Numerical Controller Speed Smoothing for Machining Surface Quality
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Solution Overview
Problem
Conventional machining technologies experience issues with steep changes in machining load due to abrupt speed changes during acceleration and deceleration, leading to reduced tool life and inconsistent machining surface quality.
Innovation Solution
A numerical controller that analyzes machining programs, generates control points based on cumulative moving distances and designated speeds, and outputs commanded speeds using parametric curves such as B-spline, Bézier, or NURBS curves to smooth speed transitions, thereby reducing the impact of acceleration/deceleration and maintaining continuous surface quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If speed command changes are made frequently to shorten machining time, then productivity is improved, but machining surface quality deteriorates due to cutting vibration from steep acceleration/deceleration
Solution Approach 1:
The patent implements dynamic speed adjustment by generating continuous commanded speed values through parametric curves (B-spline, Bézier, or NURBS) that smoothly transition between speed targets. The control unit calculates commanded speed at each interpolation unit based on position feedback, creating a dynamic speed profile that adapts to instantaneous machining conditions rather than using fixed step changes.
Solution Approach 2:
The system changes the parameter representation of speed control from discrete step commands to continuous parametric functions. By representing speed as a function of position through parametric curves and using interpolation units smaller than command blocks, the system transforms abrupt parameter changes into smooth transitions, resolving the contradiction between speed variation and surface quality.
2Manufacturing precision
If acceleration/deceleration is controlled to suppress impact, then machining surface quality is maintained, but machining time increases
Solution Approach 1:
The patent introduces a new dimension to speed control by using parametric curves that define speed as a continuous function of position rather than time or discrete commands. This dimensional transformation allows the system to optimize both surface quality and machining time by finding the optimal speed profile along the toolpath, rather than being constrained by traditional acceleration profiles.
Solution Approach 2:
The system replaces traditional mechanical acceleration control with computational parametric curve evaluation. Instead of relying on mechanical inertia and fixed acceleration rates, the control unit calculates commanded speed through software-based parametric functions, enabling more precise and flexible speed management that optimizes both quality and efficiency.
3Productivity
If high speed acceleration/deceleration is used for efficient machining, then productivity is improved, but tool life reduces due to increased machining load and cutting vibration
Solution Approach 1:
The system performs preliminary action by pre-calculating the commanded speed profile using parametric curves before actual machining begins. The control unit evaluates the parametric equations to determine optimal speed at each interpolation unit in advance, allowing the machine to follow a pre-planned smooth speed trajectory that prevents excessive machining load and vibration before they occur.
Data Source
AI summary
Provided are a numerical controller, a numerical control method, and a numerical control program capable of suppressing reduction in machining surface quality while increasing machining efficiency. A numerical controller comprises: a program analysis unit that analyzes a machining program for controlling a machine tool and calculates a cumulative moving distance for each command block based on a designated coordinate; a control point generation unit that generates, based on the moving distance and a designated speed for each command block, a control point as a set of the moving distance and the speed at a start point and an end point in the command block; a commanded speed generation unit that generates a parametric curve defining a commanded speed for the moving distance based on the control points; and a commanded speed output unit that outputs the generated commanded speed per interpolation unit.