Chamfered Raw Setter for Isotropic Honeycomb Firing Shrinkage

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Solution Overview

Problem

Honeycomb structures face defects such as deformation and fissures during firing due to non-isotropic firing shrinkage, especially when cell partition walls are thin, caused by uneven contact with traditional raw setters, leading to shape and roundness issues.

Innovation Solution

A raw setter with a chamfered portion and tapered cross-sectional shape, made of the same material as the honeycomb body, is used to facilitate isotropic firing shrinkage by reducing contact area and improving surface flatness, allowing uniform contact and minimizing restraints during firing.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If a traditional raw setter with large contact area is used, then the honeycomb formed body is well-supported during firing, but non-isotropic firing shrinkage occurs causing deformation and fissures

Engineering Contradiction:
Improvesupport capabilityVSAvoidshape accuracy
Core Design Contradiction:
StrengthVSManufacturing precision

Solution Approach 1:

The raw setter surface is segmented into multiple small contact points rather than a large continuous contact area. The convex protrusions create discrete contact regions that allow isotropic shrinkage while providing sufficient support, resolving the contradiction between support capability and shape accuracy.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The raw setter has different surface qualities in different regions: convex protrusions for contact with the honeycomb formed body and concave portions for clearance. This local differentiation allows the setter to provide support only where needed while minimizing restraint on shrinkage, improving both support capability and shape accuracy.

Inventive Principle:
Principle #3Local quality

2Manufacturing precision

If the contact area between raw setter and honeycomb formed body is reduced, then isotropic firing shrinkage is achieved, but the honeycomb formed body may be crushed by its own weight

Engineering Contradiction:
Improveisotropic shrinkageVSAvoidstructural integrity
Core Design Contradiction:
Manufacturing precisionVSStrength

Solution Approach 1:

The support function is segmented into multiple convex protrusions distributed across the raw setter surface. This segmentation provides sufficient total support area to prevent crushing while maintaining small individual contact points that allow isotropic shrinkage, resolving the contradiction between structural integrity and isotropic shrinkage.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The convex protrusions are arranged to provide uniform support distribution across the honeycomb formed body base. This equipotential support arrangement ensures that the body weight is evenly distributed, preventing localized crushing while maintaining conditions for isotropic shrinkage.

Inventive Principle:
Principle #12Equipotentiality

3Ease of operation

If the raw setter has a flat surface for uniform contact, then easy alignment is achieved, but firing shrinkage is restrained causing deformation

Engineering Contradiction:
Improvealignment easeVSAvoidshrinkage freedom
Core Design Contradiction:
Ease of operationVSManufacturing precision

Solution Approach 1:

The flat surface is segmented into convex protrusions and concave portions. The convex protrusions provide discrete contact points that minimize shrinkage restraint while the overall flat arrangement maintains alignment ease, resolving the contradiction between alignment ease and shrinkage freedom.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The convex protrusions act as intermediaries between the raw setter flat surface and the honeycomb formed body. They transmit support forces while minimizing contact area, allowing the flat surface to provide alignment guidance without restraining shrinkage.

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 enables the honeycomb body to undergo isotropic firing shrinkage, reducing the likelihood of deformation and fissures, and maintaining the shape and roundness of the honeycomb structure, thereby improving the quality of the fired product.

Implementation Method 1

The extruded honeycomb formed body carries out a firing shrinkage along a longitudinal direction of cells and a direction orthogonal to the cell longitudinal direction in the firing step

Methodology Applied
Scientific EffectFiring shrinkage: Thermal Contraction

Data Source

PatentEP3023723B1Raw setter, and firing method of honeycomb formed body
Publication Date: 2018.04.11 NGK INSULATORS LTD
  • EP3023723B1 patent drawingFigure 1~2
  • EP3023723B1 patent drawingFigure 3~4
  • EP3023723B1 patent drawingFigure 5~6

AI summary

There is disclosed a raw setter which enables a honeycomb formed body to isotropically carry out a firing shrinkage without restraining the honeycomb formed body. A raw setter 1 has a plate shape, is made of the same material as in a honeycomb formed body 100, and has a chamfered portion 10 in which a circumferential portion 11 of one end face 12 is chamfered in an oblique direction and whose has a tapered cross-sectional shape by reducing a diameter of an end face portion to an outer diameter, a ratio of an area of a flat portion 12a to an end face area is from 10 to 85%, an angle formed between the flat portion 12a and the chambered portion 10 is from 3 to 50°, a flatness of each of the flat portion 12a of the one end face 12 and a flat portion of the other end face 16 is 0.3 mm or less, and a thickness of cell partition walls is 0.1 mm or less.