Wiper Blade Extrusion with Thermoplastic Lip on Vulcanized Elastomer
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Solution Overview
Problem
Extruded profiles for windshield wipers suffer from deformation due to gravity and lack of dimensional stability, leading to functional losses, as they are not fully crosslinked when exiting the extruder, and require different material properties for the base and lip sections which are challenging to achieve with existing coextrusion methods.
Innovation Solution
The method involves separately producing a first profile with a simpler cross-section from elastomeric material and a second profile from thermoplastic material, which is extruded onto the first profile after it has cooled and been vulcanized, providing better adhesion and dimensional stability, and using high-temperature-resistant thermoplastics to eliminate the need for metallic spring rails.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the extruded profile is produced as a complex multi-material structure in one step, then different material properties can be achieved for base and lip sections, but the profile suffers from deformation due to gravity and lack of dimensional stability
Solution Approach 1:
The production process is divided into two separate steps: first producing a base profile with elastomeric material, then adding the lip section with different material properties through a subsequent extrusion process. This segmentation allows each section to be optimized independently while avoiding the deformation problems of complex one-step coextrusion.
Solution Approach 2:
The base profile is first produced and vulcanized to achieve dimensional stability before the lip section is added. This preliminary action ensures that the base structure is stable and can support the additional material without deformation, solving the gravity-induced deformation problem.
2Adaptability or versatility
If coextrusion process is used to produce base and lip sections with different properties, then material requirements can be met, but the process is complex and requires precise control to avoid deformation
Solution Approach 1:
The complex coextrusion process is segmented into two simpler processes: first extruding the base profile, vulcanizing it, then extruding the lip section separately. This reduces device complexity while maintaining the ability to produce multi-material structures with different properties.
Solution Approach 2:
The base profile is fully vulcanized before the lip section is extruded, creating a stable substrate that simplifies the subsequent extrusion process. This preliminary vulcanization action reduces the complexity of controlling the extrusion process while ensuring different material properties are achieved.
3Productivity
If high extrusion speeds are used, then productivity increases, but deformation occurs due to gravity on the soft, plastic elastomer material
Solution Approach 1:
The base profile is vulcanized immediately after extrusion to convert it from a soft, plastic state to a dimensionally stable state. This preliminary vulcanization action allows high extrusion speeds to be used without deformation, as the material solidifies quickly after leaving the extruder.
Solution Approach 2:
The vulcanization process is performed rapidly immediately after extrusion, skipping the intermediate state where the material would be susceptible to gravitational deformation. This allows high productivity while maintaining precision.
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 reduces deformation, allows for higher extrusion speeds, and enhances the wiper's functionality by maintaining shape and performance, particularly by using thermoplastics that do not require vulcanization, thus avoiding thermal damage and corrosion, and providing improved durability and service life.
Implementation Method 1
providing better adhesion and dimensional stability
Implementation Method 2
the elastomer mass from which the squeegee and the carrier profile are formed is not yet crosslinked and is therefore soft and plastic
Data Source
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Figure 3
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AI summary
The invention relates to a method for producing extrudates comprising a first profiled section (1) made of an elastomer material and a second profiled section (13) that is connected to the first profiled section (1). In said method, the first profiled section (1) made of the elastomer material is first extruded and is then fully cured, whereupon a second profiled section (13) made of a thermoplastic material is extruded onto the first profiled section (1). The invention further relates to an extruded profiled element comprising a first profiled section (1) and a second profiled section (13) that is connected to the first profiled section (1). The first profiled section (1) is made of an elastomer material while the second profiled section (13) contains a thermoplastic material.