Paper 4: Opening,Carding and Spinning Preparation Machines

There are no serious bearing problems in opening and carding machines. Except for the high-speed beaters and cylinders, occasionally-oiled plain journals were long regarded as adequate despite the fact that many of them operated under boundary lubrication conditions. Stable hydrodynamic film conditions were maintained in beater and cylinder bearings and some simple form of lubricant reservoir was usually provided. In recent years the introduction of shift working and high machine utilization factors have led to a demand for machines requiring a minimum of attention. This demand is being met by the use of prepacked, sealed ball or roller bearings at all points.

Perhaps the most serious and intractable bearing problem in the whole field of textile machinery manufacture is encountered in drawframes and speedframes. For uniformity of the drawing action by which the fibres are straightened and finally attenuated to form a roving, it is necessary for all the drafting rollers to rotate perfectly smoothly. Unfortunately the loading conditions and the rotational speeds of some of the rollers are such that there is often a high liability to the occurrence of spontaneous stick–slip torsional vibrations. In other cases there is an incipient liability to stick–slip vibration and quite small gearing faults, of the appropriate frequency, are sufficient to precipitate high amplitude oscillations.

At the frequencies commonly observed the non-uniformity of the drawing action introduces into the sliver or roving a periodic disturbance of a wavelength so short that it is not readily apparent in the delivery from the affected machine. Subsequent drafting, however, increases the wavelength and the ultimate yarn exhibits appreciable variations in mass per unit length and in twist distribution. As these variations are strictly periodic they form objectionable interference patterns when used as weft in either woven or knitted cloths. New machine designs and the use of new types of bearings have largely solved these problems and at the same time greatly increased operating speeds.

The comber, too, has been intensively developed during the past ten years and a number of lubrication and wear problems have required attention.