Numerical Controller Tool Retraction Interference Avoidance
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Solution Overview
Problem
Existing numerical control systems for machine tools face challenges in safely retracting tools during machining interruptions without causing interference with the workpiece, particularly when storage capacity is limited and reversing the machining path is not appropriate, leading to potential damage or incomplete retraction.
Innovation Solution
A numerical controller with a retraction block determination unit that identifies suitable blocks in the machining program for safe tool retraction, allowing the tool to be moved to a preset endpoint and then reversed along the original path to avoid interference, even in complex machining programs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the tool retraction program is constantly calculated and saved involving the opposite direction to the machining program, then the tool can be retracted while avoiding interference, but the storage capacity required increases consistently with the size of the NC machining program
Solution Approach 1:
The patent extracts only the essential retraction information (opposite direction vector and reference position) from the complete machining program, rather than storing the entire program. This selective extraction reduces storage requirements while maintaining the ability to perform safe retraction operations.
Solution Approach 2:
The system pre-calculates and stores only the critical retraction parameters (opposite direction and reference position) before machining begins. This preliminary preparation enables quick retraction responses without requiring storage of the entire machining program, resolving the contradiction between readiness and storage capacity.
2Ease of operation
If the machining program is executed in the opposite direction to perform tool retraction, then the tool can be moved along the machining path, but the rotating position and feed position cannot be accurately determined causing damage to machined portions
Solution Approach 1:
Instead of executing the machining program in reverse, the system calculates the opposite direction vector mathematically and moves the tool along this inverted path. This approach allows retraction movement while avoiding the precision problems of reverse program execution, as the system controls movement based on the original program data rather than attempting to replay it backward.
3Productivity
If the tool is moved a given distance in the direction perpendicular to the tool moving vector and then moved along the retracting path, then the tool retraction program can be executed, but the tool may still interfere with the workpiece at certain points
Solution Approach 1:
The system dynamically determines the retraction path by calculating the opposite direction vector based on the current tool position and orientation in the machining program. Rather than using fixed perpendicular movements, the retraction path adapts to the specific machining context, ensuring the tool moves away from the workpiece along the most appropriate escape route.
Data Source
AI summary
Executable format data resulting from decoding of a positioning block (retraction block) prior to start of cutting and an end point coordinate position P1 for command for the retraction block are stored. When machining is interrupted and a request for retraction of a tool is input, a retracting operation 1 is performed to retract the tool from a machining interruption position P2 to the stored end point coordinate position P1 of the retraction block. Subsequently, the stored executable format data of the retraction block is executed, with a moving direction for the executable format data being reversed to move the tool. The tool performs a retracting operation 2 of moving in the opposite direction along a moving path for in the retraction block. The retracting operations 1, 2 allow the tool to be retracted while avoiding interfering with other members.