Casting Mold Nitrided Layer Repair via Molten Metal Pressurization

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Solution Overview

Problem

The existing methods for repairing nitrided layers on casting molds require offline re-nitriding treatments, leading to interruptions in the casting process and decreased productivity due to heat checking and nitrogen concentration depletion.

Innovation Solution

A nitrided layer repair method that involves applying a nitriding source, such as urea, to the mold cavity surface while pressurizing and solidifying molten metal, allowing for in-process nitriding and maintaining the nitrided layer without interrupting the casting process.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If offline re-nitriding treatment is performed to maintain nitrogen concentration and prevent heat checking, then the nitrided layer durability is improved, but the casting process is interrupted and productivity decreases

Engineering Contradiction:

Improvenitrided layer durabilityVSAvoidcasting process productivity

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

A nitriding source is applied to the mold cavity surface before the casting process begins, so that the nitrided layer is repaired in advance during mold preheating rather than requiring interruption later

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The nitriding treatment is performed continuously during the mold preheating phase without interrupting the casting production flow, maintaining both the nitrided layer and productivity

Inventive Principle:

Principle #20Continuity of useful action

2Reliability

If offline re-nitriding treatment is performed to restore nitrogen concentration on the mold surface, then heat checking is prevented, but time is lost due to process interruption

Engineering Contradiction:

Improveresistance to heat checkingVSAvoidprocess interruption time

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The nitriding source is applied during mold preheating before casting begins, performing the nitrogen restoration in advance so no time is lost during actual production

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The mold preheating process serves as an intermediary phase where nitriding can occur without affecting production, utilizing the preheating time for dual purposes

Inventive Principle:

Principle #24Intermediary (Mediator)

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 method effectively prevents the decrease in productivity by maintaining the nitrided layer's nitrogen concentration and hardness, thereby reducing heat checking and extending the mold's lifespan without interrupting the casting process.

Implementation Method 1

a molten metal is pressurized and solidified, and thus a nitrided layer formed on a surface of a casting mold

Methodology Applied

Scientific EffectPressurization: Pressurisation

Implementation Method 2

nitriding the cavity surface of the mold by heating and pressurizing the cavity surface using the molten metal

Methodology Applied

Scientific EffectHeating: Heating

Implementation Method 3

nitriding the cavity surface of the mold by heating and pressurizing the cavity surface using the molten metal

Methodology Applied

Scientific EffectNitriding: Nitriding

Implementation Method 4

a nitrided layer is formed on a surface of a casting mold

Methodology Applied

Scientific EffectDiffusion: Diffusion

Data Source

PatentUS10322446B2Nitrided layer repair method

Publication Date: 2019.06.18 TOYOTA JIDOSHA KK

AI summary

There is provided a nitrided layer repair method in which a molten metal is pressurized and solidified, and thus a nitrided layer formed on a cavity surface of a mold used to form a casting object is repaired. In the nitrided layer repair method, a nitriding source is applied to the cavity surface, and the cavity surface of the mold is nitrided by heating and pressurizing the cavity surface using the molten metal.