Thermal Cleaning of Workpieces in Hot Forging

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Solution Overview

Problem

In hot or semi-hot forging processes, contaminants from pretreatment residues and dust can lead to thermal decomposition, reducing the quality of the finished product and causing material embrittlement due to hydrogen absorption, while mechanical cleaning is incomplete and may affect coated parts, and inadequate corrosion protection is ensured.

Innovation Solution

A method involving a cleaning step before heating the workpiece to remove pretreatment residues, where the workpiece is thermally treated to a cleaning temperature using a burner, preferably on both sides, and then transported to a heating station to reach the target temperature, ensuring effective removal of contaminants and minimizing energy consumption.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-generated harmful factors

If mechanical cleaning (e.g., shot blasting) is used to remove residues, then some contaminants are removed, but it cannot completely remove residues and may affect coated semi-finished products

Engineering Contradiction:
Improveresidue contaminationVSAvoidcoating integrity
Core Design Contradiction:
Object-generated harmful factorsVSReliability

Solution Approach 1:

The patent replaces mechanical cleaning methods (shot blasting) with thermal cleaning using a burner. The burner heats the workpiece surface to a cleaning temperature that decomposes and removes organic residues without mechanical contact, thus preserving the coating integrity while effectively eliminating contaminants.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the cleaning parameter from mechanical force to thermal energy. By controlling the heating temperature to a specific cleaning temperature range, the method achieves effective residue removal through thermal decomposition while maintaining the integrity of protective coatings that would be damaged by mechanical cleaning.

Inventive Principle:
Principle #35Parameter changes

2Reliability

If anti-corrosion oil or lubricants are applied to prevent corrosion, then corrosion protection is improved, but thermal decomposition during heating creates pollutants and hydrogen absorption leading to embrittlement

Engineering Contradiction:
Improvecorrosion protectionVSAvoidpollutants and hydrogen embrittlement
Core Design Contradiction:
ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The patent applies preliminary thermal cleaning before the main heating process. By removing residues through thermal decomposition at cleaning temperature prior to forming heating, the method prevents the formation of pollutants and hydrogen embrittlement while maintaining corrosion protection benefits from the applied oils or lubricants.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent introduces a dedicated thermal cleaning step that rapidly removes residues through controlled heating and subsequent extraction. This quick thermal treatment skips the problematic phase where residues would decompose during prolonged heating, thereby preventing pollutant formation and hydrogen absorption.

Inventive Principle:
Principle #21Skipping (Rushing through)

3Productivity

If the workpiece is heated directly without cleaning, then the process is simpler and faster, but contaminants decompose and deposit on the workpiece reducing quality

Engineering Contradiction:
Improveprocessing speedVSAvoidsurface quality
Core Design Contradiction:
ProductivityVSManufacturing precision

Solution Approach 1:

The patent merges the cleaning function into the heating process by using the same thermal field for both purposes. The burner used for heating also performs cleaning through controlled thermal decomposition, combining two operations into one continuous process that maintains high productivity while ensuring surface quality.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The patent performs preliminary thermal cleaning at a controlled cleaning temperature before the main heating to target temperature. This preliminary action removes residues that would otherwise decompose and contaminate the workpiece during subsequent heating, ensuring high surface quality without sacrificing processing efficiency.

Inventive Principle:
Principle #10Preliminary action

4Device complexity

If thermal cleaning is performed in the heating station, then the process is more compact, but pollutants from exhaust gases deposit on system parts

Engineering Contradiction:
Improvesystem integrationVSAvoidpollutant deposition
Core Design Contradiction:
Device complexityVSObject-generated harmful factors

Solution Approach 1:

The patent segments the thermal processing into distinct functional zones: a cleaning station for thermal decomposition and residue removal, and a separate heating station for forming temperature heating. This spatial segmentation prevents pollutants generated during cleaning from depositing on parts in the heating station, while maintaining system compactness through functional zonation.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent extracts the cleaning function into a separate cleaning station with its own extraction and purification system. By taking out the pollutant-generating thermal decomposition process from the main heating station, the method prevents contaminant deposition on heated parts while maintaining integrated system operation through coordinated processing.

Inventive Principle:
Principle #2Taking out (Extraction)

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 enhances the quality of the forged component by reducing the likelihood of permanent damage from contaminants and ensuring improved surface quality, while maintaining the workpiece's properties and preventing corrosion, by effectively removing residues and dust before the heating process.

Implementation Method 1

Caused by thermal processes that occur when the temperature required for the tempering process is reached, the substances that have been deposited on the semi-finished product undergo thermal decomposition

Methodology Applied
Scientific EffectThermal decomposition: Pyrolysis

Implementation Method 2

the workpiece is heated to a cleaning temperature by a burner in the cleaning step

Methodology Applied
Scientific EffectHeating: Heating

Implementation Method 3

when the workpiece is heated to a cleaning temperature, the air surrounding the workpiece is extracted, for example by means of a fume hood, in order to remove the pollutants

Methodology Applied
Scientific EffectExtraction: Suction

Data Source

PatentEP3221474B1Method for hot or warm forming a workpiece and production plant for hot or warm forming a workpiece
Publication Date: 2019.02.27 THYSSENKRUPP AG
  • EP3221474B1 patent drawingFigure 1a~1d

AI summary

The invention relates to a method for hot or warm forming a workpiece, said method comprising the following steps; the workpiece which is to be formed is provided, the workpiece is at least partially pretreated, the workpiece is at least partially heated to a target temperature and the workpiece is at least partially formed and/or hardened. The workpiece is at least partially cleaned in a cleaning step between the pretreatment and the warming.