1. The relationship between compact spinning negative pressure and yarn quality
1.1 The importance of compact spinning negative pressure stability to yarn quality
The size of the negative pressure in the compact spinning negative pressure tube is the most direct and critical factor affecting the quality of compact spinning yarn, and the movement state of the fiber whiskers on the negative pressure tube is an important factor affecting the quality of the yarn. factor. When the negative pressure is normal, when the whiskers are transferred from the front roller to the negative pressure tube and when moving on the negative pressure tube, the whiskers move in a relatively straight and continuously shrinking state, but if they are tight Improper adjustment of negative pressure during spinning will cause changes in the movement state of the whiskers, thus affecting yarn quality. The excessive negative pressure of the negative pressure tube causes the whiskers to be tightly adsorbed to the mesh ring, which not only increases the wear of the mesh ring, but also causes poor operation of the mesh ring due to various reasons to more easily affect the movement of the whiskers. ; The negative pressure of the negative pressure tube is too small, resulting in the whiskers on the special-shaped tube not being well controlled, and the whiskers running unstable, resulting in a large amount of cotton ball yarn. Therefore, maintaining a stable and certain negative pressure during the spinning process is The primary factor to ensure yarn quality.
1.2 Negative pressure value of special-shaped tubes
Users can set the negative pressure value according to their own Please select the corresponding negative pressure value of the special-shaped tube slot according to the spinning type and spinning count or number from the table below. If you are spinning blended or chemical fiber products, you can appropriately choose a higher negative pressure (generally in the range of 2300-1700Pa). The specific optimal negative pressure value is determined through experiments based on the actual situation of each company.
Note that a negative pressure that is too high beyond the above table may have less improvement in spinning indicators, but it will cause higher consumption for users. The loss of electricity and short fibers will be greatly increased, which is not conducive to energy saving and consumption reduction.
1.3 The impact of compact spinning negative pressure on yarn quality
Table 2 shows the yarn quality tests of different varieties under different negative pressures:
As can be seen from the above table, the impact of different negative pressures on the compact spinning machine on the yarn The quality will have a greater impact, so an appropriate negative pressure value should be formulated according to the yarn variety and customer quality requirements in order to reduce the difference between yarn spindles and stabilize the yarn quality.
2. The impact of negative pressure compact spinning frame
Negative pressure Analysis of size factors and countermeasures
The negative pressure required by the compact spinning machine is generated by the negative pressure fan at the rear of the car rotating at a certain speed (controllable by a frequency converter). The pressure is transmitted to the special-shaped tube through the negative pressure air cylinder and the negative pressure air duct to obtain the negative pressure value required for spinning to perform normal spinning. During this period, any abnormality in the transmission route from the negative pressure fan to the special-shaped tube will affect the negative pressure of the special-shaped tube, thereby affecting the quality of compact spinning.
2.1 The impact of the exhaust volume of the negative pressure fan host on the negative pressure
The exhaust volume of the negative pressure fan is the most direct and critical factor that affects the quality of compact spinning yarn. The factors that affect the exhaust volume of the negative pressure fan are mainly the following points:
(1) The power of the negative pressure fan. The power of the negative pressure fan has been determined by the manufacturer based on the user’s number of spindles, spinning method (compact spinning or compact siro spinning), type and count of spinning yarn, and will not change under normal circumstances. The power of the negative pressure fan is determined by adjusting the frequency of the frequency converter according to the negative pressure value of the special-shaped tube required for spinning. However, because the negative pressure fan frequency converter has been working continuously in the harsh environment of the spinning mill for a long time, the frequency of the frequency converter will change randomly as the use time increases, resulting in unstable negative pressure fan power and special-shaped tube negative pressure values, affecting Yarn quality stability.
Measures: Check the frequency of the inverter and the speed of the negative pressure fan one by one every week, and repair any abnormalities in a timely manner.
(2) Negative pressure fan exhaust mode. The negative pressure fan exhaust method provided by the manufacturer is to discharge air directly into the workshop, but it will have a great impact on the temperature, humidity and production environment of the workshop. Especially in the high temperature and high humidity season in summer, the workshop temperature can reach over 34 degrees, seriously affecting workers. Therefore, many manufacturers have installed negative pressure fan exhaust ducts. In summer, the heat generated by the negative pressure fan is discharged from the workshop through the exhaust duct. In winter, the heat generated by the negative pressure fan is directly discharged to the workshop to maintain the workshop temperature. However, this measure causes the negative pressure of the same type of spinning frame to be different due to the different exhaust modes in winter and summer and the distance between the exhaust outlet of the negative pressure fan and the outlet of the exhaust pipe, resulting in differences in the negative pressure required for spinning on different spinning machines. Differences between machines affect the stability of yarn quality.
Figure 1 Compact spinning exhaust duct diagram
Measures: According to different If the negative pressure of the machine changes, the frequency of the negative pressure fan should be adjusted in time to ensure that each spinning machine reaches the negative pressure value required for normal spinning.
(3) The negative pressure fan impeller is clean. The rated power of the negative pressure fan used by our company is 5.5��Must be replaced in time.
2.6 Effect of the status of special-shaped pipe components on negative pressure
Because The equipment has been used for a long time, resulting in varying degrees of air leakage in the transmission route from the special-shaped tube to the negative pressure air box at the rear of the vehicle, resulting in differences between compact spinning negative pressure tables and between spindles, affecting the special-shaped tube condensation area The control of yarn slivers results in poor yarn quality stability and large differences between spindles. Among them, the special-shaped pipe joints made of soft rubber harden due to aging, causing the contact deformation and air leakage of the special-shaped pipe joints and the lower connecting pipe of the special-shaped pipes, which is an important factor affecting the stability of the negative pressure value of compact spinning.
Figure 5 Aging and deformation diagram of special-shaped pipe joints
Table 7 shows the negative pressure of new and old special-shaped pipe joints on the suction port of special-shaped pipes Influence.
As can be seen from the above table, the aging and deformation of special-shaped pipe joints also has a greater impact on the negative pressure at the suction port of special-shaped pipes. When the flat sweeper removes the special-shaped pipes for cleaning Pay attention to check the hardening and deformation of special-shaped pipe joints, and replace defective joints in time.
Measures: Use the sweeper to inspect the negative pressure air duct, negative pressure connecting pipe, special-shaped pipe joints, etc., and replace them promptly if air leakage and deformation are found.
2.7 The influence of negative pressure gauge sensitivity on negative pressure
Tight After long-term use of the total negative pressure gauge at the head of the spinning machine, the floating lint and dust in the workshop entered the negative pressure gauge, causing the sensitivity of the negative pressure gauge to decrease. After inspecting and testing the sensitivity of the negative pressure gauges of the 42 compact spinning machines in the workshop one by one, it was found that 8 of the negative pressure gauges did not clear after the pressure was released (maximum 0.2MPa). Under the premise that the negative pressure fan frequency is the same, the special-shaped pipe There are 11 units with large differences in the suction port negative pressure values (maximum >0.4MPa), which results in large differences in the suction port negative pressure of special-shaped tubes when the total negative pressure table values are the same, resulting in yarn quality between yarn spindles. The difference is large, and the CVB value of the yarn stem exceeds the standard.
Measures: Arrange special personnel to regularly check the negative pressure of the special-shaped pipe suction inlets of each machine, and find out the causes and solve them if any abnormalities are found.
3. Determine the optimal negative pressure value
Through the above comparison Analysis of the factors affecting the negative pressure value of compact spinning and the adoption of corresponding measures. When the sensitivity of the compact spinning negative pressure meter is not high, in order to ensure the relative stability and uniformity of the negative pressure value of the same variety of compact spinning, the speed of the negative pressure fan should be controlled. The frequency is a standard, and the negative pressure value displayed on the negative pressure gauge on the front of the vehicle can only be used as a reference. At the same time, regularly check the speed of the negative pressure fan and the changes in negative pressure at the suction port of the special-shaped pipe. After experimental comparison, our company has made the following regulations for various types of negative pressure: Table 8 (Negative pressure table negative pressure unit: Kpa)
Note: Variety network below or equal to 40s The grid mesh number is 120 mesh, and the grid mesh number for varieties higher than 40s is 140 mesh.
4. Conclusion
Ensure stable suction port for compactly spun special-shaped tubes The negative pressure value is a prerequisite for ensuring yarn quality, but there are many factors that affect the negative pressure of compact spinning. Ensuring the stability of negative pressure in compact spinning is a complex system project. During production, it is necessary to promptly discover the changes in the compact spinning negative pressure on different machines based on the actual situation, and promptly find the reasons and solve the problem to ensure the stability of the compact spinning negative pressure and ensure good yarn quality. </p
