Plastic Fastener Head Formation via Surface Tension
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Solution Overview
Problem
Existing methods for producing adhesive fastening elements, such as touch fasteners, face challenges including limited adhesion forces due to small head dimensions, high plastic scrap rates, and complex production processes with multiple molds, which increase costs and reduce efficiency.
Innovation Solution
A method and device that form head parts independently through surface tension of the plastic material, eliminating the need for expensive molding tools and using only two molding tools: a stationary tool for the support part and a lost mold for the stem parts, allowing for efficient production and cost reduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If head parts are formed from plastic material in a molding tool, then adhesion forces are improved, but head parts become smaller due to low material charging
Solution Approach 1:
The plastic material forms the head parts independently through surface tension during the molding process, without requiring a separate molding tool for the head parts. The material self-organizes into the desired head shape as it is extruded through the stem parts, eliminating the constraint of fixed mold cavities and allowing for larger head dimensions with adequate material charging.
2Manufacturing precision
If a doctor blade is used to remove excess plastic material, then head part dimensions are controlled, but plastic scrap increases
Solution Approach 1:
The plastic material self-regulates its flow and shaping through surface tension forces during extrusion, forming the head parts without requiring a doctor blade to remove excess material. The material naturally forms the desired shape as it is pushed through the molding tool, eliminating the need for mechanical removal of excess plastic and thereby reducing scrap.
Solution Approach 2:
The invention changes the physical parameters of the plastic material during the molding process, specifically utilizing surface tension effects to control the shaping of head parts. By adjusting parameters such as extrusion speed, material temperature, and mold geometry, the material self-forms the head parts with precise dimensions without requiring post-molding material removal.
3Manufacturing precision
If multiple molding tools are used for support part and head parts, then production precision is improved, but device complexity increases
Solution Approach 1:
The invention combines the molding of support parts and head parts into a single integrated process using one molding tool. The molding tool contains cavities that simultaneously form both the support part and the head parts in one operation, eliminating the need for separate molding tools and reducing device complexity while maintaining production precision through proper tool design.
Solution Approach 2:
The single molding tool is designed to perform multiple functions: it molds both the support part and the head parts, and it controls the extrusion of plastic material through the stem parts. This multi-functional tool eliminates the need for multiple specialized molding tools while maintaining the precision required for producing accurate fastener elements.
4Volume of moving object
If hook-shaped mold recesses are used, then large touch fastener elements are produced, but mold removal becomes difficult
Solution Approach 1:
The invention segments the molding process into two distinct stages: first molding the support part, then separately molding the stem parts with head parts. The molding tool is removed after the support part is molded, and stem parts are molded in a separate step. This segmentation allows for easy mold removal while still producing large fastener elements, as the tool geometry is not constrained by the final fastener shape.
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 the production of reliable touch fastener elements with adjustable fastening behavior at lower costs, using demanding materials like acrylate and thermoplastics, and simplifies the production process by reducing the number of molds and handling efforts, resulting in a more efficient and economical manufacturing process.
Implementation Method 1
the head parts of the touch fastener element are formed free of a molding tool as a result of the surface tension of the plastic material used
Data Source
AI summary
A method for producing an adhesive fastening element made of plastic includes a support part (10) from which project a plurality of stem parts (12). A head part (14) is arranged at each stem part opposing the support part (10) and the head parts (14) are formed without the use of molding tools due to the surface tension of the used plastic material. Consequently, no need exists for a specific molding tool for forming the head parts.