JP2022136891A - Pressurization structure of ball bearing, and manufacturing method for rotational shaft - Google Patents

Abstract

To facilitate the application of pressurization to a steel ball of a bearing that supports a shaft.SOLUTION: A pressurization structure of a ball bearing has: an inner race 2 fixed to a rotational shaft 1; an outer race 6 that is arranged in a mounting hole 4 provided in a housing 3, and holds a steel ball 5 between itself and the inner race 2; and a first ring nut 7 that has a male screw 7a to be screwed into a female screw 4a on the inner periphery of the mounting hole 4, and is tightened so as to apply a predetermined pressure to the steel ball 5 between the inner race 2 and the outer race 6 by rotation of the male screw 7a.SELECTED DRAWING: Figure 1

Description

The present invention relates to a pressurized structure for ball bearings and a method for manufacturing a rotary shaft.

Conventionally, there are fixed-position preloading and constant-pressure preloading for bearing preloading, and fixed-position preloading is often used. In addition, when supporting the shaft that makes up the gimbal mechanism used to support precision equipment, etc., the thickness and number of shims sandwiched between the housing and the outer ring are required to eliminate backlash between the inner ring, steel ball, and outer ring of the bearing. has been adjusted to position the outer ring in the axial direction and adjust the amount of preload on the steel balls.

Further, Patent Document 1 discloses, as a bearing structure related to the present invention, a structure in which a double-row bearing that supports a steering shaft of an automobile is fixed to the steering shaft and is prevented from loosening by a so-called double nut.

JP 2014-040210 A

However, the adjusting method using the shims requires complicated and delicate work, and therefore has a problem that it must rely on the tactile sensation of a skilled operator.
Moreover, the bearing support structure described in Patent Document 1 relates to the adjustment of one bearing used to support the steering shaft of an automobile. It is not directly applicable. Also, the technique for eliminating backlash between double-row bearings cannot be directly applied to the structure for eliminating backlash between the inner and outer rings of the bearing.

SUMMARY OF THE INVENTION An object of the present invention is to apply appropriate pressure between the inner and outer races of a bearing and steel balls.

In order to solve the above problems, the present invention proposes the following means.
A ball bearing pressurization structure according to a first aspect of the present invention holds a steel ball between an inner race fixed to a rotating shaft and a mounting hole provided in a housing to hold a steel ball between the inner race. An outer race and a male screw that engages the female screw on the inner periphery of the mounting hole are tightened so that the steel balls between the inner race and the outer race are pressurized by the rotation of the male screw. 1 ring nut.

In a method for manufacturing a rotating shaft according to a second aspect of the present invention, an inner race is fixed to the rotating shaft, and an outer race holding steel balls between the inner race and the inner race is arranged in a mounting hole provided in a housing. a method of manufacturing a rotating shaft comprising: fixing the inner race to the rotating shaft; disposing the outer race in the mounting hole; and attaching a first ring nut to the internal thread of the mounting hole. A step of moving the outer race in a direction along the rotation axis by screwing and rotating a male thread on the outer periphery of the inner race and the outer by tightening the first ring nut with a predetermined torque. and applying pressure in the direction of the rotation axis to the steel ball between the race.

According to the present invention, an appropriate pressurization can be applied between the outer race, the inner race and the steel balls of the ball bearing.

1 is a vertical cross-sectional view of a minimal configuration example of a pressurized structure for a ball bearing according to the present invention; FIG. 1 is a longitudinal sectional view of one embodiment of the present invention; FIG. Figure 3 is a detailed view of the bearing portion of Figure 2; FIG. 3 is an explanatory diagram of a gap in the bearing portion of FIG. 2; FIG. 5 is an explanatory diagram showing one stage of gap adjustment shown in FIG. 4 ; FIG. 5 is an explanatory diagram showing the next stage of the gap adjustment shown in FIG. 4; FIG. 3 is a longitudinal sectional view showing a state after pressurization is applied to the bearing of FIG. 2; FIG. 4 is an explanatory diagram of a tightening tool for a ring nut in one embodiment; FIG. 9 is a plan view of one embodiment of the ring nut shown in FIG. 8;

A minimal configuration example of the present invention will be described with reference to FIG.
The pressurized structure of this ball bearing consists of an inner race 2 fixed to a rotating shaft 1 and an outer race arranged in a mounting hole 4 provided in a housing 3 and holding a steel ball 5 between the inner race 2 and the inner race 2. 6 and a male screw 7a screwed into the female screw 4a on the inner circumference of the mounting hole 4. By rotating the male screw 7a, a predetermined pressure is applied to the steel balls 5 between the inner race 2 and the outer race 6. and a first ring nut 7 tightened to provide.

According to the above configuration, by rotating the first ring nut 7 with a predetermined torque, the outer race 6 can be moved along the rotating shaft 1, and the torque applied to the first ring nut 7 can be increased. The steel balls 5 between the outer race 6 and the inner race 2 can be held in a state of being pressurized in the direction of the rotating shaft 1 according to the torque.

In the minimum configuration example of the rotating shaft manufacturing method according to the present invention, the inner race 2 is fixed to the rotating shaft 1, and the housing 3 is provided with the outer race 6 for holding the steel balls 5 between the inner race 2 and the inner race 2. A method for manufacturing a rotating shaft disposed in a mounting hole 4 formed by a mounting hole, comprising the steps of: fixing the inner race 2 to the rotating shaft 1; disposing the outer race 6 in the mounting hole 4; a step of moving the outer race 6 in a direction along the rotation axis 1 by screwing a male thread 7a on the outer periphery of the first ring nut 7 into the female thread 4a on the inner periphery of the ring nut 4 and rotating the first ring nut 7; and a step of applying pressure to the steel ball 5 between the inner race 2 and the outer race 6 in the direction of the rotating shaft 1 by tightening the ring nut 7 with a predetermined torque.

According to the above configuration, by rotating the first ring nut 7 with a predetermined torque, the outer race 6 can be moved along the rotating shaft 1, and the torque applied to the first ring nut 7 can be increased. The steel balls 5 between the outer race 6 and the inner race 2 can be pressurized in the direction of the rotating shaft 1 according to the torque.

A configuration according to a first embodiment of the present invention embodying FIG. 1 will be described with reference to FIGS. 2 to 8. FIG. In addition, the same code|symbol is attached|subjected to the structure common to FIG. 1 in a figure, and description is simplified.
As shown in FIGS. 2 and 3, the housing 3 has a cylindrical appearance and has bearings 10 at its left and right ends. Note that in one embodiment, the bearing as a whole, which is composed of the inner race 2, the outer race 6, and the steel balls 5, is called a bearing 10. As shown in FIG.
Thus, the shaft 1 is supported between the bearings 10 provided at one end and the other end.

The inner race 2 of the bearing 10 is attached to the shaft 1 with a shaft fixing nut 11 . More specifically, male threads 12 are formed on both ends of the shaft 1, and a female thread 13 on the inner circumference of the shaft fixing nut 11 is screwed into the male threads 12, whereby a large diameter portion 14 in the center of the shaft 1 and the shaft are screwed together. The inner race 2 is sandwiched between the fixing nut 11 and the shaft 1 and the inner race 2 are integrally connected.

A portion of the outer race 6 of the bearing 10 has a large-diameter flange portion 61, and a first male screw 7a is screwed into this flange portion 61 and the female screw 4a of the mounting hole 4 at the end of the housing 3. is axially positioned by the ring nut 7 of the Further, the first ring nut 7 is applied with an outward force along the rotating shaft 1 by screwing the external thread 15a on the outer periphery of the second ring nut 15 into the internal thread 4a. and fixed in a non-rotating state.
The preload adjustment and management of the bearing 10 is performed by tightening the first ring nut 7, and the bearing 10 is fixed in a predetermined pressurized state by tightening the second ring nut 15 after the adjustment.

A process of attaching the bearing 10 to the shaft 1 and applying pressure to the steel balls 5 of the bearing 10 to manufacture the rotary shaft will be described.
A first ring nut 7 and a second ring nut 15 are screwed into the mounting holes 4 at both ends of the housing 3, and are pushed inward to such an extent that they do not interfere with the side surface of the outer race 6 of the bearing 10 to be arranged in a later step. Deploy.

The shaft 1 is placed in the housing 3, its end is inserted into the inner race 2, and the inner race 2 is fixed to the shaft 1 by screwing the shaft fixing nut 11. As shown in FIG.
As shown in FIG. 4, before the first ring nut 7 is tightened, the steel ball 5 is arranged at a position substantially in the center between the outer race 6 and the inner race 2. Between the inner race 2 and the steel ball 5, there are gaps .delta.o and .delta.i.

When the first ring nut 7 is tightened and moved toward the axial end (leftward in FIG. 4), it approaches the side surface of the outer race 6 as shown in FIG. In this state, a gap of l exists between the side surface of the outer race 6 and the side surface of the first ring nut 7 .
From this state, when the first ring nut 7 is further tightened, the gaps δo and δi become smaller, and as shown in FIG. The inner race 2 (specifically, the side surface of the groove on its outer circumference) and the steel balls 5 are brought into contact with each other.

When the first ring nut 7 is further tightened from the state shown in FIG. 6, the outer race 6, the inner race 2, and the steel balls 5 are slightly elastically deformed due to the thrust corresponding to the tightening torque, preload is applied, and tightening becomes impossible. As shown in FIG. 7, the contact point between the inner race 2 and the steel ball 5 and the contact point between the outer race 6 and the steel ball 5 are arranged on the dashed line C. , the bearing 10 is positioned on the shaft 1.

The tightening of the first ring nut 7 is alternately repeated slightly on one end side and the other end side of the shaft 1, so that the bearings 10 on both ends of the shaft 1 can be evenly given a predetermined pressure. desirable.

After adjusting the tightening torque of the first ring nut 7 at both ends of the shaft 1 in this way, as shown in FIG. Tighten to move further toward the axial end. By tightening the second ring nut 15, elastic deformation of the first ring nut 7, the second ring nut 15, the male threads 7a and 15a on the outer circumference thereof, and the female thread 4a on the inner circumference of the mounting hole 4 is performed. Thus, the contact pressure between the male threads 7a, 15a and the female thread 4a is maintained, and the first ring nut 7 can be fixed at a position where a predetermined pressurization occurs.
By applying a predetermined pressurization through the above steps, it is possible to manufacture a rotary shaft having the shaft 1 supported by the bearings 10 at both ends in the housing 3 .

The first ring nut 7 is tightened, for example, as shown in FIGS. 8 and 9, through holes 7b (two are shown in FIG. are provided in a plurality in the circumferential direction as shown in FIG. It can be rotated using a tool provided at the position. The arm 21 also connects the tip of the central shaft 22 (formed in the shape of a hexagon bolt, for example) to a torque wrench 23 having a hole in the shape of a hexagon nut. A tool equipped with a torque limiting mechanism) is inserted into the arm 24 and the handle 25 at the tip of the arm 24 is operated. Instead of the torque wrench 23, a tool such as a torque driver (not shown) capable of driving the shaft with a predetermined torque may be used for rotation.
Further, as shown in FIG. 9, the first ring nut 7 is provided with arcuate slits 7c (at positions avoiding the through holes 7b) at a plurality of locations in the circumferential direction, and the second ring nut 15 Also, a through hole 7b similar to the through hole 7b of the first ring nut 7 is provided, and a pin 20 of a tool as shown in FIG. This can be done by reaching the position of the nut 15, inserting it into the through hole 7b, and rotating the tool in the same manner as the first ring nut 7. Alternatively, the second ring nut 15 can be operated by a tool inserted through an opening (indicated by reference numeral 3a in FIG. 2) provided in a portion of the cylindrical housing 3. FIG.

According to the structure that applies preload using the ring nut described in one embodiment, the preload amount of the bearing 10 can be adjusted and managed by the torque for tightening the first ring nut 7 .
The thrust generated in the first ring nut 7 can be calculated from the tightening torque and the nominal diameter according to the following equation (1).
F=T/(K・d) (1) Formula F: Thrust T: Tightening torque d: Nominal diameter K: Torque coefficient

The amount of preload can be estimated by using the thrust force obtained by the above equation (1) and referring to the characteristic curve showing the relationship between the axial load and the axial displacement of the bearing. From the above, the preload of the bearing, which was adjusted and managed by the operator's tactile sensation, can be digitized with a tool such as a precision torque screwdriver that can adjust the shaft torque to a predetermined value, and can be easily adjusted and managed. be able to manage.
The above characteristic curve shows the amount of displacement of the bearing that increases as the load increases due to a phenomenon in which elastic deformation occurs in the contact area between the bearing ring and the rolling element when a load is applied to the bearing. , is also called Axial Load-Axial Displacement.

Although the first and second types of ring nuts are used in the above embodiment, a male thread may be provided on the outer periphery of the outer race and screwed into a female thread on the inner periphery of the housing. In this case, since the outer peripheral portion of the outer race also serves as the first ring nut, the ring nut may be of one type (corresponding to the second ring nut in one embodiment) for preventing rotation of the outer race. Enough.

As described above, the embodiment of the present invention has been described in detail with reference to the drawings, but the specific configuration is not limited to this embodiment, and design changes and the like are included within the scope of the present invention.

INDUSTRIAL APPLICABILITY The present invention can be used for a bearing pressurization structure and a method for manufacturing a rotating shaft.

1 Rotating axis (shaft)
2 inner race 3 housing 3a opening 4 mounting hole 4a female screw 5 steel ball 6 outer race 7 (first) ring nut 7a male screw 7b through hole 7c slit 10 bearing 11 shaft fixing nut 12 male screw 13 female screw 14 large diameter portion 15 third 2 ring nut 61 flange

Claims (7)

an inner race fixed to the rotating shaft;
an outer race arranged in a mounting hole provided in the housing and holding a steel ball between the inner race and the inner race;
A first ring nut having a male thread that engages the female thread on the inner periphery of the mounting hole, and is tightened so as to apply a predetermined pressure to the steel balls between the inner race and the outer race as the male thread rotates. When,
ball bearing pressurized structure. a second ring nut that is screwed into the internal thread of the mounting hole and exerts a force in a direction along the rotation axis between itself and the first ring nut;
The pressurized structure for a ball bearing according to claim 1. The outer race is integrally provided with an annular support member having a diameter larger than the inner diameter of the first ring nut,
The ball bearing pressurization structure according to claim 1 or 2. The inner race is provided at one end and the other end of the rotating shaft,
The outer race is provided on the outer circumference of each of the inner races at the one end and the other end,
one of the first ring nuts contacts a portion of the outer race at the one end to apply pressure in one direction along the rotation axis;
the other of the first ring nut contacts a portion of the outer race at the other end and applies pressure in the other direction along the rotation axis;
A pressurized structure for a ball bearing according to any one of claims 1 to 3. having a male thread formed on the outer circumference of the outer race instead of the male thread formed on the outer circumference of the first ring nut;
applying pressure to the outer race by screwing the male thread into the female thread of the mounting hole;
The pressurized structure for a ball bearing according to claim 1. A method for manufacturing a rotating shaft, wherein an inner race is fixed to the rotating shaft, and an outer race for holding steel balls between the inner race and the inner race is arranged in a mounting hole provided in a housing,
fixing the inner race to a rotating shaft;
placing the outer race in the mounting hole;
a step of moving the outer race in a direction along the rotation axis by screwing the external thread on the outer periphery of the first ring nut into the internal thread on the mounting hole and rotating the first ring nut;
a step of applying pressure in a direction along the rotation axis to the steel balls between the inner race and the outer race by tightening the first ring nut with a predetermined torque;
A manufacturing method of a rotary shaft having The inner race and the outer race are provided at one end and the other end of the rotating shaft, respectively,
By tightening the first ring nut at one end of the rotating shaft with a predetermined torque, the steel balls between the inner race and the outer race at one end of the rotating shaft are pressurized in the direction along the rotating shaft. and
a step of tightening the first ring nut at the other end of the rotating shaft with a predetermined torque to apply pressure to the steel balls between the inner race and the outer race in a direction along the rotating shaft;
By alternately executing
applying a predetermined pressure to the steel ball at one end of the rotating shaft and the steel ball at the other end of the rotating shaft;
The manufacturing method of the rotating shaft according to claim 6.

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