Frangible Dowel Cradle Linking Device for Concrete Slabs
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Solution Overview
Problem
The existing dowel cradle designs require costly and time-consuming welding of a metallic bar for linking longitudinal members, which poses safety hazards and can cause unwanted cracking in concrete slabs if not properly cut after embedding.
Innovation Solution
A clip-on frangible travel bar made of polypropylene with resilient clips and gripping ribs, designed to clip onto the dowel cradle members without welding, featuring a frangible portion that breaks under tension to allow for free movement and prevent cracking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a metallic bar is welded onto the dowel cradle to link longitudinal members, then the rigidity of the apparatus during transportation is improved, but the manufacturing cost and manufacturing time increase
Solution Approach 1:
The patent replaces the welding process with a friction-based mechanical connection system. A friction bar with a friction surface is inserted into a corresponding friction groove, creating a rigid connection through friction forces rather than thermal welding. This substitution eliminates welding costs and time while achieving the same rigidity function.
Solution Approach 2:
The patent changes the connection method from permanent welding to a reversible friction-based mechanical connection. The friction bar can be inserted and removed without damaging the components, allowing for easy assembly and disassembly, thereby reducing manufacturing time and cost while maintaining rigidity during transport.
2Strength
If a metallic bar is welded onto the dowel cradle, then the rigidity during transportation is improved, but safety hazards arise from protruding edges
Solution Approach 1:
The patent replaces welding with a friction-based mechanical insertion system where the friction bar fits into a groove. This eliminates the need for post-welding grinding or trimming operations that often result in protruding edges, thereby eliminating the safety hazard while maintaining the rigidity function.
3Strength
If the metallic bar is left uncut after embedding, then the dowel cradle maintains rigidity, but unwanted parallel cracking occurs in concrete slabs
Solution Approach 1:
The patent creates a dynamic connection system where the friction bar can transition from a rigid state during transport to a flexible state after embedding. The friction-based connection allows the bar to be easily removed or cut after the concrete has set, preventing the transmission of stresses that would cause parallel cracking while maintaining rigidity during the critical transport phase.
Solution Approach 2:
The friction bar is designed as a separate, removable component rather than a permanent welded structure. This segmentation allows the bar to be easily removed after embedding, separating the transport function from the final embedded state, thereby preventing harmful cracking while maintaining rigidity during transport.
4Ease of manufacture
If manual welding is used to attach the metallic bar, then the longitudinal members are linked, but the process is time-consuming and requires skilled labor
Solution Approach 1:
The patent replaces manual welding with a simple friction-based insertion process. The friction bar is inserted into the friction groove and secured through friction forces, eliminating the need for skilled welders and lengthy welding procedures. This mechanical substitution dramatically reduces manufacturing time and labor skill requirements.
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
This solution reduces manufacturing costs and safety risks by eliminating the need for welding, ensuring the dowel cradle's rigidity during transport and allowing for easy attachment and detachment, while preventing parallel cracking in concrete slabs.
Implementation Method 1
the length of bar including a frangible portion which is configured to stretch or break under tension applied in a longitudinal direction of the bar
Implementation Method 2
the clipping components take the form of resilient clips
Implementation Method 3
The bar is provided with a plurality of gripping ribs
Data Source
Figure 1~2
Figure 3~4
Figure 5
AI summary
A device (11) for linking separate members of a dowel cradle, comprising: a bar (12); and at least two couplings (13, 14), located on the bar. A dowel cradle comprising: at least one load transfer dowel; a basket having a pair of elongate members (31, 32) spaced apart from each other to support the load transfer dowel thereon; a device (11) comprising: a bar (12) located between the two elongate members of the basket; and at least two couplings (13, 14) located on the bar, each coupling being attached to a respective one of the elongate members of the basket.