Machine Tool Spindle Concentricity Correction for Dual-Sided Hole Machining
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Solution Overview
Problem
Existing machine tools face issues with concentricity errors when machining holes on both sides of a workpiece due to parallelism errors in the main spindle, leading to inaccurate assembly, noise, vibration, and uneven wear during operations.
Innovation Solution
An apparatus and method that corrects the concentricity of a main spindle by calculating and applying a concentricity correction amount based on reference tool information, including parallelism and length differences, to align holes machined on both sides of a workpiece despite tool length variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the main spindle is manufactured with standard tolerances, then manufacturing cost and ease of assembly are improved, but concentricity precision of holes machined on both sides of the workpiece deteriorates
Solution Approach 1:
The patent measures the parallelism error of the main spindle beforehand and calculates a correction amount that is stored and applied during subsequent machining operations. This preliminary measurement and correction setup enables standard tolerances to be used during manufacturing while achieving high concentricity precision during operation.
Solution Approach 2:
The patent changes the parameter of spindle position by applying a calculated correction amount in the X-axis direction based on the measured parallelism error. This parameter adjustment compensates for manufacturing tolerances and achieves the required concentricity precision without requiring ultra-precise manufacturing.
2Manufacturing precision
If the main spindle is manufactured with high precision to eliminate parallelism error, then concentricity precision is improved, but manufacturing cost and complexity increase
Solution Approach 1:
The machine tool performs self-diagnosis and self-correction by measuring its own parallelism error, calculating the correction amount, and applying it automatically during machining operations. This self-service approach eliminates the need for complex mechanical correction mechanisms or ultra-precise manufacturing.
Solution Approach 2:
The patent replaces complex mechanical correction mechanisms with a computational approach that uses measurement data and numerical calculation to determine and apply the correction amount, simplifying the overall system while achieving high precision.
3Productivity
If the table is rotated 180 degrees to machine holes on both sides of the workpiece, then productivity is improved, but concentricity error increases due to parallelism error of the tool
Solution Approach 1:
The patent introduces feedback by measuring the parallelism error of the main spindle and using this information to calculate and apply a correction amount during machining operations. This feedback loop ensures that concentricity is maintained when the table is rotated 180 degrees to machine both sides of the workpiece.
Solution Approach 2:
The parallelism error is measured and the correction amount is calculated in advance before machining operations begin. This preliminary action ensures that the correction is already in place when performing dual-sided machining, maintaining concentricity while improving productivity.
4Length of moving object
If tool length is increased to machine deeper holes, then machining capability is improved, but concentricity error increases due to amplification of parallelism error
Solution Approach 1:
The patent adjusts the spindle position parameter in the X-axis direction based on the measured parallelism error and calculates a correction amount that compensates for the amplification effect of long tool length. This parameter change maintains concentricity precision regardless of tool length or hole depth.
Data Source
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AI summary
A method of correcting concentricity of a main spindle of a machine tool includes recording a reference tool length and a parallelism error, setting a half of the parallelism error as a concentricity correction constant of the reference tool, calculating an additional concentricity correction amount of the main spindle for an expected tool by adding or subtracting a parallelism error of the reference tool in proportion to a length difference between the reference tool and the expected tool, calculating a concentricity error correction amount of the main spindle for the expected tool by adding the concentricity correction constant of the reference tool, and correcting a parallelism error of the main spindle by executing a command of moving the main spindle by the concentricity correction amount in the X axis direction.