Induction Heating Fixture With Offset Coil for Uniform Bore Expansion
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Solution Overview
Problem
Achieving uniform temperature distribution in the bore of a bored part during induction heating is challenging, especially when the part is oriented horizontally, leading to potential misalignment during shrink-fitting due to uneven heating caused by convective heat transfer.
Innovation Solution
The method involves mounting an induction heating fixture with an eccentrically positioned induction heating coil inside the bore, closer to the lower surface than the upper surface, to induce a higher flux density in the lower portion and promote uniform temperature distribution, and using a fixture with a base and locators to secure the coil in place.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the induction heating coil is positioned coaxially with the bore axis, then the heating setup is simple and symmetric, but the temperature distribution in the bore becomes non-uniform due to convective heat transfer in horizontal orientation
Solution Approach 1:
The induction heating coil is deliberately positioned asymmetrically (eccentrically) within the bore, offset from the bore axis toward the lower surface. This asymmetric positioning compensates for convective heat transfer effects that cause non-uniform temperature distribution in horizontal orientations, thereby achieving uniform heating without requiring complex symmetric arrangements or part rotation
Solution Approach 2:
The heating coil is positioned at a specific location within the bore (closer to the lower surface) rather than being uniformly distributed. This localized positioning creates higher flux density in the lower portion of the bore, which compensates for heat loss due to convection and achieves uniform overall temperature distribution
2Use of energy by moving object
If the entire bored part is heated, then sufficient thermal energy is provided for shrink-fitting, but the heating time and energy consumption increase significantly
Solution Approach 1:
The heating coil is extracted from the conventional external positioning and placed inside the bore itself. This allows the heating energy to be concentrated directly in the region requiring thermal expansion, eliminating the need to heat the entire part and significantly reducing heating time and energy consumption
Solution Approach 2:
The heating process is segmented to focus only on the bore region rather than the entire part. The induction coil is positioned to heat specifically the bore area where thermal expansion is needed for shrink-fitting, leaving the rest of the part at lower temperature
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 ensures a more uniform heat distribution around the bore, reducing the risk of misalignment and facilitating a reliable interference fit between the bored part and a shaft without requiring the entire part to be heated or rotated.
Implementation Method 1
driving alternating electric current into the induction heating coil to heat the part
Implementation Method 2
heating a part having a bore formed therein using induction heating
Implementation Method 3
the induction heating coil is inductively coupled to the part
Implementation Method 4
the bored part is heated in order to thermally expand the size of the bore
Implementation Method 5
Subsequent cooling of the bored part with the shaft inserted in the bore causes the bore to contract and become engaged with the shaft via an interference fit
Data Source
AI summary
Fixtures and methods for induction heating of bored parts are described. The fixtures and methods may be used to counter the effects of convective heat transfer and thereby promote a more uniform temperature distribution around a bore of a bored part being heated. The fixture includes a base including one or more locators engaged with the part and locating the base relative to the part, and an induction heating coil supported by the base. The induction heating coil is disposed inside the bore of the part and is inductively coupled to the part. The induction heating coil is wound about a coil axis which is non-coaxial with a bore axis of the bore of the part during heating of the part.