Machine Tool Drive Speed Control for Vibration Damping
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Solution Overview
Problem
Core drilling machines experience unwanted oscillations and vibrations during the drilling process, leading to mechanical and dynamic loads, potential damage, safety risks, and inefficient drilling due to reduced rotational speed to mitigate these issues.
Innovation Solution
A method for controlling a machine tool that involves setting the drive speed to a first value, measuring and filtering signal amplitudes, reducing speed when predetermined magnitudes are exceeded, and incrementally increasing speed only after amplitudes return within set limits for a predetermined time, using a control unit and acceleration sensor to manage vibrations and resonances.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the rotational speed of the drilling drive is reduced to avoid oscillations and vibrations, then the mechanical and dynamic loads are reduced, but the drilling advance becomes slower and the overall drilling process is less efficient
Solution Approach 1:
The patent applies dynamics by continuously monitoring vibration amplitudes during drilling and dynamically adjusting the rotational speed in real-time. The control unit increases speed when vibrations are low and reduces speed when vibrations exceed thresholds, allowing the system to operate at optimal speeds rather than maintaining a consistently reduced speed. This dynamic control resolves the contradiction by enabling high productivity during stable drilling while preventing harmful oscillations when they occur.
Solution Approach 2:
The patent implements feedback control by using sensors to detect vibration amplitudes and feeding this information back to the control unit, which then adjusts the rotational speed accordingly. The control unit compares measured vibration levels against predetermined thresholds and automatically modifies drilling parameters. This closed-loop feedback system resolves the contradiction by continuously optimizing the balance between drilling efficiency and vibration avoidance based on actual drilling conditions.
2Strength
If the rotational speed is continuously reduced to prevent resonances, then the mechanical loads on drilling tools are minimized, but the drilling process time is significantly extended
Solution Approach 1:
The patent applies periodic action by implementing cyclical monitoring and adjustment of drilling parameters based on vibration feedback. The control unit periodically checks vibration amplitudes and adjusts rotational speed in response to changing drilling conditions. This periodic control allows the system to maintain high speeds during stable periods while briefly reducing speed when resonances occur, thereby minimizing both mechanical loads and time loss compared to continuous speed reduction.
Solution Approach 2:
The patent utilizes parameter changes by dynamically modifying the rotational speed parameter based on real-time vibration measurements. Instead of maintaining a fixed reduced speed, the system changes the speed parameter adaptively - increasing it when vibrations are acceptable and decreasing it when resonances are detected. This parameter optimization resolves the contradiction by achieving the necessary load reduction only when required, thus minimizing drilling time loss.
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
This method effectively reduces oscillations and vibrations, enhancing the safety and efficiency of the drilling process by minimizing mechanical loads and maintaining optimal drilling speed, thereby preventing damage and ensuring precise hole angles.
Implementation Method 1
an acceleration along an impact axis of the machine tool is detected
Implementation Method 2
filtering the signal in a predetermined frequency range
Data Source
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AI summary
The invention relates to a method for controlling a machine tool comprising the method steps: setting the speed of a drive to a first value, measuring a first amplitude of a signal, filtering the signal in a frequency range, measuring a second amplitude of the filtered signal, reducing the speed of the drive to a second value when the first amplitude exceeds a first quantity and the second amplitude exceeds a second quantity, and progressively increasing the speed of the drive to the first value, wherein each step of increasing the speed only takes place after the first amplitude has remained below the first quantity and the second amplitude has remained below the second quantity for a period of time. A machine tool for application of this method, containing a drive for a tool, an acceleration sensor for measuring a first amplitude and a second amplitude of a signal, a filter for filtering the signal in a predetermined frequency range and a control unit for controlling at least the speed of the drive.