Classifications

• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
  • H01J35/00—X-ray tubes
  • H01J35/02—Details
  • H01J35/04—Electrodes ; Mutual position thereof; Constructional adaptations therefor
  • H01J35/08—Anodes; Anti cathodes
  • H01J35/10—Rotary anodes; Arrangements for rotating anodes; Cooling rotary anodes
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
  • H01J35/00—X-ray tubes
  • H01J35/02—Details
  • H01J35/04—Electrodes ; Mutual position thereof; Constructional adaptations therefor
  • H01J35/08—Anodes; Anti cathodes
  • H01J35/10—Rotary anodes; Arrangements for rotating anodes; Cooling rotary anodes
  • H01J35/101—Arrangements for rotating anodes, e.g. supporting means, means for greasing, means for sealing the axle or means for shielding or protecting the driving
  • H01J35/1017—Bearings for rotating anodes
  • H01J35/104—Fluid bearings
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
  • H01J2235/00—X-ray tubes
  • H01J2235/08—Targets (anodes) and X-ray converters
  • H01J2235/081—Target material
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
  • H01J2235/00—X-ray tubes
  • H01J2235/08—Targets (anodes) and X-ray converters
  • H01J2235/086—Target geometry
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
  • H01J2235/00—X-ray tubes
  • H01J2235/10—Drive means for anode (target) substrate
  • H01J2235/1006—Supports or shafts for target or substrate
  • H01J2235/1013—Fixing to the target or substrate
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
  • H01J2235/00—X-ray tubes
  • H01J2235/10—Drive means for anode (target) substrate
  • H01J2235/1046—Bearings and bearing contact surfaces
  • H01J2235/106—Dynamic pressure bearings, e.g. helical groove type

Definitions

• the present invention relates to an X-ray rotating anode with an integrated liquid metal bearing outer shell according to the preamble of claim 1, an X-ray rotating anode system comprising an X-ray rotating anode with an integrated liquid metal bearing outer shell and a liquid metal bearing inner shell inserted therein, and also a manufacturing method of such an X-ray rotating anode.
• X-ray rotating anodes are used in X-ray tubes to generate X-rays.
• electrons are emitted from a cathode of the X-ray tube and accelerated in the form of a focused electron beam onto the rotating X-ray anode. Due to the rotational movement of the X-ray anode, an annular path - the focal path - is scanned by the electron beam. A large part of the energy of the electron beam is converted into heat in the X-ray rotating anode, while a small proportion is emitted as X-rays. The locally released amounts of heat lead to strong heating of the X-ray rotary anode. The rotation of the X-ray rotating anode counteracts overheating of the anode material.
• a high radiation output (or dose rate) is required, which can be generated by using a correspondingly high-energy and strongly focused electron beam.
• X-ray rotating anodes In order to avoid material fatigue due to high temperatures and temperature gradients, X-ray rotating anodes must be designed for high rotational frequencies and for effective and uniform heat dissipation. With regard to these requirements, the use of a liquid metal bearing for mounting the X-ray rotary anode is advantageous.
• the object of the present invention is to improve X-ray rotating anodes with regard to good storage at high rotational frequencies and uniform and effective heat dissipation. Furthermore, a cost-effective and process-stable production of the X-ray rotary anode is to be made possible.
• an X-ray rotary anode with an integrated liquid metal bearing outer shell has an anode disk made of Mo (Mo: molybdenum) or a Mo-based alloy with a hole formed centrally in the area of the axis of rotation and extending in the axial direction through at least part of the anode disk and a bearing bush made of Mo or a Mo-based alloy.
• the inner wall of the bearing bush is at least over an axial section of the same circumferentially (ie in the circumferential direction based on the axis of rotation) designed as a liquid metal bearing running surface and forms a first section of the liquid metal bearing outer shell.
• the entire (typically cylindrical) inner wall of the bearing bush can be designed as a liquid metal bearing running surface.
• only an axial section of the inner wall of the bearing bush, which is then also typically cylindrical, can be designed as a liquid metal bearing running surface, while a further axial section, for example, also includes mechanical limiting elements and / or a coating through which liquid metal is used in use Liquid metal bearing is retained, may have.
• the liquid metal bearing outer shell is formed by the first and an adjoining second partial section and has a continuous liquid metal bearing running surface. The bearing bush is in such a way a cohesive one Connection connected to the anode disk that the inner wall of the bearing sleeve continues the hole of the anode disk.
• At least one axial section of an inner wall of the hole of the anode disk is designed as a liquid metal bearing running surface circumferentially (ie in the circumferential direction with respect to the axis of rotation) and forms at least part of the second section of the liquid metal bearing outer shell.
• the entire (typically cylindrical) inner wall of the hole can again be designed circumferentially as a liquid metal bearing running surface.
• the bottom of the hole can optionally also form a liquid metal bearing running surface.
• only an axial section of the inner wall of the hole, which is then also typically cylindrical, can be designed circumferentially as a liquid metal bearing running surface.
• a defined bearing gap is formed between a liquid metal bearing outer shell and a liquid metal bearing inner shell, which are matched to one another and of which one is formed on a stationary component and one on a rotating component.
• the liquid metal bearing outer shell is designed integrally with the X-ray rotating anode and thus as a rotating component.
• the liquid metal bearing inner shell can, for example, be formed integrally on a pin (stationary component) introduced into the liquid metal bearing outer shell.
• the bearing gap is filled with liquid metal (eg gallium, a gallium alloy such as a eutectic gallium-indium-tin alloy, etc.).
• the gap width is typically from a few micrometers up to 500 ⁇ m (at least ⁇ 1 mm); in particular from 5-500 ⁇ m, preferably from 7-40 ⁇ m, the gap width also being able to vary over the length of the bearing gap.
• at least one circumferential recess and / or step or rib can also be provided in the liquid metal bearing outer shell and / or inner shell, in the area of which the gap width can also differ from the rest of the bearing gap (see e.g. DE 102015215306 A1).
• at least one circumferential rib on the one component with (at least) one correspondingly formed channel on the other component for fixing the two components relative to one another in the axial direction can be provided.
• Used as liquid metal bearing treads denotes the sections of the liquid metal bearing outer shell and the liquid metal bearing inner shell, which are wetted with liquid metal in use both on the liquid metal bearing outer shell and on the liquid metal bearing inner shell and thus enable low-friction rotation.
• the liquid metal prevents direct contact between the liquid metal bearing outer shell and the liquid metal bearing inner shell and at the same time acts as a lubricant, whereby excellent running properties are achieved.
• the liquid metal bearing outer shell is provided with a rotor or is (mechanically) coupled to it, which is set in rotation in a known manner in cooperation with a stator.
• liquid metal bearing to support the X-ray rotary anode is advantageous, since liquid metal bearings are designed for a high load and for high rotational frequencies and at the same time have a high level of operational reliability and a long service life.
• One advantage (for example compared to a ball bearing) is that the increased pressure of the liquid metal located in the bearing gap is formed over a larger surface section (especially in the axial extension) and thus the mechanical stability is increased.
• rotational frequencies of up to 300 Hz (Hertz) are possible with liquid metal bearings, while ball bearings, for example, are usually designed for rotational frequencies well below 200 Hz (eg 140 Hz).
• liquid metal bearings are low-noise compared to ball bearings and enable effective and large-area heat dissipation due to the enlarged contact surface (via the bearing gap filled with liquid metal).
• the heat can be effectively dissipated to the stationary component (eg to a pin inserted on the inside of the liquid metal bearing outer shell).
• the heat can then be effectively removed from the stationary component via internal cooling (by means of a coolant guided in at least one cooling channel), so that the thermal management is very effective and therefore suitable for the high-performance area.
• Ball bearings are not designed for effective heat dissipation via the bearing due to the heat-sensitive coatings used, as this would damage the respective coating.
• Mo or Mo-based alloys are particularly advantageous as material for the anode disk and for the bearing bush, since they have a high level of strength (even at the high operating temperatures) and enable good heat dissipation. Furthermore, Mo or Mo-based alloys have good wettability for the liquid metals typically used. Accordingly, it is also advantageous that the inner wall of the bearing bushing as well as the inner wall of the hole in the anode disk are designed as a liquid metal bearing running surface, since the base material already provides good wettability. Optionally, a coating (typically less than 10 ⁇ m thick) can be provided on the inner wall of the bearing bush and / or on the inner wall of the hole - in each case completely or only in sections.
• a Mo-based alloy is understood to mean an alloy which contains> 50% by weight of Mo. In particular, it contains> 80% by weight, even more preferably> 98% by weight, Mo, which is particularly advantageous in view of the properties of Mo mentioned above.
• the anode disk and the bearing sleeve do not have to be made entirely of Mo or a Mo-based alloy, but rather the base material is referred to here in particular. In particular, they can have a coating (e.g. a blackening layer to increase the radiated heat output), add-on parts, such as a C-based body attached to the anode disk as a heat storage device (e.g.
• the “focal path” is the section of the anode disk that runs in a ring around the axis of rotation and that is scanned by the electron beam during use.
• a focal path coating is applied to the anode disk in the area of the focal path (with a certain radial extent).
• the focal path coating is formed in particular by W or a W-Re alloy with a Re content of 1-15% by weight, in particular 5-10% by weight (W: tungsten; Re: rhenium).
• the anode disk typically has an angled focal path surface, which preferably forms a circumferential truncated cone jacket surface.
• the focal path surface is angled relative to a reference plane extending perpendicular to the axis of rotation, whereby the exit of the generated X-ray radiation is made possible through a laterally located exit window of the respective X-ray device.
• it forms a focal path angle in the range of 2 ° -16.25 °, in particular 7 ° -13 ° relative to this reference plane.
• the “axis of rotation” referred to is given by the rotationally symmetrical basic shape of the X-ray rotating anode and the liquid metal bearing outer shell.
• the axis of rotation simultaneously specifies the “axial direction” (running parallel to this) and the “radial direction” (running perpendicular to this).
• a “reference plane” of the X-ray rotating anode (which typically forms its main plane of extent at the same time) extends in particular perpendicular to the axis of rotation. It should be noted that the X-ray rotating anode does not have to be designed to be rotationally symmetrical in every detail, so that, for example, slots formed in the circumferential direction, periodically arranged projections, depressions, attachments, etc., can break through an exact rotational symmetry.
• a bearing bush is a component with a (through) hole, the inner wall of which is at least partially designed as a liquid metal bearing running surface, wherein the bearing bush can have different (especially outside) contours and attachments.
• the bearing bush (and correspondingly the mechanical mounting of the X-ray anode) is arranged on the opposite side of the anode disk from the focal path.
• the Bearing bush (and correspondingly the mechanical holder of the X-ray rotary anode) can also be arranged on the side of the anode disk on which the focal path is provided.
• the first section of the liquid metal bearing outer shell is monolithic with the bearing bush and at least part of the second section of the liquid metal bearing outer shell is monolithic with the anode disk.
• “Monolithic” means that the component in question is manufactured in one piece as part of the metallurgical production (preferably powder metallurgy or alternatively melt metallurgy), with subsequent mechanical processing, for example to make the hole and / or surface structuring, and / or a subsequent application of at least one layer is possible.
• a monolithic design can be recognized by the person skilled in the art on the basis of a uniform and continuous microstructure (the base material made of Mo or a Mo-based alloy).
• a powder-metallurgical production of the anode disk and / or the bearing bushing is preferred, this comprising the steps of pressing and sintering corresponding starting powders and preferably a subsequent reshaping (e.g. rolling, forging, extrusion, etc.) of the molded body obtained.
• Powder metallurgical production leads to a typical microstructure recognizable to the person skilled in the art, which can be clearly distinguished from a melt structure (obtained in the context of melt metallurgical production), for example.
• the inner wall of the bearing bush is made from the base material (Mo or Mo-based alloy) of the bearing bush, at least in the area of the liquid metal bearing running surface, and the inner wall of the hole in the anode disk is made of at least in the area of the liquid metal bearing running surface the base material (Mo or Mo-based alloy) of the anode disk.
• a coating typically less than 10 ⁇ m thick
• a surface structuring can also be provided on the inner wall of the bearing bush and / or on the inner wall of the hole in the anode disk.
• a material connection is understood to mean that a continuous material composite is created, but not that only a mechanical one Attachment (e.g. via a screw or clamp connection, via mechanical fastening elements, etc.).
• the stoffschlüssi ge connection of the bearing bush and the anode disk is made by welding, soldering or diffusion bonding (diffusion connection). If the connection zone is examined microscopically in the section, a welded connection is to be determined by the expert through a corresponding welding zone (melted or at least plasticized base material), a soldered connection through a corresponding soldering zone (melt structure of the solder) and a diffusion connection through a corresponding diffusion zone (diffusion area of the interconnected basic materials).
• liquid metal bearing outer shell is recognizable to the expert on the basis of the shape, in particular based on the liquid metal bearing running surface formed on the inside rotationally symmetrical to the axis of rotation and the inner contour, which enables the introduction of a pin (or other component) with a corresponding liquid metal bearing inner shell. Furthermore, no tread for a ball bearing is provided on the inner contour (even if the liquid metal bearing tread can basically be stepped and / or be provided with a rib or a recess).
• a surface structuring, a coating and / or mechanical delimitation elements for retaining the liquid metal in the area of the liquid metal bearing are provided in the area of the end sections of the liquid metal bearing outer shell and / or a liquid metal bearing inner shell.
• the material connection is a connection produced via diffusion bonding, a friction weld connection or a beam weld connection (with a laser or electron beam).
• the advantage of the connection techniques mentioned is that a material connection with high strength can be achieved with them, even at the high operating temperatures.
• an additional material such as solder, welding filler material, etc.
• solder, welding filler material, etc. which can form a disruptive contamination (e.g. of the liquid metal) in the area of the liquid metal store, can be critical for vacuum stability (use takes place in a high vacuum) and / or a lower melting point (compared to the base material the connected components) can be dispensed with.
• This is particularly advantageous compared to a soldered connection in which the solder typically has a lower melting point and - at least at high temperatures - has a lower strength than the base material (of the connected components).
• diffusion bonding the (typically appropriately prepared) surfaces of the components to be connected are joined together and the application of pressure and temperature causes diffusion of the atoms in the area of the connection zone, resulting in a bonded connection (diffusion connection).
• diffusion connection there is no melting of the base material of the components to be connected in the area of the connection zone.
• a diffusion connection can be recognized by a person skilled in the art by microscopic examination of the connection zone in the micrograph using a corresponding diffusion zone (diffusion area of the basic materials connected to one another) in which no melt structure occurs.
• the diffusion connection may not be visible in the microscopic micrograph, since a uniform structure that is continuous with the respective base material can be achieved in the area of the connection zone.
• the existence of a diffusion connection can only be deduced from the outer geometry of the connected components (in this case: anode disk and bearing bush), for example because they could not be produced in one piece (e.g. powder metallurgy) in the respective overall form.
• a beam welded connection can be recognized by a specialist on the basis of a microscopic examination of the connection zone in the micrograph based on the welding zone in which a corresponding melt structure (of the base materials and, if necessary, an additional welding filler material) occurs, as well as at the root and the location of the melt zone .
• a beam welding connection (in particular by means of electron beam welding) is advantageous due to the small heat-affected zone. Furthermore, the beam welding process is better suited for Mo-based alloys than for pure molybdenum.
• friction welding a component is moved (eg rotated) relative to and in contact with the other component to be joined in order to generate heat at the joint surfaces.
• the weld is completed by applying a force during or after the removal of the relative movement (eg rotational movement), whereby there are several forms of energy supply and relative movement.
• a force during or after the removal of the relative movement (eg rotational movement), whereby there are several forms of energy supply and relative movement.
• Friction welding which also enables the connection of components with thicker walls (in particular 20-130 mm), only requires a comparatively low joining temperature in the joint cross-section and is therefore suitable in many cases for materials and material combinations that are otherwise difficult to weld (cf. . also DIN EN ISO 15620).
• a friction-welded connection can be recognized by a person skilled in the art from a microscopic examination of the connection zone in the micrograph based on a typical microstructure. In particular, no melt structure can be seen, since the base material is only put into a plasticized state during friction welding.
• the welding zone is typically comparatively narrow and has a fine-grain structure.
• the grains are stretched in the direction of the material flow, which takes place in particular when the weld bead is formed. Zones of different grain stretching (with high grain stretching close to the bearing bush and lower grain stretching near the anode disk) occur in particular when the bearing bushing has a high grain stretching and the anode disk has a lower grain stretching, which is imprinted on these components by their respective manufacturing process. Macroscopically, it also indicates a friction-welded connection when a on the anode disk projecting connection piece is used to enable the formation of a weld bead during friction welding (due to the flow of material during the upsetting phase). This can be seen in particular from a weld zone spaced apart from the anode disk between the connection piece and the bearing bush.
• the Mo-based alloy (s) (of the anode disk and / or the bearing bush) is / are MHC and / or TZM.
• the base material of the bearing bush i.e. apart from coatings, add-on components, etc.
• the base material of the anode disk i.e. apart from coatings, attachments, etc.
• the base material of the anode disk is made of MHC and / or TZM (preferably only MHC or only TZM). Both alloys (MHC, TZM) have high strength and hardness.
• MHC has mechanical properties largely retained at high temperatures, which means that higher process temperatures during manufacture and higher operating temperatures for the X-ray rotary anode are possible. This is especially true for MHC for temperatures up to 1250 ° C and for TZM up to 1100 ° C. MHC is therefore particularly well suited for the high-performance area and for high operating temperatures.
• MHC is a Mo-based alloy offered by the applicant Plansee SE, which has the following composition:
• TZM is a Mo-based alloy specified in the ASTM B387 (364) standard and offered by the applicant Plansee SE, which has the following composition for the present application:
• any impurities that may be present is typically not specified for all elements, but in particular for those that are typically included and / or for which too high a content would be critical for the advantageous properties of the alloy.
• the following permissible ranges of impurities are particularly advantageous:
• the content of metallic impurities in MHC and TZM is ⁇ 5000 pg / g in total.
• the content of Al (aluminum) and Ni (nickel) is ⁇ 10 pg / g, the content of Cr (chromium), Cu (copper), Fe (iron) ), K (potassium), and Si (silicon) each ⁇ 20 pg / g, the content of W (tungsten) ⁇ 300 pg / g, the content of Cd (cadmium) and Pb (lead) each ⁇ 5 pg / g and the content of Hg (mercury) ⁇ 1 pg / g.
• the total content of any impurities caused by H (hydrogen), N (nitrogen) and O (oxygen) at MHC is ⁇ 1000 pg / g.
• the H and N content is ⁇ 10 pg / g and the O content is ⁇ 600 pg / g.
• the total amount of impurities caused by H, N, O and C (carbon) at TZM is ⁇ 1500 pg / g.
• the H and N content is ⁇ 10 pg / g and the O content is ⁇ 500 pg / g.
• the anode disk and the bearing bush can be made from different materials. According to a further development, the anode disk and the bearing bush are both formed from molybdenum or both from the same molybdenum-based alloy.
• the material connection is a friction weld connection.
• friction welding technology has a high degree of reproducibility and a high degree of automation.
• an additional material such as a welding filler material, an insert inserted between the components to be connected, etc.
• Mo-based alloys are preferred over pure Mo for friction welding.
• the two components are made from the same Mo-based alloy (e.g.
• the anode disk on the side of the bearing sleeve to a connecting piece which extends the hole of the anode disk with its inner wall and protrudes opposite the outer surface of the anode disk.
• At least one axial section of the inner wall of the connecting piece is circumferentially designed as a liquid metal bearing tread and forms (in addition to the inner wall of the hole in the anodic disk and possibly other sections) part of the second Operaabschnit tes of the liquid metal bearing outer shell.
• the integral connection between the protruding connection piece of the anode disk and the bearing bushing is formed.
• the material connection between the anode disk and the bearing bush can be produced more easily.
• the integral connection is thus spaced from the outside surrounding surface of the anode disk, for example by 2-50 mm, preferably by 5-30 mm (areas apply to the finished integral connection).
• the connecting piece is preferably designed monolithically with the anode disk, which is advantageous in terms of stability and running properties.
• the connecting piece is preferably formed monolithically from the material of the anode disk as part of a forging process. Alternatively, it can also be firmly bonded to the anode disk.
• the hole of the anode disk is designed as a through hole and the anode disk has an extension piece opposite from the side of the bearing bushing, the inner wall of which extends the through hole of the anode disk and which protrudes from the outside surrounding surface of the anode disk.
• At least one axial section of the inner wall of the extension piece is circumferentially designed as a liquid metal bearing running surface and forms part of the second section of the liquid metal bearing outer shell (in addition to the inner wall of the hole in the anode disk, possibly the connecting piece and possibly other sections).
• the extension piece can also preferably be designed monolithically with the anode disk (e.g. formed by forging) or alternatively be connected to the anode disk in a materially bonded manner.
• the extension piece and any further components that may be present then preferably form the closure of the liquid metal bearing outer shell.
• another bearing bush can be firmly connected to the extension piece and thus extend the liquid metal bearing outer shell even further, with the variants described here for connecting the connecting piece to the bearing bush are also possible.
• the thickness (measured in the axial direction) of the anode disk increases in the radial direction towards the axis of rotation.
• This thickness can take place continuously (with a constant slope or with a varying thickness profile) or in one or more stages.
• the heat generated in the area of the focal path can be divided towards the axis of rotation over an increasingly larger material cross-section and then effectively over the large area of the liquid metal bearing outer shell (over the liquid metal arranged in the bearing gap and then over the liquid metal bearing inner shell and the adjoining components , for example via a pin with coolant cooling).
• the increase in thickness starting from a reference thickness measured radially in the center in the area of a beveled focal path surface up to the thickness in the area of the hole, is 30-300%, in particular 50-260%, even more preferably 70-230% (an increase in thickness of 100 % corresponds to a doubling of the thickness). This is particularly advantageous with regard to heat dissipation and also with regard to the stability and running properties of the liquid metal bearing outer shell.
• Thickness in the area of the hole is the thickness of the anode disk directly in the area of the inner wall of the hole, with this thickness measurement also possibly monolithically formed with the anode disk, such as a monolithically formed connecting piece and / or a monolithically formed Extension stubs, are included, but not only components that are firmly bonded to the anode disk (e.g. the bearing bush).
• the anode disk also increases in thickness radially inwardly without the inclusion of the possibly monolithically designed connecting stubs and / or extension stubs.
• the latter increase in thickness is 20-150%, preferably 30-100%, with the provision of a monolithic connecting and / or extension piece instead of the “area of the hole” a directly (radially) outside of this connection and / or extension piece Reference range is used.
• the anode disk has several evenly arranged circumferentially and through the thickness of the anode disk.
• existing slots each of which extends over a radial section in the region between an outer circumference of the anode disk and the hole of the anode disk.
• Such slots enable the material of the anode disk to be stretched during use at the increased temperatures occurring without it being plastically deformed, as a result of which stresses within the material and thus material fatigue or material failure are avoided.
• Such slots can extend exactly radially. Alternatively, however, they can also run slightly obliquely to the radial direction (for example at an angle of> 0 ° up to 5 °).
• end bores which preferably extend through the thickness of the anode disk and each have a larger diameter than the width of the opening slots, and / or a circumferential channel can be provided be.
• the slots extend all the way to theassium catch, ie open into the outer circumference, while they end radially outside of the hole in the anode disk.
• all slots are symmetrical to each other with respect to the axis of rotation. The provision of such slots is particularly advantageous when the thickness of the anode disk increases towards the axis of rotation.
• the present invention also relates to an X-ray rotary anode system comprising an X-ray rotary anode according to the invention with an integrated liquid metal bearing outer shell, which can optionally also be designed according to one or more of the developments explained above, as well as a liquid metal bearing inner shell inserted into the liquid metal bearing outer shell, which has a liquid metal bearing running surface, the liquid metal bearing outer shell and the liquid metal bearing inner shell being matched to one another in such a way that a defined bearing gap is formed between them (gap width in particular as indicated above).
• At least one circumferential mechanical limiting element is provided in the area of at least one axial end section (axial: based on the axis of rotation) of the liquid metal bearing running surface on the liquid metal bearing outer shell and / or the liquid metal bearing running surface on the liquid metal bearing inner shell, which in use, a flow of liquid metal located in the bearing gap is limited in the axial direction.
• the mechanical limiting element consequently serves to retain the liquid metal in the (axially) inner region of the liquid metal bearing, where it is required to achieve the sliding effect.
• the mechanical limiting element can in particular be formed by one or more of the following variants:
• a sealing ring made of a material (e.g. an alloy containing iron, nickel and cobalt) that interacts with the liquid metal located in the bearing gap (see e.g. DE 10 2015204488 A1).
• a material e.g. an alloy containing iron, nickel and cobalt
• a circumferential coating is provided in the area of at least one axial end section of the liquid metal bearing running surface on the liquid metal bearing outer shell and / or the liquid metal bearing running surface on the liquid metal bearing inner shell, which wetting through the in use in the Liquid metal located in the bearing gap is suppressed.
• the liquid metal is held back in the (axially) inner area of the liquid metal bearing, where it is required to achieve the sliding effect.
• Suitable coatings include titanium oxides, aluminum oxides, titanium nitrides and mixtures thereof, in particular CrN (chromium nitride), Cr2N (dichromium nitride), Cr203 (chromium (III) oxide), TiAlN (titanium aluminum nitride) (cf. eg US 2017/0169984 A1).
• the coating can be provided both on the liquid metal bearing inner shell and on the liquid metal bearing outer shell. If necessary, however, it can also be provided on only one (for example only on the inner shell of the liquid metal bearing). Furthermore, it can also be provided in the area of at least one mechanical limiting element.
• the inner shell of the liquid metal bearing is formed on a pin which is guided through the bearing bush at least into the hole in the anode disk.
• the pin preferably has at least one coolant channel for guiding coolant. If the hole is designed as a through hole, the pin preferably also extends completely through this through hole.
• the pin can preferably be formed from one component (in one piece), since this is advantageous with regard to its stability and the tightness of the coolant channel. Alternatively, it can also be formed from several components that are positively and / or cohesively connected to one another, which can be advantageous in particular in the case of a complex structure of the liquid metal bearing.
• the heat can be effectively dissipated during use through the at least one coolant channel, which preferably extends over at least 80% of the length of the pin.
• the liquid metal bearing running surface on the liquid metal bearing outer shell and / or the liquid metal bearing running surface on the liquid metal bearing inner shell has at least two circumferential, surface-structured running sections which are spaced apart from one another in the axial direction.
• at least one section without superficial structuring is provided between the at least two superficially structured running sections.
• the rotating component rotates, liquid metal collects and forms an increased pressure. This achieves a particularly good sliding effect.
• the rotating and static components are fixed relative to one another in the radial direction.
• a superficially structured running section is formed in an area completely arranged within the anode disk or is at least formed to overlap with this area.
• the superficial structuring can, for example, be designed as a grooved pattern (having, for example, one or more subregions, each with grooves running parallel to one another).
• the superficially structured running sections can in principle be provided both on the liquid metal bearing inner shell and on the outer shell. In principle, running sections structured on the surface can also be formed opposite one another (in relation to the bearing gap). However, it is preferred that in the area of a superficially structured running section of one component (for example on the liquid metal bearing inner shell) the other component in the opposite area does not have a superficially structured running section.
• the present invention also relates to a method for producing an X-ray rotary anode according to the invention, which can optionally also be designed according to one or more of the developments and variants explained above, the method having the following steps:
• the method creates a cost-effective and reliable manufacturing route for manufacturing X-ray rotating anodes according to the invention. Furthermore, the Further developments and variants explained above are also possible in the method according to the invention by providing corresponding method steps, the advantages explained above being achieved.
• the anode disk and / or the stump are preferably provided as part of a powder-metallurgical production. This includes, in particular, the pressing and sintering of the corresponding starting powder, preferably also forming (e.g. rolling, forging, round rolling, round forging, etc.).
• a hole in the anode disk and / or a through hole in the bearing bush can already be preformed before the material connection, so that mechanical reworking is less complex. Alternatively, they can also be worked out in the course of mechanical processing (i.e. the anode disk and / or the stump do not have a hole or through hole before the material connection).
• the material connection is preferably carried out by friction welding.
• a focal path coating can already be applied to the anode disk prior to the material connection (e.g. in the context of a powder metallurgical production in the composite), but it can also be applied afterwards, e.g. by thermal spraying (e.g. vacuum plasma spraying), by chemical vapor deposition (CVD: Chemical vapor deposition) or by physical vapor deposition (PVD: physical vapor deposition).
• thermal spraying e.g. vacuum plasma spraying
• CVD chemical vapor deposition
• PVD physical vapor deposition
• FIG. 1 A perspective view of an X-ray rotating anode according to the invention in cross section according to a first embodiment
• 2A, 2B two cross-sectional views of the X-ray rotary anode from FIG. 1 to illustrate the manufacture
• 3 a cross-sectional view of an X-ray rotary anode according to the invention according to a second embodiment
• 4 a cross-sectional view of an X-ray rotary anode according to the invention according to a third embodiment
• 5 a cross-sectional view of an X-ray rotary anode according to the invention according to a fourth embodiment
• 6 a cross-sectional view of an X-ray rotary anode according to the invention according to a fifth embodiment
• 7 a cross-sectional view of an X-ray rotary anode according to the invention according to a sixth embodiment
• FIG. 8 a cross-sectional view of an X-ray rotary anode according to the invention according to a seventh embodiment
• FIG. 9 a cross-sectional view of an X-ray rotary anode system according to the invention with inserted peg, two variants A and B of the peg being shown above the cross-sectional view, each in a plan view and a cross-sectional view.
• JP 2012/084400 A and US 2017/0169984 A1 are shown. That is, in the representations of FIGS. 1-9, the bearing bush, the anode disk and the pin can also continue in the axial direction - with a possibly different course or different configuration - and / or be connected to other components .
• FIGS. 1 and 2A, 2B A first embodiment of an X-ray rotary anode 2 according to the invention is explained below with reference to FIGS. 1 and 2A, 2B.
• This has a rotationally symmetrical in its basic shape to an axis of rotation 4 (axial direction) trained anode disk 5 made of MHC.
• On one side of the anode disk 5 there is a circumferential focal path 6 with a focal path coating made of a W-Re alloy (W: 95% by weight; Re: 5% by weight).
• W-Re alloy W: 95% by weight
• Re Re: 5% by weight
• the anode disk 5 has a circumferential beveled focal path surface 10 which is angled relative to a reference plane 8 extending perpendicular to the axis of rotation 4 (at an angle a).
• a hole 12 the inner wall 14 of which is designed as a liquid metal bearing running surface, extends through the anode disk 5.
• the anode disk Opposite from the side of the focal path 6, the anode disk has a monolithic, tubular connec tion stub 16 forged on from the material of the anode disk 5, which protrudes from the surface of the anode disk 5 surrounding the outside.
• Its inner wall 18 extends the hole 12 of the anode disk 5 and is also thoroughlybil det as a liquid metal bearing tread.
• a tubular bearing bush 20, which is also made of MHC, is connected with its axial (annular) end face via a cohesive connec tion 21 with the correspondingly designed, axial (annular) end face of the connecting piece 16.
• the inner wall 22 of the bearing bush 20 is designed circumferentially as a liquid metal bearing running surface.
• the liquid metal bearing running surfaces of the anode disk 5, the connecting piece 16 and the bearing bush 20 jointly form a continuous liquid metal bearing running surface which in the present case extends linearly in the form of a cylinder jacket surface and which forms part of a liquid metal bearing outer shell.
• the bearing sleeve 20 and the anode disk 5 are still shown as separate components and finally in Fig. 2B after the establishment of the integral connection 21 via friction welding (and mechanical reworking). As explained, the friction welding leads to a shortening of the connec tion stub 16 and the bearing bush 20 in the area of the connection zone in the axial direction.
• the thickness of the anode disk 5 'radially inward continuously increases starting from a reference thickness dR (measured radially in the middle in the area of the beveled focal path surface 10) up to the maximum thickness du in the area of the hole 12 (including all components monolithically connected to the anode disk 5 ', ie the present Connecting piece 16) by 30-300%. Furthermore, starting from the reference thickness dR, the thickness increases radially inward by 20-150% even without including the monolithically formed connecting piece 16, the thickness di in the inner area then being measured directly (radially) outside of the connecting piece 16.
• the anode disk 5 has - in comparison to the first embodiment - on the side opposite the bearing bush 20 an extension connector 24 which, with its inner wall 26, the (through) hole 12 of the anode disk 5 extended and opposite to the outside surrounding surface of the anode disk 5 is in front.
• the inner wall 26 of the extension piece 24 is also designed all around as a liquid metal bearing running surface and thus forms part of the liquid metal bearing outer shell.
• the increase in thickness starting from the reference thickness dR up to the maximum thickness du is shown in FIG.
• the anode disk 5 ′′ - in comparison to the first embodiment - has no connecting stub. Rather, the bearing bush 20 is connected directly to the planar surface of the anode disk 5 ′′ via a diffusion connection.
• the bearing bush 20 is arranged on the same side as the focal path 6.
• the connecting piece 16 ′ on the anode disk 5 ′ ′′ is also arranged on the side of the focal path 6.
• the anode disk 5 ′′ - similar to the fourth embodiment (see FIG. 5) - has no connecting stub. Rather, the bearing bush 20 is over a diffusion connection is connected directly to the planar surface of the anode disk 5 ".
• the seventh embodiment shown in FIG. 8 differs from the sixth embodiment in that the thickness of the anode disk 5 ′′ continuously increases radially inward.
• an X-ray rotary anode system 27 is shown in which the X-ray rotary anode 2 with anode disk 5 ‘′′, connecting piece 16‘ and bearing bushing 20 is designed as in the fifth embodiment (cf. FIG. 6). Also shown is a pin 28 inserted on the inside, on which the liquid metal bearing inner shell is formed. A bearing gap 30 is formed between the liquid metal bearing inner shell of the journal 28 and the liquid metal bearing outer shell, which is filled with liquid metal (not shown) during use.
• Two exemplary variants for the design of the pin 28 are shown above the X-ray rotating anode. According to the first variant A (shown above in FIG.
• the pin 28 has a tubular basic shape and a smooth surface on the outside.
• the pin 28 ‘has two superficially structured and axially spaced running sections 32, 34.
• the pin 28 ' also has a coolant channel 36 running on the inside, which has a coolant tube 40 inserted into a blind hole 38, the diameter of the coolant tube 40 being selected to be correspondingly smaller than that of the blind hole 38, so that coolant flows in via the coolant tube 40, for example can flow back on the outside via the annular channel formed between the coolant tube 40 and the blind hole 38.
• the anode disk and a stump are using cylindrical basic shape produced by powder metallurgy, which includes the steps of providing the appropriate starting powder (for MHC), pressing and sintering, as well as in the present case a subsequent forming (forging the anode disk; radial forging the stump).
• the stump is mechanically processed so that it has a tubular basic shape in order to form the later bearing bush.
• a protruding tubular connection piece (with an axial length of 40 mm) is forged on the anode disk centrally on one side, ie the connection piece is formed monolithically from the material of the anode disk.
• Both the end face of the tubular stump and the end face of the connecting piece have an area to be welded of 2,000 mm 2 and an inside diameter of 44 mm (the outside diameter is determined by this).
• a friction welding machine with direct spindle drive is used. The tubular stump is clamped into the (non-rotating) holder of the friction welding machine and the anode disk is clamped into the (rotating) spindle holder.
• the anode disk is then set in rotation (2,000 revolutions per minute) and pressed against the stump with a friction pressure of 30 bar. Then the drive of the anode disk is stopped and the upsetting pressure is increased to 65 bar. The total friction time, ie within which a relative rotational movement takes place between the anode disk and the stump, is 3 seconds.
• Mechanical processing then follows to produce the final geometry, the tubular stump then forming the bearing bush. Other add-on parts, coatings, coverings, etc. can be added - as explained at the beginning.
• stress relief annealing e.g. at temperatures in the range of 1,100 ° C - 1,300 ° C
• stress relief annealing can be inserted once or several times during the manufacturing process,
• Example 2 In the following, a production method of an X-ray rotary anode according to the invention is described, in which the anode disk and the bearing bush are made from TZM and are connected to one another by friction welding. The same steps and parameters are used as in the 1st example with the exception of the following deviations: Starting powder for the production of the anode disk and the stump from TZM (and not from MHC) is provided. The frictional pressure used is only 25 bar and the upsetting pressure is increased to only 60 bar after the anode disk has been driven.
• Example 3 A manufacturing method of an X-ray rotating anode according to the invention, in which the anode disk and the bearing bush are made of TZM and are connected to one another via diffusion bonding, is described below.
• the anode disk and a tubular stump are produced from TZM.
• Both the (to be connected) end face of the tubular stump and the (to be connected) end face of the connecting piece are mechanically machined and then ground and / or polished in order to provide a smooth planar surface.
• the diffusion bonding of the two components is then carried out with their end faces resting against one another at a temperature of 1,700 ° C., a pressure of 10 MPa and a duration of at least 5 minutes (preferably in the range of 6-15 minutes).
• liquid metal bearing running surface of the liquid metal bearing outer shell does not necessarily have to have a rectilinear course in the form of a cylinder jacket surface, but rather, as explained at the beginning, it can also have a stepped course, a circumferential rib, etc.
• Liquid metal bearing inner shell has a correspondingly adapted course.

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• 2020
  • 2020-02-20 AT ATGM50033/2020U patent/AT17209U1/de unknown
• 2021
  • 2021-01-28 US US17/801,334 patent/US12100572B2/en active Active
  • 2021-01-28 CN CN202180015187.0A patent/CN115136275A/zh active Pending
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