Transformerless Induction Heating Head With Stacked Spiral Coil
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Solution Overview
Problem
Existing induction heating systems for preheating thick steel prior to welding face challenges with moving workpieces, require impedance matching transformers, and lack consistent coil-to-heat zone distance, temperature feedback, and expandability, especially for smaller diameter pipes.
Innovation Solution
An induction heating head with a conductive coil wound in a pancake spiral pattern, tuned to the power source, and equipped with a flux concentrator, spacers, and temperature sensors, allowing direct connection to the power source without transformers, maintaining consistent heat zone distance and providing temperature feedback.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a matching transformer is used between the power source and induction head, then impedance matching is achieved, but the applied voltage to the coil is reduced and equipment complexity increases
Solution Approach 1:
The patent removes the matching transformer from the system entirely. The induction head is designed with a coil whose impedance is inherently matched to the power source output, eliminating the need for an external matching transformer. This extraction of the transformer component resolves the contradiction by achieving impedance matching through design rather than transformation, thereby maintaining full applied voltage to the coil.
Solution Approach 2:
The patent changes the impedance parameter of the induction coil itself to match the power source output. By designing the coil with specific inductance and resistance characteristics that inherently match the power source, the system achieves impedance matching without requiring voltage transformation. This parameter change approach eliminates the voltage reduction associated with transformer usage.
2Reliability
If a matching transformer is used between the power source and induction head, then impedance matching is achieved, but device complexity and cost increase
Solution Approach 1:
The patent extracts and removes the matching transformer component from the system. The induction head is designed with a coil whose impedance is inherently matched to the power source, eliminating the need for additional matching equipment. This reduction in components directly decreases device complexity and associated costs while maintaining reliable impedance matching.
3Productivity
If the coil-to-heat zone distance is not maintained consistently, then heating efficiency varies, but maintaining distance requires additional positioning mechanisms
Solution Approach 1:
The patent creates a magnetic flux concentration zone that acts as a virtual positioning reference. The flux concentrator geometry is designed so that the magnetic flux naturally concentrates at a specific distance from the coil face, creating an equipotential heating zone. This eliminates the need for mechanical positioning mechanisms because the heating efficiency is maintained by the magnetic field distribution rather than physical distance control.
4Manufacturing precision
If temperature feedback is not implemented, then temperature control is lacking, but adding sensors and control systems increases device complexity
Solution Approach 1:
The patent implements temperature feedback using temperature sensors that monitor the workpiece temperature and provide signals to the power source controller. The controller adjusts the power output based on the temperature feedback to maintain the desired temperature range. This feedback mechanism achieves precise temperature control while integrating seamlessly with the existing system architecture.
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 efficient preheating of moving workpieces without transformers, ensuring consistent heating, accommodating various diameters, and offering temperature control, thus improving welding efficiency and reducing equipment wear.
Implementation Method 1
induction heating head includes a conductive coil... The conductive coil induces heat in a workpiece
Implementation Method 2
inducing current in the workpiece
Implementation Method 3
a flux concentrator disposed about the conductive coil that concentrates flux toward the first face
Data Source
AI summary
An induction heating system includes a power source and an induction head. The converter output is at a voltage that is not greater than the voltage applied to the coil. The induction head includes a housing that houses a conductive coil disposed to induce heat in a workpiece and the coil is wound to be tuned to the output power. The coil is wound in a stacked spiral pattern with at least two turns in each layer. A flux concentrator is disposed about the coil with a potting compound around the concentrator and coil. Spacers maintain a desired separation between the head and the workpiece. The coil is a tube carrying a coolant. The head includes a wear surface that prevents contact of the coil and the workpiece, and a thermal insulator between the coil and wear surface. A non-contact temperature sensor is mounted to the housing.