Tapered Spiral Welded Cone Geometry for On-Site Tower Fabrication
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Solution Overview
Problem
Current spiral welding technologies are unable to produce large diameter conical structures efficiently on-site due to deformation issues and impracticality for forming large structures like wind turbine towers, as existing methods require in-plane deformation or mandrels that are not feasible for large-scale applications.
Innovation Solution
A method for forming a tapered spiral welded conical structure by graphically unwrapping the cone shape and creating construction arcs and lines to define the strip geometry, allowing it to be wrapped and edge-butt welded without in-plane deformation, using various strip shapes such as constant width, stepped, or logarithmic spirals, with equations provided for determining the strip geometry to achieve multiple wraps and large diameters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If existing spiral welding technology is used to form conical structures, then welding can be performed, but the metal stock undergoes significant deformation that is impractical to achieve on site
Solution Approach 1:
The strip is pre-formed with a specific curved geometry (logarithmic spiral or constant width with curved edges) before welding, so that when wrapped around the mandrel it naturally forms the conical structure without requiring deformation during the welding process itself. This preliminary shaping allows on-site fabrication while maintaining geometric precision.
Solution Approach 2:
The invention changes the geometric parameters of the strip (width, curvature, edge shape) to match the required conical surface geometry. By carefully designing the strip parameters beforehand, the wrapping process becomes a simple geometric transformation rather than a deformation process, enabling on-site manufacturing.
2Shape
If a mandrel is used to form large diameter conical structures, then the conical shape can be achieved, but providing a mandrel for very large structures such as wind turbine towers is not feasible
Solution Approach 1:
The invention extracts the mandrel from the final structure by designing the strip geometry so that it forms the conical shape through wrapping alone. The mandrel serves only as a temporary form during wrapping and is not part of the final structure, making it feasible for very large diameters where traditional fixed mandrels would be impractical.
Solution Approach 2:
The strip acts as a flexible shell that can be wrapped around large diameters without requiring a rigid mandrel. The flexibility of the strip allows it to conform to large conical surfaces, enabling the formation of very large structures like wind turbine towers without the complexity of providing support mandrels throughout the entire structure.
3Length of moving object
If traditional tower designs are used that are transported to site and bolted together, then transportation is feasible, but the structures are heavier for the same or greater height
Solution Approach 1:
The tower is preliminarily formed as a continuous welded structure on-site rather than being transported as separate sections. This eliminates the need for heavy bolting connections and reduces overall weight, while the on-site welding process allows for optimized material usage and continuous structural integrity.
4Ease of operation
If the strip width is constant, then material handling is simplified, but the helix angle changes as the strip is wound which causes the edges to spread apart
Solution Approach 1:
The invention introduces asymmetry in the strip design by using either a logarithmic spiral shape or a constant width strip with curved edges. This asymmetric geometry compensates for the changing helix angle during wrapping, ensuring that the edges remain aligned and can be properly welded despite the varying wrap angle throughout the conical structure.
Data Source
AI summary
A method for creating a tapered spiral welded conical structure where the overall shape of the cone is first graphically slit axially and unwrapped, and then a series of construction arcs and lines are created to form the edge lines of a strip that can then be wrapped (rolled) to form a tapered conical structure. The edges of the spirally wound strip can be welded together, and a very large conical structure can thus be achieved. Various construction options are presented from a constant width strip to strip made from straight segments. Equations are given for the formation of the strips to enable those skilled in the art of spiral welded tubing to practice the invention.