Woodworking Machine Safety Architecture for Motorized Stop Positioning
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Solution Overview
Problem
Safety risks arise in material processing machines like saws and milling machines due to motorized adjustment of control objects into danger zones, requiring a high-performance safety architecture that balances safety and cost-effectiveness, especially for achieving minimum performance levels like PLc.
Innovation Solution
A safety architecture that includes two independent sensors for position and speed detection, a main control for actuator positioning, and an auxiliary control for monitoring and validation, ensuring safe operation and reducing component redundancy costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If fully redundant safety architecture is implemented, then safety performance level (PLc) is achieved, but component cost doubles
Solution Approach 1:
The patent applies partial redundancy by implementing safety monitoring only for the critical actuating movement of the control object into the danger area, rather than fully redundant monitoring of all machine functions. The auxiliary control unit monitors specifically the position and speed of the control object during actuating movement, providing sufficient safety for the critical function without duplicating all safety systems.
Solution Approach 2:
The safety architecture is segmented into functional modules: main control unit for normal operation, auxiliary control unit for safety monitoring, first sensor for position detection, and second sensor for speed detection. Each module performs a specific safety function, allowing cost-effective implementation of PLc without requiring complete system redundancy.
2Adaptability or versatility
If motorized adjustment of control object is enabled in danger zone, then machining flexibility is improved, but safety risk increases
Solution Approach 1:
The system continuously monitors the position and speed of the control object during actuating movement using first and second sensors. The auxiliary control unit receives feedback signals from these sensors and compares them against predetermined safety limits. If the control object approaches the danger area or exceeds safe speed, the system automatically interrupts the actuating movement, allowing flexible positioning while maintaining safety through continuous feedback monitoring.
Solution Approach 2:
The auxiliary control unit acts as an intermediary between the main control unit and the actuator. It receives actuating commands from the main control, monitors the actual movement via sensors, and can interrupt the actuator's operation if safety limits are approached. This intermediary layer enables flexible motorized adjustment while preventing dangerous operations.
3Object-affected harmful factors
If safety monitoring of actuating movement is implemented, then collision prevention is achieved, but system complexity increases
Solution Approach 1:
The auxiliary control unit serves multiple safety functions simultaneously: it monitors position, monitors speed, compares sensor signals against safety limits, and can interrupt the actuator. By consolidating these safety functions into a single multi-functional unit rather than separate systems for each function, the patent reduces overall system complexity while achieving comprehensive collision prevention.
Data Source
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AI summary
Woodworking machine with at least one positioning object (230), in particular a workpiece stop, which can be moved by means of an actuator (220) by a controlled positioning movement (221) even in a danger zone (215), wherein the woodworking machine comprises a safety architecture (100) with a first sensor (S1), a second sensor (S2), a main controller (C), an auxiliary controller (AC) and a drive controller (A). The safety architecture enables a high level of safety with lower component requirements.