JP2017162555A - Rotary anode x-ray tube device and x-ray imaging apparatus using rotary anode x-ray tube device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce damage to the inner surface of a bearing box, by reducing friction between the bearing outer ring and bearing box, upon occurrence of creep phenomenon.SOLUTION: A rotary anode X-ray tube device has a negative electrode releasing thermal electrons, a positive electrode opposed to the negative electrode, and a bearing for supporting the positive electrode rotatably. The bearing has a bearing inner ring connected mechanically with the negative electrode, a plurality of rolling elements arranged on the outer periphery of the bearing inner ring, a bearing outer ring provided farther outside than the plurality of rolling elements, and a bearing box for supporting the bearing outer ring. Surface roughness of the inner surface of the bearing box, facing the outer peripheral surface of the bearing outer ring, is differentiated from the surface roughness of the outer peripheral surface of the bearing outer ring. An X-ray imaging apparatus using the rotary anode X-ray tube device is also provided.SELECTED DRAWING: Figure 7

Description

  The present invention relates to a rotary anode type X-ray tube apparatus and an X-ray imaging apparatus using the same.

  An X-ray imaging apparatus including an X-ray CT (Computed Tomography) apparatus irradiates a subject with X-rays generated by an X-ray tube apparatus, and detects an X-ray dose transmitted through the subject with an X-ray detector. An X-ray image is generated based on the detection result of the X-ray detector, and the X-ray image is displayed on a display device, for example. The X-ray tube device has a configuration in which an X-ray tube for generating X-rays is housed in a housing filled with insulating oil. The X-ray tube includes a cathode that emits thermoelectrons, A structure is provided in which a positive electrode disposed opposite to the cathode and collided with thermoelectrons emitted from the cathode and generating X-rays from the surface is housed in a vacuum vessel.

  If the thermoelectrons emitted from the cathode continue to collide with the same location of the anode, the portion is overheated and damaged. In order to suppress such damage due to overheating, the anode is configured to rotate, and a portion where the thermoelectrons collide with the anode moves based on the rotation. A bearing is used to support the rotating anode, and the bearing includes a shaft that rotates the anode, a rolling element that supports the shaft, and an outer ring that supports the rolling element. The shaft acts as an inner ring with respect to the outer ring. The bearing having such a structure is accommodated in, for example, an axle box.

  In the X-ray imaging apparatus including the X-ray CT apparatus, in the state where the X-ray tube apparatus is used for X-ray imaging, the bearing is used so that the collision part of the thermoelectrons in the anode always moves. The supported anode is rotating. As the shaft rotates, the rolling element revolves in the rotation direction of the inner ring while rotating between the inner ring and the outer ring in a direction opposite to the rotation direction of the inner ring.

  In such a structure, it exists between the outer ring and the rolling element due to rotation or revolution of the rolling element due to, for example, a minute gap existing in a fitting portion between the axle box and the outer ring. There is a possibility that a phenomenon in which the outer ring rotates with respect to the axle box (hereinafter referred to as creep) may occur due to a state in which friction increases. Due to the creep of the outer ring, the inner surface of the axle box in contact with the outer ring is damaged, for example, and wear powder is generated. For example, the wear powder is discharged to the outside of the bearing, which causes a loss of reliability, for example, causing discharge in the X-ray tube apparatus. These are examples of possible possibilities, but if the friction between the outer ring and the rolling element increases, there is a greater possibility that various problems will be caused, and the reliability will be reduced.

  For example, Patent Document 1 discloses a method of preventing creep by fixing an outer ring with a pin or the like. Further, for example, Patent Document 2 discloses a technique for reducing the friction between the outer ring and the axle box when creep occurs by forming a groove between the outer ring and the axle box and filling the lubricant.

JP 2014-086163 A JP 2004-245315 A

  The decrease in the reliability of the X-ray tube apparatus is not a problem of only the X-ray tube apparatus, but a problem of the entire X-ray imaging apparatus. The X-ray tube device is a component that can be used in exchange. However, if an abnormality occurs in the X-ray tube device, the overall efficiency of the X-ray imaging operation is greatly reduced, and the schedule of the imaging operation is greatly upset. This has a great adverse effect on the imaging work. Therefore, it is very important to improve the reliability of the X-ray tube apparatus and improve the reliability of the entire X-ray imaging apparatus.

  The method described in the above-mentioned Patent Document 1 has an advantage over previous X-ray tube devices, but fixing the outer ring may increase the vibration of the rotating body. Good improvement is desirable. Further, the method described in Patent Document 2 has a problem to be solved with respect to supplying an appropriate amount of lubricant filled in the groove over the entire sliding surface. For this reason, further improvement measures for further improving the reliability of the X-ray tube apparatus and further improving the reliability of the entire X-ray imaging apparatus are desired.

  An object of the present invention is to provide an X-ray tube apparatus with further improved reliability or an X-ray imaging apparatus with further improved reliability.

  A rotating anode type X-ray tube device according to the present invention includes a cathode that emits thermoelectrons, an anode disposed opposite to the cathode, and a bearing that rotatably supports the anode. A bearing inner ring mechanically connected to the cathode; a plurality of rolling elements disposed on an outer periphery of the bearing inner ring; a bearing outer ring provided further outside the plurality of rolling elements; and the bearing outer ring. A support for supporting, and the surface roughness of the inner surface of the support opposite to the outer peripheral surface of the bearing outer ring is different from the surface roughness of the outer peripheral surface of the bearing outer ring, It is characterized by that.

  According to the present invention, an X-ray tube apparatus with further improved reliability or an X-ray imaging apparatus with further improved reliability can be obtained.

It is explanatory drawing explaining the structure of the X-ray CT apparatus which is an example of the X-ray imaging apparatus to which this invention was applied. It is explanatory drawing explaining the outline | summary about an example of the X-ray tube apparatus with which this invention was applied. It is explanatory drawing explaining an example of the bearing of the X-ray tube to which this invention was applied. It is sectional drawing seen from the AA direction of the bearing of FIG. It is explanatory drawing which illustrates typically the generation | occurrence | production state of the abrasion powder by a creep phenomenon. It is explanatory drawing which illustrates typically suppression of generation | occurrence | production of the abrasion powder by a creep phenomenon. It is a graph which shows the relationship between the surface roughness of a bearing housing inner surface, and a friction coefficient.

1. 1. Introduction In the form for carrying out the invention shown below (hereinafter referred to as an embodiment), the inventors have studied from various viewpoints and solved various problems. One of the problems to be solved is the contents described in the column of problems to be solved by the above-described invention. The problems to be solved by the embodiments described below, including the contents described in the column of problems to be solved by the invention, will be described in the following embodiments. The embodiments described below also have effects other than the contents described in the column of the effects of the invention described above. The effects of the following embodiments, including the contents described in the column of the effects of the invention described above, will be described in the description of the embodiments.

  In the drawings describing the embodiments of the present invention, substantially the same components are denoted by the same reference numerals. Structures with the same reference sign have substantially the same action and have substantially the same effect. Since it is complicated to repeat the same description regarding the operation and effect of the configuration denoted by the same reference numeral, the description may be omitted.

2. FIG. 1 is an explanatory diagram illustrating a configuration of an X-ray CT apparatus that is an example of an X-ray imaging apparatus to which the present invention is applied. Although the application of the present invention is not limited to the X-ray CT apparatus, since it has a great effect when applied to the X-ray CT apparatus, an embodiment will be described using the X-ray CT apparatus as a representative example.

  The X-ray CT apparatus 100 includes an operation unit 110, a gantry unit 150, and an operation console 130. The gantry unit 150 is provided with a bed 172 on which a subject 170 is placed. In this embodiment, a system control device 112 that performs control and arithmetic processing related to the entire X-ray CT apparatus 100, an image processing device 114 that performs processing for generating an image, and a storage device 116 that stores data are used in this embodiment. Then, it is provided in the operation unit 110. This is an example, and the present invention is not limited to this. However, by providing these apparatuses in the operation unit 110, the overall arrangement relationship of the X-ray CT apparatus 100 is simplified, and the entire X-ray CT apparatus 100 is improved. Furthermore, various effects are born, such as easy inspection and maintenance of the X-ray CT apparatus 100.

  The gantry unit 150 includes a gantry main body 200 for performing X-ray imaging, an X-ray control device 152 and a gantry control device 154 for controlling the operation of the gantry main body 200 based on instructions from the system control device 112, and a bed 172. A couch controller 156 for controlling the operation of the controller based on an instruction from the system controller 112.

  An opening 204 is formed in the center of the gantry main body 200, and the subject 170 is placed in the opening 204 while being placed on the bed 172. A rotating disk 202 whose rotation is controlled by a gantry control device 154 is provided outside the opening 204. The rotating disk 202 or the like is not normally visible from the outside of the gantry body 200, but is shown in FIG. 1 so that the internal configuration can be seen. The rotating disk 202 has an X-ray tube device 300 for irradiating X-rays, a collimator 230 for adjusting the X-ray irradiation angle, and a spatial distribution of X-rays transmitted through the subject 170. X-ray detector 232, data collection device 234 for collecting detected X-ray dose data into digital data, and X-ray tube voltage for supplying X-ray tube voltage and X-ray tube current to the X-ray tube device 300 A power supply device 210 is provided.

  The X-ray tube apparatus 300 and the collimator 230 and the X-ray detector 232 are provided so as to face each other via the subject 170, and the X-ray is transmitted from the X-ray tube apparatus 300 to the subject 170 via the collimator 230. X-rays transmitted through the subject 170 are detected as an X-ray dose by the X-ray detector 232, and the detected X-ray dose is captured as data by the data collection device 234 in the form of digital data. The collimator 230 limits the radiation range of the X-rays emitted from the X-ray tube device 300, and thereby X-rays are emitted to a preset range of the subject 170. The X-ray detector 232 has a large number of X-ray detection elements arranged in the rotation direction of the rotary disk 202 or two-dimensionally arranged in the rotation direction of the rotary disk 202 and the rotation axis direction. The spatial distribution of X-rays transmitted through the examiner 170 is measured. The data collection device 234 collects the X-ray dose detected by the X-ray detector 232 as digital data and sends it to the image processing device 114. A CT image is reconstructed by performing arithmetic processing by the image arithmetic device 132 from the sent measurement data.

  As described above, the operation unit 110 includes the system control device 112, the image processing device 114, and the storage device 116, and further includes, for example, an input device 122 including a keyboard and a pointing device, and an output including a display device and a printer. A device 124 is provided. From the input device 122, information necessary for imaging work, conditions for imaging, and the like are input, and various instructions regarding operation contents are input in the imaging work. For example, on the display device of the output device 124, various information for assisting the input operation is displayed, the input information is displayed, and the reconstructed CT image and other necessary information are displayed.

2. Imaging operation of the X-ray CT apparatus 100 Next, an imaging operation by the X-ray CT apparatus 100 will be described. Imaging conditions input in advance from the input device 122 or the like are stored in, for example, the storage device 116. In the imaging operation, the X-ray control device 152 according to a control signal from the system control device 112 based on the imaging conditions and an operator's instruction. The X-ray tube voltage and the X-ray tube current for generating X-rays are applied from the X-ray tube power supply device 210 to the X-ray tube 320 (see FIG. 2) of the X-ray tube device 300. As will be described below, X-rays are irradiated from an X-ray tube 320 (see FIG. 2) of the X-ray tube device 300, and the irradiated X-rays are applied to the subject 170 within a range and angle defined by the collimator 230. Irradiated. X-rays that have passed through the subject are detected by an X-ray detector 232 having a large number of X-ray detection elements, captured by a data acquisition device 234, and converted into digital data to produce projection data. This projection data represents the distribution of measured transmitted X-rays.

  Based on the imaging conditions, the gantry control device 154 controls the rotation operation and the rotation speed of the rotary disk 202, and the bed control device 156 controls the bed 172. By these controls, for example, an imaging operation is performed according to conditions such as a helical pitch along the body axis direction of the subject 170. The image processing device 114 reconstructs a CT image by performing back projection processing on projection data of various angles sent from the data collection device 234. The CT image obtained by the reconstruction is displayed on the display device of the output device 124 or stored in the storage device 116, for example. In this way, a diagnostic CT image of the subject 170 is taken by the X-ray CT apparatus 100. Although the imaging operation by the X-ray CT apparatus 100 has been described with reference to FIG. 1 as a representative example of the imaging operation, the application of the present invention is not limited to the X-ray CT apparatus 100, and an X-ray image is obtained. The present invention can be widely applied to X-ray imaging apparatuses.

3. FIG. 2 is an explanatory diagram illustrating an outline of an example of the X-ray tube apparatus 300 to which the present invention is applied. An electrical connection mechanism for supplying an X-ray tube voltage, an X-ray tube current, and the like from the X-ray tube power supply device 210 to the X-ray tube 320 is omitted in FIG.

  The inside of the X-ray tube apparatus 300 is filled with insulating oil 302 for maintaining electrical insulation, and the X-ray tube 320 is provided so as to be surrounded by the insulating oil 302. The X-ray tube 320 includes a cathode 330 having a filament (not shown), an anode 350 having a target 352 that receives an electron beam 334 and generates X-rays, and a bearing that rotatably supports a rotating shaft 354 of the anode 350. 360, a coil 342 and a rotor 344 that generate rotational torque for rotating the rotating shaft 354, a sealed container 322 that maintains the inside of the X-ray tube 320 in a vacuum, and a radiation window 304 for irradiating the X-ray 306 It has.

  The inside of the X-ray tube 320 is maintained at a high vacuum of about 10 −5 Pa by the sealed container 322, and the target 352 of the anode 350 is irradiated with the electron beam 334 from the cathode 330 provided inside the X-ray tube 320. X-rays 306 are generated from the portion irradiated with the electron beam 334. The subject 170 is irradiated with the X-ray 306 from the radiation window 304 through the collimator 230. The cathode 330 has a filament (not shown) that emits thermoelectrons, the thermoelectrons are emitted by the filament (not shown), and the emitted thermoelectrons are converged by the focusing electrode 332 to become an electron beam state. Collides with target 352. The electron beam is accelerated by a high voltage from the X-ray tube power supply device 210 to have high kinetic energy, and collides with the target 352 of the anode 350 at high speed. When the electron beam 334 collides, X-rays 306 are generated from the point of the colliding target 352, but the colliding point becomes high temperature. The target 352 is made of a refractory metal such as an alloy of tungsten. However, if the electron beam 334 continues to collide with the target 352, the target part 352 is greatly damaged. The collision position is made to move.

  The target 352 is fixed to a rotating shaft 354, and the rotating shaft 354 is rotatably supported by a bearing 360. Further, the rotational torque generated by the coil 342 and the rotor 344 acts on the rotating shaft 354, and in the state where the X-ray 306 is generated, the target 352 is controlled to always rotate by the rotational torque.

4). An example of the bearing 360 of the X-ray tube 320 to which the present invention is applied An example of the bearing 360 of the X-ray tube 320 to which the present invention is applied will be described with reference to FIGS. 3 and 4. FIG. 3 is an explanatory view for explaining an example of the bearing 360 of the X-ray tube 320 to which the present invention is applied, and FIG. 4 is a sectional view of the bearing 360 shown in FIG. 2, 3, and 4 are diagrams for explaining the configuration and the operational effects, and there are differences in the shape of fine parts between these drawings, but these differences are particularly problematic in explaining the concept. It is not a thing and it is only a small difference in each embodiment. 3 and FIG. 4, in FIG. 3, the rolling element 364 is provided in a groove provided in the bearing inner ring 362, whereas in FIG. 4, the outer periphery without the groove of the bearing inner ring 362 instead of the groove. Although it is described that the rolling elements 364 are provided on the surface, the basic effects are substantially the same in the configurations described in FIGS. 3 and 4.

  In FIG. 3, a target 352 is fixed to one side of the rotating shaft 354, and the bearing inner ring 362 and the rotor 344 of the bearing 360 are mechanically connected to the other side of the rotating shaft 354 via a shaft cap 356 and a heat insulating cap 358. Has been. The target 352 becomes very hot due to the collision of the electron beam 334 as described above. The rotating shaft 354 can be made of a material that can withstand high temperatures, such as titanium alloy, but it is preferable that heat is not transmitted to the rotor 344 and the bearing 360 as much as possible. The heat insulating cap 358 fixed to the other side of the rotating shaft 354 via the shaft cap 356 has an effect of suppressing the heat from the target 352 from being transmitted to the rotor 344 and the bearing 360.

  The bearing 360 includes a bearing inner ring 362, a rolling element 364 and a rolling element 365 provided outside the bearing inner ring 362, a bearing outer ring 366 and a bearing outer ring 367 provided further outside the rolling element 364 and the rolling element 365, A bearing housing 368 that supports the bearing outer ring 366 and the bearing outer ring 367 is provided. In this embodiment, the rolling element 364 and the bearing outer ring 366 are disposed on one side of the bearing inner ring 362 of the bearing 360, and the rolling element 365 and the bearing outer ring 367 are disposed on the other side of the bearing inner ring 362, thereby providing two sets of bearings. A bearing inner ring 362 is rotatably supported by a bearing box 368 by the mechanism. Thus, stable support is possible by supporting by a plurality of bearing mechanisms. A specific operation of the bearing 360 will be described with reference to FIG.

  In FIG. 4, the following description will be made on the assumption that a rotational torque acts on the bearing inner ring 362 and the rotating shaft 354 by the rotor 344 and the bearing inner ring 362 rotates in the direction of the arrow 372. In addition, even if it is embodiment rotated in a reverse direction, an effect is the same. By rotating the bearing inner ring 362 in the direction of the arrow 372, the eight rolling elements 364 arranged on the outer periphery of the bearing inner ring 362 rotate in the direction of the arrow 374, respectively. The number of rolling elements 364 is an example and is not limited to this. However, at least several are necessary. Each rolling element 364 revolves around the outer peripheral surface of the bearing inner ring 362 in the direction of arrow 375 while rotating in the direction opposite to the direction of arrow 372 which is the rotation direction of the bearing inner ring 362.

  Due to the rotation and revolution of each rolling element 364, rotational torque due to friction between each rolling element 364 and the bearing outer ring 366 acts on the bearing outer ring 366. This rotational torque may cause a phenomenon (referred to as creep) in which the bearing outer ring 366 rotates with respect to the inner surface of the bearing housing 368. If the bearing outer ring 366 is fixed to the inner surface of the bearing housing 368 with a sufficiently strong force against the rotational torque due to friction, creep does not occur. However, for example, when the bearing outer ring 366 is fixed to the inner surface of the bearing housing 368 by fitting, the bearing outer ring 366 is fixed to the inner surface of the bearing housing 368 due to the presence of a minute gap in the fitting portion. When the force to be applied is weak, creep is generated in which the bearing outer ring 366 rotates with respect to the bearing housing 368.

  When the bearing outer ring 366 creeps on the inner surface of the bearing housing 368, the inner surface of the bearing housing 368 with which the rolling elements 364 are in contact is damaged and wear powder is generated. This wear powder is discharged outside the bearing 360, causing the X-ray tube 320 to generate a discharge phenomenon. A very high voltage for accelerating the electron beam 334 is applied between the cathode 330 of the X-ray tube 320 and the target 352. By maintaining the inside of the X-ray tube 320 at a high degree of vacuum, the inside of the X-ray tube 320 maintains a high insulating property, but when the above-described metal wear powder is generated, the insulating property is reduced, Causes various problems.

5. About suppression of generation | occurrence | production of the abrasion powder of the bearing housing 368 Next, the suppression countermeasure of the abrasion powder generated by the creep with respect to the inner surface of the bearing housing 368 of the bearing outer ring 366 mentioned above is demonstrated. Wear powder is generated not only by the bearing outer ring 366 but also by creep of the bearing outer ring 367 against the inner surface of the bearing housing 368. The following contents are also effective for suppressing wear powder generated by creep of the bearing outer ring 367, and these have the same basic effects, so that the bearing outer ring 366 and the inner surface of the bearing housing 368 are representatively shown. A description will be given of creep during heating and suppression of the wear powder.

5.1 Generation Mechanism of Wear Powder in Bearing Box 368 FIG. 5 is an explanatory diagram schematically illustrating the state of generation of wear powder due to creep on the inner surface of the bearing box 368 of the bearing outer ring 366. FIG. 5 is an enlarged conceptual view of a contact portion between an outer surface 386 of a bearing outer ring 366 that is a sliding surface of the bearing housing 368 and an inner surface 388 of the bearing housing 368. The bearing outer ring 366 is made of, for example, an SKH material having high wear resistance, and the SKH material is made of, for example, a tungsten-based material or a molybdenum-based material. On the other hand, the bearing housing 368 is made of, for example, an iron-based material that is more wearable than the bearing outer ring 366. When the surface roughness of the outer surface 386 of the bearing outer ring 366 and the inner surface 388 of the bearing housing 368 is relatively close, as shown in FIG. Concavities and convexities on the inner surface 388 of the bearing housing 368 are scraped by the concavities and convexities on the outer surface 386 of the bearing outer ring 366 made of material. Of course, the coefficient of friction at this time increases. Here, the fact that the friction coefficient is large has a deep relationship with the engagement of the unevenness of the inner surface 388 of the bearing housing 368 due to the unevenness of the outer surface 386 of the bearing outer ring 366. Suppression of the unevenness of the inner surface 388 of the bearing housing 368 due to the unevenness of the outer surface 386 of the bearing outer ring 366 and reduction of friction between the outer surface 386 of the bearing outer ring 366 and the inner surface 388 of the bearing housing 368. It has a deep relationship, and it can be seen that the friction coefficient increases due to the occurrence of the biting. Therefore, if the friction coefficient can be reduced, it can be considered that the biting has decreased.

5.2 Suppression of Generation of Wear Powder in Bearing Box 368 FIG. 6 is an explanatory diagram for explaining a mechanism for suppressing generation of wear powder on the inner surface 388 of the bearing box 368 due to unevenness of the outer surface 386 of the bearing outer ring 366. is there. When the surface roughness of the inner surface 388 of the bearing housing 368 is made rougher than the surface roughness of the outer surface 386 of the bearing outer ring 366 having high hardness, the irregularities of the outer surface 386 of the bearing outer ring 366 as shown in FIG. However, the state of being engaged with the unevenness of the inner surface 388 of the bearing box 368 is reduced. As a result, the inner surface 388 of the bearing housing 368 can be prevented from being scraped by the bearing outer ring 366 and generating wear powder. In this case, as a matter of course, the friction coefficient between the outer surface 386 of the bearing outer ring 366 and the inner surface 388 of the bearing housing 368 is a small value.

5.3 Experimental Results Regarding Relationship between Surface Roughness and Friction Coefficient Table 1 shows the friction coefficient measurement when the surface roughness of the outer surface 386 of the bearing outer ring 366 is fixed and the surface roughness of the inner surface 388 of the bearing housing 368 is changed. FIG. 7 is a graph showing the experimental results.

  In this experiment, as an example, the surface roughness Rmax of the outer surface 386 of the bearing outer ring 366 is 1.4 μm as an example, and the surface roughness Rmax of the inner surface 388 of the bearing housing 368 is 2.0 μm, 3.5 μm, or 5.1 μm. The change in the coefficient of friction was measured. Table 1 shows the measurement results, and the graph described based on Table 1 is a graph described as FIG. There are several types of representations for representing the surface roughness. Any representation may be used, but in this experiment, the surface roughness is represented by the maximum height. That is, as an example, only the reference length is extracted from the roughness curve in the average line direction, the distance between the peak line and the valley line of the extracted part is measured, and the surface roughness is represented by a value expressed in μm. .

  When the surface roughness Rmax of the inner surface 388 of the bearing housing 368 is finer than 2.0 μm, the friction coefficient is a large value of 0.30 or more. In this state, it is indicated that the engagement between the unevenness of the outer surface 386 of the bearing outer ring 366 and the unevenness of the inner surface 388 of the bearing housing 368 occurs. When the surface roughness Rmax of the inner surface 388 of the bearing housing 368 is 3.5 μm, the friction coefficient is reduced to 0.25, which indicates that the above-described engagement is reduced. Further, this reduction in the coefficient of friction means suppression of generation of wear powder by the inner surface 388 of the bearing housing 368.

  Next, when the surface roughness Rmax of the inner surface 388 of the bearing housing 368 is 5.1 μm, the friction coefficient is reduced to 0.20. This state means that the above-mentioned biting is very little or hardly occurs. This state is the state described above with reference to FIG. 6 and represents that almost no abrasion powder is generated from the inner surface 388 of the bearing housing 368. From the viewpoint of reducing damage to the inner surface 388 of the bearing housing 368 when a creep phenomenon occurs, it is desirable to set the value of the friction coefficient μ to 0.2 or less. Therefore, it is more preferable that the surface roughness Rmax of the surface facing the bearing outer ring 366 is 5.1 μm or more.

5.4 About the Effects of the Present Embodiment As described with reference to FIGS. 5 to 7, the surface roughness of the outer surface 386 of the bearing outer ring 366 and the surface roughness of the surface facing the outer surface 386 of the bearing outer ring 366. 6, it is possible to suppress the biting between the outer surface 386 of the bearing outer ring 366 and its contact surface as described in the example in FIG. 6 and to suppress the generation of wear powder. Become. When the difference in surface roughness is about 2.0 μm or more, the friction coefficient of the contact surface is reduced, which leads to suppression of biting on the contact surface. In this case, for example, when the surface roughness of the outer surface 386 of the bearing outer ring 366 is 1.4 μm, the surface roughness of the surface in contact with the outer surface 386 of the bearing outer ring 366 is about 3.5 μm.

  By setting the difference in surface roughness between the outer surface 386 of the bearing outer ring 366 and the contact surface thereof to be about 3.5 μm or more, the effect of suppressing biting on the contact surface is further increased. In this case, for example, when the surface roughness of the outer surface 386 of the bearing outer ring 366 is 1.4 μm, the surface roughness of the surface in contact with the outer surface 386 of the bearing outer ring 366 is about 5.1 μm. The friction coefficient described in the above item is close to 0.2.

  It is preferable to make the surface roughness of the surface in contact with the outer surface 386 of the bearing outer ring 366 rougher than the surface roughness of the outer surface 386 of the bearing outer ring 366. That is, since the bearing outer ring 366 contacts and holds the rolling elements 364 and 365 of the rotary bearing, it is preferable to use a hard material such as an SKH material. On the other hand, since the bearing housing 368 that contacts the outer surface 386 of the bearing outer ring 366 functions to fix and support the bearing outer ring 366, it is desirable to use a material softer than the bearing outer ring 366, such as an iron-based material. From these viewpoints, it is preferable to make the surface roughness of the surface contacting the outer surface 386 of the bearing outer ring 366 rougher than the surface roughness of the outer surface 386 of the bearing outer ring 366 as in the present embodiment.

6). Regarding Other Embodiments In a general conventional idea, the bearing housing 368 functions to fix and support the bearing outer ring 366, and therefore, between the outer surface 386 of the bearing outer ring 366 and the inner surface 388 of the bearing housing 368. The idea is to take measures to prevent creep. However, in such a conventional way of thinking, once the creep phenomenon occurs, friction powder is generated. As described above, a high voltage, for example, a high voltage of several tens of thousands of volts, is applied between the cathode 330 and the target 352, which causes a serious problem when metal powder is generated. Therefore, the idea of suppressing the generation of metal powder as much as possible even when the creep phenomenon occurs is extremely important. Even if the above-mentioned Example is a case where creep generate | occur | produces, generation | occurrence | production of the metal powder by biting of the micro unevenness | corrugation of a contact surface can be suppressed, and there exists an effect. Such an idea is different from the conventional idea.

  Further, in addition to the above embodiment, the solid lubricant is applied to the contact surface between the outer surface 386 of the bearing outer ring 366 and the inner surface 388 of the bearing housing 368, thereby further reducing damage to the inner surface 388 of the bearing housing 368. can do. For example, molybdenum may be applied as the solid lubricant. Applying the lubricant between the outer surface 386 of the bearing outer ring 366 and the inner surface 388 of the bearing housing 368 in this way is completely opposite from the viewpoint of suppressing creep. However, as described above, if an attempt is made to prevent creep from occurring at all, a serious problem will occur if creep occurs. The basic background of the present application is to change the way of thinking so that even if creep occurs, a configuration that does not generate wear powder is used. This is an unprecedented idea.

DESCRIPTION OF SYMBOLS 100 ... X-ray CT apparatus, 110 ... Operation part, 112 ... System control apparatus, 114 ... Image processing apparatus, 116 ... Memory | storage device, 122 ... Input device, 124 ... Output device 150... Gantry unit 152. X-ray control device 154. Gantry control device 156... Bed control device 170 170 subject 172. ... Gantry body 202 ... Rotary disk 204 ... Opening 210 ... X-ray tube power supply device 230 ... Collimator 232 ... X-ray detector 234 ... Data collection Device: 232 ... X-ray detector, 234 ... Data collection device, 300 ... X-ray tube device, 302 ... Insulating oil, 304 ... Radiation window, 306 ... X-ray, 320 ... X-ray tube, 322 ... Airtight container, 330 ..Cathode, 332... Converging electrode, 334... Electron beam, 342... Coil, 344... Rotor, 350 .. Anode, 352. ... Shaft cap, 360 ... Bearing, 358 ... Heat insulation cap, 362 ... Bearing inner ring, 364 ... Rolling element, 366 ... Bearing outer ring, 368 ... Bearing box, 372 Arrows, 374 ... arrows, 375 ... arrows, 386 ... outer surface, 388 ... inner surface.

Claims (10)

A cathode that emits thermoelectrons, an anode disposed opposite to the cathode, and a bearing that rotatably supports the anode;
The bearing includes a bearing inner ring mechanically connected to the cathode, a plurality of rolling elements disposed on an outer periphery of the bearing inner ring, and a bearing outer ring provided further outside the plurality of rolling elements, A support for supporting the bearing outer ring,
The rotary anode type X is characterized in that the surface roughness of the inner surface of the support opposite to the outer peripheral surface of the bearing outer ring is different from the surface roughness of the outer peripheral surface of the bearing outer ring. Tube device.   2. The rotary anode X-ray tube apparatus according to claim 1, wherein the surface roughness of the inner surface of the support opposite to the outer peripheral surface of the bearing outer ring is made rougher than the surface roughness of the outer peripheral surface of the bearing outer ring. A rotary anode type X-ray tube device characterized by that.   The rotary anode X-ray tube apparatus according to claim 2, wherein the surface roughness of the inner surface of the support opposite to the outer peripheral surface of the bearing outer ring is made rougher than the surface roughness of the outer peripheral surface of the bearing outer ring. As a result, the friction coefficient between the outer peripheral surface of the bearing outer ring and the inner surface of the support opposite to the outer peripheral surface of the bearing outer ring is 0.25 or less. Rotating anode X-ray tube device.   4. The rotary anode X-ray tube device according to claim 3, wherein the surface roughness of the inner surface of the support body facing the outer peripheral surface of the bearing outer ring is made rougher than the surface roughness of the outer peripheral surface of the bearing outer ring. Thus, the friction coefficient between the outer peripheral surface of the bearing outer ring and the inner surface of the support opposite to the outer peripheral surface of the bearing outer ring is 0.20 or less. Rotating anode X-ray tube device. The rotary anode X-ray tube device according to claim 1,
The support for supporting the bearing outer ring is a bearing box,
The difference in surface roughness of the inner surface of the bearing housing facing the outer peripheral surface of the bearing outer ring with respect to the surface roughness of the outer peripheral surface of the bearing outer ring is about 2.0 μm or more, A rotary anode type X-ray tube device characterized in that the surface roughness of the inner surface of the bearing housing is rougher than the surface roughness of the outer peripheral surface.   2. The rotary anode X-ray tube apparatus according to claim 1, wherein the surface roughness of the inner surface of the bearing box facing the outer peripheral surface of the bearing outer ring is different from the surface roughness of the outer peripheral surface of the bearing outer ring. Is a rotating anode type X-ray tube device, characterized in that it is about 3.5 μm or more.   The rotary anode X-ray tube apparatus according to any one of claims 1 to 6, wherein the outer surface of the bearing outer ring has a surface roughness of about 1.4 µm, whereas the inner surface of the support body. The rotary anode type X-ray tube apparatus is characterized by having a surface roughness of 5.1 μm or more.   The rotary anode type X-ray tube device according to any one of claims 1 to 7, wherein a solid lubricant is provided on a sliding surface between an outer peripheral surface of the bearing outer ring and an inner surface of the support. A rotating anode type X-ray tube device.   An X-ray imaging apparatus using a rotating anode X-ray tube apparatus, characterized in that the rotating anode X-ray tube apparatus according to claim 1 is used. A gantry body, a system control device, an image processing device, an input device and an output device,
The gantry body includes a rotating disk, an X-ray tube device provided with the rotating disk, a collimator, an X-ray detector, and an X-ray tube power supply device,
An X-ray imaging using a rotary anode X-ray tube device, characterized in that the rotary anode X-ray tube device according to one of claims 1 to 8 is used as the X-ray tube device. apparatus.

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