Numerical Controller Magnetic Flux Adjustment for Machine Tool Heat and Speed
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Solution Overview
Problem
Induction motors in machine tools face heat generation issues and reduced spindle speed or stopping during heavy cutting due to weakened magnetic flux, leading to inefficient cutting processes.
Innovation Solution
A numerical controller that acquires and adjusts the magnetic flux content of the spindle motor, changing the feed speed of the feed axis drive motor based on the magnetic flux content and elapsed time to maintain stable operation and reduce heat generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If magnetic flux is weakened to reduce heat generation in the induction motor, then heat generation is reduced, but the spindle speed reduces or stops during heavy cutting
Solution Approach 1:
The patent dynamically adjusts the magnetic flux content based on the cutting state. During light cutting, magnetic flux is weakened to reduce heat generation. During heavy cutting, magnetic flux is strengthened to maintain sufficient torque and prevent spindle speed reduction or stopping. This dynamic adjustment resolves the contradiction between heat reduction and speed maintenance.
Solution Approach 2:
The patent changes the magnetic flux content parameter according to cutting conditions. By controlling the excitation current to adjust magnetic flux content, the system optimizes the balance between heat generation and torque output, allowing the spindle to maintain appropriate speed during heavy cutting while reducing heat during light cutting.
2Temperature
If magnetic flux is weakened to reduce heat generation, then heat generation is reduced, but cutting efficiency decreases during light cutting
Solution Approach 1:
The system dynamically adjusts magnetic flux content based on detected cutting state. During light cutting operations, the magnetic flux is optimized to maintain efficient cutting while still providing some heat reduction. The control unit continuously monitors cutting conditions and adjusts magnetic flux accordingly, preventing excessive heat generation while maintaining cutting efficiency.
3Temperature
If feed speed is maintained at low speed to reduce heat generation, then heat generation is reduced, but cutting efficiency is reduced
Solution Approach 1:
The patent implements dynamic control of both magnetic flux content and feed speed based on cutting state. During heavy cutting, feed speed is reduced and magnetic flux is strengthened to maintain torque. During light cutting, feed speed is increased and magnetic flux is optimized to balance heat generation and cutting efficiency. This coordinated dynamic control resolves the contradiction between heat reduction and productivity.
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
The solution enables stable heavy cutting and efficient light cutting by reducing heat generation and preventing spindle speed reduction or stopping, while optimizing feed speed adjustments.
Implementation Method 1
an induction motor has been used as the spindle motor of a machine tool. The induction motor mentioned herein is a motor in which an excitation current is caused to flow in a stator coil to generate a rotating magnetic field, while an induction current is generated in a rotor and resultant magnetic force is used for rotating the rotor
Implementation Method 2
The induction motor has had a drawback that the flow of the excitation current in the stator coil generates heat
Data Source
AI summary
To provide a numerical controller for a machine tool capable of reducing heat generation and realizing stable heavy cutting, and also capable of realizing efficient light cutting. A numerical controller comprises: first speed change means which changes the feed speed of a feed axis drive motor at the start of cutting to an initial speed lower than a command speed, based on magnetic flux content at the start of cutting; and second speed change means which changes the feed speed from the initial speed to the command speed continuously or intermittently based on time elapsed from the start of cutting and a time constant for change in the magnetic flux content.