Stacking Apparatus Optical Sensor Safety Control
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Solution Overview
Problem
Existing stacking apparatuses for planar articles, such as corrugated material, pose a risk of injury due to the rapid movement of conveyors, which can crush individuals, and previous safety measures like light curtains are inadequate in preventing accidents, especially when operators are between the light curtain and the machinery or during machine resets.
Innovation Solution
A stacking apparatus equipped with optical sensors and a safety controller that detects objects in defined zones, controlling the conveyor's movement to prevent injuries by stopping or slowing it when objects are detected in hazardous areas, and ensuring the conveyor cannot descend without power, using multiple safety sensors and redundancy to enhance safety.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a light curtain is placed close to the machinery to detect objects, then the detection precision is improved, but the machine cannot be stopped in time to avoid user injury
Solution Approach 1:
The patent transitions from a two-dimensional light curtain detection plane to a three-dimensional detection volume using multiple sensors positioned at different locations and angles. This volumetric detection space allows the system to detect objects earlier in their approach path while maintaining adequate stopping distance, resolving the contradiction between detection precision and response time.
Solution Approach 2:
The detection system is divided into multiple independent optical sensors positioned at different locations around the conveyor. Each sensor monitors a specific zone, and the controller integrates signals from all sensors to determine overall safety. This segmentation allows for comprehensive coverage and earlier detection without requiring any single sensor to be positioned too close to the hazard.
2Loss of time
If a light curtain is placed far away from the machinery to allow stopping time, then the response time is improved, but unnecessary shut downs occur due to accidental tripping
Solution Approach 1:
Multiple optical sensor signals are merged and processed by a controller that applies logical evaluation to determine whether to stop the conveyor. The system requires confirmation from multiple sensors or persistent detection to trigger a shutdown, reducing false alarms from accidental tripping while maintaining adequate response time through the distributed sensor arrangement.
Solution Approach 2:
The controller continuously monitors signals from all optical sensors and adjusts conveyor operation based on the integrated feedback. The system evaluates the pattern and persistence of sensor activations to distinguish between genuine hazards requiring shutdown and transient obstructions causing false alarms, thereby improving reliability while maintaining safe response times.
3Object-affected harmful factors
If perimeter protection with light curtains is used to protect operators, then the safety coverage is improved, but operators between the light curtain and machinery remain exposed during resets
Solution Approach 1:
The system performs preliminary safety verification by continuously monitoring multiple sensor zones before allowing conveyor operation to resume after a shutdown. The controller ensures that all detection zones are clear and safe before reactivating the conveyor, preventing operators from being exposed during reset operations. This preliminary check eliminates the vulnerability window that exists in single-point light curtain systems.
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
The solution effectively reduces the risk of human injuries by providing real-time monitoring and control of the conveyor's movement, ensuring safe operation and preventing accidents by stopping the conveyor when objects are detected in danger zones, and maintaining a safe state during power loss.
Implementation Method 1
at least one optical sensor detecting the presence of an object in the main conveyor travel path
Data Source
AI summary
A stacking apparatus includes a base, a main conveyor pivotably supported on the base that is pivotable between a first, lowered, position and a second, raised, position, an accumulator section downstream of a discharge end of the main conveyor for receiving articles from the main conveyor, where the accumulator section includes a support for supporting a stack of items fed to the accumulator section by the main conveyor. Also, at least one optical sensor detecting the presence of an object in the main conveyor travel path and at least one controller operatively connected to the main conveyor and the optical sensor, the at least one controller receiving signals from the optical sensor and controlling the main conveyor based on the signals and on the direction of movement of the main conveyor.