The influence of increasing the productivity of the carding machine on the quality indicators of the card sliver

. (cid:3) The paper investigated the influence of the rotation frequency of the take-up, main and doffing drums of the C60 carding machine from RIETER on the quality indicators of the card sliver. The raw material used was medium-fiber cotton with a fiber length of 26.5-28 mm. The experimental study was carried out with changing speed modes: rotation frequency of the main drum from 451 to 520 rpm, of the take-up drum from 1018 to 1400 rpm, of the doffing drum from 62 up to 72 rpm.The quality indicators of the produced card sliver were determined using an USTERTESTER-5 laboratory equipment. It was established that an increase in the speed mode of the main working bodies within the studied limits on carding machines does not cause a deterioration in the combing quality.


Introduction
Machines in the opening-and-lap forming workshop of spinning production separate up to 70% of impurities and fiber defects from processed cotton.The remaining impurities and fiber defects (1÷8.0%by weight of the fabric) are located both on the surface and inside the fiber scraps that form the fabric or flow entering the carding machines.Therefore, further effective cleaning of the fibrous material is only possible by separating the fiber scraps into individual fibers.This is carried out during the carding process, as repeating the scutching process does not give the desired result, since the organs of the scutching machines are not adapted to separate the bundles into individual fibers [1][2][3].
Thus, the main purpose of the carding process is to separate fiber bundles into individual fibers and clean the latter from impurities and defects.The carding process becomes particularly important in a card spinning system, where the carding machine is the last machine on which the fibrous material is cleaned [4,5].
Only from well-combed fibers and a clean and uniform card sliver it is possible to obtain clean and even yarn, which is largely determined by the design of the carding machine [6].
Since 1965, productivity has increased from approximately 5 kg/h to 180 kg/h [7].Modern carding machines are very complex with many functions, regulation sensors, monitoring of neps, microprocessor-controlled operations, servomotor settings, integrated grinding systems (IGS) from Rieter [8], triple take-up drum, fixed flat segments, with increased carding area and automatic waste collection, suction points for lint extraction and easy-to-maintain machine design.
Today, to achieve the best production and quality of the supplied material, it is necessary to optimize the speed parameters of the carding machine, such as the speed of the take-up drum, main drum, flats and doffing drum.Changing the quality parameters of the card sliver leads to failures in subsequent processes; drafting, pre-spinning and spinning [9][10][11].
Numerous studies were carried out to study the carding machine performance in improving yarn properties.In a study [12] on the effect of release speed on yarn quality, it was observed that the change in carding release speed does not show a significant effect on the change in the coefficient of variation by yarn number, yarn unevenness, yarn elongation and yarn hairiness index.While, the defects of IPI yarns increases, the strength of single yarns decreases when the release speed is increased.In practice, it was also observed that in order to meet the demand of high production with good quality yarn, spinners always try to optimize both the carding speed and the yarn quality.
Research work [13] was carried out to achieve optimization of the appropriate carding machine flat speed for production of cotton carded yarn and evaluate the quality of the final products.The study determined that carded yarn produced at high flat speeds provides the best quality.The content of short fibers and neps in the card sliver at the highest flat speeds is lower than at other speeds.This is due to the difference in the flat speed, which leads to improved carding performance.Analyzing the main quality indicators of yarn, this study suggests that yarn with good quality in the spinning process can be achieved through higher flat speed.
In [14], the study focused on the production of 20 tex compact yarn from four different 100% cotton blends (American cotton, Aegean cotton, Urfa cotton, Greek cotton) as individual raw materials.Four types of cotton bales were subjected to blow chamber processing and subsequent yarn preparation processes under identical conditions to analyze the effect of cotton type on yarn quality parameters.
An analysis of studies [15,16] on the influence of the speed mode of the main working parts of a carding machine shows that an increase in its productivity is associated with an increase in speed conditions and, first of all, with an increase in the rotation frequencies of the main, take-up and doffing drums.It is necessary to take into account that the accuracy of the manufacture and design of the surface of the drums and set depends on the possibility of changing the layouts in the areas of the take-up -main drums and the main -doffing drums, which leads to an increase in the quality of combing and card sliver while increasing the productivity of carding machines.

Experimental work. Material
The study was carried out on a carding machine RIETER C60 (Switzerland), at that the rotation frequency of the main, take-up and doffing drums was changed when processing medium-fiber cotton with a fiber length of 26.5-28 mm (2.5% span length [mm]) and producing card sliver of linear density Tcs = 4 kTex.In this case, the quality of combing was determined by the amount of neps in combing, using laboratory equipment USTERTESTER-5 (UT-5) [17].Based on these experiments, graphs of the distribution of neps across the width of the drum were constructed at various speeds (Fig. 1).(a, b, c).Based on these experiments, it can be concluded that the distribution of neps in 1 g of combing across the width of the machine is uneven and depends on the amount of deformation of the main drum surface.The number of neps in 1 g of combing decreases the faster the higher the drum speed and the lower the layout.When the main drum rotation frequency increases to 520 rpm and higher, the layout in the main drum -flat assembly is no more than 0.1 -0.14 mm.The number of neps in combing increases by 20% in proportion to the increase in the speed and productivity of the carding machine due to those areas of the surfaces of the working bodies between which there is a large layout.
An increase in the number of neps is also possible due to the fluctuation of the layout due to the eccentricity of the working bodies.
The card sliver obtained by changing the speed modes of the carding machine 2 and 3 tested on the USTER TESTER-5 device (Switzerland) to determine quadratic unevenness and along segments of 5 and 10 meters in length.Table 5 resents the results of the experiments.

Conclusions
Analysis of the experimental research results allows to draw the following conclusions: • an increase in the speed mode of the main working bodies within the studied limits on carding machines does not cause a deterioration in the quality of combing, at that a decrease in the number of neps in 1 gram of combing is observed with an increase in the main drum rotation frequency from 451 min 1 to 520 min 1 .
• with an increase in the speed modes of carding machines, the evenness of the card sliver does not deteriorate and is within the standard parameters.

Fig. 1 (
Fig. 1 (c).The relationship between the average number of neps in combing along the width of the machine at: 4a constant machine productivity of 120 kg/hour; 5when the machine productivity increases from 98 kg/hour to 120 kg/hour.

Table 4 .
The influence of speed modes on the quality of combing and the productivity of carding machines.

Table 5 .
The results of the experiments tested on the USTER TESTER-5 device (Switzerland).