JP2020528524A - Rolling bearings with lubricant - Google Patents

Abstract

The present invention is a rolling bearing (1) including an inner race (2) and an outer race (3) formed of a race material. The inner race (2) is on the outer peripheral surface, and the outer race (3) is on the inner circumference. Each surface has one orbit (4,5) for guiding the rolling element (6), and the rolling element (6) rolls on each orbit (4,5) and is in space. A lubricant (7) is arranged between the inner race (2) and the outer race (3), and the lubricant (7) comes into contact with at least the inner race (2) and / or the outer race (3). With respect to rolling bearings (1), wherein the race material contains at least alloy components of iron, carbon, chromium, molybdenum and vanadium. According to the present invention, the weight ratio of chromium to molybdenum to vanadium is 1: minimum 0.8 to maximum 1.5 to minimum 0.5 to maximum 1.3.

Description

The present invention lubricates the inner race, the outer race, a plurality of rolling elements spatially arranged between the inner race and the outer race, and the rolling contact portion between these rolling elements and the respective bearing races. With respect to rolling bearings with a lubricant for cooling.

In particular, one of the important failure mechanisms of rolling bearings that support shafts that rotate at high speed is the short life of the lubricant. Insufficient lubrication at the rolling contacts between the rolling elements and their respective bearing races is caused by a tribological overload, especially when combined with high operating temperatures. The mechanism that promotes under-lubrication is, for example, a high spin / roll ratio (Bohr-Roll-Verhaeltnisse) that increases the slip difference between the rolling elements and their respective bearing races, in particular. In particular, this unfavorably changes the viscosity of the lubricant. Further, deterioration of the lubricant leads to further hardening of the lubricant. Since the lubricant in the rolling bearing is usually pushed away by the rolling element set to a region where it does not collide in some cases, the tendency of the base oil to be released from the lubricant to the rolling contact portion is reduced when the lubricant is cured. This results in insufficient lubrication due to oil release. Often, both underlubrication factors occur at the same time, usually leading to an increased sudden breakdown process of the lubricant or a malfunction of the rolling bearing.

The high-speed rotation is a rotation speed exceeding 1 million rotations per minute, which corresponds to n * dm, where n is a rotation speed and dm is an average bearing diameter. For example, high speed rotation is understood to be 10,000 revolutions per minute with an average bearing diameter of 100 mm.

An object of the present invention is to further improve the rolling bearing, and particularly to extend the period of use of the lubricant contained in the rolling bearing.

This problem is solved by a rolling bearing having the characteristics according to claim 1. Suitable or advantageous embodiments of the present invention will be apparent from the dependent claims, the description below and the accompanying drawings.

The rolling bearing according to the present invention includes an inner race and an outer race formed of a race material, the inner race has an outer race surface, the outer race has an inner peripheral surface, and one track for guiding a rolling element. The rolling elements roll on their respective orbits, and the lubricant is spatially placed between the inner race and the outer race, and the lubricant comes into contact with at least the inner race and / or the outer race. The lace material contains at least an alloy component of iron, carbon, chromium, molybdenum and vanadium, with a chromium to molybdenum to vanadium weight ratio ratio of 1: minimum 0.8 to maximum 1.5 to minimum 0. .5-Maximum 1.3. In particular, the weight ratio of molybdenum to vanadium is a minimum of 1 to a maximum of 3.

In other words, the weight ratio is Cr: Mo: V = 1: 0.8 to 1.5: 0.5 to 1.3. Further, the weight ratio is Mo: V = 1: 3. Therefore, the weight ratio of chromium to molybdenum to vanadium causes the lubricant to oxidize so that the oil flow from the lubricant to the track provided in the inner race or outer race is controlled to lubricate the rolling contacts. By adjusting, the period of use of the lubricant in rolling bearings, especially spindle bearings rotating at high speed, can be extended.

Oxidation is understood to be an increase in the fluidity of the lubricant or the base oil contained in the lubricant. Oxidation of lubricants is usually an undesirable process. This is because oxidation of the lubricant leads to faster exudation of the lubricant. Exudation is understood to be the outflow of base oil from the lubricant. The deliberate blending of chromium, vanadium and molybdenum in the lace material controls the oxidation of the lubricant. In this case, hardening is prevented and at the same time slow and intentional oozing of the lubricant is achieved. For this, the lubricant comes into contact with the lace material.

Preferably, the weight ratio of chromium to molybdenum to vanadium is 1: minimum 1.1 to maximum 1.3 to minimum 0.65 to maximum 0.85. In other words, the weight ratio is Cr: Mo: V = 1: 1.1 to 1.3: 0.65 to 0.85. This preferred weight ratio of chromium to molybdenum to vanadium further extends the life of the lubricant.

Preferably, the weight ratio of molybdenum to vanadium is at least 1.25 to at most 1.8. Therefore, the weight ratio is Mo: V = 1.25: 1.8. This preferred weight ratio of molybdenum to vanadium further extends the life of the lubricant.

More preferably, the rolling elements are made of ceramic or lace material. The combination of inner laces and outer laces made of the lace material according to the present invention with a rolling element made of a ceramic material reduces the demand for lubricants. This is because metal-ceramic pairs form smaller contact surfaces under the same geometry and load than metal-metal pairs. In addition, adhesive or abrasive wear processes are blocked by metal-ceramic material pairs.

The present invention includes the technical teaching that a lubricant contains a polyalphaolefin or ester oil as a base oil. Preferably, the lubricant comprises polyarylurea, lithium complex soap, or barium complex soap as the thickener.

According to a preferred embodiment, the lubricant is a spindle bearing grease according to the standard KEHC3K-50 according to DIN 51825. The operating temperature range is −50 ° C. to 120 ° C. according to DIN 51825. The base oil consistency at 40 ° C. is 22 mm ² / s according to DIN 51562-1. Further, the miscibility (1/10 mm) according to DIN ISO 2137 is 220 to 250. The NLGI class according to DIN 51818 is 3. The drop point according to DIN ISO 2176 is 250 ° C. or higher.

According to another preferred embodiment, the lubricant is spindle bearing grease to standard KPHC2 / 3K-40 according to DIN 51825. The operating temperature range is −40 ° C. to 120 ° C. according to DIN 51825. The base oil consistency at 40 ° C. is 25 mm ² / s according to DIN 51562-1. Further, the miscibility (1/10 mm) according to DIN ISO 2137 is 250 to 265. The NLGI class according to DIN 51818 is 2 or 3. The drop point according to DIN ISO 2176 is 220 ° C. or higher.

Another means of improving the present invention will be described in detail below with reference to the accompanying drawings, along with a description of preferred embodiments of the present invention.

It is a schematic perspective view of the rolling bearing which concerns on this invention. It is a schematic partial sectional view of the bearing assembly provided with the rolling bearing and a shaft shown in FIG.

According to FIG. 1, the rolling bearing 1 according to the present invention for a machine tool (not shown) is a rolling bearing 1 arranged between an inner race 2 and an outer race 3 and between the inner race 2 and the outer race 3 in the radial direction. It contains a ball as a moving body 6. The rolling element 6 is guided by the cage 8. The rolling bearing 1 is formed as a deep groove ball bearing.

In FIG. 2, the rolling bearing 1 shown in FIG. 1 supports the shaft 9. The shaft 9 is formed here as a spindle shaft of a machine tool. The inner race 2 has an orbit 4 for guiding the rolling element 6 on the outer peripheral surface. Further, the outer race 3 also has a track 5 on the inner peripheral surface for guiding the rolling element 6. The rolling element 6 rolls on the respective trajectories 4 and 5 between the inner race 2 and the outer race 3, and the rolling element 6 is formed of a ceramic material. Further, spatially lubricate and cool the rolling contact portion between the inner race 2 and the rolling element 6 and the rolling contact portion between the outer race 3 and the rolling element 6 between the inner race 2 and the outer race 3. Lubricant 7 for this purpose is arranged. The lubricant 7 comes into contact with the inner race 2, the outer race 3, and the rolling element 6.

The inner race 2 and the outer race 3 are formed of lace material. The lace material contains at least alloy constituents of iron, carbon, chromium, molybdenum and vanadium. The weight ratio of chromium to molybdenum to vanadium is 1: minimum 0.8 to maximum 1.5 to minimum 0.5 to maximum 1.3. The weight ratio of molybdenum to vanadium is a minimum of 1 to a maximum of 3. The lubricant 7 contains a polyalphaolefin as a base oil and a polyarylurea as a thickener. The deliberate blending of the weight proportions of chromium, vanadium and molybdenum in the race material controls the oxidation of the lubricant 7 and prevents hardening while at the same time intentionally flowing the base oil from the lubricant 7. It will be realized. As a result, the period of use of the lubricant 7 in the rolling bearing 1 is extended.

1 Rolling bearing 2 Inner race 3 Outer race 4 Track 5 Track 6 Ball 7 Lubricant 8 Cage 9 Shaft

Claims (8)

A rolling bearing (1) including an inner race (2) and an outer race (3) formed of a race material, wherein the inner race (2) is on the outer peripheral surface and the outer race (3) is on the inner peripheral surface. Each of the rolling elements (6) has one orbit (4,5) for guiding the rolling elements (6), and the rolling elements (6) roll on the respective orbits (4,5) and are in space. A lubricant (7) is arranged between the inner race (2) and the outer race (3), and the lubricant (7) is at least the inner race (2) and / or the outer race. In the rolling bearing (1), which is in contact with (3) and the race material contains at least alloy constituents of iron, carbon, chromium, molybdenum and vanadium.
Rolling bearings (1), characterized in that the weight ratio of chromium to molybdenum to vanadium is 1: minimum 0.8 to maximum 1.5 to minimum 0.5 to maximum 1.3. The rolling bearing (1) according to claim 1, wherein the ratio of the weight ratio of molybdenum to vanadium is a minimum of 1 to a maximum of 3. The rolling bearing (1) according to claim 1 or 2, wherein the ratio of the weight ratio of chromium to molybdenum to vanadium 1 is 1: minimum 1.1 to maximum 1.3 to minimum 0.65 to maximum 0.85. The rolling bearing (1) according to any one of claims 1 to 3, wherein the ratio of the weight ratio of molybdenum to vanadium is at least 1.25 to at most 1.8. The rolling bearing (1) according to any one of claims 1 to 4, wherein the rolling element (6) is formed of a ceramic material or the race material. The rolling bearing (1) according to any one of claims 1 to 5, wherein the lubricant (7) contains a polyalphaolefin or an ester oil as a base oil. The rolling bearing (1) according to any one of claims 1 to 6, wherein the lubricant (7) contains polyarylurea, lithium complex soap, or barium complex soap as a thickener. Use of the rolling bearing (1) according to any one of claims 1 to 7, for bearing the spindle shaft, bearing the compressor shaft, or bearing the rotor shaft.

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