JP2005321006A - Rolling bearing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rolling bearing device having a structure capable of effectively preventing generation of creep and fretting. <P>SOLUTION: The rolling bearing device 100 is provided with two O-ring grooves 21b formed on an outer peripheral face of an outer ring 21 so as to be separated from each other in the axial direction at the approximately same interval as the width of a rolling element 25, O-rings 33 made of fluorine rubber fitted to the O-ring grooves 21b, respectively, and grease 31 sealed inside the rolling bearing device 100 and containing a fluorine thickening agent. The two O-rings 33 have hardness of Hs70, and are fitted to a housing 35 with a collapse allowance d 20 to 40% of the wire diameter D of the O-rings 33. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a rolling bearing device, for example, a rolling bearing device suitable for use in supporting a screw shaft or the like of a dry vacuum pump used in semiconductor equipment.

  Rolling bearing devices that support screw shafts and the like of dry vacuum pumps used in semiconductor equipment are used under extremely severe conditions, and are therefore replaced every two to three years. In order to facilitate the replacement work of the rolling bearing device, the fitting between the inner ring and the shaft and the fitting between the outer ring and the housing are carried out by a so-called dead fit or clearance fit with no interference allowance. ing.

  Therefore, when the inner ring rotates together with the shaft under a load, relative rotation of the outer ring with respect to the housing that occurs as the shaft rotates, so-called creep, wear due to repeated micro-slip between the outer ring and the housing, so-called fretting occurs. Easy to do. Creep force and the like increase in proportion to the load applied to the rolling bearing device, and therefore, creep and fretting damage tend to occur in proportion to the magnitude of the load.

  As a technique for preventing such creep and fretting, a technique in which a pin is implanted in an outer ring and the pin is engaged with a slot provided in a housing is known (for example, see Patent Document 1). .

As shown in FIG. 4, a rolling bearing device (an anti-creep bearing) 10 includes an outer ring 3, an inner ring 4, a plurality of balls 5 that are rolling elements, and a cage 6 that holds the balls 5 in a rollable manner. And a shield plate 7, and a grease 8 is sealed inside a bearing 10 sealed by the shield plate 7. Then, the pin 1 is planted in a hole 3 a radially opened on the outer peripheral surface of the outer ring 3, and the pin 1 is engaged with the groove 2 a formed in the housing 2, whereby the outer ring 3 is rotated relative to the housing 2. Is prevented.
Japanese Utility Model Publication No. 3-78131 (FIG. 2)

  However, if the rolling bearing device 10 having such a pin 1 is used under severe conditions such as supporting a screw shaft of a dry vacuum pump, the pin 1 is likely to be damaged. The rolling bearing device 10 itself may be seriously damaged, or important parts arranged in the vicinity of the rolling bearing device 10 such as a screw shaft or a screw of a dry vacuum pump may be damaged, and the rolling bearing device 10 is incorporated. There was a possibility that the function of the device (for example, a dry vacuum pump) could not be maintained.

  The present invention has been made in view of the above-described circumstances, and an object thereof is to provide a rolling bearing device having a structure capable of effectively preventing the occurrence of creep and fretting.

In order to achieve the above-described object, a rolling bearing device according to the present invention is characterized by the following (1) and (2).
(1) an inner ring having an outer peripheral surface on which an inner ring raceway surface is formed;
An outer ring having an inner peripheral surface on which an outer ring raceway surface is formed;
A plurality of rolling elements arranged to be freely rollable in the circumferential direction between the inner ring raceway surface and the outer ring raceway surface;
A pair of annular sealing devices attached to one of the inner ring and the outer ring so as to sandwich the rolling element;
Two O (O) ring grooves formed on the outer peripheral surface of the outer ring and spaced apart in the axial direction at substantially the same interval as the width of the rolling elements;
Fluorine rubber O-rings mounted in the O-ring grooves,
A rolling bearing device comprising:
Grease containing a fluorinated thickener is enclosed.
(2) The rolling bearing device according to (1), wherein the O-ring has a hardness of Hs70, and a crushing cost of the O-ring that is crushed when the rolling bearing device is mounted on a housing is the O-ring. 20% to 40% of the wire diameter of the ring.

According to the rolling bearing device of the above (1), two O-ring grooves formed on the outer circumferential surface of the outer ring and spaced apart in the axial direction at substantially the same interval as the width of the rolling element, and the O-ring grooves are respectively mounted. And the O-ring made of fluorine-based rubber, the rolling bearing device is fitted into the housing by being press-fitted into the housing with the O-ring being crushed in the radial direction. Thereby, the radial vibration motion acting on the rolling bearing device is attenuated, and the occurrence of creep and fretting is prevented.
Further, according to the rolling bearing device of the above (1), since the O-ring is made of a fluorine-based material, the O-ring does not deteriorate even when exposed to vacuum. Moreover, the O-ring made of a fluorine-based material does not react with the reactive gas, and even when the rolling bearing device is used for a vacuum pump that sucks the reactive gas, the O-ring does not deteriorate and is stably sealed. Can do.
Further, according to the rolling bearing device of (1), the two O-ring grooves are formed to be spaced apart in the axial direction at substantially the same interval as the width of the rolling element. The wall thickness of the film does not become extremely thin, and sufficient strength is ensured.
Further, according to the rolling bearing device of (1) above, since the grease sealed in the rolling bearing device contains a fluorine-based thickener, the rolling bearing device is used in a vacuum pump and exposed to vacuum. However, the evaporation of the grease component from the grease is extremely small, and therefore environmental degradation due to the deterioration of the grease and the evaporation of the grease component is prevented.
Therefore, the rolling bearing device of the above (1) is used stably because the performance does not deteriorate for a long time even under severe use conditions such as support of the screw shaft of the dry vacuum pump. Therefore, the life of the rolling bearing device can be extended, and the reliability of the device in which the rolling bearing device is incorporated can be improved.
Further, according to the rolling bearing device of (2) above, the O-ring has a hardness of Hs70, and the crushing cost of the O-ring that is crushed when the rolling bearing device is mounted on the housing is the O-ring diameter. Since it is 20% to 40%, the outer ring is held in the housing with a force larger than the creep force acting on the outer ring, and the occurrence of creep and fretting is prevented, thereby extending the life of the rolling bearing device.

  According to the rolling bearing device of the present invention, the occurrence of creep and fretting is prevented even under severe usage conditions such as support of the screw shaft of a dry vacuum pump, etc., and the life of the rolling bearing device is prolonged. Can do. Moreover, this can improve the reliability of the apparatus in which the rolling bearing device of the present invention is incorporated.

  The present invention has been briefly described above. Furthermore, the details of the present invention will be further clarified by reading through the best mode for carrying out the invention described below with reference to the accompanying drawings.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of the invention will be described in detail with reference to the drawings.

(First embodiment)
FIG. 1 is a longitudinal sectional view of an upper half portion of a rolling bearing device according to a first embodiment of the present invention. As shown in FIG. 1, the rolling bearing device 100 according to the present invention includes an outer ring 21, an inner ring 23, and a plurality of rolling elements that are arranged to freely roll in the circumferential direction between the outer ring 21 and the inner ring 23. The ball bearing device includes a certain ball 25, a shield plate 27 that is an annular sealing device mounted on the outer ring 21 so as to sandwich the ball 25, and a cage 29.

  An outer ring raceway surface 21 a that defines an outer ring raceway groove of the ball 25 is formed on the inner circumferential surface of the outer ring 21, and an inner ring raceway surface 23 a that defines an inner ring raceway groove of the ball 25 is also formed on the outer circumferential surface of the inner ring 23. ing. Between the outer ring raceway surface 21a and the inner ring raceway surface 23a, a plurality of balls 25 that are rotatably held by a cage 29 are disposed. The shield plates 27 arranged on both sides of the ball 25 prevent the grease 31 enclosed in the rolling bearing device 100 from leaking to the outside of the rolling bearing device 100.

  Grease 31 is a base oil made of mineral oil or synthetic oil (diester oil, polyvalent ester oil, synthetic hydrocarbon oil, silicone oil, fluorine oil, etc.) and fluorine-based thickening which is a kind of heat-resistant organic thickener. And a semi-solid lubricant to which various additives are added as required.

  On the outer peripheral surface of the outer ring 21, two O-ring grooves 21 b that are spaced apart in the axial direction at substantially the same interval as the width (diameter) of the balls 25 are formed. Each O-ring groove 21b is fitted with an O-ring 33 made of a fluorine-based rubber, and a part of the O-ring groove 21b projects from the outer peripheral surface of the outer ring 21 as a crushing allowance d. The hardness of the O-ring 33 is Hs70, and the crushing allowance d is 20% to 40% of the wire diameter D of the O-ring 33.

  Such a rolling bearing device 100 is inserted into a housing hole 35 a formed in the housing 35 and attached to the housing 35. The fitting between the housing hole 35a and the outer ring 21 is a snug fit or a gap fit, and the two O-rings 33 having a hardness of Hs70 mounted in the O-ring groove 21b of the outer ring 21 are connected to the O-ring 33. The crushing allowance d of 20% to 40% of the diameter D is squeezed into the housing hole 35a.

  Next, the operation of this embodiment will be described. With the operation of a device in which the rolling bearing device 100 is incorporated, such as a dry vacuum pump, radial vibrations act on the rolling bearing device 100, but the radial vibration behavior is two O-rings 33. It is attenuated by the elastic action. As a result, the rotation of the outer ring 21, that is, the occurrence of creep is prevented and fretting is also prevented. Further, a thrust load acts on the rolling bearing device 100 due to the thermal expansion of the shaft and the operation of the equipment. The thrust load can also be absorbed by the elastic action of the two O-rings 33, and the rolling load due to the abnormal thrust load can be absorbed. Sticking is also prevented.

  Here, the reason why the hardness of the O-ring 33 is Hs70 and the crushing amount d is 20% to 40% of the wire diameter D of the O-ring 33 will be described. If the hardness of the O-ring 33 is significantly larger than Hs70, the elastic force of the O-ring 33 is insufficient and the vibrational vibration and thrust load in the radial direction cannot be absorbed efficiently, and the hardness of the O-ring 33 is significantly larger than Hs70. This is because if it is too small, the fixing force with respect to the housing 35 is insufficient, which causes the generation of creep. Further, as shown in FIG. 2, there is a correlation between the crushing allowance d and the creep resistance P, and between the crushing allowance d and the rubber life LT, and the creep resistance P is a large value of the crushing allowance d. It increases in proportion to the height. On the other hand, the rubber life LT tends to be shortened in inverse proportion to the crushing allowance d.

  The crushing allowance d is set to 20% to 40% of the wire diameter D of the O-ring 33. When the hardness of the O-ring 33 is about Hs70, the necessary creep resistance P when the crushing allowance d is less than 20%. If the crushing allowance d is larger than 40%, the rubber life LT of the O-ring 33 (the time until the O-ring 33 deteriorates to a predetermined hardness is reached, and the deterioration of the O-ring 33 in the no-load state occurs. This is because the usable time is not practically usable because it is approximately 80% or less. Accordingly, an appropriate range of 20% to 40% of the wire diameter D of the O-ring 33 is set as the crushing allowance d that satisfies both the creep resistance P and the rubber life LT.

  Since the O-ring 33 is made of fluorine-based rubber, the O-ring 33 will not deteriorate even if the O-ring 33 is exposed to vacuum or reactive gas. Therefore, even if the rolling bearing device 100 is used in a dry vacuum pump or the like, it can sufficiently withstand severe conditions and exhibit stable performance for a long period of time. Further, since the grease 31 contains a fluorine-based thickener, the grease component from the grease 31 is hardly evaporated even when the rolling bearing device 100 is exposed to a vacuum, and the environment caused by the deterioration of the grease 31 or the evaporation of the grease component. Contamination is prevented.

  Also, the number of the O-ring grooves 21b is two and the distance between them is substantially the same as the width (diameter) of the balls 25. The reason why three or more O-ring grooves 21b are formed within the width of the outer ring 21 is physical. In addition, if only one O-ring groove 21b is used, it is difficult to obtain the necessary creep resistance P with only one O-ring 33, and it is difficult to extend the life of the O-ring 33. . By providing two O-ring grooves 21b spaced apart in the axial direction at substantially the same interval as the width of the balls 25, the thickness of the outer ring 21 is ensured and sufficient strength is ensured, and the outer ring 21, that is, the rolling bearing device 100 is secured. Is stably held in the housing hole 35a. Needless to say, it is more preferable that the interval between the O-ring grooves 21b is equal to or greater than the width of the outer ring raceway groove where the thickness of the outer ring 21 is reduced, in other words, equal to or greater than the width of the outer ring raceway surface 21a.

  According to the rolling bearing device 100, two O-ring grooves 21b formed on the outer peripheral surface of the outer ring 21 and spaced apart in the axial direction at substantially the same interval as the width of the rolling element 25 are mounted in the O-ring grooves 21b. In addition, the rolling bearing device 100 is press-fitted into the housing 35 with the O-ring 33 being crushed in the radial direction. Thereby, the radial vibration motion acting on the rolling bearing device 100 is attenuated, and the occurrence of creep and fretting is prevented. Further, since the O-ring 33 is made of a fluorine-based material, the O-ring 33 does not deteriorate even when exposed to a vacuum. Further, the O-ring 33 made of a fluorine-based material does not react with the reactive gas, and even if the rolling bearing device 100 is used for a vacuum pump that sucks the reactive gas, the O-ring 33 is not deteriorated and is stable. Sealed. In addition, since the two O-ring grooves 21b are formed to be spaced apart in the axial direction at substantially the same interval as the width of the rolling element 25, the thickness of the outer ring 21 is significantly reduced by providing the O-ring grooves 21b. Therefore, sufficient strength is ensured.

  Further, according to the rolling bearing device 100, the grease 31 enclosed in the rolling bearing device 100 contains a fluorinated thickener, so that even if the rolling bearing device 100 is exposed to vacuum by being used in a vacuum pump. The grease component is hardly evaporated from the grease 31, and the grease 31 is prevented from being deteriorated or contaminated due to the evaporation of the grease component.

  Furthermore, according to the rolling bearing device 100, the O-ring 33 has a hardness of Hs70, and the crushing amount d is 20% to 40% of the wire diameter D of the O-ring 33. The outer ring 21 is held by the housing 35 with a force larger than P, thereby preventing the occurrence of creep. Therefore, the life of the O-ring 33 can be extended.

  Therefore, the rolling bearing device 100 can be used stably because the performance does not deteriorate for a long time even under severe use conditions such as support of the screw shaft of the dry vacuum pump. Therefore, the life of the rolling bearing device 100 can be extended, and the reliability of the device in which the rolling bearing device 100 is incorporated can be improved.

(Second Embodiment)
Next, a second embodiment of the rolling bearing device (rolling bearing device 200) will be described with reference to FIG. FIG. 3 is a longitudinal sectional view of the upper half of the rolling bearing device according to the second embodiment of the present invention.

  As shown in FIG. 3, in the rolling bearing device 200, the radial thickness t1 of the outer ring 51 is formed thicker than the radial thickness t2 of the inner ring 23. Otherwise, the rolling bearing device 200 is the first embodiment (rolling). The structure is the same as that of the bearing device 100). In addition, the same code | symbol or an equivalent code | symbol is attached | subjected to the same part as the rolling bearing apparatus 100 of 1st Embodiment of this invention, and description is simplified or abbreviate | omitted.

  As shown in FIG. 3, in the rolling bearing device 200, since the radial thickness t1 of the outer ring 51 is formed thicker than the radial thickness t2 of the inner ring 23, the outer ring 51 has high rigidity. Therefore, the creep damping effect is further enhanced, and the occurrence of creep and fretting is reliably prevented. Since other operations and effects of the rolling bearing device 200 can be easily inferred from the above description according to the first embodiment, the description is omitted.

  According to the rolling bearing device 200, the radial thickness t1 of the outer ring 51 is formed thicker than the radial thickness t2 of the inner ring 23, so that the rigidity is high and a higher creep damping effect is obtained. Further, the occurrence of fretting is surely prevented. This also extends the life of the rolling bearing device 200 and improves the reliability of equipment such as a dry vacuum pump in which the rolling bearing device 200 is incorporated.

  In addition, this invention is not limited to embodiment mentioned above, A deformation | transformation, improvement, etc. are possible suitably. In addition, the material, shape, dimension, numerical value, form, number, location, and the like of each component in the above-described embodiment are arbitrary and are not limited as long as the present invention can be achieved.

  In the first embodiment and the second embodiment described above, the ball bearing device is adopted as the rolling bearing device. However, the present invention is not limited to this, and the present invention is also applicable to other types of rolling bearings such as a roller bearing. Can produce the same effect.

It is a longitudinal cross-sectional view of the upper half part of the rolling bearing apparatus which is 1st Embodiment of this invention. It is a graph which shows the relationship between the crushing allowance of O-ring, creep resistance, and rubber lifetime. It is a longitudinal cross-sectional view of the upper half part of the rolling bearing apparatus which is 2nd Embodiment of this invention. It is a principal part longitudinal cross-sectional view of the conventional rolling bearing apparatus.

Explanation of symbols

100, 200 Rolling bearing device 21, 51 Outer ring 21a, 51a Outer ring raceway surface 21b, 51b O-ring groove 23 Inner ring 23a Inner ring raceway surface 25 Ball (rolling element)
27 Shield plate (sealing device)
31 Grease 33 O-ring d O-ring crushing allowance D O-ring wire diameter

Claims (2)

An inner ring having an outer peripheral surface on which an inner ring raceway surface is formed;
An outer ring having an inner peripheral surface on which an outer ring raceway surface is formed;
A plurality of rolling elements arranged to be freely rollable in the circumferential direction between the inner ring raceway surface and the outer ring raceway surface;
A pair of annular sealing devices attached to one of the inner ring and the outer ring so as to sandwich the rolling element;
Two O-ring grooves formed on the outer circumferential surface of the outer ring and spaced apart in the axial direction at substantially the same interval as the width of the rolling elements;
Fluorine rubber O-rings mounted in the O-ring grooves,
A rolling bearing device comprising:
A rolling bearing device in which grease containing a fluorinated thickener is enclosed.   The O-ring has a hardness of Hs70, and a crushing amount of the O-ring that is crushed when the rolling bearing device is mounted on a housing is 20% to 40% of a wire diameter of the O-ring. The rolling bearing device according to claim 1.

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