Machine Tool Speed Control for Shaft Vibration
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Solution Overview
Problem
Horizontal boring machines face issues with vibration and bearing damage due to changes in main shaft feed length, leading to decreased processing accuracy and potential bearing damage, especially when high-speed processing is required.
Innovation Solution
A machine tool with a control system that adjusts the upper limit of the main shaft's revolution speed based on its feeding length, using a support portion, first and second driving units, and a memory unit to store and associate the upper limit values, ensuring the revolution speed does not exceed critical limits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the main shaft is fed to a long length from the support portion, then the processing versatility is improved, but the main shaft vibrates due to exceeding critical revolution speed
Solution Approach 1:
The control portion dynamically adjusts the upper limit value of revolution speed based on the feed amount of the main shaft. When the feed amount increases, the system automatically lowers the revolution speed limit to prevent vibration, and when the feed amount decreases, it raises the limit to allow higher speeds. This dynamic adaptation resolves the contradiction between processing versatility and main shaft stability.
2Productivity
If the revolution speed of the main shaft is increased for high-speed processing, then the productivity is improved, but the ball bearing is likely to be damaged due to excessive load
Solution Approach 1:
The control portion continuously monitors the feed amount of the main shaft and uses this feedback to adjust the upper limit value of revolution speed. This feedback mechanism ensures that the revolution speed never exceeds the critical speed that would damage the ball bearing, while still allowing the system to operate at the highest possible speed within safe limits, thus maintaining both productivity and reliability.
3Stability of the object's composition
If the upper limit value of revolution speed is reduced to prevent vibration, then the main shaft stability is improved, but the processing time increases
Solution Approach 1:
Rather than using a fixed reduced speed limit, the control portion dynamically adjusts the upper limit value of revolution speed based on the actual feed amount. This allows the system to operate at high speeds when the feed amount is small (maintaining short processing time) and automatically reduces speed only when necessary (when feed amount is large and vibration risk exists), thus minimizing processing time while maintaining stability.
Data Source
AI summary
A machine tool which processes a machine target object using a main shaft which revolves, the machine tool includes a support portion which supports the main shaft; a first driving unit which revolves the main shaft about a first axis; a second driving part which feeds the main shaft from the support portion in a direction of the first axis; a control part which changes an upper limit value of a revolution speed of the main shaft according to a feeding length of the main shaft fed from the support portion; and a memory unit which associates and stores the upper limit value of the revolution speed and the feeding length.