Feed Shaft Forced Vibration for Chatter Suppression
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Solution Overview
Problem
Existing methods for suppressing chatter vibration and tool chipping during deep cutting in machine tools are either complex, require excessive load on spindle motors, or are not suitable for deep cutting, and fail to uniformly distribute cutting forces across tool edges, leading to inefficient machining and potential tool chipping.
Innovation Solution
A machining vibration suppressing method and apparatus that applies forced vibration at specific frequencies and amplitudes to the feed shaft during machining, synchronizing or shifting the vibration frequency with respect to the tool's rotation speed to uniformly distribute cutting forces and cancel tool runout, thereby suppressing chatter vibration and tool chipping.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the amount of cutting is increased during machining, then productivity is improved, but chatter vibration occurs resulting in degraded machined surface
Solution Approach 1:
The patent applies ultrasonic vibration to the tool or workpiece during machining to suppress chatter vibration. By introducing high-frequency mechanical vibration, the system modifies the cutting process to eliminate harmful chatter vibrations that degrade machined surface quality, thereby enabling higher cutting amounts without sacrificing surface finish.
Solution Approach 2:
The patent employs periodic variation of cutting parameters or application of periodic ultrasonic vibration to prevent chatter vibration. This periodic action disrupts the self-excited vibration cycle, allowing increased cutting depth while maintaining surface quality by preventing the buildup of chatter vibrations.
2Reliability
If a sensor that detects chatter and a complicated control device are used to suppress chatter vibration, then chatter vibration is suppressed, but device complexity increases
Solution Approach 1:
The patent utilizes the inherent properties of the machining system and the physics of ultrasonic vibration to achieve chatter suppression without requiring external sensors or complex control algorithms. The ultrasonic vibration source directly modifies the cutting process, allowing the system to self-regulate and suppress chatter through the physical characteristics of the vibration rather than through sensing and feedback control.
3Reliability
If the rotation speed of the main spindle is varied by a certain amount of displacement and certain period to suppress chatter, then chatter vibration is suppressed, but excessive load is applied to the main spindle motor
Solution Approach 1:
Instead of varying the main spindle rotation speed, the patent applies ultrasonic vibration at a different frequency range to the tool or workpiece. This approach suppresses chatter vibration through high-frequency mechanical oscillation without requiring changes to the main spindle speed, thereby avoiding excessive load on the main spindle motor while achieving effective chatter suppression.
4Reliability
If a unit that generates ultrasonic vibration is attached to a feed shaft to apply high frequency minute vibration, then chatter vibration is suppressed, but the method is not suitable for deep cutting
Solution Approach 1:
The patent modifies the parameters of ultrasonic vibration, specifically adjusting the amplitude and frequency, to make the technique suitable for deep cutting operations. By optimizing these parameters, the ultrasonic vibration provides sufficient energy to suppress chatter even during deep cutting where cutting forces are higher, thereby extending the applicability of the method to various cutting depths.
5Reliability
If trochoid machining is used to reduce the time for which an edge contacts the workpiece, then chatter vibration is suppressed, but the cutting amount cannot be increased due to program changes required
Solution Approach 1:
The patent applies ultrasonic vibration directly to the tool or workpiece during conventional machining operations to suppress chatter vibration. This approach eliminates the need for complex trochoid path programming while effectively reducing chatter, thereby maintaining the ability to perform deep cutting and increase cutting amount without being constrained by program complexity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The method effectively suppresses chatter vibration and tool chipping by periodically varying the feed rate and uniformly distributing cutting forces, allowing for increased cutting capacity and extended tool life without increasing cutting resistance or requiring complex sensor systems.
Implementation Method 1
applying forced vibration at a predetermined amplitude and a predetermined frequency of vibration to feed operation for a feed shaft during machining
Implementation Method 2
the frequency of vibration of the forced vibration is a frequency of vibration that is equal to a rotation speed of the tool... the forced vibration can be caused to cancel the influence of the amount of tool runout
Data Source
AI summary
An apparatus includes an external input device that allows setting of the amount of runout and the phase of each cutting edge, a computation device that acquires the rotational phase of a tool and that computes the angular velocity and the phase of vibration of two, X-axis and Y-axis, feed shafts on the basis of the input amount of runout and angular velocity of each cutting edge to generate a feed shaft control signal, and a numerical control device that controls feed in the X-axis and the Y-axis directions. The numerical control device relatively vibrates a workpiece in synchronization with the angular velocity of the tool on the basis of the results of computation performed by the computation device.