Lathe Bar Re-Gripping Control to Suppress Runout
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Solution Overview
Problem
The existing machine tool systems face issues with machining quality degradation due to bar runout during the grip change process, which can lead to defective products, and reducing spindle revolutions to mitigate this problem decreases machining speed and quality.
Innovation Solution
A machine tool system with a gripping position selecting unit that chooses a special gripping position different from the predetermined position, based on conditions such as spindle movement, bar properties, and vibration detection, to minimize runout and include a steadying apparatus and pusher positioning to suppress bar rotation and vibration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the spindle maintains high rotation speed during grip change, then machining speed and productivity are improved, but bar runout and vibration increase causing machining quality degradation
Solution Approach 1:
The system performs preliminary detection of bar runout conditions before the grip change operation. The runout detection unit measures bar runout during the grip change, and based on this detection result, the control unit determines whether to execute the grip change. This preliminary detection prevents grip changes when runout would cause quality degradation, while allowing continuous operation when conditions are favorable, thus maintaining high productivity without sacrificing quality.
Solution Approach 2:
The system implements a feedback mechanism where the runout detection unit continuously monitors bar runout during grip change operations. The control unit uses this feedback information to make real-time decisions about whether to proceed with grip change. This closed-loop control allows the system to maintain high machining speeds while dynamically adjusting grip change execution based on actual runout conditions, resolving the contradiction between productivity and quality.
2Manufacturing precision
If the spindle reduces rotation speed during grip change, then bar runout and vibration are suppressed maintaining machining quality, but machining speed and productivity decrease
Solution Approach 1:
The system dynamically adjusts grip change execution based on real-time runout detection rather than using a fixed speed reduction strategy. The control unit determines whether to execute grip change based on detected runout conditions, allowing the system to operate at high speeds when conditions permit and skip grip changes when runout would occur. This dynamic approach maintains machining quality without the continuous productivity loss associated with speed reduction.
Solution Approach 2:
The system changes the operational parameter from continuous speed reduction to discrete grip change execution decisions based on runout detection. Instead of maintaining reduced speed throughout, the system operates at full speed and selectively executes grip changes only when runout conditions are favorable. This parameter change approach maintains machining quality while preserving overall machining speed and productivity.
3Productivity
If grip change is executed frequently, then continuous production is maintained, but bar runout causes machining quality degradation
Solution Approach 1:
The runout detection unit provides continuous feedback on bar runout conditions during grip change operations. The control unit uses this feedback to intelligently determine whether to execute each grip change, rather than following a fixed schedule. This allows the system to maintain continuous production by executing grip changes when conditions are favorable while skipping them when runout would occur, thus maintaining both productivity and quality.
Solution Approach 2:
The system performs self-monitoring of runout conditions and self-adjusts grip change execution accordingly. The runout detection unit and control unit work together to automatically determine the optimal timing for grip changes without external intervention. This self-service mechanism ensures continuous production while preventing quality degradation through intelligent, condition-based grip change execution.
Data Source
Figure 1
Figure 2
Figure 3A~3B
AI summary
A lathe system 1 includes a spindle 25 capable of gripping a bar W and moving back and forth in an axial direction of the bar W and a tool post 27 to which a first tool T1 is attached. The lathe system 1 can manufacture a plurality of products having an identical shape from the bar W by repeating a machining of the bar W, a cutting off of a machined portion of the bar W, and a grip change by the spindle 25, the grip change by the spindle 25 comprising releasing the bar W, moving back, and re-gripping the bar W at a predetermined gripping position. The lathe system 1 further includes a gripping position selecting unit 20b capable of selecting a special gripping position at which the spindle 25 re-grips the bar W when a state of the machine tool system meets a predetermined condition, the special gripping position being different from the predetermined gripping position.