Creep-Sensitive Part Positioning via Overmolded Annular Inserts
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Solution Overview
Problem
Conventional positioning methods for parts made of creep sensitive materials, such as thermoplastics or elastomers, face challenges including deformation under heat or tightening stresses, and require additional complex components like centering posts or oblong compression limiters, which increase costs and complexity while risking damage during handling.
Innovation Solution
The method involves equipping the mold for molding one part with a spindle and an annular metal insert, which is overmolded with the creep sensitive material to create a centering hole, preventing creep deformation and allowing precise positioning using screws or pins, with the annular insert serving as a compression limiter.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If centering holes are equipped with spacers to limit compression and reduce deformation, then the firm clamping of assembled parts is guaranteed over time, but the parts create fragile zones or weak points and require additional complex components
Solution Approach 1:
The patent merges the centering function and compression limiting function into a single integrated annular insert. This insert is molded directly into the part during the injection molding process, eliminating the need for separate spacers or compression limiters that would need to be pressed into the part afterward. The annular insert provides both the centering geometry and the compression limiting capability in one component, thereby reducing device complexity while maintaining reliability.
Solution Approach 2:
The annular insert is prepared and integrated into the part during the molding process itself, before the part is removed from the mold. This preliminary action ensures that the compression limiter is already in place and properly positioned before assembly, eliminating the need for subsequent operations to install separate spacers or compression limiters.
2Manufacturing precision
If oblong compression limiters with larger diameter are used, then positioning precision is improved, but the compression limiters are difficult to handle when pressing into preformed receiving holes
Solution Approach 1:
The annular insert with the required larger diameter for precise positioning is integrated into the part during the molding process itself. The insert is held in the mold and the creep sensitive material is molded around it, so the insert is already in its final position before the part is removed from the mold. This eliminates the handling and pressing difficulties that would occur if trying to install a large-diameter compression limiter into a preformed hole afterward.
Solution Approach 2:
The mold cavity acts as an intermediary that facilitates the integration of the annular insert into the part. The mold holds the insert in the correct position and provides the necessary force and pressure during the injection molding process to securely integrate the insert into the part, thereby avoiding the handling difficulties associated with manual pressing operations.
3Manufacturing precision
If compression limiters are pressed into preformed receiving holes, then positioning is achieved, but the process may generate splinters or damage the receiving hole
Solution Approach 1:
The annular insert is integrated into the part during the molding process, before the part is removed from the mold. The insert is held in the mold and the creep sensitive material is molded around it, so the insert becomes an integral part of the molded component. This eliminates the need for subsequent pressing operations that would generate splinters or damage the receiving hole.
Solution Approach 2:
The mold cavity acts as an intermediary that facilitates the integration of the annular insert into the part without causing damage. The mold provides controlled pressure and support during the injection molding process, ensuring that the insert is properly integrated without generating splinters or damaging the receiving hole, which would occur with manual or mechanical pressing operations.
4Manufacturing precision
If centering posts or guide pins are molded on one part and placed into centering holes, then positioning is achieved, but the system creates fragile zones and requires supplemental elements that increase complexity
Solution Approach 1:
The patent merges the centering function and compression limiting function into a single integrated annular insert. This insert is molded directly into the part during the injection molding process, eliminating the need for separate centering posts, guide pins, or compression limiters. The annular insert provides both functions in one component, thereby reducing device complexity while maintaining positioning accuracy.
Solution Approach 2:
The annular insert serves multiple functions simultaneously: it provides centering geometry for precise positioning, acts as a compression limiter to prevent over-compression of the part, and serves as an integral part of the molded component. This multi-functionality eliminates the need for multiple separate components and reduces overall device complexity.
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 enables precise positioning and assembly of parts without deformation, reducing complexity and costs by using annular inserts as both compression limiters and assembly aids, ensuring accurate alignment and secure assembly.
Implementation Method 1
parts made of a creep sensitive material such as for example a thermoplastic, a thermosetting material or an elastomer... deformation of the part by creep under the action of temperature
Data Source
AI summary
Disclosed is a method and apparatus for positioning and assembly of two or more parts wherein at least one of which is of a creep sensitive material. The method and apparatus enable very precise positioning of parts during assembly by holding a rough alignment with free play permitting finer alignment. Creep resistant annular inserts are molded into the part and provided with flow apertures to conduct plastic material into the annular insert bore. A spindle defined the geometry of a centering hole within the bore during molding. The annular inserts are operable as compression limiters to prevent deformation of the creep sensitive material under the action of heat or tightening stresses.