Turbine Blade Tip Recess via Dual-Core Ceramic Mold
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Solution Overview
Problem
Existing turbine blade manufacturing methods face challenges in maintaining structural integrity and effective cooling at high temperatures, particularly with tip wall holes where braze material melts and causes cooling air leakage, and machined tip recesses that can become misshapen due to core shifting during the manufacturing process, leading to increased costs and inefficiencies.
Innovation Solution
A method involving a ceramic mold with two adjacent cores, where one core complements the tip wall and the other has protrusions or depressions to secure its position, allowing for precise formation of a tip recess without the need for braze materials, ensuring effective cooling and structural integrity at high temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If tip wall holes are sealed with braze material, then cooling air leakage is prevented at lower temperatures, but the braze material melts at high temperatures causing cooling air leakage
Solution Approach 1:
The invention removes the braze material sealing method entirely and replaces it with a mechanical seal formed by the tip recess structure itself. The tip recess creates a labyrinthine path that prevents cooling air leakage without requiring temperature-sensitive sealing materials.
Solution Approach 2:
Instead of trying to seal the holes directly, the invention inverts the approach by creating a recessed tip wall structure that allows the cooling air to follow a controlled path around the tip, effectively sealing through geometry rather than material sealing.
2Manufacturing precision
If precision locating strategies are used to prevent core shifting, then tip recess accuracy is improved, but manufacturing costs increase significantly
Solution Approach 1:
The cores are pre-positioned with built-in locating features (protrusions and recesses) before the casting process. This preliminary positioning ensures accurate tip recess formation without requiring expensive post-casting verification or adjustment techniques.
Solution Approach 2:
The core design includes self-locating features where protrusions on one core fit into recesses on another core, creating automatic positioning during assembly. This self-service mechanism eliminates the need for external precision locating strategies and expensive verification processes.
3Device complexity
If a single integrated core is used to form both internal cooling circuit and tip recess, then manufacturing process is simplified, but core shifting occurs causing tip wall misshapen
Solution Approach 1:
The invention divides the core assembly into multiple separate cores, each responsible for forming specific features. The first core forms the internal cooling circuit while the second core forms the tip recess, eliminating interference and shifting problems between features.
Solution Approach 2:
Multiple separate cores are nested together within the ceramic mold cavity, with each core positioned and secured by locating features. This nested arrangement allows complex blade geometries to be formed while maintaining precision through the modular core structure.
Data Source
AI summary
A core assembly including two cores is used to manufacture a blade. The first core has an outer surface shaped to complement the tip wall bottom surface. The second core has a tip surface, a side surface, and a protrusion or a depression. The tip surface is shaped to complement at least a portion of the tip wall top surface and is configured to be disposed proximate the first core. The side surface is shaped to complement at least a portion of the side wall, and the protrusion extends from the second core side surface to contact at least a portion of the ceramic mold inner surface. In embodiments employing a depression, the depression is formed in the side surface.