Hoist Motor Control for Secondary Tipping Moment Limiting
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Solution Overview
Problem
Industrial machines like electric rope shovels experience increased stress and fatigue due to dynamic tipping loads during digging and dumping operations, leading to potential weld cracking and reduced operational life, as conventional systems do not effectively limit secondary tipping moments.
Innovation Solution
A control system that utilizes a controller to monitor the shovel's swing speed and state, adjusting the hoist motor's speed and acceleration/deceleration rates to mitigate secondary tipping loads by limiting peak hoist torques during the unloading process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional power shovels operate with constant speed and acceleration parameters, then productivity and ease of operation are maintained, but secondary tipping loads increase causing structural fatigue and reduced machine life
Solution Approach 1:
The control system dynamically adjusts hoist motor speed and acceleration parameters based on real-time detection of dipper position and load conditions. During the dumping cycle, the system automatically modifies operational parameters to limit secondary tipping moments, transitioning from constant parameters to adaptive parameters that respond to changing operational states.
Solution Approach 2:
The invention changes the operational parameters of the hoist motor during specific phases of the dumping cycle. By detecting when the dipper is in the dumping position and when secondary tipping loads occur, the system adjusts speed and acceleration parameters to reduce peak loads, thereby protecting structural components while maintaining overall productivity.
2Productivity
If the hoist motor operates at high speed with high acceleration rates, then productivity is improved, but secondary tipping moments increase causing stress and weld cracking in machine structures
Solution Approach 1:
The control system applies preliminary anti-action by detecting the dumping cycle phase in advance and pre-adjusting the hoist motor parameters before peak secondary tipping loads occur. This prevents excessive stress on structural components while maintaining high productivity during non-critical phases of operation.
3Ease of operation
If constant operating parameters are used during all phases, then ease of operation is maintained, but unnecessary secondary forces occur during dumping causing fatigue loading
Solution Approach 1:
The control system provides self-service by automatically detecting operational phases and adjusting parameters without requiring operator intervention. The system monitors dipper position, swing speed, and load conditions to autonomously apply secondary tipping moment limits during dumping cycles, maintaining ease of operation while protecting structural integrity.
Data Source
AI summary
A method of controlling a digging operation of an industrial machine. The industrial machine includes a dipper connected to a dipper handle, a hoist rope attached to the dipper, and a hoist motor moving the hoist rope and the dipper. The method includes determining that the dipper is ready to be unloaded, activating a secondary tipping control operation by controlling a speed of the hoist motor, controlling an acceleration ramp rate of the hoist motor, and controlling a deceleration ramp rate of the hoist motor. The method further includes determining when the dipper is unloaded and deactivating the secondary tipping control operation.