JP4158450B2 - Rolling device and rotating anode X-ray tube - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a rolling device that is preferably used under vacuum and high temperature, and more particularly to a rolling device that is suitable for a rotary anode X-ray tube and the like. The present invention also relates to a rotary anode X-ray tube.
[0002]
[Prior art]
If a lubricant such as lubricating oil or grease is used to lubricate rolling bearings in a vacuum environment or a high-temperature environment, the lubrication function may deteriorate due to evaporation of the lubricant or scattering of the lubricant itself. There is a risk of inconvenience such as contamination.
Therefore, in the environment as described above, conventionally, at least one of the raceway surface of the bearing ring, the rolling surface of the rolling element, and the pocket surface of the cage (the portion in contact with the rolling element) is soft metal. Lubrication was performed by coating a lubricating film made of
[0003]
As the soft metal constituting the lubricating film, silver (Ag), lead (Pb), and the like are known. For example, a rolling bearing used for a rotating anode X-ray tube (an X-ray tube having a rotating anode). , Ag is used when the ambient temperature is 400 to 500 ° C., and Pb is used when the ambient temperature is about 300 ° C. or lower.
On the other hand, in recent years, in rolling bearings for rotating anode X-ray tubes, there are increasing demands for extending the life, improving acoustic characteristics, and shortening the running-in time in the process of assembling the X-ray tube.
[0004]
And in order to satisfy these requirements, attention is focused on improving the wettability (adhesiveness) of Pb to the steel material, and an intermediate layer made of Ag, Bi or the like and a lowermost layer made of Sn, or an intermediate layer made of Sn There has been proposed a rolling bearing in which a lowermost layer made of Cu is formed between an uppermost layer made of Pb and a base material (Japanese Patent Laid-Open No. 7-190067).
[0005]
[Problems to be solved by the invention]
However, although the rolling bearing described in the above publication has excellent wettability of Pb with respect to the base material and has an effect on improving the life in that respect, Sn has a melting point lower than Pb and is likely to evaporate. There was a possibility that durability and acoustic characteristics would deteriorate.
[0006]
In addition, since it is necessary to evaporate a plurality of metals and perform a coating process, there is a problem that a processing process becomes complicated.
Accordingly, the present invention solves the above-mentioned problems of the prior art, and includes a rolling device that has a lubricating film that has excellent adhesion to a base material and is easy to coat, and has excellent life and acoustic characteristics. The issue is to provide. Moreover, this invention makes it a subject to provide the rotating anode X-ray tube excellent in a lifetime and an acoustic characteristic.
[0007]
[Means for Solving the Problems]
In order to solve the above-described problems, the present invention has the following configuration. That is, the rolling device according to the present invention includes an inner member having a raceway surface on the outer surface, and an outer member disposed on the outer side of the inner member, having a raceway surface facing the raceway surface of the inner member. And a plurality of rolling elements arranged so as to be able to roll between the both raceway surfaces, a raceway surface of the inner member, a raceway surface of the outer member, and At least the rolling surface of the rolling element among the rolling surfaces is covered with a lubricating film made of Ag or Pb and formed by an ion mixing method, and the lubricating film is formed between the lubricating film and the base material. It is characterized in that an oxide layer of 0.1 μm or less containing a metal oxide and a metal oxide constituting the main component of the base material is interposed.
The rotating anode X-ray tube of the present invention is characterized by using the rolling device having the above-described configuration.
[0008]
When the oxide layer is interposed, the wettability (adhesion) of the lubricating film with respect to the base material is improved, so that the life and acoustic characteristics of the rolling device become very excellent. Further, since the metal oxide constituting the oxide layer has a high melting point (since it does not easily evaporate at a low melting point like Sn), there is no possibility that durability and acoustic characteristics are deteriorated. The thickness of the oxide layer needs to be 0.1 μm or less, and if it exceeds 0.1 μm, the life and acoustic characteristics of the rolling device may be deteriorated.
[0009]
Further, the method for forming the lubricating film is not particularly limited, but the ion mixing method is most preferable. That is, it is a method of forming an Ag or Pb film by implanting ions such as argon while evaporating Ag or Pb with an electron beam.
If the ion mixing method is used, an Ag or Pb film (lubricating film) is formed, and an oxide layer of 0.1 μm or less is formed between the lubricating film and the base material. A lubricating film and an oxide layer having excellent acoustic characteristics can be easily formed. In addition, since the Ag or Pb film formed by the ion mixing method is superior in durability to the film formed by the conventional ion plating method, the film thickness can be reduced. Since the acoustic characteristics of the rolling device tend to be improved when the thickness of the lubricating film is small, it is preferable to use the ion mixing method also in this respect. Furthermore, if the thickness of the lubricating film is small, the break-in operation time in the process of assembling the rotary anode X-ray tube, for example, can be shortened.
[0010]
The thickness of the lubricating film is preferably 0.1 to 0.5 μm. There exists a problem that durability is inadequate that it is less than 0.1 micrometer. On the other hand, if it exceeds 0.5 μm, there are a problem that the acoustic characteristics are deteriorated and a problem that production time is lowered due to a long running-in time.
Further, the types of steel materials constituting the inner member, the outer member, and the rolling elements are not particularly limited, but SKH4, SUS440C, LNS125, ES1 (alloy component: 0.45% C-13% Cr- Stainless steel such as 0.14% N) is preferred. In particular, in the case of stainless steel, one having an alloy component satisfying C% ≦ 0.05Cr% + 1.41, such as LNS125, ES1, etc. is preferable because it does not generate a huge eutectic carbide.
[0011]
The present invention can be applied to various rolling devices. For example, a rolling bearing, a ball screw, a linear guide device, a linear motion bearing, and the like.
In the present invention, the inner member includes an inner ring when the rolling device is a rolling bearing, a screw shaft when the ball screw is also used, a guide rail when the linear guide device is used, and a linear bearing. In the case, each means an axis. The outer member is an outer ring when the rolling device is a rolling bearing, a nut when it is a ball screw, a slider when it is a linear guide device, and an outer cylinder when it is also a linear bearing. Means each.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of a rolling device according to the present invention will be described with reference to the drawings. FIG. 1 is a partial longitudinal sectional view showing a configuration of a full-ball angular bearing which is an embodiment of a rolling device according to the present invention.
This angular contact ball bearing (nominal number: 708A, inner diameter 8 mm, outer diameter 22 mm, width 7 mm, contact angle 30 °) is disposed between the inner ring 1, the outer ring 2, and the inner ring 1 and the outer ring 2 so as to roll freely. A plurality of balls (rolling elements) 3.
[0013]
The inner ring 1, the outer ring 2, and the ball 3 are all made of SKH4 steel, and the surface of the ball 3 is coated with a lubricating film 3a (outer layer) made of Pb and an oxide layer 3b (inner layer) by an ion mixing method. ing. The thickness of the lubricating film 3a is 0.2 μm, and the thickness of the oxide layer 3b is 0.1 μm. The cage may be provided or may not be provided.
[0014]
The coating process of the lubricating film 3a and the oxide layer 3b by the ion mixing method is performed by an ion beam mixing apparatus as shown in FIG. That is, the workpiece 23 is mounted on the rotary holder 22 (which includes a detector such as ions) in the vacuum chamber 21. Then, the metal M such as Pb and Ag is evaporated by the e-beam evaporator 24, and ions such as argon (activated ions I) are injected from the ion source 25 to the surface of the rotating object to be processed 23. M coating is applied.
[0015]
Here, FIG. 3 shows the results of Auger electron spectroscopy analysis (depth profile) of the lubricating film 3a and the oxide layer 3b formed on the surface of the ball 3 by the ion mixing method. As a comparison, FIG. 4 shows the results of Auger electron spectroscopy analysis of those formed by the ion plating method.
First, a description will be given from the direction of FIG. As can be seen from FIG. 4, the one formed by the ion plating method is a Pb layer, a base material mainly composed of Fe, and an intermediate layer between them (a mixed layer of Pb oxide and Fe oxide). ) Is observed, and oxygen is detected throughout the Pb layer to the base material.
[0016]
On the other hand, FIG. 3 is the same in that a Pb layer, a base material mainly composed of Fe, and an intermediate layer (mixed layer of Pb oxide and Fe oxide) between them are observed. However, oxygen is detected only in the vicinity of the intermediate layer and its interface, which is greatly different from that formed by the ion plating method of FIG. Another significant difference is that the thickness of the intermediate layer is very small.
[0017]
Next, the angular ball bearing of this embodiment as described above was subjected to a rotation test using a vacuum high temperature durability test apparatus as shown in FIG. 5, and its durability was evaluated.
This testing machine includes a rotating shaft S supported by a test bearing J, a motor M that rotates the rotating shaft S, a heater H that heats the rotating shaft S, a flange S1 that forms a vacuum chamber, and walls S2 and S3. And a thermocouple T for detecting the temperature of the test bearing J. The rotating shaft S is also supported by a bearing indicated by reference numeral 18 in addition to the test bearing J. Reference numeral K denotes a heater cable that connects the heater H and a power source.
[0018]
The end of the rotating shaft S on the motor M side is disposed in a housing 15 installed on the outside (atmosphere side) of the flange S1. Since the inside of the housing 15 is sealed by the magnetic seal unit 16, it is in a vacuum. In the housing 15, the end of the rotary shaft S and the rotary shaft of the magnetic seal unit 16 are connected. The rotating shaft of the motor M installed on the atmosphere side is connected to the rotating shaft of the magnetic seal unit 16 by a coupling 17.
[0019]
A torque lever L is attached to the housing JH of the test bearing J, and this torque lever L is connected to the torque detector 19. The torque detector 19 includes a leaf spring B with a strain gauge, and the torque applied to the test bearing J is detected by the strain gauge.
The test conditions are an axial load of 30 N, a rotational speed of 10000 rpm, a temperature of 300 ° C., and a degree of vacuum of 1 × 10 ⁻⁴ Pa or less. The time until the detected torque value of the test bearing J became five times the initial value was regarded as the life, and the rotation test was performed 5 times, and the life was evaluated based on the average value. In addition, the numerical value of the life described below (including the life described in the graph of FIG. 6 to be described later) is set to 1 as the life of the angular ball bearing including a ball in which a lubricating film and an oxide layer are formed by an ion plating method. The relative value is shown in the case. The structure of this angular ball bearing (hereinafter referred to as a comparative example) is the same as that of the above-described angular ball bearing of the present embodiment except that a ball lubricating film and an oxide layer are formed by an ion plating method.
[0020]
As a result of the durability test, the angular ball bearing of the present embodiment has a life of 2.8, which is significantly superior to that of the comparative example.
Further, as a result of examining the relationship between the thickness of the oxide layer and the life of the bearing, as shown in the graph of FIG. 6, the life was excellent when the thickness of the oxide layer was 0.1 μm or less. Thus, it was found that the durability of the bearing is excellent when the thickness of the oxide layer analyzed by Auger electron spectroscopy is 0.1 μm or less.
[0021]
In addition, this embodiment shows an example of this invention and this invention is not limited to this embodiment.
For example, in the present embodiment, the angular ball bearing has been described as an example, but the rolling device of the present invention can be applied to various rolling bearings. For example, radial rolling bearings such as deep groove ball bearings, self-aligning ball bearings, cylindrical roller bearings, tapered roller bearings, needle roller bearings, and self-aligning roller bearings, and thrust types such as thrust ball bearings and thrust roller bearings This is a rolling bearing.
[0022]
Further, in the present embodiment, the rolling bearing is exemplified as the rolling device, but the rolling device of the present invention can be applied to various other types of rolling devices. For example, the present invention can be suitably applied to other rolling devices such as a linear guide device, a ball screw, and a linear motion bearing.
[0023]
【The invention's effect】
As described above, the rolling device of the present invention has a lubricating film that has excellent adhesion to the base material and is easy to coat, and has excellent life and acoustic characteristics. Moreover, the rotating anode X-ray tube of the present invention has excellent life and acoustic characteristics.
[Brief description of the drawings]
FIG. 1 is a partial longitudinal sectional view showing a configuration of an angular ball bearing which is an embodiment of a rolling device according to the present invention.
FIG. 2 is a conceptual diagram showing a configuration of an ion beam mixing apparatus.
FIG. 3 is a depth profile showing an Auger electron spectroscopic analysis result of a lubricating film and an oxide layer formed by an ion mixing method.
FIG. 4 is a depth profile showing the results of Auger electron spectroscopy analysis of a lubricating film and an oxide layer formed by an ion plating method.
FIG. 5 is a schematic view of a vacuum high temperature durability test apparatus for evaluating the durability of a rolling bearing.
FIG. 6 is a graph showing the correlation between the thickness of the oxide layer and the life of the bearing.
[Explanation of symbols]
1 Inner ring 2 Outer ring 3 Ball 3a Lubricating film 3b Oxidized layer

Claims (9)

An inner member having a raceway surface on the outer surface, an outer member having a raceway surface opposite to the raceway surface of the inner member and disposed outside the inner member, and rolling between the raceway surfaces A rolling device comprising a plurality of freely arranged rolling elements,
Of the inner member raceway surface, the outer member raceway surface, and the rolling element rolling surface, at least the rolling surface of the rolling element is made of Ag or Pb and formed by an ion mixing method. An oxide layer of 0.1 μm or less containing a metal oxide constituting the lubricating film and a metal oxide constituting the main component of the base material between the lubricating film and the base material. A rolling device characterized by being interposed.   The rolling device according to claim 1, wherein the lubricating film has a thickness of 0.1 to 0.5 μm.   The rolling device according to claim 1, wherein the base material is stainless steel.   The rolling device according to claim 3, wherein the stainless steel is SKH4 or SUS440C.   The rolling device according to claim 3, wherein the stainless steel is an alloy satisfying a formula of C% ≦ 0.05 Cr% + 1.41. The rolling device according to claim 1, wherein the rolling device is used at a degree of vacuum of 1 × 10 ⁻⁴ Pa or less.   It is a rolling bearing, The rolling device as described in any one of Claims 1-6 characterized by the above-mentioned.   The rolling device according to any one of claims 1 to 6, wherein the rolling device is a full ball bearing. A rotary anode X-ray tube using the rolling device according to claim 7 or 8.

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