Pay attention to some points in the use of overflow dyeing machine

One, the adjustment of the return valve

The original overflow dyeing machine is equipped with Ⅰ, Ⅱ, Ⅲ, three return water valves, which are generally installed on the left rear of the machine (Figure 2). They are mainly used to control and adjust the operation of the fabric and the machine. Distribution status within. Practice has proved that

Valve I should be relatively open, while valves II and III, especially the last valve III, should be opened smaller. Valve II is generally after the dyeing machine is debugged normally, even if there is little change in the processed product, you can change it. It is fixed, in short, the dyeing solution in the machine should be fully inclined to the overflow trend, which is the characteristic of the overflow dyeing machine. On the contrary, if the valve Ⅲ is opened larger, especially for light and thin fabrics, the fabric will lag, which will affect the smooth flow of the fabric, and even cause turmoil, resulting in knotting and blocking of the fabric; and it will also increase the effect of the nozzle part on the fabric. Increasing the tension causes the empty play between the cloth guide roller and the nozzle, which is prone to cracking of light and thin fabrics, and scratch marks on the surface of heavy fabrics, resulting in excessive local tension and unequal shrinkage of the fabric. The mechanical defects can usually be solved by adjusting the return valve.

At the eleventh China Textile Exhibition, I saw an under-walking "caterpillar" AK-SL from Asia. It only has two liquid return valves, regardless of whether it is from the debugging of the machine itself and the processing of the dyeing and finishing plant when it is applied. Variety changes are easy to adjust. From the perspective of dyeing, in fact, the front/rear two valves are more reasonable to adjust the liquid return in the machine than the original three valves. I also mentioned above that the valve II on the original machine is basically useless in production. Isn't it possible? Is it superfluous?

Second, the choice of nozzle

There are nozzles on the overflow dyeing machine, and their diameters are generally 50, 60, 70, 80, 100mm. >100mm nozzle.

2.2.1 For light and thin fabrics, such as polyester mosquito netting, voile, pongee, shiny jersey and feather yarn, etc., their weight is generally between 50~100g/m2, choose a 50mm nozzle as should.

2.2.2 General fabrics, such as polyester/viscose medium-length wool-like fabric, polyester gabardine, Crodin, tripe cloth, T/C, N/C and other blended interwoven fabrics, etc., and their weight is between 150~300g/m2 It is advisable to choose a nozzle of 60 or 70mm.

2.2.3 Thicker fabrics, such as polyester canvas, terry cloth, polyester and its blended woolen cloth, general leather-like products, their weight is about 400g/m2, it is appropriate to choose a nozzle of 100mm; the thickest You can even choose a large nozzle above 100mm.

First of all, when choosing, the diameter of the nozzle should be slightly wider than the diameter of the fabric rope (wet state). The knots cross the nozzles. Secondly, the nozzle must be carefully and steadily disassembled, fixed on the three screws in all directions, and not shaken after inspection. Finally, when dyeing with double-tube and multi-tube overflow machines, it is best to strive to be consistent with the weight and length of the fabric in each tube. Practice has proved that the difference between the weight and length of the tube and the tube is 10-15%. It's not a big problem, otherwise there will be a pipe error.

Three. Elimination of clogging

Using overflow jet dyeing, clogging seems inevitable. After long-term observation, it is believed that whether it is an imported machine or a domestic machine, if it is used improperly, there will be different degrees of cloth blocking. There are four reasons: Adding materials, sometimes due to changes in processing varieties, and some mechanical devices have not been adjusted, such as liquid return valves, nozzles, etc., and they are eager to dye and cause mechanical clogging; ②Sometimes for some light, thin and high-density fabrics, such as spring After entering the machine, such as Yafang and Ditafu, they are not going down, but floating on the liquid surface. Take measures such as adding a deaerator in the dye bath to let the air in the fiber exhaust, and the fabric is easy to knot and block the fabric. In this way, it is necessary to check the fabric, order the process, and select the auxiliary agent to prevent the problem; ③The operator will transport the fabric. If you enter the dyeing machine, everything will be fine! And you still have to pay attention to whether the fabric in the machine is blocked from time to time. Once you find that the recoil blocking device is activated immediately, it is easy to eliminate it. If the fabric is fed into the machine, will the foam in the dye bath increase? Because sometimes the defoamer is not added or the amount is not added properly, or the foam suppression effect is poor, or even High water hardness will produce foam at room temperature, which will produce "pneumatic" and form clogging. It must be pointed out that if you need to add a defoamer during dyeing, you should add it before the foam appears. This has a better anti-foaming effect. . In addition, I think that the utilization rate of computers equipped with domestic intermittent dyeing machines is generally only about 70%, and about 30% of the problems still need to be solved by the proficiency of the operators, which is the expensive imported overflow jet. The computer on the dyeing machine is also unlikely to have a 100% effect, because the factors that affect the success of dyeing at a time are really hard to detect, which is completely understandable. I have told my colleagues many times that batch dyeing production technology is a workshop-type production technology, unlike continuous pad dyeing, which is an industrialized production technology.

Fourth, the safety of operation

(1) Opening and closing: When dyeing is finished on any high temperature and high pressure dyeing machine, the steam valve must be closed first to cut off the heat. Then open the pressure-reducing valve, wait until the pressure drops to "O" megapoise (Mpa), and at the same time, lower the temperature in the dyeing machine to below 85°C before opening the lid. Sometimes, even under these conditions, if you still can’t open the cover at hand, it is often because the relevant watch has malfunctioned. I am afraid there is still pressure in the machine. Then you must calmly find the reason. Don’t open the cover bluntly. Although the machine is operating normally, if the temperature inside the machine has not reached 95°C, please do not close the pressure relief valve, try to let the air in the machine out, especially the half-filled dyeing machine, because of the saturation in the machine. The steam pressure is generally not increased until the temperature rises to a little above 99°C, so closing the exhaust valve prematurely will not only cause virtual pressure in the machine, which will cause light discoloration, but also easily cause foam, which will cause the circulation pump The occurrence of "air blow" will cause abnormal phenomena such as knotting and clogging.

(2) Special attention should be paid to safe operation of the high temperature and high pressure overflow dyeing machine: such as the tempered glass observation window installed on the machine, when the dyeing temperature in the machine exceeds 100 ℃ or more, it must not be wiped with a damp cloth, because the glass is highly / The effect of the low temperature difference, the occurrence of intense thermal expansion and contraction, resulting in cracking, is very dangerous! In addition, after the liquor ratio of the water level glass tube is adjusted, the stop valve at the upper and lower ends should be closed. Although these are trivial matters, the author has witnessed a few things. Big disasters are caused by these little things, so I still have to remind everyone to pay attention to a big thing!

(3) Sampling problem: For fabrics dyed on a double-tube or multi-tube overflow machine, it is best to take a dye sample on each tube for color matching with the standard sample. Under normal circumstances, the color obtained in each tube should be the same, but sometimes due to the different cloth length in each tube, or the circulation of the heat exchanger is abnormal, or the filter is not cleaned for a long time, it causes partial blockage, or the feed concentration is high. Fast, etc. will cause the color difference between the tube and the tube. Since the chromatic aberration is caused by these main factors, it is necessary to pay attention to the normality of these parts in daily production, and solve the problems in time.

(4) Maintenance and repair: high temperature and high pressure overflow dyeing machine, no matter the small prototype or the large-scale production machine, the most important thing is the sealing ring (washer). Practice has proved that the same fabric on the same processing list, the same pre-treatment, Why sometimes there are cylinder differences? For a long time, I have been aware that most of them are because of the difference in the sealing performance of each dyeing machine. Just as long as there is a leak in the joint, it will not only affect the color difference, the size of the air leakage, and the uneven dyeing. , And it also has heat energy. Therefore, in addition to the problems mentioned in 2.4.1. above, it is very important to improve the sealing of the dyeing machine. If the leak is found, replace it in time. In addition, if the safety valve, thermometer and pressure gauge are normal, please refer to the "Comparison Table of Temperature and Saturated Steam Pressure Constant" (Table 1). If any discrepancy is found, check immediately to find out the problem and correct it in time. Don't just use one meter, that is, if you just look at the thermometer to 130°C, it is considered to be 2kg/m2 (pressure), which is prone to accidents! Finally, the whole machine is overhauled and maintained once a year, and the main components are repaired and maintained for half a year. Once, the wearing parts are inspected and maintained once a month, and the oil is added once a day, and daily cleaning is done. This is very closely related to extending the service life of the machine, ensuring safe production, and improving the quality of dyeing each time. "The big hole bears hardship", especially the workshop management should strengthen supervision.