Machine Tool Rotation Speed Control for Threading Accuracy
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Solution Overview
Problem
Machine tools face challenges in reliably performing cutting at high rotation speeds, particularly in specific tool passes, which can lead to chatter vibrations and degrade cutting surface accuracy due to uncertainty about initial spindle rotation speed.
Innovation Solution
A machine tool system with a holding device, tool, machining control unit, rotation-speed control unit, and specific-rotation-speed computing section that determines whether the first tool pass should be at high or low rotation speed to ensure cutting in specific tool passes, especially the last pass, is performed at high speed, thereby suppressing chatter vibrations and maintaining accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the main spindle rotation speed is changed in every tool pass during a threading cycle, then chatter vibrations can be suppressed, but it becomes difficult to determine whether the first cutting should be at low or high rotation speed, potentially causing the last tool pass to be performed at low speed which degrades cutting surface accuracy
Solution Approach 1:
The invention performs preliminary calculation before the threading cycle starts to determine the optimal rotation speed pattern. The rotation speed computing section calculates which rotation speed (high or low) should be applied in the first tool pass based on the total number of tool passes and the requirement that the last pass must be at high speed. This preliminary determination ensures that the rotation speed pattern is optimized in advance, guaranteeing that the last tool pass occurs at high rotation speed while still achieving chatter vibration suppression through alternating speeds.
2Object-affected harmful factors
If cutting is performed alternately at low and high rotation speeds, then chatter vibrations are suppressed, but cutting surface accuracy may be degraded if the last tool pass is performed at low rotation speed
Solution Approach 1:
The rotation-speed computing section performs preliminary calculation to determine the optimal rotation speed assignment before machining begins. By calculating the total number of tool passes and determining the appropriate starting speed, the system ensures that the alternating speed pattern will result in the last pass being performed at high rotation speed. This preliminary planning maintains the benefits of alternating speeds for chatter suppression while guaranteeing high-quality finishing in the final pass.
Data Source
AI summary
A machine tool includes a first-pass rotation speed computing section. The first-pass rotation speed computing section automatically decides whether the main spindle rotation speed in the first pass should be a high rotation speed or a low rotation speed so that cutting in the last tool pass is performed at the high rotation speed. Thus, cutting of the last tool pass at the low rotation speed can be reliably prevented.