High-Performance Combing
The new E 65/E 75 (ROBOlap) generation of combers from Switzerland-based Rieter Textile Systems has made it technically and technologically possible to achieve nip rates of 450 per minute in cotton combing.
Textile World Asia Special Report
S
witzerland-based Rieter Textile Systems recently introduced the E 65/E 75 (ROBOlap)
generation of combers to the spinning market. The machines feature new and upgraded technologies
designed to enhance operation and final product quality.
Figure 1
Performance Boost Through C A P D+
Rieter’s own Computer-Aided Process Development (CAPD) program, based on in-house technology, already was used in the development of the E 62/E 72 predecessor models. This program enabled the batch combing process to be made operationally reliable in technological terms in mill operations, offering controlled detachment and layering, as well as piecing of the detached and combed fiber packages, even at higher nip rates. This provided a sound basis for the E 65/E 75 machine generation. By adopting proven elements and incorporating other optimization features, the nip rate has been increased to 450 per minute in the short- and medium-staple range by means of CAPD+. Combing in the long-staple range (greater than 1 inch) also is performed in most cases at nip rates of 400 to 420 per minute.
Circular Comb And Top Comb: Basic Modules For Precise Fiber Selection
The Primacomb 8014 and 8015 circular combs specially developed for the E 65/E 75 generation machines ensure gentle, controlled fiber tuft intake and thus optimum combing action in conjunction with the motion of the circular comb and the high-precision clamping of the nippers. Key aspects are the optimized front angle, the lengths of the tooth row segments with corresponding gap widths, and the configuration of the clothing points.
Rieter’s new Ri-Q-Top top combs offer superior combing efficiency and have a low tendency to soil because of a new point shape and modified tooth cross section. For example, short fibers that have been carried along — such as floating and unguided short fibers — are stopped by the top comb during detaching; and the new tooth cross section prevents accumulation at the tooth base. Instead, these fibers are disposed of in the next circular combing cycle. This results in a reduced tendency to soiling and improved combed sliver consistency, compared to needled top combs.
New Drafting System Improves Sliver Quality
The slivers from the eight separate combing heads are now fed to a three-over-three-cylinder drafting system (See Figure 1). Synergies with proven Rieter drafting technology have been exploited in particular in geometry and subsequent web formation. In combination with variable main and break draft distances, all staple lengths can be processed further on the autoleveler drawframe while attaining superior CVm values with simultaneously adequate sliver adhesion length. The main draft peaks occurring in the spectrogram with the earlier three-over-five-cylinder drafting systems, resulting from floating fibers, are a thing of the past thanks to precision drafting action in the two drafting zones.
The band widths of the mass diagrams and the CVm value are thus decisively improved. The piecing stack characteristic of the comber does not change because of the system, but is more clearly apparent in the spectrogram (See Figure 2) because of the lower main draft peak. However, this is an advantage on the autoleveler drawframe, because this long-wave fault is clearly registered by the control system and is subsequently leveled out reliably.
The slivers from the eight separate combing heads are now fed to a three-over-three-cylinder drafting system (See Figure 1). Synergies with proven Rieter drafting technology have been exploited in particular in geometry and subsequent web formation. In combination with variable main and break draft distances, all staple lengths can be processed further on the autoleveler drawframe while attaining superior CVm values with simultaneously adequate sliver adhesion length. The main draft peaks occurring in the spectrogram with the earlier three-over-five-cylinder drafting systems, resulting from floating fibers, are a thing of the past thanks to precision drafting action in the two drafting zones.
The band widths of the mass diagrams and the CVm value are thus decisively improved. The piecing stack characteristic of the comber does not change because of the system, but is more clearly apparent in the spectrogram (See Figure 2) because of the lower main draft peak. However, this is an advantage on the autoleveler drawframe, because this long-wave fault is clearly registered by the control system and is subsequently leveled out reliably.
High-Performance Combing Versus Yarn Quality
Gentle and rapid combing results in a further reduction in the dwell time of fibers in the circular comb clothing compared with earlier combing methods. The yarns produced therefore display no impairment of stress-strain behavior because over-elongation of the fibers is prevented. On the other hand, the IPI level of the yarns can be maintained and, in most cases, even improved by high-frequency combing compared with lower nip rates (See Figure 3). To complete the circle, the inevitable, infrequent weak places in the yarn, which are especially disturbing in downstream processing, are now mostly located at a higher stress-strain level than in production at lower nip rates. Comparisons of single-jersey knits have also shown that those made from yarns combed on the E 65 turn out more uniformly than those of the preceding generation. The new drafting system plays a major role in this.
In developing the E 65/E 75 combers, Rieter also focused on defined quality in the yarn and the final fabric — an essential factor in fulfilling the responsibility to customers as a systems supplier.
November/December 2006
Gentle and rapid combing results in a further reduction in the dwell time of fibers in the circular comb clothing compared with earlier combing methods. The yarns produced therefore display no impairment of stress-strain behavior because over-elongation of the fibers is prevented. On the other hand, the IPI level of the yarns can be maintained and, in most cases, even improved by high-frequency combing compared with lower nip rates (See Figure 3). To complete the circle, the inevitable, infrequent weak places in the yarn, which are especially disturbing in downstream processing, are now mostly located at a higher stress-strain level than in production at lower nip rates. Comparisons of single-jersey knits have also shown that those made from yarns combed on the E 65 turn out more uniformly than those of the preceding generation. The new drafting system plays a major role in this.
In developing the E 65/E 75 combers, Rieter also focused on defined quality in the yarn and the final fabric — an essential factor in fulfilling the responsibility to customers as a systems supplier.
November/December 2006
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