Oblong Arcuate Locking Holes for Crane Boom Positioning
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Solution Overview
Problem
Existing tilting jib crane locking systems require precise manual alignment and significant force for secure locking and unlocking, leading to impracticality and susceptibility to human error.
Innovation Solution
The use of oblong arcuate locking holes on a locking plate integrated with the drum, combined with controlled motor operations to align and engage a lock within these holes, allowing for secure locking and easy unlocking with reduced manual intervention.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If circular locking holes are used with precise alignment requirement, then locking reliability is improved, but operation complexity and human error susceptibility increase
Solution Approach 1:
The locking holes are changed from circular to oblong arcuate shape, modifying the geometric parameters to provide both radial and circumferential play. This shape transformation allows the lock to engage reliably while accommodating alignment tolerances and reducing manual intervention requirements.
Solution Approach 2:
The locking hole is divided into functional zones: a radial engagement portion for secure locking and a circumferential portion for alignment tolerance. This segmentation allows the lock to engage radially while permitting circumferential movement during alignment, resolving the contradiction between reliability and ease of operation.
2Strength
If high force is required for lock engagement, then locking strength is improved, but ease of operation deteriorates requiring manual intervention
Solution Approach 1:
The locking system transitions from a static high-force engagement to a dynamic progressive engagement. The oblong arcuate shape allows the lock to engage progressively as the drum rotates, converting the high instantaneous force requirement into a lower sustained force over a longer engagement distance, thereby improving ease of operation while maintaining locking strength.
Solution Approach 2:
The oblong arcuate locking hole acts as an intermediary mechanism that mediates between the lock and the drum. It transforms the force interaction by providing a gradual engagement path, reducing the peak force required and enabling automated engagement without manual intervention while maintaining adequate locking strength.
3Productivity
If automated locking control is implemented, then productivity is improved, but device complexity increases
Solution Approach 1:
The locking system is designed to be self-aligning and self-locking through the oblong arcuate hole geometry. The shape automatically guides the lock into proper alignment and secures it without requiring complex external control systems, thereby improving productivity while minimizing device complexity.
Solution Approach 2:
The alignment and locking functions are merged into a single geometric feature - the oblong arcuate locking hole. This combination eliminates the need for separate alignment mechanisms and control systems, achieving automated operation with minimal added complexity.
Data Source
Figure 1~2
Figure 3~4
AI summary
Method of securing an angular position of a crane boom that can be moved in raising and lowering by a winch (3) incorporating a motor (30) driving a drum (31) on which a cable is wound and attached to a plate (40) provided with arched oblong locking holes (41), comprising: - measuring a speed parameter (PM) representative of an angular velocity of the boom; - controlling the motor to move the boom with a limitation of the speed parameter to a first maximum value (V1) and a limitation of a motor torque to a first limit value (C1), until reaching an angular position in which a lock (42) is aligned with a locking hole, then locking it in the locking hole;- motor control to move the boom downwards with a limitation of the speed parameter to a second maximum value (V2) and a limitation of the motor torque to a second limit value (C2), until the speed parameter is zero for a predetermined time to stop the motor.