Conical Screw Anchor for Rail Fastening Lateral Force
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Solution Overview
Problem
Conventional screw anchors for railway sleepers and slab tracks fail to transmit sufficiently high lateral forces from rail fastenings to the sleeper or track.
Innovation Solution
A screw anchor with a conical outer section and a trapezoidal internal thread, along with external round threads, designed to increase the contact surface area and enhance force transmission, and ribs to prevent twisting, allowing for improved lateral force transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If conventional screw anchors with cylindrical shape are used, then the structure is simple and easy to manufacture, but the lateral force transmission capability is insufficient
Solution Approach 1:
The screw anchor is divided into two distinct sections: a first section with cylindrical outer shape and a second section with conical outer shape. This segmentation allows each section to serve different functions - the cylindrical section provides structural simplicity while the conical section enhances lateral force transmission through increased contact surface area with the surrounding concrete.
Solution Approach 2:
The conical outer shape is applied locally to the second section of the screw anchor, specifically in the region where lateral force transmission is most critical. This localized geometric modification increases the contact surface area between the anchor and surrounding concrete without requiring the entire anchor to be complex, thus improving lateral force capability while maintaining reasonable structural simplicity.
2Force
If the contact surface area between anchor and sleeper is increased, then lateral force transmission is improved, but the surface pressure increases
Solution Approach 1:
The conical outer shape introduces a dimensional change from a uniform cylindrical form to a tapered geometry. This dimensional modification increases the contact surface area distributed over a larger volume of surrounding concrete, thereby improving lateral force transmission while the increased distribution area helps manage surface pressure through better stress distribution.
3Reliability
If the screw anchor is made of plastic material, then electrical insulation is achieved, but the tear-out strength and long-term stability are reduced
Solution Approach 1:
The screw anchor utilizes plastic material composition that combines electrical insulation properties with enhanced mechanical strength. The plastic material is formulated to provide both the required electrical insulation for railway applications and sufficient tear-out strength for reliable fastening, creating a composite material solution that addresses both requirements simultaneously.
Data Source
Figure 1~2
Figure 3~4
AI summary
A screw anchor for embedding in a railway sleeper or slab track comprises external threads (16) arranged on the outside of the screw anchor (10) and internal threads (18) arranged inside the screw anchor (10) for a force-fit connection with a fastening element (30), wherein the screw anchor (10) consists of two longitudinally adjacent sections (12, 14), the first section (12) having a substantially cylindrical outer shape and the second section (14) having a substantially conical outer shape, and wherein the second section (14) is arranged between the first section (12) and an insertion opening (26) for the fastening element (30).