Rieter

The spindle bearing

Index

Fig. 19 – Vibration absorber (10) in a spindle bearing

Fig. 20 – Spindle damping function: a, spiral spring; b, spindle blade; c, oil flow

The design of a modern spindle bearing is briefly explained here on the basis of the Texparts CS1 spindle (Fig. 19). The spindle bearing consists of 2 parts, a spindle collar bearing (1) and a spindle step bearing (3). Both parts are connected via housing (7). The spindle collar comprises a precision roller bearing. The spindle step, designed as a friction bearing (conical bearing), is responsible for the elastic centering and cushioning of the spindle center shaft. Two centering and cushioning elements (6) control the bearing shaft (2). An oil-filled spiral (10) mounted symmetrically with the spindle step ensures optimum cushioning. Spindle step (3) also absorbs all vertical forces acting on the spindle.
The spindle collar can be a friction bearing or a roller bearing. The noise level can be reduced considerably by using friction bearings, but energy consumption is somewhat higher. Most spindles are therefore equipped with roller bearings. The spindle collar is rigidly friction-set in the bearing housing in standard spindles. Bearing vibration is therefore transmitted to the spindle frame without damping. This results in high noise levels at higher speeds. For speeds over 18 000 rpm, spindles are therefore mostly used in which not only the spindle step, but also the spindle collar is attached flexibly to the bearing housing (e.g. Novibra HP-S 68). These spindles are more expensive, but permit higher speeds and reduce noise levels in ring spinning machines by some 10 dB (a) compared with standard spindles.

Spindle step (3) is always a friction bearing and flexible, i.e. it can tilt sideways to a small extent. The spindle is therefore able to center itself, which enables it to operate in hypercritical ranges. This results in a significant reduction in bearing forces. High-performance spindles are inconceivable without damping devices (10). Various systems are used, such as damping spirals, damping tubes or damping oil around a steel tube.

If damping spirals are used, spiral spring (a) is compressed at one side when the spindle is deflected to side (b) (Fig. 20). The oil therefore flows from this side to the other side, where the gaps become wider (c). The resistance the oil has to overcome in the process damps the vibration in the spindle step and ultimately in the shaft.

The cavity between the spindle blade and the bearing housing is largely filled with lubricating oil. Since the oil is used up, it has to be replenished from time to time. This is necessary after about 10 000 - 25 000 operating hours.