Abstract
A rolling bearing, wherein the rolling elements are loaded, equipped with a cage separating the rolling elements, wherein at least one groove is situated on the bearing race on which the rolling elements travel, wherein edges of the groove are positioned at an angle α from 4.5° to 80° in relation to the movement direction of the rolling elements, and in the cage, holes for the rolling elements are made askew so that the angle β between a straight line connecting the cage centre with the centre of the hole for the rolling element and a tangent to the rolling element in the contact point of this element with the cage has a value β>arc tg μ, where μ is the sliding friction coefficient of mating of the rolling element material with the cage material.
Claims
1. A rolling bearing comprising rolling elements, wherein the rolling elements are loaded, equipped with a cage separating the rolling elements, wherein at least one groove is situated on a bearing race on which the rolling elements travel, wherein edges of the at least one groove (4) are positioned at an angle α from 4.5° to 80° in relation to the movement direction of the rolling elements (3), and in the cage (7), holes for the rolling elements are made askew so that an angle β between a straight line connecting a center of the cage O1 with a center O2 of the rolling element (3) and a radially extending tangent (8) to the rolling element (3) at a contact point of the rolling element with a wall of the hole of the cage which delimits a length of the hole in a circumferential direction has a value β>arc tg μ, where μ is the sliding friction coefficient of mating of the rolling element material (3) with the cage material (7).
2. A rolling bearing according to claim 1, wherein the groove (4) is positioned so that the rolling element would move towards a greater diameter of the bearing race.
3. A rolling bearing according to claim 1, wherein for the bearing rotating in one direction, radially extending tangents to the rolling element (3) at a contact point of the rolling element with a wall of the hole of the cage which delimits a length of the hole in the circumferential direction are parallel.
4. A rolling bearing according to claim 1, wherein for the bearing rotating in both directions, a radially extending tangent to the rolling element (3) at a contact point of the rolling element with a walls of the hole of the cage which delimits a length of the hole in the circumferential direction are convergent.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
(1) The subject of the invention is illustrated in the drawing, wherein
(2) FIG. 1 shows a cross-section of an ordinary ball bearing with a cage;
(3) FIG. 2a and FIG. 2b show a cross-section of an embodiment of the groove in the right and left direction in relation to the movement direction of the rolling element on the bearing races;
(4) FIG. 3a and FIG. 3b show the shift of the rolling element towards the larger diameter;
(5) FIG. 4a, FIG. 4b, FIG. 5a, FIG. 5b, FIG. 6, FIG. 7a and FIG. 7b show a cage fragment and forces exerted by the cage onto the rolling elements, and
(6) FIG. 8 shows an example of a bearing arrangement on two bearings with right grooves.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
(7) An embodiment of the bearing according to the invention shown in FIG. 1 is a single-row ball bearing. The bearing consists of an outer ring 1, an inner ring 2, rolling elements having the form of balls 3, and a cage 7. The rolling elements roll on an external bearing race 5 and an internal bearing race 6. A skew groove 4 is made in the internal bearing race 6. The groove 4 is situated askew in relation to the movement of the rolling elements 3, and the movement is marked with an arrow in FIG. 2a and FIG. 2b. While entering the groove 4 area, the rolling element 3 temporarily unmates off the races 5 and 6, and shifts, because of the taper of the groove 4, towards the larger diameter bearing races, from the diameter d1 to the diameter d2, as shown in FIG. 3a and FIG. 3b. It allows for gentle starting of the mating with both races 5 and 6 while the rolling element 3 is leaving the groove 4.
(8) As shown in FIGS. 4a through 7b, the rolling elements 3 are placed in the cage 7 in holes made askew, and the taper inclination angle β between a straight line O.sub.1O.sub.2 connecting the centre O.sub.1 of the cage 7 with the centre O.sub.2 of the hole for the rolling element 3, and a radially extending tangent 8 to the rolling element 3 at the contact point of this element with one of the walls of the hole of the cage 7 which delimits the length of the hole in the circumferential direction has a value β>arc tg μ, where μ is the friction coefficient of mating of the rolling element material 3 with the cage 7.
(9) As shown in FIG. 4a, at the cage 7 being guided on the internal ring 2 rotating with a rotational speed n.sub.r, a force lifting the cage 7 upwards, Fl=Fs sin β, emerges at the point of contact between the cage 7 and the rolling element 3. The aim of this force is to reduce the impact of the cage 7 on the bearing's ring guiding the cage 7. This force must be larger than the force Ft=Fn μ, being the force of friction between the rolling element 3 rotating with a rotational speed n.sub.b and the cage 7, in the point of contact of these elements, where Fn=Fe cos β; Fe is the force exerted by the cage 7 onto the rolling element 3; μ is the sliding friction coefficient of mating of the cage 7 material and the rolling element 3 material. A condition of β>arc tg μ results from these equations. In the case when the cage 7 jest is made of polyether etherketone (PEEK), and the rolling elements are made of 100Cr6 steel, the sliding friction coefficient between these materials amounts to μ=0.4. Then, in accordance with the β>arc tg μ formula, the taper inclination angle of the cage should be β>22°.
(10) FIG. 4b shows a distribution of forces, when the instantaneous angular velocity of the cage 7 is faster than the angular velocity of the rolling element 3.
(11) FIG. 5a and FIG. 5b show a distribution of forces between the cage 7 and the rolling element 3 in the case of rotation of the bearing's inner ring 2 in both directions.
(12) FIG. 6 shows a distribution of forces between the cage 7 and the rolling element 3 in the case of guiding of the cage 7 on the external ring 1, with the internal ring 2 rotating with a rotational speed n.sub.r.
(13) FIG. 7a and FIG. 7b show a distribution of forces between the cage 7 and the rolling element 3 in the case of guiding of the cage 7 on the external ring 1, with the internal ring 2 rotating in both directions with a rotational speed n.sub.r.
(14) In FIG. 8, an example of a bearing arrangement on two bearings with right grooves 4 is shown. Directions of the grooves 4 in relation to the rolling elements 3 moving on the bearing race yield a more preferable distribution of forces between the rolling element 3 and the races while passing through groove 4. To obtain a preload of the bearings with the force Fs, a spring 9 is used. Fa is the external load of the bearing with the longitudinal force.
