JPS5853624B2 - How to attach a ring-shaped structure to the stern of the hull - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for attaching a ring-shaped structure to be attached to a stern section in front of a propulsion device.

It is known that as a ship's hull becomes larger, the flow of water near the stern becomes turbulent and the flow of hot water becomes uneven, which increases the horsepower required for propulsion and increases vibration and noise.

In order to improve this drawback, a ring-shaped structure is installed at the stern of the ship, which collects the slow flow flowing on the side of the ship, spreads it, and supplies it to the operating plane of the propulsion device. This was proposed in Publication No. 7096/1983.

It has been confirmed that providing this ring-shaped structure at the stern has a remarkable effect, reducing the power required for propulsion by about 10%, and at the same time reducing vibration and noise.

For example, in the case of a 250,000 ton tanker, the ring-shaped structure has an inner diameter of approximately 900 mm (
Near 71. The width is about 450 cIrL and the weight is about 90
It is quite heavy and large, weighing up to a ton.

The positional relationship between the ring-shaped structure and the propeller must be accurate, and if the mounting position is incorrect, it is often impossible to obtain the desired improvement effect even if a highly accurate ring-shaped structure is obtained. It is.

On the other hand, as mentioned above, the ring-shaped structure is large and heavy, so the installation accuracy is likely to be lost, and the installation requires a large number of man-hours, requiring long-term work throughout the prefecture.

The present invention was devised in view of the above-mentioned circumstances and to eliminate the drawbacks, and it is possible to quickly align the center of the ring-shaped structure and the center of the thruster shaft, and to It is intended to provide a mounting method that allows accurate mounting to the stern of the ship.

The present invention achieves the above object by detecting a centering fixed point on the inner surface of a ring-shaped structure body equidistant from the central axis of the propeller shaft using a beam of light from a projector that rotates around the central axis of the propeller shaft. After the ring-shaped structure body is moved to irradiate the vessel, the ring-shaped structure body is attached to the stern of the ship with reference to the central axis of the propeller shaft.

Next, the present invention will be described in detail with reference to the drawings.

First step: The shape of the hull of the ship to which the ring-shaped structure is to be installed is investigated, a ring-shaped structure that matches this is designed in advance, and this is manufactured on the ground.

The members manufactured in this example are as follows.

Note that each member is shown in FIG.

(1) Ring-shaped structure main body 5 (2) Upper support member 6 (3) Upper end cover 7 (4) Upper rear end cover 8 Each of the above members, except for some construction holes, can be assembled, welded, and painted as members. Let it be completed.

Second step: Draw the center lines (MB)P and (MB)S of the propeller axis on both sides on the outer surface of the inner diameter of the ring-shaped structure main body 5 (see FIGS. 2A and 2B).

Third step: Draw the center lines (M-A)U and (M-A)L of the propeller axis at the top and bottom positions of the inner surface of the ring-shaped structure main body 5 (second step).
(See Figures A and B).

Fourth step Eight centering pieces 10 made of steel are manufactured, and a fixed point P on each centering piece 10 intersects a circle 11 centered on the propeller axis.
is determined on the drawing, and the fixed point P is marked on each centering piece 10 at a position measured from the inner surface of the ring-shaped structure body 5,
Each centering piece 10 is attached to the inner surface of the ring-shaped structure body 5, and a fixed point P for centering is attached to the inner surface of the ring-shaped structure body 5.
will be established.

(See Figure 3). In addition, after attaching the centering pieces 10 to the ring-shaped structure body 5, by marking the fixed points P determined on the drawing above on each centering piece 10, the inner surface of the ring-shaped structure body 5 is marked for centering. A fixed point P may be provided.

Fifth step: The hanging piece 12 is attached to the outer periphery of the ring-shaped structure 5, and the hanging piece 13 is attached to the rear end (see FIGS. 2A and B).

The front end line (MC) of a predetermined ring-shaped structure is marked on both sides of the outer plate of the sixth stage hull 1 (see Fig. 4).

The center line of the propeller shaft (M-
Mark D) using the spirit level 14 (see Figures 3 and 4).

Eighth Step: Mark the intersection point (M-2) on the center line of the outer plate of the hull 1 with the front end of the ring-shaped structure (see FIGS. 4 and 5).

During the 9th step, the ring-shaped structure body 5 prepared in the above step is carried in, connected to the rigging, lifted with a winch and carried to a predetermined position at the stern of the hull 1, and then moved to the next step. Position accurately in steps.

A. Align the line (M-1) marked on the outer panel of the hull 1 with the front end of the ring-shaped structure body 5 (see Fig. 4).

B. Position the point (M-2) marked on the stern section on the line (M-A)U of the ring-shaped structure main body 5.

Connect the point (M-1) on the stern section of C to the line on the ring structure body 5 (
M-A) Position on L.

D Line (M-A) U on ring structure body 5 and line (M
-A) Connect the rear end of L with a vertical line and confirm that the heavy chain is an extension of point (M-1) (see Figure 3).

Step 10: Place the temporary shaft to which the visible light projector, such as a laser beam, is attached, aligned with the center of the propeller shaft.

Figure 6 shows this state, where 20 is a temporary axis;
A support arm 21 is rotatably provided at intervals,
By operating the centering bolt 22 provided on this, the stern bearing 23
Rotatably fixed inside.

In this state, the temporary shaft 20 is located on the centerline of the stern bearing 23.

A holder 24 is provided at one end of the temporary shaft 20 so as to be movable up and down via a pin 25 and a light emission angle adjustment rod 26, and a laser beam projector 27 is further provided on this holder 24.

In the present invention, it is important to rotate the visible light projector with reference to the propeller axis, and by rotating the visible light projector while emitting light, the position of the ring-shaped structure with respect to the propeller axis can be accurately determined. This can be confirmed.

Therefore, in the above embodiment, a temporary shaft was used, but instead of using such a jig, for example, as shown in FIG. You can also perform centering work.

FIG. 5 shows a state in which the position where the ring-shaped structure 5 is to be attached to the stern part is confirmed. The centering fixed points P on the inner surface of the structure main body 5 are irradiated to check whether each centering fixed point P hits the laser beam 28, and if necessary, the winch is operated to center the ring-shaped structure 5. Adjust the position (see Figures 3 and 5).

Eleventh step: Attach the notch of the ring-shaped structure main body 5 and the hull outer plate by welding.

Twelfth step: Place the lower support member 9 and the upper support member 6 between the ring-shaped structure body 5 and the stern of the hull 1 as necessary, and use visible light to re-center the ring-shaped structure body 5. inspect,
Decide on the welding order and weld the welded parts while inspecting the core frequently.

Thirteenth step: The upper end cover 7 and the upper rear end cover 8 are mounted on the tower and welded and fixed in the same manner as in the twelfth step.

In addition, welded areas are thoroughly checked using a combination of color check and ultrasonic flaw detection.

14th step: When the construction of the ring-shaped structure main body 5 is completed as described above, the propeller shaft and the propeller 2 are assembled to their original state, and the visible light projector 27 is attached to the wing of the propeller 2 to embody the light beam. Read the difference between the centering fixed points P on the inner surface of the ring-shaped structure main body 5 and check the accuracy of the installation.

Next, the hanging pieces 12 and 13 and the centering piece 10 are removed.

As described above, in the present invention, the main body of the ring-shaped structure, the support member, and the cover are manufactured in advance, and at least the main body of the ring-shaped structure is completed, the dimensional relationship of the structure is checked, and the The feature is that positioning is performed based on a centering fixed point on the inner surface of the ring-shaped structure body that is equidistant from the centering point.

At that time, the projector is rotated around the axis of the propeller shaft, and the trajectory of the visible light is aligned with the centering fixed point on the inner surface of the ring-shaped structure that is equidistant from the center line of the propeller shaft. Therefore, the installation of the ring-shaped structure can be carried out while confirming the position with high accuracy.

If the visible light trajectory indicates the outer diameter of the propeller, it is possible to appropriately confirm the relative position of the ring-shaped structure and the propeller.

According to the present invention, most of the welding and assembly work is performed on the ground, and there are fewer on-site welding points during construction in the prefecture, so welding is easy, distortion caused by welding is small, and accuracy is improved.

In addition, there will be fewer areas to be painted on-site during construction within the prefecture, which will shorten the construction period within the prefecture.

In the above embodiment, an open stern shaped stern section was shown, but the present invention can also be applied to a closed stern shaped boat as shown in FIG.

In the present invention, as in the above embodiment, a temporary shaft may be provided in place of the propeller shaft, and the floodlight may be fixed to this, but if the floodlight is fixed to the propeller itself, members such as the propeller and rudder can be removed. Since it is not necessary, workability is good.

FIG. 9 shows a structure in which a ring-shaped structure is provided at the stern of the hull according to the present invention, and the ring-shaped structure 4 is fixed to the stern of the hull 1 in front of the propulsion device 2.

Note that 3 is the rudder. At the stern part, there is a flow Sl that rolls up from the bottom of the ship, and especially in an enlarged ship, this flow Sl is accompanied by a three-dimensional separation vortex S2.

In addition, the flow S3 that has passed through the ship side changes depending on the shape of the area near the stern of the ship, and near the stern, flow Sl and flow S3
The disturbance becomes large as a result of the complex mixing of the two.

Moreover, since the shape of the hull changes rapidly, large separated vortices S4 sometimes occur.

In this way, the flow near the stern part is highly turbulent, and the energy lost due to this turbulence of flow becomes resistance (shape resistance).

This turbulence in the flow near the stern portion is noticeable in a length range corresponding to three times the diameter Dp of the propulsion device 2.

According to the ship having the ring-shaped structure accurately centered and attached to the stern according to the present invention, the slow flow flowing on both sides of the stern is guided by the ring-shaped structure 4 and within its working plane. It is pushed out and contributes to improving propulsion efficiency.

According to the present invention, a fixed point for centering on the inner surface of the ring-shaped structure main body is irradiated with a beam of light from a projector that rotates around the center line of the propeller shaft by using the axis of the propeller shaft, The light beam of this floodlight moves on the ring-shaped structure body side so that it illuminates a fixed point for centering on the inner surface of the ring-shaped structure body that is equidistant from the center line of the propulsion shaft, and then moves the ring-shaped structure body to the stern of the ship. Since this is an attachment method, it is possible to eliminate the need for centering the projector itself by effectively utilizing the axis of the propeller shaft, and the projector, which rotates around the axis of the propeller shaft, can be positioned on the axis of the propeller shaft. Coupled with the fact that the ring-shaped structure body can be moved and fixed so that a fixed point for centering on the inner surface of the ring-shaped structure body that is equidistant from the centering point is irradiated, installation of the ring-shaped structure body is easy. In addition, the accuracy is significantly improved, and the working time during docking can be shortened.

[Brief explanation of drawings]

Figure 1 is a side view showing an example of a ring-shaped structure, Figure 2A
, B is a front view and a side view of the back of the ring-shaped structure body, FIG. 3 is a front view showing the relationship between the centering piece and the ring-shaped structure and the stern, and FIG. 4 is a front view and a side view of the back of the ring-shaped structure body. A side view of the stern showing the points, Figure 5 is an explanatory diagram for positioning a ring-shaped structure using visible light, and Figures 6A and B are visible light projectors supported at the support points of the propulsion shaft. FIG. 2 is a side view and a front view of main parts of the support device. FIG. 7 is an explanatory diagram showing a state in which a projector is provided on the propulsion device for centering. FIG. 8 is an explanatory view showing a case where a ring-shaped structure is provided at the stern of a closed stern type ship. FIG. 9 is an explanatory diagram showing the state of flow at the stern of a ship provided with a ring-shaped structure. 1...Hull, 2...Propulsion device, 3...
... Rudder, 4... Ring-shaped structure, 5...
... Ring-shaped structure body, 6 ... Upper support member, 7 ... Upper end cover, 8 ... Upper rear end cover, 10 ... Core Output piece, 12゜1
3...Hanging piece, 14...Level,
20...Temporary shaft, 21...Support arm, 23
... Stern bearing, 27 ... Laser beam projector.

Claims (1)

[Scope of Claims] 1. A light beam from a projector that rotates around the center axis of the propeller shaft illuminates a fixed point for centering on the inner surface of the ring-shaped structure body that is equidistant from the center line of the propeller shaft. A method for attaching a ring-shaped structure to the stern of a ship, characterized in that after the ring-shaped structure is moved, the ring-shaped structure is attached to the stern of the ship with reference to the central axis of the propeller shaft. . 2. The method of attaching a ring-shaped structure to the stern of a ship according to claim 1, wherein the projector is a laser beam projector.