Rieter

Operating principle

Index

Extensive investigations have been made and testing has been performed by Goetzfried and Lord. However, the process was brought to industrial maturity by the Polish Wifama- Polmatex company. Several machines of this type are or have been in experimental use in Poland. However, this spinning system never achieved real industrial success. In this spinning method (Fig. 3), yarn is formed by an air vortex in a tube (1). For this purpose, air is sucked by a vacuum source (6) into the tube through tangential slots (2). This incoming air moves upward along the tube wall in a spiral and finally arrives at the upper tube seal (3). Since the top of the tube is closed by the seal (3), the air then flows to the center of the tube and moves down again to the vacuum source. Thus an air vortex (5), rotating continuously in the same direction, is generated at the seal (3).
Opened fiber material is allowed to enter the system through a tangential opening (4). The rising air stream grasps this material and transports it upward into the vortex (5). To form a yarn, an open yarn end is passed into the tube through a passage in the upper seal (3). The vortex grasps this yarn end and whirls it around in circles in the same way as the fibers. Since the upper yarn length is held by the withdrawal rollers and the lower end is rotating, each revolution of the yarn end in the vortex inserts a turn of twist into the yarn.
Formation of the fiber strand itself arises because the rotating open yarn end in the vortex is presented with a multiplicity of floating, rotating fibers, which are caught by the bound-in fibers of the yarn end and are thus continuously twisted in.
One associated problem is maintaining good fiber configuration and achieving correct, ordered binding-in of the fibers, i.e. achieving adequate strength in the yarn. For this reason, synthetic fibers of the highest attainable uniformity were mainly used. A second deficiency is variability in the degree of twist in the spun yarn. In fact, the rotation speed of the fiber ring in the vortex (5) is not constant, due to mass variations in this fiber ring. Hence, the imparted yarn twist also varies as a function of time. On the other hand, a major advantage of the process is the absence of any kind of rapidly rotating machine parts.

Fig. 3 – The air-vortex spinning principle