Rotor Vertical Welding Sequence to Prevent Oxidation
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Solution Overview
Problem
The existing method of welding rotors by stacking elements vertically poses a risk of oxidation at the lower part of the pile due to the presence of oxygen, as inert gases used for purging are lighter than oxygen and cannot effectively discharge it from the lower sections during the welding process.
Innovation Solution
The method involves sequentially welding the slots from the top to the bottom, ensuring that oxygen is discharged before reaching the lower part, using a specific sequence and purging technique with inert gases like H2 and N2, and applying under-pressure to minimize oxygen presence, and then tilting the pile for final welding and machining.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If elements are stacked vertically for welding, then welding accessibility and process simplicity are improved, but oxygen accumulation at the lower part causes oxidation risk during welding
Solution Approach 1:
The patent inverts the conventional welding sequence by welding slots from the top of the vertical stack downward instead of from bottom to top. This inversion ensures that oxygen, being heavier than inert gas, accumulates at the lower sections and does not interfere with welding operations at upper levels, thereby eliminating oxidation risk while maintaining vertical stacking benefits
Solution Approach 2:
The patent changes the welding sequence parameter (from bottom-up to top-down) and utilizes the density parameter difference between oxygen and inert gas to control oxygen distribution, ensuring oxygen-free welding environments at each slot position throughout the vertical stack
2Object-affected harmful factors
If inert gas purging is used during welding, then oxidation protection is improved, but oxygen discharge from lower sections is insufficient due to gas density differences
Solution Approach 1:
The patent inverts the purging strategy by welding from top to bottom, allowing oxygen to naturally settle at the lowest sections due to its higher density. This ensures that inert gas effectively displaces oxygen from welding zones throughout the vertical stack, as oxygen cannot rise against the inert gas flow when welding proceeds downward
Solution Approach 2:
The patent replaces active mechanical oxygen removal systems with passive gravitational separation, utilizing the density difference between oxygen and inert gas to achieve automatic oxygen discharge from lower sections without requiring complex pumping or forcing mechanisms
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 the risk of oxidation during the welding process, ensuring high-quality welds by maintaining a low oxygen environment within the pile, thereby preventing oxidation issues and ensuring robust rotor manufacturing.
Implementation Method 1
the mutually connected cavities are purged with an inert gas or mixture of gases
Implementation Method 2
a welding is realised within the slots completely filling them in, while at the same time melting the collars
Implementation Method 3
thermal treatments are carried out
Data Source
Figure 1
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AI summary
A method for manufacturing a rotor by welding a plurality of elements (1) together is described. The elements (1) have a body (2) with cavities (3) and surfaces (4, 5) to be welded to surfaces (6, 7) of adjacent elements (1). According to the method, the elements (1) are vertically stacked one above the other to form a pile (10) with facing surfaces (4, 5, 6, 7) to be welded together defining slots (11). The cavities (3) of adjacent elements (1) define bores (12) that extend within the pile (10). Then adjacent elements (1) are welded together within the slots (11). The bore (12) is purged with an inert gas or mixture during welding. The slots (11) are welded at an upper part of the bore (12) before the slots (11) at a lower part of the bore (12), and a slot (11) at the upper part of the bore (12) is welded last.