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Rolling guides www.mapeng.net 马棚网机械资讯
Rolling linear guides and guide-ways are widely used in practice, alongside plain linear guides. The following advantages are obtained when compared with plain guides: light running forces due to rolling friction, no stick-slip, trouble-free installation and immediate availability due to standardization of the rolling elements. www.mapeng.net 马棚网机械资讯
The main disadvantage of this type of guide when compared with hydrostatic and hydrodynamic guides lies in the low dam effects in the direction normal to the movement. www.mapeng.net 马棚网机械资讯
Figure 1 shows in its upper section a rolling guide using a roller chain. Generally, rolling elements travel half the distance moved by the slide. When roller chains are employed, their length must at least equal the sum of half the slide travel plus its own length. Hence, for long movements rolling guide ways in general employ recirculating roller elements, as shown in the lower half of Fig. 1. In this case the rollers run in an endless track so that the movement is limited only by the length of the running surface. www.mapeng.net 马棚网机械资讯
For accurate operation of the complete rolling guide way, consideration must not only be given to the quality of both guiding surfaces but also to the dimensional and geometric accuracy of the rolling elements and their control in the cage. When cylindrical rollers are used, inaccurate cages as well as non-parallel guide way surfaces can lead to angular motion and side thrust of the rollers on the cage, which in turn will result in damage to the guiding surfaces and the cage itself, due to the friction generated. This problem is not encountered when balls are used as rolling elements, but such guides have the disadvantage of even lower stiffness and load-carrying capacity when compared with roller linear guides (point contact instead of line contact). www.mapeng.net 马棚网机械资讯
Rolling-contact bearings. Ball bearings. Figure 2(top) Shows two views of www.mapeng.net 马棚网机械资讯
one quarter of the most widely used type of modem bail bearing. It consists of four parts: an inner race b, an outer race c, the balls d, and a separator or retainer e, which is also called a cage. www.mapeng.net 马棚网机械资讯
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Fig. 1 Principles of construction for linear roller guideswww.mapeng.net 马棚网机械资讯
The races in which the balls roll have grooves with radii of curvature slightly greater than the radius of a ball. Some bearings are assembled by moving the inner race radially, inserting the balls, centering the inner race, spacing the bails uniformly, and applying the retainer that holds the balls loosely in an equally spaced position. Other bearings have a notch in one of the races that permits more balls to be inserted. With more balls, the bearing can carry more radial load R (Figure 2[top]), but less thrust load T on account of the notch. www.mapeng.net 马棚网机械资讯
Although the bearing in Figure 2 (top) is classified as a radial ball bearing, ft has considerable thrust or axial-load capacity. The thrust capacity T can be increased by extending the races to sections ff so that the groove in the outer race is deeper on the left side and the groove in the inner ra
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