Numerical Controller Tool Retraction Path Generation
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Solution Overview
Problem
Existing numerical controllers face challenges in safely retracting tools from workpieces during machining interruptions without damaging the machined surface, particularly when the machining program lacks information on tool offset or positional relationships, and existing techniques are inadequate for handling down-cut or up-cut methods.
Innovation Solution
A numerical controller that identifies the machining method as down-cut or up-cut and determines the tool retraction direction based on the spindle rotation direction and feed direction to generate a suitable retraction path, ensuring the tool is retracted axially after radial retraction, thereby preventing surface flaws.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the tool is retracted in the Z-axis direction using conventional techniques, then the tool can be separated from the workpiece, but the machined surface may be flawed longitudinally
Solution Approach 1:
The patent applies dynamics by making the retraction path adaptive rather than fixed. The controller dynamically determines the retraction direction based on real-time identification of the machining method (up-cut or down-cut) and the current tool position, allowing the system to adjust the retraction trajectory to match the specific machining conditions and prevent surface flaws
Solution Approach 2:
The patent changes the parameter of retraction direction from a fixed Z-axis direction to a variable direction determined by machining method identification. By identifying whether up-cut or down-cut machining is being performed and calculating the appropriate retraction direction based on spindle rotation and feed direction, the system optimizes the retraction path to avoid damaging the machined surface
2Ease of operation
If the tool is retracted using tool offset function, then the tool can be retracted in offset vector direction, but it cannot handle cases where G-code command for tool offset is not described
Solution Approach 1:
The patent applies self-service by enabling the system to automatically determine the retraction direction without requiring external tool offset information from the machining program. The controller identifies the machining method and calculates the retraction direction based on spindle rotation direction and feed direction, making the system self-sufficient and compatible with programs that do not include tool offset commands
Solution Approach 2:
The patent achieves universality by creating a retraction control method that works with both programs that include tool offset commands and those that do not. By identifying the machining method (up-cut or down-cut) and determining retraction direction based on fundamental machining parameters rather than program-specific offset information, the system becomes universally applicable across different programming approaches
3Ease of manufacture
If the machining program does not include tool offset information, then the program can be created based on tool radius offset consideration, but it is difficult to determine tool retraction direction based on positional relationship
Solution Approach 1:
The patent applies feedback by using the identified machining method (up-cut or down-cut) and current spindle rotation direction and feed direction to determine the appropriate retraction direction. This feedback mechanism allows the system to automatically calculate the correct retraction path without needing pre-programmed tool offset information, resolving the difficulty of determining positional relationships
Data Source
AI summary
A numerical controller has a tool retraction function for retracting a tool so as not to damage the machined surface of a workpiece when machining of the workpiece by a machine tool is interrupted. The numerical controller identifies a machining method for the machining to be interrupted when a command to interrupt the machining is detected, determines the direction of the retraction of the tool, based on the identified machining method and the feed direction and the rotation direction of a spindle in the machining to be interrupted, and generates a movement path of the tool in the determined retraction direction.