Spindle Speed Ramping During Cutting to Suppress Chatter
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Solution Overview
Problem
Conventional machining tools experience regenerative chatter vibrations due to fluctuations in cutting force, which deteriorate finishing accuracy and can chip the cutting tool, especially when the spindle rotation speed is periodically changed in a sinusoidal manner, resulting in an ineffective suppression of these vibrations.
Innovation Solution
A machining apparatus and method that incorporate a rotation mechanism with acceleration and deceleration control for the spindle, where the cutting tool is brought into contact with the workpiece after the spindle starts rotating, and the cutting process is completed while the spindle is under acceleration or deceleration, ensuring the current speed is either higher or lower than the previous rotation speed, thereby maintaining a speed variation ratio greater or less than 1 to suppress chatter vibrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the rotation speed of the spindle is periodically changed in a sinusoidal manner, then the regenerative chatter vibrations are suppressed to some extent, but the speed ratio becomes close to 1 before and after speed switches, reducing the suppression effect
Solution Approach 1:
The patent applies dynamics by continuously changing the spindle rotation speed during the cutting process rather than using periodic sinusoidal variations. The rotation speed is dynamically adjusted so that the current speed differs sufficiently from the speed one rotation before, maintaining a speed ratio that effectively suppresses regenerative chatter vibrations throughout the entire cutting process.
Solution Approach 2:
The patent changes the rotation speed parameter continuously during cutting, ensuring that the ratio between current speed and previous rotation speed remains significantly different from 1. This parameter change approach maintains effective vibration suppression throughout the cutting process, avoiding the inefficiency of periodic methods where the speed ratio approaches 1 near speed extrema.
2Productivity
If the cutting width is increased to improve material removal rate, then productivity increases, but regenerative chatter vibrations occur more frequently
Solution Approach 1:
The patent applies dynamics by continuously changing the spindle rotation speed during the cutting process rather than using periodic sinusoidal variations. The rotation speed is dynamically adjusted so that the current speed differs sufficiently from the speed one rotation before, maintaining a speed ratio that effectively suppresses regenerative chatter vibrations throughout the entire cutting process.
Solution Approach 2:
The patent changes the rotation speed parameter continuously during cutting, ensuring that the ratio between current speed and previous rotation speed remains significantly different from 1. This parameter change approach maintains effective vibration suppression throughout the cutting process, avoiding the inefficiency of periodic methods where the speed ratio approaches 1 near speed extrema.
Data Source
AI summary
A rotation controller controls a rotation mechanism for rotation of a spindle. A movement controller causes, while the spindle is rotating, a feed mechanism to bring a cutting tool into contact with a workpiece to cause the cutting tool to cut the workpiece. The rotation controller controls a spindle rotation speed so as to accelerate or decelerate the rotation of the spindle, and the movement controller brings the cutting tool into contact with the workpiece after the rotation controller starts the rotation of the spindle, and separates the cutting tool from the workpiece while the spindle rotation speed is put under the acceleration control or deceleration control exercised by the rotation controller.