Impeller Blades With Pre-Shaped Tips Eliminating Internal Skeletons
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Solution Overview
Problem
Existing impeller blade manufacturing methods for complex shapes, such as airfoil designs, are labor-intensive and prone to erosion due to multiple welds and an internal skeleton, which increases weight and leads to uneven wear and flow discontinuities.
Innovation Solution
The impeller blades are constructed with a central hub and airfoil-shaped blades where the top and bottom skins are welded directly, eliminating the need for separate bar stocks and internal frameworks, with a cast tip that predesigns the outer contour, reducing erosion and simplifying the manufacturing process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If an internal skeleton with multiple bar stocks and welds is used to construct airfoil-shaped impeller blades, then structural strength and shape precision are improved, but device complexity and manufacturing labor intensity increase significantly
Solution Approach 1:
The invention removes the internal skeleton structure from the blade construction, extracting only the essential function of providing structural support. The skin itself is formed into the airfoil shape through bending and stretching, eliminating the need for internal bar stocks and framework while maintaining shape precision.
Solution Approach 2:
The invention merges the structural support function and the aerodynamic surface function into a single integrated skin structure. The skin is both the outer surface and the load-bearing element, eliminating the separation between skeleton and skin that characterized prior art constructions.
2Strength
If multiple welds and an internal skeleton are used in blade construction, then structural integrity is improved, but weight increases and erosion resistance decreases
Solution Approach 1:
The invention removes the internal skeleton and multiple welds from the construction, extracting only the essential welds needed to attach the skin to the hub. This eliminates the numerous weld joints that were prone to erosion in prior art designs.
Solution Approach 2:
The invention concentrates the welds in specific locations (at the hub interface) rather than distributing them along the entire blade length. The skin is formed as a continuous piece with local bending and stretching to create the airfoil shape, maintaining strength while minimizing exposed weld areas to erosive material flow.
3Manufacturing precision
If the tip is shaped by labor-intensive hand grinding after welding, then precise 3-D profile is achieved, but manufacturing time and cost increase
Solution Approach 1:
The tip profile is formed during the initial skin shaping process before the blade is assembled to the hub. The skin is bent and stretched to create the precise 3-D airfoil shape and rounded tip contour in advance, eliminating the need for subsequent hand grinding operations.
Solution Approach 2:
The tip shaping operation is merged with the skin forming operation. The same bending and stretching processes that create the airfoil shape also create the precise tip profile, eliminating the need for separate finishing operations.
4Strength
If bar stocks and internal framework are used to support the blade skins, then structural rigidity is improved, but overall blade weight increases
Solution Approach 1:
The invention removes the internal skeleton and bar stock framework from the blade construction, extracting only the essential function of supporting the skin at the hub interface. The skin itself provides the necessary rigidity through its airfoil shape and tension-compression structure.
Solution Approach 2:
The invention uses a thin skin that is formed into an airfoil shape through bending and stretching. The curved geometry and tension in the skin provide structural rigidity without requiring heavy internal support structures, achieving strength-to-weight optimization.
Data Source
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AI summary
A blade (15 ) for use in an impeller assembly comprising: a top skin element (20); a bottom skin element (22); and a unitary pre-shaped tip element (16) attached to the top and bottom skin elements without an internal framework and disposed at the radial outside end of the blade. A method of manufacturing a blade for an impeller assembly and an impeller assembly are also claimed.