Machine Tool Strain-Sensor Layout for Dynamometer-Free Force Estimation
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Solution Overview
Problem
The high cost of dynamometers makes it desirable to estimate cutting forces in machining processes using alternative methods.
Innovation Solution
A machine tool configuration that includes a first and second surface receiving cutting forces, with strain sensors coupled to these surfaces, allowing for force estimation based on output values, where the surfaces are not parallel and form specific angles relative to the spindle axis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a dynamometer is used to estimate cutting force, then measurement precision is improved, but device cost increases
Solution Approach 1:
The patent replaces the expensive dynamometer with a strain sensor that is cheaper and can be easily replaced. The strain sensor is attached to the tool holder or tool post, providing a cost-effective alternative for cutting force measurement while maintaining adequate measurement precision for machining applications.
Solution Approach 2:
The patent substitutes the complex mechanical dynamometer system with a simpler strain sensor-based measurement system. The strain sensor directly measures deformation in the tool holder or tool post, converting mechanical force into an electrical signal that can be processed to estimate cutting force, thereby eliminating the need for a bulky and expensive dynamometer.
2Ease of manufacture
If a strain sensor is used instead of a dynamometer, then device cost is reduced, but measurement precision may deteriorate
Solution Approach 1:
The patent uses the tool holder or tool post as an intermediary element between the cutting tool and the strain sensor. The strain sensor is attached to this intermediary structure, which transmits the cutting forces to the sensor. This approach allows the use of a cheaper strain sensor while maintaining measurement accuracy by leveraging the mechanical properties of the tool holder or tool post.
Solution Approach 2:
The patent measures cutting force indirectly by detecting strain in the tool holder or tool post rather than directly measuring the force on the tool. This dimensional shift from direct force measurement to strain measurement on a supporting structure enables the use of cheaper sensors while maintaining adequate measurement precision through proper sensor placement and signal processing.
3Measurement precision
If multiple strain sensors are arranged on non-parallel surfaces, then force estimation accuracy is improved, but device complexity increases
Solution Approach 1:
The patent employs asymmetric arrangement of strain sensors on non-parallel surfaces of the tool holder or tool post. By placing sensors on surfaces that are not parallel to each other, the system can capture multi-directional strain components, improving the accuracy of cutting force estimation in three-dimensional space. This asymmetric configuration allows differentiation of force components along different axes.
Solution Approach 2:
The patent divides the force measurement task into multiple independent strain sensor measurements. Each strain sensor measures strain in a specific direction on a specific surface, and the controller integrates these segmented measurements to calculate the total cutting force vector. This segmentation approach improves measurement accuracy by capturing force components from multiple orientations.
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 approach reduces costs by using less expensive strain sensors to accurately estimate cutting forces, enabling effective force monitoring during machining without the need for dynamometers.
Implementation Method 1
a first strain sensor coupled to the first surface and the second surface... obtaining an output value of the first strain sensor
Data Source
AI summary
There is provided a technique to estimate a cutting force by a new method other than use of a dynamometer. A machine tool capable of cutting a workpiece using a tool includes a first surface that receives a force due to the cutting of the workpiece, the first surface being located in the machine tool; and a second surface that receives a force due to the cutting of the workpiece, the second surface being located in the machine tool. The second surface is not parallel to the first surface, and the machine tool includes: a first strain sensor coupled to the first surface and the second surface; and an estimation unit that estimates a force applied to the tool, based on an output value of the first strain sensor during the cutting of the workpiece.