Needle roller bearing with double row of retainers

Abstract

A retainer-equipped double-row needle-roller bearing includes a pair of annular end flange portions; a center annular center flange portion; and two rows of pillars connecting the portions to each other to provide pockets between mutually adjacent pairs of pillars in a circumferential direction for holding rollers in two rows. The center flange portion has an outer diameter (D2), and the end flange portions have an outer diameter (D1), in a relationship expressed as D2<D1. When the retainer moves radially by an amount of gap associated with the rollers, the retainer is guided on the outer diameter surfaces of the end flange portions at two ends of the retainer, by the inner diameter surface of a housing. This stabilizes behavior of the retainer during rotation, reducing premature wear and abnormal noise.

Claims

1. A retainer-equipped double-row needle-roller bearing comprising: a retainer designed to be guided on an outer diameter of the retainer, the retainer including: a pair of annular end flange portions; an annular center flange portion; and two rows of pillars connecting said pair of end flange portions and said center flange portion to each other, and the end flange portions, the center flange portion, and the pillars form a single member in a thickness direction and in an axial direction and are heat treated; and a plurality of rollers held in the pockets of the retainer, wherein the center flange portion is made to have a thickness T2 smaller than a thickness T1 of each end flange portion of the pair of end flange portions at two ends and the center flange portion and the pair of end flange portions are made to have a greater thickness than a thickness of the pillars in a radial direction, thereby the radial thickness of the retainer is made unequal in its axial direction, and the center flange portion has an outer diameter (D2), each end flange portion of the pair of end flange portions has an outer diameter (D1), and the outer diameter (D2) of the center flange portion and the outer diameter (D1) of each end flange portion are made to have a relationship of D2<D1.

2. The retainer-equipped double-row needle-roller bearing according to claim 1, wherein the thickness T2 of the center flange portion and the thickness T1 of each end flange portion of the pair of end flange portions at the two ends have a relationship of T20.80T1.

Description

BRIEF DESCRIPTION OF DRAWINGS

(1) FIG. 1 is a perspective view of a double-row needle-roller bearing with retainer according to the present invention.

(2) FIG. 2 is a sectional view of the retainer according to the present invention in FIG. 1.

(3) FIG. 3 is a sectional view showing a state that a retainer according to the present invention which was deformed due to heat treatment is moved radially.

(4) FIG. 4 is a perspective view of a conventional double-row needle-roller bearing with retainer.

(5) FIG. 5 is a sectional view of a retainer of the conventional double-row needle-roller bearing with retainer in FIG. 4.

(6) FIG. 6 is a sectional view showing a state that the conventional retainer which was deformed due to heat treatment is moved radially.

DESCRIPTION OF EMBODIMENTS

(7) Hereinafter, embodiments of the present invention will be described based on the attached drawings.

(8) As shown in FIG. 1, a retainer-equipped double-row needle-roller bearing 1 according to an embodiment of the present invention includes two rows of rollers 2 held by a retainer 3. The retainer 3 has a pair of annular end flange portions 3a, 3a; a center annular flange portion 3b in the middle; and two rows of pillars 3c, 3c connecting these portions to each other. Each pair of the pillars 3c which are mutually adjacent in a circumferential direction provide a pocket for holding one of the rollers 2. The retainer 3 is guided on its outer diameter or outer/inner diameters.

(9) In the present invention, in the retainer 3 of a double-row type, the center flange portion 3b which has an outer diameter (D2) and the end flange portions 3a which have an outer diameter (D1) have a relationship expressed as D2<D1. In other words, the outer diameter (D2) of the center flange portion 3b is smaller than the outer diameter (D1) of the end flange portions 3a.

(10) In order to achieve the relationship D2<D1, as shown in FIG. 2, the center flange portion 3b is made to have a smaller thickness T2 than a thickness T1 of the two end flange portions 3a by appropriate means. In order to make the thickness smaller, coining may be performed to retainer material to reduce the thickness of the center flange portion, or material in the center flange portion may be partially removed mechanically by grinding or the like.

(11) The outer diameter (D2) of the center flange portion 3b in the retainer 3 is slightly smaller than the outer diameter (D1) of the end flange portion 3a. If too small, the retainer 3 will have a reduced rigidity, leading to fracture of the retainer 3. Therefore, it is necessary to select a value which will not allow the outer diameter (D2) of the center flange portion 3b to become greater than the outer diameter (D1) of the end flange portion 3a even in the deformed state. Preferably, the value is T20.8T1, and more preferably, T20.9T1.

(12) The retainer 3 according to the present invention has the outer diameter (D2) of the center flange portion 3b and the outer diameter (D1) of the end flange portions 3a in the retainer 3 being in the relationship expressed as D2<D1. This stabilizes rotation behavior of the retainer 3, as indicated by an arrow in FIG. 3, since the outer diameter surface of the end flange portions 3a at two ends of the retainer 3 are guided by the inner diameter surface of the housing 4 when the retainer 3 moves radially by an amount of gap associated with the rollers 2, reducing premature wear and abnormal noise.

(13) The retainer 3 may be heat treated and then be utilized after the heat treatment without performing grinding on its outer diameter.

(14) The retainer 3 may be formed by grinding or pressing.

(15) Also, the retainer 3 may be made by rolling and welding a steel plate.

(16) Also, the retainer 3 may be made by cutting and grinding a steel ingot, or by injection molding of a resin.

REFERENCE SIGNS LIST

(17) 1 Bearing 3 Retainer 3a End flange portion 3b Center flange portion 3c Pillar 4 Housing T1 Thickness T2 Thickness