Thermal Press-Fit Roll Connection for Molten Metal Handling
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Solution Overview
Problem
Ceramic or carbon composite rolls used in molten metal baths are prone to breakage due to force concentration between the roll and the shaft, and existing solutions fail to provide a reliable method for supporting and rotating these rolls without damage.
Innovation Solution
A connection part comprising three successive parts, including a first part for insertion into a bushing, a second part with fastening means attached to the roll, and a third part with a parallelepiped section for pressfitting when immersed in the molten metal, made of a material with a higher thermal expansion coefficient than the roll, ensuring secure rotation and handling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a shaft is inserted into a hollow roll to support and rotate it, then the roll can be handled and rotated, but the roll breaks due to force concentration between the roll and shaft
Solution Approach 1:
The connection part is divided into three successive parts: a first part connecting with the bushing, a second part with fastening means attached to the roll side, and a third part inserted inside the roll. This segmentation distributes the mechanical stresses across different locations and reduces force concentration that would otherwise cause roll breakage.
Solution Approach 2:
The connection part is made of a material with a higher thermal dilatation coefficient than the roll, and the coefficient is chosen so that the third part and roll are pressfitted through thermal dilatation when in the molten metal bath. This thermal expansion parameter change creates a secure pressfit connection without requiring excessive mechanical force during assembly.
2Reliability
If new inert rolls made of ceramic or carbon composite are used to replace metallic rolls, then resistance against corrosion and wear increases, but the rolls break due to force concentration
Solution Approach 1:
The connection part uses a composite approach by combining a metallic material (with higher thermal expansion coefficient) for the connection components with the inert roll material (ceramic or carbon composite). This allows the inert roll to maintain its corrosion and wear resistance while the metallic connection part provides the necessary mechanical strength and thermal expansion properties for secure attachment.
Solution Approach 2:
The connection part is made of a material with a higher thermal dilatation coefficient than the roll, enabling pressfitting through thermal dilatation when immersed in the molten metal bath. This thermal expansion mechanism creates a secure connection without damaging the inert roll material.
3Power
If a pressfit connection is used to secure the roll to the shaft, then torque transmission is improved, but the roll may break due to excessive force concentration
Solution Approach 1:
The thermal expansion coefficient difference between the connection part and roll is specifically chosen to enable pressfitting only when heated in the molten metal bath. At operating temperature, the thermal expansion creates an optimal pressfit that transmits torque effectively without excessive force concentration that would damage the roll.
Solution Approach 2:
The pressfit connection is activated through thermal expansion when the equipment is immersed in the molten metal bath. The connection part expands more than the roll due to its higher thermal dilatation coefficient, creating a secure fit that transmits torque while distributing forces safely.
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 allows the roll to rotate securely and be handled safely without damage, with a controlled pressfit that prevents breakage and ensures efficient torque transmission, even under high temperatures and corrosive conditions.
Implementation Method 1
said connection part 7 being made of a material having a higher thermal dilatation coefficient than said roll 5, said coefficient being chosen so that said third part 12 and said roll 5 are pressfitted through thermal dilatation when in the molten metal bath 3
Data Source
Figure 1~2
Figure 3~4b
Figure 5~7D
AI summary
The present invention relates to a method and an equipment permitting to optimally handle and support a roll made of at least an inert material and transfer the torque from a bearing to a roll or the other way around without damaging them. Said roll and bearing being immersed in molten metal.