JPH0645119U - Lubricator for high-speed rotating bearing - Google Patents

Abstract

(57) [Summary] [Purpose] To improve cooling capacity and reduce shaft torque loss. [Structure] An outer ring spacer 11 in contact with an end surface of an outer ring 4 has a first injection hole 12 for supplying a lubricant L toward an annular space 8.
And a second injection hole 13 for supplying the lubricant L toward the space between the outer diameter of the inner ring 2 and the inner diameter of the cage 6. The first and second injection holes 12 and 13 communicate with the oil supply passage 3a of the housing 3 via the nozzles 11a and 11b, respectively. The lubricant L is a water-soluble lubricant.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a lubricating device for a bearing used under high-speed rotation, such as a bearing that rotatably supports a main shaft of a machine tool.

[0002]

[Prior art]

 For example, the speeding up of machine tool spindles centering on machining centers has been extremely significant. The reason is, of course, that we are trying to improve machining accuracy and productivity by increasing the cutting speed by increasing the spindle speed.

Rolling bearings, sliding bearings, hydrostatic bearings, magnetic bearings, and the like can be cited as the types of bearings used for machine tool spindles. Rolling bearings have high rigidity and load capacity and are easy to handle. It is the most commonly used bearing type for machine tool spindles because it has been standardized and stable bearings are available at a relatively low price.

By the way, if the rolling bearing is used carelessly under high speed rotation, the temperature of the bearing and the preload may increase. Therefore, such a high-speed rotary bearing requires particularly sufficient lubrication.

Conventionally, oil mist lubrication method, oil air lubrication method, nozzle jet lubrication method, underlace lubrication method and the like have been known as lubrication methods for high speed rotating bearings. Of these lubrication methods, representative nozzle jet lubrication methods and underlace lubrication methods will be briefly described. First, in the nozzle jet lubrication method, as shown in FIG. 3, the lubricant L ′ is supplied from the nozzle 33 toward the space between the outer diameter of the inner ring 31 and the inner diameter of the retainer 32. It is characterized in that the lubricant L ′ can be stably supplied. Next, the under-race lubrication method, as shown in FIG. 4, supplies the lubricant L ′ to the through hole 42 that runs axially below the raceway surface of the inner ring 41 to cool the inner ring 41, and at the same time, in the radial direction. The lubricant L ′ is supplied from the passage 43 into the bearing to lubricate the inside of the bearing, and in particular, it is characterized in that the temperature rise of the inner ring 41 can be effectively suppressed.

[0006]

[Problems to be solved by the device]

 Needless to say, the role of the lubricant is to reduce friction loss in the bearing and suppress heat generation and friction, but especially in high-speed rotary bearings, the amount of heat generated in the bearing is absorbed and discharged to the outside of the bearing. However, suppressing the bearing temperature rise also plays an important role. Therefore, a lubricant for high-speed rotating bearings must have excellent properties as a heat exchange medium in addition to its properties such as viscosity and oxidation stability. The specific heats of typical lubricants that are commonly used are shown below (unit: Btu / lb / Fat 100 ° F).

Silicone oil 0.35

Diester oil 0.43

Steam turbine oil 0.45

Water 1.00

From the above, it can be seen that the generally used lubricant (lubricating oil) is inferior to water in heat exchange capacity by about 35 to 50%. In the past, it can be said that this poor heat exchange capacity has been dealt with by increasing the supply amount of lubricant.

However, in recent years, in the field of machine tools and the like, higher speed tends to be further promoted, and it is expected that the bearing temperature will rapidly increase as the bearing rotation speed further increases. In order to properly cope with such a tendency, there are limits in terms of capacity and cost by means such as simply selecting a lubricating system and increasing the amount of lubricant supplied.

Further, an increase in shaft torque loss due to an increase in agitating resistance of the lubricant during rotation of the bearing is also a concern. Axial torque loss is especially problematic in nozzle jet lubrication.

Therefore, an object of the present invention is to provide, as a lubricating device for a high-speed rotary bearing, a lubricating device having a better cooling capacity and less torque loss.

[0015]

[Means for Solving the Problems]

 The lubricating device for a high-speed rotary bearing of the present invention uses a water-soluble lubricant as a lubricant.

[0016]

[Action]

 The water-soluble lubricant has a larger specific heat than a commonly used lubricant (lubricating oil) and has a good heat exchange efficiency, so that a larger amount of heat can be discharged to the outside of the bearing. In addition, since the viscosity is low, the stirring resistance of the lubricant during rotation of the bearing is small.

[0017]

【Example】

 Embodiments of the present invention will be described below with reference to the drawings.

The embodiment shown in FIG. 1 is an application of the present invention to a lubrication device for angular ball bearings. The angular contact ball bearing has an inner ring 2 fixed to a shaft 1, an outer ring 4 fixed to a housing 3, a plurality of balls 5 rotatably interposed between the inner and outer rings 2 and 4, and a ball 5. It is composed of a cage 6 which holds the circles at equal intervals.

One end of the inner ring 2 extends in the axial direction to form a scoop 7. An inner side of the scoop 7 is an annular space 8, and the annular space 8 is communicated with one opening 9a of a plurality of through holes 9 running axially below the raceway surface 2a of the inner ring 2. Further, the through hole 9 and the raceway surface 2 a of the inner ring 2 communicate with each other via a radial passage 10.

The outer ring spacer 11 in contact with the end surface of the outer ring 4 is provided between the first injection hole 12 that supplies the lubricant L toward the annular space 8 and the outer diameter of the inner ring 2 and the inner diameter of the cage 6. Second injection hole 13 for supplying the lubricant L toward the space. The first and second injection holes 12 and 13 communicate with the oil supply passage 3a of the housing 3 via the nozzles 11a and 11b, respectively.

The lubricant L is a water-soluble lubricant (polyethylene glycol-based water-soluble oil such as Nisseki Precise Fluid 2001). The water-soluble lubricant has a larger specific heat (about 1.0) than the commonly used lubricant (lubricating oil) and has a good heat exchange efficiency. Further, it has a lower viscosity (kinematic viscosity 1.99 cst) than the lubricating oil.

The lubricant L supplied from the first injection hole 12 flows into the through hole 9 via the annular space 8 and cools the inner ring 2. Further, a part of the lubricant L that has flowed into the through hole 9 is supplied to the raceway surface 2a of the inner ring 2 through the radial passage 10 and mainly lubricates the raceway surface 2a. The lubricant L supplied from the second injection hole 13 flows into the space between the outer diameter of the inner ring 2 and the inner diameter of the retainer 6, and then moves to the outer diameter side by the centrifugal force caused by the rotation of the bearing. The inside is lubricated and the outer ring 4 is cooled. As described above, the lubricating device of this embodiment is a combination of the nozzle jet lubrication and the underless lubrication described above.

In the embodiment shown in FIG. 2, an annular groove 15 is formed on the end surface of the inner ring 2 instead of the scoop 7. In this embodiment, the space surrounded by the wall surface of the annular groove 15 becomes the annular space 8 for introducing the lubricant L supplied from the first injection hole 12 into the through hole 9.

In the embodiment described above, one oil supply path is branched into two paths by the nozzles 11a and 11b, but when using an oil supply unit capable of adjusting the oil temperature and the oil amount, etc. Alternatively, the lubricant L may be supplied to the first and second injection holes 12 and 13 from independent oil supply paths, respectively. The oil temperature and oil of the lubricant L supplied to the first and second injection holes 12 and 13 according to the temperature difference between the inner and outer rings 2 and 4 when the bearings rotate, the lubrication state on the raceways 2a and 4a, and the like. By adjusting the amount individually, a more optimal cooling / lubrication effect can be achieved.

Further, the present invention can be similarly applied to other lubrication methods such as an air-oil lubrication method, and is not limited to the illustrated angular ball bearings but can be widely applied to rolling bearings in general. "

[0026]

[Effect of device]

 As described above, according to the present invention, since the water-soluble lubricant is used in the lubricating device for the high-speed rotary bearing, the amount of heat generated in the bearing can be more efficiently discharged to the outside of the bearing. Therefore, the bearing temperature rise can be suppressed more effectively. Further, since the water-soluble lubricant has a low viscosity, the stirring resistance during rotation of the bearing is small. Therefore, the shaft torque loss can be reduced more than ever before.

[Brief description of drawings]

FIG. 1 is a cross-sectional view (FIG. A) showing an embodiment of the present invention, and a view on arrow A direction in FIG.

FIG. 2 is a sectional view showing another embodiment of the present invention.

FIG. 3 is a cross-sectional view showing a conventional lubricating device.

FIG. 4 is a sectional view showing a conventional lubricating device.

[Explanation of symbols]

 2 Inner ring 9 Through hole 12 First injection hole 13 Second injection hole L Lubricant

Claims (1)

[Scope of utility model registration request] 1. A high-speed bearing, wherein a lubricant is forcibly supplied to a bearing used for high-speed rotation to lubricate and cool the bearing, wherein a water-soluble lubricant is used as the lubricant. Lubricating device for rotary bearings.