Power Tool Strain Gauge Layout for Kickback And Wear Detection
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Solution Overview
Problem
Existing power tools lack effective detection of kickback events and tool wear conditions due to limitations in strain gauge placement and sensitivity, which can lead to operational safety issues and reduced efficiency.
Innovation Solution
A strain gauge arrangement is placed on a stationary structural section coupled to the pivot bearing in a force-transmitting manner, allowing for detection of mechanical vector quantities in multiple spatial directions, enabling early recognition of kickback events and tool wear conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the strain gauge arrangement is placed directly on the pivot bearing to detect forces, then the detection sensitivity is improved, but the manufacturing complexity and difficulty increase significantly
Solution Approach 1:
The patent introduces a stationary structural section as an intermediary component between the pivot bearing and the strain gauge arrangement. This structural section is coupled to the pivot bearing in a force-transmitting manner, allowing forces to be transmitted from the pivot bearing through the structural section to the strain gauges. This intermediary structure enables the strain gauges to be positioned away from the pivot bearing while still detecting the forces, thereby reducing manufacturing complexity while maintaining detection sensitivity.
2Measurement precision
If the strain gauge arrangement is placed on the pivot bearing to detect kickback events, then the detection accuracy is improved, but the ease of manufacture deteriorates
Solution Approach 1:
The patent segments the force detection system into two separate functional components: the pivot bearing that experiences the forces during operation, and the stationary structural section that houses the strain gauge arrangement. This segmentation allows the strain gauges to be mounted on a separate, more accessible structure rather than directly on the pivot bearing, significantly improving ease of manufacture while maintaining detection accuracy through the force-transmitting coupling.
3Adaptability or versatility
If the strain gauge arrangement is distributed along a path encircling the shaft to measure forces in multiple directions, then the measurement capability is improved, but the device complexity increases
Solution Approach 1:
The stationary structural section serves multiple functions: it supports the pivot bearing, transmits forces from the pivot bearing, and provides a mounting platform for the distributed strain gauge arrangement. This multi-functional design allows the system to achieve enhanced measurement capability in multiple spatial directions while avoiding the complexity that would arise from adding separate components for each function.
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
This solution enhances the detection of kickback events and tool wear conditions, improving operational safety and efficiency by providing timely alerts and preventive measures.
Implementation Method 1
a strain gauge arrangement (2) for detecting a mechanical variable (3) that depends on a force emanating from the tool (1)
Data Source
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AI summary
The invention relates to an electric tool (10, 20, 30, 40, 50) comprising: a support structure (21); a pivot bearing (27) mounted on the support structure (21); a shaft (8) mounted on the support structure (21) via the pivot bearing (27); a tool (1) which is rotatably coupled to the shaft (8), in particular a saw blade, a milling cutter, or an abrasive wheel; a strain gauge assembly (2) for detecting a mechanical variable (3) which depends on a force originating from the tool (1); and a control device (4) which is designed to detect an occurrence and/or a state of the electric tool (10, 20, 30, 40, 50) according to the detected mechanical variable. The strain gauge assembly (2) is mounted on a stationary structure portion (5) coupled in a force-transmitting manner to the pivot bearing (27), and is not mounted on the pivot bearing (27).