Dynamic Cutter Radius Compensation for CNC Tool Deflection
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Solution Overview
Problem
Existing methods for considering machining forces in machining processes are computationally complex and difficult to apply to more complex machining operations.
Innovation Solution
A method where the numerical control dynamically varies the geometric dimension of the machining tool in real time based on the machining force, without physically altering the tool, by simulating a change in geometry to compensate for deflection caused by machining forces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the relationship between torque and displacement is determined individually for each axis using axis stiffnesses, then the machining force can be taken into account, but the computational complexity increases significantly
Solution Approach 1:
The patent segments the complex multi-axis stiffness problem into a single effective cutter radius parameter. Instead of determining separate axis stiffnesses for each position-controlled axis, the method uses one unified radius compensation value that accounts for the combined effect of all axes, dramatically reducing computational complexity while maintaining machining precision
Solution Approach 2:
The patent changes the parameter representation from multiple axis stiffness values to a single dynamic cutter radius parameter. This parameter transformation simplifies the mathematical model from complex multi-dimensional stiffness calculations to a single-parameter radius adjustment, making the system computationally efficient while preserving the ability to compensate for machining forces
2Manufacturing precision
If the geometric dimension of the machining tool is dynamically varied based on machining force, then the deflection can be compensated, but the control system complexity increases
Solution Approach 1:
The patent creates a virtual copy of the tool geometry parameter (cutter radius) that can be dynamically adjusted without physically changing the tool. This virtual radius parameter mirrors the actual tool geometry but allows for computational modification to compensate for deflection, simplifying the control system compared to physical tool adjustment mechanisms
Solution Approach 2:
The dynamically adjusted cutter radius parameter serves multiple functions simultaneously: it represents the actual tool geometry, compensates for machining force-induced deflection, and automatically adjusts target positions for all position-controlled axes. This single parameter performs what would otherwise require multiple separate control adjustments
Data Source
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AI summary
A numerical controller (4) of a machine tool receives a parts program (7) which determines a path (8) along which a workpiece (2) should be machined in a material-removing manner by means of a machining tool (3) of the machine tool. For a number of position-controlled axes (1) of the machine tool, with which the machining tool (3) is moved in a position-controlled manner relative to the workpiece (1), the numerical controller determines control commands (Ci) by utilising the parts program (7) and controls the position-controlled axes (1) according to the determined control commands (Ci). The numerical controller (4) determines the control commands (Ci) in such a way that the workpiece (2) is machined in a material-removing manner by the machining tool (3) along the path (8) determined by the parts program (7). During the machining of the workpiece (2) by the machining tool (3), the numerical controller receives, in real time, actual values (I) that are characteristic of a machining force (F) exerted on the machining tool (3) during the machining of the workpiece (2) by the machining tool (3). The numerical controller (4) takes a geometrical measurement (g) of the machining tool (3) and the machining force (F) into consideration in the determining of the control commands (Ci). The consideration of the machining force (F) is achieved in that, during the machining process, the geometrical measurement (g) of the machining tool (3) is varied dynamically and in real time according to to the machining force (F).