Tubular Preform Resistive Heating Mandrel
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Solution Overview
Problem
Existing heat treatment systems for tubular preforms face issues such as mandrel deflection, safety concerns, and inefficiencies due to the use of hot fluid mediums or induction heating, which result in shape distortion and poor product quality.
Innovation Solution
A resistive heating system using a longitudinally oriented outer and inner electrical conductor with a rotational support structure, where the preform is loaded on the outer conductor and heated through series electrical resistance, minimizing external electromagnetic fields and enhancing safety and efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a hot fluid medium is circulated through the tubular mandrel for heat curing, then the preform can be heated and cured, but the mandrel experiences appreciable deflection resulting in shape distortion
Solution Approach 1:
The patent replaces the mechanical/thermal convection system (hot fluid circulation) with an electromagnetic heating system. Electrical conductors embedded in or on the mandrel generate heat through resistive heating when electrical current passes through them, eliminating the need for fluid circulation and the associated thermal gradients that cause mandrel deflection and shape distortion.
2Temperature
If a large volume of hot fluid medium is circulated through the tubular mandrel, then heat treatment can be maintained, but safety concerns and maintenance issues arise
Solution Approach 1:
The patent eliminates the hot fluid circulation system entirely by using electrical resistive heating through conductors. This substitution removes safety hazards associated with high-temperature fluid handling, leakage risks, and complex maintenance requirements while maintaining effective heat treatment capability.
3Temperature
If an induction coil is used to heat the mandrel, then heat treatment can be applied, but axial deflection requires an appreciable coil surface to mandrel surface gap that negatively affects electrical efficiency
Solution Approach 1:
The patent embeds electrical conductors directly within or on the surface of the mandrel structure itself. This nested arrangement eliminates the need for external induction coils and the problematic air gaps between coils and mandrel, ensuring direct energy transfer and high electrical efficiency while maintaining uniform heat distribution.
4Manufacturing precision
If the mandrel is rotated to compensate for gravity effects, then consistent wall thickness can be achieved, but the heating system becomes more complex
Solution Approach 1:
The patent integrates the heating function directly into the mandrel structure through embedded conductors, making the mandrel itself the heating element. This eliminates the need for separate external heating systems, rotation mechanisms for heat distribution, and associated complexity, while still achieving uniform heating and consistent wall thickness through the inherent symmetry of the embedded conductor arrangement.
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 method allows for uniform and efficient heat treatment of tubular preforms, reducing shape distortion and improving product quality while minimizing safety risks and electromagnetic interference.
Implementation Method 1
The first adjacent ends of the outer and inner longitudinally oriented first and second electrical conductors are suitably connected together to form a series electrical resistance
Data Source
AI summary
Apparatus and method are provided for heat treatment of a tubular preform material that is loaded onto the outer surface of an electrically conductive mandrel forming a rotatable tubular shaped resistance heater.