A spinning process for improving the quality of polyester FDY bottom yarn

Abstract

The present invention relates to a spinning-in process for improving the quality of polyester FDY bottom yarn, by continuously adjusting the temperature T of the hot roller. GR , so that after the secondary switching starts, when the yarn passes through the hot box where the hot roller is located, the temperature of the yarn on the hot roller is always the same. The spinning process for improving the quality of the bottom layer yarn of polyester FDY of the present invention makes the quality of the bottom layer yarn produced equal to the quality of the outer layer yarn of the yarn cake.

Description

Technical Field

[0001] The invention belongs to the technical field of spinning processing and relates to a spinning process for improving the quality of polyester FDY bottom yarn. Background Art

[0002] In the production of polyester chemical fiber FDY products, the first hot roller heating and stretching and the second hot roller heating and shaping are the most important process points. All process values ​​must be kept stable in production to ensure product quality. The fluctuation of the hot roller temperature is generally kept within the range of ±0.5℃ under the control of the computer system.

[0003] Due to production needs, when there are a lot of oils and polyester decomposition substances remaining on the surface of the hot roller, it is necessary to stop the operation and heating of the hot roller, and wipe the surface of the hot roller and the inside of the hot box with clean water. This causes the surface temperature of the hot roller and the ambient temperature in the hot box to drop. After the spinning, the temperature in the hot box will be unstable for a period of time, affecting the product quality.

[0004] The FDY spinning process is low-speed spinning and high-speed spinning. During the spinning process, the hot roller and the winder are at a low speed, about 50-80% of the production speed. The filament bundle is wound manually and switched to a spindle of the winder. This switching process is called one switching. After that, the hot roller and the winder start to speed up to the production speed. The speed-up process takes about 50-90s. After the hot roller and the winder speed are increased to the production speed, they are switched again. The filament is switched to the spare spindle of the winder to start production. This switching is called the second switching. After starting the hot roller, it takes 15-30 minutes for the ambient temperature of the hot box to return to the stable value. It takes 5-10 minutes from starting the hot roller to the end of the second switching. It takes 10-20 minutes from the end of the second switching to the ambient temperature in the hot box returning to the stable value. Figure 1 As shown in the figure, it is a temperature-time curve of a certain hot box after the secondary switching is completed, and the ambient temperature of the hot box returns to a stable value. It takes about 15 minutes for the ambient temperature of the hot box to return to a stable value after the secondary switching. The part produced before the ambient temperature of the hot box is stable is the bottom layer of silk, and its physical properties and dyeing are somewhat different from those of normal silk (the outer layer of the silk cake). Usually, the low temperature of the first hot roller and the hot box will cause uneven heating of the tow, which may cause the tow to stretch and become hairy or increase the unevenness of the yarn; the low temperature of the second hot roller and the hot box will affect the thermal setting of the tow, which may cause changes in the elongation at break and the boiling water shrinkage of the tow.

[0005] In actual production, in order to reduce such impacts, the following methods can be used:

[0006] ① Switch the waste small rolls, that is, 10-20 minutes after the spinning is completed, manually switch the silk produced by the spinning position to avoid the influence of abnormal silk.

[0007] ② During the yarn-making process, after the yarn bundle is wound around the hot roller, close the door of the hot box and wait for 10-20 minutes to allow the temperature in the hot box to stabilize before switching the yarn bundle to the winding machine to start production. During the yarn-making process, a suction gun is used to suck the yarn bundle into the pipeline and collect it in the waste yarn room. Before switching to the winding machine to start production, the yarn bundle is treated as waste yarn.

[0008] Both methods will generate a large amount of waste silk, reduce production efficiency and increase production costs. At the same time, due to the increase in manual operation steps, there are human operation errors, and it cannot be guaranteed whether the switching time is appropriate. During manual operation, if the switching time is too short, it may cause abnormalities in the bottom layer of silk cake. If the switching time is too long, it will cause waste and reduce production efficiency. At the same time, manual operation may lead to the possibility of forgetting or missing cutting.

[0009] In addition, due to the differences in equipment between different spinning positions, the changes in the hot box ambient temperature are different, and the differences in the spinning position stop time lead to different reductions in the hot box ambient temperature. As a result, the time required for the hot box ambient temperature to return to stability at each spinning position is also different. Manual operation can only reduce the amount of abnormal silk, but cannot completely avoid it.

[0010] Therefore, it is of great significance to study a spinning process for improving the quality of polyester FDY bottom yarn to solve the above problems. Summary of the invention

[0011] In order to solve the problems existing in the prior art, the present invention provides a spinning-in process for improving the quality of polyester FDY bottom yarn;

[0012] To achieve the above object, the scheme adopted by the present invention is as follows:

[0013] A spinning process for improving the quality of polyester FDY bottom yarn adopts a two-step spinning process (i.e., low-speed spinning and high-speed spinning, requiring one and two switchings). First, the temperature of the hot roller T is set. GR The value is equal to the hot roller process temperature HT, and then the hot roller is started to spin the head. By continuously adjusting the hot roller temperature T GR , so that after the secondary switching starts, when the wire passes through the heat box where the hot roller is located, the temperature of the wire on the hot roller is always the same.

[0014] As the preferred technical solution:

[0015] As described above, a spinning-in process for improving the quality of polyester FDY bottom yarn is performed by setting the temperature T of the hot roller during a switching process. GR The value is equal to the hot roller process temperature HT and the hot roller heating compensation temperature T b The sum of the hot roller temperature T GR = HT+T b), spinning is carried out after the secondary switching is completed (the secondary switching is completed when the spinning is completed); the hot roller process temperature HT is the hot roller temperature when producing the outer layer of the silk cake (when producing the outer layer of the silk, the production process is stable. In order to stabilize the production and improve the quality of the silk, the outer layer of the silk cake in the prior art usually refers to the silk produced 30 minutes after the secondary switching is completed); T b satisfy:

[0016] ;

[0017] Among them, λ 2 is the thermal conductivity of the air in the hot box, F 2 is the contact area between the wire and the air in the hot box, δ 2 is the heat transfer distance between the wire and the air in the heat box (i.e. the thickness of the air), λ 1 is the thermal conductivity of the wire, F 1 is the contact area between the wire and the hot roller, δ 1 is the heat transfer distance between the hot roller and the wire (i.e. the thickness of the wire), T c is the temperature of the hot roller T GR Rise to the hot roller process temperature HT and the hot roller heating compensation temperature T b The ambient temperature of the hot box at the Kth second after the sum of the values, where the Kth second is within the period from the start of the first switching to the start of the second switching;

[0018] λ 2 It is 0.032W / m·k, and the thermal conductivity of air at 100℃ is selected;

[0019] F 2 The calculation method is: F 2 = (total length of the wire in the heat box - length of the wire in contact with the hot roller) * circumference of the cross section of the wire;

[0020] δ 2 The calculation method is: because the wire is wound on the circumference of the hot roller, the remaining volume after subtracting the hot roller and the wire from the volume inside the hot box is divided by the circumference of the hot roller to get the thickness of the air;

[0021] λ 1 is the thermal conductivity of the silk, i.e. the thermal conductivity of polyester, which is 0.084 W / m·k;

[0022] F 1 The calculation method is: F 1 =The length of the wire in contact with the hot roller * the width of the wire;

[0023] δ 1 is the thickness of the wire, measured directly;

[0024] T c It can be obtained by directly testing with the equipment;

[0025] Among them, the temperature of the hot roller is T GR Rise to the hot roller process temperature HT and the hot roller heating compensation temperature T b After the sum, wait for a while until the ambient temperature of the hot box is equal to T c When the heating rate is increased in real time according to the ambient temperature of the hot box, the heating compensation temperature T of the hot roller is reduced at the same rate. b until the ambient temperature of the hot box is equal to the central value of the ambient temperature of the hot box T 0 , hot roller temperature T GR Equal to the hot roller process temperature HT; when the equipment and production process are stable, the ambient temperature in the hot box will be stable within a certain temperature range, and the temperature fluctuation is within ±0.5℃. If the temperature deviation is too large, generally exceeding 3℃, it will affect the product properties and dyeing. The center value of the hot box ambient temperature is T 0 It is the average value of the hot box ambient temperature when producing the outer layer of the yarn cake.

[0026] When there are a lot of oil and polyester decomposition substances left on the surface of the hot roller, the operation and heating of the hot roller should be stopped, and the surface of the hot roller and the inside of the hot box should be wiped with clean water, causing the surface temperature of the hot roller and the ambient temperature in the hot box to decrease. When the yarn is ready for production, the temperature of the hot roller reaches the production temperature, but the ambient temperature in the hot box does not meet the production temperature requirements. While the hot roller heats the yarn, since the ambient temperature in the hot box has not yet reached the production temperature requirements, the yarn will also dissipate a lot of heat to the air in the hot box, making the temperature of the yarn on the hot roller always lower than the temperature of the yarn on the hot roller during stable production (that is, when producing the outer layer of the yarn cake), and the production quality of the yarn is poor. In this process, as the yarn and the hot roller continue to dissipate heat, the ambient temperature in the hot box will continue to rise and change, and the heat dissipation of the yarn will also continue to decrease. When the ambient temperature in the hot box meets the requirements of stable production, the production quality of the yarn is excellent.

[0027] Since the heat roller is made of metal and is in direct contact with the wire, the thermal conductivity of the wire is higher than that of the air. When the amount of heat transferred is the same, the temperature difference between the wire and the heat roller will be significantly smaller than the temperature difference between the wire and the ambient temperature of the hot box (i.e., the temperature of the air in the hot box). Therefore, only the heat roller needs to compensate for a smaller temperature to make up for the larger temperature difference between the wire and the air. Under the premise of continuous heat dissipation, the heat that the wire can retain is the same as the heat retained during stable production, thereby stabilizing the temperature of the wire and solving the problem that the ambient temperature in the hot box does not meet the production temperature requirements.

[0028] As the spinning process progresses, the ambient temperature of the hot box increases, and the temperature difference between the ambient temperature of the hot box and the silk decreases. Although the heat dissipation of the silk to the air is still greater than that of the silk to the air during stable production, it is constantly decreasing. In order to ensure that the quality of the bottom layer of silk produced is the same as that of the outer layer of silk cake, it is necessary to continuously reduce the thermal compensation temperature T b, so that the heat compensated by the hot roller to the wire is consistent with the heat lost to the air by the wire (that is, compared with the stable production, the heat lost to the air by the wire). The heat compensated by the hot roller to the wire is consistent with the heat lost to the air by the wire, which ensures the continuous reduction of the thermal compensation temperature T b After that, the heat transfer from the hot roller to the wire is always the same as the heat transfer from the wire to the air. The heating compensation temperature of the hot roller is T b The cooling rate needs to be the same as the heating rate of the hot box environment, so as to achieve a dynamic balance between the hot box environment temperature and the hot roller temperature, and ultimately ensure that the quality of the bottom layer of silk produced is the same as the quality of the outer layer of silk cake.

[0029] "Hot roller heating compensation temperature T b The cooling rate needs to be the same as the heating rate of the hot box environment. The specific derivation process is as follows:

[0030] First, assume that the temperature of the wire in the heat box at the Kth second after the heat roller is heated to compensate for the temperature is the same as the temperature of the wire during stable production; the Kth second is within the period from the start of the first switching to the start of the second switching;

[0031] During stable production, the heat transferred by the hot roller to the wire is:

[0032] (Formula 1);

[0033] Among them, λ 1 is the thermal conductivity of the wire, F 1 is the contact area between the wire and the hot roller, T s is the temperature of the outer layer of the silk cake produced on the hot roller in the hot box, δ 1 is the heat transfer distance between the hot roller and the wire, i.e. the thickness of the wire;

[0034] During stable production, the heat transferred from the wire to the air in the heat box is:

[0035] (Formula 2);

[0036] Among them, λ 2 is the thermal conductivity of the air in the hot box, F 2 is the contact area between the wire and the air in the hot box, T s is the temperature of the yarn on the hot roller when producing the outer layer of the yarn cake, δ 2 It is the heat transfer distance between the wire and the air in the heat box, that is, the thickness of the air.

[0037] Hot roller temperature T GR Rise to the hot roller process temperature HT and the hot roller heating compensation temperature T b The heat transferred by the hot roller to the wire in the Kth second after the sum is:

[0038] (Formula 3);

[0039] Hot roller temperature T GR Rise to the hot roller process temperature HT and the hot roller heating compensation temperature T b The heat transferred by the wire to the air in the Kth second after the sum is:

[0040] (Formula 4);

[0041] Among them, T c is the temperature of the hot roller T GR Rise to the hot roller process temperature HT and the hot roller heating compensation temperature T b The ambient temperature of the hot box K seconds after the sum of

[0042] Therefore, when Q 3 -Q 1 The hot roller temperature T GR Rise to the hot roller process temperature HT and the hot roller heating compensation temperature T b The heat compensation of the hot roller to the wire at the Kth second after the sum of 4 -Q 2 It can be obtained that the temperature of the hot roller is T GR Rise to the hot roller process temperature HT and the hot roller heating compensation temperature T b The sum of the heat lost to the air by the silk at the Kth second after the start of production compared to the heat lost during stable production.

[0043] The heat compensated by the hot roller to the wire is consistent with the heat lost by the wire to the air. Therefore, Q 3 -Q 1 = Q 4 -Q 2 ,Right now:

[0044] (Formula 5);

[0045] It can be further known that the compensation temperature of the hot roller is reduced to T b’ , the ambient temperature of the hot box rises to T, we can get:

[0046] (Formula 6);

[0047] By eliminating the constants in the formulas (Equation 6) and (Equation 5), we can obtain:

[0048] (Formula 7);

[0049] From (Equation 7), we can see that (T - T c ) / (T 0 -T c ) is the rate of change of the ambient temperature of the hot box, T b -[(T – Tc ) / (T 0 -T c )] *T b is the value of the compensation temperature that decreases at the same rate of change;

[0050] In summary, "heat roller heating compensation temperature T b The derivation process of "the cooling rate needs to be the same as the heating rate of the hot box environment" is completed.

[0051] In (Equation 5), the unknown quantity is T b and T c , while T c is the temperature of the hot roller T GR Rise to the hot roller process temperature HT and the hot roller heating compensation temperature T b The ambient temperature of the hot box at the Kth second after the sum of the values, where the Kth second is within the period from the start of the first switching to the start of the second switching;

[0052] T b The method for obtaining the temperature T can be as follows: First, the heating compensation temperature T of the hot roller is not set. b The ambient temperature of the hot box when the first switching starts is T 1 (Since the hot roller temperature T is set during one switching process GR The value is equal to the hot roller process temperature HT and the hot roller heating compensation temperature T b Therefore, the heating compensation temperature T of the hot roller is not set. b The ambient temperature of the hot box when the first switching starts is T 1 , and set the heating roller heating compensation temperature T b The ambient temperature of the hot box when the first switching starts is T x The value is the same), and then the heating compensation temperature T of the hot roller is not set. b The hot box ambient temperature T when the secondary switching starts 2 , take T 1 to T 2 Any value between c In T 1 With T x Under the same circumstances, the time from the start of the first switch to the start of the second switch does not change, so the heating roller heating compensation temperature T is set. b The hot box ambient temperature T at the start of the secondary switching y The value of must be greater than T 2 , that is, the T c Must be in T x With T y Between. Take the T c Substituting into (Equation 5) we can calculate the corresponding T b In this T bUnder this condition, the time point when the ambient temperature of the heat box and the temperature of the hot roller just reach equilibrium (that is, the time point when the heat compensated by the hot roller to the silk is just the same as the heat lost by the silk to the air) must be within the period from the start of the first switch to the start of the second switch, so that before the end of the second switch, the quality of the silk can be the same as the quality of the outer layer of the silk cake.

[0053] Theoretically, the ambient temperature of the hot box and the temperature of the hot roller can be balanced during the secondary switching process, but there will be problems in the actual operation process, that is, when the ambient temperature of the hot box and the temperature of the hot roller just reach equilibrium, some poor quality silk (non-stable production silk) is still between the hot box and the winding machine, and with the secondary switching, it is wound on the silk tube as the bottom silk. The process of the primary switching and the secondary switching is 5~10s, the winding speed is greater than 60m / s, and the distance from the hot box to the winding is 3m. Therefore, the present invention will start to reduce the temperature T of the hot roller. GR The time point is controlled at the beginning of the secondary switching and before the secondary switching, so that when the ambient temperature of the hot box and the temperature of the hot roller just reach equilibrium, some of the poor quality silk (silk produced unstably) will be wound onto the switched waste rolls during the secondary switching process, so that the silk after the secondary switching is all silk produced after reaching stability.

[0054] In the spinning process for improving the quality of polyester FDY bottom yarn as described above, the ambient temperature in the heat box is 25-50°C when the hot roller is started, the time from starting the hot roller to the start of one switching is 5-10 minutes, the time for one switching is 5-10 seconds, the time from the end of one switching to the start of a second switching is 50-90 seconds, and the time for the second switching is 5-10 seconds.

[0055] In the spinning-in process for improving the quality of polyester FDY bottom yarn as described above, a temperature sensor is provided in the hot box, and the temperature sensor measures the hot box ambient temperature in real time; the central value T of the hot box ambient temperature 0 For producing the outer layer of the yarn cake, 1 The average value of the hot box ambient temperature during the time period, t 1 The duration of the time period is 30-60 minutes.

[0056] In the spinning process for improving the quality of polyester FDY bottom yarn as described above, the temperature sensor is a PT100 probe temperature sensor, and the installation position is 5-10 cm away from the yarn outlet; part of the hot air in the heat box will flow out of the heat box along with the yarn bundle, affecting the temperature around the yarn outlet, and it will be affected if it is too close to the yarn outlet, and when the distance is greater than 10 cm, it is close to the hot roller and is easily affected by the temperature of the hot roller.

[0057] A spinning process for improving the quality of polyester FDY bottom layer yarn as described in any of the above items, wherein the fineness of the FDY bottom layer yarn spun is 50-350dtex, the hairy yarn rate is 0.30-0.55%, the yarn unevenness CV% is not higher than 0.7%, the elongation at break is 27-35%, and the relative deviation from the elongation at break of the outer layer yarn of the yarn cake is less than 3%, and the boiling water shrinkage is 6.6-8.0%, and the relative deviation from the boiling water shrinkage of the outer layer yarn of the yarn cake is less than 3%.

[0058] The spinning process for improving the quality of polyester FDY bottom yarn as described above comprises the following process parameters during spinning: winding speed 3800-5300 m / min, hot roller process temperature HT 75-135°C, ambient temperature in the hot box 25-50°C when starting the hot roller, hot roller speed 1800-5400 m / min, and oiling rate 0.8-1.2wt%.

[0059] Beneficial Effects

[0060] The invention discloses a spinning process for improving the quality of polyester FDY bottom yarn, by continuously adjusting the temperature T of the hot roller. GR , so that after the second switching starts, when the silk passes through the heat box where the hot roller is located, the temperature of the silk on the hot roller is always the same, thereby ensuring that the quality of the bottom layer silk produced is the same as the quality of the outer layer silk of the silk cake. BRIEF DESCRIPTION OF THE DRAWINGS

[0061] Figure 1 The temperature-time variation curve of the ambient temperature of the hot box returning to a stable value after the second switching is completed when heating compensation is not performed;

[0062] Figure 2 is the temperature of the hot roller T GR Curve graph of changes over time; where ① is the time to stop the hot roller operation and heating; ② is the time to start the hot roller spinning; ③ is the time period of a switch; ④ is the hot roller temperature T GR Achieve HT+T b After K seconds, the ambient temperature of the hot box reaches T c ⑤ is the time period of the secondary switching; ⑧ is the temperature of the hot roller T GR Time to return to HT;

[0063] Figure 3 is a curve diagram of the change of the ambient temperature of the hot box over time; among them, ① is the time to stop the operation and heating of the hot roller; ② is the time to start the hot roller; ③ is the time period of one switching; ④ is the temperature T of the hot roller GR Achieve HT+T b After K seconds, the ambient temperature of the hot box reaches T c ⑤ is the time period for the secondary switching; ⑥ is the time period for the ambient temperature of the hot box to return to T 0⑦ is the time for measuring the center value of the hot box ambient temperature T 0 Time period t 1 . DETAILED DESCRIPTION

[0064] The present invention will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and are not intended to limit the scope of the present invention. In addition, it should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms fall within the scope limited by the appended claims of the application equally.

[0065] The test method involved in the present invention is as follows:

[0066] Denier: Refer to GB / T 14343-2008 Test method for linear density of chemical fiber filaments;

[0067] Hair rate: refer to "Q / 320584 NPA008-2022 Polyester Super Bright Drawn Yarn Appearance Items and Indicators";

[0068] CV% of yarn unevenness: refer to GB / T 14346-2015 Test method for yarn unevenness of chemical filament yarn - capacitance method;

[0069] Elongation at break: refer to GB / T 14344-2022 Test method for tensile properties of chemical fiber filaments;

[0070] Boiling water shrinkage: refer to "GB / T 6505-2017 Test method for thermal shrinkage of chemical fiber filaments".

[0071] A spinning-in process for improving the quality of polyester FDY bottom yarn, the specific process is as follows:

[0072] Set the hot roller temperature T during one switching process GR The value is equal to the hot roller process temperature HT and the hot roller heating compensation temperature T b The sum of the two switchings is used for spinning after the second switching. The hot roller process temperature HT is the hot roller temperature when producing the outer layer of the silk cake. T b satisfy:

[0073]

[0074] Among them, λ 2 is the thermal conductivity of the air in the hot box, F 2 is the contact area between the wire and the air in the hot box, δ 2 is the heat transfer distance between the wire and the air in the hot box, λ 1 is the thermal conductivity of the wire, F 1 is the contact area between the wire and the hot roller, δ 1is the heat transfer distance between the hot roller and the wire, T c is the temperature of the hot roller T GR Rise to the hot roller process temperature HT and the hot roller heating compensation temperature T b The ambient temperature of the hot box at the Kth second after the sum of the values ​​of T and T, where the Kth second is within the period from the start of the first switching to the start of the second switching; 0 is the central value of the hot box environment temperature, which is the value of the outer layer of the silk cake when producing the silk cake. 1 The average value of the hot box ambient temperature during the time period, t 1 The duration of the time period is 30-60 minutes;

[0075] Among them, the temperature of the hot roller is T GR Rise to the hot roller process temperature HT and the hot roller heating compensation temperature T b After the sum, wait for a while until the ambient temperature of the hot box is equal to T c When the heating compensation temperature T of the hot roller is reduced at the same rate according to the rate of increase of the hot box ambient temperature, b until the ambient temperature of the hot box is equal to the central value of the ambient temperature of the hot box T 0 , hot roller temperature T GR Equal to the hot roller process temperature HT;

[0076] A PT100 probe temperature sensor is installed in the hot box, and the installation distance from the wire outlet is 5-10cm; the PT100 probe temperature sensor measures the hot box ambient temperature in real time;

[0077] like Figure 2 and Figure 3 The figure shows the temperature T of the hot roller inside the hot box and during the process from the hot roller stopping and cleaning to the spinning process. GR The curve graph of the change with time and the curve graph of the change with time of the hot box ambient temperature; ① is the time to stop the operation and heating of the hot roller. Before reaching ①, the hot roller temperature is the hot roller process temperature HT, and the hot box ambient temperature is equal to the hot box ambient temperature center value T 0 ; ② is the start-up time of the hot roller. Before reaching ② from ①, the temperature of the hot roller is decreasing, and the ambient temperature of the hot box is also decreasing; ③ is the time period of a switch. Since the hot roller starts to heat at ②, the temperature of the hot roller and the ambient temperature of the hot box are both increasing during the process from ② to the start of a switch; ④ is the temperature T of the hot roller. GR Achieve HT+T b After K seconds, the ambient temperature of the hot box reaches T c time, since the hot roller temperature T is set during a switching process GR Equal to HT+T b, the temperature of the hot roller and the ambient temperature of the hot box are both increasing, and at ④, the temperature of the hot roller and the ambient temperature of the hot box satisfy (Formula 5), ​​that is, the heat compensated by the hot roller for the wire is consistent with the heat lost to the air by the wire; afterwards, due to the real-time increase rate according to the ambient temperature of the hot box in the spinning process, the heating compensation temperature T of the hot roller is reduced at the same rate at the same time b until the ambient temperature of the hot box is equal to the central value of the ambient temperature of the hot box T 0 , the second hot roller temperature T GR =Equal to the second hot roller process temperature HT, therefore, it can be seen from the figure that the heating rate of the hot box ambient temperature and the hot roller heating compensation temperature T b The cooling rate is the same; in the process of cooling the hot roller, a second switch is completed; ⑥ is the temperature of the hot box is restored to T 0 ⑦ is the time for measuring the center value of the hot box ambient temperature T 0 Time period t 1 ⑧ is the temperature of the hot roller T GR The time to recover to HT; due to the simultaneous reduction of the hot roller heating compensation temperature T at the same rate b until the ambient temperature of the hot box is equal to the central value of the ambient temperature of the hot box T 0 , the hot roller temperature TGR is equal to the hot roller process temperature HT, therefore, the time represented by ⑥ and ⑧ has the same value.

[0078] The following uses specific embodiments to specifically illustrate the technical solution of the present application:

[0079] Example 1

[0080] A spinning-in process for improving the quality of polyester FDY bottom yarn, after the first hot roller inside the first hot box and the first hot roller inside are cleaned (the second hot box and the second hot roller inside are not stopped for cleaning), the following operations are performed:

[0081] (1) Determine production goals and spinning process parameters;

[0082] The production target is polyester FDY products (multifilament fineness is 50dtex);

[0083] The spinning process parameters include: winding speed 5150 m / min, second hot roller process temperature HT 120 °C, first hot roller speed 3800 m / min, second hot roller speed 5220 m / min, oiling rate 1.20 wt%;

[0084] (2) Conduct simulation experiments to determine the first hot roller heating compensation temperature T b ;

[0085] (a) When the second hot box is not stopped (the temperature of the second hot roller is T GR= equal to the second hot roller process temperature HT), set the first hot roller temperature T GR The value is equal to the first hot roller process temperature HT, which is 75°C. The first hot roller is started. At this time, the ambient temperature of the first hot box is 25°C.

[0086] (b) After starting the first hot roller, wait for 6 minutes to start the first switch, which takes 5 seconds. After the first switch, wait for 50 seconds to start the second switch, which takes 5 seconds. After the second switch, spinning is carried out according to the spinning process parameters of step (1);

[0087] In this process, the first hot box ambient temperature T is obtained at the beginning of a switch. 1 , the first hot box ambient temperature T at the beginning of the second switching 2 , the contact area between the wire and the air in the first heat box F 2 , heat transfer distance between the wire and the air in the first heat box δ 2 , the contact area between the wire and the first hot roller F 1 , heat transfer distance between the first hot roller and the wire δ 1 , the center value of the first hot box ambient temperature T 0 ; Among them, the center value of the first hot box ambient temperature T 0 For producing the outer layer of the yarn cake, 1 The average value of the hot box ambient temperature during the time period, t 1 The duration of the time period is 30 minutes;

[0088] T 1 is 63.4℃; T 2 65.5℃; F 2 =7.57×10 -4 m 2 ; δ 2 =0.425m; F 1 =1.2×10 -4 m 2 ; δ 1 =0.027mm; T 0 70.1℃;

[0089] In step (a) to step (b), the ambient temperature of the first hot box is measured in real time by a PT100 probe temperature sensor provided in the first hot box, and the installation position of the PT100 probe temperature sensor is 5 cm away from the wire outlet;

[0090] (c) According to T 1 and T 2 , select 65.0℃ as T c ;

[0091] (d) Calculate the first hot roller heating compensation temperature T according to the following formula: b, is 0.78℃;

[0092]

[0093] Among them, λ 1 is the thermal conductivity of the wire, λ 1 =0.084 W / m·k; λ 2 is the thermal conductivity of the air in the first heat box, λ 2 =0.032W / m·k;

[0094] (3) Actual production operations;

[0095] (I) When the second hot box is not stopped (the second hot roller temperature TGR is equal to the second hot roller process temperature HT), set the first hot roller temperature T GR The value is equal to the first hot roller process temperature HT, and the first hot roller is started. At this time, the ambient temperature of the first hot box is 25℃;

[0096] (II) After starting the first hot roller, wait for 6 minutes before starting a switch, and set the first hot roller temperature T at the beginning of a switch. GR The value is equal to the first hot roller process temperature HT and the first hot roller heating compensation temperature T b The sum of the switching time is 5 seconds. After the first switching, wait for 50 seconds before starting the second switching. The second switching time is 5 seconds. After the second switching, spinning is carried out according to the spinning process parameters of step (1);

[0097] When the ambient temperature of the first heat box is equal to T c When the first heat box environment temperature is increased in real time, the first heat roller heating compensation temperature T is reduced at the same rate. b until the first hot box ambient temperature is equal to the first hot box ambient temperature center value T 0 , the first hot roller temperature T GR Equal to the first hot roller process temperature HT.

[0098] The final spun FDY bottom layer yarn had a fineness of 50.0 dtex, a hairy yarn rate of 0.55%, a yarn unevenness rate CV% of 0.66%, an elongation at break of 35.0%, which was 1.23% relative to the elongation at break of the outer layer yarn of the yarn cake, and a boiling water shrinkage of 7.2%, which was 1.31% relative to the boiling water shrinkage of the outer layer yarn of the yarn cake.

[0099] Example 2

[0100] A spinning-in process for improving the quality of polyester FDY bottom yarn, after the first hot roller inside the first hot box and the first hot roller inside are cleaned (the second hot box and the second hot roller inside are not stopped for cleaning), the following operations are performed:

[0101] (1) Determine production goals and spinning process parameters;

[0102] The production target is polyester FDY products (multifilament fineness is 83dtex);

[0103] The spinning process parameters include: winding speed 5300 m / min, second hot roller process temperature HT 123 °C, first hot roller speed 3900 m / min, second hot roller speed 5400 m / min, oiling rate 0.96 wt%;

[0104] (2) Conduct simulation experiments to determine the first hot roller heating compensation temperature T b ;

[0105] (a) When the second hot box is not stopped (the temperature of the second hot roller is T GR = equal to the second hot roller process temperature HT), set the first hot roller temperature T GR The value is equal to the first hot roller process temperature HT, which is 82°C. The first hot roller is started. At this time, the ambient temperature of the first hot box is 35°C.

[0106] (b) After starting the first hot roller, wait for 5 minutes to start the first switch, which takes 5 seconds. After the first switch, wait for 60 seconds to start the second switch, which takes 5 seconds. After the second switch, spinning is carried out according to the spinning process parameters of step (1);

[0107] In this process, the first hot box ambient temperature T is obtained at the beginning of a switch. 1 , the first hot box ambient temperature T at the beginning of the second switching 2 , the contact area between the wire and the air in the first heat box F 2 , heat transfer distance between the wire and the air in the first heat box δ 2 , the contact area between the wire and the first hot roller F 1 , heat transfer distance between the first hot roller and the wire δ 1 , the center value of the first hot box ambient temperature T 0 ; Among them, the center value of the first hot box ambient temperature T 0 For producing the outer layer of the yarn cake, 1 The average value of the hot box ambient temperature during the time period, t 1 The duration of the time period is 30 minutes;

[0108] T 1 is 62.2℃; T 2 64.7℃; F 2 =8.73×10 -4 m 2 ; δ 2 =0.425m; F 1 =1.39×10-4 m 2 ; δ 1 =0.0346mm; T 0 is 75.8℃;

[0109] In step (a) to step (b), the ambient temperature of the first hot box is measured in real time by a PT100 probe temperature sensor provided in the first hot box, and the installation position of the PT100 probe temperature sensor is 10 cm away from the wire outlet;

[0110] (c) According to T 1 and T 2 , select 64.0℃ as T c ;

[0111] (d) Calculate the first hot roller heating compensation temperature T according to the following formula: b , is 2.30℃;

[0112]

[0113] Among them, λ 1 is the thermal conductivity of the wire, λ 1 =0.084 W / m·k; λ 2 is the thermal conductivity of the air in the first heat box, λ 2 =0.032W / m·k;

[0114] (3) Actual production operations;

[0115] (I) When the second hot box is not stopped (the second hot roller temperature TGR is equal to the second hot roller process temperature HT), set the first hot roller temperature T GR The value is equal to the first hot roller process temperature HT, and the first hot roller is started. At this time, the ambient temperature of the first hot box is 35℃;

[0116] (II) After starting the first hot roller, wait for 5 minutes before starting a switch, and set the first hot roller temperature T at the beginning of a switch. GR The value is equal to the first hot roller process temperature HT and the first hot roller heating compensation temperature T b The sum of the switching time is 5 seconds. After the first switching, wait for 60 seconds before starting the second switching. The second switching time is 5 seconds. After the second switching, spinning is carried out according to the spinning process parameters of step (1);

[0117] When the ambient temperature of the first heat box is equal to T c When the first heat box environment temperature is increased in real time, the first heat roller heating compensation temperature T is reduced at the same rate. b until the first hot box ambient temperature is equal to the first hot box ambient temperature center value T0 , the first hot roller temperature T GR Equal to the first hot roller process temperature HT.

[0118] The final spun FDY bottom layer yarn had a fineness of 83.1 dtex, a hairy yarn rate of 0.30%, a yarn unevenness rate CV% of 0.53%, an elongation at break of 33.5%, which was 1.78% relative to the elongation at break of the outer layer yarn of the yarn cake, and a boiling water shrinkage of 7.2%, which was 2.31% relative to the boiling water shrinkage of the outer layer yarn of the yarn cake.

[0119] Example 3

[0120] A spinning-in process for improving the quality of polyester FDY bottom yarn, after the second hot roller inside the second hot box and the second hot roller inside are cleaned (the first hot box and the first hot roller inside are not stopped for cleaning), the following operations are performed:

[0121] (1) Determine production goals and spinning process parameters;

[0122] The production target is polyester FDY products (multifilament fineness is 83dtex);

[0123] The spinning process parameters include: winding speed 5000 m / min, first hot roller process temperature HT 92°C, first hot roller speed 2100 m / min, second hot roller speed 5070 m / min, oiling rate 0.85 wt%;

[0124] (2) Conduct simulation experiments to determine the second hot roller heating compensation temperature T b ;

[0125] (a) When the first hot box is not stopped (the temperature of the first hot roller is T GR = equal to the first hot roller process temperature HT), set the second hot roller temperature T GR The value is equal to the second hot roller process temperature HT, which is 129°C. The second hot roller is started. At this time, the ambient temperature of the second hot box is 42°C.

[0126] (b) After starting the second hot roller, wait for 10 minutes to start the first switch, which takes 5 seconds. After the first switch, wait for 75 seconds to start the second switch, which takes 5 seconds. After the second switch, spinning is carried out according to the spinning process parameters of step (1);

[0127] In this process, the ambient temperature T of the second hot box at the beginning of a switch is obtained. 1 , the second hot box ambient temperature T at the start of the second switching 2 , the contact area between the wire and the air in the second heat box F 2 , heat transfer distance between the wire and the air in the second heat box δ 2, the contact area between the wire and the second hot roller F 1 , heat transfer distance between the second hot roller and the wire δ 1 , the second heat box ambient temperature center value T 0 ; Among them, the second hot box ambient temperature center value T 0 For producing the outer layer of the yarn cake, 1 The average value of the hot box ambient temperature during the time period, t 1 The duration of the time period is 40 minutes;

[0128] T 1 105.5℃; T 2 108.4℃; F 2 =9.93×10 -4 m 2 ; δ 2 =0.425m; F 1 =1.58×10 -4 m 2 ; δ 1 =0.0218mm; T 0 120.4℃;

[0129] In step (a) to step (b), the ambient temperature of the second hot box is measured in real time by a PT100 probe temperature sensor provided in the second hot box, and the installation position of the PT100 probe temperature sensor is 10 cm away from the wire outlet;

[0130] (c) According to T 1 and T 2 , select 108℃ as T c ;

[0131] (d) Calculate the second hot roller heating compensation temperature T according to the following formula: b , is 1.52℃;

[0132]

[0133] Among them, λ 1 is the thermal conductivity of the wire, λ 1 =0.084 W / m·k; λ 2 is the thermal conductivity of the air in the second heat box, λ 2 =0.032W / m·k;

[0134] (3) Actual production operations;

[0135] (I) When the first hot box is not shut down (the first hot roller temperature TGR is equal to the first hot roller process temperature HT), set the second hot roller temperature T GRThe value is equal to the second hot roller process temperature HT, and the second hot roller is started. At this time, the ambient temperature of the second hot box is 42°C;

[0136] (II) After starting the second hot roller, wait for 10 minutes before starting a switch, and set the second hot roller temperature T at the beginning of a switch. GR The value is equal to the second hot roller process temperature HT and the second hot roller heating compensation temperature T b The sum of the switching time is 5 seconds. After the first switching, wait for 75 seconds before starting the second switching. The second switching time is 5 seconds. After the second switching, spinning is carried out according to the spinning process parameters of step (1);

[0137] When the ambient temperature of the second heat box is equal to T c When the temperature of the second hot box is increased in real time, the second hot roller heating compensation temperature T is reduced at the same rate. b until the second hot box ambient temperature is equal to the second hot box ambient temperature center value T 0 , the second hot roller temperature T GR Equal to the second hot roller process temperature HT.

[0138] The final spun FDY bottom layer yarn had a fineness of 83.4 dtex, a hairy yarn rate of 0.48%, a yarn unevenness rate CV% of 0.70%, an elongation at break of 34.9%, which was 1.48% relative to the elongation at break of the outer layer yarn of the yarn cake, and a boiling water shrinkage of 7.3%, which was 1.63% relative to the boiling water shrinkage of the outer layer yarn of the yarn cake.

[0139] Example 4

[0140] A spinning-in process for improving the quality of polyester FDY bottom yarn, after the second hot roller inside the second hot box and the second hot roller inside are cleaned (the first hot box and the first hot roller inside are not stopped for cleaning), the following operations are performed:

[0141] (1) Determine production goals and spinning process parameters;

[0142] The production target is polyester FDY products (multifilament fineness is 167dtex);

[0143] The spinning process parameters include: winding speed 3800 m / min, first hot roller process temperature HT 98 °C, first hot roller speed 1800 m / min, second hot roller speed 3900 m / min, oiling rate 0.80 wt%;

[0144] (2) Conduct simulation experiments to determine the second hot roller heating compensation temperature T b ;

[0145] (a) When the first hot box is not stopped (the temperature of the first hot roller is T GR = equal to the first hot roller process temperature HT), set the second hot roller temperature T GR The value is equal to the second hot roller process temperature HT, which is 130°C. The second hot roller is started to spin up. At this time, the ambient temperature of the second hot box is 50°C.

[0146] (b) After starting the second hot roller, wait for 8 minutes to start the first switch, which takes 5 seconds. After the first switch, wait for 90 seconds to start the second switch, which takes 5 seconds. After the second switch, spinning is carried out according to the spinning process parameters of step (1);

[0147] In this process, the ambient temperature T of the second hot box at the beginning of a switch is obtained. 1 , the second hot box ambient temperature T at the start of the second switching 2 , the contact area between the wire and the air in the second heat box F 2 , heat transfer distance between the wire and the air in the second heat box δ 2 , the contact area between the wire and the second hot roller F 1 , heat transfer distance between the second hot roller and the wire δ 1 , the second heat box ambient temperature center value T 0 ; Among them, the second hot box ambient temperature center value T 0 For producing the outer layer of the yarn cake, 1 The average value of the hot box ambient temperature during the time period, t 1 The duration of the time period is 60 minutes;

[0148] T 1 98.4℃; T 2 102.9℃; F 2 =1.51×10 -3 m 2 ; δ 2 =0.425m; F 1 =2.41×10 -4 m 2 ; δ 1 =0.0265mm; T 0 120.7℃;

[0149] In step (a) to step (b), the ambient temperature of the second hot box is measured in real time by a PT100 probe temperature sensor provided in the second hot box, and the installation position of the PT100 probe temperature sensor is 8 cm away from the wire outlet;

[0150] (c) According to T 1 and T 2 , select 102℃ as T c ;

[0151] (d) Calculate the second hot roller heating compensation temperature T according to the following formula: b , is 2.78℃;

[0152]

[0153] Among them, λ 1 is the thermal conductivity of the wire, λ 1 =0.084 W / m·k; λ 2 is the thermal conductivity of the air in the second heat box, λ 2 =0.032W / m·k;

[0154] (3) Actual production operations;

[0155] (I) When the first hot box is not shut down (the first hot roller temperature TGR is equal to the first hot roller process temperature HT), set the second hot roller temperature T GR The value is equal to the second hot roller process temperature HT, and the second hot roller is started. At this time, the ambient temperature of the second hot box is 50℃;

[0156] (II) After starting the second hot roller, wait for 8 minutes before starting a switch, and set the second hot roller temperature T at the beginning of a switch. GR The value is equal to the second hot roller process temperature HT and the second hot roller heating compensation temperature T b The sum of the switching time is 5 seconds. After the first switching, wait for 90 seconds before starting the second switching. The second switching time is 5 seconds. After the second switching, spinning is carried out according to the spinning process parameters of step (1);

[0157] When the ambient temperature of the second heat box is equal to T c When the temperature of the second hot box is increased in real time, the second hot roller heating compensation temperature T is reduced at the same rate. b until the second hot box ambient temperature is equal to the second hot box ambient temperature center value T 0 , the second hot roller temperature T GR Equal to the second hot roller process temperature HT.

[0158] The final spun FDY bottom layer yarn had a fineness of 167.3 dtex, a hairy yarn rate of 0.37%, a yarn unevenness rate CV% of 0.62%, an elongation at break of 27.0%, which was 1.59% relative to the elongation at break of the outer layer yarn of the yarn cake, and a boiling water shrinkage of 6.6%, which was 2.17% relative to the boiling water shrinkage of the outer layer yarn of the yarn cake.

[0159] Example 5

[0160] A spinning-in process for improving the quality of polyester FDY bottom yarn, after the second hot roller inside the second hot box and the second hot roller inside are cleaned (the first hot box and the first hot roller inside are not stopped for cleaning), the following operations are performed:

[0161] (1) Determine production goals and spinning process parameters;

[0162] The production target is polyester FDY products (multifilament fineness is 350dtex);

[0163] The spinning process parameters include: winding speed 4600 m / min, first hot roller process temperature HT 103 °C, first hot roller speed 2000 m / min, second hot roller speed 4700 m / min, oiling rate 0.90 wt%;

[0164] (2) Conduct simulation experiments to determine the second hot roller heating compensation temperature T b ;

[0165] (a) When the first hot box is not stopped (the temperature of the first hot roller is T GR = equal to the first hot roller process temperature HT), set the second hot roller temperature T GR The value is equal to the second hot roller process temperature HT, which is 135°C. The second hot roller is started to spin up. At this time, the ambient temperature of the second hot box is 46°C.

[0166] (b) After starting the second hot roller, wait for 8 minutes to start the first switch, which takes 5 seconds. After the first switch, wait for 60 seconds to start the second switch, which takes 5 seconds. After the second switch, spinning is carried out according to the spinning process parameters of step (1);

[0167] In this process, the ambient temperature T of the second hot box at the beginning of a switch is obtained. 1 , the second hot box ambient temperature T at the start of the second switching 2 , the contact area between the wire and the air in the second heat box F 2 , heat transfer distance between the wire and the air in the second heat box δ 2 , the contact area between the wire and the second hot roller F 1 , heat transfer distance between the second hot roller and the wire δ 1 , the second heat box ambient temperature center value T 0 ; Among them, the second hot box ambient temperature center value T 0 For producing the outer layer of the yarn cake, 1 The average value of the hot box ambient temperature during the time period, t 1 The duration of the time period is 60 minutes;

[0168] T 1 is 106.7℃; T 2 110.1℃; F 2=1.62×10 -3 m 2 ; δ 2 =0.425m; F 1 =2.58×10 -4 m 2 ; δ 1 =0.0296mm; T 0 122.8℃;

[0169] In step (a) to step (b), the ambient temperature of the second hot box is measured in real time by a PT100 probe temperature sensor provided in the second hot box, and the installation position of the PT100 probe temperature sensor is 8 cm away from the wire outlet;

[0170] (c) According to T 1 and T 2 , select 109.5℃ as T c ;

[0171] (d) Calculate the second hot roller heating compensation temperature T according to the following formula: b , is 2.22℃;

[0172]

[0173] Among them, λ 1 is the thermal conductivity of the wire, λ 1 =0.084 W / m·k; λ 2 is the thermal conductivity of the air in the second heat box, λ 2 =0.032W / m·k;

[0174] (3) Actual production operations;

[0175] (I) When the first hot box is not shut down (the first hot roller temperature TGR is equal to the first hot roller process temperature HT), set the second hot roller temperature T GR The value is equal to the second hot roller process temperature HT, and the second hot roller is started. At this time, the ambient temperature of the second hot box is 46°C;

[0176] (II) After starting the second hot roller, wait for 8 minutes before starting a switch, and set the second hot roller temperature T at the beginning of a switch. GR The value is equal to the second hot roller process temperature HT and the second hot roller heating compensation temperature T b The sum of the switching time is 5 seconds. After the first switching, wait for 60 seconds before starting the second switching. The second switching time is 5 seconds. After the second switching, spinning is carried out according to the spinning process parameters of step (1);

[0177] When the ambient temperature of the second heat box is equal to T cWhen the temperature of the second hot box is increased in real time, the second hot roller heating compensation temperature T is reduced at the same rate. b until the second hot box ambient temperature is equal to the second hot box ambient temperature center value T 0 , the second hot roller temperature T GR Equal to the second hot roller process temperature HT.

[0178] The final spun FDY bottom layer yarn had a fineness of 349.9 dtex, a hairy yarn rate of 0.47%, a yarn unevenness rate CV% of 0.68%, an elongation at break of 30.6%, which was 2.05% relative to the elongation at break of the outer layer yarn of the yarn cake, and a boiling water shrinkage of 8.0%, which was 2.36% relative to the boiling water shrinkage of the outer layer yarn of the yarn cake.

Claims

1. A spinning-in process for improving the quality of polyester FDY bottom yarn, characterized in that: By constantly adjusting the temperature T of the hot roller GR , so that after the secondary switching starts, when the silk passes through the heat box where the heat roller is located, the temperature of the silk on the heat roller is always the same; Set the hot roller temperature T during one switching process GR The value is equal to the hot roller process temperature HT and the hot roller heating compensation temperature T b The sum of the two switchings is used for spinning after the second switching. The hot roller process temperature HT is the hot roller temperature when producing the outer layer of the silk cake. T b satisfy: Among them, λ2 is the thermal conductivity of the air in the hot box, F2 is the contact area between the wire and the air in the hot box, δ2 is the heat transfer distance between the wire and the air in the hot box, that is, the thickness of the air, λ1 is the thermal conductivity of the wire, F1 is the contact area between the wire and the hot roller, δ1 is the heat transfer distance between the hot roller and the wire, that is, the thickness of the wire, T c is the temperature of the hot roller T GR Rise to the hot roller process temperature HT and the hot roller heating compensation temperature T b The ambient temperature of the hot box at the Kth second after the sum of the values, where the Kth second is within the period from the start of the first switching to the start of the second switching; Among them, the temperature of the hot roller is T GR Rise to the hot roller process temperature HT and the hot roller heating compensation temperature T b After the sum, wait for a while until the ambient temperature of the hot box is equal to T c When the heating rate is increased in real time according to the ambient temperature of the hot box, the heating compensation temperature T of the hot roller is reduced at the same rate. b until the temperature of the hot box environment is equal to the center value of the hot box environment temperature T0, and the temperature of the hot roller T GR It is equal to the hot roller process temperature HT; the center value of the hot box ambient temperature T0 is the average value of the hot box ambient temperature when producing the outer layer of the silk cake.

2. A spinning-in process for improving the quality of polyester FDY bottom yarn according to claim 1, characterized in that: When starting the hot roller, the ambient temperature in the hot box is 25-50℃. The time from starting the hot roller to the start of the first switch is 5-10 minutes, and the time for the first switch is 5-10 seconds. The time from the end of the first switch to the start of the second switch is 50-90 seconds, and the time for the second switch is 5-10 seconds.

3. A spinning-in process for improving the quality of polyester FDY bottom yarn according to claim 1, characterized in that: A temperature sensor is provided in the hot box, which measures the hot box ambient temperature in real time; the hot box ambient temperature center value T0 is the average value of the hot box ambient temperature in the t1 time period when producing the outer layer of the silk cake, and the duration of the t1 time period is 30-60 minutes.

4. A spinning-in process for improving the quality of polyester FDY bottom yarn according to claim 3, characterized in that: The temperature sensor is a PT100 probe temperature sensor, and the installation distance between the installation position and the wire outlet is 5-10cm.

5. A spinning-in process for improving the quality of polyester FDY bottom yarn according to any one of claims 1 to 4, characterized in that: The fineness of the FDY bottom layer yarn produced by spinning is 50-350dtex, the hairy yarn rate is 0.30-0.55%, the yarn unevenness rate CV% is not higher than 0.7%, the elongation at break is 27-35%, and the relative deviation from the elongation at break of the outer layer yarn of the yarn cake is less than 3%, and the boiling water shrinkage is 6.6-8.0%, and the relative deviation from the boiling water shrinkage of the outer layer yarn of the yarn cake is less than 3%.

6. A spinning-in process for improving the quality of polyester FDY bottom yarn according to claim 5, characterized in that: The process parameters during spinning include: winding speed 3800-5300 m / min, hot roller process temperature HT 75-135° C., hot roller speed 1800-5400 m / min, and oiling rate 0.8-1.2 wt %.

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