High-Head Francis Runner External Welding for Confined-Space Safety
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Solution Overview
Problem
Manufacturing high head Francis runners is challenging due to the need for difficult operations like welding and grinding within narrow spaces, posing health and safety risks and requiring specialized skills that are becoming scarce.
Innovation Solution
The method involves assembling blades and a crown, then welding metal plates between neighboring blades from the outside to form the band, with welding beads visible from the outside, allowing operations to be performed safely and efficiently without entering the runner interior.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If welding operations are performed inside the runner to assemble blades and band, then the runner can be manufactured with tight tolerances and proper structural integrity, but operator safety deteriorates and specialized skills become increasingly difficult to find
Solution Approach 1:
The patent inverts the conventional welding approach by performing welding operations from the outside of the runner rather than from the inside. The band is divided into segments that are welded to the external surfaces of adjacent blades, allowing operators to access weld joints from the runner's outer perimeter. This inversion maintains structural integrity while eliminating the need for operators to work in confined internal spaces.
Solution Approach 2:
The band is segmented into multiple sections that can be independently positioned and welded to blade surfaces. This segmentation allows the band to be assembled in stages from the outside, with each segment accessible for welding operations. The segmented approach enables proper structural connection while facilitating safe external assembly operations.
2Manufacturing precision
If operators enter the hydraulic passages of the runner to perform welding and grinding operations, then the runner can be manufactured with proper precision, but health and safety issues arise
Solution Approach 1:
The patent reverses the conventional approach by performing all welding and grinding operations from the outside of the runner. Weld joints are positioned on external surfaces of blades and the band, allowing operators to access all necessary surfaces without entering hydraulic passages. This maintains manufacturing precision while eliminating health and safety risks associated with confined space work.
Solution Approach 2:
The patent extracts the welding and grinding operations from the internal hydraulic passages and relocates them to external surfaces. By positioning all weld joints and grinding surfaces on the outer perimeter of the runner, the harmful practice of entering confined spaces is completely eliminated while precision manufacturing is preserved through external access to all critical surfaces.
3Ease of manufacture
If the band is split into segments to allow operator access, then manufacturing becomes more accessible, but the structural complexity and number of weld joints increases
Solution Approach 1:
The band is divided into a reasonable number of segments that balance accessibility with structural simplicity. Each segment is sized to allow external welding operations while minimizing the total number of joints. The segmentation is optimized so that operators can access all weld locations from the runner's outside without requiring excessive divisions that would complicate the structure.
Solution Approach 2:
The patent uses external positioning of band segments rather than internal access methods. By designing the segmentation and weld joint locations so that all connections can be made from the outside, the need for complex internal access mechanisms is eliminated. The segmentation strategy is optimized for external assembly, reducing overall complexity compared to alternative approaches.
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 enables safe and efficient manufacturing of high head Francis runners by eliminating the need for dangerous interior welding and grinding, reducing health risks and skill dependency.
Implementation Method 1
welding metal plates between neighboring blades from the outside to form the band
Data Source
Figure 1~2A
Figure 2B~3A
Figure 3B~3C
AI summary
The invention relates to a method for assembling a high head Francis runner comprising a crown, a band and blades extending between said crown and said band, said method comprising: - assembling the blades (8) and the crown (6); - then welding from outside the runner a plurality of metal plates (10) between each two neighbouring blades, the end (8a) of the blades and the plurality of metal plates thus forming the band.