Inductor Two-Loop Design for Rack Gear Hardening

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Solution Overview

Problem

Existing inductive hardening methods for toothed racks lack optimal control over the hardening pattern and efficiency, particularly in achieving uniform hardness and minimizing equipment requirements.

Innovation Solution

An inductor with an annular induction coil having two loops that encompass the workpiece, allowing for relative movement to generate eddy currents perpendicular to the tooth flanks, with a field guide and connector design to enhance the magnetic field and hardness profile.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If a single-loop annular induction coil is used for feed hardening, then the equipment complexity is reduced and power requirements are lowered, but the hardening pattern control is insufficient and uniformity is poor

Engineering Contradiction:
Improvehardening pattern uniformityVSAvoidinductor structure
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The induction coil is divided into two separate loops instead of using a single loop. Each loop independently encloses the workpiece and generates eddy currents, allowing separate control of hardening zones. This segmentation enables precise control over the hardening pattern while maintaining relatively simple inductor structure.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Each loop is positioned to target specific regions of the workpiece, creating localized eddy currents in different zones. The first loop generates eddy currents in one region while the second loop targets another region, allowing different hardening characteristics in different areas of the workpiece surface.

Inventive Principle:
Principle #3Local quality

2Productivity

If high power is used for simultaneous hardening over the entire length, then productivity is improved, but the equipment requirements and power consumption increase significantly

Engineering Contradiction:
Improvehardening speedVSAvoidpower requirement
Core Design Contradiction:
ProductivityVSPower

Solution Approach 1:

The inductor moves continuously along the workpiece in a feed hardening process, applying periodic heating action along the length of the workpiece. This allows progressive hardening without requiring high power for simultaneous heating of the entire workpiece, maintaining productivity while reducing peak power requirements.

Inventive Principle:
Principle #19Periodic action

Solution Approach 2:

Instead of heating the entire workpiece length simultaneously with excessive power, the two-loop configuration applies partial heating action to specific zones at different times as the inductor moves along the workpiece, achieving complete hardening through cumulative effect with lower power requirements.

Inventive Principle:
Principle #16Partial or excessive action

3Power

If the inductor is moved relative to the workpiece for gradual heating, then power requirements are reduced and hardening pattern control is improved, but the processing time increases

Engineering Contradiction:
Improvepower requirementVSAvoidprocessing time
Core Design Contradiction:
PowerVSLoss of time

Solution Approach 1:

The feed hardening process maintains continuous relative motion between the inductor and workpiece, ensuring uninterrupted heating action. The two-loop configuration ensures that useful heating action is continuously applied as the inductor moves along the workpiece, reducing total processing time compared to intermittent or stepped heating methods.

Inventive Principle:
Principle #20Continuity of useful action

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 design enables improved control over the hardening pattern, achieving uniform hardness and reducing power requirements while preventing unwanted flashovers, resulting in a more efficient and effective hardening process.

Implementation Method 1

The inductor generates an eddy current locally in the workpiece via induction, so that it is successively heated.

Methodology Applied
Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 2

The inductor generates an eddy current locally in the workpiece via induction

Methodology Applied
Scientific EffectEddy current: Eddy Currents

Implementation Method 3

the induction coil is essentially made of copper and is preferably a tube so that water or another liquid can be passed through the induction coil to cool the inductor

Methodology Applied
Scientific EffectThermal conduction: Conduction (thermal)

Data Source

PatentEP3724360B1Inductor and method for hardening rack gears
Publication Date: 2023.09.06 IDEA GMBH
  • EP3724360B1 patent drawingFigure 1
  • EP3724360B1 patent drawingFigure 2~3
  • EP3724360B1 patent drawingFigure 4~5

AI summary

The invention relates to an inductor (1) for the progressive induction hardening of rack gears and to the hardening process using said inductor (1). The inductor (1) has an annular induction coil (2) for surrounding the rack gear in the receiving chamber (8) for the rack gear. In order to improve the hardening pattern, two loops (7) of the induction coil (2) surround the receiving chamber (8), each loop covering half of the circumference of the receiving chamber (8).