Position Control Apparatus for Machine Tool Feed Shaft
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing position control apparatuses for machine tools face challenges in reducing position errors and low-frequency vibrations due to aging deterioration of the feed shaft mechanism, such as ball screw expansion and reduced tension, which affect the rigidity and cause mechanical resonance issues.
Innovation Solution
A position control apparatus that includes a motor position detector, a driven body position detector, and a deflection detector to calculate and adjust the proportional constant or time constant of the first-order lag circuit based on the deflection amount between the motor and driven body positions, thereby maintaining a larger gain margin at mechanical resonance frequencies and preventing low-frequency vibrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the position loop gain is increased to reduce position errors and improve transient response, then position control accuracy is improved, but low-frequency vibrations occur due to reduction in rigidity from aging deterioration
Solution Approach 1:
The patent implements dynamic adjustment of the position loop gain based on detected vibration levels. The control system continuously monitors vibration and adapts the gain parameter in real-time, transitioning from a static gain approach to a dynamic one that responds to changing mechanical conditions and aging deterioration.
Solution Approach 2:
The patent changes the control parameter (position loop gain) based on detected vibration states. By monitoring vibration levels and adjusting the gain parameter accordingly, the system optimizes position control accuracy while preventing low-frequency vibrations caused by aging-related rigidity reduction.
2Speed
If the speed loop gain is increased to suppress position errors during transient response, then response accuracy is improved, but the system becomes more sensitive to disturbances and vibrations
Solution Approach 1:
The patent introduces vibration detection feedback to the control system. By continuously monitoring vibration levels and feeding this information back to adjust the speed loop gain, the system maintains fast response capability while reducing sensitivity to disturbances and preventing vibration amplification.
3Productivity
If continuous operation is maintained to increase productivity, then output is improved, but aging deterioration accelerates causing rigidity reduction and vibrations
Solution Approach 1:
The control system performs self-diagnosis by detecting vibrations and automatically adjusting control parameters in response to aging deterioration. This self-service capability allows the system to maintain reliable operation throughout its service life without external intervention for parameter recalibration.
Solution Approach 2:
The patent detects early signs of aging deterioration through vibration monitoring and takes preliminary action by adjusting control parameters before significant performance degradation occurs. This preventive approach maintains mechanical reliability during continuous operation.
Data Source
AI summary
A deflection amount Ps representing a difference between a position detection value Pl of a driven body and a position detection value Pm of a motor is detected. A position calculator proportional constant Kp, a time constant Tp of a first-order lag circuit that inputs a the deflection amount Ps, and a time constant Tv of a first-order lag circuit that inputs a difference between a speed detection value Vl of the driven body and a speed detection value Vm of the motor are changed based on the deflection amount Ps.