CFC Workpiece Carrier with Ceramic Positioning Devices

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Solution Overview

Problem

Existing workpiece carriers for high-temperature treatments face issues with dimensional stability and contamination prevention, as metal support struts can warp or sag, and ceramic coatings are prone to cracking and wear due to thermal expansion differences.

Innovation Solution

A workpiece carrier with a support grid of carbon fiber-reinforced carbon (CFC) struts and positioning devices made of ceramic fiber composite material, which are thicker, stable, and resistant to temperature changes, preventing contamination by allowing workpieces to rest exclusively on the ceramic elements.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If metal support struts are used in workpiece carriers, then ease of manufacture is improved, but dimensional stability deteriorates at high temperatures due to warping and bending

Engineering Contradiction:
Improveease of manufactureVSAvoiddimensional stability
Core Design Contradiction:
Ease of manufactureVSStability of the object's composition

Solution Approach 1:

The patent applies composite materials by using carbon fiber reinforced carbon (CFC) for support struts requiring high-temperature dimensional stability, while using ceramic materials for positioning devices requiring chemical inertness. This composite approach allows each material to be used where its properties are most beneficial, resolving the contradiction between ease of manufacture and dimensional stability at high temperatures.

Inventive Principle:
Principle #40Composite materials

2Object-affected harmful factors

If ceramic coatings are applied to CFC support struts to prevent contamination, then contamination prevention is improved, but reliability deteriorates due to cracking and flaking from thermal expansion differences

Engineering Contradiction:
Improvecontamination preventionVSAvoidreliability
Core Design Contradiction:
Object-affected harmful factorsVSReliability

Solution Approach 1:

The patent extracts the contamination prevention function from the support struts and relocates it to dedicated positioning devices made entirely of ceramic materials. This separation eliminates the thermal expansion mismatch problem that caused coating failure, while still achieving contamination prevention through the chemically inert ceramic positioning devices that contact the workpieces.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent introduces ceramic positioning devices as intermediary elements between the CFC support struts and the metal workpieces. These positioning devices serve as a mediator that prevents direct contact between carbon-containing struts and metal workpieces, thereby preventing carburization without requiring thermal expansion-matched coatings on the struts themselves.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Object-affected harmful factors

If ceramic positioning devices are used to prevent contamination, then contamination prevention is improved, but mechanical strength deteriorates due to brittleness and susceptibility to thermal shock

Engineering Contradiction:
Improvecontamination preventionVSAvoidmechanical strength
Core Design Contradiction:
Object-affected harmful factorsVSStrength

Solution Approach 1:

The patent applies local quality by using ceramic materials specifically for the positioning devices where chemical inertness is critical for contamination prevention, while using CFC for the support struts where mechanical strength and thermal shock resistance are paramount. This localized material assignment optimizes both contamination prevention and mechanical strength in their respective locations.

Inventive Principle:
Principle #3Local quality

4Stability of the object's composition

If CFC support struts are used to ensure dimensional stability, then dimensional stability is improved, but object-generated harmful factors worsen due to potential carburization of workpieces

Engineering Contradiction:
Improvedimensional stabilityVSAvoidcontamination
Core Design Contradiction:
Stability of the object's compositionVSObject-generated harmful factors

Solution Approach 1:

The patent introduces ceramic positioning devices as intermediary elements between the CFC support struts and the metal workpieces. These positioning devices serve as a mediator that prevents direct contact between carbon-containing struts and metal workpieces, thereby preventing carburization while maintaining the dimensional stability benefits of CFC struts.

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

The solution provides a cost-effective, dimensionally stable, and contamination-free workpiece carrier that maintains structural integrity and prevents undesired material transfer during high-temperature treatments, allowing for efficient and secure handling of workpieces.

Implementation Method 1

Support struts made of carbon fiber reinforced carbon (CFC), on the other hand, are dimensionally stable and sufficiently strong even at high temperatures.

Methodology Applied
Scientific EffectThermal stability of carbon fiber reinforced carbon:

Implementation Method 2

The round bars are made of an extruded ceramic material and are not thermal shock resistant, meaning that the round bars can be easily damaged by the formation of cracks during rapid temperature changes.

Methodology Applied
Scientific EffectThermal shock resistance: Thermal Shock

Implementation Method 3

For example, undesirable carburization of steel, a workpiece material, can occur if it rests directly against a positioning device made of carbon fiber reinforced carbon.

Methodology Applied
Scientific EffectCarburization prevention: Carburizing

Data Source

PatentEP3379189B1Workpiece holder and method for manufacturing the same
Publication Date: 2019.09.04 SCHUNK KOHLENSTEOFFTECHNIK GMBH
  • EP3379189B1 patent drawingFigure 1
  • EP3379189B1 patent drawingFigure 2
  • EP3379189B1 patent drawingFigure 3

AI summary

The invention relates to a workpiece carrier and a method for manufacturing a workpiece carrier (10) for providing and handling workpieces in high-temperature furnaces for high-temperature treatment or the like, wherein the workpiece carrier is formed from a support grid (11) with workpiece receptacles (12) for positioning workpieces on the workpiece carrier, wherein the support grid is formed from support struts (14, 15, 16, 17, 19, 20) forming a grid structure (21), wherein the support struts are made of carbon fiber reinforced carbon (CFC), wherein the workpiece receptacles are formed from positioning devices (22) of the workpiece carrier arranged on the support struts, wherein the positioning devices are designed and arranged on the support struts such that workpieces can be arranged on the workpiece receptacles in a predetermined position, wherein the positioning devices have a support element (24) for arranging workpieces.wherein the support element is made of a ceramic fiber composite material, wherein the positioning device has a support element (23) arranged on a support strut for arranging the support element.