Ring Seal Midplate Hardface Coating Eccentricity Control
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Solution Overview
Problem
Current ring seal designs in rotary machines face challenges with hardface coating processes due to geometric constraints, leading to quality defects and increased costs, as the radial location of extension features on spacers or seal plates is close to the inner diameter of the hardface region, causing issues during manufacturing and inspection.
Innovation Solution
The introduction of a ring seal midplate that sets an allowable eccentricity of the ring seal with respect to the shaft centerline during installation, allowing for optimized geometry and separate hardface coating of components before assembly, which alleviates the geometric constraints and improves wear resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the extension feature OD is used to prevent ring seal eccentricity, then the ring seal positioning is improved, but the hardface coating quality deteriorates due to geometric constraints
Solution Approach 1:
The invention divides the sealing structure into separate components: the extension feature is integrated with the seal plate while the spacer becomes a distinct element. This segmentation allows the seal plate to provide precise positioning through its extension feature, while the spacer can be separately manufactured and coated without geometric constraints, thereby resolving the conflict between positioning precision and coating quality
Solution Approach 2:
The invention introduces a midplate as an intermediary component between the seal plate and spacer. This midplate serves as a mediator that maintains the functional relationship between components while allowing each to be optimized independently - the seal plate extension feature provides positioning, the midplate provides spacing and alignment, and the spacer can be freely coated
2Reliability
If the extension feature OD is located radially underneath the ring seal, then the ring seal eccentricity is controlled, but the manufacturing complexity increases due to geometry constraints for hardface spray processes
Solution Approach 1:
By segmenting the structure so that the extension feature belongs to the seal plate and the spacer is a separate component, the invention simplifies the manufacturing process. The seal plate can be manufactured with its extension feature for eccentricity control, while the spacer can be separately coated without geometric constraints, reducing overall manufacturing complexity
Solution Approach 2:
The invention allows the spacer to be pre-coated with hardface material before assembly, since it no longer has geometric constraints from the extension feature. This preliminary action eliminates the need for complex in-situ coating operations and reduces manufacturing process complexity while maintaining reliability
3Strength
If hardface coating is applied to the seal plate and spacer, then the wear resistance is improved, but the manufacturing time and cost increase due to inspection, removal and repair of defects
Solution Approach 1:
The invention segments the coating process by allowing the spacer to be coated separately without geometric constraints, eliminating defects that would require repair. This segmentation maintains wear resistance while reducing the time lost to inspection and repair activities
Solution Approach 2:
The spacer can be pre-coated with hardface material before assembly into the final structure, since the geometric constraints are eliminated. This preliminary action allows for better coating quality, reduced defects, and less time spent on post-coating inspection and repair, while still providing the necessary wear resistance
Data Source
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AI summary
A seal assembly for a rotary machine which includes a rotor assembly having a rotatable rotor shaft is disclosed. The seal assembly may comprise a spacer, a seal plate, a ring seal, and a ring seal midplate. The spacer, the seal plate, and the ring seal midplate may be rotatable with the shaft and extend outwardly from the shaft. The ring seal is free and provides a seal for a bearing compartment of the rotary machine. The ring seal midplate is not attached to the spacer or the seal plate during a hardface process which is applied to any component of the seal assembly. The ring seal midplate may be longitudinally located between the spacer and the seal plate and be radially spaced between the ring seal and the shaft.