Plastic Dowel with 90-Degree Projections for Rail Fastening
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Solution Overview
Problem
Plastic dowels used in rail fastening systems often cause near-surface cracks in concrete substrates due to stress peaks from threaded connections, leading to potential destruction of the substrate.
Innovation Solution
The design of the plastic dowel features a holding section with projections or threads aligned at a 90° angle to the longitudinal axis, minimizing transverse forces and stress peaks by distributing loads more uniformly, and incorporating a second holding section with a rounded transition to reduce stress concentrations and enhance anchoring.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If threaded connections are used in the holding section for fastening the rail screw, then the anchoring strength and load-bearing capacity are improved, but stress peaks occur in the surrounding substrate material leading to crack formation
Solution Approach 1:
The holding section is divided into multiple threaded projections distributed around the circumference, rather than a single continuous thread. This segmentation distributes the stress peaks across multiple discrete contact points, reducing the concentration of stresses in any single location and thereby minimizing crack formation in the surrounding substrate while maintaining overall anchoring strength.
Solution Approach 2:
The threaded projections are designed with specific geometric characteristics (thread angle, pitch, depth) that optimize the distribution of stresses locally at each projection while considering the global anchoring requirement. The local thread geometry is tailored to reduce stress concentration in the substrate, creating a transition from high-stress concentrated threading to a more uniform stress distribution pattern.
2Reliability
If projections or threads are added to the holding section for better anchoring, then the anchoring security is enhanced, but the complexity of the dowel structure increases
Solution Approach 1:
The dowel integrates multiple functions into a single component: the holding section simultaneously provides anchoring through threaded projections, structural support through the cylindrical body, and electrical insulation through the plastic material. This merging eliminates the need for separate anchoring elements, reducing overall system complexity while maintaining high anchoring security.
Solution Approach 2:
The plastic dowel is designed as a universal fastening element that combines mechanical anchoring (threaded projections), structural support (cylindrical shank), and electrical insulation (plastic material) in one component. This multi-functionality allows the same dowel design to be used across different fastening applications, reducing the variety of components needed and simplifying the overall system.
Data Source
AI summary
The present invention relates to a plastic dowel for the fastening of a rail on a solid substrate. The plastic dowel includes an opening, an interior, a shank section, and a holding section, which provides at least one circumferential projection around its circumference. The at least one projection protrudes in a radial direction whereby the upper flank of the projection of the holding section assigned to the dowel opening is aligned at an angle of 90°±3° in relation to a longitudinal axis of the plastic dowel.