JP6008634B2 - X-ray tube apparatus and X-ray CT apparatus - Google Patents

Description

  The present invention relates to an X-ray tube apparatus and an X-ray CT (Computed Tomography) apparatus, and more particularly to a ball bearing used in a high temperature environment or a vacuum atmosphere.

  An X-ray CT device is an X-ray tube device that irradiates a subject with X-rays, and an X-ray detector that detects X-ray dose transmitted through the subject as projection data by rotating the subject around the subject. The tomographic image of the subject is reconstructed using the obtained projection data from a plurality of angles, and the reconstructed tomographic image is displayed. The image displayed by the X-ray CT apparatus describes the shape of an organ in the subject and is used for diagnostic imaging.

  In recent developments of X-ray CT apparatuses, the imaging time has been shortened by rotating a scanner equipped with an X-ray tube apparatus and an X-ray detector at a higher speed. To maintain the quality of tomographic images even when the scanner rotates at high speed, it is necessary to increase the X-ray dose per unit time generated from the X-ray tube device. To increase the X-ray dose, the tube current must be increased, and the amount of heat generated in the X-ray tube increases. The amount of heat generated in the X-ray tube has several adverse effects on the X-ray tube. For example, it causes adverse effects such as melting of the X-ray target due to overheating of the anode, thermal expansion of the rotating shaft of the anode, especially rotation failure due to thermal expansion of the ball bearing.

  As a rolling bearing suitable for use in a vacuum or high-temperature environment, Patent Document 1 discloses that the surface of a rolling element made of steel material has three layers of Sn and Ag, Bi and Pb, or Ni, Cu, Sn, and Pb. A rolling bearing coated with a four-layer lubricating film is disclosed.

Japanese Patent Laid-Open No. 7-190067

  However, the rolling bearing as disclosed in Patent Document 1 is insufficient for use in an X-ray tube apparatus in which the amount of heat generated in the X-ray tube is larger, and further contrivance is required. That is, in the process of manufacturing the X-ray tube device, the rotational axis of the anode reaches 400 ° C. or more, whereas in the lubricating film composed of three layers of Sn and Ag, Bi and Pb, Ag, Bi and Sn Since the alloy is easily alloyed and the melting point of the alloy is lower than 400 ° C., there is a concern that the lubricating film composed of three layers may be peeled off and the lubrication function may be deteriorated due to the surface exposure of the rolling elements. In addition, in a lubricating film consisting of four layers of Ni, Cu, Sn, and Pb, there is a concern that the lubrication function may be deteriorated due to exposure of Cu, which is too hard as a lubricating film, to the lubricating surface due to melting of Sn and Pb. .

  Accordingly, an object of the present invention is to provide an X-ray tube device having a structure capable of suppressing a decrease in the lubrication function of the ball bearing even when the temperature of the rotating shaft of the anode reaches 400 ° C. or higher, and the X-ray tube device. It is to provide an on-board X-ray CT system.

  In order to achieve the above object, the present invention provides an X-ray tube apparatus comprising an anode that emits X-rays when irradiated with an electron beam, and an anode rotation driving unit that rotates the anode, wherein the anode rotation The drive unit has a rolling element, and at least one of the raceway surface that contacts the rolling element or the surface of the rolling element, a Ni film as a lowermost layer film, an Ag film formed above the Ni film, A multilayer lubricating film having a Pb film formed above the Ag film is provided.

  In addition, the X-ray tube device, the X-ray detector that is disposed opposite to the X-ray tube device and detects X-rays transmitted through the subject, the X-ray tube device and the X-ray detector are mounted, and the target is mounted. A rotating disk that rotates around the specimen, an image reconstruction device that reconstructs a tomographic image of the subject based on transmitted X-ray doses from a plurality of angles detected by the X-ray detector, and the image reconstruction device. An X-ray CT apparatus comprising: an image display device that displays a reconstructed tomographic image.

  According to the present invention, even if the temperature of the rotating shaft of the anode reaches 400 ° C. or higher, the present invention provides an X-ray tube device having a structure capable of suppressing a decrease in the lubrication function of the ball bearing, and mounting the X-ray tube device An X-ray CT apparatus can be provided.

The block diagram which shows the whole structure of the X-ray CT apparatus of this invention The figure which shows the whole structure of the X-ray tube apparatus of this invention The figure which shows the anode periphery of the X-ray tube apparatus of this invention The figure which shows the structure of the ball bearing of this invention The figure which shows 1st embodiment of the surface structure of the rolling element of the ball bearing of this invention The figure which shows 2nd embodiment of the surface structure of the rolling element of the ball bearing of this invention. The figure which shows 3rd embodiment of the surface structure of the rolling element of the ball bearing of this invention.

  Hereinafter, preferred embodiments of an X-ray CT apparatus according to the present invention will be described with reference to the accompanying drawings. In the following description and the accompanying drawings, the same reference numerals are given to the constituent elements having the same functional configuration, and redundant description will be omitted.

  The overall configuration of the X-ray CT apparatus 1 to which the present invention is applied will be described with reference to FIG. The X-ray CT apparatus 1 includes a scan gantry unit 100 and a console 120.

  The scan gantry unit 100 includes an X-ray tube device 101, a rotating disk 102, a collimator 103, an X-ray detector 106, a data collection device 107, a bed 105, a gantry control device 108, and a bed control device 109. An X-ray control device 110. The X-ray tube device 101 is a device that irradiates a subject placed on a bed 105 with X-rays. The collimator 103 is a device that limits the radiation range of X-rays emitted from the X-ray tube device 101. The rotating disk 102 includes an opening 104 into which the subject placed on the bed 105 enters, and is equipped with an X-ray tube device 101 and an X-ray detector 106, and rotates around the subject. The X-ray detector 106 is a device that measures the spatial distribution of transmitted X-rays by detecting X-rays that are disposed opposite to the X-ray tube device 101 and transmitted through the subject. The rotating disk 102 is arranged in the rotating direction, or the rotating disk 102 is arranged two-dimensionally in the rotating direction and the rotating shaft direction. The data collection device 107 is a device that collects the X-ray dose detected by the X-ray detector 106 as digital data. The gantry control device 108 is a device that controls the rotation of the rotary disk 102. The bed control device 109 is a device that controls the vertical and horizontal movements of the bed 105. The X-ray control device 110 is a device that controls electric power input to the X-ray tube device 101.

  The console 120 includes an input device 121, an image arithmetic device 122, a display device 125, a storage device 123, and a system control device 124. The input device 121 is a device for inputting a subject's name, examination date and time, imaging conditions, and the like, specifically a keyboard or a pointing device. The image computation device 122 is a device that performs CT processing on the measurement data sent from the data collection device 107 and performs CT image reconstruction. The display device 125 is a device that displays the CT image created by the image calculation device 122, and is specifically a CRT (Cathode-Ray Tube), a liquid crystal display, or the like. The storage device 123 is a device that stores data collected by the data collection device 107 and image data of a CT image created by the image calculation device 122, and is specifically an HDD (Hard Disk Drive) or the like. The system control device 124 is a device that controls these devices, the gantry control device 108, the bed control device 109, and the X-ray control device 110.

  The X-ray tube device 101 is controlled by the X-ray controller 110 controlling the power input to the X-ray tube device 101 based on the imaging conditions input from the input device 121, in particular, the X-ray tube voltage and the X-ray tube current. Irradiates the subject with X-rays according to imaging conditions. The X-ray detector 106 detects X-rays irradiated from the X-ray tube apparatus 101 and transmitted through the subject with a large number of X-ray detection elements, and measures the distribution of transmitted X-rays. The rotating disk 102 is controlled by the gantry control device 108, and rotates based on the photographing conditions input from the input device 121, particularly the rotation speed. The couch 105 is controlled by the couch controller 109 and operates based on the photographing conditions input from the input device 121, particularly the helical pitch.

  By repeating the X-ray irradiation from the X-ray tube device 101 and the measurement of the transmitted X-ray distribution by the X-ray detector 106 along with the rotation of the rotating disk 102, projection data from various angles is acquired. The acquired projection data from various angles is transmitted to the image calculation device 122. The image calculation device 122 reconstructs the CT image by performing back projection processing on the transmitted projection data from various angles. The CT image obtained by the reconstruction is displayed on the display device 125.

  Depending on the size of the opening 104 of the rotating disk 102 and the thickness of the scan gantry unit 100, the subject may feel a sense of pressure. Therefore, it is desirable that the opening 104 is large and the scan gantry unit 100 is thin. Since the size of the opening 104 and the thickness of the scan gantry unit 100 depend on the size of the load on the rotating disk 102, it is preferable that the X-ray tube device 101, which is one of the loads, is smaller. .

  The configuration of the X-ray tube apparatus 101 will be described with reference to FIG. The X-ray tube apparatus 101 includes an X-ray tube 210 that generates X-rays and a container 220 that stores the X-ray tube 210.

  The X-ray tube 210 includes a cathode 211 that generates an electron beam, an anode 212 to which a positive potential is applied to the cathode 211, and an envelope 213 that holds the cathode 211 and the anode 212 in a vacuum atmosphere.

  The cathode 211 includes a filament or a cold cathode and a focusing electrode. The filament is formed by winding a high melting point material such as tungsten in a coil shape, and is heated when a current is passed to emit thermoelectrons. A cold cathode is formed by sharpening a metal material such as nickel or molybdenum, and emits electrons by field emission when an electric field is concentrated on the cathode surface. The focusing electrode forms a focusing electric field for focusing the emitted electrons toward the X-ray focal point on the anode 212. The filament or cold cathode and the focusing electrode are at the same potential.

  The anode 212 includes a target and an anode base material. The target is made of a material having a high melting point and a large atomic number, such as tungsten. X-rays 217 are emitted from the X-ray focal point when electrons emitted from the cathode 211 collide with the X-ray focal point on the target. The anode base material holds the target and is made of a material having high thermal conductivity such as copper. The target and the anode base material are at the same potential.

  The envelope 213 maintains the cathode 211 and the anode 212 in a vacuum atmosphere in order to electrically insulate the cathode 211 and the anode 212 from each other. The envelope 213 is provided with a radiation window 218 for emitting X-rays 217 to the outside of the X-ray tube 210. The radiation window 218 is made of a material having a small atomic number such as beryllium having a high X-ray transmittance. The radiation window 218 is also provided in the container 220 described later. The potential of the envelope 213 is a ground potential.

  The electrons emitted from the cathode 211 are accelerated by a voltage applied between the cathode and the anode and become an electron beam 216. When the electron beam 216 is focused by the focusing electric field and collides with the X-ray focal point on the target, X-rays 217 are generated from the X-ray focal point. The energy of the generated X-ray is determined by the voltage applied between the cathode and the anode, so-called tube voltage. The dose of X-rays generated is determined by the amount of electrons emitted from the cathode, the so-called tube current and the tube voltage.

  Of the energy of the electron beam 216, the ratio of being converted to X-rays is only about 1%, and most of the remaining energy is heat. In the X-ray tube apparatus 101 mounted on the medical X-ray CT apparatus 1, the tube voltage is hundreds of kV and the tube current is several hundred mA, so the anode 212 is heated with a heat quantity of several tens kW. In order to prevent the anode 212 from being overheated and melted by such heating, the anode 212 is connected to the rotating body support mechanism 215, and the one-dot chain line 219 in FIG. Rotates as an axis. The rotating body support mechanism 215 drives the magnetic field generated by the excitation coil 214 as a rotational driving force. By rotating the anode 212, the X-ray focal point where the electron beam 216 collides always moves, so that the temperature of the X-ray focal point can be kept lower than the melting point of the target, and the anode 212 can be overheated and melted. Can be prevented.

  The X-ray tube 210 and the excitation coil 214 are accommodated in the container 220. The container 220 is filled with cooling water as a cooling medium or an insulating oil as a cooling medium while electrically insulating the X-ray tube 210. Cooling water or insulating oil filled in the container 220 is guided to the cooler through a pipe connected to the container 220 of the X-ray tube device 101, and after the heat is dissipated in the cooler, the heat is dissipated in the container 220 through the pipe. Returned.

  The anode 212 has an average temperature of about 1000 ° C. due to heat generated at the X-ray focal point. Most of the generated heat is radiated from the surface of the anode 212 to the envelope 213 by radiation, and the remaining heat flows to the envelope 213 through the rotating body support mechanism 215 by heat conduction. Since the heat flowing to the rotating body support mechanism 215 causes various harmful effects, it is necessary to take measures against heat in the rotating body support mechanism 215.

  The rotating body support mechanism 215 connected to the anode 212 will be described in detail with reference to FIG. FIG. 3 is a view showing the structure around the anode 212. The rotating body support mechanism 215 has an anode 212 connected to the back side of the surface facing the cathode 211, a fixed portion 300, an anode-side ball bearing 8, an end-side ball bearing 9, a rotating shaft portion 7, and a rotating cylinder. Part 301.

  The fixed part 300 has a cylindrical shape, and one end is supported by the envelope 213. The anode side ball bearing 8 and the end side ball bearing 9 are held on the inner surface of the fixed portion 300.

  The anode-side ball bearing 8 and the end-side ball bearing 9 are so-called rolling bearings that support the rotary shaft portion 7 so as to be rotatable with respect to the fixed portion 300. Details of the anode side ball bearing 8 and the end side ball bearing 9 will be described later.

  The rotating shaft portion 7 has a cylindrical shape and is disposed inside the fixed portion 300. A rotating cylindrical portion 301 is connected to the rotating shaft portion 7, and an anode 212 is connected to the rotating cylindrical portion 301. A metal having a low thermal conductivity, such as stainless steel, may be interposed between the rotating cylindrical portion 301 and the rotating shaft portion 7 in order to suppress the amount of heat transfer.

  The rotating cylindrical portion 301 has a cylindrical shape, and the fixed portion 300 and the rotating shaft portion 7 are disposed inside the rotating cylindrical portion 301. The rotating cylindrical portion 301 rotates around the alternate long and short dash line 219 by receiving the magnetic field generated by the exciting coil 214. Along with the rotation of the rotating cylindrical portion 301, the anode 212 and the rotating shaft portion 7 connected to the rotating cylindrical portion 301 also rotate around the alternate long and short dash line 219. In the following description, the rotation axis of the anode 212 is referred to as a rotation axis 219 using the reference numeral 219.

  The anode side ball bearing 8 and the end side ball bearing 9 will be described in detail with reference to FIG. The anode side ball bearing 8 is disposed on the side close to the anode 212 in the rotation axis direction, and includes an anode side inner ring raceway groove 8c, an anode side outer ring raceway groove 8a, and an anode side ball 82. The end side ball bearing 9 is arranged on the side far from the anode 212 in the rotation axis direction, and, like the anode side ball bearing 8, the end side inner ring raceway groove 9c, the end side outer ring raceway groove 9a, and the end side ball And 92. The anode side ball bearing 8 and the end side ball bearing 9 may be integral type ball bearings.

  The anode side inner ring raceway groove 8 c and the end portion side inner ring raceway groove 9 c are grooves formed on the outer periphery of the rotating shaft portion 7. In a cross section parallel to the rotation shaft 219 and including the rotation shaft 219, the anode side inner ring raceway groove 8c and the end portion side inner ring raceway groove 9c have an arc shape.

  The anode-side outer ring raceway groove 8a and the end-side outer ring raceway groove 9a are grooves respectively formed on the inner peripheral surfaces of the anode-side outer ring 81 and the end-side outer ring 91 having an annular shape. In the cross section parallel to the rotation shaft 219 and including the rotation shaft 219, the anode side outer ring raceway groove 8a and the end portion side outer ring raceway groove 9a have an arc shape.

  The anode-side outer ring 81 and the end-side outer ring 91 are concentric with the rotating shaft portion 7, and the anode-side inner ring raceway groove 8c and the anode-side outer ring raceway groove 8a face each other, and the end-side inner ring raceway groove 9c. And the end portion side outer ring raceway groove 9a are arranged on the inner peripheral surface of the fixed portion 300 so as to face each other. The anode-side outer ring 81 and the end-side outer ring 91 are arranged at predetermined intervals in the direction of the rotation shaft 219 by a cylindrical spacer 11 and a C spacer 12 having a C-shaped cross section.

  The anode side ball 82 and the end side ball 92 have a spherical shape. The anode-side ball 82 rotates between the anode-side inner ring raceway groove 8c and the anode-side outer ring raceway groove 8a, and the end-side ball 92 rotates between the end-side inner ring raceway groove 9c and the end-side outer ring raceway groove 9a. A plurality of each are arranged in the circumferential direction around the shaft 219. The radius of the anode side ball 82 is set smaller than the curvature radius of the anode side inner ring raceway groove 8c and the anode side outer ring raceway groove 8a, and the radius of the end side ball 92 is the end side inner ring raceway groove 9c and the end side outer ring raceway. It is set smaller than the radius of curvature of the groove 9a.

  The anode-side ball 82 is between the anode-side inner ring raceway groove 8c and the anode-side outer ring raceway groove 8a, and the end-side ball 92 is between the end-side inner ring raceway groove 9c and the end-side outer ring raceway groove 9a. By rolling, the rotating shaft portion 7 is rotatably supported with respect to the anode side outer ring 81 and the end portion side outer ring 91. That is, the anode side ball 82 and the end side ball 92 are rolling elements, and the anode side inner ring raceway groove 8c, the anode side outer ring raceway groove 8a, the end side inner ring raceway groove 9c, and the end side outer ring raceway groove 9a are raceway surfaces. The rolling elements are in contact with the raceway surface.

  In order to enable the anode side ball 82 and the end side ball 9 to smoothly roll in a vacuum atmosphere while maintaining conductivity with the anode side inner ring raceway groove 8c and the anode side outer ring raceway groove 8a, the anode side ball 82 and A metallic lubricating film is formed on the surface of the end-side ball 92 or on the surface of the anode-side inner ring raceway groove 8c, the anode-side outer ring raceway groove 8a, the end-side inner ring raceway groove 9c, and the end-side outer ring raceway groove 9a. Is done. The metallic lubricating film will be described later in detail.

  When assembling the anode side ball bearing 8 and the end side ball bearing 9, the anode side inner ring raceway groove 8c and the end side inner ring raceway groove 9c formed on the outer periphery of the rotary shaft portion 7 are connected to the anode side ball 82 and The anode-side outer ring 81 and the end-side ball 92 are opposed to the end-side outer ring 91, and the spacer 11 is disposed between the anode-side outer ring 81 and the end-side outer ring 91 and assembled. Thereafter, the C spacer 12 is inserted between the spacer 11 and the end side outer ring 91.

  When the X-ray tube device 101 operates normally, that is, when X-rays are irradiated, the anode side ball bearing 8 and the end side ball bearing 9 reach a temperature of about 300 ° C. Therefore, in the process of manufacturing the X-ray tube device 101, the anode 212 is rotated while the temperature of the anode side ball bearing 8 and the end side ball bearing 9 is higher than that during normal operation, for example, 400 ° C. The vacuum is evacuated while releasing the stored gas. By carrying out such a process, gas discharge when the X-ray tube apparatus 101 normally operates can be prevented, and as a result, in-tube discharge can be suppressed.

(First embodiment)
The first embodiment of the metallic lubricating film will be described in detail with reference to FIG. The metal lubricating film is formed on the surface of the anode side ball 82 and the end side ball 92, or the anode side inner ring raceway groove 8c, the anode side outer ring raceway groove 8a, the end side inner ring raceway groove 9c, and the end side outer ring raceway. Although formed on at least one of the surfaces of the groove 9a, the case where it is formed on the surfaces of the anode side ball 82 and the end side ball 92 will be described here.

  FIG. 5 is a cross-sectional view of the anode side ball 82 or the end side ball 92 having a metal lubricating film formed on the surface thereof. The anode side ball 82 or the end side ball 92 includes a base material 500 having a spherical shape, a lowermost layer film 501 formed on the base material 500, and an intermediate layer film 502 formed above the lowermost layer film 501. And an uppermost layer film 503 formed above the intermediate layer film 502. Hereinafter, each part will be described. When a metallic lubricating film is formed on the surface of the anode side inner ring raceway groove 8c and the like, the shape of the base material 500 is different, but the other configurations are the same.

  For the base material 500, for example, high-speed tool steel (SKH material: Steel Kougu High-speed) is used so as to sufficiently withstand the load generated when the anode 212 rotates. The main component of high-speed tool steel is Fe. The base material 500 may not be a high-speed tool steel as long as it can sufficiently withstand the load generated when the anode 212 rotates, but in many cases, Fe is the main component.

  For the lowermost layer film 501, for example, Ni is used as a binder between the base material 500 and the intermediate layer film 502. Since Ni reacts with both Fe and Ag, it plays the role of a binder that connects the two. Ni as the lowermost layer film 501 may be present as a binder between the base material 500 and the intermediate layer film 502, and the film thickness may be about 0.05 to 0.1 μm.

  For example, Ag is used for the intermediate layer film 502 so that a sufficient lubricating function can be maintained even at 400 ° C. or higher. Ag has a melting point of 962 ° C., and does not melt even when the temperature of the anode side ball bearing 8 and the end side ball bearing 9 is 400 ° C. or higher. Lubrication function is maintained. In addition, since Ag does not form a solid solution with Fe, which is the main component of high-speed tool steel, when the base material 500 is mainly composed of Fe, if the Ag film is directly formed on the surface of the base material 500, the Ag film is easily peeled off. Can not maintain sufficient lubrication function. In this embodiment, by using Ni for the lowermost layer 501, it is possible to prevent peeling of the Ag film, so that sufficient lubrication can be achieved even when the temperature of the anode side ball bearing 8 and the end side ball bearing 9 is 400 ° C. or higher. The function can be maintained. Ag as the intermediate layer film 502 is only required to maintain a lubrication function when the temperature of the anode side ball bearing 8 and the end side ball bearing 9 is 400 ° C. or higher, and the film thickness is about 0.05 to 0.1 μm. good.

  For the uppermost layer film 503, for example, Pb is used so that the lubricating function can be maintained at 300 ° C. or lower. Pb has a melting point of 327 ° C, and even if the temperature of the anode side ball bearing 8 and the end side ball bearing 9 at the time of normal operation is about 300 ° C, it exists on the lubricated surface without melting, so sufficient lubrication Function is maintained. In the process of manufacturing the X-ray tube device 101, when the temperature of the anode side ball bearing 8 and the end side ball bearing 9 becomes 400 ° C. or more, a part of Pb is melted and peeled off from the lubricating surface. Since the Ag film as the layer film 502 covers the surface of the base material 500, a sufficient lubricating function is maintained. Pb as the uppermost layer film 503 can maintain a lubricating function when the temperature of the anode side ball bearing 8 and the end side ball bearing 9 is about 300 ° C., and even if it melts when the temperature is 400 ° C. or higher, a part of it is lubricated It suffices if it remains on the surface, and the film thickness should be about 0.1 to 0.2 μm.

  As described above, in the present embodiment, the surface of the anode side ball 82 and the end side ball 92, or the anode side inner ring raceway groove 8c, the anode side outer ring raceway groove 8a, the end side inner ring raceway groove 9c, and the end side, as described above. A multilayer lubricating film having a Ni film as the lowermost layer film, an Ag film as the upper layer film of the Ni film, and a Pb film as the upper layer film of the Ag film is formed on at least one of the surfaces of the outer ring raceway groove 9a. With such a configuration, even if the rotating shaft of the anode reaches 400 ° C. or higher, it is possible to suppress a decrease in the lubrication function of the ball bearing.

(Second embodiment)
A second embodiment of the metallic lubricating film will be described in detail with reference to FIG. In the first embodiment, the metallic lubricating film is the three layers of the Ni film of the lowermost layer film 501, the Ag film of the intermediate layer film 502, and the Pb film of the uppermost layer film 503. An upper layer film 503 is formed of the first uppermost layer film 503a and the second uppermost layer film 503b. Since the other configuration of the present embodiment is the same as that of the first embodiment, the following description will be made in detail on the first uppermost layer film 503a and the second uppermost layer film 503b.

  FIG. 6 is a cross-sectional view of the anode-side ball 82 or the end-side ball 92 having a metal lubricating film formed on the surface thereof, as in FIG. In the present embodiment, similarly to the first embodiment, a base material 500, a lowermost layer film 501, and an intermediate layer film 502 are provided, a first uppermost layer film 503a formed above the intermediate layer film 502, and a first uppermost layer film 503a. And a second uppermost layer film 503b formed above the upper layer film 503a.

  For the second uppermost layer film 503b, for example, Pb is used so that the lubricating function can be maintained at 300 ° C. or lower. The reason why Pb is used for the second uppermost layer film 503b is the same as in the first embodiment.

  For the first uppermost layer film 503a, for example, Sn is used as a material that easily reacts with Fe and Pb. Sn reacts easily with Fe, which is the main component of the opposing surface with which the lubricating film is in contact, and is easily alloyed with Pb. Therefore, the Pb film as the second uppermost layer film 503b is transferred to the opposing surface, resulting in sufficient lubrication function. Will be maintained. That is, when a metal lubricating film as shown in FIG. 6 is formed on the surface of the anode side ball 82 and the end side ball 92, the surface of the anode side inner ring raceway groove 8c, etc., which is the opposite surface of the lubricating film Further, Pb peeled off from the lubrication surface is transferred using Sn as the first uppermost layer film 503a as a binder. Of course, when a metallic lubricating film is formed on the surface of the anode side inner ring raceway groove 8c or the like, Pb is transferred onto the surfaces of the anode side ball 82 and the end side ball 92 using Sn as a binder.

  Since the melting point of the alloy of Pb and Sn decreases as the Sn content increases, Sn as the first uppermost layer film 503a is preferably smaller than Pb of the second uppermost layer film 503b, for example, Pb If the film thickness is about 0.1 to 0.2 μm, the film thickness of Sn may be about 0.01 to 0.03 μm.

  As described above, in the present embodiment, the surface of the anode side ball 82 and the end side ball 92, or the anode side inner ring raceway groove 8c, the anode side outer ring raceway groove 8a, the end side inner ring raceway groove 9c, and the end side, as described above. A multilayer having Ni film as the lowermost layer film, Ag film as the upper layer film of the Ni film, Sn film as the upper layer film of the Ag film, and Pb film as the upper layer film of the Sn film on at least one of the surfaces of the outer ring raceway groove 9a A lubricating film is formed. With such a configuration, even if the rotating shaft of the anode reaches 400 ° C. or higher, it is possible to suppress a decrease in the lubrication function of the ball bearing.

(Third embodiment)
A third embodiment of the metallic lubricating film will be described in detail with reference to FIG. In the first embodiment, the metallic lubricating film is a Ni film of the lowermost layer film 501, an Ag film of the intermediate layer film 502, and a Pb film of the uppermost layer film 503. A layer film 502 is formed of the first intermediate layer film 502a and the second intermediate layer film 502b. Since the other configuration of the present embodiment is the same as that of the first embodiment, the following description will be made in detail on the first intermediate layer film 502a and the second intermediate layer film 502b.

  FIG. 7 is a cross-sectional view of the anode-side ball 82 or the end-side ball 92 having a metal lubricating film formed on the surface thereof, as in FIG. In the present embodiment, similarly to the first embodiment, a base material 500, a lowermost layer film 501, and an uppermost layer film 503 are provided, and a first intermediate layer film 502a formed above the lowermost layer film 501 and a first intermediate layer And a second intermediate layer film 502b formed above the layer film 502a.

  For example, Ag is used for the second intermediate layer film 502b so that a sufficient lubricating function can be maintained even at 400 ° C. or higher. The reason why Ag is used for the second intermediate layer film 502b is the same as in the first embodiment.

  For the first intermediate layer film 502a, for example, Cu is used as a material for improving the adhesion between Ni and Ag. Since Cu easily reacts with Ni and easily forms an alloy with Ag, the adhesion between Ni and Ag is improved, and the peeling of Ag as the second intermediate layer film 502b is suppressed. In other words, even if the temperature of the anode side ball bearing 8 and the end side ball bearing 9 becomes higher or the load generated when the anode 212 rotates becomes larger, the peeling of Ag is suppressed. Sufficient lubrication function can be maintained. Note that Cu as the first intermediate layer film 502a may be present as a material for improving the adhesion between Ni and Ag, and the film thickness thereof may be about 0.05 to 0.1 μm.

  As described above, in the present embodiment, the surface of the anode side ball 82 and the end side ball 92, or the anode side inner ring raceway groove 8c, the anode side outer ring raceway groove 8a, the end side inner ring raceway groove 9c, and the end side, as described above. Multilayer having Ni film as the lowermost layer film, Cu film as the upper layer film of the Ni film, Ag film as the upper layer film of the Cu film, and Pb film as the upper layer film of the Ag film on at least one of the surfaces of the outer ring raceway groove 9a A lubricating film is formed. With such a configuration, even if the rotating shaft of the anode reaches 400 ° C. or higher, it is possible to suppress a decrease in the lubrication function of the ball bearing.

  The present invention is not limited to the above embodiment. For example, in the above embodiment, the case where the lubrication film having the same configuration is formed on the anode side ball bearing 8 and the end side ball bearing 9 has been described, but the anode side ball bearing 8 and the end side ball bearing 9 have different configurations. A lubricating film may be formed. That is, in consideration of the fact that the temperature of the anode side ball bearing 8 is higher than that of the end side ball bearing 9, the second embodiment or the third embodiment is used for the anode side ball bearing 8, and the end side The first embodiment may be used for the ball bearing 9.

  Moreover, you may use this invention combining the said embodiment suitably. For example, the second embodiment may be combined with the third embodiment, and a lubricating film including five layers of Ni, Cu, Ag, Sn, and Pb may be used.

  1 X-ray CT device, 100 scan gantry unit, 101 X-ray tube device, 102 rotating disk, 103 collimator, 104 opening, 105 bed, 106 X-ray detector, 107 data collection device, 108 gantry control device, 109 bed control Device, 110 X-ray control device, 120 console, 121 input device, 122 image processing device, 123 storage device, 124 system control device, 125 display device, 210 X-ray tube, 211 cathode, 212: anode, 213 envelope , 214 Excitation coil, 215 Rotating body support, 216 Electron beam, 217 X-ray, 218 Radiation window, 219 Rotating shaft, 220 Container, 300 Fixed portion, 301 Rotating cylindrical portion, 7 Rotating shaft portion, 8 Anode ball bearing, 8a Anode side outer ring raceway groove, 8c Anode side inner ring raceway groove, 81 Anode side outer ring, 82 Anode side ball, 9 end side ball bearing, 9a End side outer ring raceway groove, 9c End side inner ring raceway groove, 91 end side Outer ring, 92 end side ball, 11 spacer, 12 C spacer, 501 Bottom layer film, 502 Middle layer film, 502a First middle Film, 502b second intermediate layer film, 503 uppermost layer, 503a first uppermost layer, 503b a second uppermost layer

Claims (4)

An X-ray tube device comprising an anode that emits X-rays by being irradiated with an electron beam, and an anode rotation driving unit that rotates the anode,
The anode rotation drive unit has rolling elements,
At least one of the raceway surface in contact with the rolling element or the surface of the rolling element has a Ni film as a lowermost layer film, an Ag film formed above the Ni film, and a Pb film formed above the Ag film. It has a multilayer lubricating film ,
Having an Sn film between the Ag film and the Pb film;
The X-ray tube apparatus according to claim 1, wherein the Sn film is thinner than the Pb film . The X-ray tube apparatus according to claim 1,
The X-ray tube apparatus according to claim 1, wherein the Pb film has a thickness of 0.1 to 0.2 μm, and the Sn film has a thickness of 0.01 to 0.03 μm . The X-ray tube apparatus according to claim 1 or 2,
An X-ray tube apparatus comprising a Cu film between the Ni film and the Ag film. Equipped with an X-ray source for irradiating a subject with X-rays, an X-ray detector arranged to face the X-ray source and detecting X-rays transmitted through the subject, and the X-ray source and the X-ray detector A rotating disk rotating around the subject, an image reconstruction device for reconstructing a tomographic image of the subject based on the transmitted X-ray dose detected by the X-ray detector, and reconstruction by the image reconstruction device An X-ray CT apparatus comprising: an image display device that displays the tomographic image that has been obtained;
The X-ray CT apparatus according to claim 1, wherein the X-ray source is the X-ray tube apparatus according to claim 1.

Images