Introduction: polished rod - Ball bearing transmission principle - bearing knowledge

The polished rod - Ball bearing drive mechanism of the structure is very simple, only by the polished rod, nut and four respectively of tilt centripetal ball bearings ( See figure 2) 。 The accuracy of ball bearing level just regular grade; Inside circle aperture is ground into a symmetrical two conical surface, cone busbar with the center line of the bearing on the Angle and nut and bearing outer ring with inner hole of the tilt is consistent, are 9 °; Four bearing respectively on it, below the disc spring pressure on the single direction. The structure adopts 6007 type bearing FAG company in Italy, the overall dimensions for the 35 x phi phi 62 x 10 mm, with our country's seven o001o7 ( φ35 xφ62×9毫米) And 107 ( φ35×φ62×14毫米) Similar. Outer diameter of the polished rod is 34 mm, after tempering treatment. As a result of disc spring unidirectional power works, the middle two next to the upper half of the bearing inner ring and the bottom half of bearing inner ring respectively contact with polished rod, and the other half of them don't contact with the surface of the polished rod. Because of the polished rod diameter ( As the phi 34 mm) Smaller than the bearing inner diameter ( φ35mm) When the servo motor rotating the polished rod, if you don't consider skid, the influence of such factors as inner cone bearing inner ring borrow and polished rod friction, to scroll on the polished rod, the polished rod turn every week bearing with a nut produce axial displacement S distance, and S = PI Dtg9 ° = PI * tg9 34 ° = 16. 92 mm, very close to the actual feeding ( 16mm) 。 Due to the nut drive the dragging plate, so that the rotation of the polished rod motion into the linear motion of the carriage. Without applying single disc spring the direction of the force to the ball bearing, the rotation of the polished rod can only cause bearing inner ring relative to the rotation of the outer ring, to make the nut of the axial displacement. When polished rod for a positive direction, in the middle of two bearings B surface can be driven nut c2: right, and on both sides of the bearings do not work; If polished rod to rotate in the opposite direction, the two bearings on the edge of A surface can be driven nut move to the left, and in the middle of the bearing does not work. So as the change of polished rod rotation direction, can be for different directions of dragging plate movement. Using the results of the four bearings, not only increased the carrying capacity, and make the institutions to receive strength evenly and smooth movement. The polished rod - Ball bearing drive structure is very simple, so the price is only a small percentage of the ball screw pair. Its transmission effect is quite good, even if 2 ~ 3 people standing on the apron, twisted with the hand polished rod, no trouble to make the dragging plate for linear motion. Another advantage of this structure is a very good ability to overload protection. When dragging plate or nut are blocked and could not move, if polished rod to rotate the bearing for relative rotation between the inner and outer circle, only protect institutions from damage. Because may not produce a pure roll, the main drawback of this structure is precise linear feeding is difficult to guarantee, so the general can only be used for loading small and feeding requirements is not very accurate. But if you have any position on the dragging plate configuration detection system, it is still more force. Currently abroad has a widespread adoption of this kind of simple transmission mechanism to replace part of the ball screw pair.