Abstract
Aiming at the optimization of spindle process parameters, a mechanical lifting collective doffing spinning frame was discussed The importance of the setting of the spindle speed to the head retention rate during operation; the setting of the spindle speed is calculated through a combination of theoretical analysis and on-site debugging. It is pointed out that after the spindle process parameters are optimized, the end-break rate of the spinning frame can be reduced, the labor intensity of spinning workers can be reduced, and the end-retention rate of start-up, work efficiency and cotton spinning mill output can be improved.
The influence of spindle speed on spinning efficiency
At present, mechanical lifting ring plate spinning Machinery still accounts for a large proportion of textile mills. In order to reduce the labor intensity of the workers, reducing the end-breakage rate during starting and doffing and improving the end-retaining rate during starting have become major research topics for every textile factory and textile machinery manufacturing enterprise. In the spinning process, the end-break rate is related to many factors, such as: spinning raw materials, spinning speed, temperature and humidity, management, technology, etc. Among them, the spindle speed is the main factor affecting the end-break rate. The author combines theory with on-site debugging to analyze the impact of ring spinning machine spindle speed on the end-retention rate.
Traditional manual doffing mainly involves manually pulling out the yarn and retracting the covering yarn onto the spindle bar. When the new yarn bobbin is pressed onto the spindle bar, the yarn is withdrawn from the spindle bar. Press it down to achieve the purpose of keeping the head. The collective doffing on the market today achieves the purpose of retaining the end by winding the yarn onto the waste silk disc of the aluminum sleeve spindle during doffing. If you want to achieve the best end-retaining effect and the covering yarn will not retreat to the spindle bar when the full yarn is pulled out, it is best to ensure that the number of turns of the covering yarn is 1 to 2 turns, and the number of turns of the covering yarn It is mainly adjusted by the spindle speed during doffing.
Theoretical calculation of spindle speed
In order to improve the yarn retention rate during driving and prevent the spindle from spinning during doffing The problem of yarn rewinding is to prevent the yarn rewinding from the spindle from hindering the movement of the traveler. We need to adjust the combination of the number of turns of the covering yarn and the waste wire tray during doffing. In addition to electrical reasons, we mainly analyze the doffing spindle speed and the doffing ring plate descending speed. The spindle speed during doffing of the spinning frame is mainly set based on the twist degree, mechanical lifting sprocket and worm gear transmission ratio y, servo motor frequency Z, ring plate lifting motor speed and other data.
Take the JWF1510 spinning machine manufactured by Jingwei Co., Ltd. Yuci Branch as an example. Figure 1 shows the mechanical part of the head box that controls the doffing of the ring plate.
The ring plate lifting motor transmits the motion to the lifting sprocket and the traction belt through the sprockets 1, 2, 3, 4 and the worm gear mechanism 5, and the traction belt drives the steel ring plate. The collar board descends to complete the doffing movement. According to the number of sprocket teeth and the worm gear ratio, the descending speed of the ring plate during doffing is ν=1 400 It can be concluded that the descending linear speed of the ring plate ν=6.28×π×140/60—46 (mm/s).
In a test at a spinning mill in Hunan, a certain type of thick yarn with a twist of 495 t/m was spun. When the doffing speed was 3 220 r/min, the covering yarn is 1 circle. In order to reduce end breaks, the spindle speed curve during the spinning process must ensure a smooth arc transition. Therefore, when spinning large yarns, the yarn speed is too low and the yarn is loose, which affects the output. To solve this problem, we can swap sprockets 2 and 3. The entire sprocket transmission ratio can be increased: 13/13×16/40/(13/16×13/40) = 1.5 times, and the ring plate is lowered. Linear speed: ν1=ν×1.5=46 X 1.5=69 (mm/s).
Through the test, when the above sprocket is replaced, the doffing speed reaches 4 830 r/min, and the covering yarn is 1 turn, then the actual front roller yarn output speed ν1′ =4 830/495—162.6 (mm/s), which is 24.6mm (162.63—138) different from the yarn length 138 mm (69 X 2) required for the straight descent of the ring plate.
If the servo motor frequency is 50 Hz, the calculated relationship between the frequency converter operation and the spindle speed is approximately 325 r/Hz. According to the fluctuation of yarn tension during the spinning process, the yarn tension reaches the maximum when doffing, and the yarn tension is lower than the doffing state when starting. In order to make the tension uniform, the “little braid” yarn is thrown away to reduce end breakage and start. The speed can be appropriately increased relative to the doffing speed. When the spindle doffing speed is 4 830 r/min, the starting speed can be set to 6 000 r/rain. The doffing speed is converted into a frequency percentage of about 4 830/325/50-30%, and the starting speed is converted into a frequency percentage of about 4 830/325/50-30%. 6 000/325/50-37%. According to the experiments and adjustments of the spindle multi-stage speed control and adjustment system, the spindle curve setting parameters are shown in Table 1 and Figure 2 respectively.
In order to increase spinning output and adapt to different spinning numbers, sprocket 1 can be replaced with a 15-tooth, 17 teeth, 21 teeth, etc., before and after the exchange of sprocket 2 and sprocket 3, the descending speed of the ring plate is as follows.
15 teeth: Before replacement, the descending speed of the ring plate was 53 mm/s. After replacement, the descending speed of the ring plate was 79.5 mm/s.
17 teeth: Before replacement, the descending speed of the ring plate was 60 mm/s. After replacement, the descending speed of the ring plate was 90 mm/s.
21 teeth: Before replacement, the descending speed of the ring plate was 74 mm/s. After replacement, the descending speed of the ring plate was 111 mm/s.
According to the length difference calculated above, when the step-up motor sprocket has 15 teeth, the same twist is 495 twist/m. In order to meet the requirement of 1 turn of covering yarn, then Linear speed during doffing = yarn length required for the ring plate to drop in a straight line + length�Difference = (79.5×2+24.6)mm/s=1 1m/min, doffing spindle speed: 11m/min X 495 twist/m=5 445 r/min.
When the upgrading motor sprocket has 17 teeth, the same twist is 495 twist/m. In order to satisfy one turn of the covering yarn, the linear speed during doffing is one steel ring The length of yarn required for the plate to fall in a straight line + the length difference = (90X2+24.6)mm/s=12.27 m/min, the doffing spindle speed: 12.27×495 twist/m=6 073 r/min.
When the upgrading motor sprocket has 21 teeth, the same twist is 495 twist/m. In order to satisfy one turn of the covering yarn, the linear speed during doffing = steel ring The length of yarn required for the plate to drop in a straight line + the length difference = (111 .
Based on the above calculation of the 13-tooth sprocket, the starting speed and spindle curve after replacing several other sprockets can be obtained from the doffing spindle speed.
Conclusion
This article combines theoretical analysis with on-site debugging. The setting of the spindle speed was calculated. The above theoretical calculations have been verified on site, and the effect is quite significant for mechanical lifting ring plate spinning machines. By optimizing the settings of process parameters such as doffing spindle speed and spindle speed curve, spinning breakage can be greatly reduced. efficiency, improve the head retention rate during driving, increase output, and reduce labor intensity.
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