Impeller Welding Core for Hub Deformation Control
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Solution Overview
Problem
The challenge in manufacturing impellers lies in minimizing deformation of the hub and cover due to welding, particularly in narrow tip-openings where conventional welding methods result in significant deformation, making it difficult to meet the stringent dimensional accuracy requirements of modern rotating machines.
Innovation Solution
A method involving the use of a core interposed between the hub and cover, with through-holes conforming to the blade shapes, to physically restrain deformation during cooling, and subsequent removal of the core after welding to maintain space without deformation, along with inert gas protection to prevent oxidation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If welding is performed in a narrow tip-opening without a core, then the welding process can be completed, but large deformation occurs in the hub due to contractive force during cooling
Solution Approach 1:
A core made of heat-resistant material is introduced as an intermediary component between the hub and cover during welding. The core includes through-holes that receive the welding rod and provide a pathway for welding material to reach the narrow tip-opening. This intermediary structure enables the welding process while simultaneously restraining deformation of the hub during cooling, as the core maintains the spatial relationship between components.
Solution Approach 2:
The patent changes the physical state and properties of the welding environment by introducing a core that modifies the thermal field distribution during welding. The core absorbs and distributes heat, changing the temperature parameters and cooling rate of the hub, thereby reducing thermal stress and deformation. The core's presence transforms the welding process from a direct joint operation to a controlled thermal process with restrained deformation.
2Productivity
If the tip-opening between hub and cover is narrowed to reduce size, then machine performance improves, but conventional welding becomes difficult as welding rod cannot be inserted to the back of blade
Solution Approach 1:
The patent solves the accessibility problem by transitioning from a two-dimensional welding approach (inserting rod from the back) to a three-dimensional approach using the core's through-holes. The core provides vertical pathways through which welding material can be delivered to the narrow tip-opening, effectively adding a new dimension for material delivery and enabling welding in previously inaccessible narrow spaces.
3Ease of manufacture
If hub and cover are fixed by fixture on outer circumference side only, then welding can be performed, but large deformation occurs at the inner circumference side and boss portion
Solution Approach 1:
The core acts as a mediating support structure that distributes and restrains deformation forces during welding. While the fixture provides external support at the outer circumference, the core provides internal support throughout the welding zone, particularly protecting the boss portion and inner circumference side from excessive deformation by maintaining structural integrity during the welding process.
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 significantly reduces deformation, improves production efficiency, and lowers manufacturing costs by ensuring precise dimensional accuracy and preventing oxidation during the welding process.
Implementation Method 1
the contractive force at the time of natural cooling after the welding
Implementation Method 2
filling an inert gas from the vent hole into a space among the hub, the cover and the core, before the step of welding the hub and the blades
Data Source
Figure 1(A)~1(D)
Figure 2
Figure 3
AI summary
A method of manufacturing an impeller, the method including: a step of forming a cover that is provided with a plurality of blades; a step of disposing a core on the cover such that the core is interposed between the blades; a step of disposing a hub on the blades, the hub being a plate on which grooves conforming to shapes of the blades are formed; and a step of welding the hub and the blades, wherein through-holes conforming to the shapes of the blades are provided on the core, such that the blades are fitted in the core when the core is disposed.