Motor Command Filtering for Smooth Oscillation Mode Switching
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Solution Overview
Problem
Conventional oscillation cutting techniques cause shocks in machine tools due to abrupt changes in acceleration during oscillation mode switching, leading to machining defects and tool entanglement.
Innovation Solution
A motor control device that includes an oscillation command calculation unit, a switching determination unit, a filter setting unit, a filter coefficient calculation unit, and a filter application unit to apply a filter to the motor command at the time of oscillation mode switching, reducing sharp acceleration changes and minimizing shock.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If oscillation mode switching is performed during oscillation cutting, then machining flexibility and adaptability are improved, but shock and vibration increase due to abrupt acceleration changes
Solution Approach 1:
The control device predicts future oscillation phases and determines optimal switching timings in advance, before actual mode transitions occur. This preliminary calculation allows the system to plan acceleration profiles that avoid abrupt changes, thereby reducing shock and vibration while maintaining machining flexibility
Solution Approach 2:
The system dynamically adjusts oscillation phases and switching timings based on real-time machining conditions. By making the switching timing variable rather than fixed, the system can adapt to changing conditions while maintaining smooth acceleration transitions, thus preserving both flexibility and reducing harmful vibrations
2Adaptability or versatility
If oscillation command is superimposed on movement command, then oscillation cutting function is achieved, but discontinuous command generation occurs at mode switching
Solution Approach 1:
The control device calculates and stores optimal switching timings and corresponding oscillation phases in advance, before mode transitions are executed. This preliminary preparation ensures that when switching occurs, the command transitions smoothly without discontinuities, maintaining both oscillation functionality and command stability
Solution Approach 2:
The system uses feedback from the current oscillation phase and machining state to determine appropriate switching timings. By continuously monitoring the system state and adjusting switching decisions accordingly, the system maintains command continuity while preserving oscillation cutting capabilities
Data Source
AI summary
The present invention provides a technology that can reduce a shock of a machine tool caused by a sharp change in acceleration at the time of oscillation mode switching in oscillation machining. A motor control device 1 comprises: an oscillation command calculation unit 12 that calculates an oscillation command from a movement command and an oscillation condition; an oscillation mode switching determination unit 32 that determines a timing of finishing the oscillation or switching a machining path; a filter time constant/application time setting unit 31 that sets a time constant τ and an application time to of a filter; a filter coefficient calculation unit 33 that calculates a filter coefficient K on the basis of the time constant τ set by the filter time constant/application time setting unit 31; and a filter application unit 34 that applies a filter having the filter coefficient K to a command for driving a motor 2 during the application time to when the oscillation mode switching determination unit 32 determines that the switching timing has been reached.