JPS60202643A - Rotary anode x-ray tube - Google Patents

Abstract

PURPOSE:To prevent any damage to ball bearings used to rotate the anode target by forming minute cracks resulting from intergranular corrosion on the surface of a fixing shaft for supporting the ball bearings. CONSTITUTION:The anode target 3 of an X-ray tube is attached to a cylinder 4 also working as a rotor and the cylinder 4 is supported by a fixing shaft 7 through angular-contact-type ball bearings 5 and 6. A coil spring 9 and a slider 9 are attached inside the fixing shaft 7 and the cylinder 4 is rotated by applying pressure to the inner side of the ball bearing 6. The entire outer surface 12 of the fixing shaft 7 not only its area touching the slider 9 and the ball bearing 6, is subjected to chemical treatment performed utilizing intergranular corrosion to form minute cracks 13 and then nonvolatile lubricant 14 such as molybdenum disulfide is caused to penetrate the cracks 13. Therefore, it is possible to prevent any damage to the bearings 5 and 6 efficiently by providing it with both lubricative property and shock resistance.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a rotating anode X-ray tube, and more particularly to an X-ray tube in which a fixed shaft supporting a bearing and its preload device has vibration damping and lubrication functions.

[Background of the invention]

Generally, a rotating anode X-ray tube is constructed as shown in FIG. 1, in which a cathode 2 and an anode target 3 are disposed facing each other in a vacuum envelope 1. The target 3 and the cylinder 4 are freely supported by an angular contact type ball bearing 5.6 whose inner and outer axes are movable relative to each other in the axial direction. The ball bearings 5 and 6 are arranged and fitted at intervals to a fixed shaft 7 whose one end is fixed to a fixed part 8, and a cylinder 4 is fitted to the outer cylinder of the ball bearings 5 and 6.
are fitted and fixed. Further, a coil spring 9 and a slider 10 are loosely fitted to the fixed shaft 7, and the spring force of the coil spring 9 is applied as a preload to the inner ring side of the ball bearing 6 via the slider 9.

When such an X-ray tube is operated, an electron beam is irradiated from the cathode 2 to the target 3 when X-rays are generated.
Target 3 is heated to an average temperature of at least 1200°C. Although the target 3 is placed in a vacuum, most of this heat is radiated to the outside by radiation heat transfer, but some of the heat in the target 3 is transferred to the cylinder 4, ball bearings 5, 6, and fixed shaft 7 by conduction. transmitted to. However, since the temperature of the cylinder 4 is considerably higher than that of the fixed shaft 7, the outer ring of the ball bearing 6, which is fixed to the first cylinder 4, moves in the axial direction due to the elongation of the cylinder 4 due to heat. In this case, since the spring force of the coil spring 9 acts on the inner ring of the ball bearing 6 via the slider IO, the slider IO and the inner ring of the ball bearing 6 also try to move in the axial direction following the outer ring. and fixed shaft7. Movement is hindered by the action of dry friction between the inner ring of the ball bearing 6 and the fixed shaft 7. In addition, the fixed shaft 7 may vibrate due to vibrations due to thermal imbalance caused by mechanical contact between the target 3 and the cylinder 4, which rotate at high speed, or due to rolling of the balls of the bearings 5 and 6, causing vibrations between the fixed shaft 7 and the slider 10, etc. The fixed shaft 7 rubs due to sliding friction, which promotes galling. As a result, the balls of the ball bearing 6 dance, causing damage to the ball bearing 6.

In order to reduce the friction of this fixed shaft 7, the shaft surface may be coated with a solid lubricant such as molybdenum disulfide, or the shaft may be surface treated by nitrogen absorption method to coat it with an extremely thin layer of soft metal. In both cases, the adhesion of the lubricant is low, and the lubricating force decreases at a large rate over time due to vibration sliding, etc., and there are problems in terms of durability and vibration damping properties.

[Purpose of the invention]

An object of the present invention is to provide a rotary anode X-ray tube that can be operated with a simple structure and has good operation by effectively utilizing the fixed shaft for forming surface cracks due to intergranular corrosion.

[Summary of the invention]

As a means of eliminating galling caused by dry friction between the slider or ball bearing and the fixed shaft, the present invention forms fine surface cracks on the surface of the fixed shaft and then fills the cracks with a non-volatile lubricant. This is what I did.

[Embodiments of the invention] Hereinafter, the invention will be described in detail with respect to one embodiment shown in the drawings.

In FIG. 1, the known intergranular corrosion phenomenon occurs in the outer surface layer 12 of the fixed shaft 7, not only in the area 11 where the slider 9 and the ball bearing 6 contact and slide on the fixed shaft 7, but also in the entire fixed shaft 7. By chemical treatment using .

Fine cracks 13 as shown in FIG. 2 are formed.

Next, a non-11FF-filled lubricant I4 such as molybdenum disulfide is sufficiently rubbed on the surface of the fixed shaft 7, and the lubricant 1
4 into the cracks of fixing 7.

When the rotating anode X-ray tube is rotated at high speed under high vacuum to generate X-rays, the fixed shaft 7 bends and vibrates due to the transfer of the balls of the unbalanced ball bearings 5 and 6 of the target 3 and cylinder 4. , the contact sliding e and friction of the splitting interface of the splitting h I 3 act to suppress the vibration of the fixed 4i 1117, and furthermore, the non-volatile lubricant 14 on the surface of the fixed shaft 7 prevents the slider 10 and the ball bearing 6. A lubricating film is formed between the two to provide a lubricating effect. In the chemical treatment due to the intergranular corrosion phenomenon, countless cracks I3 are densely formed on the surface of the fixed shaft 7, so the lubricating effect and damping effect are significantly increased.
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Therefore, when the cylinder 4 expands due to thermal action and the outer ring of the ball bearing 6 moves in the axial direction, both the inner ring and the slider 10 receive the spring force of the coil spring 9 and smoothly follow the movement without galling. do.

FIG. 3 shows another embodiment of the invention. The difference from FIG. 2 is that after the fixed shaft 7 was subjected to the above-mentioned chemical treatment, the upper layer of the surface layer, which had suffered intergranular corrosion, was removed using a lathe or the like. In the upper layer of the surface layer where the density of 9-cracks is high due to this cutting process, the surface strength is low in places where the distance between the cracks is small or where the cracks occur horizontally, so it is difficult to use a cutting tool such as a lathe. When scraping, a phenomenon occurs in which members located at a depth greater than the specified dimensions are also removed. Therefore, as shown in FIG. 3, the surface of the fixed shaft 7 after cutting has dents I5 and 16 whose opening area is larger than the opening area of the original crack due to intergranular corrosion.

The nonvolatile lubricant 17 is sufficiently rubbed onto the surface of the fixed shaft 7 in this state.

Since the proportion of the opposing contact area between the shaft 7 and the lubricant 17 is large, the lubrication performance is further improved. Furthermore, since the recesses 15 and 16 are large, the amount of lubricant deposited increases, and the stability of lubrication is improved. Furthermore, the deep part of the crack 13 in the fixed shaft 7 remains as it is, and the contact and sliding friction at the crack interface is greater in the deeper part than in the surface opening where the opposing interface is closer, so the vibration of the fixed shaft 7 is suppressed. The effect is not impaired either.

〔Effect of the invention〕

According to the present invention, a lubricating function and a vibration damping function can be added at the same time between the fixed shaft of the rotating anode X-ray tube and the slider or ball bearing, so that damage to the bearing can be prevented and efficient operation can be performed. Can be done.

[Brief explanation of drawings]

FIG. 1 is a front cross-sectional view of a rotating anode X-ray tube, FIG. 2 is a cross-sectional view of one embodiment of the present invention corresponding to the section ■ in FIG. 1, and FIG. 3 is a cross-sectional view of another embodiment. 4...Cylinder, 5, 6...Ball bearing, 7...Fixed shaft,
10...Slider, 13...Cracked, 14.17...
・Non-volatile lubricant, 15.16...dent. Figure 1

Claims (1)

[Claims] 1. A ball bearing having a rotating shaft for rotating an anode target, a fixed shaft supporting the ball bearing, and a coil spring and a slider loosely fitted to the fixed shaft to support the ball bearing. In an X-ray tube consisting of a preload device that applies thrust force to and applying a non-volatile lubricant to the surface layer,
Is there solid moisture on the outer surface of the fixed shaft? A rotating anode X-ray tube characterized by forming an ltM. 2. In claim 1, after the surface layer portion of the fixed shaft is subjected to intergranular corrosion, the outer surface portion is removed by approximately several 10 μm to form irregularities, and the non-volatile lubricant is applied to the concave portions. A rotating anode X-ray tube characterized by being embedded with.