Push-Fit Sheet Metal Duct Assembly With Resilient Locking Catches
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Solution Overview
Problem
The existing methods for fabricating and assembling ducting systems are costly due to expensive handling and forming processes in workshops, high storage and shipping costs, and complex on-site handling, especially for large duct cross-sections.
Innovation Solution
A tubular duct member is created by joining circumferential sheet metal panels with cooperating folded sheet metal catches that engage with detent surfaces, using resilient material to maintain the connection and provide structural rigidity, allowing for push-fit assembly and reducing the need for separate joint fabrication.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If ducting is fabricated and assembled in a workshop using machines such as guillotines, press brakes and seamers, then manufacturing precision and reliability are improved, but handling and forming costs increase
Solution Approach 1:
The ducting system is divided into modular panels with standardized catches, allowing pre-fabrication in workshop conditions while enabling simple on-site assembly. Each panel is an independent unit that can be manufactured with high precision using workshop equipment, then transported and assembled without requiring the same level of equipment at the installation site.
Solution Approach 2:
The catches are pre-formed as integral parts of each panel during manufacturing, so that the complex forming operations are completed in advance at the workshop. This preliminary action eliminates the need for on-site forming equipment and reduces handling costs, as panels arrive ready for simple push-fit assembly.
2Productivity
If large duct cross sections are used, then air and gas distribution capacity is improved, but storage, handling and shipping costs increase
Solution Approach 1:
Large duct cross-sections are achieved by assembling multiple smaller panels together using the catch system. Each panel can be manufactured and stored at a manageable size, but when assembled on-site, they form large-diameter ducting with high distribution capacity. This segmentation allows efficient storage and shipping of individual panels while achieving large-scale performance in the finished installation.
3Device complexity
If panels are joined by pushing male members into female members without resilient material, then device complexity is reduced, but joint reliability and airtightness deteriorate
Solution Approach 1:
A resilient material acts as an intermediary between the male and female catches, filling gaps and ensuring airtight sealing. The resilient material deforms to accommodate manufacturing tolerances and installation variations, maintaining reliable sealing without requiring complex adjustment mechanisms or precision machining.
Solution Approach 2:
The resilient material changes its physical parameters (compression, deformation) during assembly to create the seal. When the male catch is pushed into the female catch, the resilient material compresses and deforms to fill the joint space, creating an airtight seal that adapts to variations in manufacturing tolerances and installation conditions.
4Manufacturing precision
If multiple separate joint components are used to connect panels, then ease of assembly is reduced, but manufacturing precision can be maintained
Solution Approach 1:
The catch is designed as an integral, folded portion of each panel rather than a separate component. This merging of the joining mechanism into the panel structure itself maintains manufacturing precision (as the catch is formed with the panel in a single operation) while dramatically simplifying assembly (as no separate joint components need to be handled or installed).
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 approach reduces manufacturing, storage, and shipping costs by enabling mass production of pre-assembled panels that can be easily assembled on-site, minimizing handling and transportation expenses while providing a durable and airtight conduit.
Implementation Method 1
at least one of the catches includes a body of resilient material compressed between the catches and biasing the catches apart to maintain the detent surfaces bearing against one another
Data Source
AI summary
A tubular duct member comprises a plurality of sheet metal panels 10, 12 joined along adjacent longitudinal edges by cooperating folded sheet metal catches 14, 16, the catches being pushed together such that respective detent surfaces 28, 30 on each catch engage behind one another to retain the edges of the sheets together. One of the catches 14 includes a body 36 of resilient material compressed between the catches and biasing the catches apart to maintain the detent surfaces 28, 30 bearing against one another.