Numerical Controller Stop-Retraction Path for Five-Axis Machining
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Solution Overview
Problem
Conventional numerical controllers for machine tools leave a trace on the machined surface when machining is interrupted due to the tool being stopped with the workpiece, which reduces surface quality.
Innovation Solution
A numerical controller that decelerates and retracts the tool along a stop-retraction path, combining deceleration and retraction operations simultaneously, ensuring the tool moves away from the workpiece in the tool direction, even during five-axis machining, using a command reading unit, stop signal sensing unit, deceleration stop unit, stop-retraction path generation unit, and interpolation unit to manage axis positions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the tool is decelerated and stopped along the machining path before retraction, then the workpiece is prevented from being deformed due to interruption, but a trace is left on the machined surface reducing surface quality
Solution Approach 1:
The patent applies preliminary action by generating a stop retraction path that pre-calculates and combines the deceleration stop and retraction movements into a single coordinated trajectory. This allows the tool to simultaneously decelerate along the machining path and retract in the tool direction, preventing both workpiece deformation and surface trace formation by executing both protective actions in advance rather than sequentially
Solution Approach 2:
The patent merges the deceleration stop operation and retraction operation into a single combined stop retraction path. Instead of performing deceleration stop first and then retraction separately, the control unit integrates both movements into one coordinated action where the tool decelerates and retracts simultaneously along the combined path, eliminating the trace-causing intermediate state
2Speed
If the tool is retracted in a direction other than the tool direction, then retraction speed may be increased, but the tool and workpiece may interfere with each other causing damage
Solution Approach 1:
The patent applies dynamics by making the retraction direction adaptive rather than fixed. The stop retraction path is generated based on the current tool direction, which may change during five-axis machining. This dynamic adjustment ensures the tool always retracts along its current orientation, preventing interference with the workpiece while maintaining optimal retraction speed for each specific machining position
3Length of moving object
If the tool is retracted after temporary deceleration stop, then the retraction distance is sufficient, but the time required for retraction is increased
Solution Approach 1:
The patent applies continuity of useful action by eliminating the idle intermediate stop phase between deceleration and retraction. The combined stop retraction path ensures the tool continuously moves along a trajectory that simultaneously achieves deceleration and retraction, maintaining productive motion throughout the entire interruption response rather than pausing midway, thus reducing total retraction time while ensuring sufficient separation distance
Data Source
AI summary
A numerical controller which controls a five-axis machining machine having two rotary axes generates speed data for deceleration stop along movement paths when a stop signal that requires interruption of machining and retraction is sensed, and based on the speed data, generates stop retraction path command data combining a path for the deceleration stop along the movement paths and a retraction path receding from the movement paths.