Numerical Controller Look-Ahead Detection for Stable Machining Speed
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Solution Overview
Problem
High-quality machining programs with short minute straight lines and fast command speeds often result in unstable acceleration/deceleration due to insufficient processing time for look-ahead blocks, leading to speed control abnormalities, especially in machines with multiple axes and limited numerical controller processing power.
Innovation Solution
A numerical controller that includes a program execution unit, look-ahead unit, theoretical value calculation unit, measured value calculation unit, abnormal block detection unit, and command speed update unit to detect and address abnormal blocks by calculating and updating command speeds to secure sufficient look-ahead blocks, thereby stabilizing feed rate and cutting speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the command speed is increased and machining programs are made more detailed, then machining quality is improved, but processing time becomes insufficient for look-ahead blocks and speed control abnormalities occur
Solution Approach 1:
The patent implements a feedback mechanism where the numerical controller continuously monitors the number of look-ahead blocks and compares it against a predetermined threshold. When the number of blocks falls below the threshold, the system automatically reduces command speed to ensure sufficient processing time for look-ahead operations, thereby preventing speed control abnormalities while maintaining high machining quality.
Solution Approach 2:
The system dynamically adjusts command speed based on real-time conditions. Instead of using a fixed speed, the numerical controller modifies the command speed adaptively when insufficient look-ahead blocks are detected, allowing the system to optimize between machining quality and processing capability under varying operational conditions.
2Productivity
If the numerical controller processing power is increased to handle high-speed machining, then look-ahead processing capability is improved, but device complexity and cost increase
Solution Approach 1:
Instead of increasing hardware processing power, the patent changes operational parameters by dynamically adjusting command speed based on the number of look-ahead blocks available. This software-based parameter adjustment allows the existing numerical controller to effectively handle high-speed machining without requiring enhanced processing power or increased device complexity.
3Manufacturing precision
If minute straight lines are uniformized with stable acceleration/deceleration, then machining quality is improved, but more blocks are required which increases program complexity
Solution Approach 1:
The feedback mechanism monitors look-ahead block availability and automatically adjusts command speed to ensure sufficient blocks are available for stable acceleration and deceleration control. This prevents speed control abnormalities that would otherwise require manual program optimization, maintaining uniform minute straight lines without unnecessarily increasing program complexity.
Data Source
AI summary
To provide a numerical controller that can detect the position at which the look-ahead blocks used to determine an acceleration/deceleration operation is insufficient in a machining program in order to stabilize feed rate, cutting speed and other factors. A numerical controller includes a program execution unit that executes a machining program, a program look-ahead unit that looks ahead at the machining program in parallel with execution of the machining program, a theoretical value calculation unit that calculates theoretical values per block in processing time for the machining program from the feed rate of the machine tool and lengths of minute straight lines that make up the machining path followed by the machine tool, a measured value calculation unit that calculates actually measured values per block in the look-ahead time taken by the program look-ahead unit and the processing time for the machining program while the machining program is being executed, and an abnormal block detection unit that detects an abnormal block that is a block at which the result of subtracting the total of the theoretical values from the total of the actually measured values is more than a prescribed value.