CN102194632A - Interface for liquid metal bearing and manufacture method thereof - Google Patents
Interface for liquid metal bearing and manufacture method thereof Download PDFInfo
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- CN102194632A CN102194632A CN2011100427624A CN201110042762A CN102194632A CN 102194632 A CN102194632 A CN 102194632A CN 2011100427624 A CN2011100427624 A CN 2011100427624A CN 201110042762 A CN201110042762 A CN 201110042762A CN 102194632 A CN102194632 A CN 102194632A
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Abstract
The invention relates to an interface for a liquid metal bearing and a manufacture method thereof. Specifically, an x-ray tube (4) comprises a cathode (36) and a target assembly located to receive electron emitted by the cathode. The target assembly comprises a target (32) and a spiral groove bearing (SGB) (34) configured to support the target (32). The SBG (34) comprises a fixed component (41) having a first surface and attached on first materials (72, 74, 76) on the first surface and having a second surface and attached on second materials (70, 78, 80) on the second surface, wherein the fixed component (41) is located to form clearances between the first materials (72, 74, 76) and the second materials (70, 78, 80); and liquid metals (50) located in the clearances, wherein at least one of the first and second materials (70, 72, 74, 76, 78, 80) contains tantalum.
Description
The cross reference of related application
The application is that the U.S. Patent Application Serial Number of submitting on March 25th, 2009 is 12/410,518 part continuity application and requires its priority.
Technical field
Embodiments of the invention relate generally to x ray tube, and relate more particularly to wherein combine the X-ray tube of spiral groove bearing (SGB).
Background technology
X-ray system typically comprises x ray tube, detector and is used for the supporting construction of this x ray tube and detector.In operation, object is positioned thereon one-tenth entablement between x ray tube and detector.The x ray tube is typically towards the radiation of object emission such as x ray.This radiation is typically passed into the object on the entablement and is impinged upon on the detector.When object was passed in radiation, the internal structure of object caused the spatial variations in the radiation of detector place reception.Detector sends the data that received then, and system converts radiation variation to image, and this image can be used to assess the internal structure of object.One skilled in the art will recognize that this object can include but not limited to during the imaging of medical the patient and such as the lifeless object in x ray scanning machine or computed tomography (CT) the package scans machine for example.
The x ray tube comprises negative electrode and the anode that is positioned at high vacuum environment.Anode construction typically supports and is rotated so that be distributed in the heat that the focus place produces by ball bearing.Typically, adopt induction motor to come rotarting anode, this induction motor has the cylindrical rotor that is placed in the cantilevered axle that supports the dish type plate target, and the definitely minor structure that has the copper winding of the elongated neck of surrounding the x ray tube.The rotor of rotating anode assembly is driven by stator.X ray tube negative electrode provides crosses over anode quickened and produced the x ray after clashing into anode to the cathode vacuum gap focused beam.Because the high temperature that is produced when the electron beam impact target need be with high rotating speed rotating anode assembly.This has proposed strict demand to ball bearing.
Can adopt the liquid metal bearing to replace ball bearing.The advantage of liquid metal bearing comprises high load capability and the high thermal heat transfer capability that obtains owing to the amount of comparing the contact area of increase with ball bearing.Advantage also comprises low noise operation well known in the art.Typically use gallium and alloy thereof as liquid metal, because they tend at room temperature be in a liquid state and have enough low steam pressure to satisfy the strict high vacuum requirement of x ray tube under operating temperature.
Gallium tends to be high response and corrosivity.Therefore, the parent metal that tolerates this type of corrosion is desired.Therefore, typically use such as the refractory metal of molybdenum as the base material that is used for SGB, and as known in the art typically in the surface processing spiral groove so that pump-absorb action is provided liquid metal is maintained its ideal position.This type of material is not only corrosion-resistant, and it tends to vacuum compatible and therefore make itself be suitable for the x ray tube applications.Yet a problem that may run between the operating period of liquid metal is to guarantee enough wettabilities of bearing surface and liquid metal.When not producing enough wettabilities, liquid metal is not exclusively filled SGB and SGB and during use may not can be connected the gap and distribute liquid metal equably, thereby has shortened the life-span of x ray tube.
Wettability may since parent metal before assembling and/or assembly process is exposed to air or moisture is subjected to negative effect, thereby cause on it formation oxide layer.Oxide layer makes the wettability of piece surface and liquid metal worsen again.Adopt known technology to improve or kept the wettability of base material under these situations.A kind of technique known is included in the hydrogen at about 800 ℃ of burning bearing surfaces down, then part is stored in oxygen barrier atmosphere such as in nitrogen or the argon gas till using.Another kind of technique known comprises utilizes for example physical vapor deposition (PVD) technology carbide, boride or nitride coated bearing part.
Another kind of technique known comprises utilizes PVD coating molybdenum as the diffusion obstacle.Yet though can adopt molybdenum when utilizing PVD to apply this type of diffusion obstacle, the base material of diffusion obstacle is typically identical with base material.Alternatively, utilize the material be different from base material to tend to be limited in the thickness of 2000nm for suitable application so that avoid because the coated obstacle and the thermal mismatching of parent metal ftracture by the material of PVD coating.Can have with the coating of the similar coefficient of expansion of parent metal by employing and alleviate thermal mismatching to a certain extent.Yet this type of solution tends to limit the quantity of parent metal/coating option.In addition, because thickness limits, got rid of this type of material, thereby made and must apply diffusion obstacle with the interior thickness of the desirable finally tolerance that falls into final part from the later stage machine work.Equally, because thickness limits, this type of still makes base material must tolerate the corrosiveness of liquid metal such as molybdenum in order to improve infiltrating solution.Yet, molybdenum as base material and processing and processing aspect all very expensive.
A kind ofly be used to make the base material expense minimum and to improve functional technology be only to comprise preferred parent metal (being molybdenum) in the zone that will contact liquid metal.The ennation of being made by cheap material then can be by brazing or otherwise is attached on it, and this ennation is as the mechanical fastener that is used for the strutting piece of anode.In other words, for example, static central shaft can support the rotatable supporting construction with the anode that is attached on it.This central shaft can be made by preferred parent metal fully, thereby perhaps its cost can reduce by being attached to the total amount that reduces the preferred substrate metal on it than cheap steel via brazing or other attachment method.This type of design can be owing to using cheap steel partly to replace preferred parent metal to save cost.Yet, utilize cost savings that this technology realizes typically owing to extra attached processing, for example departing to a certain degree takes place owing to the ennation that will have seal is attached thereon.
A shortcoming using molybdenum is that molybdenum can be formed on the unsettled intermetallic compounds layer that has gallium under the typical operation temperature of SGB.Therefore, intermetallic compounds layer tends to owing to contacting between solid-state molybdenum surface and the liquid gallium forms, if play the effect of grinding agent thereby this intermetallic compounds layer tends to rupture, or (this too early life-span that can cause SGB lost efficacy) plays the effect of particulate when contacting between stationary components and rotating part.The formation of intermetallic compounds layer is the function of temperature and obeys the aging principle of Arrhenius (Arrhenius) as known in the art.
Therefore, SGB can make and adopt gallium conduct liquid metal wherein by molybdenum, and for correct operation and processing, the SGB that so makes can provide enough performances for the life-span of x ray tube.Yet it is expensive that the molybdenum parent metal tends to, and only with zone that gallium contacts in have a molybdenum coating alternative SGB generally include expensive brazing step.The processing of molybdenum or molybdenum coating also comprises extra cost, and extra infiltration step (that is, in the hydrogen environment, burning) be with based on the relevant expensive treatment step of the SGB of molybdenum.In addition, molybdenum is formed on unsettled intermetallic compound under the typical operation temperature, and along with imaging applications is tended to the power increase, operating temperature raises equally, thereby quickens the growth and the formation of compound layer between molybdenum-gallium metal.
Therefore, wish to have equipment and the method that reduces and make the total cost relevant with use SGB.
Summary of the invention
Equipment and method by providing material to overcome aforesaid drawbacks on the surface of SGB member is provided embodiments of the invention.
According to an aspect of the present invention, the x ray tube comprises negative electrode and the target assembly that is oriented to receive from the electronics of cathode emission.This target assembly comprises target and is configured to support the spiral groove bearing (SGB) of this target.This SGB comprises the rotating parts that has first surface and invest first material on the first surface; Have second surface and the static component that invests second material on the second surface, this static component is positioned such that the gap is formed between first material and second material; And be positioned in liquid metal in this gap, wherein at least one in first material and second material comprises tantalum.
According to another aspect of the present invention, target assembly comprise have the axle that invests first material on its outer surface, be configured to support target and have the sleeve pipe that invests second material on its inner surface and be positioned in first material and second material between liquid metal, wherein at least one in first and second materials comprises tantalum.
According to of the present invention more on the other hand, the method that a kind of manufacturing is used for the target assembly of x ray tube comprises the steps: to provide the axle that has outer surface material and have external diameter; Sleeve pipe is provided, and this sleeve pipe has the aperture of the inner surface material that exposes sleeve pipe, and wherein the diameter of inner surface material is greater than the external diameter of outer surface material; Ground floor is coated on the inner surface material, and the second layer is coated on the outer surface material.This method comprises that also in the acid etching ground floor and the second layer at least one is to remove oxide from it, target is attached on one in axle and the sleeve pipe, axle is inserted sleeve pipe forming the pipe spreader assembly, and liquid metal is coated on one in the ground floor of pipe spreader assembly and the second layer.
Various further features and advantage will become obvious from following the detailed description and the accompanying drawings.
Description of drawings
Accompanying drawing illustrates a preferred embodiment of the current imagination in order to implement the present invention.
In the accompanying drawings:
Fig. 1 is the block diagram that combines the imaging system of embodiments of the invention.
Fig. 2 is according to one embodiment of present invention and the sectional view of the part of the x ray tube that can use with the system shown in Fig. 1.
Fig. 3 is the sectional view of spiral groove bearing according to an embodiment of the invention (SGB).
Fig. 4 is the perspective view of the material members of the SGB of being used for according to an embodiment of the invention.
Fig. 5 is the technology that is used to make SGB according to an embodiment of the invention.
The diagrammatic sketch of the x ray system that Fig. 6 right and wrong invasive parcel detection system is used together.
The parts inventory
The 2x radiation imaging system
4x ray tube or source
The 6x beam
8 objects
10 detectors
12 processors
14 computers
16 operator's consoles
18 display units
20 storage devices
22 source controllers
24 frameworks
28 radiated emission passages
30x ray tube volume
32 targets or anode
34 bearing assemblies
34 bearing components
36 negative electrodes
38 rotors
40 center lines
41 central shafts
42 sleeve pipes
44 first ends
46 second ends
50 liquid metals
54 radial projection
55 axial surfaces
56 radial cavities
58 removable cover caps
60 for example, the potential difference between them
62 supply pipelines
64 cooling agents
66 inlets
68 outlets
69 removable end caps
70 comprise corresponding material or coating
72 comprise corresponding material or coating
73 internal diameters
74 in this embodiment, preformed member
76 in this embodiment, preformed member
78 in this embodiment, preformed member
80 in this embodiment, preformed member
81 external diameters
82 optional attached or bond materials
83 are configured to be attached on the external diameter
85 internal diameters
87 quilts are comprised being used for attachment component
89 comprise the material capped end
90 for example,
92 start from square frame
94 and SGB assemble at square frame
96 in square frame coating tantalum coating
98 carry out post-processed at square frame to part
100 at square frame
102 assemble at square frame
104 at square frame
106 finish at square frame
410 are not
The 500x ray system
502 saddles
504 openings
The 506x ray tube
508 detector assemblies
510 transfer systems
512 conveyer belts
514 by support structure
516 pass through parcel or baggage item automatically and continuously
518 are not
Embodiment
Fig. 1 is designed to not only to obtain raw image data but also handles this view data so that show and/or the block diagram of an embodiment of the x radiation imaging system 2 analyzed according to the present invention.Those of skill in the art it should be understood that the present invention can be applicable to the medical imaging system of numerous use x ray tubes, for example x ray or breast x line photographic system.Other imaging system also is benefited from the present invention as obtaining a certain amount of image three-dimensional data computing machine tomography (CT) system and digital radiography (RAD) system.Below the discussion of imaging system 2 is the example of such embodiment and is not to be intended to form is limited.
As shown in fig. 1, imaging system 2 comprises x ray tube or the source 4 that is configured to pass object 8 projection x beams 6.Object 8 can comprise the object that human body, baggage item or other hope scan.X radiographic source 4 can be to produce to have scope and typically is from the conventional x ray tube of the x ray of the frequency spectrum of the energy of 30keV to 200keV.X ray 6 passes object 8 and impinges upon on the detector 10 after by object 8 decay.Each detector in the detector 10 all produces the analog electrical signal of the intensity of the x beam of representing bump, and therefore produces attenuated beam when the x beam passes object 8.In one embodiment, detector 10 is the detector based on flash of light, yet also imagination also can adopt direct conversion hysteria detector (for example, CZT detector etc.).
Fig. 2 illustrates the sectional view of the x radiographic source 4 that combines embodiments of the invention.X radiographic source 4 comprises framework 24, has the radiated emission passage 28 that allows x ray 6 to pass wherein in the framework 24.Framework 24 sealing x ray tube volumes 30, this volume holds target or anode 32, bearing assembly 34 and negative electrode 36.Bearing assembly 34 will be described in Fig. 3 in more detail.
Between high-velocity electrons are by means of negative electrode 36 and anode 32, for example under the situation that CT uses be 60 kilovolts or above potential difference generation x ray 6 when when negative electrode 36 is drawn towards anode 32, slowing down suddenly.X ray 6 is launched towards detector array (for example detector 10 of Fig. 1) by radiated emission passage 28.For fear of anode 32 because these electronics and overheated, rotor 38 make anode 32 for example under 90-250Hz around center line 40 with high speed rotating.Anode 32 is attached on the sleeve pipe 42 at first end, 44 places, and rotor 38 is attached on the sleeve pipe 42 at second end, 46 places.Except that the rotation of anode 32 in x ray tube 4, in CT uses, make x ray tube 4 as a whole typically to be 1Hz or faster speed around object (as the object 8 of the imaging system among Fig. 1 2) rotation.Bearing assembly 34 comprises having the enough load bearing abilities that are used in imaging system 2 operation and the spiral groove bearing (SGB) of acceptable noise level.
Referring now to Fig. 3, show the sectional view of SGB according to an embodiment of the invention.Bearing assembly 34 comprises the central shaft 41 that is positioned in the sleeve pipe 42.Sleeve pipe 42 is configured to the supporting anodes (not shown), for example the anode 32 of Fig. 2.Bearing assembly 34 comprises the liquid metal 50 that is positioned between central shaft 41 and the sleeve pipe 42.In an embodiment of the present invention, liquid metal 50 can comprise for example gallium and gallium alloy.Persons skilled in the art will recognize that the invention described in the literary composition can be applicable to any liquid metal bearing.As known in the art, central shaft 41 and sleeve pipe 42 typically comprise and force liquid metal 50 to remain on spiral groove (not shown) between central shaft 41 and the sleeve pipe 42 during sleeve pipe 42 rotation.As a result, liquid metal 50 is keeping being evenly distributed on during sleeve pipe 42 rotation around the central shaft 41, thereby improves its lubricant effect and increase the load capacity of bearing assembly 34.
As shown in Figure 3, bearing assembly 34 comprises central shaft 41, and central shaft 41 is static in the present embodiment, and bearing assembly 34 comprises and is configured to revoling tube 42 that target is attached thereon.Liquid metal 50 is positioned between member 41 and 42.One skilled in the art will recognize that according to embodiments of the invention, can comprise other bearing construction.For example, one skilled in the art will recognize that bearing assembly 34 interchangeable works comprise static external member and have the rotary middle spindle that is attached at the target on it.As another example, one skilled in the art will recognize that bearing assembly 34 can be to be configured to target is supported on " straddling " bearing between the first and second liquid metal bearings.In other words, embodiments of the invention can be bonded to any bearing construction that utilizes the liquid metal bearing to come supporting anodes or target.This class formation can comprise quiescent center axle and rotatable outer shaft, and vice versa.In addition, one skilled in the art will recognize that these application need not be confined to the x ray tube, and can be applicable to have any structure of the rotating member in the vacuum that this rotating member is by the liquid metal bearings.Therefore, no matter how construct or use, the present invention can be applicable to have any bearing construction of rotatable members and static component and the liquid metal between them.
In one embodiment, central shaft 41 comprises the radial projection 54 in the radial cavities 56 that is positioned at sleeve pipe 42, and sleeve pipe 42 can comprise the cover cap removed 58 that is configured to allow assembled component.Radial projection 54 limiting boots 42 are with respect to the axial motion of central shaft 41, and as shown in the figure, also comprise liquid metal 50 between radial projection 54 and the sleeve pipe 42 and between cover cap 58 and the central shaft 41.Radial projection 54 needn't be restricted on axial length, but the additional mechanical that can extend on axial length so that member to be provided supports.In one embodiment, radial projection 54 comprises herringbone (herringbone) or the spiral groove along axial surface 55.In another embodiment, radial projection 54 is extended on the whole axial length of the sleeve pipe 42 of bearing assembly 34.In this embodiment, radial projection 54 is cylindrical and be positioned in the cylindrical hole in the sleeve pipe 42.In one embodiment, central shaft 41 comprises and passes wherein and be configured to make cooling agent through wherein cavity 60.Cavity 60 can comprise the supply pipeline 62 that is positioned at wherein so that cooling agent 64 enters cavity 60 and leaves from it at outlet 68 places then at inlet 66 places.Therefore, cooling agent 64 makes the heat that produces from the anode 32 of x ray tube 4 can be extracted and be passed to the outside of x ray tube 4 from this.In one embodiment, bearing assembly 34 comprises removable end cap 69.
According to embodiments of the invention, central shaft 41, sleeve pipe 42, removable cover cap 58 and end cap 69 comprise location respective material or coating 70,72 thereon, with the corrosion of the base material that prevents them, thereby make it possible to use therein cheap base material.Such as will be discussed, material or coating 70,72 can be used as coating coating (for example among Fig. 3) or can be used as material or separately quote (for example among Fig. 4) as separated components.The exemplary parent metal that is used for central shaft 41, sleeve pipe 42, removable cover cap 58 and end cap 69 comprises refractory metal and alloy thereof,
(comprising material) based on nickel-cobalt iron containing alloy, (
Be the electric registered trade mark with manufacturing company (Westinghouse Electric and ManufacturingCompany) in room, Pennsylvania Pittsburgh city west), tool steel (the favorable mechanical processability is provided and has lower thermal conductivity), Maraging steel (not losing ductility and celebrated low-carbon (LC), superhigh intensity ferroalloy) to have outstanding intensity and toughness, iron-nickel (FeNi) alloy, superalloy and
(
Be the registered trade mark of Delaware State SCM metal product company (SCM MetalProducts Inc.)).In one embodiment, use and to have the iron-based matrix metal that is lower than 10% chromium content.In another embodiment, parent metal comprises 304 or 316 stainless steels.
Tantalum forms intermetallic compounds layer when contacting with gallium, but it should be understood that when comparing with molybdenum, and tantalum forms the much higher intermetallic compounds layer of high-temperature stability at elevated temperatures.According to one embodiment of present invention, therefore coating 70,72 contains tantalum.In another embodiment, tantalum can combine with another kind of material, for example can comprise the refractory metal of molybdenum or tungsten.According to embodiments of the invention, can (for example be called by mineralization, plating, chemical vapor deposition (CVD), physical vapor deposition (PVD), plasma strengthening PVD (PE-PVD), the laser reinforcing processing of fusing
Laser reinforcing be shaped only,
Be the registered trade mark of the Sandia company (Sandia Corporation) in Albuquerque, New Mexico city), cold injection, (cathode) sputtering and their combination be coated with application layer 70,72.Can be coated with application layer 70,72 with the thickness of selecting according to treatment conditions and expected result, yet each all has relative certain benefits.In one embodiment, as understanding in this area, can carry out mask, so that can coating 70 or coating 72 be coated to ad-hoc location by means of for example CVD to part to be coated.In another embodiment, can by means of for example CVD be coated with application layer 70,72 then in not wishing to have the zone of coating 70,72 by means of machine work or other known removal technology with its removal.
Still with reference to Fig. 3, in an embodiment of the present invention, coating makes it possible to carry out the coating 70,72 of later stage machine work or post-processed step thereon before the final assembling of bearing assembly 34.The post-processed step can be used with any amount of material removal technique well known in the art, for example machine work, acid etching, laser-induced thermal etching, electrochemistry processing etc.In this type of embodiment, coating 70,72 at first in the scope from 0.05mm to 0.15mm for example coating make groove form (for example because mechanical process) to occur in the coat layer rather than in parent metal to promote and to make it possible to carry out the later stage coating processing.Embodiments of the invention comprise also and are coated with application layer 70,72 to the degree of depth greater than 0.15mm that it also can comprise the later stage machining steps.In other words, coating or material are typically enough thick so that can rather than cut groove in parent metal in layer or coating 70,72.In addition, comprising that being coated with application layer 70,72 carries out among the embodiment of later stage machining steps then, persons skilled in the art will recognize that, can loosen the initial tolerances of base material, and the retrofit that the later stage machining steps can comprise higher tolerance to be removing for example surperficial aperture of 10-30 micron, thereby reduces processing cost by the part that allows to make lower tolerance before being coated with application layer 70,72.According to embodiments of the invention, the later stage machining steps is included in machine work spiral groove in the selected part of coating 70,72 as understanding in this area, so that provide swabbing action in SGB operating period liquid metal is maintained on the desired locations.According to an embodiment, spiral groove is worked in the coating 70,72 by means of electrochemistry processing (ECM).
In an embodiment, coating 70,72 is coated to up to 1mm or thicker thickness.This type of processing can comprise plasma spraying, fused salt deposition,
With cold injection.Because can be from these thickness of handle realizing, these be handled by making it possible to during the later stage machine work and cut groove and support according to later stage mechanical process of the present invention equally from coated material.For example, cold injection can be used for by utilizing Compressed Gas propelled at high velocity fine powder granules to be coated with application layer 70,72.These particles are colder, therefore to the bulk reaction (bulk reaction) of bump be in solid-state down, and oxidation is seldom or do not have an oxidation.Because these particles typically can not melt during handling, so less in the cooled shrinkage ratio of base material.Also can utilize the fused salt deposition that coating 70,72 is coated to enough thickness.This processing is included in the electrolytic deposition of tantalum in the molten salt mixture.In an embodiment of the present invention and as understanding in this area, salt mixture can comprise NaCl, KCl etc.Between depositional stage, as understanding in this area, part is typically comprised the source of refractory metal ion by cathodic polarization and fused salt.It will be appreciated that described processing just is used to apply the example according to coating of the present invention, and can adopt any amount of coating to handle to apply according to coating of the present invention.
Aforesaid other handled and be can be used for applying hierarchy according to an embodiment of the invention equally.In an example, wherein have the multilayer of the material of different weight percentage, can utilize CVD coating classification coating by coating.According to embodiments of the invention, as understanding in this area, any one in the above-mentioned processing that can apply coating with controlled mixture amount or layer can be used for coming by multilayer coated classification coating by the concentration that changes composition wherein equally.In addition, according to the present invention, one skilled in the art will recognize that coated classification coating not only can comprise two kinds of compositions, and can comprise that multiple composition is to apply any amount of coating.
Therefore, can be in hierarchical layer with different tantalum concentration coating material, it causes the change gradually on the thermal coefficient of expansion that runs through coating layer thickness.In this example, because the base material that the coating of close substrate surface has high concentration, so it has the thermal coefficient of expansion of the thermal coefficient of expansion that is similar to base material.Change of Class with the level that increases tantalum till realizing 100% tantalum coating on the outermost portion in coating.Therefore, thermal mismatching was minimized in adjoining on the part of coating, and Qi Wang outer surface has the tantalum coating simultaneously.
Electroplate and CVD can be used for applying have greater than the thickness of for example 0.1mm, for example thickness is 0.1mm to 2mm or bigger coating.This type of is handled typically by making it possible to and avoids base material simultaneously and carry out machine work and support the later stage mechanical process by cutting groove from coated coating fully.
According to embodiments of the invention, can apply the coating 70,72 that comprises tantalum, it has the base material kept at elevated temperatures to reduce the compressive residual stress under operating temperature in the coating during coating is handled.These class methods will make the more wide in range mismatch of the coefficient of expansion of material can be applied to following base material, thereby make it possible to select the base material and the coating material that differ from one another.In other words, this method has increased the selection that product attribute based on other expectation (for example but be not limited to thermal conductivity, thermal coefficient of expansion, intensity, toughness, cost (raw material and handle both) and welding performance/switching performance) makes up base material/coating.
In an embodiment of the present invention, coating is handled and can be combined.For example, though itself can't produce the coating layer thickness that is enough to support the later stage mechanical process PVD or PE-PVD, PVD/PE-PVD can combine with other processing and make it possible to carry out aforesaid low-cost processes and base material selection simultaneously with the adhesion that strengthens coating 70,72.For example, base material at first can have the coating by means of PVD or PE-PVD coating, then can be with the coating of second coating thereon by means of fused salt deposition for example, or for example by means of
The adhesion that can have improvement, so coating 70,72 can respectively comprise first adhesion layer and coated thereon second coating material.
According to another embodiment of the present invention, material 70,72 can from preferred auxiliary material or multiple auxiliary material preforming and by coating (cladding), brazing, shaped by fluid pressure, etc. static pressure, roll bond, rolling formation, mixing extruding, interference fit etc. invest on the base material.With reference to Fig. 4, bearing assembly 34 comprises central shaft 41, sleeve pipe 42, end cap 69 and cover cap 58.Among this embodiment, preformed member 74,76,78 and 80 is configured to be attached at as shown in Figure 4 on their corresponding members.For example, preformed member 74 is configured to be attached on the internal diameter 73 of sleeve pipe 42, preformed member 80 is configured to be attached on the external diameter 81 of central shaft 41, preformed member 78 is configured to be attached on the external diameter 83 of central shaft 41, and preformed member 76 is configured to be attached on the internal diameter 85 of removable cover cap 58.In one embodiment, preformed member 80 comprises material capped end 89, and in another embodiment, end cap 69 comprises the preforming material 69 that can be attached on the central shaft 41.
Although preformed member 74-80 is shown as by brazing on their corresponding bearing components, one skilled in the art will recognize that parts 74-80 can be combined or attached via any amount of attachment means (for example by welding, soldering etc.).In an embodiment of the present invention, the thickness of parts 74-80 is selected to the later stage machining steps can be carried out before assembling, and thickness is selected to and makes machine work, manipulation and brazing simple and be about 0.5mm or bigger.
With parts 74-80 as the material of coating attached after, parts 74-80 is carried out the later stage machine work with the thickness that obtains expectation, tolerance, surface quality etc., thereby obtains the final coating that in Fig. 3, is illustrated as coating 70,72.As shown therein, in optionally attached or bond material 82 was included in, it was used for parts 74-80 and 87 is attached at corresponding base material center sleeve 42, cover cap 58, central shaft 41 and end cap 69.And, although understand that the purposes of parts 74-80 is so that make it possible to assembled component, but one skilled in the art will recognize that according to the present invention and can adopt more or less parts, depend on the number of assembling steps of design and the cover expectation before brazing or otherwise attached these parts.
Therefore, according to embodiments of the invention, can come coating material or coating 70,72 (or parts 74-80 and 87 as shown in Figure 4) by means of the combination of a plurality of processing and processing.In an embodiment of the present invention, comprise that the material of tantalum or coating 70,72 can have enough thickness so that can carry out material or the later stage machine work of coating 70,72.Material or coating 70,72 can be used the suitable base material of special selection and coating material applies so that the thermal mismatching minimum between the member, maybe can be by applying so that residual stress minimum during operation handling itself to regulate.Can be based on the movement velocity of the life expectancy of coating, the corrosion that takes place in the tantalum when for example liquid gallium exists, the other factors of considering operating temperature simultaneously and influencing corrosion rate is selected coating layer thickness.In one embodiment of the invention, the final thickness of material or coating 70,72 greater than 0.1mm so that enough life-spans of bearing assembly 34 life period of 4 in the source to be provided.
Typically, tantalum can form oxide layer during handling and during being exposed to ambient oxygen, and this can reduce its surperficial wettability.The same with molybdenum, the part that scribbles tantalum can be by hydrogen burning to improve wettability.Yet, found that hydrogen burning becomes fragile tantalum.Therefore, according to one embodiment of present invention, another treatment step comprises and reduces on one or two coating 70,72 by plasma etching (that is, utilizing the ionization plasma gas) desired locations optionally or remove oxide layer.
Referring now to Fig. 5 and according to the above, technology 90 has illustrated the assembling of SGB bearing assembly (bearing assembly 34 as shown in Figure 3) according to an embodiment of the invention.Technology 90 starts from square frame 92, and at square frame 94 places assembling SGB part.For example, reference is about the described member of Fig. 3, and the SGB part of making at square frame 94 places includes but not limited to have for example bearing assembly 34 of central shaft 41, sleeve pipe 42 and removable cover cap 58.In addition, as described in about Fig. 3, bearing assembly 34 can change into and comprise other structure, includes but not limited to for example static external member and rotary middle spindle or straddles bearing.As described in about coating 70,72 in square frame 96 places coating tantalum coating.That is, part can have as the above coating that comprises tantalum 70,72 about coating as described in Fig. 3 and Fig. 4, have the embodiment (Fig. 3) of band to comprise, and comprise having the embodiment (Fig. 4) of band as the member of the material 70,72 of separated components coating as the member of the material 70,72 of coating coating.Part carries out post-processed at square frame 98 places.That is, as after being coated with application layer as described in about square frame 96, can carry out machine work, cleaning, measurement, test etc., to prepare assembling and to test as assembly to part.Post-processed at square frame 98 can comprise as above about Fig. 3 and described post-processed of Fig. 4 and later stage machine work.Alternatively, at square frame 100 places the part that scribbles tantalum is carried out the wettability of deoxygenation with raising coating 70,72, and in one embodiment, utilize plasma etching that part is carried out deoxygenation.At square frame 102 places assemblings bearing components 34, this assembling can comprise target is attached on one of SGB part, and member 34 be inserted in the assembly as described in for example Fig. 3 and Fig. 4 as above.At square frame 104 places and as known in the art liquid metal is coated on the bearing assembly 34.With reference to Fig. 3, for example, liquid metal 50 can be coated between the coating 70,72.In one embodiment, before the assembled component 34 liquid metal 50 is being coated on the member of bearing assembly 34, and among another embodiment, after assembled component 34, is applying liquid metal.In one embodiment, liquid metal 50 is gallium or its alloy.Technology 90 finishes at square frame 106 places.As understanding in this area,, just can further test, handle it and be manufactured in the device in x ray tube shown in Fig. 1 and Fig. 2 or source 4 in case assemble the SGB bearing assembly.
Therefore, because material or coating 70,72 have prevented that they are applied to the corrosion of the base material on it, selected base material can be cheap.And because the flexibility that material is selected, can select to have the base material of the engineering characteristic (such as but not limited to thermal conductivity, thermal coefficient of expansion, intensity, toughness, cost (raw material and handle both) and welding performance/binding ability) of improvement.
Fig. 6 is the diagrammatic sketch that is used for the x ray system 500 that uses with Noninvasive parcel detection system.X ray system 500 comprises saddle (gantry) 502, wherein has opening 504, and parcel or baggage item can pass through this opening.Saddle 502 holds such as the high frequency electromagnetic energy source of x ray tube 506 and detector assembly 508.The conveyer belt 512 that also provides transfer system 510 and it to comprise to support by structure 514 so that parcel or baggage item 516 be scanned through openings 504 automatically and continuously.Object 516 is fed by opening 504 by conveyer belt 512, obtains imaging data then, and conveyer belt 512 is removed parcel 516 in controlled and continuous mode from opening 504.Therefore, postal inspector, luggage operator and other Security Officers can check non-invasively whether the contents of parcel 516 are explosive, cutter, gun, prohibited items etc.Those of skill in the art can be appreciated that saddle 502 can be static or rotatable.Under the situation of rotatable saddle 502, system 500 can be configured to operate as the CT system that is used for luggage scanning or other industry or medical applications.
According to one embodiment of present invention, the x ray tube comprises negative electrode and the target assembly that is oriented to receive from the electronics of cathode emission.This target assembly comprises target and is configured to support the spiral groove bearing (SGB) of this target.This SGB comprises the rotating parts that has first surface and invest first material on the first surface; Have second surface and the static component that invests second material on the second surface, this static component is positioned such that the gap is formed between first material and second material; And be positioned in liquid metal in this gap, wherein at least one in first and second materials contains tantalum.
According to another embodiment of the present invention, target assembly comprises having the axle that invests first material on its outer surface; Be configured to support target and have the sleeve pipe that invests second material on its inner surface; And be positioned in liquid metal between first material and second material, wherein at least one in first and second materials contains tantalum.
According to another embodiment more of the present invention, the method that a kind of manufacturing is used for the target assembly of x ray tube comprises the steps: to provide the axle that has outer surface material and have external diameter; Sleeve pipe is provided, and this sleeve pipe has the aperture of the inner surface material that exposes sleeve pipe, and wherein the diameter of inner surface material is greater than the external diameter of outer surface material; Ground floor is coated on the inner surface material; And the second layer is coated on the outer surface material.This method comprises that also in the acid etching ground floor and the second layer at least one is to remove oxide from it, target is attached on one in axle and the sleeve pipe, axle is inserted sleeve pipe forming the pipe spreader assembly, and liquid metal is coated on one in the ground floor of pipe spreader assembly and the second layer.
This written description has used the example that comprises optimal mode to come open the present invention, and makes any technical staff of this area can implement the present invention, comprises the method for making and utilizing any device or system and carry out the combination of any institute.The present invention can obtain Patent right scope and be defined by the claims, and can comprise other example that those skilled in the art expect.If the described structural detail of word language that this type of other example is not different from claim; perhaps they comprise that the word language with claim does not have the equivalent structure element of essential distinction, think that then this type of other example is included in the protection range of claim.
Claims (8)
1. an x ray tube (4) comprising:
Negative electrode (36); And
Target assembly, it is positioned to receive the electronics from described cathode emission, and described target assembly comprises:
Target (32); And
Be configured to support the spiral groove bearing (SGB) (34) of described target (32), described SGB (34) comprising:
Rotatable members (42,58), first material (72,74,76) that it has first surface and invests described first surface;
Static component (41), second material (70,78,80) that it has second surface and invests described second surface, described static component (41) are located such that the gap is formed between described first material (72,74,76) and described second material (70,78,80); And
Be positioned at the liquid metal (50) in the described gap;
In wherein said first material and second material (70,72,74,76,78,80) at least one comprises tantalum.
2. x ray tube according to claim 1 (4) is characterized in that, one in described rotatable members (42,58) and the described static component (41) comprises one in 304 stainless steels and 316 stainless steels.
3. x ray tube according to claim 1 (4) is characterized in that, described static component (41) comprises that central shaft and described rotatable members (42,58) comprise sleeve pipe, and described sleeve pipe has the target (32) that is attached on it.
4. x ray tube according to claim 1 (4) is characterized in that, described SGB (34) also comprises:
The 3rd material (82), it is positioned between described rotatable members (42,58) and described first material (72,74,76); And
The 4th material (82), it is positioned between described static component (41) and described second material (70,78,80).
5. x ray tube according to claim 4 (4) is characterized in that, one in described the 3rd material (82) and described the 4th material (82) comprises brazing material.
6. x ray tube according to claim 1 (4) is characterized in that, described liquid metal (50) comprises one in the alloy of gallium and gallium.
7. x ray tube according to claim 1 (4) is characterized in that, one in described rotatable members (42,58) and the described static component (41) comprise refractory metal or refractory metal alloy, superalloy,
Tool steel, FeNi alloy, Maraging steel,
With one in the stainless steel.
8. x ray tube according to claim 1 (4) is characterized in that, one in described rotatable members (42,58) and the described static component (41) comprises having the iron that is lower than 10% chromium content.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US12/716,617 US8363787B2 (en) | 2009-03-25 | 2010-03-03 | Interface for liquid metal bearing and method of making same |
| US12/716617 | 2010-03-03 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN102194632A true CN102194632A (en) | 2011-09-21 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN2011100427624A Pending CN102194632A (en) | 2010-03-03 | 2011-02-15 | Interface for liquid metal bearing and manufacture method thereof |
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| CN (1) | CN102194632A (en) |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN106575592A (en) * | 2014-08-12 | 2017-04-19 | 皇家飞利浦有限公司 | Rotating anode and method for producing the rotating anode |
| US11017976B2 (en) * | 2018-07-09 | 2021-05-25 | General Electric Company | Spiral groove bearing assembly with minimized deflection |
| CN113270305A (en) * | 2021-05-26 | 2021-08-17 | 上海交通大学 | Liquid metal bearing |
| CN114429891A (en) * | 2021-12-28 | 2022-05-03 | 安徽理工大学 | Cooling device for medical CT machine bearing |
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| US5181235A (en) * | 1990-10-19 | 1993-01-19 | Kabushiki Kaisha Toshiba | Rotary-anode type x-ray tube |
| CN101290858A (en) * | 2007-04-20 | 2008-10-22 | 通用电气公司 | Soldering x ray tube target emission layer |
| WO2008148815A1 (en) * | 2007-06-04 | 2008-12-11 | Detection Technology Oy | Photodetector for imaging system |
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| US5181235A (en) * | 1990-10-19 | 1993-01-19 | Kabushiki Kaisha Toshiba | Rotary-anode type x-ray tube |
| CN101290858A (en) * | 2007-04-20 | 2008-10-22 | 通用电气公司 | Soldering x ray tube target emission layer |
| WO2008148815A1 (en) * | 2007-06-04 | 2008-12-11 | Detection Technology Oy | Photodetector for imaging system |
Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106575592A (en) * | 2014-08-12 | 2017-04-19 | 皇家飞利浦有限公司 | Rotating anode and method for producing the rotating anode |
| CN106575592B (en) * | 2014-08-12 | 2020-10-16 | 皇家飞利浦有限公司 | Rotary anode and method for producing a rotary anode |
| US11017976B2 (en) * | 2018-07-09 | 2021-05-25 | General Electric Company | Spiral groove bearing assembly with minimized deflection |
| US11037752B2 (en) * | 2018-07-09 | 2021-06-15 | General Electric Company | Spiral groove bearing assembly with minimized deflection |
| CN113270305A (en) * | 2021-05-26 | 2021-08-17 | 上海交通大学 | Liquid metal bearing |
| CN114429891A (en) * | 2021-12-28 | 2022-05-03 | 安徽理工大学 | Cooling device for medical CT machine bearing |
| CN114429891B (en) * | 2021-12-28 | 2024-01-30 | 安徽工程大学 | Cooling device for medical CT machine bearing |
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Application publication date: 20110921 |