1.1 Three-roller double-draft zone structure
1.1.1 RingCan ring spinning frame technology
In the course of the development of cotton spinning super-large drafting technology, the information closest to the industrial application is the RingCan ring spinning machine prototype displayed by Germany's Xusen Company in ITMA 1999. The company has developed the super-large drafting structure of three-roller three-apron cotton sliver direct spinning since the 1980s. The cotton sliver is fed into the ring spinning machine by the roller with a diameter of 250mm, which can produce more than or equal to 20tex (30 counts) of yarn, mainly used for weaving denim. The sliver wrapped in the sliver drum is guided by the single spindle conveyor belt for synchronous conveying, and fed into the drafting area of the spinning frame through a relatively closed pipeline conveying system. The maximum draft ratio of the back zone can be set to 3.5-4.0 times, the total draft ratio can be 3.0-4.0 times higher than that of ordinary ring spinning, and the maximum total draft ratio can reach 250 times. In the example, the total draft ratio of spinning 20 tex (30 count) yarn is 176 times, and the calculated feed sliver weight is 352 tex. Compared with ordinary ring spinning process, it is a light weight sliver. The application of roving process is defaulted in the spinning process. In order to stabilize the drafting quality, the blending and drafting of three drawing frames are set up in the pure cotton carding process, so that the number of process configurations between carding and spinning processes is odd, thus complying with the odd-number rule of cotton spinning process. The test data provided by Xusen Company shows that the quality level of the short segment test of the spinning quality of RingCan ring spinning frame is better than that of the traditional ring spinning yarn.
For more than 20 years since then, RingCan ring spinning machine spinning technology has never been heard of, and there is no product market application information, as well as exchange and discussion related to this technology. Whether it is the technical and economic problem of RingCan oversize drafting device or the default roving process of sliver direct spinning is not suitable for the industrial application of cotton spinning, there is no clear conclusion.
1.1.2 Japan Toyoha three rubber ring super drafting system
Figure 1 is a schematic diagram of the patent application No. 96107383.7 of Japan's Fenghe. The drafting device is equipped with an upper pin apron structure on the rear upper roller of the traditional three-roller double-apron drafting device, a lower pin bar is added in the rear drafting area, and a cluster is added at the entrance of the middle roller jaw to form a set of three-roller double-zone three-apron high draft system, with a maximum nominal draft multiple of 280 times, The roving frame can be defaulted for sliver direct spinning. The technical structure is very close to that of Tsumori RingCan. The three-roller three-apron drafting device is attached with a control element composed of upper and lower pins and upper apron in the back area, which effectively increases the drafting capacity in the back area. Figure 2 shows the correlation between the drafting multiple in the back area and the yarn density uniformity. From the curve, it can be seen that the drafting quality is the best when the drafting multiple in the back area is 4.0. This technological route is to greatly improve the total drafting capacity by increasing the draft multiple in the back area when the upper apron is set in the rear jaw, because the rear jaw drive and sliver control are still dominated by the rear lower roller, which will not affect the dynamic stability of the total draft multiple, thus ensuring the stability of the linear density uniformity of the long segment of yarn.
Although the drafting structure claims to be capable of direct spinning of sliver, the open example application is still the drafting of twisted roving. Table 1 shows the comparison of spinning test data between the traditional three-roller double-apron drafting system and the Fenghe three-roller three-apron high power drafting system, both of which are fed with twisted roving to spin CJ19.7 combed pure cotton yarn and CJ14.8 combed pure cotton yarn:
Note: The author obtained data from Japan in the late 1990s in 1999. The original data is in English, and the author converts it to metric
In the following 2000, a Shanghai applicant applied for the patent of three rollers, three rubber rings and four rollers, three rubber rings with application number 00249589.9. The structure of three rollers and three rubber rings is basically similar to that in Figure 1.
1.1.3 Three-roller four-rubber ring super drafting
Figure 3 is the attached drawing of the patent application of the Jiangsu applicant with application number 00221765.1. The upper and lower pins and a pair of long and short rubber rings are added in the rear area of the three-roller double-zone drafting, forming a three-roller double-zone four-rubber ring (two sets of long and short rubber ring jaws) ultra-large drafting device. The specification says that the total drafting capacity can be greatly enhanced by increasing the draft multiple of the rear area, and the ultra-large drafting application of cotton sliver direct spinning can be realized.
After that, the Shandong applicant's application No. 01243901.0, the Jiangsu applicant's application No. 200520073617.2 and the Shanghai applicant's application No. 200720066977.9 all proposed the technical structure of three rollers and four rubber rings similar to Figure 3.
The above three roller and four apron drafting technical schemes have not been disclosed for the industrial application of ultra-large drafting for sliver direct spinning. However, the three-roller four-apron drafting device is used as a large-drawing spinning process fed by roving, which is currently applied in some domestic cotton spinning enterprises (Figure 4), and is mainly used to produce low-linear density (high-count) yarn with twisted roving.
1.2 Structure of four-roller and three-draft zone
In the four-roller three-draft zone draft structure, there are three to six rubber rings.
Figure 5 is the patent application drawing of the four-roller three-apron drafting structure of the Shandong applicant. It is to add a pair of roller jaws at the upstream of the three-roller three-apron drafting structure to form a four-roller three-apron drafting structure. Its drafting capacity is no more than that of the three-roller three-apron drafting structure.
The four-roller four-apron drafting structure in Figure 6 is a utility model patent application of Guangdong applicant in 2002. It is an additional set of double-short apron jaws on the upstream of the traditional three-roller long-short apron jaws, which becomes a four-roller three-zone four-apron super-large drafting device. The specification says that the total drafting capacity can be greatly enhanced by increasing the rear zone drafting multiple, which can realize the super-large drafting application of sliver direct spinning.
The four rollers and four rubber rings in Figure 7 adopt two sets of long and short rubber ring jaws set continuously, and double control rods are added in the rear area. In the example, we still use roving feeding to spin 60-100 count yarn. The back zone uses the back zone double control rod type with innovative and efficient technology at the beginning of the 21st century. The simple roller plane drafting structure is changed to the curve drafting through the double control rods. The upstream control rod presses down the whisker to add the surrounding arc between the whisker and the back roller. The downstream control rod lifts the roving strip so that it does not change the feeding status of the middle jaw, so that the speed change point of the back draft whisker can be further moved forward and concentrated.
Figure 8 is based on the four-apron structure in the front and middle areas of the four-roller, and a pair of upper and lower pin double-short apron jaws are added in the rear area to become a four-roller six-apron super-large drafting device with three consecutive sets of apron jaws. The patent specification says that the total drafting capacity can be greatly enhanced by increasing the drafting multiple in the middle and rear areas, and the super-large drafting application of sliver direct spinning can be realized.
In several technical schemes of four rollers and three draft areas, there are two important defects in the process structure. The first is to set the second rubber ring jaw on the third roller (Fig. 5 and Fig. 7). Since the rubber ring jaw will inevitably slide relative to the roller movement, it is easy to produce the dynamic variation between the two adjacent rubber ring jaw draft areas with large draft multiple configuration, and the distribution of the draft multiple on time and spindle, It is not conducive to the stability of drafting process and increases the variation of linear density uniformity; The second is to set the second apron jaw on the fourth (rear) roller (Fig. 6). Since the movement of the apron jaw relative to the rear roller will inevitably lead to slippage, it is easy to produce the dynamic variation of the total draft ratio on time and between spindles, which is not conducive to the control of yarn weight unevenness. However, the scheme in Figure 8 may have defects in both aspects of process structure.
1.3 Five-roller four-draft zone structure
Figure 9 is similar to adding a pair of rear roller jaws on the basis of the four-roller four-apron structure in Figure 6 to form a super-large drafting structure of five-roller four-apron four-drafting area, which not only avoids the two important technical structural defects of the upper section analysis, but also realizes the drafting structure setting of two pairs of apron jaws in series in the same direction. It is expected to greatly enhance the total drafting capacity, and can use cotton sliver direct spinning for super-large drafting. The five-roller drafting system is composed of five rollers with the same shape and size. It is expected to exceed the total drafting multiple that can not be reached by the general three-roller spinning frame. The sliver produced by the drawing frame can be directly fed into the five-roller drafting system, and then twisted after high power drafting to directly obtain the yarn. The test shows that the spinning effect of 27.8~36tex (21~16 count) yarn sample on five-roller spinning frame is good when the total draft of common carding cotton varieties is less than 150 times. The technical proposal also mentions that the sliver storage device for feeding slivers into the spinning frame is arranged on the upper floor or the same floor of the ring spinning frame.
1.4 Brief analysis of the influence of multi-roller drafting area on drafting quality
The design of the drafting device is to improve the drafting capacity on the premise of ensuring the drafting quality. The adoption of the multi-roller multi-apron jaw drafting area will increase the drafting capacity while producing three major technological structural defects that affect the drafting quality: the setting of the adjacent apron drafting area, the setting of the rear roller apron jaw, and the setting of the fiber speed change point in the same direction and multistage series drafting structure:
1) The adjacent apron drafting area is set. Due to the dynamic and uncertain slip of the two pairs of apron jaws, the distribution of the drafting multiple of the two drafting areas is unstable with time and between spindles, which affects the linear density (evenness) of the spinning short segment and the unevenness between spindles.
2) The setting of the jaw of the rear roller apron, due to the dynamic and uncertain slip of the rear apron, makes the setting of the total draft multiple unstable with time and between spindles, affecting the linear density (weight) of the long segment of yarn and the unevenness between spindles.
3) The fiber speed change point is set in the same direction and multistage series draft structure. In the process of centralized control of the forward movement of two or more speed change points in the same direction, the draft wave in the upstream draft area will be superimposed on the downstream draft area, resulting in a serious deterioration of the linear density distribution. The larger the draft multiple in the upstream draft area, the more significant the superposition of the draft wave.
Therefore, simply increasing the drafting area of the co-extending apron jaw or other fiber control types, and adding the friction boundary structure to control the shift point forward concentration, can not increase the drafting ability proportionally while ensuring the drafting quality. In order to achieve about 200 times of super-large draft, we must also find new protrusions
source:https://mp.weixin.qq.com/s/QkGQS47FBYRlGqHkhhVx_g