Main Spindle Speed Variation Limits for Chatter Reduction
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Solution Overview
Problem
Existing methods for reducing chatter vibration in machine tools by varying the rotation speed of the main spindle face challenges in accurately setting the variation amplitude and cycle, often leading to excessive motor output restriction or failure to achieve optimal reduction effects due to inaccurate estimation of motor output limits.
Innovation Solution
A monitoring device and method that calculates a settable range for the rotation speed variation amplitude and cycle based on the difference between rotation speeds at different timings and the usage proportion of the motor's rated output, displaying an output limit line to guide optimal setting values for reducing chatter vibration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the output limit line is displayed using the maximum value of the rotation speed, then the motor output is restricted more than necessary, but the estimation accuracy is improved
Solution Approach 1:
The patent changes the parameter used for displaying the output limit line from the maximum rotation speed value to the median rotation speed value. This parameter change resolves the contradiction by providing a more accurate estimation of the motor output limit without causing excessive restriction of the motor output, as the median value better represents the actual operational characteristics of the motor under varying rotation speed conditions.
2Reliability
If the variation condition is set in accordance with the output limit line displayed using the maximum value of the rotation speed, then the motor output is restricted more than necessary, but the variation cannot be performed with the setting value
Solution Approach 1:
The patent changes the display parameter from maximum rotation speed to median rotation speed for the output limit line. This enables operators to set variation conditions with higher reliability, as the median-based limit accurately reflects motor capabilities under actual operating conditions, allowing variation to be performed successfully with the set values while maintaining ease of operation.
3Manufacturing precision
If the rotation speed variation is performed to reduce chatter vibration, then the surface accuracy is improved, but the setting of variation amplitude and cycle becomes difficult
Solution Approach 1:
The patent implements a feedback mechanism by displaying the output limit line on the variation diagram based on median rotation speed. This visual feedback guides operators in setting appropriate variation amplitude and cycle parameters, making it easier to achieve optimal settings for reducing chatter vibration and improving surface accuracy without requiring complex manual calculations or trial-and-error adjustments.
Data Source
AI summary
A monitoring device of a main spindle rotation speed in a machine tool displays a variation state of the rotation speed by a rotation speed variation unit using a display unit in the machine tool. The monitoring device includes a variation value setting unit, a drawing unit, a first display unit, and a settable range calculating unit. The settable range calculating unit is configured to calculate a settable range of a variation amplitude and a variation cycle based on a calculation formula. The calculation formula includes the variation cycle, a difference between a first rotation speed and a second rotation speed at mutually different timings among the rotation speeds varied relative to a reference rotation speed, an inertia of a rotating body, a rated output of a motor that drives a main spindle, and a usage proportion to the rated output of the motor.