Machine Tool Spindle Speed Control for Chatter Vibration Reduction
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Solution Overview
Problem
Existing machine tools face challenges in easily setting rotation speeds to efficiently reduce chatter vibration during threading operations, as the optimal variation width of rotation speed is not clearly defined, and excessive variation can result in actual rotation speeds exceeding the workpiece's upper limit, leading to ineffective vibration reduction.
Innovation Solution
A machine tool with a gripping unit, processing control unit, rotation speed control unit, and rotation speed calculation unit that varies the workpiece and tool rotation speed based on predefined conditions to minimize chatter vibration, using a display unit to guide adjustments of reference rotation speed and variation width to ensure the varied maximum speed does not exceed the upper limit, and automatically adjusts parameters to reduce vibration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the variation width of rotation speed is increased to reduce chatter vibration, then the chatter vibration reduction effect is improved, but the varied maximum speed may exceed the upper limit rotation speed of the workpiece
Solution Approach 1:
The patent implements dynamic adjustment of rotation speed variation width based on workpiece characteristics. The control unit calculates appropriate variation width considering the upper limit rotation speed of each workpiece, allowing the system to adaptively optimize vibration reduction while respecting speed constraints. This resolves the contradiction by making the variation width dynamic rather than fixed, enabling effective chatter reduction without exceeding operational limits.
Solution Approach 2:
The patent changes the parameter of rotation speed variation width according to workpiece-specific upper limit speeds. By adjusting this parameter within acceptable ranges for different workpieces, the system achieves effective chatter vibration reduction while ensuring the varied maximum speed does not exceed the upper limit rotation speed. This parameter adaptation resolves the contradiction between vibration reduction effectiveness and speed constraints.
2Adaptability or versatility
If the rotation speed variation width is set without clear guidelines, then the system flexibility is maintained, but the ease of operation deteriorates as workers struggle to set appropriate parameters
Solution Approach 1:
The patent implements a self-service mechanism where the control unit automatically calculates and determines appropriate rotation speed variation width based on workpiece characteristics and upper limit speeds. Workers simply need to input basic parameters, and the system autonomously optimizes the variation width to reduce chatter vibration effectively. This eliminates the need for workers to manually seek and set complex parameters, greatly improving ease of operation while maintaining adaptability.
Solution Approach 2:
The patent performs preliminary calculations of appropriate rotation speed variation width before actual machining operations. The control unit pre-determines optimal parameters based on workpiece characteristics and upper limit speeds, so that when machining begins, the system is already configured with optimal settings. This preliminary parameter determination simplifies operator tasks while ensuring effective chatter vibration reduction.
3Object-affected harmful factors
If the command rotation speed exceeds the upper limit rotation speed, then the theoretical vibration reduction capability is improved, but the actual rotation speed is limited causing ineffective vibration reduction
Solution Approach 1:
The patent implements feedback control where the control unit continuously monitors whether the commanded rotation speed exceeds the upper limit. When the calculated varied maximum speed would exceed the upper limit rotation speed, the system adjusts the variation width or reference speed to ensure the commanded speed remains within acceptable limits. This feedback mechanism ensures that the actual rotation speed matches the commanded speed, maintaining reliable chatter vibration reduction effectiveness.
Data Source
AI summary
A main spindle controller of a machine tool varies a rotation speed of a main spindle that grips a workpiece to a varied maximum speed higher than a reference rotation speed set value as a set value of a reference rotation speed by a variation width set value as a set value of a variation width or a varied minimum speed lower than the reference rotation speed set value by the variation width set value in units of the tool path. At the same time, the main spindle controller refers to speed condition information that indicates a condition of the preliminarily stored reference rotation speed and variation width assuming that a chatter vibration is to be reduced, and when at least one of the reference rotation speed set value and the variation width set value does not satisfy the condition of the speed condition information.