Numerical Controller for Induction Motor Heat Suppression
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Solution Overview
Problem
Induction motors in machine tools face heat generation and instability during deep cutting operations due to abrupt load variations, leading to decreased spindle speed or shutdowns, as existing techniques do not effectively manage magnetic flux and torque.
Innovation Solution
A numerical controller that acquires and adjusts the magnetic flux amount of the spindle motor, changing the feed axis driving motor speed based on the magnetic flux ratio to maintain stable cutting operations by adjusting the feed rate accordingly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If magnetic flux or excitation current is weakened when load is light, then heat generation is suppressed, but spindle speed decreases greatly or spindle stops when deep cutting operation starts
Solution Approach 1:
The patent applies dynamics by making the magnetic flux amount adjustable and variable based on operational conditions. The control device dynamically changes the magnetic flux amount of the induction motor according to the operating state (light load vs. deep cutting operation), allowing the system to adapt between suppressing heat generation during light loads and maintaining torque for stable spindle speed during heavy loads.
Solution Approach 2:
The patent changes the magnetic flux amount parameter of the induction motor based on detected operating conditions. By adjusting this physical parameter according to whether the machine is in light load or deep cutting mode, the system optimizes both heat generation suppression and spindle speed stability without requiring a fixed magnetic flux setting.
2Power
If excitation current flows into stator coil to generate rotating magnetic field, then electromagnetic force is generated for rotor rotation, but heat is generated in the process
Solution Approach 1:
The patent applies partial action by providing only the necessary amount of excitation current required for the current load condition. Instead of maintaining full excitation current continuously, the control device adjusts the magnetic flux amount to match the actual demand, using partial excitation during light loads to reduce heat generation while maintaining sufficient electromagnetic force when needed.
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 approach effectively suppresses heat generation and ensures stable cutting operations during deep cutting by dynamically managing the magnetic flux and torque, preventing spindle speed decreases and shutdowns.
Implementation Method 1
an induction motor is a motor that causes an excitation current to flow into a stator coil to generate a rotating magnetic field and generate an induction current in a rotor so that the rotor rotates with the electromagnetic force
Implementation Method 2
the rotor rotates with the electromagnetic force so as to follow the rotation of the rotating magnetic field
Implementation Method 3
the magnetic flux amount acquisition means may estimate a present magnetic flux amount of the spindle motor and acquire the estimated magnetic flux amount as the present magnetic flux amount
Data Source
AI summary
A controller of a machine tool capable of suppressing heat generation and realizing a stable cutting operation during deep cutting is provided. A numerical controller for controlling a machine tool including a spindle motor formed of an induction motor and a feed axis driving motor includes: a magnetic flux amount acquisition means that acquires a present magnetic flux amount of the spindle motor; and a speed change means that changes a speed of the feed axis driving motor on the basis of the magnetic flux amount.