Machining Velocity Profile Control for Jerk Reduction
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Solution Overview
Problem
Existing machining processes using machine tools, such as grinding, experience abrupt changes in tool velocity, leading to high jerk characteristics, sudden bursts in grinding power, and machining errors due to step changes in feed rates, which result in time-consuming delays and potential damage to the workpiece.
Innovation Solution
A control arrangement that maintains a continually decreasing relative velocity between the tool and workpiece throughout the machining process, minimizing abrupt accelerations and decelerations, and allowing for continuous material removal with adjustments based on real-time measurements to ensure precise finishing without pauses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If step changes in feed rate are used to control machining phases, then material removal rate is controlled and machining errors are minimized, but abrupt velocity changes cause high jerk characteristics, sudden bursts in grinding power, and time-consuming delays
Solution Approach 1:
The patent applies dynamics by transitioning from static, discrete feed rate steps to a dynamic, continuous velocity profile. The feed rate is no longer held constant in phases but varies continuously according to a predetermined profile that adjusts the tool velocity smoothly as a function of position or time, eliminating abrupt changes while maintaining precision control throughout the machining process.
Solution Approach 2:
The patent implements parameter changes by modifying the velocity parameter continuously rather than in discrete steps. The feed rate is changed as a continuous variable following a predetermined profile, allowing smooth transitions between different machining stages while maintaining optimal material removal rates and avoiding the time losses associated with abrupt parameter changes.
2Productivity
If step changes in feed rate are used to control machining phases, then material removal rate is controlled, but abrupt accelerations and decelerations cause high jerk characteristics and sudden bursts in grinding power
Solution Approach 1:
The patent applies dynamics by implementing continuous velocity adjustment rather than static phase-based feed rates. The tool velocity is dynamically modified according to a predetermined profile that ensures smooth transitions, eliminating the abrupt accelerations and decelerations that cause harmful jerk characteristics and power bursts while maintaining effective material removal.
Solution Approach 2:
The patent applies beforehand cushioning by pre-defining a velocity profile that anticipates and cushions against abrupt changes. The predetermined profile ensures that velocity transitions are smoothed in advance, preventing sudden bursts in grinding power and reducing jerk characteristics before they can occur during the machining process.
3Reliability
If feed is halted and retraction is performed to avoid workpiece damage, then workpiece protection is achieved, but machining time increases due to suspension and settling delays
Solution Approach 1:
The patent applies continuity of useful action by maintaining continuous material removal throughout the machining process without halting the feed. The predetermined velocity profile ensures that the tool velocity smoothly approaches zero as the workpiece nears its final dimensions, eliminating the need for suspension and retraction while protecting workpiece integrity through controlled, continuous operation.
Solution Approach 2:
The patent applies preliminary action by pre-calculating and implementing a velocity profile that anticipates the completion of machining. The profile is designed in advance to automatically reduce velocity as the workpiece approaches its final size, preventing damage before it occurs and eliminating the need for post-hoc suspension and retraction operations.
Data Source
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AI summary
A method of machining a workpiece using a machine tool, the machine tool comprising a tool mount carrying a tool, a workpiece mount carrying a workpiece, a drive mechanism for moving at least one of the tool mount and the workpiece mount relative to the other, and a control arrangement for controlling the drive mechanism. The method comprises moving at least one of the tool mount and the workpiece mount with the drive mechanism under the control of the control arrangement so that the tool contacts a portion of the workpiece to commence a machining operation, and the tool then removes material from the portion of the workpiece until completion of the machining operation, the movement being such that the relative velocity between the tool and the workpiece decreases continuously during the majority of the time that the tool and the workpiece are in contact with each other during the machining operation.