Relocatable Positioner Assembly for Overhead Crane Precision
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Solution Overview
Problem
Overhead cranes lack the ability to accurately position and hold objects due to their vertically extending wire ropes, which provide little resistance to lateral loads and overturning moments, making it impractical for tasks like fabrication and assembly.
Innovation Solution
A detachable and relocatable positioner system for overhead cranes, featuring a frame with multiple hoists and ropes that support a lower member, allowing secure attachment to the crane's bridge or platform, and includes locking and aligning devices for precise positioning and holding of objects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single hoist with vertically extending wire rope is used for lifting, then the crane structure is simple, but the positioning accuracy and ability to resist lateral loads deteriorates
Solution Approach 1:
The lifting system is divided into two independent subsystems: a single hoist for vertical lifting and a positioner assembly with multiple hoists for lateral positioning. This segmentation allows each subsystem to specialize in its function, maintaining simple lifting while adding precise positioning capability.
Solution Approach 2:
The positioner assembly acts as an intermediary device between the single hoist and the workpiece. The positioner receives the lifted workpiece and provides fine positional adjustments, mediating between the crude vertical lift and the requirement for precise positioning.
2Device complexity
If vertically extending wire ropes are used for lifting, then the lifting mechanism is simple, but the ability to resist lateral loads and overturning moments deteriorates
Solution Approach 1:
The support system is segmented into vertical support (single hoist) and lateral support (positioner with multiple hoists). This separation allows the lifting mechanism to remain simple while the positioner provides dedicated lateral load resistance through its multi-point suspension geometry.
Solution Approach 2:
The positioner assembly introduces lateral dimensional support by positioning multiple suspension points at different horizontal locations. This creates a three-dimensional support structure that resists lateral loads and overturning moments, whereas the single vertical rope only provides one-dimensional support.
3Measurement precision
If additional positioning devices are added to achieve accurate positioning, then the positioning accuracy improves, but the device complexity increases
Solution Approach 1:
The positioner assembly is designed as a multi-functional device that combines lifting support, lateral positioning, and fine adjustment capabilities in one unit. This universality avoids the need for multiple separate devices, limiting the increase in overall system complexity.
Solution Approach 2:
The positioner assembly is designed to be movable and relocatable along the bridge, allowing it to be dynamically positioned where needed. This dynamic capability provides flexible positioning without requiring fixed complex positioning infrastructure throughout the entire workspace.
4Adaptability or versatility
If the positioner is made relocatable and detachable, then the adaptability improves, but the ease of operation deteriorates
Solution Approach 1:
The positioner assembly is designed to be self-contained with integrated locking and alignment features that automatically engage when positioned correctly. This self-service design reduces the operational complexity of attachment and detachment, making the system easier to relocate despite its versatility.
Data Source
AI summary
A method and apparatus is provided for at least holding an object with a crane having a bridge spanning between and movable on the spaced apart rails, an upper platform movable longitudinally on the bridge, and a hoist mounted to the platform, the hoist having a rope and a lifting member disposed at a remote end of the rope. The method includes engaging and moving a positioner to a selected location on the bridge or the upper platform using the hoist; securing the positioner to the bridge at the selected location or the upper platform; securing the positioner to an object; holding the object with the positioner; releasing the object from the positioner; releasing the positioner from the bridge or the upper platform; and engaging and moving the positioner away from the selected location on the bridge or the upper platform using the hoist.