Fusion Welding Large Plastic Tanks Using Pre-secured Elements
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Solution Overview
Problem
The challenge lies in manufacturing large plastic tanks that are economically viable, easily shippable, and can be reliably assembled using modestly skilled labor, while ensuring they are strong and liquid-tight, as existing methods are costly and inefficient due to the need for large molds and limited assembly capabilities at remote sites.
Innovation Solution
The solution involves forming large thermoplastic tanks by fusion welding half-shell parts into tubular bodies and attaching end caps, using fusion weld elements that are pre-secured to the parts and activated by electric or electromagnetic energy for on-site assembly, allowing for compact shipping and assembly into finished products.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If large plastic tanks are made by blow molding or rotational molding, then production rate is high, but molds are large and costly
Solution Approach 1:
The tank is divided into multiple modular sections that can be manufactured separately using standard injection molding equipment and then assembled on-site. Each section is a self-contained unit with standardized connection interfaces, allowing the tank to be built from smaller, more manageable components rather than requiring one large complex mold.
Solution Approach 2:
Connection elements such as protrusions and recesses are pre-formed as integral parts of each tank section during injection molding. These pre-formed connection features enable straightforward assembly at the site without requiring additional complex molding operations or specialized equipment.
2Quantity of substance
If tanks are made as multi-piece assemblies, then shipping costs are reduced, but assembly reliability becomes difficult to ensure
Solution Approach 1:
The connection between tank sections is achieved through fusion welding of thermoplastic materials using heat, replacing traditional mechanical fastening systems. This fusion process creates a molecular-level bond between sections, eliminating the need for bolts, clips, or other mechanical connectors that would require additional sealing components and assembly precision.
Solution Approach 2:
The thermoplastic connection elements undergo phase transition from solid to molten state during welding, allowing the sections to fuse together. The heat applied during assembly temporarily softens the thermoplastic material at the connection interfaces, enabling the sections to bond permanently as the material cools and solidifies.
3Manufacturing precision
If injection molding is used to manufacture tank parts, then dimensional control is improved, but manufacturing equipment cost increases
Solution Approach 1:
The tank is divided into multiple modular sections that can be manufactured separately using standard injection molding equipment and then assembled on-site. Each section is a self-contained unit with standardized connection interfaces, allowing the tank to be built from smaller, more manageable components rather than requiring one large complex mold.
Solution Approach 2:
The same standardized connection interfaces and thermoplastic materials are used across all tank sections, allowing a single set of injection molding tools and processes to manufacture multiple identical or varied section types. This universality reduces the need for specialized expensive equipment for each section variation.
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 method enables the cost-effective production and assembly of large plastic tanks, reducing shipping and storage costs while ensuring reliable and strong liquid-tight seals, even at remote sites with limited equipment, by using pre-secured fusion weld elements for efficient on-site welding.
Implementation Method 1
Electric or electromagnetic energy is used to melt in situ the fusion weld element, to make a weld and form a tubular body with open ends
Implementation Method 2
Electric or electromagnetic energy is used to melt in situ the fusion weld element
Data Source
AI summary
A large tubular plastic tank is formed by fusion welding together half-shell parts at lengthwise flange joints to form a tubular body. Then, end caps are fusion welded onto the outermost ends of the tubular body and an assembly of two or more bodies. Electric or electromagnetic energy is used to melt in situ the fusion weld elements which are captured between the joining surfaces of the parts. A fusion weld element is secured beforehand to linear a joining surface of at least one of two mated tank parts. The weld element exits the joint between two lengthwise-mated parts at the location of mating tabs extending from the mated tank parts; the tabs are subsequently cut away. A circumferential flange joint is made by securing a fusion weld element to at least one joining surface of the mated tank parts, where the ends of the element run through holes in the faying surface of the flange.