Real-time Tool Path Adaptation Using Force Feedback
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Solution Overview
Problem
Current milling machine control systems face challenges in maintaining machining process constraints, particularly when dealing with inconsistent raw material dimensions and conditions, leading to inefficient cutting tool life and increased runtime due to factors like tool breakage and rubbing effects.
Innovation Solution
A system that modifies the cutting tool path in real-time using force feedback loops to adjust radial cutting depth and maintain machining process constraints, allowing for adaptive control of cutting forces and tool path adjustments during the machining process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a fixed tool path is used based on nominal dimensions, then the machining process is simple to control, but the cutting tool may experience excessive forces leading to breakage or rubbing effects when material dimensions vary
Solution Approach 1:
The system incorporates force feedback sensors that continuously monitor cutting forces during machining. When the material depth is greater than expected, the increased cutting force is detected and fed back to the control system, which then automatically adjusts the tool path to reduce radial cutting depth and maintain forces within acceptable limits, preventing tool breakage and rubbing effects
Solution Approach 2:
The tool path is transformed from a static, pre-programmed trajectory to a dynamic path that adapts in real-time based on actual cutting conditions. The control system continuously modifies the tool's radial cutting depth and positioning based on force feedback, enabling the system to respond to material variations without requiring complex manual intervention
2Reliability
If safety offsets are applied to account for material variation, then tool breakage is prevented, but machining runtime increases due to reduced feed rates
Solution Approach 1:
Instead of applying conservative safety offsets that reduce feed rates, the system uses real-time force feedback to dynamically adjust the tool path. This allows the system to maintain higher feed rates when cutting conditions are favorable while only reducing speed when actual forces indicate a risk of tool damage, thereby improving productivity without sacrificing reliability
Solution Approach 2:
The system dynamically changes machining parameters including radial cutting depth, feed rate, and tool positioning based on real-time force measurements. This allows optimization of the machining process by adjusting parameters to match actual material conditions rather than relying on fixed conservative parameters
3Productivity
If radial cutting depth is increased to improve material removal rate, then productivity increases, but cutting forces exceed constraints causing tool damage
Solution Approach 1:
The force feedback system continuously monitors cutting forces and provides real-time information to the control system. When forces approach constraint limits, the system automatically reduces radial cutting depth to maintain forces within acceptable ranges, preventing tool damage while maximizing material removal rate under actual operating conditions
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 ensures consistent machining forces, optimal cutting tool life, and reduced machining costs by eliminating the need for safety offsets and minimizing runtime, especially when working with hard materials like titanium and stainless steel.
Implementation Method 1
A value of a machining process force parameter is determined from sensor data received during cutting along the defined initial tool path. The determined value of the machining process force parameter and the machining process force constraint are compared, and the cutting tool is caused to cut along a modified tool path such that radial cutting depth changes and values of the machining process force parameter do not exceed the machining process force constraint.
Data Source
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AI summary
A method for machining a workpiece (2) using a cutting tool (4) attached to a spindle (30). The method comprises: (a) defining an initial tool path of the cutting tool (4) relative to a workpiece (2) using part definition data; (b) causing the cutting tool (4) to cut along the defined initial tool path relative to the workpiece (2); (c) receiving sensor (18) data representing machining process conditions (e.g. cutting force) during said cutting along the defined initial tool path; (d) processing the sensor (18) data to determine a value of a machining process force parameter; and (e) causing the cutting tool (4) to cut along a modified tool path relative to the workpiece (2) such that the radial cutting depth changes and values of the machining process force parameter does not exceed a machining process force constraint. Operations (b) through (e) are performed by a computer system (50).