Modular Thermal Spraying Nozzle Insert Design
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Solution Overview
Problem
Current nozzle structures for thermal spraying, especially those with small inner diameters, face issues with maintaining a stable jet shape, dimensional accuracy, and high production costs, leading to reduced coating quality and increased manufacturing expenses.
Innovation Solution
A modular nozzle assembly comprising a holder and a replaceable nozzle insert with a tubular element and flange-shaped widening, allowing for easy exchange and precise dimensional control, featuring a metal-polymer composite design for improved sealing and thermal insulation, enabling efficient and cost-effective suspension feeding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If nozzle bores are produced by drilling or eroding, then manufacturing flexibility is improved, but manufacturing precision deteriorates due to angular deviations and dimensional inaccuracy
Solution Approach 1:
The nozzle is divided into a holder and a separate nozzle insert. The nozzle insert is manufactured with high precision using injection molding, while the holder provides the mounting structure. This segmentation allows the precision-critical nozzle insert to be produced separately with controlled tolerances, decoupling the precision requirement from the manufacturing process of the entire nozzle assembly.
Solution Approach 2:
The nozzle insert is designed as a replaceable, cost-effective component that can be easily exchanged. Instead of requiring high-precision machining of the entire nozzle, a simpler, less expensive insert can be manufactured with sufficient precision for its function, and replaced when worn or degraded.
2Manufacturing precision
If small inner diameters below 500 μm are used, then coating quality is improved, but jet stability deteriorates due to droplet detachment and jet break-up
Solution Approach 1:
The invention changes the geometric parameters of the nozzle insert, specifically using a length-to-diameter ratio (L/D) between 0.5 and 2.0, with optimal values around 1.0. The inner diameter is maintained between 20-500 μm. These parameter optimizations ensure stable jet formation and prevent droplet detachment while achieving the required coating quality.
Solution Approach 2:
The nozzle insert is designed with specific geometric features that pre-condition the suspension flow before it exits. The tapered bore and optimized L/D ratio prepare the flow in advance to maintain coherence and prevent break-up, ensuring stable jet formation upon exit.
3Ease of manufacture
If conventional nozzle manufacturing methods are used, then production costs are reduced, but manufacturing precision deteriorates
Solution Approach 1:
The invention replaces conventional mechanical drilling or eroding processes with injection molding for manufacturing the nozzle insert. Injection molding provides superior dimensional accuracy and surface finish while being more cost-effective for production. The polymer material of the insert also eliminates the need for expensive precision machining operations.
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 solution provides a reliable, reproducible, and cost-effective means to maintain consistent suspension feeding, enhancing coating quality and reducing manufacturing costs by allowing for quick replacement of nozzle inserts and precise dimensional control.
Implementation Method 1
the surfaces of the flanged enlargement and the seat are in direct contact with one another, so that an end stop and a seal are formed in this area
Implementation Method 2
The nozzle insert has a tubular element arranged in the direction of the burner chamber or perpendicularly to the HVOF flame/plasma torch
Implementation Method 3
In the combustion chamber, the particles can be heated and accelerated with a gaseous or liquid fuel using the so-called High Velocity Oxy Fuel Process (HVOF) by oxidizing the fuel
Implementation Method 4
In the combustion chamber, the particles can be heated and accelerated with a gaseous or liquid fuel using the so-called High Velocity Oxy Fuel Process (HVOF) by oxidizing the fuel
Implementation Method 5
With the atmospheric plasma spraying process (APS), the suspension is fed into the plasma torch. There, the suspension liquid is evaporated and the resulting particles are heated.
Implementation Method 6
A new or different nozzle insert can have a different inner diameter of the tubular element and/or a different length of the tubular element
Data Source
Figure 1
AI summary
The invention relates to the nozzle construction for thermal spraying by means of a suspension, in which particles are contained, or a precursor solution, by means of which particles or precursor solution a layer is formed on a substrate, and which suspension or precursor solution is fed into a burner chamber or into a plasma torch, in which heating and acceleration of the particles is achieved, wherein a connection point for feeding the suspension or the precursor solution, a holder, and a nozzle insert are present. The nozzle insert has, with a tubular element arranged in the direction of the burner chamber or perpendicularly in HVOF flame or plasma torch and with an end face arranged opposite the burner chamber, a flange-shaped expanded section, which lies against a seat formed in the holder in the installed state. The contours of the flange-shaped expanded section and of the seat are complementary to each other such that the surfaces of the flange-shaped expanded section and of the seat are in direct contact with each other and an end stop and a seal are formed in this region.