Thermoplastic Insert Joining with Interference Fit Anchoring
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Solution Overview
Problem
Existing methods for joining objects with thermoplastic inserts in penetrable materials, such as wood or structural foam, often result in non-uniform lateral anchorage and require significant time and energy, especially when the anchoring area is large.
Innovation Solution
Establishing an interference fit between the insert and the opening, followed by the application of mechanical vibration to liquefy the thermoplastic material, allowing it to penetrate the penetrable material, resulting in a strong and uniform lateral anchorage without the need to move the insert significantly within the opening.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If mechanical vibration and pressing force are applied simultaneously to advance the insert into the opening, then the thermoplastic material is liquefied and penetrates the fibrous or porous material, but the bulk of the insert must be moved significantly during vibration application, increasing time and energy consumption
Solution Approach 1:
The insert is positioned in the opening before vibration is applied, establishing initial contact between the thermoplastic material and the fibrous or porous material. This preliminary positioning eliminates the need to move the bulk of the insert during vibration, as the material is already in place to be liquefied and anchored laterally.
Solution Approach 2:
The anchoring process is divided into two distinct steps: first positioning the insert (without significant force), then applying vibration to liquefy and anchor the material laterally. This segmentation allows the bulk insert to remain stationary while only the contact material undergoes phase change and lateral penetration.
2Manufacturing precision
If the insert cross-section is adapted to the opening cross-section for interference fit, then positioning is improved, but the insert must be forced into the opening requiring significant force before vibration can be effective
Solution Approach 1:
The insert is positioned in the opening without applying significant forcing force before the vibration step. The preliminary positioning establishes the correct location and orientation, while the subsequent vibration provides the energy needed to overcome any interference fit resistance and liquefy the thermoplastic material for lateral anchorage.
3Strength
If vibration is applied to liquefy thermoplastic material for lateral anchorage, then anchorage strength is achieved, but significant energy is consumed and strain is placed on the vibrating tool
Solution Approach 1:
The insert is positioned and the thermoplastic material is brought into contact with the fibrous or porous material before vibration is applied. This preliminary arrangement ensures that when vibration is applied, the energy is efficiently used to liquefy and anchor the material that is already in the correct position, rather than wasting energy moving the bulk insert.
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 method achieves a high uniformity of lateral anchorage strength comparable to existing methods but reduces the time and energy required, while maintaining the quality of the joint and minimizing strain on the vibrating tool.
Implementation Method 1
the material having thermoplastic properties is liquefied due to friction heat at least where in contact with the fibrous or porous material
Implementation Method 2
mechanical vibration, in particular ultrasonic vibration
Implementation Method 3
the material having thermoplastic properties is liquefied due to friction heat and it penetrates into the fibrous or porous material of the walls of the opening
Implementation Method 4
forms on re-solidification a positive fit connection with the porous or fibrous material
Data Source
AI summary
A method for joining two objects by anchoring an insert portion provided on one of the objects in an opening provided on the other one of the objects. The anchorage is achieved by liquefaction of a thermoplastic material and interpenetration of the liquefied material and a penetrable material, the two materials being arranged on opposite surfaces of the insert portion and the wall of the opening. Before such liquefaction and interpenetration, an interference fit is established in which such opposite surfaces are pressed against each other, and, for the anchoring, mechanical vibration energy and possibly a shearing force are applied, wherein the shearing force puts a shear stress on the interference fit.