Injection Molded Part With Deformable Metal Insert
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Solution Overview
Problem
Injection molded parts in automobile construction face a challenge in reducing weight while maintaining strength, as metal inserts with higher tolerances are complex to manufacture and increase production costs, and solely plastic screw connections do not meet strength requirements.
Innovation Solution
A sleeve-shaped metal insert with a projection that allows deformation under clamping force, distributing the force into a larger plastic body, and a method of injection molding where the insert is plastically deformed within the mold to achieve accurate geometric dimensions and reduced manufacturing complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If metal inserts with higher strength and tighter tolerances are used to meet strength requirements, then the screw connection strength is sufficient, but the manufacturing complexity and cost increase
Solution Approach 1:
The patent changes the geometric parameters of the insert by adding a projection element that extends into the plastic body. This projection has specific dimensional parameters (height, diameter) that are optimized to distribute stresses and improve the screw connection strength without requiring tighter manufacturing tolerances on the insert itself
Solution Approach 2:
The projection is pre-formed as an integral part of the insert before insertion into the plastic body. This preliminary structuring of the insert creates a force distribution mechanism that is already in place before the screw is tightened, allowing the insert to handle higher loads without requiring post-manufacturing adjustments or tighter tolerances
2Strength
If metal inserts with larger dimensions are used to absorb more clamping force, then the screw connection strength is sufficient, but the insert weight increases
Solution Approach 1:
Instead of uniformly increasing the insert dimensions throughout, the patent applies a localized projection only in the region where force transmission to the plastic body is needed. This local addition of material provides the necessary strength for clamping force absorption while minimizing the overall weight increase of the insert
3Strength
If the plastic body is made larger to safely absorb forces from the insert, then the strength requirements are met, but the overall part weight increases
Solution Approach 1:
The patent segments the force absorption function between the insert and the plastic body by introducing a projection. The projection handles the stress concentration and force distribution, while the plastic body only needs to provide sufficient material around the projection. This segmentation allows the plastic body to be smaller than it would need to be without the projection
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 allows for a lighter, cost-effective injection molded part with improved strength and reduced manufacturing effort, enabling a higher percentage of clamping force to be absorbed by the insert, thus reducing the insert's dimensions and weight while maintaining stability.
Implementation Method 1
the insert part can be deformed due to the clamping force in such a way that a predetermined part of the clamping force of the screw can be introduced into the screw contact surface
Implementation Method 2
the injection mold is closed in such a way that the insert is plastically deformed
Data Source
Figure 1~2
Figure 3a~3c
Figure 4~5
AI summary
The invention relates to an injection molded part, comprising a sleeve-shaped insert (18) made of metal, which has a longitudinal axis (L), an end face (26), a recess (46) which runs through the end face (26), passes through the insert (18) and is designed such that a screw (48) can be inserted therethrough, and additionally has an outer lateral surface (50). The injection molded part also comprises a plastic body (44) that surrounds the outer lateral surface (50) and has a screw contact surface (28) which extends along a contact plane (52) running perpendicular to the longitudinal axis (L) and, with respect to a height, along the longitudinal axis (L) in the region of the end face (26). According to the invention, the screw contact surface (28) has a countersinking (S) with respect to the end face (26), wherein the countersinking (S) is so large and the insert (18) has such a spring constant (k) with respect to the longitudinal axis (L) that, by exerting a clamping force (FSpann) perpendicularly to the end face (26) by means of the screw (48), the insert (18) can be deformed on the basis of the clamping force (FSpann) such that a predetermined component of the clamping force (FSpann) of the screw (48) can be introduced into the screw contact surface (28).