NC Look-Ahead Feed Control for Speed Reduction Blocks
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Solution Overview
Problem
High-quality machining programs with short minute straight lines and fast command speeds face issues due to insufficient processing time for look-ahead blocks, leading to unstable acceleration/deceleration and speed changes, particularly in machines with multiple axes and limited numerical controller processing power.
Innovation Solution
A numerical controller with a program execution unit, look-ahead unit, speed reduction block detection, and speed information storage and read units, which detects and manages speed reduction blocks by calculating and storing feed rates, and applying them to axes to stabilize feed rate and cutting speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the command speed is increased to improve productivity, then the machining efficiency is improved, but the processing time for look-ahead blocks becomes insufficient leading to unstable acceleration/deceleration
Solution Approach 1:
The numerical controller performs look-ahead processing in advance to analyze upcoming NC blocks and determine acceleration/deceleration operations before execution. By pre-calculating speed profiles and storing them in a buffer, the system ensures that speed control decisions are made with sufficient time, even when command speeds are high and processing time is limited.
2Measurement precision
If the number of look-ahead blocks is increased to improve speed control accuracy, then the acceleration/deceleration determination accuracy is improved, but the buffer memory requirement and processing complexity increase
Solution Approach 1:
The system monitors the buffer state continuously and compares the number of available look-ahead blocks against a predetermined threshold. When the threshold is met, the controller executes the determined speed profile; when not met, it adjusts processing priority or reduces look-ahead depth dynamically. This feedback mechanism optimizes the balance between accuracy and complexity without requiring excessive buffer resources.
3Power
If the processing power of the numerical controller is increased to handle high-speed machining, then the look-ahead processing capability is improved, but the device cost and complexity increase
Solution Approach 1:
The look-ahead processing is divided into discrete blocks (NC blocks) that are analyzed sequentially. The buffer stores a limited number of pre-analyzed blocks, and the system processes them in stages rather than analyzing the entire program at once. This segmentation allows the controller to maintain adequate processing power while managing complexity through modular, incremental analysis of the machining program.
Data Source
AI summary
To provide a numerical controller that can produce high-quality machining with optimal machining conditions by reducing speed control abnormalities in order to stabilize feed rate, cutting speed and other factors. A numerical controller includes a speed reduction block detection unit that detects a speed reduction block that is a block at which the number of blocks to be looked ahead in a machining program relatively decreases, a speed information storage unit that calculates feed rate at each axis from a table feed rate at the speed reduction block and stores this speed information in a storage unit, and a speed information read unit that reads out the speed information from the storage unit and applies the speed information as the feed rate at each axis.