JPS5855033B2 - How to fix a ring-shaped structure to the stern of a ship - 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 the stern of a ship in front of a propulsion device.

As ships become larger, the flow of water near the stern and the unevenness of the sales floor increase the force required for propulsion.
It is known that vibration and noise increase.

Figure 1 shows the state of the sales floor in the stern section of an enlarged ship. 1 is the hull, the stern is equipped with a propeller 2 and a rudder 3,
A cruiser stern 1a is formed above these.

As shown in the figure, the flow in the stern section is accompanied by a three-dimensional separated vortex S2 relative to the flow Sl that rolls up from the bottom of the ship.

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 the flow S1 and S
The disturbance becomes large as 3 collide in a complicated manner.

Further, near the cruiser stern portion 1a, the shape of the hull changes rapidly, resulting in large separated vortices S4 at times.

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

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

Figure 2 shows an example of the wake distribution of an enlarged ship, and shows that the slow flow, that is, the flow at or near w=1, is not concentrated within the range of the circle Dp that represents the operating surface of the thruster. Recognize.

The present inventors grasped the characteristics of the sales floor near the stern,
As a result of considering ways to improve this and reduce the horsepower required for propulsion and reduce vibration and noise, we found that a position in front of the propulsion unit that does not overlap with the propulsion unit when viewed from the side, preferably slightly at the stern. It has been confirmed that it is preferable to provide the ring-shaped structures so as to match each other, and many proposals have already been made regarding this invention.

Figure 3 shows a ship equipped with a ring-shaped structure at the stern.
is collected and supplied to the working surface of the thruster 2.

As shown in Figure 2, there is a slow current on both sides of the stern.
The ring-shaped structure 4 receives this and pushes it into the working surface of the thruster.

The shape is preferably circular, arranged evenly on both sides, but can be modified into an ellipse or other shape depending on the flow conditions at the stern.

The ring-shaped structure may be attached by welding directly to the stern, or by welding a support member between the ring-shaped structure and the stern.

The shape of the ring-shaped structure (different depending on whether it is an open stern or a closed stern) and the structure of the attachment part vary depending on the size of the ship, etc., but its dimensions are, for example, approximately 25,000 mm.
In the case of a 0 ton tanker, the ring-shaped structure has an inner diameter of about 900 crrL, a width of about 450 cm, and a weight of about 9 Q ton.

As mentioned above, the ring-shaped structure is large and heavy, but depending on its dimensional accuracy and installation accuracy, the effect of installing the ring-shaped structure may be negative, so it is necessary to improve the installation accuracy. It is very important to do so.

On the other hand, when installing such a structure, the propulsion device, propulsion shaft,
The rudder and related parts interfered with the work, so it was necessary to remove them.

In particular, in order to avoid deterioration in the accuracy of the ring-shaped structure, when transporting the completed product into a dock and fixing it, it is necessary to remove at least the propulsion device and propulsion shaft, which is an extremely difficult and time-consuming task. required man-hours.

Therefore, it is extremely important and desirable to simplify the method of attaching the ring-shaped structure.

As mentioned above, in order to avoid the disadvantages of fixing an integral ring-shaped structure to the stern, it is also possible to divide the Su/Nobo structure into multiple parts and assemble them one after another in the dock. It is conceivable that this method would require more on-site welding, and as a result, welding distortion would inevitably increase.

In addition, because the installation procedure for the ring-shaped structure becomes complicated,
This has the disadvantage that both the precision of the ring-shaped structure itself and the precision of its installation are reduced.

In order to eliminate the above-mentioned drawbacks, we have made extensive studies and completed the present invention.

That is, the present invention is a method for fixing a ring-shaped structure having a notch for fitting into a ship's hull to a stern part of a ship in front of a propulsion device, the ring-shaped structure being fitted to the ship's hull in advance. A circular arc-shaped main body portion having a cutout portion for the purpose of cutting and a remaining main body portion having no cutout portion are separately formed, and then these main body portions are temporarily assembled and centered;
Next, the temporarily assembled ring-shaped structure is divided into two parts before being temporarily assembled, and then the main body part having the cutout part is fixed to the stern part of the hull, and then the remaining part is fixed to the previously attached main body part, At that time, a visible light emitter is installed on the advance device,
The feature is that this propeller is rotated to irradiate a designated point provided on a ring-shaped structure for centering.

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

First step: First, the case of a ring-shaped structure to be attached to a vessel having an oven stern shape at the stern will be described.

A ring-shaped structure is placed on the ground, manufactured separately into the following parts, and the parts that can be assembled are assembled.

The disassembled parts are as follows. (See Figures 4 and 5) (1) Arc-shaped ring-shaped structure body having a notch 26...10A (2) Remaining ring-shaped structure attached to the ring-shaped structure body 10A Object body...l0B (3) Body cover plate (top)...11 (4) Body cover plate (bottom)...12 (5) Upper support member...
...13 (6) Upper end cover ...14 (7) Upper rear end cover ...15 (8) Lower support member ...16 (closed stern type) (This member can be omitted in this case.) All of the above members have been assembled, welded, and painted, except for some construction holes.

Second step: On a surface plate, the ring-shaped structure main body 10A and the main body 10B are assembled, temporarily attached, and after marking, the two main bodies are overlapped and the accuracy of shape and size is inspected.

Third Step FIG. 5 is a front view of the main body of the ring-shaped structure. Temporary supports 17 and 18 are provided on the inner diameter side of each main body to prevent it from being deformed during transportation.

4th step As shown in Fig. 5 (temporarily attached ring-shaped structure body 10A)
, 10B, the center line of the propeller shaft (M-B) P,
(M-B)S, (M-A)U, (M-A)L.

Fifth step Eight steel centering pieces 19 are manufactured, and the intersection of the center of each piece 19 with the circle 21 centered on the propeller shaft 20 is determined on the drawing, and that point is placed on the ring-shaped structure body. Measure from the inside and warp it onto each piece, then attach it to the inside of the ring-shaped structure body.

Note that the centering piece 19 may be fixed inside the ring-shaped structure main body, and a point passing through the outer diameter of the propeller 2 may be provided on the centering piece 19.

(There are cases where the circle 21 and the line passing through the outer diameter of the thruster 2 are the same, and cases where they form concentric circles.) 12 pieces of the 6th stroke hanging piece 22 are fixed, and 8 pieces of the hanging piece 23 are each placed. Attach it to the outer periphery and back of the ring-shaped structure body as shown in Figs. 4 and 5.

Through the above steps, marks are placed on the ring-shaped structure at the necessary locations, dimensional accuracy is confirmed, and the ring-shaped structure is ready for lifting.

Temporarily attached parts 24 and 25 of the seventh ring-shaped structure main body 10A and 10B
Remove the temporary attachment.

8th process Next, as shown in Figure 1, the front end line (MC) of the designed ring-shaped structure is predetermined on both sides of the hull outer plate.
Gagaku.

Ninth process The center line of the thruster shaft 20 (
M-D) using a spirit level.

1st O step: Distort the intersection M-2 of the outer inner diameter of the ring-shaped structure main body on the hull outer plate centerline and the intersection M-1 between the hull outer plate centerline and the hull keel line.

Eleventh Step A winch, pulley, rigging, etc. are placed near the stern, and the ring-shaped structure main body 10A is carried into the dock and placed at a predetermined location on the stern.

At this time, the ring-shaped structure main body 10A is accurately positioned by aligning the marking lines at each position described above.

For example, the alignment order is as follows.

a. Align the line M-1 marked on the hull outer plate with the front end of the ring-shaped structure main body 10A.

60 points M-2 are located on the line (M-A')U.

C1 Point M-1 is located on the line (M-A)L (Fig. 5).

d. Connect the rear ends of line (M-A')U and line (M-A)L with a vertical line, and confirm that there is a plumb line on the extension of point M-1.

(FIG. 6) FIG. 8 shows the process of attaching the ring-shaped structure bodies 10A and 10B to the stern section 1 of the hull.

As shown in FIGS. 1 to 4, a ring-shaped structure main body 10
A is sent toward the center from the sides of the stern section, and in the process shown in FIG.

Twelfth Step A visible light (hereinafter referred to as visible light) emitter 27 such as a laser beam is fixed to the propulsion device 2 or a member provided on the propulsion device or the propulsion shaft 20.

(Figure 10) Step 13: Rotate the propeller 2 and check whether the trajectory of visible light emitted from the light emitter 27 passes through the circle 21 in Figure 6 and matches the marking line on the centering piece 19. If necessary, operate the winch and use the notch 26 of the ring-shaped structure main body 10A to adjust the position.

14th step Next, as shown in step 5 of FIG. 8, the notch 26 of the ring-shaped structure main body 10A and the stern part 1 are fitted, and the fitting portion is welded.

Step 15: Mount the lower support member 16 and upper support member 13 shown in FIG. Welding will be carried out while conducting inspections.

In the 16th step, the ring-shaped structure body 10B is mounted on the tower, temporarily attached, and the attachment position of the ring-shaped structure body 10B is adjusted to be as accurate as possible with respect to the core using visible light.

(Step 5 in FIG. 8) Step 17: While frequently inspecting the core of the ring-shaped structure body 10B, welding is performed on the ring-shaped structure body 10A.

(Step 6 in Figure 8) Main body cover plate (top), (bottom) IC that covers the 18th step welding location
Weld l3.

(FIG. 4) Step 6 in FIG. 8 shows this state, and points 24 and 25 in FIG. 5 are the welding points in this step.

FIG. 9 shows the joint part (upper part) of the ring-shaped structure main body 10A and the main body 10B, and the chill play) 28, 29 protrudes from the main body 10A and the main body 10B, respectively.
After supporting the cover plate 11 with these, the cover plate 11 is welded to the surface plates of the main body 10A and the main body 10B.

Note that 30.degree. 31 is a reinforcing rib provided between the surface plate and the inner surface plate of the main body.

19th step: Mount the upper end cover 14 and the upper rear end cover 15, temporarily attach them, inspect the core with visible light, decide the welding order, and weld the water while inspecting the core frequently. do.

In the 20th step, the welded parts at the installation site are completely inspected by a combination of color check and ultrasonic flaw detection.

Once the ring-shaped structure has been attached to the stern of the ship as described above, slowly rotate the propulsion device again and read the difference between the light beam from the light emitter 27 and the marking line on the centering piece 19. , check the installation accuracy.

21st step Remove hanging pieces 22, 23 and centering piece 19,
Areas damaged by construction will be repainted.

In the present invention, the ring-shaped structure can be fixed without removing the propulsion device 2, rudder 3, and related members in the stern section, or without touching the hull structure, and while checking the core. This installation is extremely easy.

That is, the present invention is a method for fixing a ring-shaped structure having a notch for fitting into a ship's hull to a stern part of a ship in front of a propulsion device, the ring-shaped structure being fitted to the ship's hull in advance. Arc-shaped main body portion 1 having a notch 26 for
0A and the remaining main body portion 10B that does not have a notch, and are formed separately, and then these main body portions 10A,
10B is temporarily assembled and centered, then the temporarily assembled ring-shaped structure is divided into two in the state before temporary assembly, the main body portion 10A having the notch 26 is fixed to the stern of the hull, and then the remaining Main body part 1 with part 10B installed first
Fixed at 0A, at that time, the visible light emitter 27 is attached to the propeller 2.
Since the thruster 2 is rotated to irradiate and center the designated points provided on the ring-shaped structure, installation accuracy is required in the same manner as when fixing the integral ring-shaped structure body. Not only can it be maintained, but the manufacturing and installation man-hours are also relatively small.

In particular, in the present invention, the core around the propeller shaft can be confirmed using visible light without removing the propeller, etc., so the work is simple and the ring-shaped structure can be easily removed without having to hold it. The installation accuracy is extremely good.

In addition, there are few on-site welding and painting locations throughout the prefecture, so
The construction period during construction can be shortened.

In the above embodiments, a ship with an open stern structure has been described, but the present invention is not limited to this. (In this case, the present invention can also be implemented on a ship with a closed stern structure as shown in FIG. 11.) In this case, the lower support member shown in FIG. 4 can be omitted.

Further, in this case, since there are two notches, the positioning effect of the ring-shaped structure is further improved.

[Brief explanation of drawings]

Figure 1 is a diagram showing the flow state in the stern of an enlarged ship, Figure 2 is a flow velocity distribution diagram of the ship shown in Figure 1, and Figure 3 is a ring-shaped structure installed in the stern in front of the propulsion device. FIG. 2 is a diagram showing the flow state of ships. 4 to 9 show embodiments of the present invention, and FIG. 4 is a side view showing the relationship between the ring-shaped structure and the stern;
Figure 5 is a front view of the ring-shaped structure body, Figure 6 is a front view showing the centering state of the ring-shaped structure body, Figure 7 is a side view showing the shape of the stern part, and Figure 8 is the stern. FIG. 9 is a plan view showing the order in which the ring-shaped structure is fixed to the ring-shaped structure, FIG. 9 is a structural diagram of the joint portion of the ring-shaped structure, and FIG. 10 is an explanatory diagram of the centering situation using visible lines. FIG. 11 is a side view of a ring-shaped structure attached to the stern of the closed stern. 1...Hull, 2...Propulsion device, 3...
... Rudder, 4... Ring-shaped structure, 10A, B
... Ring-shaped structure main body, 13 ... Upper support member, 16 ... Lower support member, 17, 1
8...temporary support material, 19...centering piece, 20...propeller shaft, 21...outer diameter of the propeller or for centering Circle, 27... Visible light emitter.

Claims (1)

[Claims] 1. A method for fixing a ring-shaped structure having a notch for fitting into the ship's hull to the stern of the ship in front of the propulsion device, which method involves fitting the ring-shaped structure to the ship's hull in advance. An arc-shaped main body portion 10A having a notch 26 and a remaining main body portion 10B having no notch are formed separately, and then these main body portions 10A and 10B are temporarily assembled and centered. Then, the temporarily assembled ring-shaped structure is divided into two parts before being temporarily assembled, and then the main body part 10A having the notch 26 is fixed to the stern part of the hull, and then the remaining part 10B is attached to the previously attached main body. Fix it to part 10A,
At that time, a visible light emitter 21 is provided on the propulsion device 2, and the propulsion device 2 is rotated to illuminate a designated point provided on a ring-shaped structure for centering. How to fix a ring-shaped structure.