Eccentric Induction Coil Fixture for Uniform Bore Heating
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Solution Overview
Problem
Achieving uniform temperature distribution in the bore of a bored part during induction heating is challenging, particularly when using shrink-fitting techniques, as conventional methods often result in uneven heating due to convective heat transfer, which can lead to misalignment issues during interference fit establishment.
Innovation Solution
The method involves orienting the bored part so that its bore axis is between 0 and 45 degrees horizontal and positioning an induction heating coil eccentrically within the bore, closer to the lower surface than the upper surface, to induce a higher flux density and promote uniform temperature distribution, using an adjustable fixture to ensure optimal coupling distances and alignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If conventional induction heating is used on bored parts, then heating can be achieved, but uniform temperature distribution in the bore region is difficult to obtain due to convective heat transfer
Solution Approach 1:
The induction heating coil is positioned asymmetrically within the bore, specifically closer to the lower surface than the upper surface. This asymmetric positioning creates a non-uniform magnetic flux distribution that compensates for convective heat transfer effects, thereby achieving more uniform temperature distribution throughout the bore region
Solution Approach 2:
The coil axis is deliberately offset from the bore axis, creating a non-coaxial arrangement. This dimensional offset introduces a new spatial relationship between the heating source and the workpiece, allowing the magnetic flux to penetrate the bore wall more effectively at specific locations and achieve uniform heating despite gravitational convection
2Temperature
If the entire bored part is heated prior to shrink-fitting, then sufficient thermal expansion can be achieved, but heating time and energy consumption increase
Solution Approach 1:
The induction heating coil is positioned to concentrate heating energy specifically in the bore region where thermal expansion is most needed for shrink-fitting. By localizing the heating action to the critical area rather than heating the entire part, the process achieves sufficient thermal expansion at the bore while significantly reducing overall heating time and energy consumption
3Ease of manufacture
If the induction heating coil is positioned coaxially with the bore, then alignment is simple, but uniform heating is compromised due to convective heat transfer effects
Solution Approach 1:
The coil is intentionally positioned asymmetrically relative to the bore axis, with the coil axis offset from the bore axis. This asymmetric positioning may require slightly more complex alignment procedures compared to coaxial positioning, but it directly addresses the heating uniformity problem by creating a magnetic flux distribution that compensates for convective heat transfer
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 facilitates a more uniform heat distribution around the bore, reducing the risk of misalignment and enhancing the effectiveness of the shrink-fitting process by compensating for convective heat transfer, thereby ensuring a reliable interference fit without the need for rotating the part.
Implementation Method 1
driving alternating electric current into the induction heating coil to heat the part
Implementation Method 2
the induction heating coil is inductively coupled to the part
Implementation Method 3
the bored part is heated in order to thermally expand the size of the bore
Implementation Method 4
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
Figure 1
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AI summary
Fixtures and methods for induction heating of bored parts may be used to counter the effects of convective heat transfer and thereby promote a more uniform temperature distribution around a bore (14) of a bored part (12) being heated. The fixture (10) includes a base (16) including one or more locators engaged with the part (12) and locating the base (16) relative to the part (12), and an induction heating coil (18) supported by the base (16). The induction heating coil (18) is disposed inside the bore (14) of the part (12) and is inductively coupled to the part (12). The induction heating coil (18) is wound about a coil axis (CA) which is non-coaxial with a bore axis (BA) of the bore (14) of the part (12) during heating of the part (12).