KR20190113429A - Target of X-ray tube, X-ray tube with the same, and method for fabricating the X-ray target - Google Patents

Abstract

Disclosed are a target of an X-ray tube in which electrons collide to emit X-rays, an X-ray tube having the target, and a manufacturing method of the X-ray tube. The disclosed target of the X-ray tube comprises: a base layer made of metal including molybdenum and having a plurality of bond reinforcing grooves formed on one surface thereof; and an electron collision layer formed by spraying and hardening metal including tungsten on one surface of the base layer. Each of the bond reinforcing grooves has an inclined side so that a width thereof becomes wider as the width deepens on one surface of the base layer and extends from one surface of the base layer to be longer in width and depth. The electron collision layer has a surface penetration unit in which a plurality of bonded reinforcing grooves are filled with the sprayed metal and hardened, and a surface lamination unit laminated on one surface of the base layer and formed integrally with the surface penetration unit.

Description

Target of X-ray tube, X-ray tube with the same, and method for fabricating the X-ray target}

The present invention relates to an X-ray tube, and more particularly, to an X-ray tube target for emitting X-rays by electron collision, an X-ray tube having the same, and a method of manufacturing the X-ray tube target.

When electrons strike the target at high speed, X-rays are emitted. An X-ray tube is used to intentionally emit X-rays using this principle. An X-ray tube is included therein, and a device used as a medical imaging apparatus for observing the inside of a human body using X-rays emitted, for example, is called an X-ray tube apparatus.

In the X-ray tube, electrons are accelerated to the target by the potential difference between an anode, that is, a target and a cathode, and X-rays are emitted. The X-ray tube target has a base layer made of molybdenum (Mo) or molybdenum alloy having high heat resistance, and an electron collision layer made of tungsten (W) or tungsten alloy, laminated on the base layer. A heat dissipation layer made of graphite may be further attached below the base layer to promote heat dissipation.

The base layer and the electron collision layer of the X-ray tube target were integrally formed by a powder metallurgy method. In addition, the X-ray tube target formed by the powder metallurgy is subjected to a forging process to densify the structure and enhance the rigidity. Therefore, the time required for manufacturing the X-ray tube target is long, the productivity is lowered, and the manufacturing cost increases because both the apparatus for powder metallurgy and the forging processing apparatus must be provided. In addition, if the electron collision layer is partially worn or etched by repeating the X-ray emission operation, the X-ray tube target is discarded, and thus resources are wasted and maintenance costs of the X-ray tube are increased.

Republic of Korea Patent Publication No. 10-1434821

The present invention provides an X-ray tube target having improved quality and manufacturing productivity and a reduced manufacturing cost, a method of manufacturing the X-ray tube target, and an X-ray tube having the X-ray tube target.

According to the present invention, electrons collide to emit X-rays, and are formed of a metal including molybdenum (Mo), and a base layer having a plurality of bond reinforcing grooves formed on one surface thereof, and the base layer. A tungsten (W) -containing metal is sprayed and hardened on one surface of the electron collision layer, and the plurality of bond reinforcing grooves are each wider as they are deeper on one surface of the base layer. The fork side is inclined and extends from one surface of the base layer to be longer in length than the width and depth of the bond reinforcing groove, wherein the electron collision layer is filled with the sprayed metal in the plurality of bond reinforcing grooves. An X-ray tube target having a cured surface penetrating portion and a surface stacking portion laminated on one surface of the base layer and integrally formed with the surface penetrating portion is provided.

The metal component constituting the electron collision layer may include 3 to 10 wt% of radium (Ra).

The depth of the coupling reinforcement groove is 0.8 to 3.0mm, the angle formed by the side and the bottom surface of the coupling reinforcement groove may be 30 to 60 °.

The width of the bottom surface of the coupling reinforcement groove may be 7 to 15mm.

The plurality of bonding reinforcement grooves may be arranged concentrically on one surface of the base layer.

In addition, the present invention is a vacuum tube (vacuum tube) in which the internal space is a vacuum state, a cathode for projecting electrons (electron) into the vacuum tube, and the electrons disposed inside the vacuum tube, the electrons projected from the cathode Provided is an X-ray tube having an X-ray tube target of the present invention as described above, wherein electrons collide with each other to emit X-rays.

In addition, the present invention is a method of manufacturing the X-ray tube target of the present invention described above, by machining a base material made of a metal containing molybdenum (Mo) to form a base layer free of the plurality of bonding reinforcement grooves A base layer forming step, a bond reinforcing groove processing step of forming a plurality of bond reinforcing grooves by machining one surface of the base layer, and a powder of metal including tungsten (W) on one surface of the base layer. Provided is a method for producing an X-ray tube target having a thermal spraying step of thermal spraying and cooling to form an electron collision layer having the surface penetrating portion and the surface stacking portion.

The spraying step may include a plasma spraying step of spraying the metal powder on a plasma and spraying the metal powder onto one surface of the base layer while melting the metal powder.

The bonding reinforcing groove machining step may include cutting and forming the plurality of bonding reinforcing grooves on one surface of the base layer by using an end mill as a cutting tool.

The base layer forming step may include a step of forging the base material.

Components of the metal powder injected in the thermal spraying step may include 3 to 10 wt% of radium (Ra).

The X-ray tube target of the present invention includes a processed base layer and a spray-coated electron collision layer. In this case, since the base layer can be purchased and used in mass production, manufacturing cost is reduced and manufacturing time is reduced and productivity is improved compared to the conventional X-ray tube target formed by forging after powder metallurgy.

In addition, the X-ray tube target of the present invention is linked as if the electron collision layer and the base layer are fastened to the hook due to the surface penetration layer formed to fill the bonding reinforcement groove formed in the base layer, so that the electron collision layer is connected to the base layer. Not separated for improved quality reliability and durability.

Meanwhile, when the electron collision layer is partially worn or etched, the X-ray tube target of the present invention can easily regenerate the electron collision layer by spraying a metal containing tungsten (W) on the surface of the base layer again. Therefore, since the X-ray tube target is not discarded, waste of resources is suppressed and maintenance cost of the X-ray tube is reduced.

1 is a cross-sectional view of an X-ray tube according to an embodiment of the present invention.
FIG. 2 is an enlarged cross-sectional view of part A of FIG. 2.
3 is a plan view illustrating a base layer of an X-ray tube target according to an exemplary embodiment of the present invention.
4 is a cross-sectional view illustrating a spraying step during a manufacturing process of an X-ray tube target according to an exemplary embodiment of the present invention.

Hereinafter, an X-ray tube target according to an embodiment of the present invention, an X-ray tube having the same, and a method of manufacturing the X-ray tube target will be described in detail with reference to the accompanying drawings. Terminology used herein is a term used to properly express a preferred embodiment of the present invention, which may vary depending on the intention of a user or an operator or customs in the field to which the present invention belongs. Therefore, the definitions of the terms should be made based on the contents throughout the specification.

1 is a cross-sectional view of an X-ray tube according to an embodiment of the present invention, FIG. 2 is an enlarged cross-sectional view of part A of FIG. 2, and FIG. 3 is a view showing a base layer of an X-ray tube target according to an embodiment of the present invention. Top view. 1 to 3 together, the X-ray tube 10 according to an embodiment of the present invention, for example, X-ray tube apparatus (not shown) included in a medical imaging device, such as computed tomography (CT) imaging device It is inserted into the inside and emits X-rays and emits X-rays. The vacuum tube 11, the cathode 16, the anode 30, and the rotor 28, and a stator (not shown).

The vacuum tube 11 is also called a bellcan because its appearance is similar to a bell. The vacuum tube 11 has a large diameter portion 13 having a relatively large diameter and a small diameter portion 14 which is connected to the large diameter portion 13 and is disposed below the large diameter portion 13 and smaller in diameter than the large diameter portion 13. It is provided. The vacuum tube 11 is sealed, and the inner space of the vacuum tube 11 is kept in a high vacuum state.

The cathode 16 is fixed on the upper side of the vacuum tube 11, and forms a potential difference of approximately 150V (volt) between the anode 30. Electrons generated at the cathode 16 are accelerated by the potential difference and are projected onto the anode 30. Since electrons are projected and collided on the anode 30, the anode 30 is also called an X-ray tube target.

The X-ray tube target 30 is a disk-shaped member, a base layer 31 made of a metal containing molybdenum (Mo), that is, a molybdenum alloy containing pure molybdenum or molybdenum as a main material, Electron impinging layer in which a metal including tungsten (W), that is, pure tungsten (W) or a tungsten alloy containing tungsten as a main material, is laminated on one surface 33 of the base layer 31, specifically, the upper peripheral portion ( 40). The electrons projected from the cathode 16 collide with the electron collision layer 40 to emit X-rays. Although not shown in FIG. 1, the X-ray tube target 30 may further include a heat dissipation layer made of graphite or C-C composite (carbon-carbon composite) under the base layer 31 to promote heat dissipation.

The target connecting shaft 23 fitted into the through hole 32 penetrating the center of the X-ray tube target 30 in the vertical direction and fixed to the X-ray tube target 30 by the fixing cap 27 is X The ship tube target 30 is rotatably supported about the virtual rotation axis RC extended in the up-down direction. The cylindrical rotor 28 disposed inside the small diameter portion 14 of the vacuum tube 11 is fixedly coupled to the target connecting shaft 23. An upper end of the inner shaft 25 extending along the rotational axis RC inside the rotor 28 is fixedly coupled to the target connecting shaft 23. The shaft support 17 is fixedly coupled to the lower end of the vacuum tube 11 so that the lower end of the vacuum tube 11 is sealed, and the upper bearing 21 and the lower bearing 22 are the inner shaft 25. And is interposed between the shaft support 17. In such a configuration, the inner shaft 25, the rotor 28, the target connecting shaft 23, and the X-ray tube target 30 fixedly coupled to each other have an axis of rotation on the shaft support 17 inside the vacuum tube 11. It is supported so that it may rotate at high speed about RC.

The stator (not shown) has a coil (not shown) wound around the rotor 28 outside the small diameter portion 14 of the vacuum tube 11. When a current is applied to the coil, an electromagnetic force is generated, and the rotor 28 and the inner shaft 25 fixedly coupled thereto, the target connecting shaft 23, and the X-ray tube target 30 are rotated by the electromagnetic force. It will rotate based on RC).

The electron collision layer 40 of the X-ray tube target 30 is formed by spraying and hardening a metal containing tungsten (W) on the upper outer peripheral portion 33 of the base layer 31. In order to increase the bonding force between the electron collision layer 40 and the base layer 31 in the spray coating (coating), the metal constituting the electron collision layer 40 may include 3 to 10wt% of radium (Ra). .

In order to enhance the bonding force between the electron collision layer 40 and the base layer 31, a plurality of bonding reinforcement grooves 35 are formed in the upper outer peripheral portion 33 of the base layer 31, and the electron collision layer 40 is formed. The metal including the tungsten (W) is sprayed and filled into the plurality of bond reinforcing grooves 35 and laminated on the hardened surface penetrating portion 41 and the upper outer peripheral portion 33 of the base layer 31. And a surface stacking portion 43 formed integrally with the surface penetrating portion 41. In FIG. 2, the dashed-dotted line is an imaginary line separating the surface penetrating portion 41 and the surface stacking portion 43. In the actual X-ray tube target 30, the surface penetrating portion 41 and the surface stacking portion 43 are shown in FIG. 2. It may not be clearly distinguished in a straight line as shown in 2.

Each side of the plurality of coupling reinforcing grooves 35 formed in the base layer 31 is inclined so that the width of the coupling reinforcing grooves 35 increases as the upper side outer peripheral portion 33 deepens. In addition, each engaging reinforcement groove 35 extends from the upper peripheral portion 33 so that its length is longer than its width and depth DP. The depth DP of the engagement reinforcement groove 35 is 0.8 to 3.0 mm, and the angle AN at which the side 37 and the bottom surface 36 of the engagement reinforcement groove 35 intersect is 30 to 60 °. In addition, the width WD of the bottom surface 36 of the coupling reinforcement groove 35 is 7 to 15 mm.

In FIG. 2, a cross-section of both bottom edges 36e at which the side 37 and the bottom 36 of the coupling reinforcing groove 35 intersect, and the surface 33 of the base layer 31, ie, the top side Although the cross section of the edge where the side surface 37 crosses is illustrated as a sharp acute angle like a wedge, in actual X-ray tube target 30, the cross section of the edges may have a slightly blunt curved shape.

As shown in FIG. 3, the plurality of coupling reinforcement grooves 35 are arranged concentrically about the rotation center of the base layer 31, that is, the rotation axis RC, on the upper circumferential outer circumferential surface 33. However, the planar shape of the plurality of coupling reinforcement grooves in the X-ray tube target of the present invention is not limited to the concentric shape as shown in FIG. 3, for example, in a radial direction about the rotation axis RC. ) Or a helical curve around the rotation axis RC.

Compared to the X-ray tube target having a smooth interface between the base layer and the electron collision layer, the X-ray tube target 30 shown in FIGS. 1 and 2 has contact bonding at the interface between the electron collision layer 40 and the base layer 31. Since the surface area is enlarged, the bonding force between the base layer 31 and the electron collision layer 40 is enhanced. In other words, the plurality of bonding reinforcement grooves 35 are filled and cured so that the surface penetrating portion 41 of the electron collision layer 40 interferes with each other such that they do not exit from the bonding reinforcement grooves 35 as if they are hooks. The bonding force between the base layer 31 and the electron collision layer 40 is further enhanced.

Hereinafter, a method of manufacturing the X-ray tube target 30 will be described in more detail. 4 is a cross-sectional view illustrating a spraying step during a manufacturing process of an X-ray tube target according to an exemplary embodiment of the present invention. 2 and 3 together, the method for manufacturing the X-ray tube target 30 includes a base layer forming step, a bonding strengthening groove processing step, and a thermal spraying step. The base layer forming step may be performed by machining a base metal made of molybdenum (Mo), that is, a pure molybdenum or molybdenum alloy, to form a base layer 31 without a plurality of bond reinforcing grooves 35. It's a step. The machining may include a forging process that strikes the base material to deform into a disk shape similar to that of the base layer 31 and at the same time strengthens the rigidity. The forged base material can purchase a mass-produced ready-made product, and the manufacturer of the X-ray tube target 30 performs the finishing process such as cutting and grinding the forged base material, for example, the base layer 31. It can be prepared by.

The joining groove machining step is a step of forming a plurality of joining reinforcement grooves 35 by machining one surface 33 of the base layer 31, that is, the outer peripheral portion of the upper side. The plurality of joining reinforcement grooves 35 cut the plurality of joining reinforcement grooves 35 in the outer peripheral portion 33 of the upper side of the base layer 31 using an end mill (not shown) as a cutting tool. It can be formed by processing. Since the specific shape of the coupling reinforcement groove 35 has been described above, a redundant description thereof will be omitted. Meanwhile, the plurality of coupling reinforcement grooves 35 may not be formed only by cutting using an end mill. For example, a photo may include a photoresist coating step, a masking step, a developing step, and an etching step. It may also be formed through a lithography process.

Referring to FIGS. 2 to 4, the spraying step includes spraying a metal including tungsten (W), that is, a powder of pure tungsten (W) or a tungsten alloy on the outer peripheral portion 33 of the upper side of the base layer 31. V) and cooling to form an electron collision layer having the surface penetrating portion 41 and the surface stacking portion 43. The spraying step may include a plasma spraying step in which the powder of the metal including the tungsten is loaded into a plasma, and sprayed onto the upper outer peripheral portion 33 of the base layer 31 while melting the powder of the metal. . The plasma spraying step may be performed using a plasma spray torch 60.

 The plasma spray torch 60 has a cathode 61 protruding in the form of a pin in a central portion thereof, and a nozzle opening 64 formed in front of the cathode electrode 61 while surrounding the cathode electrode 61. An anode electrode 62 is provided. An inert gas such as argon, hydrogen, nitrogen, and helium is supplied through the inert gas supply portion 67 around the cathode electrode 61 to plasmalize between the cathode electrode 61 and the anode electrode 62, and the nozzle opening 64. A plasma jet is sprayed to the front of the torch 60 through (). In order to prevent overheating of the torch 60, the coolant is supplied to the peripheral portion of the anode electrode 62 through the coolant supply unit 68.

When a powder of metal including tungsten is introduced through the powder input part 66 on the front side of the torch 60, the molten metal is melted by the plasma jet, and the molten metal is loaded on the plasma jet to the front of the torch 60. The electron collision layer 40 is formed by coating and cooling the outer circumference of the upper surface 32 of the base layer 31 disposed therein. In a preferred embodiment, the metal containing tungsten (W) is a tungsten alloy, the component of which may include 3 to 10wt% of radium (Ra). The radium Ra increases the adhesion between the sprayed tungsten alloy and the upper peripheral portion 33 of the base layer 31, thereby increasing the bonding force between the base layer 31 and the electron collision layer 40. The metal that has been thermally sprayed and filled in the bond reinforcing groove 35 becomes the surface penetrating portion 41, and the metal that is laminated and cured onto the surface laminating portion 43 becomes the surface penetrating portion 41. And surface laminated portion 43 are united together and cured.

The X-ray tube target 30 described above includes a base layer 31 and an electron collision layer 40 spray-coated on one surface thereof. In this case, since the base layer 31 can be purchased and used in mass production, manufacturing cost is reduced and manufacturing time is shortened compared to the conventional X-ray tube target formed by forging after powder metallurgy, thereby improving productivity. In addition, since no powder metallurgy equipment or forging apparatus is required, the initial investment cost for manufacturing the X-ray tube target can be reduced.

In addition, the X-ray tube target 30 has an electron collision layer 40 and the base layer 31 hooked due to the surface penetration layer 41 formed to fill the coupling reinforcement groove 35 formed in the base layer 31. As it is coupled to the hook, the electron collision layer 40 is not separated from the base layer 31, thereby improving quality reliability and durability.

On the other hand, the X-ray tube target 30 of the present invention is easy by spraying a metal containing tungsten (W) on the surface of the base layer 31 when the electron collision layer 40 is partially worn or etched. The electron collision layer 40 can be reproduced easily. Therefore, since the X-ray tube target 30 is not discarded, waste of resources is suppressed and maintenance cost of the X-ray tube is reduced.

Although the present invention has been described with reference to the embodiments shown in the drawings, this is merely exemplary, and it will be understood by those skilled in the art that various modifications and equivalent other embodiments are possible. Therefore, the true scope of protection of the present invention should be defined only by the appended claims.

10: X-ray tube 11: vacuum tube
16: cathode 28: rotor
30: X-ray tube target 31: base layer
35: bonding strengthening groove 40: electron collision layer

Claims (11)

Electrons collide to emit X-rays,
A base layer made of a metal including molybdenum (Mo) and having a plurality of bond reinforcing grooves formed on one surface thereof; And an electron collision layer formed by spraying and hardening a metal including tungsten (W) on one surface of the base layer.
Each of the plurality of bonding reinforcement grooves is inclined to the side thereof to become wider as it is deeper on one surface of the base layer, and extends from one surface of the base layer to be longer than the width and depth of the coupling reinforcement groove. ,
The electron collision layer includes a surface penetrating portion filled with the sprayed metal in the plurality of bond reinforcing grooves, and a surface stacking portion laminated on one surface of the base layer and integrally formed with the surface penetrating portion. X-ray tube target, characterized in that. The method of claim 1,
The metal component constituting the electron collision layer X-ray tube target, characterized in that it contains 3 to 10wt% of radium (Ra). The method of claim 1,
The depth of the coupling reinforcement groove is 0.8 to 3.0mm,
X-ray tube target, characterized in that the angle between the side and the bottom surface of the coupling reinforcement groove is 30 to 60 °. The method of claim 3, wherein
X-ray tube target, characterized in that the width of the bottom surface of the coupling reinforced groove is 7 to 15mm. The method of claim 1,
The plurality of bonding reinforcement grooves are arranged in a concentric manner on one surface of the base layer X-ray tube target. A vacuum tube in which the internal space is in a vacuum state;
A cathode for projecting electrons into the vacuum tube; And,
And an X-ray tube target disposed inside the vacuum tube and emitting X-rays due to collision of electrons projected from the cathode.
The X-ray tube target is an X-ray tube, characterized in that the X-ray tube target of any one of claims 1 to 5. A method of manufacturing the X-ray tube target of any one of claims 1 to 5,
A base layer forming step of forming a base layer free of the plurality of bond reinforcing grooves by machining a base metal made of molybdenum (Mo);
A bond reinforcing groove machining step of machining one surface of the base layer to form the plurality of bond reinforcing grooves; And,
And a thermal spraying step of thermally spraying and cooling the metal powder including tungsten (W) on one surface of the base layer to form an electron collision layer having the surface penetrating portion and the surface stacking portion. Method for producing an X-ray tube target. The method of claim 7, wherein
The spraying step, the method of manufacturing an X-ray tube target, characterized in that the plasma spraying step of spraying the metal powder on the plasma (plasma), while melting the metal powder on one surface of the base layer. The method of claim 7, wherein
The bonding reinforcing groove processing step, the end mill (end mill) using a cutting tool comprising the step of forming the plurality of bonding reinforcing grooves on one surface of the base layer, characterized in that it comprises a step . The method of claim 7, wherein
The base layer forming step includes the step of forging the base material manufacturing method of the X-ray tube target. The method of claim 7, wherein
The method of manufacturing an X-ray tube target, characterized in that 3 to 10wt% of radium (Ra) is included in the component of the metal powder to be injected in the spraying step.

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