Seat Ring Volute Split Assembly Without Transition Joint Sections

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Solution Overview

Problem

The existing manufacturing process for stay ring and spiral case assemblies in pumped storage units involves multiple non-value-added operations, difficulty in ensuring dimensional accuracy, significant welding stress, and lengthy manufacturing cycles due to the 'split surface transition plate + joint section' structure, which complicates assembly and adjustment.

Innovation Solution

The method involves cutting and forming spiral case sections in one piece, welding and annealing them in the factory, and then cutting along split surfaces to form split segments, which are transported and assembled with a circumferential weld at the construction site, eliminating the traditional 'transition plate + joint section' structure.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If the traditional 'transition plate + joint section' structure is used, then the assembly can accommodate dimensional tolerances, but the manufacturing process becomes complex with multiple non-value-added operations

Engineering Contradiction:
Improvedimensional accuracy of end surfacesVSAvoidmanufacturing process complexity
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent removes the transition plate and joint section from the assembly, extracting the problematic components that caused manufacturing complexity. The spiral case is directly connected to the stay ring through a simplified interface, eliminating the need for separate transition components and reducing the number of welding operations.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent merges the transition function directly into the spiral case structure by integrating the water guide mechanism with the spiral case body. This combines multiple functions into a single unified structure, eliminating the need for separate transition plates and joint sections.

Inventive Principle:
Principle #5Merging (Combining)

2Manufacturing precision

If the joint section is prepared and adjusted with both end surfaces processed, then dimensional accuracy is ensured, but significant time is consumed for workpiece repositioning and processing

Engineering Contradiction:
Improvedimensional accuracy of joint section end surfacesVSAvoidprocessing time for workpiece repositioning
Core Design Contradiction:
Manufacturing precisionVSLoss of time

Solution Approach 1:

The patent performs preliminary positioning and processing of the spiral case sections during factory manufacturing, establishing precise reference surfaces before transport. The water guide mechanism centerline and assembly reference lines are pre-established, eliminating the need for time-consuming repositioning and adjustment operations at the construction site.

Inventive Principle:
Principle #10Preliminary action

3Manufacturing precision

If the joint section gap and misalignment are controlled within tolerance, then assembly quality is improved, but it is difficult to meet 100% qualified size in factory preparation

Engineering Contradiction:
Improvegap and misalignment of joint sectionVSAvoiddifficulty of preparing and adjusting joint section
Core Design Contradiction:
Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The patent changes the dimensional parameters and tolerance specifications by eliminating the joint section entirely. Instead of controlling gap and misalignment within tight tolerances, the design accepts larger tolerances for the direct connection interface, simplifying the manufacturing process while maintaining assembly quality through the integrated water guide mechanism.

Inventive Principle:
Principle #35Parameter changes

4Manufacturing precision

If the joint section is prepared twice, then the production cycle is extended, but the manufacturing process becomes more thorough

Engineering Contradiction:
Improvequality of joint section preparationVSAvoidproduction cycle time
Core Design Contradiction:
Manufacturing precisionVSProductivity

Solution Approach 1:

The patent performs all necessary preparation, processing, and quality assurance operations during the initial factory manufacturing phase. The spiral case sections are completely prepared with all machining, welding, and inspection completed before transport, eliminating the need for a second preparation cycle at the construction site.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent skips the second preparation and adjustment cycle entirely by completing all necessary operations during factory manufacturing. The design allows for direct assembly at the construction site without requiring repeated preparation, inspection, and adjustment iterations.

Inventive Principle:
Principle #21Skipping (Rushing through)

5Ease of operation

If the joint section is assembled on construction site with large welding volume, then assembly is completed, but welding stress is high and deformation is significant

Engineering Contradiction:
Improveassembly completeness at construction siteVSAvoidwelding stress and deformation
Core Design Contradiction:
Ease of operationVSStress or pressure

Solution Approach 1:

The patent removes the joint section that required extensive welding operations. The direct connection between the spiral case and stay ring eliminates the need for large-volume welding of transition components, significantly reducing welding stress and deformation at the construction site.

Inventive Principle:
Principle #2Taking out (Extraction)

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 enhances assembly dimensional accuracy, reduces welding stress, and significantly shortens the manufacturing cycle by simplifying the process and improving the quality of the stay ring and spiral case assembly.

Implementation Method 1

welding and annealing them in the factory

Methodology Applied
Scientific EffectAnnealing: Annealing

Implementation Method 2

reduces welding stress, and significantly shortens the manufacturing cycle

Methodology Applied
Scientific EffectStress Relaxation: Stress Relaxation

Data Source

PatentEP4706876A1Manufacturing method for seat ring volute of pumped storage unit
Publication Date: 2026.03.11 DONGFANG ELECTRIC MACHINERY
  • EP4706876A1 patent drawingFigure 1~2
  • EP4706876A1 patent drawingFigure 3~4
  • EP4706876A1 patent drawingFigure 5~6

AI summary

The present disclosure relates to hydraulic turbine manufacturing technology and discloses a method for manufacturing a stay ring and spiral case assembly of a pumped storage unit. In this method, two (left and right) spiral case segments are arranged along a split surface of the stay ring and spiral case assembly, eliminating a "transition plate + joint section" structure at the split surface. The two split segments of the spiral case are cut and formed in one piece, welded and annealed in the factory, and then cut along the split surfaces. The split surfaces of the split segments of the spiral case are processed together with the assembly surfaces of the stay ring, forming the two split segments of the stay ring and spiral case assembly. The two split segments of the stay ring and spiral case assembly are transported to the construction site, where they are rounded and assembled by welding. The entire the stay ring and spiral case assembly only has a circumferential weld on the assembly surfaces. Therefore, the manufacturing method of the present disclosure can improve the assembly dimensional accuracy and welding quality of the split segments of the stay ring and spiral case assembly, and shorten the manufacturing cycle.