Oscillating Drive Axis Phase Control for Vibration-Safe Machining
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Solution Overview
Problem
Machine tools with oscillating cutting mechanisms using multiple drive axes can experience vibrations, leading to abnormal loads, increased tool wear, and reduced machining precision due to overlapping oscillations and periodic speed variations.
Innovation Solution
A numerical control device that controls at least two oscillating drive axes to maintain a fixed phase difference in their periodic variable components, ensuring that the frequency of velocity changes for each axis is equal, thereby preventing simultaneous force application in the same direction and reducing overall vibration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple oscillating drive axes operate simultaneously with the same oscillation period, then machining productivity is improved through parallel processing, but machine tool vibration increases due to overlapping oscillations
Solution Approach 1:
The patent applies periodic action by controlling multiple oscillating drive axes to operate with different oscillation periods. Specifically, the first oscillating drive axis oscillates with a period T1, while the second oscillating drive axis oscillates with a period T2 where T1 ≠ T2. This differential periodic operation prevents simultaneous oscillations from overlapping and causing resonant vibration, thereby maintaining machine stability while enabling parallel machining of multiple workpieces
Solution Approach 2:
The patent employs asymmetry by introducing asymmetric oscillation parameters among multiple drive axes. The oscillation periods are deliberately made different (T1 ≠ T2), creating an asymmetric operational pattern that prevents synchronized vibration. This asymmetric control strategy allows multiple tools to operate in parallel without their oscillations reinforcing each other, thus resolving the contradiction between productivity and vibration
2Loss of substance
If oscillating cutting is implemented to shred shavings, then chip removal is improved, but tool wear increases due to repeated acceleration and deceleration
Solution Approach 1:
The patent utilizes periodic action to implement oscillating cutting where the cutting tool periodically changes its feed speed, accelerating and decelerating in a controlled manner. This periodic speed variation causes the cutting tool to reciprocally move relative to the workpiece, effectively shredding long shavings into shorter segments that are easier to remove. By optimizing the oscillation period and amplitude, the system achieves effective chip breakdown while managing the cumulative wear from repeated acceleration cycles
3Device complexity
If multiple drive axes oscillate with the same phase, then control simplicity is maintained, but machining precision deteriorates due to cumulative vibration effects
Solution Approach 1:
The patent applies asymmetry by controlling multiple oscillating drive axes to operate with different phases and/or different oscillation periods. Instead of maintaining simple in-phase operation, the system introduces phase differences between the first oscillating drive axis and the second oscillating drive axis. This asymmetric phase control prevents the oscillations from accumulating constructively, thereby maintaining machining precision while managing the increased control complexity through systematic phase management
Data Source
AI summary
A numerical control device according to an embodiment of the present disclosure is a numerical control device for controlling at least two oscillating drive axes which linearly drive so as to cause mutually differing targets to change speed regularly at a fixed period, based on a machining program, in which the numerical control device controls the at least two oscillating drive axes so as to keep fixed a phase difference of periodic variable components of the at least two oscillating drive axes.