JPH1096426A - Roller bearing cage used at high speed and its manufacturing method - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To ensure sufficient lubricity and improve durability even when sufficient lubricating oil cannot be supplied at high speed. SOLUTION: A retainer 7 is made of fiber reinforced polyimide resin. By barrel processing, on the corner existing on the surface,
Form a minute curved surface. Also, the inside is impregnated with lubricating oil.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of a cage incorporated in a rolling bearing for supporting a high-speed rotating portion such as a main shaft of a machine tool used for gas turbine, turbocharger, or oil-air lubrication.

[0002]

2. Description of the Related Art Conventionally, an angular type ball bearing 1 as shown in FIG. 1 has been widely used to support a high-speed rotating portion such as a main shaft of a machine tool. In this ball bearing 1, an inner ring 3 having an inner ring raceway 2 on the outer peripheral surface and an outer ring 5 having an outer ring raceway 4 on the inner peripheral surface are concentrically arranged. Balls 6 are provided so as to freely roll. The plurality of balls 6, 6 are rotatably held by a holder 7 as shown in FIG.

Conventionally, such a retainer 7 is integrally formed by cutting a cylindrical material made of brass or extruded synthetic resin or by injection molding synthetic resin. I have. Further, although the shape of the retainer itself is slightly different, the retainer may be formed by pressing a metal plate. In any case, the retainer 7 is cylindrical in its entirety, and has cylindrical pockets 8, 8 formed at regular intervals in the circumferential direction. The balls 6, 6 are rollably held in the pockets 8, 8, respectively.

[0004] It is necessary to prevent such a cage 7 from being displaced in the radial direction due to rotation, and to prevent the cage 7 from causing the vibration of the rolling bearing. A cage 7 for a rolling bearing such as the ball bearing 1 used for supporting a portion rotating at a high speed generally has an outer ring guide for bringing the outer peripheral surface of the retainer 7 close to the inner peripheral surface of the outer ring 5. In most cases, the displacement in the radial direction is prevented by a method or an inner ring guide method in which the inner peripheral surface of the retainer 7 and the outer peripheral surface of the inner ring 3 are brought close to each other. Also, the shape and material of the cage 7 incorporated in such a rolling bearing are selected and used according to the intended use. Further, even in such lubrication of rolling bearings, a lubrication system according to the application is adopted.

[0005] However, concerning the lubrication, d _m n lubrication of rolling bearings are used in more than 800,000 high-speed rotation region {pitch circle diameter d _m (mm) and the product of the rotational speed n (rpm)} Is
It is difficult to use grease because oil film formation becomes unstable and causes seizure. For this reason, a lubrication method such as oil mist, oil air, jet lubrication, or under-race lubrication is generally employed for lubricating the rolling bearing used in the high-speed rotation region as described above. By adopting such a lubrication system, the rolling bearing can rotate smoothly,
In order to prevent damage such as seizure, whether or not an oil film is formed depending on the properties and amount of the lubricating oil, the degree of heat generation due to rotational resistance, and whether or not a certain amount of lubricating oil is supplied into the bearing Is a problem. As the operating speed of the rolling bearing increases, it becomes more difficult to supply a sufficient amount of lubricating oil to the inside of the rolling bearing, and the lubrication state tends to be a minute amount of oil lubrication. Therefore, as the operation speed increases, wear and seizure of the rolling bearing become more problematic.

On the other hand, the cage 7 incorporated in the rolling bearing for high-speed rotation needs to have sufficient rigidity in order to prevent breakage due to centrifugal force acting during operation. Also, heat resistance is required to prevent thermal deformation due to frictional heat generated during high-speed rotation. In view of such circumstances, JP-A-3-13-1
No. 88127 discloses that by forming a cage with a thermoplastic polyimide resin, the cage has heat resistance, oil resistance,
The invention which gives chemical resistance and injection moldability is described. Furthermore, Japanese Utility Model Application Laid-Open No. 4-95125 describes an invention in which a cage of a rolling bearing for a turbocharger is made of a thermoplastic polyimide resin, and the performance of the rolling bearing incorporating the cage is improved.

[0007]

However, the rolling bearing cages described in the above publications have heat resistance, oil resistance, chemical resistance, and injection moldability, but ensure lubricity at high speeds. Things are difficult. Therefore, when the rolling bearing is rotating at a high speed, it is difficult to supply an appropriate amount of lubricating oil to the inside of the rolling bearing even if a forced lubrication method such as jet lubrication is adopted. In addition, considering that the rotational torque of the rolling bearing is suppressed to a small value and the high rotational speed is maintained, it is difficult to supply a large amount of lubricating oil, and the lubrication state inside the rolling bearing is often minutely lubricated. As a result, wear and seizure are likely to occur due to poor lubrication, and a rolling bearing having sufficient durability may not always be provided.

In view of such circumstances, the present invention maintains good lubricating properties over a long period of time, and achieves excellent lubrication under a small amount of lubrication.
The present invention is intended to realize a high-speed rolling bearing capable of maintaining stable rotation accuracy and obtaining good durability even when rotating at a high speed of about 0 to 150,000 rpm.

[0009]

According to the present invention, there is provided a cage for rolling bearings used at high speed and a method for manufacturing the same, wherein the cage for rolling bearings used at high speed according to claim 1 is made of fiber reinforced polyimide resin. A chamfered minute curved surface is formed by barrel processing on a corner portion existing on the surface, and the inside is impregnated with lubricating oil.

According to a second aspect of the present invention, there is provided a method for manufacturing a cage for a rolling bearing used at a high speed, wherein a plurality of pockets are formed in a ring shape and entirely in the circumferential direction by a fiber reinforced polyimide resin having thermoplasticity. After forming the retainer element having, by subjecting the retainer element to barrel processing, a minute curved surface is formed at a corner present on the surface of the retainer element,
Then, by immersing the cage element in lubricating oil,
The retainer element is impregnated with lubricating oil. When the cage element is immersed in the lubricating oil, the lubricating oil is preferably heated to a glass transition point _Tg or lower of the fiber-reinforced polyimide resin (the amorphous part flows). Keep it. Further, if necessary, the immersion operation is performed while pressurizing the lubricating oil. The reason why the lubricating oil is heated and pressurized in this way is to increase the amount of the lubricating oil impregnated in the cage element.

[0011]

The fiber reinforced thermoplastic polyimide resin (hereinafter referred to as "fiber reinforced thermoplastic polyimide resin") used in the present invention has oil resistance, heat resistance, and chemical resistance, and therefore lubricates rolling bearings. It does not swell or deform due to the lubricating oil. Also, there is no deformation due to heat generated by high-speed rotation. Furthermore, even when used under conditions exposed to chemicals, they are not affected by the chemicals.

Also, a corner present on the surface of the cage, ie,
The corners that exist in the continuation of the inner and outer peripheral edges of each pocket, the outer peripheral surface and the inner peripheral surface, and the continuation of the inner and outer peripheral edges of the axial end surfaces, have a small amount of barrel processing. Since the curved surface is formed, the rotational resistance can be reduced and the lubricity can be improved. That is, with the above barrel processing,
When forming the retainer element with the fiber-reinforced thermoplastic polyimide resin, burrs generated at the corners are removed, and a minute curved surface having a small radius of curvature is formed at the corners. As a result, the corners and the rolling surface of the rolling element held in the pocket are not strongly rubbed, and the resistance required for the rolling element to rotate in the pocket is reduced. In addition, by making the above-mentioned corner a curved surface, this corner is
The oil film adhered to the rolling surface of the rolling element is less scraped. As a result, the amount of lubricating oil existing between the rolling surface of the rolling element and the outer raceway and the inner raceway is ensured, and the lubricating oil film is formed on the contact portion between the rolling surface and the outer raceway and the inner raceway. Is easy to form. The radius of curvature of the minute curved surface formed at the corner is preferably 0.1 mm or more.

In the above cage, the cage element is immersed in a high-pressure and high-temperature ( _Tg or less) lubricating oil.
Since the lubricating oil is impregnated, when the rolling bearing incorporating the retainer is rotated at high speed, the lubricating oil impregnated in the retainer seeps into the rolling portion of the rolling element. Since such oozing of the lubricating oil is carried out little by little over a long period of time, the lubrication of the rolling bearing incorporating the high-speed rolling bearing retainer of the present invention can be carried out well over a long period of time. It is. In particular, it is possible to suppress a decrease in the surface roughness of the rolling element due to micro seizure or wear, which often occurs when the rolling bearing is operated at a high speed in a minute lubrication state, and excellent durability can be obtained.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In order to manufacture a high-speed rolling bearing cage of the present invention, first, a fiber-reinforced thermoplastic polyimide resin is formed into a desired cage shape to form a cage element. After that, by performing barrel processing on this cage element, the inner peripheral side of the inner side of each pocket, the outer peripheral side of both sides of the opening, the outer peripheral surface and both ends of the inner peripheral surface and the inner and outer peripheral edges of both ends in the axial direction. A chamfered minute curved surface is formed at a corner present in the continuous portion. Thereafter, the cage element is heated to a high temperature ( _Tg or less).
By being immersed in high-pressure lubricating oil, the present invention provides a high-speed rolling bearing retainer for use in the present invention.

As the fiber to be mixed as a reinforcing material into the fiber reinforced thermoplastic polyimide resin, carbon fiber or aramid fiber is preferable. The reason for this is that the retainer, which is the object of the present invention, is required to be lightweight, have high strength, high rigidity and heat resistance in order to be used at high speed and high temperature. It is necessary to use. In order to obtain the desired cage shape by molding the fiber-reinforced thermoplastic polyimide resin, a rod-shaped material obtained by compression molding may be subjected to cutting, or a general in-line screw type injection molding. Injection molding is performed using a molding machine.

In addition, at the corners existing at the continuation of the peripheral edges of the inner and outer diameter openings of each pocket, the outer peripheral surface and the inner peripheral surface, and the inner and outer peripheral edges of the axial end surfaces, The barrel processing for forming the chamfered minute curved surface is performed using a rotary barrel processing machine or a planetary rotary barrel processing machine. That is, the cage element is put into a suitable barrel processing machine selected according to the shape of the cage, etc. together with a suitable medium and a compound also selected according to the shape of the cage, and subjected to barrel processing for a predetermined time.

Further, the kind of the lubricating oil to be impregnated into the barrel-treated cage element is not particularly limited.
In addition to paraffinic mineral oil, naphthenic mineral oil, fluorine oil and silicone oil, ester-based synthetic lubricating oils and the like can be preferably used. In particular, the same type of lubricating oil used for lubricating rolling bearings used at high speed, incorporating the cage of the present invention,
It is suitable as a lubricating oil for impregnating the cage.

The impregnating lubricating oil selected from these is used in an amount of 0.1 to 0.5 part by weight based on 100 parts by weight of the retainer element formed by molding the above fiber-reinforced thermoplastic resin. Impregnate. Although the viscosity of the lubricating oil for impregnation is not particularly limited, the kinematic viscosity at 40 ° C. is 10 to 100 mm ² /
Those in the range of s are preferred. The reason for this is that when a low-viscosity lubricating oil having a kinematic viscosity of less than 10 mm ² / s is used, oil film breakage tends to occur and lubrication failure tends to occur. ^{If a} high-viscosity lubricating oil exceeding ² / s is used, it becomes difficult for the lubricating oil to impregnate into the cage element, and the amount of lubricating oil contained in the cage becomes insufficient.

The operation of impregnating the retainer element made of fiber reinforced thermoplastic polyimide resin with the lubricating oil as described above is preferably carried out by using a heating and pressurizing device such as an autoclave. That is, using such a device, the retainer element is impregnated with the lubricating oil for impregnation while controlling the temperature and pressure of the lubricating oil for impregnation and the processing time for impregnation. Preferred conditions used in impregnating the retainer element made of the fiber-reinforced thermoplastic polyimide resin with the lubricating oil in this manner are as follows. The temperature of the lubricating oil for impregnation is preferably 100 to 150 ° C, more preferably 12 to 150 ° C.
0 to 130 ° C. The reason is that it is preferable to increase the temperature in order to secure the impregnation amount in a short processing time,
Since modifications to the retainer element takes place in the above T _g of the fiber-reinforced thermoplastic polyimide resin, it is because the upper limit is restricted by the T _g. Further, the inside of the device is pressurized in order to make a sufficient amount of lubricating oil in the retainer element, and it is preferable to use nitrogen gas as the pressurizing gas. The reason for this is to prevent the lubricating oil for impregnation from being oxidized and to prevent the lubricating oil from deteriorating. It should be noted that as the pressure at the time of pressurization is higher, more lubricant oil can be impregnated in a shorter time. However, at an extremely high pressure, not only the equipment to be used becomes expensive, but also the amount of nitrogen gas used increases and the cost increases. Therefore, the pressure is regulated to about 15 to 25 kg / cm ^{2 in} terms of cost. Further, the impregnation time is regulated in consideration of the cost to such an extent that a sufficient impregnation amount can be secured in relation to the above-mentioned temperature and pressure. That is, although the amount of impregnation tends to increase as the impregnation time increases, about 5 to 8 hours is appropriate from the viewpoint of cost.

[0020]

Next, an experiment conducted to confirm the effect of the present invention will be described. In order to confirm the effect of the rolling bearing cage used at high speed of the present invention, a cage as a test piece was incorporated into the following two types of angular type ball bearings shown in (1) and (2). A rotation test was performed in which the inner ring was rotated while applying a radial load and a thrust load while the outer ring constituting each ball bearing was fixed. The shape of the cage as the test piece was a so-called hollow cage for an angular ball bearing as shown in FIG. (1) Inner diameter 8 mm, outer diameter 32 mm, width 10 mm (2) Inner diameter 10 mm, outer diameter 32 mm, width 10 mm The test conditions of the rotation test are as follows. Inner ring rotation speed 100,000 rpm Radial load 10 kgf Thrust load 20 kgf Ambient temperature 150-250 ° C Test time 1,000 hours Lubrication conditions Jet lubrication with synthetic lubricating oil (Mobil SHC824)

The evaluation method after the rotation test performed under the above conditions is as follows. Bearing seizure life Fine seizures caused by oil film breakage, i.e., checking for the presence of discoloration, further wear, scratches, etc., were performed by measuring the surface roughness of the balls and observing them with an external microscope. The determination of burn-in was made by performing a rotation test for a predetermined time and then visually confirming a decrease in the ball surface roughness, the presence or absence of band-like discoloration, scratches, cloudiness of the ball (reduction in gloss), and the like. Durability of cage The durability of the cage was determined by measuring the abrasion condition of the inner peripheral surface of the pocket of the cage caused by the oil film breakage by a shape measuring instrument, and judging the presence or absence of the durability by the presence or absence of abnormal wear.

As the test pieces used in the experiments, two kinds of examples belonging to the technical scope of the present invention and two kinds of comparative examples out of the technical scope of the present invention were prepared, that is, four kinds in total. Each test piece was made as follows.

Example 1 A cage element made by injection molding a fiber-reinforced thermoplastic polyimide resin into a shape as shown in FIG. It was loaded together with Compound II and barreled. The operating speed of the barrel processing machine was 150 rpm, and the processing time was 3 hours. By this barrel processing, chamfered minute curved surfaces were formed at the corners of the cage element surface. In the next step, the synthetic lubricating oil (Mobil SHC62
9) was impregnated. This impregnation is performed using an autoclave (pressure-resistant glass TAS-3 type), and the lubricating oil in the autoclave is reduced to 20 kg / cm 2 with nitrogen gas.
² and a 5-hour immersion treatment while heating to 110 ° C. As a result, the cage element was impregnated with 0.12% by weight of the lubricating oil. The cage obtained in this manner was incorporated into the two types of angular type ball bearings described in (1) and (2) above, and a rotation test was performed under the test conditions described above. The results of this experiment are shown in Table 1 and FIG. FIGS. 3A to 3D show the results of measuring the axial cross-sectional shape of the inner peripheral surface of the pocket using a shape measuring instrument after the rotation test. These Table 1 and FIG.
As is clear from the above, the rolling bearing incorporating the high-speed rolling bearing retainer of Example 1 can ensure sufficient lubrication even at high temperatures and high speeds, and has significant seizure and large wear of the balls and the cage. And the durability of the rolling bearing can be improved. During the impregnation, the temperature of the lubricating oil was set to 120
C., the cage element was impregnated with 0.15% by weight of lubricating oil. The cage thus obtained was subjected to a rotation test under the same conditions as in Example 1 above, and almost the same results as in Example 1 were obtained.

[Embodiment 2] A cage element manufactured in the same manner as in the above-described embodiment 1 is subjected to the same barrel processing as in the embodiment 1, and then the same autoclave as in the embodiment 1 is used. A synthetic lubricating oil (Mobil SHC824) was impregnated. During the impregnation, the lubricating oil was heated to 120 ° C., and the lubricating oil was immersed for 5 hours while pressurizing the lubricating oil to 20 kg / cm ² with nitrogen gas. As a result, the retainer was impregnated with 0.15% by weight of lubricating oil. The cage obtained in this manner was incorporated into the two types of angular type ball bearings described in (1) and (2) above, and a rotation test was performed under the test conditions described above. The results of this experiment are shown in Table 1 and FIG.
As is clear from Table 1 and FIG.
Rolling bearings incorporating a cage for rolling bearings used at high speeds can also provide sufficient lubrication even at high temperatures and high speeds, greatly reducing micro seizures and abrasion of balls and cages, and endurance of rolling bearings. Performance can be improved. When the temperature of the lubricating oil was set to 150 ° C. during the impregnation treatment, the retainer element was impregnated with 0.20% by weight of the lubricating oil. The cage thus obtained was subjected to a rotation test under the same conditions as in Example 2 above, and almost the same results as in Example 2 were obtained.

[Comparative Example 1] The two types of angular ball bearings described in the above (1) and (2) were not subjected to barrel processing and impregnation processing on the cage element manufactured in the same manner as in the above-mentioned Example 1. And a rotation test was performed under the test conditions described above. The results of this experiment are shown in Table 1 and FIG. As is clear from Table 1 and FIG. 3 (C), the rolling bearing incorporating the cage of Comparative Example 1 cannot obtain sufficient lubricity at high temperatures and high speeds, resulting in minute seizure and wear of the balls and the cage. And the durability of the rolling bearing cannot be ensured.

[Comparative Example 2] A cage element manufactured in the same manner as in Example 1 described above was subjected to barrel processing to form a minute curved surface at a corner of the surface. The cage element was incorporated into the two types of angular type ball bearings described in (1) and (2) without being impregnated with the lubricating oil, and a rotation test was performed under the test conditions described above. The results of this experiment are shown in Table 1 and FIG. As is clear from Table 1 and FIG.
The rolling bearing incorporating the cage of Comparative Example 2 also cannot obtain sufficient lubrication at high temperatures and high speeds, and significant seizure and wear of the balls and the cage become remarkable, so that the durability of the rolling bearing cannot be ensured.

[0027]

[Table 1]

[0028]

The cage for a rolling bearing used at high speed and the method of manufacturing the same according to the present invention are constructed and operated as described above.
It is possible to maintain good rotational accuracy, reduce pocket wear, secure sufficient durability, and secure seizure resistance to secure sufficient reliability.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing an example of a rolling bearing incorporating a cage to which the present invention is applied.

FIG. 2 is a side view of a cage to which the present invention is applied.

FIG. 3 is an exaggerated diagram showing an axial shape of an inner surface of a pocket of a retainer, showing a result of an experiment performed to confirm an effect of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Ball bearing 2 Inner ring track 3 Inner ring 4 Outer ring track 5 Outer ring 6 Ball 7 Cage 8 Pocket

Claims (2)

[Claims] 1. A high-speed rolling bearing retainer made of fiber reinforced polyimide resin, having a fine curved surface formed by barrel processing at a corner present on the surface, and impregnated with lubricating oil therein. 2. After forming a cage element having a plurality of pockets extending in a circumferential direction in a whole ring shape by using a fiber reinforced polyimide resin having thermoplasticity, barrel processing is performed on the cage element. By forming a minute curved surface at a corner present on the surface of the cage element, and then immersing the cage element in lubricating oil, impregnating the cage element with lubricating oil, rolling at high speed Manufacturing method of bearing cage.