The Rupp Report: Breaking Boundaries
Jürg Rupp, Executive Editor
The combing machine is a key factor determining yarn quality in the spinning process. After the draw frame process, there is no possibility to further increase the quality of the yarns to be produced. With this combing process, the fibers become high-quality yarns. A superior and uniform quality with reduced noil extraction can be achieved, which results in top-class yarns with added value. A high and even quality is determined by combing movements and the batt weight.
Traditional combing machines have been working for decades more or less according to the same principle. The driving or so-called "pilgrim" step movement is the most complex back-step movement of the detaching rollers. The requirement of rotational reversal sets boundaries. The collaboration between Toyota and Trützschler has led to a completely new comber concept: the new TCO 12 comber has a different approach and delivers results that virtually have never been achieved before. With this very new type of combing machine, one can say it is truly quite different from any other model on the market.
The Conventional Concept
In conventional combers, the mono drive for the thin detaching rollers produces strong torsions. As a result, vibrations and deviations in combing quality and noil volume occur between the comb heads. The detaching rollers' one-sided drive and the associated rotation reversal at each nip causes strong torsional forces. The farther the combing heads are from the gear box, the more strongly the thin axles start to distort, and, moreover, they start to swing.
This situation inevitably leads to different combing qualities by each of the eight combing heads. The amount of combing noils and the reduction of short fibers varies considerably. Therefore, the overall performance of the comber is also limited.
Weaving Machine Technology
The new concept of the Toyota-Trützschler Comber TCO 12 is based on two-times-two highly dynamic synchronous servo motors, which replace the unilateral transmission. There are no cams or elliptical gears in an oil bath gear to drive the comber. Two fully synchronized motors on each side — four motors in all — drive the two detaching rollers. According to the manufacturers, this design results in synchronous running and absolutely comparable motion sequences on all comb heads. By using individual drives, the motion sequence can be precisely determined by the machine control. Thus, for the first time, an application-oriented optimization of the piecing process is said to be possible. This layout is based on Toyota's weaving machine technology and is designed to provide maximum dynamics and frequency of rotation. With this concept, the twists are reduced by 75 percent. Every machine designer is always fighting against vibrations caused by the machine drive. With the servo drives on each side, the vibration is reduced to less than 25 percent.
Latest Drafting Technology
It seems that for the first time, a combing machine is equipped with a full-fledged draw frame. This system is called Count Control, referring to the fact that the main target of the draw frame is to maintain a constant sliver count on the comber. The four-over-three drafting system with pressure bar and its drafting system geometry has been successfully applied in drafting of comber slivers using leveler draw frames. The same-quality sensors, called Disc Monitor, are used in the Trützschler draw frames. Both companies are convinced that such an even quality of the sliver has been achieved for the first time using this new machine.
The fourth top roller ensures an even gentler sliver deflection at the delivery side of the drafting system, while the adjustable pressure bar in the main draft area provides controlled guidance. When adjusting the drafting zone widths, the top rollers are guided in the bearing blocks of the bottom rollers. This process is said to ensure 100-percent axis parallelism for optimal control of the fiber flow and results in a sliver evenness that has not been possible with existing combing machines. The Disc Monitor is responsible for a consistent sliver count and optimized sliver geometry.
Tests reflect the outcome of the new TCO 12: The Uster coefficient of variation (CV) value is considerably below 3 percent, which corresponds to a uniformity (U%) value of 2.28. The 1m CV value is even lower than level 1 and the 5m value is 0.23. All these values were achieved with a speed of 600 nips per minute.
Where Is The End?
Some experts will always predict that age-old spinning technology is at the end of its evolution. When rotor spinning came onto the market, ring spinning was predicted to be out of the market soon. Wrong. When the air-jet spinning technology became feasible, rotor spinning was predicted to be outdated soon. Wrong. The same experts declared that along the spinning process, there is no possibility to design a considerable improvement of the process, whether in speed or quality. Wrong. The collaboration between Toyota and Trützschler shows a different approach and the will to think in a different way: Combined expertise can result in uncommon products. There should be much more to say about the new machine. Time will tell if the idea is successful on the market.
November 27, 2012