Machine Tool Spindle Speed Control for Chatter Vibration Suppression
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Solution Overview
Problem
Existing machine tool controllers are ineffective in reliably eliminating or minimizing chatter vibrations during cutting operations, often requiring skilled intervention and relying on complex calculations or data accumulation for optimal machining conditions.
Innovation Solution
A controller system that detects chatter vibrations using acceleration sensors and load detection, and automatically adjusts the spindle rotational speed within predetermined limits by generating a random change amount to eliminate or minimize vibrations, eliminating the need for stability lobe diagrams and reducing calculation complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If random spindle speed adjustment is implemented to eliminate chatter vibrations, then vibration elimination effectiveness is improved, but control system complexity increases
Solution Approach 1:
The patent applies dynamics by making the spindle speed adjustable and variable during machining operations. The control device dynamically modifies the spindle speed from its originally set value by adding a random adjustment value, transforming a static speed parameter into a dynamic one that adapts to prevent chatter vibrations effectively
Solution Approach 2:
The patent changes the parameter of spindle speed from a fixed value to a variable value through random adjustment. By modifying the speed parameter dynamically during operation based on detected vibration conditions, the system achieves better vibration elimination while the control device manages the complexity of this parameter change
2Manufacturing precision
If stability lobe diagrams and complex calculations are used to determine optimal machining conditions, then machining precision is improved, but calculation complexity and data accumulation requirements increase
Solution Approach 1:
The control device performs self-service by automatically detecting chatter vibrations through acceleration sensors and autonomously adjusting spindle speed to eliminate them. This eliminates the need for operators to manually create stability lobe diagrams or perform complex calculations, as the system serves itself by sensing and responding to vibration conditions in real-time
Solution Approach 2:
The patent replaces the mechanical/computational approach of creating stability lobe diagrams with an sensor-based detection system. Instead of using complex mathematical models and diagrams, the system uses acceleration sensors to directly detect vibrations and triggers automatic speed adjustment, substituting theoretical calculations with practical sensing and control
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 system effectively and automatically minimizes chatter vibrations during cutting operations, reducing the reliance on skilled operators and data accumulation, while simplifying the calculation process and ensuring consistent performance across various tools and workpiece materials.
Implementation Method 1
a sensor detects during manufacturing when chatter vibrations start to appear and when they stop
Data Source
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AI summary
A machine tool (100) includes: a tool spindle (112), on which a cutting tool (CT) is mounted; and a controller (1). The controller (1) includes a control circuit (10), a determination circuit (30), and a setting circuit (40). When a chatter vibration is determined as occurring while the tool spindle (112) is rotating to cut a workpiece (W), the control circuit (10) determines a change amount (V) randomly from a range between an upper limit (UL) and a lower limit (LL), and rotates the tool spindle (112) at a second rotational speed (RS2), which is obtained by changing a first rotational speed (RS1) by the change amount (V).