Inductive Heating of Closed Rings Using U-Shaped Core Air Gaps
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Solution Overview
Problem
Existing inductive heating technologies are inefficient for uniformly heating electrically conductive workpieces of different materials and dimensions, particularly those in the shape of closed rings, as they require specific inductors and can cause unwanted heating of conveyor devices due to magnetic field interference.
Innovation Solution
A U-shaped magnetic core with air gaps and coils arranged to form a closed magnetic circuit, allowing workpieces to be heated non-contactingly, using a low-frequency alternating current to induce electromotive force independently of workpiece dimensions, minimizing skin effect and magnetic reversal losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional inductive heating with U-shaped magnet core and coils is used, then heating of the workpiece can be achieved, but uniform heating of workpieces of different dimensions and materials cannot be achieved
Solution Approach 1:
The patent changes the fundamental parameters of the magnetic circuit by introducing a closed magnetic circuit configuration with controlled air gaps, replacing the conventional open U-shaped magnet core. This allows the magnetic flux to be confined and directed through the workpiece, creating uniform heating regardless of workpiece dimensions or material properties. The air gap distance is optimized to ensure consistent magnetic coupling across different workpiece types.
Solution Approach 2:
The closed magnetic circuit inductor design creates a universal heating system that can process workpieces of various dimensions and materials using the same apparatus. The magnetic circuit configuration ensures that the magnetic flux distributes uniformly through different workpiece geometries, making the system adaptable to diverse applications without requiring multiple specialized inductors.
2Productivity
If high frequency alternating current is used for inductive heating, then heating efficiency is improved, but skin effect and magnetic reversal losses increase
Solution Approach 1:
The patent optimizes the frequency parameter of the alternating current based on the specific workpiece characteristics and magnetic circuit configuration. By adjusting the frequency to match the resonant characteristics of the closed magnetic circuit, the system achieves efficient heating while minimizing skin effect and magnetic reversal losses. The closed magnetic circuit also improves magnetic flux containment, reducing energy dissipation.
3Temperature
If conventional inductive heating apparatus is used, then workpiece heating can be achieved, but unwanted heating of conveyor devices occurs due to magnetic field interference
Solution Approach 1:
The patent extracts and confines the magnetic field within a closed magnetic circuit, preventing magnetic flux from extending into the surrounding environment where it could interfere with conveyor devices. The magnetic circuit acts as a contained system, directing magnetic flux only through the intended workpiece while shielding adjacent equipment from harmful magnetic field effects.
Solution Approach 2:
The closed magnetic circuit with air gaps serves as an intermediary structure that mediates between the electromagnetic field and the workpiece, confining the magnetic field within defined boundaries. This intermediary configuration prevents direct interaction between the magnetic field and nearby conveyor devices, eliminating unwanted heating while maintaining effective workpiece heating.
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
Enables uniform heating of workpieces of varying sizes and materials without direct contact, reducing energy losses and minimizing heating of conveyor devices, thus improving the efficiency and versatility of the heating process.
Implementation Method 1
the coils (5) are supplied with an alternating current, that is connected to an alternating current source, so that in the workpiece (2) an electromotive force is induced
Implementation Method 2
Based on the principal of induction heating, it is known to create heat in an electrically conducting workpiece by means of an inductor
Implementation Method 3
The thinner the wall of a workpiece the greater must be the frequency of the alternating current source and with it the frequency of the created alternating magnetic field, so that the eddy currents created in the workpieces are close to a sufficiently large electrical resistance, so as to create sufficient heat by the eddy current losses
Data Source
AI summary
An apparatus for inductively heating an electrically conductive workpiece in the form of a closed ring includes a U-shaped magnet core with two legs, an electrically conducting coil arranged on at least one leg of the core and connectable with an alternating current source, and a magnet yoke spaced from at least one freestanding end of a leg of the core, so that a closed magnetic circuit with at least one air gap is formed, with the height of the air gap chosen such that the workpiece can be moved in a non-contacting manner into the air gap.