Inductor Segmentation for Uniform Hardness in Crankshaft Heat Treatment
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Solution Overview
Problem
Existing methods for induction heat treatment of complex-shaped metal workpieces, such as crankshafts, often result in undesirable 'thumbnail' heating patterns that waste energy and cause shape distortion due to uneven heat distribution across the transverse width and fillet regions, leading to increased hardness depth and volumetric expansion.
Innovation Solution
An inductor assembly with inter-lips and cross-lips magnetic flux concentrators, along with independently variable electrical current parameters, is used to control the metallurgical hardness pattern across the transverse width of cylindrical components, reducing electromagnetic coupling and thermal heat sinks to achieve uniform heat treatment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If conventional induction heat treatment is applied to complex-shaped workpieces, then the workpiece can be heated, but undesirable 'thumbnail' heating patterns occur causing uneven heat distribution and shape distortion
Solution Approach 1:
The inductor is divided into multiple independently controllable coil segments (first inductor segment, second inductor segment, third inductor segment) that can be individually activated or deactivated. This segmentation allows selective heating of different regions (transverse width vs. fillet regions) to achieve uniform heat distribution and prevent thumbnail patterns that cause shape distortion
Solution Approach 2:
Different regions of the workpiece receive different heating treatments through localized control of coil segments. The first and second inductor segments heat the transverse width region while the third inductor segment heats the fillet regions, creating locally optimized heat distribution that eliminates uniform thumbnail patterns across the entire workpiece
2Temperature
If conventional induction heat treatment is applied to complex-shaped workpieces, then the workpiece can be heated, but energy is wasted due to uneven heat distribution and thermal heat sinks
Solution Approach 1:
The inductor is divided into multiple independently controllable coil segments (first inductor segment, second inductor segment, third inductor segment) that can be individually activated or deactivated. This segmentation allows selective heating of different regions (transverse width vs. fillet regions) to achieve uniform heat distribution and prevent thumbnail patterns that cause shape distortion
Solution Approach 2:
Different regions of the workpiece receive different heating treatments through localized control of coil segments. The first and second inductor segments heat the transverse width region while the third inductor segment heats the fillet regions, creating locally optimized heat distribution that eliminates uniform thumbnail patterns across the entire workpiece
3Manufacturing precision
If conventional induction heat treatment is applied to complex-shaped workpieces, then the workpiece can be heated, but hardness distribution is uneven across the transverse width and fillet regions
Solution Approach 1:
The inductor is divided into multiple independently controllable coil segments (first inductor segment, second inductor segment, third inductor segment) that can be individually activated or deactivated. This segmentation allows selective heating of different regions (transverse width vs. fillet regions) to achieve uniform heat distribution and prevent thumbnail patterns that cause shape distortion
Solution Approach 2:
Different regions of the workpiece receive different heating treatments through localized control of coil segments. The first and second inductor segments heat the transverse width region while the third inductor segment heats the fillet regions, creating locally optimized heat distribution that eliminates uniform thumbnail patterns across the entire workpiece
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 enables precise control of the heat treatment process, reducing energy waste and shape distortion by ensuring uniform hardness distribution and minimizing the 'thumbnail' heating pattern, thus improving the efficiency and accuracy of induction hardening.
Implementation Method 1
When the bottom and top inductor segments are in the closed position and alternating current is supplied to bottom segment inductor (107), magnetic flux concentrators, for example concentrators (103 a) and (103b) in patent figure 2(c), are used to magnetically couple the flux created around the bottom inductor segment caused by current flow in the bottom (active) inductor segment so that a current flow having an instantaneous direction opposite to that in the bottom segment inductor is induced in the top (passive) inductor segment.
Implementation Method 2
U.S. Patent No. 6,274,857(the 857 patent) discloses a method of, and apparatus for, induction heat treatment of irregularly shaped workpieces such as selected components of a crankshaft.
Implementation Method 3
magnetic flux concentrators, for example concentrators (103 a) and (103b) in patent figure 2(c), are used to magnetically couple the flux created around the bottom inductor segment
Implementation Method 4
In the closed position, dielectric material (410) separates the opposing facing surfaces of the bottom and top inductor segments as shown in patent figure 2(c).
Implementation Method 5
One or more side shields (137), as illustrated in patent figure 5(a) can be provided on one, or both, inner and outer sides of a coil segment around the arcuate coil region formed around a coil lip to serve as a magnetic flux concentrator for the workpiece component being heat-treated, and as a magnetic field shield for the workpiece components adjoining the heat-treated component.
Data Source
Figure 1(a)~1(b)
Figure 2(a)~2(b)
Figure 3(a)~3(b)
AI summary
Apparatus and method are provided for induction heating of one or more components of a complex shaped workpiece. The component is positioned within an opening formed by opposing pairs of arcuate coil structures formed in opposing inductor segments. One inductor segment is formed from electrically isolated inner and outer active inductor segments connected to one or more power supplies while the other inductor segment is formed from electrically isolated inner and outer passive inductor segments that are magnetically coupled with respective inner and outer active inductor segments. Changing the output electrical parameters of the one or more power supplies controls the induction hardening along the transverse width of the workpiece with optional flux concentrators between opposing pairs of arcuate coil structures.