Oscillating Machine Tool Kickback Detection by Position-Based Sampling
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Solution Overview
Problem
Existing methods for identifying deflections or breakdowns in machine tools with oscillating output movements, such as saber saws, face challenges in accurately and quickly detecting changes in rotation speed due to strong fluctuations, leading to potential user safety risks and increased service life issues.
Innovation Solution
A method that continuously or periodically detects physical characteristics of machine tools using a detection unit, analyzing at least two values of these characteristics at different times to identify deflections or breakdowns based on substantially identical position characteristics, allowing for fast identification and differentiation between deflections and breakdowns without requiring extensive filtering of rotation speed data.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If rotation speed data is continuously monitored to identify deflections or breakdowns, then detection reliability improves, but measurement precision deteriorates due to strong fluctuations in the oscillating movement
Solution Approach 1:
The patent applies preliminary action by pre-defining specific position characteristics (such as specific points in the oscillating cycle) at which rotation speed values are evaluated. Instead of continuously analyzing all rotation speed data, the system prepares evaluation criteria in advance and only compares values at these predetermined positions, enabling reliable deflection detection while filtering out irrelevant fluctuations caused by the oscillating movement pattern
Solution Approach 2:
The patent changes the parameter evaluation approach by shifting from continuous rotation speed monitoring to discrete position-based sampling. The system evaluates rotation speed values only at specific positions within the oscillating cycle, effectively transforming the measurement strategy to match the periodic nature of the machine tool's movement, thereby maintaining precision while ensuring reliable defect detection
2Measurement precision
If extensive filtering of rotation speed data is applied to identify deflections, then measurement precision improves, but detection speed decreases leading to delayed safety responses
Solution Approach 1:
The system performs preliminary action by pre-establishing the evaluation framework with predetermined position characteristics before operation begins. During runtime, no extensive filtering or complex signal processing is needed - the system simply compares rotation speed values at these pre-defined positions against threshold criteria, achieving both high detection accuracy and rapid response times for safety-critical deflection identification
Solution Approach 2:
The patent applies partial action by selectively evaluating rotation speed data only at specific critical positions within the oscillating cycle rather than processing the entire continuous data stream. This partial sampling approach provides sufficient information for accurate deflection detection while dramatically reducing computational load and enabling faster detection responses
3Reliability
If continuous monitoring of physical characteristics is implemented, then detection reliability improves, but energy consumption increases
Solution Approach 1:
The patent implements periodic action by monitoring rotation speed values at discrete, periodic intervals corresponding to specific positions in the oscillating cycle rather than continuous monitoring. The detection unit evaluates parameters only at these predetermined moments, maintaining reliable defect detection capability while significantly reducing energy consumption compared to continuous data acquisition and processing
Solution Approach 2:
The system applies partial monitoring by selectively measuring and evaluating rotation speed parameters only at specific critical positions during the oscillating cycle. This partial observation strategy provides adequate information for reliable deflection and breakdown detection while minimizing the operational time and energy expenditure of the detection unit
Data Source
AI summary
In a method for identifying a deflection or a breakdown of a machine tool, in particular a hand-held machine tool, with an oscillating output movement, in particular a linearly oscillating output movement, at least one physical characteristic of the machine tool, in particular of a motor, a powertrain component, and/or a machining tool of the machine tool, is detected continuously or periodically by means of a detection unit. The method further includes detecting a deflection or a breakdown of the machine tool with an analysis unit on the basis of at least two values, which are identified at different times, of the characteristic of the machine tool, wherein each of the at least two values of the characteristic are associated with at least one respective substantially identical value of a discrete position characteristic of the oscillating output movement, in particular the linearly oscillating output movement, of the machine tool.