A shipboard sealing and propeller fixing system

Abstract

A ship launching water seal shaft fixed propeller system, comprising a main engine crankshaft and a flywheel, wherein the flywheel is fixed to the main engine crankshaft by bolts, and a plurality of circular holes are arranged at equal intervals on the surface of the flywheel; a first eye plate is arranged on the left side tank bulkhead of the cabin bottom, and a second eye plate is arranged on the right side tank bulkhead of the cabin bottom, one end of a fastener is connected and fixed to the first eye plate after passing through the circular hole, one end of a nylon sling is connected and fixed to the second eye plate after passing through the circular hole, a shackle is arranged between the nylon sling and the second eye plate, and the circular hole connected to the fastener and the circular hole connected to the nylon sling are symmetrically arranged on the flywheel. The present invention invents a brand-new ship launching water seal shaft fixed propeller system based on the existing structure of the ship while retaining the original function unchanged. The invention can completely offset the torque existing in the process of launching the ship, and the strength of the system can be verified by theoretical mechanics formulas, and the fixed propeller tooling of the original fixed propeller scheme can be eliminated, simplifying the construction and processing technology.

Description

Technical Field

[0001] The invention relates to the field of ship building and ship design, and in particular to a shaft sealing and propeller fixing system used in a ship launching process. Background Art

[0002] Ship launching is the process of moving the ship from the construction area to the water after most of the ship construction project is completed. It is a very important link in the ship construction process.

[0003] Usually, during the launching process, the ship will be subjected to a large impact force, causing the main engine and propeller to rotate, which will cause serious damage to the main engine. In order to prevent damage during the launching process, a truss structure will be built in the tail area, which is what we usually call the propeller fixing tooling. The truss structure is fixed to the flywheel through 8 bolts, thereby limiting the rotation of the main engine shaft.

[0004] In order to ensure that the bracket can effectively fix the flywheel, it is necessary to analyze the strength of the bracket using the finite element method, which is time-consuming and labor-intensive.

[0005] After the ship is launched, special personnel are sent on board to dismantle and discard the propeller structure. This practice causes serious waste of manpower, materials and time. Summary of the invention

[0006] In order to solve the above problems, the present invention provides a ship launching water seal shaft fixing propeller system, which aims to completely offset the torque existing in the ship launching process and reduce the working tooling. The technical solution adopted is:

[0007] A ship launching water seal shaft fixing propeller system comprises a main engine crankshaft and a flywheel, wherein the flywheel is fixed to the main engine crankshaft by bolts, and a plurality of circular holes are arranged at equal intervals on the surface of the flywheel; a first eye plate is arranged on the left side tank bulkhead of the cabin bottom, and a second eye plate is arranged on the right side tank bulkhead of the cabin bottom, one end of a fastener is connected and fixed to the first eye plate after passing through the circular hole, one end of a nylon sling is connected and fixed to the second eye plate after passing through the circular hole, a shackle is arranged between the nylon sling and the second eye plate, and the circular hole connected to the fastener and the circular hole connected to the nylon sling are symmetrically arranged on the flywheel. The fastener and the nylon sling are arranged on both sides of the crankshaft respectively, and the fastener is arranged first and then the nylon sling is arranged in sequence along the rotation direction of the crankshaft. The fastener supports the crankshaft and prevents the crankshaft from rotating when the ship is launched. The nylon cooperates with the fastener to collect and pull the crankshaft, further preventing the crankshaft from rotating. The shackle can adjust the direction of the nylon sling when it is tightened, and the shackle is connected to the second eye plate. The nylon and the tie-down work together to ensure that the crankshaft does not rotate during the launching process of the ship.

[0008] In the above-mentioned ship launching propeller sealing system, further, a reinforcing bracket is fixed at the position of the first eye plate and the second eye plate. The reinforcing bracket strengthens the structure of the first eye plate and the second eye plate, making the eye plate and the cabin more firmly connected, thereby ensuring that the crankshaft can be pulled when the ship is launched to prevent the crankshaft from rotating.

[0009] In the above-mentioned ship launching propeller sealing system, further, the fastener and the first eye plate are selected to have a force of 5 tons, which can better ensure the structural strength between the fastener and the first eye plate.

[0010] In the above-mentioned ship launching and sealing propeller system, further, the shackle and the second eye plate are selected to have a force of 50 tons, which can better ensure the structural strength between the shackle and the second eye plate.

[0011] The above-mentioned ship launching propeller sealing system, further, has the uppermost edge of the first eye plate at a horizontal distance of 200 to 300 mm from the double bottom.

[0012] The above-mentioned ship launching propeller sealing system, further, has the uppermost edge of the second plate being at a horizontal distance of 50 to 100 mm from the double bottom.

[0013] The safety of the bolt and nylon sling of the present invention can be determined based on theoretical calculations, and the strength of the system can be checked using theoretical mechanics formulas. There are two key positions for strength checking: the shear force on the bolt and the shear force on the flywheel opening. According to theoretical mechanics theory, the shear strength is calculated as 0.58 times the yield strength.

[0014] The launching torque is T, the radius of the bolt is R, the number is n, the distance from the center is D1, the minimum cross-sectional area of ​​the flywheel structure at the force point is A, and the distance from the center is D2.

[0015] The shear strength of the bolt, the tangential force of the base circle is F1=T / D1, each bolt is subjected to the same force, the force on a single bolt is F2=F1 / n, and the shear stress of a single bolt is F3=F2 / (πR2).

[0016] According to theoretical mechanics, the shear strength is 0.58 times the yield strength, so the yield strength of the material required for the bolt at this position is M1=F3 / 0.58, and the actual yield strength of a single bolt is M2.

[0017] If M1<M2, the bolt meets the strength requirement, otherwise the bolt radius R can be increased until the requirement is met.

[0018] The shear strength at the flywheel opening is the nylon sling tension F4=T / D2, the minimum cross-sectional area of ​​the flywheel structure at the force point is A, and the shear stress at this position is F5=F4 / A.

[0019] According to theoretical mechanics, the shear strength is 0.58 times the yield strength, so the yield strength of the material required for the repositioned flywheel is M3=F5 / 0.58, and the actual yield strength of a single flywheel is M4.

[0020] If M3<M4, the flywheel structure meets the strength requirements, otherwise the minimum cross-sectional area A at the force-bearing flywheel can be increased until the requirements are met.

[0021] The present invention, while retaining the original functions, invents a new ship launching water seal shaft fixed propeller system based on the existing ship structure. The invention can completely offset the torque existing in the ship launching process, can verify the strength of the system through theoretical mechanics formulas, and can eliminate the fixed propeller tooling of the original fixed propeller solution, simplifying the construction and processing technology, improving work efficiency, and having the advantages of cost saving and high strength. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a schematic diagram of the structure of the present invention;

[0023] Figure 2 It is a side view of the structure of the present invention;

[0024] Among them: 1-main engine crankshaft, 2-flywheel, 3-bolt, 4-nylon sling, 5-tightener, 6-first eye plate, 7-reinforced toggle plate, 8-shackle, 9-second eye plate. DETAILED DESCRIPTION

[0025] The present invention will be further described with reference to the accompanying drawings. Figure 1 , 2 The shown is a ship lower water seal shaft fixed propeller system, which has a main engine crankshaft 1, and a flywheel 2 is fixed to the main engine crankshaft by bolts 3, the number of bolts is 12, and 8 circular holes are arranged at equal intervals on the surface of the flywheel. A first eye plate 6 is arranged on the left side tank bulkhead of the cabin bottom, and a second eye plate 9 is arranged on the right side tank bulkhead of the cabin bottom. One end of a 5-ton fastener 5 passes through the circular hole and is connected and fixed to the 5-ton first eye plate, and one end of a nylon sling 4 passes through the circular hole and is connected and fixed to the 50-ton second eye plate. A 50-ton shackle 8 is arranged between the nylon sling and the second eye plate, and the circular hole connected to the fastener and the circular hole connected to the nylon sling are symmetrically arranged on the flywheel. A triangular reinforcing bracket 7 is arranged below the first eye plate and the second eye plate to reinforce the first eye plate and the second eye plate. The horizontal distance between the upper edge of the first eye plate and the double bottom is 200mm, and the horizontal distance between the upper edge of the second plate and the double bottom is 50mm.

[0026] To test its safety, taking a certain oil tanker as an example, the specific implementation steps of the design method are as follows:

[0027] The water torque here is 568KN, the radius of the bolt is 28mm, the number is 12, the distance from the center is 660mm, the minimum cross-sectional area of ​​the flywheel structure at the force point is 137mm*130mm, and the distance from the center is 1212mm.

[0028] Key position 1: Connection strength between flywheel and crankshaft

[0029] The shear strength of the bolt, the tangential force of the base circle is F1=860KN, each bolt is subjected to the same force, the force on a single bolt is F2=71.7KN, and the shear stress of a single bolt is F3=29MPa.

[0030] According to theoretical mechanics, the shear strength is 0.58 times the yield strength, and the required bolt yield strength is 50.2MPa.

[0031] The actual yield strength of the bolt is 320MPa, 320Mpa>50.2MPa.

[0032] The connection strength between the flywheel and the crankshaft meets the requirements.

[0033] Key position 2: Shear strength at the flywheel opening

[0034] The tension of the nylon sling is F4=468.5KN, the minimum cross-sectional area of ​​the flywheel structure at the stress point is 17810mm2, and the shear stress at this position is 26.3MPa.

[0035] According to theoretical mechanics, the shear strength is 0.58 times the yield strength, and the yield strength of the required flywheel is 45.3MPa. The actual yield strength of the flywheel is 350MPa.

[0036] 350MPa>45.3MPa, the flywheel structure meets the strength requirements.

Claims

1. A ship water seal shaft fixed propeller system, characterized by: A main engine crankshaft (1) and a flywheel (2) are provided. The flywheel is fixed to the main engine crankshaft by bolts (3). A plurality of circular holes are arranged at equal intervals on the surface of the flywheel. A first eye plate (6) is arranged on the left side tank wall of the cabin bottom, and a second eye plate (9) is arranged on the right side tank wall of the cabin bottom. One end of a fastener (5) passes through the circular hole and is connected and fixed to the first eye plate. One end of a nylon sling (4) passes through the circular hole and is connected and fixed to the second eye plate. A shackle (8) is arranged between the nylon sling and the second eye plate. The circular hole connected to the fastener and the circular hole connected to the nylon sling are symmetrically arranged on the flywheel.

2. A ship lower water seal shaft fixing propeller system according to claim 1, characterized in that: Reinforced toggle plates (7) are fixed at the positions of the first eye plate and the second eye plate.

3. A ship lower water seal shaft fixing propeller system as claimed in claim 1, characterized in that: The fastener and the first eye plate are selected to have a force of 5 tons.

4. A ship lower water seal shaft fixing propeller system as claimed in claim 1, characterized in that: The shackle and the second eye plate are selected to have a force of 50 tons.

5. A ship lower water seal shaft fixing propeller system as claimed in claim 1, characterized in that: The horizontal distance between the uppermost edge of the first eye plate and the double bottom is 200-300 mm.

6. A ship lower water seal shaft fixing propeller system as claimed in claim 1, characterized in that: The horizontal distance between the uppermost edge of the second eye plate and the double bottom is 50-100 mm.

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