Numerical Controller Neighboring Point Search with Tool Attitude
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Solution Overview
Problem
Existing numerical controllers for machining programs determine neighboring points solely based on distance, leading to unintended block start points being selected when tool attitudes change, especially in three-dimensional machining, causing inaccuracies in restarting the program.
Innovation Solution
A numerical controller with a neighboring point search function that considers both distance and tool attitude, using units to acquire current tool center and attitude positions, analyze machining programs, and determine suitable block start points by comparing attitude differences within preset values, ensuring accurate selection of neighboring points.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If neighboring point search is performed based only on distance between tool center points, then the search is simple and fast, but unintended block start points may be selected when tool attitude changes occur in three-dimensional machining
Solution Approach 1:
The patent extends the neighboring point search from a one-dimensional distance-based criterion to a two-dimensional criterion by incorporating tool attitude (rotation axis angles) as an additional dimension. The attitude determination unit calculates angle differences between the current tool attitude and the attitude at block start points, adding this angular dimension to the existing distance dimension. This resolves the contradiction by improving selection accuracy through multi-dimensional evaluation while maintaining computational efficiency through straightforward angle difference calculations.
2Reliability
If multiple block start points are within neighboring point distance when tool attitude changes, then distance-based selection is ambiguous, but adding attitude consideration increases calculation complexity
Solution Approach 1:
The patent segments the neighboring point selection process into two independent evaluation stages: first evaluating distance criteria, then evaluating attitude criteria. The determination unit separately calculates distance differences and attitude (angle) differences, allowing each criterion to be assessed independently. This segmentation resolves the contradiction by providing a clear, stepwise decision process that improves reliability through comprehensive evaluation while avoiding excessive computational overhead through modular, independent calculations.
3Ease of manufacture
If tool attitude is not considered in neighboring point search, then the search function is simple to implement, but the selected block start point may not match the intended restart point in three-dimensional machining
Solution Approach 1:
The patent introduces an attitude determination unit as an intermediary component that bridges the gap between simple distance-based search and precise machining restart requirements. This intermediary unit calculates tool attitude (rotation axis angles) at block start points and compares them with current attitude, acting as a mediator that translates complex three-dimensional tool orientation data into comparable angle difference values. This resolves the contradiction by maintaining implementation simplicity through a dedicated intermediary module while achieving high precision through comprehensive attitude evaluation.
Data Source
AI summary
A numerical controller includes a neighboring point search function that moves a tool controlled by a moving axis and a rotation axis onto a machining path directed by a machining program within the range of a neighboring point distance from a current position of the tool. When searching the neighboring point, the numerical controller determines a neighboring point with consideration for both a tool center point position and a tool attitude. By employing this search method, even when a plurality of block start points are present in the neighboring point distance from the current tool position, a block start point of the block originally desired to be restarted can be determined as a neighboring point.