Boring Tool Calibration for Hole Diameter Deviation Compensation
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Solution Overview
Problem
In metal cutting, especially internal turning or boring, achieving a machined hole with the exact desired diameter is challenging due to tool deflection, leading to time-consuming and labor-intensive processes, and existing methods for compensating for deflection may not provide accurate enough results for tight tolerance applications.
Innovation Solution
A method for calibrating cutting tools that involves measuring radial and tangential cutting forces during machining, using sensors to determine parameters, and applying curve fitting to establish calibration coefficients that account for the effects of tangential cutting forces on radius deviations, allowing for more accurate estimations and compensations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If multiple machining operations with step-wise decreasing cutting depths are used to compensate for tool deflection, then manufacturing precision of hole diameter is improved, but productivity deteriorates due to time-consuming and labor-intensive measurements between operations
Solution Approach 1:
The patent applies preliminary action by performing calibration operations before actual machining to establish a relationship between cutting forces and radius deviations. This pre-established model enables direct compensation during machining without requiring iterative measurements, thus improving productivity while maintaining precision.
Solution Approach 2:
The patent implements feedback by measuring cutting forces during calibration and using this information to determine compensation values for radius deviations. The measured force data feeds into a model that predicts and compensates for deflection, eliminating the need for manual diameter measurements and enabling continuous improvement of machining accuracy.
2Productivity
If strain gauges and accelerometers are used to measure tool deflection and estimate diameter deviation, then productivity is improved by reducing manual measurements, but manufacturing precision deteriorates because the estimation is not accurate enough for tight tolerance applications
Solution Approach 1:
The patent changes the measured parameter from direct deflection measurement to cutting force measurement. By measuring cutting forces with force sensors and establishing a calibrated relationship between forces and radius deviations, the system achieves higher accuracy for tight tolerance applications while maintaining improved productivity through automated compensation.
Solution Approach 2:
The patent substitutes the mechanical deflection measurement system (strain gauges and accelerometers) with a force-based measurement and calculation system. Instead of directly measuring tool deflection, the system measures cutting forces and calculates radius deviations through a calibrated model, providing more accurate results for precision machining.
3Device complexity
If only radial cutting force is considered for compensation, then device complexity is reduced, but manufacturing precision deteriorates because tangential cutting forces also significantly affect radius deviation
Solution Approach 1:
The patent applies universality by creating a comprehensive compensation model that handles both radial and tangential cutting forces through a unified calibration approach. The single calibration process establishes relationships for multiple force components, enabling accurate compensation for complex machining scenarios without requiring separate compensation mechanisms for each force direction.
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 enables precise determination and compensation of radius deviations, reducing the need for multiple machining operations and manual measurements, thereby improving the accuracy and efficiency of hole machining.
Implementation Method 1
determining a value of a first parameter that is dependent on the tangential cutting force and a value of a second parameter that is dependent on the radial cutting force occurring during the machining
Data Source
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AI summary
The invention relates to a method for calibrating a cutting tool arranged to a turning machine for machining the inner surface of a hole in a workpiece of a material. One or more calibration operations are performed in which an inner surface of a calibration hole in the workpiece is machined in accordance with a target radius, whereas values of a first parameter and a second parameter dependent on tangential cutting force and radial cutting force, respectively, are determined. Then, the actual machined radius of the calibration hole is measured, and the difference between the target radius and the actual radius is associated to the first and second parameter values. By applying curve fitting to the resulting data points, a dependence between radius deviation and the first and second parameters is defined and used for identifying a first calibration coefficient indicative of how a tangential cutting force affects a radius of a hole machined in the material by the cutting tool arranged to the turning machine. Such calibration coefficient, together with determined first and second parameter values, may be used to estimate the radius deviation of a subsequently machined hole, making it possible to compensate for such deviation.