Jib Crane Conversion Device for Load Positioning

Solution Overview

Problem

Jib cranes in shipbuilding yards face issues with positional displacement and dragging of heavy burdens due to jib tilting during lift-off and landing, affecting centering efficiency and safety.

Innovation Solution

A conversion device on the revolving table that converts the load from hoisting wire ropes into a lead-in motion of derricking wire ropes, using a pivotable link and stopper mechanism to maintain the burden's position on a plumb line and prevent dragging, by adjusting the derricking angle of the jib.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the jib is held at a predetermined upward derricking angle to the horizontal, then the burden can be lifted off, but the tip of the jib tilts forward due to bending causing positional displacement of the hanged burden

Engineering Contradiction:

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The conversion device performs preliminary action by converting the load from hoisting wire ropes into lead-in of derricking wire ropes before the burden is lifted. This anticipates the jib bending and compensates for it by adjusting the derricking angle in advance, ensuring the burden remains on the plumb line throughout the lifting process.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The conversion device acts as an intermediary mechanism between the hoisting system and derricking system. It transfers and converts the load effect from hoisting wire ropes into lead-in motion of derricking wire ropes, mediating the interaction between lifting and positioning functions to eliminate positional displacement.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Ease of operation

If the burden is landed and load is released, then the jib returns to original position, but the burden is dragged toward the base end of the jib

Engineering Contradiction:

Core Design Contradiction:

Ease of operationVSManufacturing precision

Solution Approach 1:

The conversion device performs preliminary action by converting the load from hoisting wire ropes into lead-in of derricking wire ropes before the burden is lifted. This anticipates the jib bending and compensates for it by adjusting the derricking angle in advance, ensuring the burden remains on the plumb line throughout the lifting process.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The conversion device acts as an intermediary mechanism between the hoisting system and derricking system. It transfers and converts the load effect from hoisting wire ropes into lead-in motion of derricking wire ropes, mediating the interaction between lifting and positioning functions to eliminate positional displacement.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Force

If the jib bends under load, then the burden can be supported, but centering efficiency deteriorates and safety is compromised

Engineering Contradiction:

Core Design Contradiction:

ForceVSProductivity

Solution Approach 1:

The conversion device acts as an intermediary mechanism between the hoisting system and derricking system. It transfers and converts the load effect from hoisting wire ropes into lead-in motion of derricking wire ropes, mediating the interaction between lifting and positioning functions to eliminate positional displacement.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The conversion device dynamically changes the derricking angle parameter in response to load variations. By converting load into lead-in of derricking wire ropes, it adjusts the derricking angle to compensate for jib bending, maintaining positioning precision while supporting heavy loads.

Inventive Principle:

Principle #35Parameter changes

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This solution ensures accurate positioning and safety of heavy burdens by compensating for jib tilting during lift-off and preventing dragging during landing, thereby improving centering efficiency and ensuring safe handling.

Implementation Method 1

load of the burden applied to the hoisting wire ropes causes the conversion device, more specifically the link, to be pivoted in the one direction. This pivotal movement pulls the derricking wire ropes to lift the jib upwardly

Methodology Applied

Scientific EffectForce transmission and conversion: Mechanical Force

Implementation Method 2

a stopper adjacent to the revolving table for preventing the link to be pivoted in the other direction upon contact with the link

Methodology Applied

Scientific EffectMechanical constraint: Mechanical Force

Implementation Method 3

a jib pivoted on a revolving table for derricking motion

Methodology Applied

Scientific EffectPivotal rotation: Friction

Data Source

PatentUS8141725B2Jib crane

Publication Date: 2012.03.27

AI summary

A jib crane which can prevent an unexpected movement of a burden and can sufficiently ensure the safety of a burden handling work is disclosed. The jib crane has hoisting wire ropes for lifting and landing a hook, derricking wire ropes for derricking operation of a jib, and a conversion device for fixing tips of the wire ropes to a revolving frame of a revolving table. The conversion device has a V-shaped link pivotally supported on a bearing bracket via a pivot pin. The tips of the wire ropes are connected to paired link arms of the V-shaped link.