Design of O-shaped Stamped Cage for Cylindrical Roller Bearings

Abstract: This paper introduces the structure and selection principles of structural parameters for the O-shaped cage of cylindrical roller bearings. Based on the geometric relationship of the cage, the theoretical calculation formula for the corresponding outer lock and inner lock diameters under two states of the cage's outer lock and inner lock is mainly derived.

Keywords: cylindrical roller bearings; O-shaped cage; Design; External lock; Internal lock

Symbol Description

B -- Ring width

Bc -- Cage width

DC -- Inner diameter of cage

Dc -- Outer diameter of cage

Dcp - Center diameter of cage pocket hole

Dpw - Diameter of the pitch circle of the roller group

Dw - Roller diameter

Ks - coefficient

L1-- Length of the middle groove of the cage window hole

Lc -- Length of cage window hole

Lw -- Roller length

S -- Thickness of retaining frame steel plate

Sk -- Width of the lock opening of the cage window hole

Sk1- Width of the middle groove of the cage window hole

Z - Number of rollers (number of cage window holes)

1. Cage structure and classification

The O-shaped cage of cylindrical roller bearings has the characteristics of simple structure, good processability, and easy implementation of assembly automation, and has been widely used in production. The structure of the O-ring cage is shown in Figure 1.

According to the relationship between the center diameter Dcp of the cage pocket and the pitch circle diameter Dpw of the roller group, the cage can be divided into two states: internal locking and external locking. When Dcp<Dpw, the cage is in an externally locked state, and the rollers are fixed by the outer diameter of the cage and the outer ring raceway; When Dcp>Dpw, the cage is in an internally locked state, and the rollers are fixed by the inner diameter of the cage and the inner ring raceway.

Figure 1 O-shaped cage structure diagram

2. Determination of cage size

2.1 Selection of Steel Plate Thickness S

The calculation formula for the thickness S of the cage steel plate is

S=KsDw, (1)

For the 2.5 diameter series, Ks=0.10-0.12; For the 3.6 diameter series, Ks=0.08 to 0.10. The accuracy of the calculated value of S obtained from equation (1) is 0.1 mm, and then the standard thickness close to the S value is selected based on the standard thickness of the cold-rolled steel strip (plate). The standard thickness of cold-rolled steel strip (plate) is 0.5, 0.6, 0.7, 0.8, 1.0, 1.2, 1.5, 2.0, 2.5, 3.0 mm.

2.2 Determination of Lc, Bc, L1, Sk, Sk1

Lc=Lw+ ε 1, (2)

ε Take 0.2-0.4 mm.

Bc=Lc+(3-4) S, (3)

And it must meet the requirement of Bc ≤ B-1.5.

L1=0.3Lc. (4)

Sk=Dw - ε 2, (5)

ε Take 0.15 to 0.25 for 2.

Sk1=Dw+0.5. (6)

2.3 Determination of outer lock diameter in outer lock state

When Dcp<Dpw, the cage is in an externally locked state, and the diameter of the external lock is its outer diameter Dc. As shown in Figure 2, in the horizontal direction, the distance from the midpoint of the chord length Sk of the cylindrical roller to the axis of rotation of the bearing is R'c. According to the geometric relationship in Figure 2

When in the external locking state, the outer diameter Dc of the cage is (with an accuracy of 0.01 mm)

The Dc tolerance is comprehensively considered based on the tolerance of the roller, outer ring raceway, and the gap requirements between the roller and the cage and raceway.

Figure 2 Geometric Relationship Diagram in External Lock State

2.4 Determination of Inner Lock Diameter in Inner Lock State

When Dcp>Dpw, the cage is in an internal locking state, and the internal locking diameter is its inner diameter dc. As shown in Figure 3, in the horizontal direction, the distance from the midpoint of the chord length Sk of the cylindrical roller to the axis of rotation of the bearing is r'c. According to the geometric relationship shown in Figure 3

When in the locked state, the inner diameter dc of the cage is (with an accuracy of 0.01 mm)

The DC tolerance is comprehensively considered based on the tolerance of the roller, inner race raceway, and the gap requirements between the roller and the cage and raceway.

2024 March 3th Week KYOCM Product Recommendation:

Thrust Ball Bearing:

Thrust ball bearings are designed to take axial (thrust) loads at high speeds, but they cannot take any radial loads. These bearings feature bearing washers with raceway grooves in which the balls move.

Thrust ball bearings are classified into “flat seat” and “aligning seat” types, based on the shape of the housing washer (outer ring seat), and as single-direction or double-direction. Spherical and aligning seat washers help to provide tolerance for mounting errors.

Figure 3 Geometric relationship diagram in locked state

3. Conclusion

Based on the geometric relationship between the inner and outer locking states of the cylindrical roller bearing O-ring cage, theoretical calculation formulas for the inner and outer locking diameters of the cage were derived, solving the problem of determining based on experience in design.