JP2020143753A - Rolling bearing - Google Patents

Abstract

To provide a rolling bearing for an aircraft jet engine of which cooling performance with lubricant is improved by devising shapes of an oil groove and the like for producing a flow pass of the lubricant.SOLUTION: A rolling bearing includes an inner ring 2, an outer ring 3, a rolling element 4 and a retainer 5. The inner ring 2 includes: an oil groove 6 reaching one side from the other side; and an oil hole 7 provided near an inner diameter surface while penetrating therethrough in an axial direction. Both of the oil groove 6 and the oil hole 7 include a surface with a shape where crests and valleys are alternately arranged in the axial direction.SELECTED DRAWING: Figure 2

Description

The present invention relates to rolling bearings that support the spindle of an aircraft jet engine.

In bearings for aircraft jet engines in which the spindle rotates at high speed, lubricating oil is supplied from the inner diameter of the inner ring as a lubrication method, the lubricating oil is circulated using centrifugal force, and the lubricating oil is used as a refrigerant to cool the spindle. Underrace lubrication is known.

In order to use this lubrication method, as shown in Patent Documents 1 and 2 below, a semicircular oil groove is formed in the inner diameter portion of the inner ring, and between the inner ring and the rotating shaft supported by the inner ring. Is provided with a flow path for lubricating oil composed of the oil groove.

Further, for bearings mainly used for machine tools, as shown in Patent Document 3 below, an oil supply / drainage mechanism that increases the surface area of a room in which lubricating oil is introduced to the outside of the bearing (extension of the raceway ring). There is an example in which the cooling effect of the bearing is enhanced.

USP 5,106,209 Japanese Unexamined Patent Publication No. 2006-90325 Japanese Unexamined Patent Publication No. 2012-87864

Bearings that rotate at high speeds cause problems such as seizure and wear that can cause damage if the condition of insufficient cooling continues. For this reason, it is required to improve the cooling efficiency as much as possible.

However, the underrace lubrication structure conventionally used for rolling bearings for jet engines has a simple shape of the oil groove, so there is still room for improvement from the viewpoint of cooling effect, and it is the most effective. It was not a structure.

Therefore, an object of the present invention is to provide a rolling bearing having improved cooling performance by the lubricating oil by devising the shape of an oil groove or the like that creates a flow path of the lubricating oil.

In order to solve the above problems, in the present invention,
An inner ring fixed to the outer circumference of the rotating shaft, an outer ring arranged on the outer circumference of the inner ring, a rolling element interposed between the raceway surfaces of the inner ring and the outer ring, and a cage for holding the rolling element are provided. It is a rolling bearing,
The inner ring has an oil groove extending from one end to the other end and an oil hole provided so as to penetrate in the axial direction near the inner diameter surface.
The oil groove and the oil hole provide a rolling bearing having a surface having a shape in which peaks and valleys are alternately arranged in the axial direction.

As a preferred embodiment of the rolling bearing, it is conceivable that the oil grooves are provided on the inner diameter surface of the inner ring at a constant pitch in the circumferential direction.

Further, the oil grooves and the oil holes are arranged in a staggered pattern with different phases in the circumferential direction and positions in the radial direction, and the top of the mountain and the bottom of the valley are curved surfaces having a convex arc shape and a concave arc shape. It is conceivable that each finished product.

The rolling bearing of the present invention includes an oil groove in which the inner ring penetrates in the axial direction near the inner diameter surface in addition to an oil groove for underrace lubrication.

Both the oil groove and the oil hole have a surface having a shape in which peaks and valleys are alternately arranged in the axial direction. If the threads and valleys are considered to be threads and valleys based on a reference thread-shaped metric screw with a thread angle of 60 °, for example, the groove surface of the oil groove or the hole surface of the oil hole The surface surface is about twice as large as that of a conventional oil groove having a semicircular cross section or a straight oil hole having a constant hole diameter.

Here, the relational expression of the following equation (1) holds for the amount of heat transfer at the position where the object and the object are in contact with each other.
Q = q * A (Equation 1)
_{q = h (T 1 -T W} ) ····· ( Equation 2)
Here Q: Heat quantity [W]
A: Cross section [m ² ]
q: Heat flux [W / m ² ]
h: Thermal conductivity [W / m ² ]
T ₁ : Surface temperature of the object [K]
_TW : Object temperature [K]

From the above equation, a proportional relationship is established between the surface area of the contact portion of the object and the amount of heat transfer. In the rolling bearing of the present invention, the surface areas of the oil groove and the oil hole formed in the inner ring and used as the flow path of the lubricating oil are greatly increased as compared with the oil groove and the oil hole without peaks and valleys as described above. Therefore, it can be expected that the cooling effect of the lubricating oil passed through the oil groove and the oil hole will increase at the same rate as the increase rate of the surface area.

If the oil grooves and the oil holes are arranged in a staggered pattern with different phases in the circumferential direction, each part of the inner ring in the circumferential direction can be cooled on average.

Furthermore, when the top of the peak and the bottom of the valley on the surface of the oil groove and the oil hole are finished into curved surfaces of convex arc shape and concave arc shape, respectively, there is no sharp edge at the bottom of the valley, and the bottom of the valley Stress concentration can be avoided.

In addition, the inner ring for rolling bearings of the present invention can adopt a method in which the first hole and the second hole are prepared holes and tapping is performed on those holes, so that the first hole and the second hole can be formed. Even small holes with a diameter of several millimeters can form regularly arranged peaks and valleys.

Further, since the inner diameter side of the inner ring material can be shaved until about half of the second hole is eliminated after tapping to form an oil groove on the inner diameter surface of the inner ring, an oil groove having alternating peaks and valleys on the surface can be formed. , Even if the oil groove is small in size, it can be easily formed.

It is sectional drawing which shows the main part of an example of the rolling bearing for an aircraft jet engine of this invention. It is a perspective view which shows the inner ring of the rolling bearing of FIG. It is an end view of the inner ring of FIG. It is a figure which shows the part of FIG. 3 enlarged. It is sectional drawing which follows the AA line of FIG. It is sectional drawing which shows the part of the oil hole of FIG. 5 enlarged. It is sectional drawing along the line BB of FIG. It is sectional drawing which shows the part of the oil groove of FIG. 7 enlarged. It is the enlarged cross-sectional view of a part which shows the example which made the top of a peak and the bottom of a valley of the surface of an oil groove and an oil hole into curved surfaces of a convex arc and a concave arc, respectively. It is sectional drawing which shows the outline of the manufacturing method of the inner ring of the rolling bearing of this invention. It is an end view of the ring-shaped inner ring material which processed the pilot hole for forming an oil hole and the pilot hole for forming an oil groove.

Hereinafter, embodiments of the rolling bearing of the present invention will be described with reference to FIGS. 1 to 12 of the accompanying drawings.

FIG. 1 shows an example of a rolling bearing for a jet engine of the present invention. Illustrated rolling bearing 1
Is a single row cylindrical roller bearing, the inner ring 2 fixed to the outer circumference of the rotating shaft (not shown), the outer ring 3 arranged on the outer circumference of the inner ring 2, and the raceway surface 2a of the inner ring 2 and the outer ring 3. A rolling element (cylindrical roller) 4 interposed between 3a and a cage 5 for holding the rolling element 4 are provided.

The inner ring 2 has a groove on the outer diameter surface into which the rolling element can enter, and the bottom of the groove is the raceway surface 2a. The inner ring 2 has an oil groove 6 extending from one end to the other end (see FIGS. 2 to 4 and 7) and an oil hole 7 (FIG. 2) provided so as to penetrate in the axial direction near the inner diameter surface of the inner ring 2. ~ (See FIG. 5).

As shown in FIGS. 2 and 3, the oil grooves 6 and the oil holes 7 are arranged in a staggered pattern with different phases in the circumferential direction. The illustrated oil groove 6 and the oil hole 7 are located at positions determined at the same angle in the circumferential direction.

As shown in FIGS. 6 and 8, the oil groove 6 and the oil hole 7 have a surface having a shape in which peaks 8 having a predetermined height and valleys 9 having a predetermined depth are alternately arranged in the axial direction. I have both. The ridges 8 and valleys 9 of the example are ridges and valleys of female threads provided with a predetermined lead angle.

The oil hole 7 is provided at a position where a problem in strength does not occur in consideration of the maximum shear stress depth of the portion where the oil groove 6 is installed.

The peaks 8 and valleys 9 on the surfaces of the oil groove 6 and the oil hole 7 are formed by the following method. In the method, first, as shown in FIG. 10, a pilot hole 11 for an oil hole 7 having a predetermined hole diameter is machined in a ring-shaped inner ring material 10 having an inner diameter smaller than the inner diameter of the inner ring 2 to be manufactured. To do.

At this time, in the oil groove 6, a pilot hole 12 (see FIG. 11) having a predetermined hole diameter is machined in the inner ring material 10 with a drill D, and a part (preferably about half) of the pilot hole 12 is formed in a subsequent step. Formed by the method of removal.

The pilot holes 11 and 12 are formed so as to be staggered alternately in the circumferential direction by shifting the positions in the radial direction and further shifting the positions in the circumferential direction. Then, after finishing the processing of the prepared holes 11 and 12 for the inner ring material 10, next, tap processing is performed to form a female screw on the inner surface of the prepared holes 11 and 12.

Depending on the size of the inner ring (for example, for products with an inner ring width of 11 mm or more), the machining of pilot holes 11 and 12 with a drill and the machining of female threads on the inner surface (hole surface) of the pilot hole with a thread cutting tap may be performed on the inner ring material. It is preferable to form the 10 in half facing each other from one end side and the other end side.

After finishing the processing of the female threads on the inner surfaces of the prepared holes 11 and 12, the inner diameter side of the inner ring material 10 is next cut so that an inner diameter surface having a predetermined diameter can be obtained.

By cutting the inner diameter side of the inner ring material 10 to the position of the virtual circle S indicating the position of the inner ring surface of the inner ring shown by the alternate long and short dash line in FIG. 11, the oil groove 6 is opened to the target oil groove 6, that is, the inner diameter surface of the inner ring 2. Moreover, it is possible to form an oil groove 6 in which peaks and valleys alternately connected in the axial direction exist on the surface.

It is preferable that the inner ring material 10 has an outer diameter surface processed in advance so that the pilot holes 11 and 12 and the inner diameter surface can be finished with reference to the outer diameter surface. It is also possible to process the pilot holes 11 and 12, the female threads on the inner surfaces of the prepared holes 11 and 12, and finish the inner diameter surface first, and then process the outer diameter surface last.

As shown in FIG. 9, the female threads provided in the prepared holes 11 and 12 are stress-concentrated at the valley bottom, assuming that the top of the ridge 8 is formed by a curved surface of a convex arc and the bottom of the valley 9 is formed by a curved surface of a concave arc. Can be avoided.

For peaks and valleys of such shape, the top of the peak of the threaded tap is a curved surface of a convex arc, the bottom of the valley is a curved surface of a concave arc, and the shape of the top of the peak and the bottom of the valley of the threaded tap is transferred to the pilot hole. To form.

For rolling bearings assuming a rolling bearing with an inner ring inner diameter of 110 mm, a raceway groove bottom diameter (trajectory surface diameter) formed on the outer diameter surface of the inner ring is 120 mm, and a rolling element (cylindrical roller) diameter of φ12 mm. The inner ring of the was processed using a machining center.

As shown in FIGS. 10 and 11, the processing procedure is as follows: first, the outer diameter surface of the ring-shaped inner ring material 10 having an inner diameter of 100 mm and the raceway grooves provided on the outer diameter surface are processed, and then the processed outer diameter is processed. The pilot hole 11 for the oil hole 7 and the pilot hole 12 for the oil groove 6 were drilled at predetermined positions with the surface as a reference.

The pilot holes 11 and the pilot holes 12 were machined so that the phases in the circumferential direction and the positions in the radial direction were different from each other, and the pilot holes 11 and the pilot holes 12 were alternately staggered at a constant pitch in the circumferential direction.

Further, a thread cutting tap (not shown) was cut into the prepared hole 11 and the prepared hole 12, and a female screw having a thread angle of 60 ° was machined on the inner surface of the prepared hole. The thread cutting tap for cutting into the prepared hole 11 had an outer diameter of 1.7 mm, and the thread cutting tap for cutting into the prepared hole 12 had an outer diameter of 2.6 mm.

The diameters of the prepared hole 11 and the prepared hole 12 are φ1.4 mm for the prepared hole 11 and φ2.0 mm for the prepared hole 12.

Further, in the case of this specification, the maximum shear stress depth is at a position of about 0.30 mm inward in the radial direction from the raceway surface, so the pilot hole 12 is machined at a position 3 mm or more inward in the radial direction from the raceway surface.
Further, the prepared hole 11 was machined at a position separated from the raceway surface by 2 mm or more.

After that, the inner diameter surface was finished based on the outer diameter surface, and the excess portion on the inner diameter side was scraped to the position of the virtual circle S in FIG.

Through the above steps, an oil groove 6 exists on the inner diameter surface and an oil hole 7 exists near the inner diameter surface, and the oil groove 6 and the oil hole 7 have peaks and valleys arranged alternately in the axial direction on the surface. I got an inner ring.

A rolling bearing using this inner ring is used in combination with an oil supply / drainage mechanism that supplies and circulates lubricating oil to the oil groove 6 and the oil hole 7.

1 Rolling bearing 2 Inner ring 2a Race surface 3 Outer ring 3a Race surface 4 Rolling element 5 Cage 6 Oil groove 7 Oil hole 8 Mountain 9 Valley 10 Inner ring material 11, 12 Pilot hole D Drill S Virtual circle indicating the position of the inner ring surface of the inner ring

Claims (4)

Holds an inner ring (2), an outer ring (3), a rolling element (4) interposed between the raceway surfaces (2a, 3a) of the inner ring (2) and the outer ring (3), and the rolling element (4). Equipped with a cage (5)
The inner ring (2) has an oil groove (6) extending from one end to the other end and an oil hole (7) provided so as to penetrate in the axial direction near the inner diameter surface.
A rolling bearing in which the oil grooves (6) and oil holes (7) are provided together with a surface having a shape in which peaks (8) and valleys (9) are alternately arranged in the axial direction. The rolling bearing according to claim 1, wherein the oil groove (6) is provided on the inner diameter surface of the inner ring (2) at a constant pitch in the circumferential direction. The rolling bearing according to claim 1 or 2, wherein the oil grooves (6) and oil holes (7) are arranged in a staggered manner with different phases in the circumferential direction and positions in the radial direction. Any one of claims 1 to 3 in which the top of the peak (8) of the oil groove (6) and the oil hole (7) is formed on a curved surface of a convex arc, and the bottom of the valley (9) is formed on a curved surface of a concave arc. Rolling bearings described in.

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