Numerical Control Device Dynamic Acceleration Adjustment
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Solution Overview
Problem
Numerical control devices face inefficiencies in dynamically adjusting acceleration and time constants during machining, leading to suboptimal cycle times, vibration suppression, and overload prevention, as they rely on pre-estimated workpiece weights and fixed time constants.
Innovation Solution
A numerical control device that monitors state quantities like inertia, load, and acceleration-deceleration factors in real-time, allowing for dynamic adjustment of motor acceleration and time constants while the machining program is executed, without the need for trial executions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a fixed time constant is set based on maximum inertia ratio, then the machine tool can handle the heaviest workpiece, but the cycle time cannot be reduced when inertia is reduced due to cutting
Solution Approach 1:
The patent applies dynamics by making the time constant variable rather than fixed. The time constant is dynamically adjusted based on the current inertia ratio, which changes during machining as material is removed. This allows the system to optimize acceleration for the current workpiece weight while maintaining the ability to handle maximum inertia when needed.
Solution Approach 2:
The patent changes the parameter of time constant from a fixed value to a variable value that adapts to changing conditions. By monitoring the current inertia ratio and adjusting the time constant accordingly, the system achieves optimal cycle time for each machining stage while preserving the capability to handle the heaviest workpieces.
2Productivity
If the time constant is changed to reduce cycle time, then productivity improves, but vibration suppression and overload prevention become compromised
Solution Approach 1:
The patent implements feedback by continuously monitoring the current inertia ratio during machining and using this information to adjust the time constant. This closed-loop approach ensures that the time constant is optimized for productivity while automatically adapting to maintain vibration suppression and overload prevention by responding to actual machine state conditions.
3Productivity
If estimation of workpiece weight is performed before machining, then optimal time constant can be derived, but additional time is required for estimation and trial executions
Solution Approach 1:
The patent applies self-service by enabling the system to automatically estimate workpiece weight and derive optimal time constants during actual machining operations without requiring separate trial executions. The system uses real-time monitoring data to perform these functions autonomously, eliminating the need for additional setup time while maintaining optimal performance.
4Productivity
If acceleration is increased to reduce cycle time, then productivity improves, but the risk of motor overload and vibration increases
Solution Approach 1:
The patent uses dynamics to adjust acceleration levels based on current working conditions. By making acceleration a variable parameter that adapts to the current inertia ratio and machine state, the system can increase acceleration when conditions permit (reducing cycle time) while automatically reducing it when necessary to prevent overload and vibration, thus resolving the contradiction between productivity and harmful factors.
Data Source
AI summary
To dynamically change the acceleration without trial executions of a machining program, a numerical control device, which controls a motor on the basis of a machining program that specifies a path for a drive target of the motor, includes a changing unit that changes the acceleration of the motor under the control of the motor on the basis of the inertia ratio, the acceleration-deceleration factor that can be externally input, or the current value of the motor.