Bolt-hole Cap Radial Protrusions Rail Alignment
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Solution Overview
Problem
Conventional bolt-hole caps for rail systems face issues with foreign object ingress, inadequate friction for secure positioning, and high manufacturing costs due to tight tolerances required for flush surface alignment, leading to reduced durability and increased manufacturing expenses.
Innovation Solution
A bolt-hole cap design featuring radially extending protrusions that undergo plastic deformation upon insertion, providing enhanced strength and frictional engagement with the bolt, eliminating the need for precise recesses and reducing manufacturing costs while maintaining flush alignment with the rail surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the bolt-hole cap diameter is slightly larger than the bolt hole diameter for friction-based positioning, then the cap can be easily installed, but the cap shifts when force is applied and cannot maintain secure positioning
Solution Approach 1:
The bolt-hole cap is segmented into multiple protrusions (typically 3-6) distributed around its circumference. Each protrusion independently engages with the bolt surface, distributing the positioning force across multiple contact points. This segmentation provides both easy installation (protrusions guide alignment) and secure positioning (multiple friction points resist shifting forces).
Solution Approach 2:
The protrusions create localized high-friction contact zones on the bolt surface. Instead of uniform friction across the entire cap perimeter, the protrusions concentrate frictional engagement at specific radial positions, enhancing positioning stability where needed while maintaining overall ease of installation.
2Reliability
If multiple rings are added to the bolt-hole cap outer periphery to enhance friction, then secure engagement is achieved, but the top surface becomes uneven after hammering
Solution Approach 1:
Instead of adding rings in the radial dimension (which creates height variations), the solution moves to the axial dimension by adding protrusions that extend downward toward the bolt. This dimensional shift provides engagement security through increased frictional contact area without compromising the top surface flushness, as the protrusions are positioned below the top surface level.
3Manufacturing precision
If tight tolerances are maintained for recess and cap alignment to ensure flush surfaces, then manufacturing precision is improved, but manufacturing cost increases significantly
Solution Approach 1:
The protrusions on the cap serve a dual function: they provide positioning stability through frictional engagement with the bolt, and they simultaneously guide the cap into proper alignment with the bolt hole during installation. This self-alignment feature eliminates the need for precisely machined recesses, allowing both the cap and rail to be manufactured with standard tolerances while still achieving flush surfaces.
Solution Approach 2:
The protrusions are pre-formed on the cap during cap manufacturing, creating built-in alignment features before installation. When the cap is pressed into the bolt hole, these pre-formed protrusions automatically engage with the bolt and guide the cap into the correct position, eliminating the need for subsequent alignment adjustments or precision recess machining.
4Reliability
If the protrusion distal end is deformed radially to contact the bolt, then space between cap and bolt is filled, but insufficient force causes further deformation and cap movement into the hole
Solution Approach 1:
The single protrusion is divided into multiple discrete protrusions (typically 3-6) around the cap circumference. Each protrusion independently contacts the bolt, distributing the sealing and support forces across multiple locations. This prevents any single protrusion from bearing excessive load that would cause it to deform and push the cap into the hole, while still effectively filling the space between cap and bolt.
Solution Approach 2:
The multiple protrusions act as distributed support elements that counterbalance applied loads. When force is applied to the cap, the protrusions collectively resist the force through frictional engagement with the bolt, preventing the cap from being pushed into the hole. The distributed nature of this counter-force prevents localized deformation that would occur with a single protrusion.
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 bolt-hole cap securely seals the bolt hole, prevents foreign object ingress, and maintains alignment with the rail surface, enhancing durability and reducing manufacturing costs through plastic deformation and increased frictional engagement.
Implementation Method 1
Each protrusion has two side faces and an end face connected between the two side faces. The end face has a first width. When the bolt-hole cap is inserted into a bolt hole, a pressing device is used to hit the bolt-hole cap, and a level block is used to keep the bolt-hole cap in horizontal position, so that the top face of the bolt-hole cap is in flush with the top face of the rail. The end face of the at least one protrusion contacts the bolt in the bolt hole and the at least one protrusion is plastically deformed toward the side faces and the end face is deformed to have a second width which is wider than the first width.
Implementation Method 2
the at least one protrusion is plastically deformed toward the side faces and the end face is deformed to have a second width which is wider than the first width. Even an extra external force is exerted on the bolt-hole cap, the bolt-hole cap does not move into the bolt hole or tilt by the deformed protrusion between the bolt and the bolt-hole cap.
Data Source
AI summary
A bolt-hole cap for sealing the bolt hole of a rail includes a top face and a bottom face from which multiple protrusions extend. Each protrusion extends radially from inner portion toward outer portion of the bolt-hole cap. Each protrusion has two side faces and an end face connected between the two side faces. The end face has a first width. When the bolt-hole cap is inserted into a bolt hole and the top face of the bolt-hole cap is in flush with the top face of the rail, the end face of each of the protrusions contacts the bolt in the bolt hole. The protrusions are plastically deformed toward the side faces and the end face has a second width which is wider than the first width, so that the bolt-hole cap has sufficient strength to keep the top thereof flushing the top of the rail.