Ceramic Roller Sleeve Geometry for High-Temperature Torque Transmission

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Solution Overview

Problem

The connection between ceramic rollers and steel bearing elements in roller hearth furnaces is compromised at high temperatures due to the difference in thermal expansion coefficients, leading to a reduced interference fit and impaired torque transmission.

Innovation Solution

A sleeve design with a waist section and clamping section, featuring a reduced wall thickness and cross-sectional area, allows for a frictional and force-fit connection of ceramic rollers in the furnace, maintaining stability and torque transmission despite thermal expansion differences.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a metal sleeve is mounted externally on the ceramic roller, then the ceramic roller can be connected to the drive and bearing assembly, but the interference fit is reduced at high operating temperature due to the higher coefficient of thermal expansion of steel compared to ceramic

Engineering Contradiction:

Improveconnection reliabilityVSAvoidoperating temperature

Core Design Contradiction:

ReliabilityVSTemperature

Solution Approach 1:

The patent changes the geometric parameters of the sleeve by introducing a waist section with reduced wall thickness and a clamping section with reduced cross-sectional area. This parameter modification allows the sleeve to maintain sufficient interference fit at high temperatures while still enabling connection between the ceramic roller and drive assembly.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The sleeve is segmented into different functional sections: a waist section with reduced wall thickness for flexibility and a clamping section with reduced cross-sectional area for maintaining interference fit. This segmentation allows each section to perform its specific function optimally under thermal expansion conditions.

Inventive Principle:

Principle #1Segmentation

2Adaptability or versatility

If the wall thickness of the sleeve is reduced in the waist section, then the sleeve can accommodate thermal expansion differences, but the structural strength of the sleeve is reduced

Engineering Contradiction:

Improvethermal expansion accommodationVSAvoidsleeve strength

Core Design Contradiction:

Adaptability or versatilityVSStrength

Solution Approach 1:

The sleeve exhibits local quality variations with different wall thicknesses in different sections. The waist section has reduced wall thickness to accommodate thermal expansion, while other sections maintain sufficient thickness for structural strength. This localized differentiation allows the sleeve to simultaneously achieve adaptability and strength.

Inventive Principle:

Principle #3Local quality

3Reliability

If the cross-sectional area of the receptacle is reduced in the clamping section, then the interference fit is maintained at high temperature, but the manufacturing complexity increases

Engineering Contradiction:

Improveinterference fit maintenanceVSAvoidsleeve manufacturing

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent modifies the cross-sectional area parameter of the receptacle in the clamping section to create a reduced area that maintains interference fit at high temperatures. This parameter change is achieved through a controlled manufacturing process that reduces the cross-sectional area in the specific clamping section while maintaining overall manufacturability.

Inventive Principle:

Principle #35Parameter changes

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 sleeve provides a reliable and stable connection for ceramic rollers in high-temperature environments, ensuring effective torque transmission and simplified manufacturing without the need for additional slots or springs.

Implementation Method 1

the cross-sectional area of the receptacle is smaller in a clamping section than in the surrounding area of the receptacle... allowing for a frictional and force-fit connection... maintaining stability and torque transmission despite thermal expansion differences

Methodology Applied

Scientific EffectElastic deformation: Elasticity

Implementation Method 2

Since steel has a significantly higher coefficient of thermal expansion than ceramic, the interference fit of a friction-fit connection is reduced at the high operating temperature

Methodology Applied

Scientific EffectThermal expansion: Thermal Expansion

Data Source

PatentEP4118391B1Mounting a ceramic roller in a roller hearth furnace

Publication Date: 2026.01.21 SCHWARTZ GMBH

Figure 1~2
Figure 3~4
Figure 5~6

AI summary

The invention relates to a sleeve (3) for mounting a ceramic roller (2) in a roller hearth furnace (1), the sleeve (3) having a receptacle (4) for one end (5) of the ceramic roller (2), the receptacle (4) being surrounded by a cylinder wall (6), the cylinder wall (6) having, in the axial direction, a waist portion (7) and a clamping portion (8) located therein. The wall thickness (d) of the cylinder wall (6) in the waist portion (7) is smaller than in the vicinity of the waist portion (7), and a cross-sectional area of the receptacle (4) in the clamping portion (8) is smaller than in the vicinity of the clamping portion (8). A ceramic roller (2) can be mounted particularly reliably in a roller hearth furnace by means of the sleeve (3), even at high temperature. To achieve this, during production the sleeve (3) is provided with a reduced cross-sectional area in the clamping portion (8). When the sleeve (3) is pressed axially onto the end (5) of a ceramic roller (2), the reduced cross-sectional area in the clamping portion (8) produces an elastic force, by means of which the sleeve (3) is held on the ceramic roller (2).