Rieter

Correction rail (compensation rail, correction rod)

Index

Fig. 22 – Functional diagram of the correction rail

If the movement of the belt does not correspond to the increase in bobbin diameter, the change wheel or ratchet must be adjusted accordingly. Sometimes, however, the adjustment resulting from changing by one tooth would have an over-large effect; a change by only half a tooth might in fact be suitable. In order to deal with such borderline cases, i.e. to provide a degree of fine setting, several roving frames are now fitted with a correction rail (Fig. 22). This is a rail (1) which is mounted in the region of the belt guide (not shown) and in its normal position is parallel to that guide. At position 4, however, the rail can be shifted to bring it into another position relative to the belt guide. A roller runs on the correction rail. The belt shifting rope is guided around this roller and is secured to the belt guide at 5.

If the rail and belt guide are not parallel, i.e. if the correcting rail has a greater inclination than the belt guide as shown in the illustration (2), the roller (dotted lines) moves further upward (3), away from belt guide (5). The distance between roller (2) and the anchoring point of the rope increases from A1 to A2. This means that the extension of the rope as determined by the builder motion is not transferred completely to the belt guide; instead, part of that extension is taken up in increasing distance A from A1 to A2. Shifting of the belt takes place through smaller steps than those corresponding directly to the paying out of the rope in the builder motion. The reverse effect is obtained if the correction rail is offset in the other direction relative to the belt guide. The increase in diameter of the bobbin is in principle a linear function of the number of layers. This relationship may not hold true in practice, because the winding conditions do not remain absolutely constant. At the start of a winding operation, roving is wound onto a hard core (bobbin tube); toward the end of the winding operation the receiving body may be softer – depending on the compactness of the roving – since the material itself now provides that body. This change, and also other changes in associated conditions, can give rise to tension variations during winding. In order to be able to adapt to these, the correction rail is often made in several parts, which are adjustable relative to each other. In this way, any desired tension level can be set from beginning to end of the winding operation by relative raising or lowering of the individual rail sections.