Pretension and lay-off method and device of crane jib for ship

Abstract

The invention relates to a pretension and lay-off method of a crane jib for a ship, belonging to the technical field of a crane. The crane comprises a luffing mechanism composed of a top pulley block, a jib, a winch, a luffing wire rope and a jib head pulley block and a bracket. The method comprises the following steps: A. operating the winch in the forward direction, loosening the jib and layingoff the jib onto the bracket; and B, operating the winch in the reverse direction, pulling the jib upwards to enable the pressure of the jib on the bracket to be less than the pressure on the bracketbefore being subjected to the upward pull, and stopping and shutting off the winch. The invention also relates to a pretension and lay-off device of a crane jib for a ship. The luffing mechanism alsocomprises a middle pulley arranged at the middle of the jib, and the luffing wire rope is connected with the jib head pulley block and the middle pulley through the top pulley block. The pretension and lay-off method and device of a crane jib for a ship can produce a pretension force on the jib by means of the luffing wire rope, thereby reducing the self-weight load of the jib as well as the influence and the destruction on the jib structure as a result of the shock load and the changing load of the bracket on the jib. Besides, the invention has the advantages of simple method and structure, convenient operation and low cost.

Description

Technical field [0001] The invention relates to a marine crane, in particular to a method and device for pre-tensioning and placing a boom of a marine crane, belonging to the technical field of cranes. Background technique [0002] When the existing marine crane is in a non-working state, the boom is down and placed on a bracket fixed on the hull. At this time, the boom is a bending member supported by two points and bears the bending moment generated by its own gravity. Different from land cranes, the boom of marine cranes not only bears the static load of the boom’s own gravity, but also needs to bear the impact load and alternating load generated by the ship's hull turbulence during sailing. At this time, the boom is prone to impact damage and fatigue. Damage, especially when a hurricane at sea causes a huge turbulence of the hull at a wind speed of 55 meters per second, the boom often needs to bear a load equivalent to or even higher in the working state. For the small hull a...

AI Technical Summary

Problems solved by technology

[0004] The first object of the present invention is to overcome the defects and deficiencies of the prior shelving method of the arm of a marine crane, which are easily caused by impact damage and fatigue damage due to the impact load and alternating load generated by the turbulence and sway of the ship, and provide a A method for preloading and shelving the boom of a marine crane can effectively reduce the impact damage and fatigue damage and damage to the hull caused by the shock load and alternating load borne by the boom due to the pitching and shaking of the hull, and can significantly reduce the damage to the boom of the crane at the same time. The bending moment generated by the self-weight in the shelving state improves the stress of the boom, reduces the self-weight of the boom structure, and prolongs the service life of the boom, crane and even the ship

[0005] The second object of the present invention is to overcome the large bending moment and deformation caused by the self-weight of the boom existing in the shelving device of the existing marine crane boom in the shelving state, and to withstand the shock load and alternating load generated by the pitching and shaking of the ship body easily. Defects and deficiencies that cause impact damage and fatigue damage, provide a pre-tightening shelving device for the boom of a marine crane, so that the boom can bear upward tension when it is in the shelving state, thereby significantly reducing the bending moment and deformation caused by the self-weight of the boom, At the same time, it significantly reduces the alternating load and impact load acting on the boom, as well as the resulting fatigue damage and impact damage, and has a simple structure, convenient operation and good safety.

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