Numerical Control Device for Machine Tool Feed Axis
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Solution Overview
Problem
Existing numerical control methods for machine tools do not account for variations in rigidity and friction coefficients along the feed axis position, leading to unstable machining precision due to 'stick motion' issues.
Innovation Solution
Divide the feed axis movement range into regions and store corresponding control parameters, analyzing the machining path to read and apply the appropriate parameters for stable control, including acceleration/deceleration time constants, feedback gains, and stick motion correction parameters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single set of control parameters is used for the entire feed axis movement range, then the device complexity is reduced, but the manufacturing precision deteriorates due to stick motion caused by varying rigidity and friction coefficients at different positions
Solution Approach 1:
The feed axis movement range is divided into multiple regions along the feed axis, with each region having its own optimized control parameters. This segmentation allows the system to account for positional variations in rigidity and friction coefficients, thereby maintaining high machining precision throughout the entire movement range while managing complexity through organized parameter storage
Solution Approach 2:
Different control parameters are applied to different regions of the feed axis movement range based on the local mechanical characteristics (rigidity and friction coefficients) at each position. This local optimization ensures that the control parameters are tailored to the specific conditions at each feed axis position, eliminating stick motion and maintaining consistent machining precision
2Manufacturing precision
If control parameters are changed dynamically during machining, then the manufacturing precision is improved, but the device complexity increases due to real-time parameter analysis and switching mechanisms
Solution Approach 1:
The feed axis movement range is pre-divided into multiple regions, and control parameters for each region are determined and stored in advance. During machining, the system simply retrieves the appropriate pre-calculated parameters based on the current region, avoiding the need for complex real-time calculations while still achieving high precision through parameter optimization
Data Source
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AI summary
A numerical control device which controls a feed axis of a machine tool (10) has a storage unit (92) which divides a range of movement of the feed axis into a plurality of regions and stores a plurality of control parameters corresponding to said divided plurality of regions in advance, a position detection unit which detects a position of a feed axis at the time of machining a workpiece, a parameter selection unit (90) which reads out control parameters corresponding to a divided region to which the detected feed axis position at the time of machining a workpiece belongs, and a servo control unit (52) which controls the feed axis using said read control parameters. Due to this, it is possible to provide a numerical control method of a machine tool which realizes stable machining precision without regard as to the feed axis position and a numerical control device which conducts that method.