CNC Look-Ahead Buffer Allocation for Stable High-Speed Machining
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Solution Overview
Problem
High-quality machining programs with short minute straight lines and fast command speeds lead to instability in acceleration/deceleration due to insufficient look-ahead blocks, causing speed control abnormalities, especially in multi-axis machining systems with limited processing power.
Innovation Solution
A numerical controller with a control unit and storage unit that includes a program execution unit, a program look-ahead unit, and a look-ahead allocation unit, which divides memory into regions to perform parallel look-ahead processing from the start of the machining program, detecting exhaustion blocks and machining precision requirement blocks to stabilize feed rate and cutting speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the command speed is increased to achieve high-speed machining, then productivity is improved, but the processing time for executing the program becomes too short to secure sufficient look-ahead blocks, causing speed control abnormalities
Solution Approach 1:
The numerical controller performs look-ahead processing in advance by analyzing the machining program before execution and storing analysis results (acceleration/deceleration operations, feed rate commands) in a buffer. This preliminary action ensures that when high-speed machining occurs, the control data is already prepared, allowing sufficient look-ahead blocks to be secured even with short processing times.
Solution Approach 2:
The machining program is divided into multiple blocks that are processed sequentially through the buffer. The buffer stores a plurality of blocks in advance, allowing the controller to segment the processing into manageable units. This segmentation enables the system to maintain sufficient look-ahead blocks by continuously replenishing the buffer with pre-analyzed program segments.
2Manufacturing precision
If the processing power of the numerical controller is increased to handle look-ahead processing, then manufacturing precision is improved, but the device complexity and cost increase
Solution Approach 1:
The controller performs analysis processing of the machining program in advance and stores the results in the buffer. By preprocessing the program data and storing acceleration/deceleration operations and feed rate commands before execution, the system reduces the real-time processing burden during high-speed machining while maintaining high manufacturing precision.
Solution Approach 2:
The buffer acts as an intermediary between the machining program input and the execution output. It stores pre-analyzed data including acceleration/deceleration operations and feed rate commands, mediating the data flow to ensure sufficient look-ahead blocks are available without requiring continuously high processing power during execution.
3Reliability
If the buffer data amount is monitored to detect insufficient data, then reliability is improved, but the complexity of detection and measurement increases
Solution Approach 1:
The numerical controller monitors the buffer data amount and compares it against a predetermined threshold value. When the buffer data amount falls below this threshold, the controller generates a warning signal or stops program execution. This feedback mechanism provides simple, reliable detection of insufficient data without complex measurement systems.
Solution Approach 2:
The system changes the monitoring parameter from complex real-time analysis to a simple data amount threshold comparison. By monitoring whether the buffer data amount exceeds a predetermined threshold value, the system achieves reliable detection with minimal computational complexity.
Data Source
AI summary
To provide a numerical controller that can detect a position in a machining program at which a speed control abnormality is likely to occur due to an insufficient look-ahead blocks that are used to determine an acceleration/deceleration operation, and start a look-ahead processing function from the position in parallel with looking ahead at the machining program from the start of the machining program. A numerical controller includes a program execution unit that executes a machining program, a program look-ahead unit that simultaneously looks ahead at the machining program from different blocks in the machining program in parallel with execution of the machining program and that includes a first program look-ahead unit and a second program look-ahead unit, and a look-ahead allocation unit that divides a storage unit into at least a first region and a second region and instructs the first program look-ahead unit to perform a look-ahead action of storing look-ahead blocks in the first region and instructs the second program look-ahead unit to perform a look-ahead action of storing look-ahead blocks in the second region.