Numerical Controller Spindle Overheat Prediction and Safe Stop
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Solution Overview
Problem
Conventional numerical controllers cannot accurately determine the block at which to stop machining operations to avoid overheating alarms, leading to potential damage of machined surfaces when the spindle motor's continuous rated output is exceeded.
Innovation Solution
A numerical controller that predicts execution times of command blocks, identifies an alarm generation block, and automatically stops the operation at a non-cutting block to prevent overheating, using a machining continuable time estimation unit, program operation unit, machining time prediction unit, alarm generation block identification unit, and stop block identification unit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the operation is stopped in the middle of cutting due to overheat alarm, then the motor overheating is prevented, but the machined surface may be damaged and machining quality deteriorates
Solution Approach 1:
The system performs preliminary analysis of the machining program to predict future overheating risks and identifies appropriate stop blocks in advance. By analyzing command blocks ahead of time and calculating machining continuable times, the system prepares a safe stop plan before overheating occurs, allowing the operation to be interrupted at an appropriate non-cutting block rather than in the middle of cutting.
Solution Approach 2:
The system dynamically adjusts the stop decision based on real-time motor temperature, current load, and predicted machining continuable time. The stop block identification unit selects the most appropriate block to stop at by considering the current machining state and predicted future states, making the stop timing adaptive rather than fixed.
2Reliability
If the operator manually determines whether the program can be performed to the last within machining continuable time, then the operation can be stopped before overheat alarm, but it is difficult to identify the appropriate block to stop at
Solution Approach 1:
The system performs automatic block identification and stop decision-making without requiring manual operator analysis. The alarm generation block identification unit and stop block identification unit automatically analyze the machining program, predict overheating risks, and identify the appropriate stop block, eliminating the burden of manual determination from the operator.
Solution Approach 2:
The system provides feedback to the operator by displaying the identified stop block and machining continuable time information. This feedback mechanism allows the operator to verify the system's analysis and understand why a particular block was selected, making the automatic identification process transparent and trustworthy.
3Productivity
If the machining continuable time is extended to complete the entire program, then productivity increases, but the motor may overheat and cause damage
Solution Approach 1:
The system performs preliminary calculation of machining continuable time based on motor temperature, current load, and program analysis before executing the machining operation. By knowing the predicted overheating risk in advance, the system can plan the machining process to complete as much as possible within the safe time window, maximizing productivity while ensuring motor safety.
Solution Approach 2:
The system dynamically determines the machining continuable time based on real-time motor conditions and program characteristics. Rather than using a fixed time limit, the system adjusts the continuable time based on actual motor temperature, load variations, and the specific machining operations remaining, allowing optimal utilization of the motor's thermal capacity.
Data Source
AI summary
A numerical controller estimates a machining continuable time before a currently controlled motor overheats if an output of the motor exceeds a continuous rated output and predicts respective execution times of command blocks and the machining continuable time for each command block, for a currently running block and its subsequent command blocks. Based on these predicted data, the numerical controller identifies a command block (alarm generation block) in which the motor overheats and a command block (stop block) in which driving control can be safely stopped, within the range of command blocks from the currently running command block to the alarm generation block.