JPH038560Y2 - - Google Patents

Description

[Detailed explanation of the idea] [Industrial application field]

The present invention relates to a corrosion protection device for marine propellers.

[Conventional technology]

As an example of anti-corrosion measures for marine propellers, sacrificial materials (also called anode materials) that are more easily ionized than the propeller material, such as zinc alloys, aluminum alloys, and magnesium alloys, are used around the propeller to take advantage of the ionization tendency of metals. Corrosion prevention methods using a galvanic anode method are often used to corrode this sacrificial material. In this galvanic anode method, a sacrificial material is attached to the outer panel of the ship's hull, and the anticorrosive current generated by this material flows into the propeller, which is the object to be protected, and passes through the propeller shaft.
There are two methods: one is to return the sacrificial material to the ship's hull via the bearing or the hull grounding device, and the other is to attach the sacrificial material directly to the propeller shaft or propeller body in front of the propeller, which is the object to be protected from corrosion, without going through a conductor or grounding device. .

[Problem that the idea aims to solve]

By the way, the former method imposes a heavy burden on small and medium-sized ship owners in terms of maintenance costs such as wiring the conductor, connection to the grounding device, and maintenance of the device, and it also causes the risk of disconnection of the conductor and failure of the grounding device. There are problems with handling, and it cannot necessarily be said to be a reliable corrosion prevention method. On the other hand, since the latter method directly connects the sacrificial material and the object to be protected from corrosion, it is a reliable and effective method and has the advantage of being available at low cost. As a corrosion protection device using this latter method,
There are devices as shown in FIGS. 1 to 5. This device includes a two-part split piece 5 made of a metal that is more easily ionized than the metal constituting the shaft system device 2, and the two split pieces 5 are arranged so as to sandwich the propeller shaft 4, The assembly bolts 7 are tightened so that the opposing surfaces 6 are in close contact with each other, and the device is integrated with the propeller shaft 4 by screwing in the set bolt 8 and pressing its tip against the propeller shaft 4. The structure is said to be In addition, in FIG. 1, 1 is the stern and 11 is the rudder. However, the above structure has the following drawbacks. That is, since a counterbore is formed in a part of the divided piece 5 so that the head of the assembly bolt 7 is not exposed, the distance d between the hole 9 of the assembly bolt 7 and the outer wall surface is
Also, the distance d' between the bolt head counterbore and the inner diameter becomes extremely small, and these parts corrode and melt due to slight use in seawater, causing the bolt 7 to be exposed or fall off, and the split piece 5 to be damaged for a short period of time. It will fall out in between. Considering the corrosion capacity of the sacrificial material, this short-term falling off occurs at a consumption of 20 to 30%, and is a fatal flaw that prevents the sacrificial material from making full use of its anti-corrosion capacity. was. Moreover, in recent years, from the perspective of energy saving, there has been a trend to make the outer diameter d'' of the propeller boss 3 as small as possible compared to the conventional one in order to lower the resistance of the propeller 12 itself and improve efficiency. Therefore, the outer diameter D of the device becomes larger than the outer diameter d'' of the propeller boss 3, and the outer diameter dimension D cannot be made too small. Turbulence and excessive flow flow directly into the propeller blades, resulting in a reduction in propeller efficiency and the potential for erosion. In order to compensate for this drawback, there are models that are made into one piece rather than split into two parts, but in this case, the propeller must be pulled out from the shaft when attaching and removing the sacrificial material, and the ship This requires time and additional costs. On the other hand, a corrosion protection device as seen in Japanese Utility Model Publication No. 53-45437 has also been proposed. In this corrosion protection device, the bonnet underframe attached to the propeller boss is surrounded by divided sacrificial materials, and each of the sacrificial materials is detachably attached to the bonnet underframe using bolts. With this structure, even if a hole occurs in a part of the sacrificial material, only that part of the sacrificial material can be replaced. However, this device lacks versatility because it cannot be attached to an existing propeller that does not have such a mounting structure on the bonnet frame.
The drawback was that the manufacturing cost of the propeller itself was too high. Moreover, since the split pieces are fixed using bolts with heads, counterbore parts are formed on the split pieces, and the wall thickness of this counterbore becomes thinner, so there is a risk that the split pieces will fall off in a short period of time due to corrosion. . In view of these circumstances, the present invention is a resource-saving marine propeller that can be easily attached to existing propellers, is inexpensive, can fully consume the total capacity to the end of its service life, and can be made smaller. The purpose is to provide corrosion protection equipment.

[Means to solve the problem]

In order to achieve these objectives, this invention
A corrosion protection device for a marine propeller, which is formed into a cylindrical shape from a metal that is more easily ionized than the metal forming the propeller, and is attached to a propeller shaft so that the propeller shaft fits inside the cylinder. , is composed of a plurality of divided pieces, and this divided piece overlaps the fitting piece of the adjacent divided piece in the vertical direction, and
Fitting pieces formed so that their thickness gradually increases from the base toward the end surface protrude from both sides thereof, and the fitting pieces arranged on the propeller shaft side are in contact with the propeller shaft. A screw hole is drilled in the set bolt for rotating the propeller shaft together with the propeller shaft, and a screw insertion hole in the set bolt is drilled so as to face the screw hole in a fitting piece disposed above the screw hole. The main points of this paper are corrosion protection systems for marine propellers.

[Effect]

With the above configuration, the divided pieces are arranged so as to surround the propeller shaft, and the corresponding fitting pieces are fitted together. Then, when the set bolt is screwed into the screw hole and its tip is pressed against the propeller shaft, the fitting piece placed on the propeller shaft side is pressed against the corresponding fitting piece placed above it. The divided pieces are firmly integrated, and the device itself can rotate together with the propeller shaft.

【Example】

Hereinafter, the present invention will be explained in detail with reference to the drawings showing embodiments thereof. As shown in Figures 6 to 10, this device:
It has two divided pieces 14. Both divided pieces 14 are each provided with fitting pieces 15 on both sides. Further, each fitting piece 15 is formed so as to gradually become thicker from its base toward its end surface, and its fitting surface is tapered. A fitting piece 1 disposed on the propeller shaft 4 side
5 has a screw hole 16 into which a set bolt 18 is screwed.
A screw insertion hole (cut hole) 17 is bored in the fitting piece 15 arranged above the fitting piece 15 so as to face the screw hole 16 when assembled. This device is constructed as described above, and when the split piece 14 is arranged to sandwich the propeller shaft 4 in front of the propeller boss 3 and the fitting piece 15 is fitted, the fitting surface becomes tapered. Therefore, the mutual fitting surfaces can receive the centrifugal force due to the rotation of the propeller shaft 4, and the centrifugal force will not loosen or come off. Then, screw the set bolt 18 into the screw hole 16 and attach the tip to the propeller shaft 4.
When pressed, the fitting piece 15 on the propeller shaft 4 side is pushed up toward the fitting piece 15 above it, and both fitting surfaces are brought into close contact. At the same time, the set bolt 18 securely fixes the entire device to the propeller shaft 4 so that they rotate together. Further, the thickness of the set bolt 18 is constant over the entire circumference except for the insertion hole 17 portion, and there is no fear that the thin wall portion will corrode and fall off as in the conventional case. Furthermore, since the divided pieces can be integrated using only the headless set bolt 18, the outer diameter D can be made sufficiently smaller than the propeller boss, and problems such as a decrease in propeller efficiency and generation of aging are eliminated. In the above embodiment, the device is composed of two pieces, but it may be divided into three or four pieces.

[Effect of the idea]

The corrosion protection device for marine propellers according to the present invention is
With the structure described above, this fitting surface absorbs the force in the rotational direction of the propeller shaft to prevent it from falling out due to centrifugal force, and the set bolt can be tightened to ensure that the device rotates together with the propeller shaft. The fitting surfaces are crimped by the insertion, and the divided pieces are more strongly integrated. Therefore, it can be easily attached to an existing propeller without using assembly bolts as in the conventional case. Furthermore, by using a headless set bolt, the size of the device itself can be made sufficiently small, and there is no possibility of a decrease in propeller efficiency or the occurrence of erosion. Furthermore, there is no need to provide a counterbore portion for accommodating the heads of the assembly bolts, the thickness of the entire device becomes substantially uniform, and the total capacity can be sufficiently consumed up to the life limit.

[Brief explanation of the drawing]

Figure 1 is a side view of the stern shaft system of a ship fitted with a conventional anti-corrosion device, Figure 2 is a side view of the anti-corrosion device, Figure 3 is a cross-sectional view taken along the - line, and Figure 4 is the front of the propeller boss. FIG. 5 is a side view of the conventional corrosion protection device attached to the propeller shaft of the invention, FIG. 6 is a perspective view of divided pieces of the corrosion protection device of the present invention, and FIG. 7 is its front view. ,
FIG. 8 is a side view thereof, FIG. 9 is a sectional view showing the state in which the divided pieces are fitted together, and FIG. 10 is a side view showing the state in which it is attached to the propeller shaft. 3...Propeller boss, 4...Propeller shaft, 14
...Divided piece, 15... Fitting piece, 18... Set bolt.

Claims (1)

[Scope of utility model registration request] A corrosion protection device for a marine propeller, which is formed in a cylindrical shape from a metal that is more easily ionized than the metal forming the propeller, and is attached to the propeller shaft so that the propeller shaft fits inside the cylinder. It is composed of multiple divided pieces, and these divided pieces are
A fitting piece is formed so that it overlaps the fitting piece of the adjacent divided piece in the vertical direction and gradually increases in thickness from the base to the end face direction, and is provided on both sides of the fitting piece and protrudes from the propeller shaft side. A screw hole for a set bolt that contacts the propeller shaft and rotates together with the propeller shaft is bored in the fitting piece disposed above, and the screw hole faces the fitting piece disposed above the set bolt. A corrosion protection device for a marine propeller, characterized in that a screw insertion hole for the set bolt is bored as shown in FIG.