Induction Heating of Ring Members for Uniform Bearing Expansion
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Solution Overview
Problem
Existing induction heating methods for ring-shaped members, such as those in bearings, face challenges in evenly heating components with varying radial thicknesses along the axial direction, leading to inefficiencies and increased manufacturing costs due to the need for customized coils and precise positional alignment.
Innovation Solution
The method involves using induction coils positioned either radially inward or outward of the ring-shaped member, with the effective length of the coils set to exceed the axial length of the member, allowing for independent heating steps to reach different target temperatures, ensuring even heating without the need for precise coil alignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If flame heating or induction heating is applied to the entire outer peripheral surface, then heating is comprehensive, but deformation occurs due to uneven heating between inner and outer surfaces
Solution Approach 1:
The heating process is segmented into multiple stages: first heating the inner peripheral surface, then heating the outer peripheral surface in specific regions (groove portions and portions between grooves) rather than uniformly across the entire outer surface. This segmented approach prevents uneven thermal expansion and deformation while ensuring comprehensive heating coverage.
Solution Approach 2:
The outer peripheral surface heating is applied locally to specific regions (groove portions and portions between grooves) rather than uniformly across the entire surface. This local quality approach ensures that critical areas receive adequate heating while avoiding excessive heat concentration that would cause deformation.
2Strength
If the ring-shaped member is heated and then cooled rapidly, then hardening is achieved, but cracks may occur due to thermal stress
Solution Approach 1:
The ring-shaped member is pre-heated to a specific temperature range (Ac3 point or higher) before quenching. This preliminary heating ensures uniform thermal state and proper austenite transformation, reducing thermal stress during subsequent rapid cooling and preventing crack formation while achieving the desired hardening effect.
3Productivity
If manual operation is used for heating and cooling processes, then flexibility is maintained, but productivity is low and quality is unstable
Solution Approach 1:
The manual mechanical heating and cooling operations are replaced with an automated induction heating system that uses electromagnetic fields to heat the ring-shaped member. The system includes automated conveyance mechanisms and control units that precisely control heating zones, temperature, and cooling rates, thereby improving both productivity and heating uniformity while maintaining stable quality.
4Strength
If the entire outer peripheral surface is heated, then hardening coverage is maximized, but distortion increases
Solution Approach 1:
Instead of heating the entire outer peripheral surface uniformly, the invention applies heating locally to specific regions (groove portions and portions between grooves) where hardening is most needed. This local quality approach achieves adequate hardening coverage while minimizing thermal stress and distortion that would result from heating the entire surface.
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 efficient and even heating of the entire ring-shaped member, reducing manufacturing costs and improving productivity by allowing for the use of standardized coils across various ring shapes and sizes.
Implementation Method 1
a method for inductively heating a ring-shaped member
Implementation Method 2
Heating is performed by causing eddy currents to flow
Data Source
Figure 1
Figure 2
Figure 3~3(B)
AI summary
A ring-shaped member is induction-heated by supplying a current to an induction coil. An induction heating step includes induction-heating the ring-shaped member using an induction coil (17) disposed at a radially inward position of the ring-shaped member in a state in which no substantial coil is disposed at a radially outward position of the ring-shaped member, or induction-heating the ring-shaped member using an induction coil (18) disposed at the radially outward position of the ring-shaped member in a state in which no substantial coil is disposed at the radially inward position of the ring-shaped member. Effective lengths of the induction coils (17, 18) are set to be larger than an axial length of the ring-shaped member.