Frustoconical Protective Bell for Hardfacing Oxidation Control
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Solution Overview
Problem
Existing methods for protecting metal parts during hardfacing processes, such as those used in aeronautics, fail to prevent oxidation due to turbulence in the gas flow at the junction between the protective bell and the metal part, allowing oxygen to penetrate and cause oxidation despite the use of inert gases.
Innovation Solution
A protective bell with a frustoconical inner surface between the gas inlet orifice and the lower end, which reduces gaseous disturbances and creates a more hermetic enclosure by aligning the inner surface with the outer surface of the spray nozzle, minimizing air inlets and enhancing the protection against oxidation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a protective bell with inert gas injection is used, then oxidation protection is improved, but gas flow turbulence at the junction between the bell and metal part causes oxygen ingress
Solution Approach 1:
The invention changes the geometric parameter of the protective bell's inner surface from cylindrical to frustoconical. This parameter change modifies the gas flow pattern, allowing the inert gas jet to attach to the inclined surface and follow it downward, preventing turbulence and oxygen ingress at the junction between the bell and metal part.
Solution Approach 2:
The invention utilizes gas flow attachment to the frustoconical surface, where the inert gas injected through the lateral orifice attaches to the inclined inner surface and flows downward along it. This pneumatic principle prevents the formation of turbulent eddies and maintains a stable inert atmosphere at the critical junction area.
2Device complexity
If a cylindrical protective bell is used, then the structure is simple, but gas flow turbulence occurs at the junction allowing oxygen penetration
Solution Approach 1:
The invention modifies the geometric parameter of the protective bell by introducing a frustoconical inner surface section. This change, while adding some manufacturing complexity, creates a surface that guides gas flow smoothly and prevents turbulence, thereby achieving a more reliable hermetic enclosure that effectively blocks oxygen penetration.
3Quantity of substance
If inert gas is injected laterally into the protective bell, then the enclosure is filled with inert gas, but turbulence at the lower end allows oxygen to be sucked in
Solution Approach 1:
The invention changes the geometry of the inner surface to frustoconical, which redirects the laterally injected inert gas flow to attach to and flow down along the inclined surface. This parameter change ensures that the inert gas fills the enclosure effectively while preventing turbulence and oxygen suction at the lower end junction.
Solution Approach 2:
The invention applies the principle of gas flow attachment to the frustoconical surface. The inert gas injected laterally attaches to the inclined surface and flows downward in a controlled manner, ensuring proper enclosure filling while maintaining laminar flow that prevents oxygen ingress at the critical lower junction area.
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
The frustoconical design of the protective bell significantly reduces turbulence and oxygen ingress, creating a more effective hermetic enclosure that better protects metal parts from oxidation during the hardfacing process, ensuring a more reliable and efficient protection against oxidation.
Implementation Method 1
the oxidation of the metal parts during the reloading processes of the prior art, despite the presence of protective bells, was due to turbulence in the gas flow which takes place at the junction between the protective bell and the metal part to be recharged
Implementation Method 2
the parts to be rebuilt are generally made of titanium, nickel, aluminum or even cobalt, and therefore they present a risk of oxidation during the hardfacing process
Data Source
AI summary
The invention concerns a protection cover (20) suitable for being placed between a spray nozzle (1) and a metal part during a process of resurfacing the metal part, the protection cover (20) comprising a side wall (21) extending along a reference axis (22), the side wall (21) comprising an inner surface (30) and an outer surface (27), the side wall (21) having a lower end (25) and an upper end (23), the side wall (21) being perforated by at least one lateral gas inlet port (31), the lower end (25) of the side wall (21) being perforated by a notch (26) into which a portion of the metal part can be inserted, the upper end (23) of the side wall (21) being provided with an opening (24) into which a portion of the spray nozzle (1) can be inserted; characterised in that the inner surface (30) of the side wall (21) comprises at least one frustoconical portion.