Corner Feed Rate Planning for Vibration-Stable Tool Paths
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Solution Overview
Problem
During machining of a workpiece, especially at corner parts where the tool direction changes discontinuously, large inertia forces occur, leading to vibrations and adversely affecting the quality of the machined surface.
Innovation Solution
A control device is implemented that includes a corner detection unit, first and second rate-planning units, an instruction generation unit, and an instruction rate generation unit. These components work together to generate deceleration and acceleration plans, overlap these plans to create a curve instruction path, and adjust feed rates to ensure that the acceleration on this path does not exceed a predetermined allowable acceleration, thereby minimizing vibrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the tool is controlled to move at a low feed rate at corner parts, then vibrations are reduced, but the machining time increases and productivity decreases
Solution Approach 1:
The patent applies dynamics by continuously changing the feed rate dynamically based on the curvature of the tool path. Instead of maintaining a uniformly low feed rate, the system adjusts the feed rate in real-time: reducing it only when necessary (at high-curvature corner parts) and maintaining higher rates elsewhere, thereby minimizing vibration while preserving productivity
Solution Approach 2:
The patent changes the feed rate parameter adaptively according to the local geometric characteristics (curvature) of the tool path. By calculating the curvature at each point and adjusting the feed rate accordingly, the system optimizes the balance between vibration control and machining efficiency
2Manufacturing precision
If the feed rate is reduced at corner parts, then surface quality improves, but the inertia force on control axes increases
Solution Approach 1:
The patent applies preliminary action by pre-calculating the curvature of the tool path and planning the feed rate changes in advance. The curvature information is computed beforehand, and the feed rate profile is optimized based on this pre-analyzed geometric data, allowing smooth transitions that minimize inertia forces while ensuring surface quality
Solution Approach 2:
The system dynamically adjusts the feed rate based on real-time curvature information, creating a smooth transition profile that avoids abrupt changes. This dynamic adaptation ensures that inertia forces remain within acceptable limits while achieving the desired surface quality at corner parts
3Object-affected harmful factors
If the tool moves along a NURBS curve to continuously change direction, then vibration is prevented, but the device complexity increases
Solution Approach 1:
The patent replaces complex mechanical control mechanisms with computational methods. Instead of using complex hardware to physically guide the tool along NURBS curves, the system uses software-based curvature calculation and feed rate optimization to achieve smooth motion, thereby reducing mechanical complexity while maintaining vibration control
Solution Approach 2:
The patent simplifies the control system by focusing on parameter optimization (feed rate) rather than complex path generation. By maintaining the original tool path geometry and only adjusting the feed rate parameter based on curvature, the system achieves vibration prevention without requiring complex NURBS curve generation capabilities
Data Source
AI summary
Provided is a control device including a corner detection unit that detects a command for a corner portion; a command generation unit that generates a curve command path and first command speed information indicating a first provisional feed speed by overlapping a feed speed when a tool moves toward the corner portion and a feed speed when the tool moves away from the corner portion; a second speed planning unit that generates second command speed information indicating a second provisional feed speed; and a command speed generation unit that generates third command speed information indicating an actual feed speed when the tool is to actually move on the curve command path.