Deformable Insert Composite Casting to Prevent Bonding Cracks
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Solution Overview
Problem
Composite castings often experience cracking in the bonding zone due to tensile stresses caused by volume shrinkage during solidification and cooling, leading to impaired mechanical, electrical, and thermal properties, particularly in components requiring optimal connections like hybrid-cast rotors and heat spreaders.
Innovation Solution
A method involving a deformable insert, such as a copper rod or fiber-reinforced plastic, is used where the insert is designed to yield to tensile stresses through geometric configurations or intermetallic phases, allowing it to deform with the cast metal and prevent crack formation by managing volume shrinkage and tensile forces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the insert is made rigid to maintain structural integrity, then the mechanical strength is improved, but cracking occurs in the bonding zone due to tensile stresses from volume shrinkage
Solution Approach 1:
The insert is designed with deformable geometric configurations (such as relief cuts, cavities, or flexible structures) that allow it to dynamically adapt its shape during solidification. This enables the insert to yield to tensile stresses caused by volume shrinkage, preventing crack formation in the bonding zone while maintaining structural integrity after solidification.
Solution Approach 2:
The insert's geometric parameters are specifically designed to change during the casting process. The insert transitions from a compressed or deformed state during solidification to its final operational shape, allowing it to accommodate volume shrinkage stresses without cracking.
2Reliability
If the insert is made deformable to accommodate volume shrinkage, then cracking is prevented, but the mechanical strength may be reduced
Solution Approach 1:
The insert employs dynamic geometric features that provide deformability only during the critical solidification phase. After solidification, the insert maintains its structural strength through its final geometric configuration, which may include relief cuts or flexible structures that have already accommodated the shrinkage stresses.
Solution Approach 2:
The insert is pre-compressed or pre-deformed before casting to anticipate the volume shrinkage that will occur during solidification. This preliminary action allows the insert to yield to tensile stresses in advance, preventing crack formation while maintaining its final structural integrity.
3Reliability
If the surface area of the bonding zone is increased to mitigate cracking impact, then the reliability is improved, but the device complexity increases
Solution Approach 1:
The bonding zone is segmented into multiple smaller bonding interfaces through the insert's geometric features (such as relief cuts or cavities). This segmentation distributes the tensile stresses across multiple smaller bonding areas, reducing the impact of any single crack and improving overall reliability without requiring a large increase in total bonding surface area.
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
This approach results in crack-free or low-crack composite components with enhanced electrical and thermal conductivity, suitable for complex shapes and large-area components, particularly in motor vehicle construction and asynchronous machines, by reducing stress and promoting effective heat dissipation.
Implementation Method 1
The insert is designed to be deformable, so that any volume shrinkage of the casting causes deformation of the insert via the bond between the casting and the insert. This deformation follows the volume shrinkage and thus avoids tears or breaks between the cast metal and the insert.
Implementation Method 2
the cause of cracking lies in tensile stresses in the composite layer, which arise when volume shrinkage occurs during the solidification of the metal casting and the cooling of the cast or encased insert
Implementation Method 3
the bond is a metallurgical bond, achieved through the formation of an intermetallic phase between the insert and the casting, or between an intermediate layer (e.g., tin) on the insert and the casting
Implementation Method 4
This bond is a positive-locking connection formed by the infiltration of a surface structure of the insert into the casting
Data Source
Figure 1a~2
Figure 3a~6b
Figure 7a~9
AI summary
The invention relates to a method for joining an insert (2) to a cast metal (1) to form a composite component by casting. In this process, a connection is created between the cast metal (1) and the insert (2) during the casting process. This connection is achieved either as a positive-locking connection by infiltration of a surface structure of the insert (2) with the cast metal (1) and/or as a metallurgical connection by the formation of an intermetallic phase between the insert (2) and the cast metal (1). The insert (1) is designed to be deformable, such that when the cast metal shrinks (A) through the connection between the cast metal (1) and the insert (2), a deformation (C) of the insert (2) occurs, following the shrinkage (A), thus preventing cracks or breaks between the cast metal (1) and the insert (2). The invention also relates to a correspondingly manufactured composite component.