Dual Material Device Chamfer Design for Pin Assembly
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Solution Overview
Problem
The assembly of bi-material devices, such as engine casings, often faces issues with centering pin fitting due to the metallurgical differences between materials like cast iron and aluminum, leading to high fitting pressure and potential damage during the assembly process.
Innovation Solution
The entry chamfer of the bore extends beyond the joining plane, providing a slight lateral movement for the pin, ensuring correct alignment and preventing seizing by maintaining a sufficient diameter difference between the chamfer and the pin, thus facilitating smooth assembly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the bore has a standard entry chamfer design, then the pin fitting section provides secure clamping, but the shoulder formed at the joining plane causes seizing during pin introduction
Solution Approach 1:
The entry chamfer is designed to extend beyond the joining plane before pin insertion occurs. This preliminary geometric configuration creates a clearance zone that prevents the shoulder from interfering with pin introduction, allowing the pin to be guided into position before engaging the fitting section for secure clamping.
Solution Approach 2:
The solution adds a dimensional element to the chamfer design by extending it axially beyond the joining plane. This creates a three-dimensional clearance zone that resolves the two-dimensional conflict between the shoulder obstruction and pin passage, allowing both the shoulder to form for clamping and the pin to pass freely during introduction.
2Ease of operation
If the entry chamfer diameter is larger than the pin diameter, then lateral movement and guidance are enabled, but the fitting section must be precisely controlled to ensure proper clamping
Solution Approach 1:
The invention changes the dimensional parameters of the bore geometry by specifying that the entry chamfer diameter must be strictly greater than the pin diameter. This parameter modification enables the desired lateral movement and guidance function while the fitting section maintains its precise dimensions for proper clamping, resolving the contradiction through controlled parameter variation.
Data Source
Figure 1
Figure 4~5
AI summary
The invention relates to a dual material device that includes an insert (12), a part (14) made of a material other than that of the insert, the insert and the part being assembled by moulding one around the other, the interface between the insert and the part defining at least one junction plane (40), and a bore (26, 28) for receiving a pin, formed in said device and extending through the junction plane, wherein the bore includes an inlet chamfer (36) for guiding the pin up to a pin engagement section (38), characterised in that the inlet chamfer (36) extends beyond the junction plane (40).