1 containing water, and the vibrator 4 is mounted. It was carried out by a method of vibrating in the range where the test piece 2 was not brought into contact with water. When the vibrator 4 repeats approaching and moving away from the test piece 3, a change in water pressure occurs between them, bubbles are generated and collapsed, and a state close to actual cavitation is obtained. And the degree of erosion was measured by measuring the amount of wear of the test piece 3 at regular intervals.

The test conditions were set as follows.
Test piece thickness 1.7-2.3 mm
Number of layers of cloth material 2-6 layers Distance between transducer and test piece 0.5mm
Frequency 19.5KHz
Both amplitudes 50μm
Test time 120 minutes Measurement interval Every 15 minutes

FIG. 3 is a graph showing the relationship between the amount of wear and time in each test piece, and FIG. 4 is a graph of the wear rate. From this, the following was found.
The test piece (5) of aluminum bronze (NAB) had the least amount of wear, and almost no wear was observed after 120 minutes of the test time. Next, the test piece (4) and (5) of the four-layer material (AF4) and the two-layer material (AF2) of aramid fibers (AF-Fab-Var) had the least amount of wear. On the other hand, the carbon fiber (CF-Fab-Var) test piece (1) has a large amount of wear, and the glass fiber (GF-Fab-Var) test piece (2) has the largest amount. In addition, the amount of wear of the test pieces (3) and (4) was roughly 1/3 of the test piece (1) and 1/6 of the test piece (2). What can be said from this is that among the composite materials, the aramid fiber cloth material has the least amount of wear, and the amount of wear is 1/3 to 1/6 that of carbon fiber or glass fiber used in the past. .

  When the physical properties of carbon fiber, glass fiber and aramid fiber are compared, aramid fiber is the most flexible. This means that the wing surface exposed to cavitation is more flexible. The reason is presumed that the impact energy at the time of cavitation collapse can be absorbed.

  In order to support the above results, the progress of erosion of each test piece was observed with SEM photographs. FIG. 5 is an SEM photograph of each test piece after the lapse of 30 minutes, and it can be confirmed from this that peeling of the resin material and cutting of the fiber can be confirmed. Carbon fiber and glass fiber are crumpled and crumpled, and the unevenness is severe. However, the aramid fibers can be observed as if the fibers are crimped and have a resin material. Although small holes are made, they are not eroded deeply. On the other hand, aluminum bronze also shows a slight change on its surface.

  For reference, the progress of erosion was observed for aramid fibers and carbon fibers. FIG. 6 is an SEM photograph after 120 minutes, in which (a) is carbon fiber, a) is macroscopic, b) is microscopic, (b) is aramid fiber, and a) is macroscopic. B) is microscopic. From this, it can be observed that the shape of the aramid fiber remains in the length direction and the cut fiber is in a crimped state. This means that aramid fibers are stretchable and can absorb impact energy when cavitation collapses. In addition, it can be observed from the photograph that the aramid fiber has better adhesion to the resin than the carbon fiber.

The test results obtained with the five types of test pieces are summarized as follows.
Except for the aluminum bronze test piece (5), the amount of wear is small in the aramid fiber test pieces (3) and (4), which are composite test pieces made of other carbon fibers or glass fibers ( Compared with 1) and (2), it is approximately 1/3 to 1/6. This suggests that aramid fibers can be applied to actual wings. On the other hand, aluminum bronze, which is currently considered to have the highest erosion resistance, shows almost no wear even after 120 minutes. However, after 7 hours, it is observed with the naked eye that wear has occurred. did it. The test time with the above test equipment is a medium-sized ship propeller, which is about 2000 times shorter than the actual operation time. It is a well-known fact that the wing surface is scratched.

  When the erosion progressed and the wings were missing, the propeller was replaced. In other words, even if the propeller is made of aluminum bronze, propeller exchange is inevitable. The problem is the time of replacement, and it can be said that aramid fiber wings can be applied to actual wings, although the timing can be accelerated. On the other hand, carbon fiber and glass fiber wings that have been used in the past are not able to be applied to actual wings such as merchant ships because their replacement time is remarkably advanced. As described above, if the wing is made of a composite material, many advantages can be obtained by reducing the weight.

  By the way, as described above, the aramid fiber sheet includes not only a cloth material but also a sheet called a unidirectional material. In the present invention, it is confirmed that a unidirectional material may be used instead of the cloth material. Although it was tried in a parallel test, the amount of wear after 120 minutes was inferior by about 5% at the maximum, so it can withstand sufficient use.

  Since the wings of the propeller are also strength materials, the entire wing may be made of aramid fiber reinforced resin in order to manufacture the wings with composite materials, but the core part is made of carbon fiber reinforced resin or glass fiber with higher strength. Using a reinforced resin, only the surface layer material exposed to cavitation may be aramid fiber. Even in this case, a matrix containing a large amount of resin material is preferable. Since the metal is excellent in terms of strength, the core may be a metal. In this case, the epoxy resin is sufficiently practical because it has good adhesion compatibility with metal.

  The present invention is not limited to a wing of a marine propeller, but can be applied to any device or member having a portion that contacts water causing erosion. Specifically, a rudder, a pump, a pipe, etc. can be considered.

1 Water tank 2 units 3 Test piece 4 Vibrator

Claims (7)

  A wing of a marine propeller, wherein at least a surface of the wing is constituted by a surface layer material in which a cloth material of aramid fibers is laminated.   The wing | blade of the ship propeller of Claim 1 which replaced with lamination | stacking of the cloth material of the aramid fiber, and laminated | stacked the unidirectional material of the aramid fiber toward the same axial direction or a different axial direction.   The wing | blade of the ship propeller of Claim 1 or 2 which coat | covered the surface layer material in the structural material used as a core material.   The wing of a ship propeller according to claim 3, wherein the structural material is a carbon fiber reinforced resin or a glass fiber reinforced resin.   A method for forming a wing of a ship propeller according to any one of claims 1 to 4, wherein a surface layer material is laminated or a surface layer material is laminated on the front and back of a structural material and sealed in a vacuum bag, and the thermosetting resin material is put into the vacuum bag A method for forming a wing of a marine propeller, wherein the surface layer material or the structural material is impregnated and the resin material is thermally cured to integrate the surface layer material or the structural material.   It is a shaping | molding method of the wing | blade of the ship propeller in any one of Claims 1-4, Laminating | stacking the surface layer material of the prepreg impregnated with the thermosetting resin material previously, or laminating | stacking the surface layer material of a prepreg on the front and back of a structural material A method for forming a wing of a marine propeller, which is enclosed in a vacuum bag, and a resin material is thermally cured to integrate the surface layer material or the surface layer material and the structural material.   The method for forming a wing of a ship propeller according to claim 6, wherein the thermosetting resin material is an epoxy resin.