WO2012157021A1

WO2012157021A1 - Two-stage cross roller bearing

Info

Publication number: WO2012157021A1
Application number: PCT/JP2011/002719
Authority: WO
Inventors: 晃啓横山; 堀内　雅士; 直巳白澤
Original assignee: 株式会社ハーモニック・ドライブ・システムズ
Priority date: 2011-05-16
Filing date: 2011-05-16
Publication date: 2012-11-22
Also published as: KR20140024008A; JPWO2012157021A1; TWI545272B; CN103534495B; CN103534495A; TW201248031A

Abstract

In a two-stage cross roller bearing (1), an outer ring (11), a middle ring (12), and an inner ring (13) are concentrically arranged, and the size of an outer roller (15), which is inserted in an outer raceway (14) between the outer ring (11) and the middle ring (12), is smaller than the size of an inner roller (17), which is inserted in an inner raceway (16) between the middle ring (12) and the inner ring (13). The center (L2) of the inner roller (17) is offset in the direction of a central axis (1a) with respect to the center (L1) of the outer roller (15). The thickness t (12) of the middle ring (12) in the radial direction is at least twice the thickness t (11) of the outer ring (11) in the radial direction. The preload deformation of the middle ring (12) can be minimized, and a two-stage cross roller bearing capable of ensuring the smooth rotation of the inner and outer rollers (15, 17), can be achieved.

Description

2-stage cross roller bearing

The present invention relates to a compact and compact two-stage cross roller bearing having a structure in which two sets of cross roller bearings are arranged concentrically.

A cross roller bearing is a bearing portion in which a roller is inserted in an annular raceway having a rectangular cross section formed between an inner ring and an outer ring in a state where center axes are alternately orthogonal, and both radial force and thrust force act. Is often used.

The present applicant has proposed a flat multi-stage cross roller bearing with high support rigidity capable of taking out the rotation of two concentric axes in Patent Document 1. The multi-stage cross roller bearing has a first cross roller bearing and a second cross roller bearing, and the second cross roller bearing is disposed concentrically inside the first cross roller bearing, and the first cross roller bearing The inner ring of the roller bearing and the outer ring of the second cross roller bearing are formed from an intermediate ring which is a single annular member. The inner ring side raceway groove of the first cross roller bearing is formed on the circular outer peripheral surface of the intermediate ring, and the outer ring side raceway groove of the second cross roller bearing is formed on the circular inner peripheral surface of the annular member. Patent Document 2 proposes a multistage ball bearing in which ball bearings are arranged in multiple stages concentrically.

WO2003 / 050428 brochure JP 2000-27857 A

In a two-stage cross roller bearing in which the cross roller bearings are concentrically arranged, a large preload acts on the inner ring of the outer cross roller bearing and the intermediate ring that functions as the outer ring of the inner cross roller bearing. For this reason, preload deformation occurs in the intermediate wheel, and there is a problem that smooth rotation of the cross roller bearing at each stage cannot be ensured.

In view of this point, an object of the present invention is to propose a two-stage cross roller bearing capable of suppressing the preload deformation of the intermediate wheel functioning as an inner ring and an outer ring and ensuring smooth rotation of each cross roller bearing. .

In order to solve the above problems, the two-stage cross roller bearing of the present invention is:
An outer ring, an intermediate ring arranged concentrically inside the outer ring, an inner ring arranged concentrically inside the intermediate ring, an annular ring having a rectangular cross section formed between the outer ring and the intermediate ring An outer track, a plurality of outer rollers inserted in the outer track in a freely rollable state, an annular inner track having a rectangular cross section formed between the intermediate ring and the inner ring, and the inner side A plurality of inner rollers inserted in a freely rolling manner in the track,
The roller size of the inner roller is smaller than the roller size of the outer roller,
The roller center of the inner roller is at a position offset in the direction along the axis with respect to the roller center of the outer roller.

Here, the offset amount of the roller center of the inner roller with respect to the roller center of the outer roller is from 1/2 of the track width of the inner track to 1 / of the added value of the track width and the track width of the outer track. It can be a value in the range up to 2. If the offset amount is less than the value within this range, the preload deformation of the intermediate wheel cannot be sufficiently suppressed, and there is a risk that smooth rotation of the inner and outer cross roller bearings cannot be ensured. Further, even if the offset amount is larger than the value within this range, further improvement in the effect of suppressing the preload deformation of the intermediate wheel by the offset cannot be obtained, and the width dimension in the direction of the central axis of the two-stage cross roller bearing Becomes larger, which is disadvantageous for flattening of the two-stage cross roller bearing.

In order to make the two-stage cross roller bearing flat while effectively suppressing the preload deformation of the intermediate wheel, it is desirable that the offset amount be ½ of the track width of the outer track.

Next, in order to reliably prevent the preload deformation of the intermediate wheel, the radial thickness between the circular inner peripheral surface and the circular outer peripheral surface of the intermediate wheel is set at least from the circular inner peripheral surface of the outer ring. It is desirable that the thickness in the radial direction between the circular outer peripheral surface is doubled.

On the other hand, in order to improve the assemblability of the two-stage cross roller bearing, the outer race and the inner race are formed at positions close to one end face of the outer race, the intermediate race and the inner race, and the intermediate race It is desirable that an insertion hole for inserting a roller is formed in each of the end surfaces of the ring and the inner ring.

In the two-stage cross roller bearing of the present invention, a large-diameter outer cross roller bearing is constituted by the outer ring, the intermediate ring, the outer raceway, and the outer roller, and a small-diameter inner cross roller is constituted by the intermediate ring, the inner race, the inner raceway, and the inner roller. A bearing is constructed. A large-diameter outer cross roller bearing located on the outside has a large roller size, and a small-diameter inner cross-roller bearing located on the inside has a small roller size. Therefore, in a state where the two-stage cross roller bearing is assembled, it is possible to balance the preload stress acting from the inside and the outside on the intermediate wheel which is a common part of the inner and outer cross roller bearings.

In addition, since the roller center of the outer cross roller bearing and the roller center of the inner cross roller bearing are offset from each other in the direction of the center axis, compared to the case where they are positioned in the same plane in the radial direction, Preload deformation that occurs in the intermediate wheel can be reduced. As a result, the preload deformation of the intermediate wheel in a state where the two-stage cross roller bearing is assembled can be suppressed, and smooth rotation of the inner and outer cross roller bearings can be ensured.

It is the end view and longitudinal cross-sectional view which show the two-stage cross roller bearing to which this invention is applied.

Embodiments of a two-stage cross roller bearing to which the present invention is applied will be described with reference to the drawings. As shown in FIG. 1, the two-stage cross roller bearing 1 includes an outer ring 11, an intermediate ring 12 arranged concentrically inside the outer ring 11, and an inner ring 13 arranged concentrically inside the intermediate ring 12. It has. An annular outer raceway 14 having a rectangular cross section is formed between the outer race 11 and the intermediate race 12, and a plurality of outer rollers 15 roll on the outer raceway 14 in a state where the central axes are alternately orthogonal to each other. It is inserted freely. An annular inner raceway 16 having a rectangular cross section is also formed between the intermediate ring 12 and the inner race 13, and a plurality of inner rollers 17 are inserted into the inner raceway 16 with the central axes alternately orthogonal to each other. Has been.

An insertion hole 12f for inserting the outer roller 15 into the outer track 14 is formed in one annular end surface 12a of the intermediate ring 12, and this insertion hole 12f is sealed by a stopper 18. Similarly, an insertion hole 13 f for inserting the inner roller 17 into the inner track 16 is formed in the annular end surface 13 a on the same side of the inner ring 13, and the insertion hole 13 f is sealed by a plug 19.

Screw

holes

21 and 22 are formed in the

annular end surfaces

11a and 11b on both sides of the outer ring 11 at regular angular intervals in the circumferential direction, respectively. These are screw holes of a predetermined depth extending in the direction of the bearing center axis 1a. A plurality of

screw holes

23 and 24 are also formed in the annular end faces 12a and 12b on both sides of the intermediate ring 12 at predetermined angular intervals in the circumferential direction. These

screw holes

23 and 24 are also screw holes having a predetermined depth extending in the direction of the bearing center axis 1a. Similarly, a plurality of

screw holes

25 and 26 are formed at predetermined angular intervals in the circumferential direction on the annular end faces 13a and 13b on both sides of the inner ring 13 as well. A central through hole 13g is formed in the inner ring 13, and a screw insertion hole 27 is provided at a predetermined angular interval in the circumferential direction in an annular flange 13h protruding inward from the circular inner peripheral surface with a constant width. Is formed. Using these screw holes 21 to 26 and the screw insertion hole 27, another member (not shown) can be connected and fixed to the end faces on both sides of the outer ring 11, the intermediate ring 12 and the inner ring 13.

Here, the roller size of the inner roller 17 is smaller than the roller size of the outer roller 15, and the outer cross roller bearing has a larger bearing load capacity. The roller center L2 of the inner roller 17 is offset from the roller center L1 of the outer roller 15 in the direction along the bearing center axis 1a.

In this example, in order to make the two-stage cross roller bearing 1 flat while effectively suppressing the preload deformation of the intermediate wheel 12, the offset amount Δ is ½ of the track width w (14) of the outer track 14. The roller center L2 is offset from the roller center L1 toward the annular end faces 11a to 13a. The offset amount Δ is in the range from 1/2 of the track width w (16) of the inner track 16 to 1/2 of the sum of the track width w (16) and the track width w (14) of the outer track 14. It is desirable to set the value of.
w (16) / 2 <Δ <{w (16) + w (14)} / 2

In order to prevent the preload deformation of the intermediate ring 12 with certainty, the thickness t (12) in the radial direction between the circular inner peripheral surface 12d and the circular outer peripheral surface 12e of the intermediate ring 12 has a circular shape of the outer ring 11. The radial thickness t (11) between the inner peripheral surface 11d and the circular outer peripheral surface 11e is set to be twice or more.

Further, the

annular end surfaces

11a, 12a, 13a on the same side of the outer ring 11, the intermediate ring 12, and the inner ring 13 are located on substantially the same plane, and the outer race 14 is more annular end surface than the

annular end surfaces

11b, 12b. It is in a position close to the side of 11a, 12a. Further, the inner track 16 is located closer to the

annular end surfaces

12a and 13a than the

annular end surfaces

12b and 13b. As described above, the

insertion holes

12f and 13f are formed in the

annular end faces

12a and 13a. In this way, the outer track 14 and the inner track 16 are brought close to the

annular end surfaces

12a and 13a on the roller insertion side in the direction of the bearing center axis 1a. Therefore, the assemblability of the two-stage cross roller bearing 1 and the workability of the roller insertion work can be improved.

Claims

An outer ring (11),
An intermediate wheel (12) arranged concentrically inside the outer ring (11);
An inner ring (13) arranged concentrically inside the intermediate ring (12);
An annular outer raceway (14) having a rectangular cross section formed between the outer ring (11) and the intermediate ring (12);
A plurality of outer rollers (15) inserted into the outer raceway (14) in a rollable state;
An annular inner raceway (16) having a rectangular cross section formed between the intermediate ring (12) and the inner ring (13);
A plurality of inner rollers (17) inserted into the inner raceway (16) in a rollable state;
The roller size of the inner roller (17) is smaller than the roller size of the outer roller (15),
The roller center (L2) of the inner roller (17) is offset from the roller center (L1) of the outer roller (15) in a direction along the bearing center axis (1a). 2 stage cross roller bearing (1).
In claim 1,
The offset amount (Δ) of the roller center (L2) of the inner roller (17) with respect to the roller center (L1) of the outer roller (15) is ½ of the track width of the inner track (16). A two-stage cross roller bearing (1) characterized in that the value is within a range up to ½ of the sum of the width and the track width of the outer track (14).
In claim 1,
The offset amount (Δ) of the roller center (L2) of the inner roller (17) with respect to the roller center (L1) of the outer roller (15) is ½ of the track width of the outer track (14). Features two-stage cross roller bearing (1).
In claim 1,
The thickness in the radial direction between the circular inner peripheral surface and the circular outer peripheral surface of the intermediate ring (12) is at least the radial thickness between the circular inner peripheral surface and the circular outer peripheral surface of the outer ring (11). Two-stage cross roller bearing (1) characterized in that it is twice the height.
In any one of claims 1 to 4,
The outer raceway (14) and the inner raceway (16) are formed at positions close to one end face of the outer race (11), the intermediate race (12) and the inner race (13),
Insertion holes (12f, 13f) for inserting rollers are respectively formed on the end surfaces of the intermediate ring (12) and the inner ring (13), and these insertion holes are sealed by plugs (18, 19). Two-stage cross roller bearing (1) characterized by the above.