Sealing Strand with Extruded Thermoplastic Core and Vulcanized Elastomer
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing sealing strands for vehicle windows, made from jointly extruded thermoplastic and elastomer materials, face issues with shape impairment due to differential shrinkage and heat-induced vulcanization damage, leading to suboptimal service life and sealing effectiveness.
Innovation Solution
A sealing strand with a vulcanized elastomer sealing section and a thermoplastic core part, where the core part is extruded after vulcanization, and a thin film is used for a firm weld, ensuring dimensional stability and matching shrinkage to prevent shape impairments, with the core part differing in filling materials like fiberglass and talc.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the sealing section and core part are co-extruded in a single step, then the manufacturing process is simple and productive, but the core part suffers damage from vulcanization heat and differential shrinkage causes shape impairments
Solution Approach 1:
The manufacturing process is divided into two separate steps: first extruding the sealing section and vulcanizing it, then extruding the core part separately and connecting it to the already-vulcanized sealing section. This segmentation prevents the core part from being exposed to vulcanization heat while maintaining production efficiency through process optimization.
Solution Approach 2:
The sealing section is extruded and vulcanized in advance before the core part is extruded and connected. This preliminary action ensures that the sealing section is fully vulcanized and dimensionally stable before the core part is added, preventing heat damage to the core and shrinkage-related shape impairments.
2Reliability
If the sealing section is vulcanized to improve service life and sealing performance, then the elastomer properties are enhanced, but the core part material is damaged by the vulcanization heat
Solution Approach 1:
The process separates the vulcanization step from the core part extrusion step. The sealing section is vulcanized independently first, achieving full elastomer cross-linking and optimal properties, while the core part is extruded afterward in a separate step without exposure to damaging vulcanization temperatures.
Solution Approach 2:
The sealing section undergoes vulcanization as a preliminary step before the core part is extruded and connected. This ensures the elastomer achieves its full service life potential through complete vulcanization while the thermoplastic core part remains undamaged since it is processed after the heat treatment is complete.
3Manufacturing precision
If different filler materials are used in the core part to match shrinkage rates, then shape stability is improved, but the manufacturing process becomes more complex
Solution Approach 1:
The core part is divided into sections with different filler materials (e.g., glass fiber in one section, talc in another) to match the local shrinkage characteristics of adjacent sealing section areas. This local differentiation of material properties ensures uniform shrinkage behavior across the entire composite part, preventing shape impairments at the interface between different material zones.
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
The solution enhances the service life and sealing performance by avoiding core part damage from vulcanization heat and ensuring a stable connection, reducing shape impairments from differential shrinkage, resulting in improved durability and effectiveness.
Implementation Method 1
the sealing section is first extruded and, after its vulcanization
Implementation Method 2
the vulcanized sealing section is shrunk before being connected to the core part
Implementation Method 3
the remaining core part is extruded or injection-molded onto the core part section
Implementation Method 4
the sealing section is first extruded and, after its vulcanization
Implementation Method 5
heat supplied during vulcanization dissipates quickly into the material of the sealing section, so that the thermoplastic film remains dimensionally stable during vulcanization
Implementation Method 6
a core section connected to the remaining core part is extruded to the vulcanized sealing section by means of a material-locking or/and form-locking connection
Implementation Method 7
a core section connected to the remaining core part is extruded to the vulcanized sealing section by means of a material-locking or/and form-locking connection
Data Source
Figure 1~2
Figure 3
AI summary
The invention relates to a sealing strand for forming a seal on a vehicle body, in particular on a channel strip or window guide for sealing a movable vehicle window pane, with an extruded core part (2) composed of thermoplastic material and an extruded sealing portion (10) which is connected to the core part (2, 14) and is composed of elastomer material. According to the invention, the sealing portion (10) is composed of vulcanized elastomer material, in particular EPDM, and the core part (2, 14) or a core part portion (14) which is connected to the remaining core part (2) is extruded onto, and connected to, the vulcanized sealing portion (10). The invention further relates to a method for producing such a sealing strand.