Surface Treatment Method for Steel Objects

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Solution Overview

Problem

Existing surface treatment methods for steel objects face challenges in uniformly heating complex shapes, leading to inefficient surface treatments due to non-uniform heating and potential decomposition or reaction of processing gases before they reach the surface.

Innovation Solution

A surface treatment method and device where the atmosphere around the steel object is heated to uniformly heat its surface, followed by direct heating with a processing gas like ammonia to prevent decomposition and ensure uniform solid-solutionization of elements, using a device with a light-transmitting wall to prevent gas reaction and a transfer unit for vacuum transfer to maintain surface temperature.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If the processing object is directly heated by inductive heating, laser emission heating, or infrared radiation heating, then the surface treatment can be performed, but it is difficult to uniformly heat the processing object especially when it has a complicated shape

Engineering Contradiction:
Improvesurface temperature uniformityVSAvoidheating method complexity
Core Design Contradiction:
TemperatureVSDevice complexity

Solution Approach 1:

The patent introduces an atmosphere heating unit that heats the atmospheric gas surrounding the processing object as an intermediary medium. This indirect heating approach allows uniform heat distribution to the entire surface of complex-shaped objects without requiring direct contact or line-of-sight heating, resolving the contradiction between achieving uniform surface temperature and avoiding complex heating device configurations.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Temperature

If the atmosphere is heated to uniformly heat the processing object, then uniform heating is achieved, but the processing gas may decompose or react before reaching the surface

Engineering Contradiction:
Improvesurface temperature uniformityVSAvoidprocessing gas stability
Core Design Contradiction:
TemperatureVSReliability

Solution Approach 1:

The patent performs preliminary heating of the processing object in the atmosphere heating unit before introducing the processing gas. This preliminary action ensures the object reaches the required temperature for surface treatment, allowing the subsequent processing gas to be applied at lower temperatures where decomposition and unwanted reactions are minimized, thus maintaining gas stability while achieving uniform heating.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent divides the treatment process into two distinct stages: first heating the atmosphere and object separately in the atmosphere heating unit, then introducing processing gas in the surface treatment unit. This segmentation allows independent optimization of heating and gas treatment, preventing gas decomposition while achieving uniform surface temperature.

Inventive Principle:
Principle #1Segmentation

3Adaptability or versatility

If the processing object is transferred between separate carburizing and nitriding chambers, then comprehensive surface treatment is achieved, but the treatment time increases

Engineering Contradiction:
Improvetreatment type coverageVSAvoidtotal treatment time
Core Design Contradiction:
Adaptability or versatilityVSLoss of time

Solution Approach 1:

The patent combines multiple surface treatment functions (carburizing, nitriding, and atmosphere heating) into a single integrated processing chamber. This allows sequential or simultaneous application of different treatments without transferring the object between chambers, significantly reducing treatment time while maintaining comprehensive surface treatment capabilities through the versatile gas supply system.

Inventive Principle:
Principle #5Merging (Combining)

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 allows for efficient and uniform surface treatment of steel objects, even those with complex shapes, by maintaining a consistent surface temperature and preventing gas decomposition, thereby enhancing the quality and consistency of treatments like nitriding and carburizing.

Implementation Method 1

a first heating unit configured to heat an atmosphere around the processing object P with a light-transmitting wall 34

Methodology Applied
Scientific EffectThermal radiation: Thermal Radiation

Implementation Method 2

when an atmosphere around the processing object is heated, it is possible to uniformly heat the surface of the processing object

Methodology Applied
Scientific EffectConvection: Convection

Implementation Method 3

a second heating unit configured to emit light to the processing object P in the interior of the processing chamber 31 and thereby directly heat the processing object P

Methodology Applied
Scientific EffectInfrared radiation: Infrared Radiation

Implementation Method 4

a first wall 341 facing an outside of the processing chamber 31 and a second wall 342 facing an inside of the processing chamber 31

Methodology Applied
Scientific EffectLight absorption: Absorption (EM radiation)

Implementation Method 5

a light-transmitting wall 34 having light transmittance

Methodology Applied
Scientific EffectLight transmission: Light

Implementation Method 6

a space S is formed between the first wall 341 and the second wall 342

Methodology Applied
Scientific EffectThermal insulation: Thermal Insulation

Implementation Method 7

the processing object P is transferred from the heating chamber 21 to the processing chamber 31 under a reduced pressure atmosphere close to a vacuum

Methodology Applied
Scientific EffectVacuum: Vacuum

Implementation Method 8

a suction pump 43 configured to remove air in the passage 41

Methodology Applied
Scientific EffectPressure gradient: Pressure Gradient

Data Source

PatentEP3260571B1Surface treatment method and surface treatment device
Publication Date: 2023.07.12 TOYOTA JIDOSHA KK
  • EP3260571B1 patent drawingFigure 1
  • EP3260571B1 patent drawingFigure 2
  • EP3260571B1 patent drawingFigure 3

AI summary

There is provided a surface treatment method in which a processing gas (G2) is brought in contact with a heated processing object made of steel (P), an element in the processing gas (G2) is solid-solutionized, and thus a surface treatment is performed on the processing object (P). The processing object (P) is heated to a heating temperature (T1) in a vicinity of a processing temperature (T3) at which the surface treatment is performed by heating an atmosphere in which the processing object (P) is disposed. The surface treatment is performed by bringing the processing gas in contact with a surface of the processing object (P) while the processing object (P) which is heated is directly heated to the processing temperature (T3).