Shear Bolt Head Geometry for Accessible Removal
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Solution Overview
Problem
Existing shear bolts used in bollards often shear off at poorly accessible points within the base, making it difficult and time-consuming to remove the threaded shanks after shearing, requiring laborious drilling when the protruding shank cannot be gripped with pliers.
Innovation Solution
A shear bolt with a special geometry featuring a predetermined breaking point, where the head is designed with a driving profile that extends into the threaded shank, allowing easy removal of the sheared-off bolt using a tool, ensuring the bolt can be unscrewed from the recess even after breaking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If shear bolts are made with predetermined breaking points to enable clean separation of the standpipe from the anchor plate, then the reliability of the bollard system is improved, but the ease of removing the sheared bolts deteriorates when they break within the base recesses
Solution Approach 1:
The patent applies preliminary action by pre-forming a breaking groove that guides the shear bolt to break at a specific location with a protruding end. This predetermined breaking pattern ensures that when the bolt shears, a portion of the threaded shank remains accessible outside the base, allowing for easy removal with standard tools like pliers, thus resolving the contradiction between reliable separation and easy removal
2Loss of substance
If shear bolts are designed to shear off cleanly to prevent damage to anchor plate and base, then the loss of substance is reduced, but the time required for restoration increases due to difficulty in removing the sheared bolts
Solution Approach 1:
The breaking groove is pre-formed during manufacturing to control the shear location. This ensures clean separation that prevents damage to the anchor plate and base while simultaneously ensuring that a protruding end of the threaded shank remains accessible for quick removal with standard tools, thereby reducing both material loss and restoration time
3Manufacturing precision
If optimization of predetermined shear grooves is performed to control breaking location, then the manufacturing precision is improved, but the shear bolts still break at poorly accessible points within the base
Solution Approach 1:
The breaking groove is strategically designed during manufacturing to control the shear location while ensuring the break occurs in a position where a protruding end of the threaded shank extends beyond the base surface. This preliminary design ensures both precise breaking location control and accessibility for tool engagement, resolving the contradiction between manufacturing precision and operational accessibility
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
Enables efficient removal of sheared shear bolts without damaging the bollard components, allowing for quick restoration of the bollard by preventing damage to the anchor plate and base, and facilitating easy replacement of shear bolts.
Implementation Method 1
Under increased force, such as from contact with a vehicle, the shear bolts are sheared off by tilting the standpipe and base relative to the anchor plate
Data Source
Figure 1a~1b
Figure 2a~2c
Figure 3a~3b
AI summary
The shear screw (3) has a head (30) with a driver profile (33), and a threaded shaft with an outer thread (320), where the shear screw has a predetermined breaking point on the head or the threaded shaft. The end of the driver profile reaches to the area of the threaded shaft, in which the thread pitch of the external thread lies. A predetermined breaking point area (31) is formed, which is penetrated by the driver profile in longitudinal direction. An independent claim is included for a barrier post with an anchor plate.