Main Spindle Fluctuation Control for Chatter Without Speed Shock
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Solution Overview
Problem
Existing methods to suppress regenerative self-excited chatter vibration in machine tools cause mechanical shocks and surface quality deterioration due to rapid changes in the rotation speed of the main spindle.
Innovation Solution
A control device that calculates and controls the rotation speed of the main spindle motor with a fluctuation command to gradually change the amplitude and/or frequency of periodic fluctuations, reducing the steepness of speed changes and minimizing adverse effects while maintaining chatter vibration suppression.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the rotation speed of the main spindle is made to periodically fluctuate to suppress regenerative self-excited chatter vibration, then the chatter vibration suppression effect is improved, but mechanical shock and surface quality deterioration occur due to rapid changes in rotation speed
Solution Approach 1:
The patent applies periodic fluctuation of the main spindle rotation speed to suppress regenerative self-excited chatter vibration. The rotation speed is made to periodically fluctuate around a target speed, creating a periodic action that disrupts the chatter vibration mechanism while maintaining overall machining stability.
Solution Approach 2:
The patent dynamically adjusts the rotation speed of the main spindle by superimposing a fluctuation component on the target speed. The fluctuation command is calculated based on the target speed and fluctuation conditions, allowing the system to adaptively control the rotation speed to suppress chatter while minimizing adverse effects through gradual changes in amplitude and frequency.
Data Source
AI summary
Provided is a control device for a machine tool capable of reducing adverse effects due to rapid changes in periodic fluctuations in the rotation speed of a main spindle while maintaining an effect of suppressing regenerative self-excited chatter vibration. This control device for a machine tool includes a fluctuation command calculation unit configured to calculate a fluctuation command based on a speed command for a main spindle motor of the machine tool and a fluctuation condition for causing a rotation speed of the main spindle motor to periodically fluctuate, and a speed control unit configured to control the rotation speed of the main spindle motor based on the speed command and the fluctuation command. The fluctuation command calculation unit is configured to calculate, when the fluctuation condition is changed, the fluctuation command in which an amplitude of the rotation speed that periodically fluctuates and/or a frequency of the rotation speed that periodically fluctuates gradually changes.