Weld Location Strategy for Mixing Impeller Blades
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Solution Overview
Problem
Existing impeller blade construction methods for mixing devices are complex, 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, especially when handling abrasive materials.
Innovation Solution
The impeller blade design eliminates the need for internal skeletons and separate bar stocks by welding a pre-shaped top and bottom skin directly, with the weld areas tucked under the blade edges to reduce erosion, and uses a cast tip that can be predesigned and mounted without manual finishing, reducing labor and improving smoothness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If an internal skeleton with multiple bar stocks and welds is used to construct air foil shaped impeller blades, then the structural strength and shape accuracy are improved, but the device complexity and manufacturing labor increase significantly
Solution Approach 1:
The patent removes the internal skeleton and intermediate bar stocks from the traditional construction method. Instead of using multiple separate components (front bar stock, rear bar stock, interior skeleton, top skin, bottom skin), the invention uses a single monolithic piece of bar stock that is directly formed into the air foil shape and welded to the hub, eliminating unnecessary structural elements while maintaining strength.
Solution Approach 2:
The patent combines multiple separate components into a single integrated structure. The front bar stock, rear bar stock, and interior skeleton are merged into one continuous piece of bar stock that is directly formed into the air foil shape. This consolidation reduces the number of welds from four or more to a single weld at the hub connection point.
2Strength
If multiple welds are used to attach bar stocks and skins at leading and trailing edges, then the structural integrity is improved, but the erosion resistance deteriorates due to material wear discontinuity at weld locations
Solution Approach 1:
The patent removes the multiple weld connections at the leading and trailing edges by eliminating the separate bar stocks and interior skeleton that required these welds. The single monolithic bar stock structure eliminates the weld discontinuities that create erosion-prone zones, leaving only the hub weld which is positioned to minimize erosion exposure.
3Manufacturing precision
If the tip piece is shaped by labor intensive hand grinding after welding, then the complex 3-D profile accuracy is improved, but the manufacturing productivity decreases
Solution Approach 1:
The patent performs the shaping action during the manufacturing process itself rather than as a post-processing step. The monolithic bar stock is directly formed or machined into the final air foil shape with the correct tip profile before being welded to the hub. This eliminates the need for subsequent hand grinding and shaping operations, achieving both high precision and high productivity.
Data Source
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AI summary
A blade (15) having a leading edge (30) and a trailing edge (32), for use in an impeller assembly comprising: a top skin element (20) a bottom skin element (22) a first weld joint (24) attaching the top skin element directly to the bottom skin element proximate the leading edge (30) of the blade, and a second weld joint (26) attaching the top skin element to the bottom skin element proximate a trailing edge (32) of the blade. A method of forming a blade, having a leading edge and a trailing edge, for use in an impeller assembly is also claimed.