Composite Cemented Carbide Roll Structure for Residual Stress Control
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Solution Overview
Problem
Existing composite cemented carbide rolls face issues with insufficient compressive yield strength, leading to dents on the roll surface during cold rolling and potential fatigue failure due to residual tensile stress in the inner and intermediate layers.
Innovation Solution
A composite cemented carbide roll structure comprising an outer layer and intermediate layer made of WC particles with an Fe-based binder phase, metallurgically bonded to a steel inner layer, with specific compositions and thicknesses to enhance bonding strength and reduce residual stress, thereby increasing compressive yield strength and preventing fatigue.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If cemented carbide is used for rolls to achieve wear resistance and surface quality, then rolling quality is improved, but the roll structure becomes complex and costly due to multiple assembly components
Solution Approach 1:
The invention combines the cemented carbide sleeve and shaft into a single integrated component through metallurgical bonding, eliminating the need for separate assembly components like spacers, fixing members, and disc springs. This merging approach maintains the wear resistance benefits while simplifying the overall structure and reducing assembly complexity
Solution Approach 2:
The invention uses composite materials by combining cemented carbide (for wear resistance) with a ductile metal core material (for toughness and structural support). This composite structure allows the roll to maintain excellent surface quality while achieving the mechanical strength needed to withstand rolling loads without complex assembly structures
2Strength
If cemented carbide sleeve is pressure-fixed to shaft using multiple components, then bonding strength is improved, but assembling cost and complexity increase significantly
Solution Approach 1:
The invention replaces the mechanical assembly system (multiple components with mechanical fastening) with a metallurgical bonding system. The cemented carbide is metallurgically bonded to the core material, creating a strong unified structure that eliminates the need for complex mechanical assembly components and reduces manufacturing costs
Solution Approach 2:
By merging the cemented carbide layer with the core material through metallurgical bonding, the invention creates a single integrated component that achieves strong bonding without requiring multiple separate assembly components, thereby reducing both assembling cost and complexity
3Device complexity
If outer layer and inner layer are directly bonded, then structure is simplified, but residual stress and bonding reliability deteriorate due to thermal expansion difference
Solution Approach 1:
The invention introduces an intermediate layer between the cemented carbide outer layer and the metal core. This intermediate layer acts as a mediator with thermal expansion properties that bridge the gap between the two materials, reducing thermal expansion mismatch and minimizing residual stress while maintaining bonding reliability
Solution Approach 2:
The invention changes the thermal expansion parameter gradient by introducing an intermediate layer with intermediate thermal expansion properties. This gradual transition in thermal expansion parameters from the cemented carbide to the core material reduces thermal stress and improves bonding reliability without significantly increasing structural complexity
4Duration of action of moving object
If intermediate layer with thick cemented carbide is used, then wear resistance is improved, but fatigue failure risk increases due to residual tensile stress in inner layer
Solution Approach 1:
The intermediate layer serves as a stress-distributing intermediary that reduces the concentration of residual tensile stress in the core material. By providing a gradual transition zone, it allows the thick cemented carbide outer layer to maintain wear resistance while preventing fatigue failure in the inner layer
Solution Approach 2:
The intermediate layer modifies the stress distribution parameters by creating a gradual transition in material properties from the cemented carbide to the core. This parameter gradient reduces peak residual tensile stress in the inner layer, preventing fatigue failure while maintaining the protective outer layer
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 effectively suppresses dent formation on the roll surface during cold rolling, enabling continuous high-quality rolling with a longer lifespan by ensuring the composite cemented carbide roll has compressive yield strength of 1200 MPa or more and bending strength of 1700 MPa or more.
Implementation Method 1
an outer layer and an intermediate layer which are made of cemented carbide and have compressive yield strength of 1200 MPa or more, and are metallurgically bonded to each other and to an inner layer
Implementation Method 2
the binder phase having a chemical composition comprising 0.5-10% by mass of Ni, 0.2-2.0% by mass of C, 0.5-5% by mass of Cr, and 0.1-5% by mass of W
Data Source
Figure 1~2
Figure 3~4
Figure 5
AI summary
This cemented carbide composite roll is characterized by being formed from a steel inner layer, an intermediate layer made from a cemented carbide containing WC particles, and an outer layer, wherein the cemented carbide configuring the outer layer contains 55-90 parts by mass of WC particles and 10-45 parts by mass of a binder phase that has a specific composition with Fe as the main component, the cemented carbide configuring the intermediate layer contains 30-65 parts by mass of WC particles and 35-70 parts by mass of a binder phase that has a specific composition with Fe as the main component, and, when defining c1 as the content of WC particles in parts by mass in the outer layer and c2 as the content of WC particles in parts by mass in the intermediate layer, it holds that 0.45 ≤ c2/c1 ≤ 0.85.