WO2004092004A1

WO2004092004A1 - Marine vessel having lateral bending buffering bow

Info

Publication number: WO2004092004A1
Application number: PCT/JP2004/005373
Authority: WO
Inventors: Hisayoshi Endo; Yasuhira Yamada
Original assignee: National Maritime Research Institute
Priority date: 2003-04-17
Filing date: 2004-04-15
Publication date: 2004-10-28
Also published as: JP2004314825A; JP3899406B2

Abstract

A marine vessel having a buffering bow allowing considerable effect to be expected merely by rather simple machining, wherein a low strength part for lowering the lateral bending strength of a bulb is formed in the shell of a bulbous bow at the base part of the bulb. The low strength part is formed of a low yield point steel. Thus, the depth of a damage to the hull of a mating vessel in collision can be reduced, and the hull can be prevented from being burst to prevent a cargo leakage accident.

Description

Description Technical field of ships with side-bend shock absorbing bow

The present invention relates to a ship having a spherical bow (Palpasbau) for reducing wave making resistance. In particular, it relates to ships that can minimize damage to the other ship when colliding with another ship and contribute to the prevention of marine pollution accidents due to oil spills. Background art

Conventionally, the bow of a ship has not been designed with a cushioning effect in case of collision with another ship. Recently, however, there has been an ever-increasing number of accidents involving leakage of freight oil from colliding oil tankers, and there is an increasing demand for bows with a buffering effect, especially for ships with a spherical bow (Barbasbau). As an example of this conventional technique, for example, Japanese Patent Application Laid-Open No. 8-1648787 (FIGS. 1 to 3; referred to as Patent Document 1 in the following description) can be cited.

FIG. 3 (A) is a longitudinal sectional view of a main part of a collision energy absorbing spherical bow disclosed in Patent Document 1, and FIG. 3 (B) is a cutaway view taken along the line A—A of FIG. 3 (A). It is. FIG. 3 (C) is a horizontal cross-sectional view showing the crushed state of the valve at the time of the collision.

FIGS. 3 (A) and 3 (B) show a valve 11 projecting forward from the watertight horizontal bulkhead 12 at the forward end of the bow. The valve 11 has a water-tight tip wall member 13 arranged so as to form a valve tip surface, and a hull shell 1 near the water-tight horizontal partition wall 12 at the periphery of the tip wall member 13. And a peripheral wall portion for absorbing energy connected to the peripheral portion.

In this collision energy absorbing spherical bow, as can be seen from Fig. 3 (C), when an accident occurs in which the bow valve collides with the side of another ship, It is trying to minimize the occurrence of a breach in another ship by absorbing the collision energy and crushing the surrounding wall as the non-pressure-resistant shell of the valve. Disclosure of the invention

Patent Document 1 above is considered to be one of the leading proposals for a shock-absorbing bow.

An object of the present invention is to provide a ship having a shock-absorbing bow that can be expected to have a considerable effect even with relatively simple work.

In order to solve the above-mentioned problems, a ship having a transverse bending type bow according to the present invention is a ship having a spherical bow (Palbas bow), wherein the outer plate at the root of a spherical projection (valve) in the Balbas bow has A low-strength portion is provided for lowering the bending strength in the lateral direction of the valve, and the low-strength portion is provided with a lower yield point or a low yield point steel having a 0.2% proof stress of not more than 235 MPa. It is characterized by consisting of

In a ship having a side-bend shock-absorbing bow according to the present invention, even when a ship collides with another ship, the bow of the own ship is bent by the reaction force of the collision, so that the bow (valve) of the own ship is provided on the side of the other party. The hull can be prevented from being damaged, and damage to the hull of the other party can be minimized.

• The lateral bending strength is the bending strength in the horizontal direction with respect to the ship's tail line. The root part of the valve means the part where the valve is attached to the hull body and the part slightly ahead of it.

It is preferable that the bending strength in the vertical direction of the valve is not reduced as much as possible. BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a diagram showing a portion of a valbass bow of a side-bending buffer type bow according to one embodiment of the present invention.

(A) It is a side view.

(B) It is a front sectional view of B_B of (A).

(C) It is a horizontal sectional view of C-C of (A). Fig. 2 is a perspective view showing the situation in which the bow (valve) of one's own ship is deformed when the Barbasbau shown in Fig. 1 collides with the side (not shown) of another ship.

(A) shows the situation before the collision.

(B) shows the situation when a collision occurs.

Fig. 3 shows the main part of the collision energy absorbing spherical bow disclosed in Patent Document 1.

(A) It is a longitudinal cross-sectional view of a main part of a bow.

(B) It is sectional drawing in the AA direction of (A).

(C) It is a horizontal sectional view which shows the valve crush state at the time of the collision of the Barbas-bow structure of (A) corresponding to (B). BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, this will be described in more detail with reference to the drawings.

FIG. 1 and FIG. 2 are views showing a balbus bow portion of a side-bend buffer type bow according to one embodiment of the present invention.

Fig. 1 (A) is a side view, Fig. 1 (B) is a front sectional view of B-B in Fig. 1 (A), and Fig. 1 (C) is C_C in Fig. 1 (A). FIG. FIG. 1 (C) also shows a flank 5 of another ship colliding with the valve 1 at a collision angle f slightly deviated from a right angle.

FIG. 2 is a perspective view showing a situation in which the bow (valve) of the own ship is deformed when it collides with the side (not shown) of another ship.

Figures 1 (A) and 1 (C) show a valve 1 for reducing wave making resistance, which protrudes forward from the bottom of the bow. The bulb 1 has an oval vertical section and a dome shape protruding toward the front end. In the valve 1, ring-shaped horizontal rib members 3a to 3d are attached in order to reinforce the valve outer plate 4 forming the body of the valve 1 from the inside. The transverse rib members 3a to 3d are arranged at substantially equal intervals in the front and rear directions of the hull.

Near the horizontal rib member 3a and the horizontal rib member 3b closest to the base of the valve 1, A low-strength portion 2 for reducing the bending strength in the lateral direction of the valve 1 is formed.

As shown in FIG. 1, the low-strength portion 2 is a rectangular portion disposed on both side surfaces of the valve outer plate 4 so as to be parallel to the transverse rib members 3a and 3b. The low-strength portions 2 are arranged on the left and right sides in an elliptical center distribution in the front cross-section of the valve 1 at BB (see FIG. 1 (B)).

The low-strength section 2 is not provided at the upper part (ceiling) or lower part (bottom) of the valve 1. This is because the longitudinal (vertical) bending strength of the valve 1 is not desired to be reduced.

Hereinafter, a numerical example of the low strength portion 2 will be described. In the low-strength section 2, the center of the width is located almost in the middle between the transverse rib members 3a and 3b, and the length of one side is about two-thirds of the half circumference of the ellipse. The width of the low-strength part is 700 mm, and the thickness is 9 mm, which is the same as the valve outer plate 4.

Also, the overall length of the valve 1 is 2300 mm, the pitch of the horizontal rib members 3 a to 3 d is 550 mm, and the cross section of the valve 1 is taken along the line BB (see the cross section with the low strength part 2, see Fig. 1 (B)). When the long side of the elliptical shape is 3200 mm and the short side is 1250 mm, the section modulus of the low strength part 2 is 2.2 × 10 ⁴ cm ³ .

In this example, the low-strength portion 2 is formed of a low-yield-point steel (also called an extremely mild steel). Low yield point steel is a steel material that has a low carbon equivalent (for example, less than 0.01%) and a lower yield point or 0.2% resistance than ordinary mild steel.

Examples of low yield point steel materials are shown in Tables 1, 2 and 3 below. Table 1. Chemical composition

(ma ss%) Remarks 1. If necessary, alloying elements other than the above can be added, 2. Add elements such as A1 that fix N. If free N is 0.006% or less, N can be added to 0.009%. Table 2. Carbon equivalent or weld crack susceptibility composition

Carbon equivalent (%) = C + Mn / 6 + Si / 24 + Ni / 40 + Cr / 5 + Mo / 4 + V / 14

Weld crack susceptibility composition (%) = C + Si / 30IMn / 20 + Cu / 20 + Ni / 60 + Cr / 20 + Mo / 15 + V / 10 + 5B Table 3. Lowering yield point or resistance, yield ratio and Growth

Remarks 1. The test piece shall be the specified value in the direction perpendicular to the rolling direction (C direction).

2. Yield ratio = (falling point or resistance to resistance / tensile strength) XI 00 On the other hand, other parts of the valve outer plate 4 are, for example, mild steel such as JIS SS400, and the yield stress is, for example, about 340 N. a / mm ^2.

In this case, the cross section of the low-strength portion 2 (cross section taken along the line B—B of the valve 1) starts yielding (bending) in response to a lateral bending moment. Since it is expressed as the product of stress

(1) When the low strength part 2 is made of low yield point steel LY100 (yield stress = about 10 ONZmm ² )

: M = 2.2 MN · m

(2) When low strength part 2 is mild steel SS400

: M = 7.5 MN · m It becomes.

When the low-strength portion 2 is made of low-yield-point steel, plastic deformation (bending) starts with a lateral bending moment of about 30%, compared to the case of using the same mild steel as the valve shell 4. Will do. This has the effect of making it easier for the own bow (valve 1) to bend at the collision reaction force P (see Fig. 1 (C)) when colliding with another ship.

FIG. 2 is a simulation result of the deformation state of the valve 1 when the valve 1 collides with the side 5 of another ship at a collision angle f of 70 degrees in the above embodiment. As shown in Fig. 2 (B), the valve 1 is bent starting from the low-strength part 2, and it is expected that the valve will not be easily incorporated into the other ship that collided.

If the bent valve 1 has a certain size, it will come into contact with the other party's flank with a large contact area in the event of a collision. In this case, even if the damage area increases, the collision reaction force per unit area can be kept small, so that the damage depth of the opponent's flank can be reduced and also a hole can be prevented.

In this example, as shown in Fig. 1 (B), the low-strength part 2 is arranged at the center of the ellipse, and the length of one side of the low-strength part 2 is one-third of the half circumference of the ellipse. By setting the value to 2, the vertical strength of the valve 1 against vertical wave impact force and the like can be ensured without significantly lowering the bending strength in the vertical direction (vertical direction) of the valve 1.

According to the above operation, in the embodiment of the present invention, the strength of the pulp 1 against the wave impact force in the vertical direction (vertical direction) is secured, the depth of damage to the flank of the other party during the collision is reduced, and Holes can be prevented. If the other ship is a dangerous goods carrier such as an oil tanker, a ship with a side-bend shock-type bow with the advantage of preventing cargo leakage accidents can be provided. The invention's effect

As is apparent from the above description, according to the present invention, at the time of a collision, the bow of the own ship bends due to the collision reaction force, thereby reducing the depth of damage to the flank of the other party, and at the same time, preventing perforations and preventing cargo A ship having the advantage of preventing a leak accident can be provided.

Claims

The scope of the claims

1. A ship with a spherical bow (Barbasbau),

A low-strength portion for reducing the lateral bending strength of the valve is provided on the outer plate at the root of the spherical projection (bulb) of the pulsus bow. A ship having a transverse bending shock-type bow made of low yield point steel having a 2% proof stress of not more than 235 MPa.