X-ray Tube Cathode Filament with Variable Thickness
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Solution Overview
Problem
Existing X-ray tube cathode filaments face issues with mechanical embrittlement at solder zones and uncontrollable deformation during expansion, leading to potential breakage and misalignment with the anode, which affects X-ray production precision.
Innovation Solution
A single-piece cathode filament with varying leg and body thicknesses is manufactured using plasma spraying, allowing for flexible legs to absorb body expansion without altering the anode-cathode distance, achieved by differing plasma spraying times for the body and legs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the cathode filament is made as a single-piece structure to eliminate soldering, then mechanical embrittlement at solder zones is avoided, but the filament body undergoes uncontrollable deformation during thermal expansion
Solution Approach 1:
The patent applies different thicknesses to different parts of the filament structure. The legs are made with a first thickness while the body is made with a second thickness, allowing each part to have different mechanical properties suited to its function. This local differentiation enables the legs to be more flexible while maintaining body strength, resolving the contradiction between overall mechanical strength and localized deformation control.
2Strength
If the legs are made with the same thickness as the body in a single-piece filament, then the structure is mechanically robust, but the rigidity prevents the body from expanding freely causing deformation
Solution Approach 1:
The patent creates local quality differences by specifying that the legs have a first thickness and the body has a second thickness. This allows the legs to have different mechanical properties (more flexible) compared to the body (stronger), enabling the body to expand thermally without being constrained by equally rigid legs, thus improving thermal expansion adaptability while maintaining overall mechanical strength.
3Ease of manufacture
If soldering is used to attach legs to the filament body, then the filament can be assembled from separate parts, but the soldering process causes mechanical embrittlement at the attachment zones
Solution Approach 1:
The patent merges the legs and body into a single-piece filament structure without soldering or other attachment processes. This eliminates the solder zones that cause mechanical embrittlement, improving reliability. The single-piece construction is achieved through plasma spraying, combining what were previously separate components into one integrated structure.
4Stress or pressure
If the filament body is allowed to expand freely during heating, then thermal stress is reduced, but the positioning of the cathode relative to the anode is modified
Solution Approach 1:
The patent uses differential thickness design where the legs have a first thickness and the body has a second thickness. This local quality differentiation allows the body to expand thermally with reduced constraint, lowering thermal stress. Simultaneously, the specifically designed leg structure maintains the cathode-anode positioning precision by providing appropriate support and flexibility.
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 method ensures robust mechanical resistance and precise positioning of the cathode relative to the anode, preventing breakage and deformation, thus maintaining efficient X-ray production.
Implementation Method 1
spraying at least one material on a support by, for example, plasma spraying
Data Source
AI summary
A method for the manufacture of a cathode filament of an X-ray tube and an X-ray tube formed by the method wherein the filament has at least two legs and one body, the filament being a single-piece filament. Spraying at least one material on a support by plasma spraying or by another deposition technique to obtain the filament molded on the support and separating the filament obtained from the support. The filament obtained has a variable thickness and a variable composition. The thicknesses of the legs and of the body as well as the composition of the filament can be modified according to the user's needs.