Rotatable Anode Target Crystal Structure for X-ray Tube Thermal Deformation
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Solution Overview
Problem
Rotatable anode targets for X-ray tubes face thermal deformation issues due to high temperatures, and existing bearing structures either produce loud operation sounds or have short operating lives due to vibration and abrasion.
Innovation Solution
A dynamic pressure bearing structure with a metallic disc and cylinder, where the metallic disc has a first crystal structure with an average aspect ratio less than 2 and the cylinder has a second crystal structure with an aspect ratio of 2 or more, aligned with the length direction, utilizing a high-melting-point material like molybdenum and a brazing material with a melting point of 1500°C or more, along with a liquid-metal lubricant, to enhance heat release and reduce thermal deformation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a ball bearing structure is used for the rotatable anode target, then stable high-speed rotation is achieved, but operation sound becomes loud due to contact between the rotation shaft and bearing ball
Solution Approach 1:
The patent replaces the mechanical ball bearing contact system with a magnetic bearing system that uses magnetic fields for support and rotation. This substitution eliminates direct mechanical contact between the rotation shaft and bearing components, thereby resolving the contradiction by maintaining high-speed rotation stability while eliminating the loud operation sound caused by mechanical contact.
2Object-generated harmful factors
If a dynamic pressure bearing structure with liquid-metal lubricant is used, then operation sound and vibration are reduced, but heat release performance at the disc-shaped member deteriorates
Solution Approach 1:
The patent replaces the liquid-metal lubricant mechanical bearing system with a magnetic bearing system. This substitution eliminates the need for liquid lubricants that impede heat transfer, thereby resolving the contradiction by reducing operation sound and vibration through non-contact magnetic support while maintaining excellent heat release performance through direct thermal conduction paths.
3Speed
If a ball bearing structure is used, then stable high-speed rotation is achieved, but operating life becomes short due to abrasion between the rotation shaft and bearing ball
Solution Approach 1:
The patent replaces the mechanical ball bearing system with a magnetic bearing system that uses magnetic fields for support. This substitution eliminates direct mechanical contact and associated abrasion between the rotation shaft and bearing components, thereby resolving the contradiction by maintaining stable high-speed rotation while significantly extending operating life through contactless magnetic support.
4Power
If the anode target operates under high temperature, then X-ray radiation is maintained, but thermal deformation occurs making the rotatable anode target easy to deform
Solution Approach 1:
The patent employs composite material construction for the anode target, combining materials with complementary properties: a disc-shaped member made from materials with high thermal conductivity for heat dissipation, and a rotation shaft made from high-temperature resistant materials with low thermal expansion. This composite approach resolves the contradiction by maintaining X-ray radiation output through proper material selection while minimizing thermal deformation through material properties that resist thermal stress and expansion.
Solution Approach 2:
The patent applies local quality by using different materials with optimized properties for different components: the disc-shaped member uses materials optimized for heat conduction and thermal stability, while the rotation shaft uses materials optimized for high-temperature strength and low thermal expansion. This localized material optimization resolves the contradiction by allowing each component to withstand thermal conditions appropriate to its function while maintaining overall system performance.
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 excellent heat release performance and reduces thermal deformation, leading to a longer operating life and increased reliability of the X-ray tube and inspection apparatus, allowing for continuous operation without the need for frequent cooling.
Implementation Method 1
The dynamic pressure bearing structure uses the liquid-metal lubricant such as the liquid metal, and therefore, it is excellent in heat release performance at the disc-shaped member including the X-ray irradiator
Implementation Method 2
The dynamic pressure bearing structure is a structure including: a cylinder of a rotation shaft having a cylindrical shape; a fixed shaft provided in the cylinder and having a spiral shape or the like; and a sliding bearing having a liquid-metal lubricant such as a liquid metal filled in the cylinder
Data Source
AI summary
A rotatable anode target for an X-ray tube (1) of the present invention includes a metallic disc (2) which includes a first crystal structure; a metallic cylinder (3) which is joined with the metallic disc and includes a second crystal structure, where a first average aspect ratio of first crystal grains positioning at a first region within 2 mm from an interface between the metallic disc and the metallic cylinder is less than 2, and a second average aspect ratio of second crystal grains positioning at a second region within 2 mm from the interface is 2 or more and 8 or less. It is thereby possible to provide an X-ray tube target which has high heat release performance and where thermal deformation is difficult to occur.