Adaptive Kickback Protection for Electric Machine Tools
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Solution Overview
Problem
Electric machine tools face hazardous torque peaks during kickback events, leading to unpredictable and potentially harmful situations for users, as existing protective functions activate uniformly across all operating conditions without accurately recognizing the specific situation.
Innovation Solution
The method adapts evaluation methods to different operating modes of electric machine tools, using various sensors and evaluation devices to detect parameters like rotational acceleration and deflection, allowing for tailored responses to critical situations, such as reducing motor power or switching it off, thereby enhancing user safety and operational reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If kickback protective function is activated at low rotational speed, then user safety is improved, but unnecessary shutdowns occur reducing productivity
Solution Approach 1:
The protective function's sensitivity and activation thresholds are dynamically adjusted based on the operating mode and operational context. In drilling mode at low rotational speeds, the system maintains safety monitoring while avoiding unnecessary shutdowns by considering the specific characteristics of that mode, thus preserving both user safety and productivity.
Solution Approach 2:
Different evaluation criteria and sensitivity levels are applied to different operating modes and speed ranges. Rather than using a single uniform threshold, the system tailors the protective function's parameters to the local conditions of each operating mode, enabling accurate kickback detection when necessary while avoiding false positives that would reduce productivity.
2Measurement precision
If evaluation criteria are adapted to different operating modes, then accurate kickback recognition is improved, but device complexity increases
Solution Approach 1:
The control device is designed with multi-functionality, serving both as the primary controller for motor operation and as the kickback detection evaluator. By integrating the evaluation function into the existing control device rather than adding separate dedicated hardware, the system achieves mode-adaptive kickback recognition while minimizing the increase in overall device complexity.
Solution Approach 2:
The patent combines multiple functions (motor control, operating mode detection, kickback evaluation, and protective activation) into a single integrated control device. This merging of functions allows the system to adapt evaluation criteria to different operating modes without requiring separate complex subsystems, thus achieving high recognition accuracy while controlling device complexity.
Data Source
AI summary
In a method for controlling an electric machine tool having an electric motor for driving a rotating insertion tool, the electric machine tool is operated in one of multiple operating modes, and at least one parameter of the machine tool is detected. The instantaneous operating state of the electric machine tool is ascertained and evaluated based on the detected parameter. A protective function is activated when the presence of a critical operating situation is recognized during the evaluation of the instantaneous operating state. The instantaneous operating mode of the electric machine tool is detected, and the evaluation of the instantaneous operating state is adapted in each case to the instantaneous operating mode.