Wedge Anchor Bolt Removal via Screw Step Mechanism
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Solution Overview
Problem
Low cost wedge anchor bolts are difficult to remove once tightened due to the cage and wedge becoming stuck in the hole, lacking a mechanism for easy separation, which is a limitation compared to more expensive expansion type anchor bolts.
Innovation Solution
Incorporating a screw with depressed or projecting portions that create a step for interference contact with the cage, allowing the wedge to be forcibly ejected from the cavity by continuing to withdraw threads while stopping axial translation, enabling the bolt to be removed without leaving the cage and wedge behind.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a basic wedge anchor bolt is used to maintain low cost, then manufacturing cost is reduced, but ease of removal deteriorates because the cage and wedge become stuck in the hole
Solution Approach 1:
The invention segments the anchor bolt system into distinct functional components: a screw member with threaded shank, a wedge member with internal threads, and a cage member with a cavity. This segmentation allows the wedge to be independently ejected from the cavity through the step mechanism, enabling easy removal while maintaining the simple, low-cost basic wedge anchor bolt design without requiring complex integrated mechanisms.
2Ease of operation
If expansion type anchor bolts are used to achieve easy removal, then ease of removal is improved, but manufacturing cost increases significantly
Solution Approach 1:
The invention extracts the removal mechanism from the complex expansion type anchor bolt system and implements it as a simple step feature on the screw member that works with the cage member. This step feature, combined with the threaded wedge, provides the ejection function without requiring expensive components like spring-biased wedges, slidable bushings, or hammering mechanisms, thereby maintaining low manufacturing cost while achieving easy removal.
3Ease of operation
If the cage and wedge are left in the hole after removing the screw, then complete removal is prevented, but additional drilling steps are required
Solution Approach 1:
The invention merges the ejection function into the existing screw member by adding a simple step feature. When the threaded shank is withdrawn from the wedge, the step engages with the cage's step-engaging portion, automatically ejecting the wedge from the cavity. This integration ensures complete removal of all components (screw, cage, and wedge) as a single unit without requiring separate drilling operations or additional removal steps.
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 easy and complete removal of the wedge anchor bolt without additional drilling, maintaining cost competitiveness while ensuring structural integrity by preventing corrosion and facilitating safe removal after service life is over.
Implementation Method 1
The shank 4b has a threaded end for engaging the internal threads of a wedge 8 at the distal end of the shank. Turning the screw 4 in one direction, typically clockwise, threads the shank 4b further into the wedge 8, drawing the wedge into the cage 6 and thereby causing the cage to expand.
Implementation Method 2
The wedge member is shaped in cooperation with the cavity to force the cavity to undergo a radial expansion as a result of being drawn into the cavity by means of advancing the threads of the threaded shank, the wedge member becoming stuck in the cavity as a result.
Implementation Method 3
Continuing to turn the screw in the same direction eventually results in the cage 6 being expanded sufficiently tightly against the interior surface(s) of the hole to result in a frictional anchoring of the insertion portion 9 therein.
Data Source
AI summary
A wedge anchor bolt having a screw member, a wedge member, and a cage member. The bolt is anchored into a drilled hole by wedging the wedge member in the end of the cage member by turning the screw member, with the result being that the wedge member becomes stuck in the cage member. For ejecting the wedge member from the cavity the screw member includes at least one of (1) one or more depressed portions, and (2) one or more projecting portions, defining a step, and the cage member includes one or more corresponding step-engaging portions for making an interference contact with the step, so that further withdrawal of the threads ceases to withdraw the threads relative to the cage member while continuing to withdraw the threads relative to the wedge member, thereby forcing the wedge member distally relative to the cavity.