Method for improving dyeing uniformity of oil-free drafted FDY (Fully Drawn Yarn) fiber

Abstract

The invention belongs to the technical field of polyester filament yarns, and discloses a method for improving dyeing uniformity of oil-free drafted FDY (fully drawn yarn) fiber, which comprises the following steps of: detecting the pressure of yarns born by a first U-shaped porcelain piece in real time by using a pressure sensor, and determining the dyeing uniformity of the oil-free drafted FDY fiber by comparing a pressure setting range with a received pressure value; and the displacement of the second U-shaped porcelain piece is controlled according to a comparison result, so that the angle of the tow passing through the two U-shaped porcelain pieces is changed, and the pressure of the tow borne by the first U-shaped porcelain piece returns to a set range. According to the invention, the tension change of the tow in the production process can be monitored in real time, and the tension change of the tow can be accurately adjusted in real time according to the detected pressure value, so that the problem of poor dyeing caused by the tension change in the production process is avoided.

Description

Technical Field

[0001] The present invention belongs to the technical field of polyester filaments and relates to a method for improving the dyeing uniformity of oil-free drawn FDY fibers. Background Art

[0002] Polyester drawn yarn (FDY) is a fully drawn yarn produced by a one-step process of spinning, drawing and setting. Because it has undergone the drawing and setting processes during production, the fiber has a relatively high breaking strength and an appropriate elongation at break, and can be directly used for weaving, so it has been widely used in the weaving field.

[0003] There are mainly two production process flows for polyester drawn yarn FDY: one is the traditional process route of oiling first and then drawing, that is, oiled drawing, and its process flow is: metering pump melting and extrusion → cooling → oiling → drawing and setting → winding and forming. Although this technology has mature process, stable product quality, relatively stable physical indexes and dyeing uniformity, the energy consumption increases and oil fume is easily generated; the other is the process route of drawing first and then oiling, that is, oil-free drawing, and its process flow is metering pump melting and extrusion → cooling → drawing and setting → oiling → winding and forming. Compared with the traditional process route of oiling first and then drawing, the process technology of drawing first and then oiling is more energy-saving and environmentally friendly. However, the dyeing uniformity of this process is relatively poor. This is mainly due to factors such as the poor heat conduction efficiency of polyester, the hot roller heating method and size, etc. When the oil-free drawing process route is adopted, the filament bundle is more easily affected by the fluctuation of the spinning tension during the winding process, thus affecting the dyeing uniformity.

[0004] During the actual production process, the tension will be affected by parameters such as the temperature of the spinning pack, the temperature of the cooling air, and the intrinsic viscosity of the polyester melt. For example, when the spinning pack is regularly replaced during spinning, the spinning tension often drops after the replacement. This is mainly because the new pack needs to be preheated before being put into operation, and the preheating temperature is usually 30°C higher than the normal spinning temperature to ensure that the temperature of the newly installed pack is higher than the temperature of the spinning melt. This operation causes the spinning temperature of the melt after passing through the new pack to be higher than the normal spinning temperature, thereby causing the spinning tension to drop. As the polyester melt continuously flows through the pack, the excess heat of the pack is taken away, and the temperature of the pack gradually drops to the normal spinning temperature, but this process will last for more than 3 hours, and even reach more than 5 hours when spinning some varieties. When the spinning tension drops beyond a certain range, the grasping force of the first hot roller will drop, resulting in uneven tension distribution of the filament bundle before entering the second hot roller. This uneven tension condition will further cause the contact surface between the filament bundle and the hot roller to become uneven, thereby affecting the heating amount and the heating uniformity, and ultimately resulting in uneven degree of vitrification of the filament bundle, which in turn affects the uniformity of the drawing process and ultimately manifests as uneven dyeing effect.

[0005] To solve the above problems, the winding process flow of the existing oil-free drawing process technology is as follows: spinning pre-network bundling → two reverse U-shaped porcelain parts → roller I → roller II → roller III → roller IV → roller V → oiling → roller VI → main network → roller VII → winding and forming. The tension is increased by adjusting the positions of the two reverse U-shaped porcelain parts to restore the wire gripping force of the first hot roller (roller I). However, this method has two major problems: First, changes in component temperature, cooling air temperature, and characteristic viscosity of the polyester melt caused by replacing the spinning component lead to changes in tension that cannot be accurately detected. Often, abnormalities are only discovered after full-roll production and color judgment in the quality inspection section, and then feedback to the production section is required to know that the tension has decreased. It takes too long to discover the problem. Second, it is impossible to standardize the adjustment of the positions of the two reverse U-shaped porcelain parts. It is necessary to go through a cycle of adjustment → color judgment after dyeing → feedback that the dyeing does not meet the standard → re-adjustment → re-color judgment after dyeing until the dyeing adjustment reaches the standard, and it is impossible to achieve precise adjustment.

[0006] In the literature (Discussion on the Process of Producing Polyester FDY by Oil-Free Drawing Technology [J]. Synthetic Fiber. 2018, 47(3): 37-39), the tension is increased and the dyeing performance is improved by adjusting the entry and exit positions (i.e., angle adjustment) of the U-guide (i.e., the above two reverse U-shaped porcelain parts) to increase the contact area between the tow and roller I. However, since adjusting the angles of the two reverse U-shaped wire guiding porcelain parts requires multiple tests, it takes a long time.

[0007] Therefore, it is of great significance to study a method for improving the dyeing uniformity of oil-free drawn FDY fibers to solve the above problems. Summary of the Invention

[0008] The purpose of the present invention is to solve the problems existing in the prior art and provide a method for improving the dyeing uniformity of oil-free drawn FDY fibers.

[0009] To achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0010] A method for improving the dyeing uniformity of oil-free drawn FDY fibers. The production process flow of oil-free drawn FDY fibers is as follows: metering pump for melt extrusion → cooling → spinning pre-network bundling → the first U-shaped porcelain part → the second U-shaped porcelain part → roller I → roller II → roller III → roller IV → roller V → oiling → roller VI → main network → roller VII → winding and forming. The opening directions of the first U-shaped porcelain part and the second U-shaped porcelain part are opposite. A pressure sensor is used to detect in real time the pressure of the silk borne by the first U-shaped porcelain part. By comparing the pressure setting range with the received pressure value and according to the comparison result, the displacement of the second U-shaped porcelain part is controlled, so that the angle of the silk bundle passing through the two U-shaped porcelain parts changes, so that the pressure of the silk borne by the first U-shaped porcelain part returns to the setting range, avoiding the problem of poor dyeing caused by the change of this tension; the pressure setting range is set by the process personnel in the initial process development stage, that is, a pressure range obtained after the process conditions are mature is used as the setting range.

[0011] As a preferred technical solution:

[0012] For a method for improving the dyeing uniformity of oil-free drawn FDY fibers as described above, the second U-shaped porcelain part is located below the first U-shaped porcelain part, and roller I is located below the two U-shaped porcelain parts. The angle of the silk bundle passing through the two U-shaped porcelain parts refers to the angle between the silk bundle between the first U-shaped porcelain part and the second U-shaped porcelain part and the vertical direction; when the second U-shaped porcelain part does not move, the angle of the silk bundle passing through the two U-shaped porcelain parts is 5° to 15°; when the second U-shaped porcelain part moves, the angle change range of the silk bundle passing through the two U-shaped porcelain parts is 0° to 30° (that is, the angle changes between 0° and 30°). If it exceeds 30°, that is, the fold angle becomes larger, it will cause the silk bundle tension to increase, resulting in the situation of cold drawing of the silk bundle, and problems such as hairiness and strength reduction are likely to occur.

[0013] For a method for improving the dyeing uniformity of oil-free drawn FDY fibers as described above, the number of the first U-shaped porcelain parts and the second U-shaped porcelain parts are both multiple. The multiple first U-shaped porcelain parts and the multiple second U-shaped porcelain parts are respectively fixed on their respective U-shaped porcelain part wire guides, and the multiple first U-shaped porcelain parts and the multiple second U-shaped porcelain parts correspond one by one; one end of the U-shaped porcelain part wire guide for fixing the first U-shaped porcelain part is installed with a pressure sensor. When the silk bundle passes through the U-shaped wire guide, a certain force will be applied, and the pressure on the U-shaped wire guide can be sensed by the pressure sensor. The pressure sensor is connected to the control instrument I through a wire, the control instrument I is connected to the frequency converter I through a wire, the frequency converter I is connected to the servo motor I through a wire, and the transmission shaft I of the servo motor I is connected to a small gear, and the small gear meshes with a large gear, and the large gear is connected to the wire guide of the second U-shaped porcelain part;

[0014] The two U-shaped porcelain part wire guides are parallel to each other; the central axis of the large gear is parallel to the U-shaped porcelain part wire guide.

[0015] A method for improving the dyeing uniformity of oil-free drawn FDY fibers as described above. When the angle of the tow passing through the two U-shaped porcelain parts is 5° - 15°, the angle between the tow between the second U-shaped porcelain part and roller I and the vertical direction is also 5° - 15°.

[0016] Let the pressure setting range be the interval [a, b]. When the pressure feedback by the pressure sensor is less than a, control the movement of the second U-shaped porcelain part to increase the angle of the tow passing through the two U-shaped porcelain parts until the pressure detected by the pressure sensor reaches the pressure setting range.

[0017] When the pressure feedback by the pressure sensor is greater than b, control the movement of the second U-shaped porcelain part to decrease the angle of the tow passing through the two U-shaped porcelain parts until the detected pressure reaches the pressure setting range.

[0018] When the displacement of the second U-shaped porcelain part is controlled and the pressure on the silk borne by the first U-shaped porcelain part is within the interval [a, b] after detection, it means that the tension of the tow between roller I and roller II is also within the normal range.

[0019] A method for improving the dyeing uniformity of oil-free drawn FDY fibers as described above. A tension detection sensor is provided between roller I and roller II, and the tension detection sensor is used to detect the tension of the tow between roller I and roller II; the tension detection sensor is connected to control instrument II through a wire, control instrument II is connected to frequency converter II through a wire, frequency converter II is connected to motor II through a wire, and the transmission shaft II of motor II is connected to roller I.

[0020] Control instrument I is electrically connected to control instrument II.

[0021] When the servo motor I drives the second U-shaped porcelain part to displace so that the angle of the tow passing through the two U-shaped porcelain parts is 0°, and the pressure feedback by the pressure sensor is still greater than b, control instrument I sends a signal to control instrument II, and control instrument II controls the tension detection sensor to start. According to the monitoring value of the tension detection sensor, increase the rotation speed of roller I to make the speed difference between roller I and roller II smaller until the tension of the tow between roller I and roller II is detected to reach the tension setting range. During normal production and when the dyeing is normal, the tension measured by a handheld tensiometer for a tow is used as the tension setting range; an encoder is provided in the servo motor to monitor the rotation angle.

[0022] When adjusting the tension of the tow entering Roller I, first, through the coordinated use of a pressure sensor, Control Instrument I, frequency converter I, and servo motor I, the tension of the tow entering Roller I can be increased or decreased. However, when the tension of the tow entering Roller I is extremely large, and when the angle of the tow passing through the two U-shaped porcelain parts is adjusted to 0° by moving the second U-shaped porcelain part, and the coordinated use of the pressure sensor, Control Instrument I, frequency converter I, and servo motor I cannot adjust it to the set pressure (i.e., cannot adjust to the set tension), the tension detection sensor set between Roller I and Roller II is turned on, and the speed of Roller I is increased according to the monitoring value of the tension detection sensor until the tension of the tow between Roller I and Roller II is detected to reach the tension setting range.

[0023] Theoretically, without the pressure sensor, Control Instrument I, frequency converter I, and servo motor I, the tension of the tow at Roller I can be directly controlled to increase and decrease through the tension detection sensor, Control Instrument II, and frequency converter II. However, when the tension is too small, when using this method to increase the tension of the tow at Roller I, the speed of Roller I needs to be reduced, which will cause an increase in the speed difference between Roller I and Roller II, and instead cause an increase in the tension between Roller I and Roller II, resulting in large tow vibration and the problem of broken ends. When the tension is too large, for the normal production tow, the angle passing through the two U-shaped porcelain parts is 5° - 15°, that is, the tow still has a certain tension when passing through the second U-shaped porcelain part. By increasing the speed of Roller I and reducing the speed difference between Roller I and Roller II, the tension of the tow between Roller I and Roller II can reach the set range.

[0024] For a method of improving the dyeing uniformity of oil-free drawn FDY fibers as described above, the pre-network pressure is 0.015 ± 0.03 MPa, and the main network pressure is 0.4 ± 0.02 MPa; the oil agent concentration during oiling is 20 ± 1 wt%.

[0025] For a method of improving the dyeing uniformity of oil-free drawn FDY fibers as described above, the speed of Roller I is 1700 - 1800 m / min, the speed of Roller II is 1710 - 1810 m / min, the speed of Roller III is 1800 - 1900 m / min, the speed of Roller IV is 4100 - 4700 m / min, the speed of Roller V is 4100 - 4700 m / min, the speed of Roller VI is 4110 - 4710 m / min, the speed of Roller VII is 4115 - 4720 m / min, and the winding speed is 4100 - 4700 m / min.

[0026] For a method of improving the dyeing uniformity of oil-free drawn FDY fibers as described above, the dyeing M rate of the oil-free drawn FDY fibers is ≥ 99.5%, and the dyeing uniformity is above level 4 - 5.

[0027] Beneficial effects:

[0028] (1) The present invention can online and real-time monitor the change of the tow pressure during the production process, and can adjust the position of the second U-shaped porcelain piece in real-time and accurately according to the monitored pressure value, so that the pressure of the tow borne by the first U-shaped porcelain piece returns to the set range, avoiding the problem of poor dyeing caused by the change of the tow tension entering the roller I due to the pressure change during the production process. Even when there is a slight fluctuation in the tension, it can be optimized and adjusted in time, so as not to produce downgraded tow.

[0029] (2) A tension detection sensor is provided between roller I and roller II in the present invention. When the servo motor I drives the second U-shaped porcelain piece to displace and the angle of the tow passing through the two U-shaped porcelain pieces is 0°, if the pressure feedback by the pressure sensor is still greater than the maximum value of the pressure set range, the rotation speed of roller I is increased according to the monitoring value of the tension detection sensor, so that the speed difference between roller I and roller II becomes smaller until the detected tension reaches the tension set range. Description of the Drawings

[0030] Figure 1 is a schematic flow chart of the method for improving the dyeing uniformity of oil-free drawn FDY fibers in the present invention;

[0031] Figure 2 is a schematic structural diagram of the first U-shaped porcelain piece in the present invention;

[0032] Figure 3 is a schematic connection diagram of the first U-shaped porcelain piece and the second U-shaped porcelain piece in the present invention;

[0033] Among them, 1 - pressure sensor, 2 - control instrument I, 3 - frequency converter I, 4 - servo motor I, 5 - pinion, 6 - gear, 7 - tension sensor, 8 - control instrument II, 9 - frequency converter II, 10 - motor II, 11 - first U-shaped porcelain piece, 12 - second U-shaped porcelain piece. Detailed Embodiments

[0034] 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 not 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 also fall within the scope defined by the appended claims of this application.

[0035] To ensure the full disclosure of the performance of the substances used in each embodiment and comparative example, the manufacturers and grades of the substances are specified. Products of other manufacturers and grades that meet the limitations of the present invention are also feasible.

[0036] The test methods for the relevant performance indicators in the following embodiments and comparative examples are as follows:

[0037] Dyeing M rate: According to the standard of GB / T 6508-2015 "Test Method for Dyeing Uniformity of Polyester Filament Yarn", first, the oil-free drawn FDY fibers prepared in each example were woven into 10-cm sock tubes and then dyed respectively. Then, the dyeing uniformity grade of the sock tubes was visually evaluated by referring to the gray scale for color change. Then, according to the standard of GB / T 8960-2015 "Polyester Drawn Yarn", the sock tubes with a dyeing uniformity grade below level 4 (excluding level 4) were regarded as defective sock tubes. The dyeing M rate = (total number of sock tubes - number of defective sock tubes) / total number of sock tubes × 100%.

[0038] Dyeing uniformity: The grade was determined by referring to the gray scale for color change in GB / T 250-2008 according to the dyeing range (light and dark stripes within the same sock tube).

[0039] The sizing agent used in the examples of the present invention was obtained by uniformly mixing a commercially available sizing agent (manufactured by Tongxiang Henglong Chemical Co., Ltd., brand number TK-1001L) and water.

[0040] Example 1

[0041] A method for improving the dyeing uniformity of oil-free drawn FDY fibers, the specific steps are as follows:

[0042] The polyester melt with an intrinsic viscosity of 0.630 dL / g was metered by a metering pump, extruded through a spinneret, and then successively passed through cooling, spinning pre-network bundling, the first U-shaped porcelain part, the second U-shaped porcelain part, roller I, roller II, roller III, roller IV, roller V, sizing, roller VI, main network, roller VII, and winding forming to obtain oil-free drawn FDY fibers with a specification of 61 dtex / 24f;

[0043] Among them, the pressure setting range was 192 ± 10 cN, the tension setting range of the fiber bundle between roller I and roller II was 8 ± 1 cN, the spinning temperature was 292 °C, the cooling air temperature was 21 °C, the vertical distance from the spinneret surface to the oil nozzle was 110 cm, the pre-network pressure was 0.018 MPa, roller I, roller VI, and roller VII were not heated, roller II, roller III, roller IV, and roller V were hot rollers, the speed of roller I was 1750 m / min, the speed of roller II was 1760 m / min, the temperature of roller II was 60 °C, the speed of roller III was 1850 m / min, the temperature of roller III was 65 °C, the speed of roller IV was 4460 m / min, the temperature of roller IV was 132 °C, the speed of roller V was 4460 m / min, the temperature of roller V was 132 °C, the speed of roller VI was 4465 m / min, the speed of roller VII was 4472 m / min, the main network pressure was 0.39 MPa, the winding speed was 4460 m / min, and the sizing agent concentration during sizing was 19.5 wt%;

[0044] The opening directions of the first U-shaped porcelain part and the second U-shaped porcelain part are opposite; the second U-shaped porcelain part is located below the first U-shaped porcelain part, and roller I is located below the two U-shaped porcelain parts;

[0045] The numbers of the first U-shaped porcelain parts and the second U-shaped porcelain parts are 32 respectively. The 32 first U-shaped porcelain parts and the 32 second U-shaped porcelain parts are respectively fixed on their own U-shaped porcelain part wire guides, and the 32 first U-shaped porcelain parts and the 32 second U-shaped porcelain parts correspond one by one; the two U-shaped porcelain part wire guides are parallel to each other;

[0046] The angle at which the wire bundle passes through the two U-shaped porcelain parts is 13°;

[0047] The angle between the wire bundle between the second U-shaped porcelain part and roller I and the vertical direction is 12°;

[0048] As Figures 1 to 3 shown, one end of the U-shaped porcelain part wire guide for fixing the first U-shaped porcelain part is installed with a pressure sensor 1. The pressure sensor 1 is connected to a control instrument I 2 through a wire. The control instrument I 2 is connected to a frequency converter I 3 through a wire. The frequency converter I3 is connected to a servo motor I 4 through a wire. The transmission shaft I of the servo motor I 4 is connected to a small gear 5. The small gear 5 meshes with a large gear 6. The large gear 6 is connected to the wire guide of the second U-shaped porcelain part; the central axis of the large gear 6 is parallel to the U-shaped porcelain part wire guide;

[0049] A tension detection sensor 7 is provided between roller I and roller II. The tension detection sensor 7 is used to detect the tension of the wire bundle between roller I and roller II;

[0050] The tension detection sensor 7 is connected to a control instrument II 8 through a wire. The control instrument II 8 is connected to a frequency converter II 9 through a wire. The frequency converter II 9 is connected to a motor II 10 through a wire. The transmission shaft II of the motor II 10 is connected to roller I;

[0051] The control instrument I 2 and the control instrument II 8 are electrically connected;

[0052] When the transmission shaft I of the servo motor I 4 drives the second U-shaped porcelain part to displace and makes the angle at which the wire bundle passes through the two U-shaped porcelain parts 0°, and the pressure feedback by the pressure sensor 1 is still greater than 202 cN, the control instrument I 2 sends a signal to the control instrument II8. The control instrument II 8 controls the tension detection sensor 7 to start, and increases the rotation speed of roller I according to the monitoring value of the tension detection sensor 7, so that the speed difference between roller I and roller II becomes smaller;

[0053] When replacing the spinning pack, the preheating temperature of the spinning pack is 322 °C. At this time, the pressure value of the silk borne by the first U-shaped porcelain part 11 is detected in real time by the pressure sensor 1, which is 175 cN. Then, by comparing with the pressure setting range, it is found that the pressure feedback by the pressure sensor 1 is less than 182 cN. Subsequently, the second U-shaped porcelain part 12 is controlled to move, so that the angle of the tow passing through the two U-shaped porcelain parts is 16°, and the pressure value detected by the pressure sensor 1 is 183 cN.

[0054] After replacing the spinning pack and re-starting the production, the dyeing M rate of the oil-free drawn FDY fiber is 99.6%, and the dyeing uniformity is 4-5 levels.

[0055] Example 2

[0056] A method for improving the dyeing uniformity of oil-free drawn FDY fiber is basically the same as that in Example 1, except that: the cooling air temperature is 18 °C;

[0057] When replacing the spinning pack, the preheating temperature of the spinning pack is 322 °C. At this time, the pressure value of the silk borne by the first U-shaped porcelain part is detected in real time by the pressure sensor, which is 239 cN. Then, by comparing with the pressure setting range, it is found that the pressure feedback by the pressure sensor is greater than 202 cN. Subsequently, the second U-shaped porcelain part is controlled to move. When the angle of the tow passing through the two U-shaped porcelain parts is 0°, the pressure detected by the pressure sensor still does not reach the pressure setting range. Then, the meter I is controlled to send a signal to the control meter II, and the control meter II controls the tension detection sensor to start. According to the monitoring value of the tension detection sensor, the rotation speed of the roller I is increased to 1755 m / min, so that the tension value detected by the tension detection sensor is 8.9 cN.

[0058] After replacing the spinning pack and re-starting the production, the dyeing M rate of the oil-free drawn FDY fiber is 99.6%, and the dyeing uniformity is 4-5 levels.

[0059] Example 3

[0060] A method for improving the dyeing uniformity of oil-free drawn FDY fiber is as follows:

[0061] The polyester melt with an intrinsic viscosity of 0.610 dL / g is metered by a metering pump, extruded through a spinneret, and then successively passes through cooling, spinning pre-network bundling, the first U-shaped porcelain part, the second U-shaped porcelain part, roller I, roller II, roller III, roller IV, roller V, oiling, roller VI, main network, roller VII, and winding and forming to obtain an oil-free drawn FDY fiber with a specification of 333 dtex / 96f;

[0062] Among them, the pressure setting range is 500±25 cN, the tension setting range of the tow between roller I and roller II is 25±2 cN, the spinning temperature is 290 °C, the cooling air temperature is 21 °C, the vertical distance from the spinneret plate to the oil nozzle is 115 cm, the pre-network pressure is 0.014 MPa, the speed of roller I is 1700 m / min, the speed of roller II is 1710 m / min, the temperature of roller II is 90 °C, the speed of roller III is 1850 m / min, the temperature of roller III is 90 °C, the speed of roller IV is 4200 m / min, the temperature of roller IV is 150 °C, the speed of roller V is 4200 m / min, the temperature of roller V is 150 °C, the speed of roller VI is 4210 m / min, the speed of roller VII is 4225 m / min, the main network pressure is 0.42 MPa, the winding speed is 4200 m / min, and the oil concentration during oiling is 21.0 wt%;

[0063] The opening directions of the first U-shaped porcelain part and the second U-shaped porcelain part are opposite; the second U-shaped porcelain part is located below the first U-shaped porcelain part, and roller I is located below the two U-shaped porcelain parts;

[0064] The numbers of the first U-shaped porcelain parts and the second U-shaped porcelain parts are 20 respectively. The 20 first U-shaped porcelain parts and the 20 second U-shaped porcelain parts are respectively fixed on their respective U-shaped porcelain part wire guides, and the 20 first U-shaped porcelain parts and the 20 second U-shaped porcelain parts correspond one by one; the two U-shaped porcelain part wire guides are parallel to each other;

[0065] The angle of the tow passing through the two U-shaped porcelain parts is 5°;

[0066] The angle between the tow between the second U-shaped porcelain part and roller I and the vertical direction is 5°;

[0067] One end of the U-shaped porcelain part wire guide for fixing the first U-shaped porcelain part is equipped with a pressure sensor. The pressure sensor is connected to control instrument I through a wire. Control instrument I is connected to frequency converter I through a wire. Frequency converter I is connected to servo motor I through a wire. The transmission shaft I of servo motor I is connected to a small gear. The small gear meshes with a large gear. The large gear is connected to the wire guide of the second U-shaped porcelain part; the central axis of the large gear is parallel to the U-shaped porcelain part wire guide;

[0068] A tension detection sensor is provided between roller I and roller II. The tension detection sensor is used to detect the tension of the tow between roller I and roller II;

[0069] The tension detection sensor is connected to control instrument II through a wire. Control instrument II is connected to frequency converter II through a wire. Frequency converter II is connected to motor II through a wire. The transmission shaft II of motor II is connected to roller I;

[0070] Control instrument I and control instrument II are electrically connected;

[0071] When the transmission shaft I of the servo motor I drives the second U-shaped ceramic part to displace, and when the angle at which the tow passes through the two U-shaped ceramic parts is 0°, and the pressure feedback by the pressure sensor is still greater than 525 cN, the control instrument I sends a signal to the control instrument II, and the control instrument II controls the tension detection sensor to start, and increases the rotation speed of the roller I according to the monitoring value of the tension detection sensor, so that the speed difference between the roller I and the roller II becomes smaller;

[0072] Since the intrinsic viscosity of the polyester melt is 0.610 dL / g, the pressure value of the wire borne by the first U-shaped ceramic part detected by the pressure sensor in real time is 450 cN. Then, by comparing with the pressure setting range, it is found that the pressure feedback by the pressure sensor is less than 475 cN. Subsequently, the second U-shaped ceramic part is controlled to move, so that the angle at which the tow passes through the two U-shaped ceramic parts is 19°, and the pressure value detected by the pressure sensor is 478 cN.

[0073] The oil-free drawn FDY fiber obtained after adjusting the position of the second U-shaped ceramic part has a dyeing M rate of 99.7% and a dyeing uniformity of 4-5 levels.

[0074] Example 4

[0075] A method for improving the dyeing uniformity of oil-free drawn FDY fibers is basically the same as that in Example 3, except that: the intrinsic viscosity of the polyester melt used is 0.645 dL / g;

[0076] Since the intrinsic viscosity of the polyester melt is 0.645 dL / g, the pressure value of the wire borne by the first U-shaped ceramic part detected by the pressure sensor in real time is 583 cN. Then, by comparing with the pressure setting range, it is found that the pressure feedback by the pressure sensor is greater than 525 cN. Subsequently, the second U-shaped ceramic part is controlled to move. When the angle at which the tow passes through the two U-shaped ceramic parts is 0°, the pressure detected by the pressure sensor does not reach the pressure setting range either. Then, the control instrument I sends a signal to the control instrument II, and the control instrument II controls the tension detection sensor to start, and increases the rotation speed of the roller I to 1708 m / min according to the monitoring value of the tension detection sensor, so that the tension value detected by the tension detection sensor is 26.8 cN.

[0077] The oil-free drawn FDY fiber obtained after adjusting the position of the second U-shaped ceramic part and increasing the rotation speed of the roller I has a dyeing M rate of 99.6% and a dyeing uniformity of 4-5 levels.

[0078] Example 5

[0079] A method for improving the dyeing uniformity of oil-free drawn FDY fibers is as follows:

[0080] After the polyester melt with an intrinsic viscosity of 0.630 dL / g is metered by a metering pump, it is extruded through a spinneret, and then successively passes through cooling, pre-network bundling for spinning, the first U-shaped porcelain part, the second U-shaped porcelain part, roller I, roller II, roller III, roller IV, roller V, oiling, roller VI, main network, roller VII, and winding and forming to obtain oil-free drawn FDY fibers with a specification of 39 dtex / 48 f;

[0081] Among them, the pressure setting range is 95 ± 5 cN, the tension setting range of the tow between roller I and roller II is 6 ± 1 cN, the spinning temperature is 294 °C, the cooling air temperature is 24 °C, the vertical distance from the spinneret surface to the oil nozzle is 105 cm, the pre-network pressure is 0.015 MPa, the speed of roller I is 1780 m / min, the speed of roller II is 1790 m / min, the temperature of roller II is 50 °C, the speed of roller III is 1890 m / min, the temperature of roller III is 55 °C, the speed of roller IV is 4100 m / min, the temperature of roller IV is 125 °C, the speed of roller V is 4100 m / min, the temperature of roller V is 125 °C, the speed of roller VI is 4110 m / min, the speed of roller VII is 4115 m / min, the main network pressure is 0.38 MPa, the winding speed is 4100 m / min, and the oil agent concentration during oiling is 19.0 wt%;

[0082] The opening directions of the first U-shaped porcelain part and the second U-shaped porcelain part are opposite; the second U-shaped porcelain part is located below the first U-shaped porcelain part, and roller I is located below the two U-shaped porcelain parts;

[0083] The numbers of the first U-shaped porcelain parts and the second U-shaped porcelain parts are 32 respectively. The 32 first U-shaped porcelain parts and the 32 second U-shaped porcelain parts are respectively fixed on their own U-shaped porcelain part wire guides, and the 32 first U-shaped porcelain parts and the 32 second U-shaped porcelain parts correspond one by one; the two U-shaped porcelain part wire guides are parallel to each other;

[0084] The angle of the tow passing through the two U-shaped porcelain parts is 12°;

[0085] The angle between the tow between the second U-shaped porcelain part and roller I and the vertical direction is 11°;

[0086] One end of the U-shaped porcelain part wire guide for fixing the first U-shaped porcelain part is equipped with a pressure sensor. The pressure sensor is connected to a control instrument I through a wire. The control instrument I is connected to a frequency converter I through a wire. The frequency converter I is connected to a servo motor I through a wire. The transmission shaft I of the servo motor I is connected to a small gear. The small gear meshes with a large gear. The large gear is connected to the wire guide of the second U-shaped porcelain part; the central axis of the large gear is parallel to the U-shaped porcelain part wire guide;

[0087] A tension detection sensor is provided between roller I and roller II, and the tension detection sensor is used to detect the tension of the tow between roller I and roller II;

[0088] The tension detection sensor is connected to control instrument II through a wire, control instrument II is connected to frequency converter II through a wire, frequency converter II is connected to motor II through a wire, and the transmission shaft II of motor II is connected to roller I;

[0089] Control instrument I is electrically connected to control instrument II;

[0090] When the transmission shaft I of servo motor I drives the second U-shaped porcelain part to displace and the angle of the tow passing through the two U-shaped porcelain parts is 0°, and when the pressure fed back by the pressure sensor is still greater than 100 cN, control instrument I sends a signal to control instrument II, and control instrument II controls the tension detection sensor to start, and increases the rotation speed of roller I according to the monitoring value of the tension detection sensor, so that the speed difference between roller I and roller II becomes smaller;

[0091] Since the cooling air temperature is as high as 24°C, at this time, the pressure value of the wire received by the first U-shaped porcelain part detected by the pressure sensor in real time is 80 cN. Then, by comparing with the pressure setting range, it is found that the pressure fed back by the pressure sensor is less than 90 cN. Subsequently, the second U-shaped porcelain part is controlled to move, so that the angle of the tow passing through the two U-shaped porcelain parts is 21°, so that the pressure value detected by the pressure sensor is 90 cN.

[0092] The oil-free drawn FDY fiber obtained after adjusting the position of the second U-shaped porcelain part has a dyeing M rate of 99.5% and a dyeing uniformity of 4-5 levels.

[0093] Example 6

[0094] A method for improving the dyeing uniformity of oil-free drawn FDY fibers is basically the same as that in Example 5, except that: the cooling air temperature is 19°C;

[0095] At this time, the pressure value of the wire received by the first U-shaped porcelain part detected by the pressure sensor in real time is 130 cN. Then, by comparing with the pressure setting range, it is found that the pressure fed back by the pressure sensor is greater than 100 cN. Subsequently, the second U-shaped porcelain part is controlled to move. When the angle of the tow passing through the two U-shaped porcelain parts is 0°, the pressure detected by the pressure sensor does not reach the pressure setting range either. Then, control instrument I sends a signal to control instrument II, and control instrument II controls the tension detection sensor to start, and increases the rotation speed of roller I to 1786 m / min according to the monitoring value of the tension detection sensor, so that the tension value detected by the tension detection sensor is 6.9 cN.

[0096] The oil-free drawn FDY fiber obtained after adjusting the position of the second U-shaped porcelain part and increasing the rotation speed of roller I has a dyeing M rate of 99.6% and a dyeing uniformity of 4-5 levels.

[0097] Example 7

[0098] A method for improving the dyeing uniformity of oil-free drawn FDY fibers, the specific steps are as follows:

[0099] The polyester melt with an intrinsic viscosity of 0.628 dL / g is metered by a metering pump, extruded through a spinneret, and then successively passes through cooling, spinning pre-network bundling, the first U-shaped porcelain part, the second U-shaped porcelain part, roller I, roller II, roller III, roller IV, roller V, oiling, roller VI, main network, roller VII, and winding forming to obtain oil-free drawn FDY fibers with a specification of 105 dtex / 72f;

[0100] Among them, the pressure setting range is 265±13 cN, the tension setting range of the fiber bundle between roller I and roller II is 11±1 cN, the spinning temperature is 293°C, the cooling air temperature is 23°C, the vertical distance from the spinneret surface to the oil nozzle is 105 cm, the pre-network pressure is 0.016 MPa, the speed of roller I is 1800 m / min, the speed of roller II is 1810 m / min, the temperature of roller II is 70°C, the speed of roller III is 1900 m / min, the temperature of roller III is 73°C, the speed of roller IV is 4400 m / min, the temperature of roller IV is 138°C, the speed of roller V is 4400 m / min, the temperature of roller V is 138°C, the speed of roller VI is 4408 m / min, the speed of roller VII is 4420 m / min, the main network pressure is 0.40 MPa, the winding speed is 4400 m / min, and the oil agent concentration during oiling is 19.5 wt%.

[0101] The opening directions of the first U-shaped porcelain part and the second U-shaped porcelain part are opposite; the second U-shaped porcelain part is located below the first U-shaped porcelain part, and roller I is located below the two U-shaped porcelain parts;

[0102] The numbers of the first U-shaped porcelain part and the second U-shaped porcelain part are 24 respectively. The 24 first U-shaped porcelain parts and the 24 second U-shaped porcelain parts are respectively fixed on their respective U-shaped porcelain part wire guides, and the 24 first U-shaped porcelain parts and the 24 second U-shaped porcelain parts correspond one by one; the two U-shaped porcelain part wire guides are parallel to each other;

[0103] The angle of the fiber bundle passing through the two U-shaped porcelain parts is 10°;

[0104] The angle between the fiber bundle between the second U-shaped porcelain part and roller I and the vertical direction is 9°;

[0105] One end of the U-shaped porcelain part guide wire holder for fixing the first U-shaped porcelain part is installed with a pressure sensor. The pressure sensor is connected to the control instrument I through a wire. The control instrument I is connected to the frequency converter I through a wire. The frequency converter I is connected to the servo motor I through a wire. The transmission shaft I of the servo motor I is connected to a small gear. The small gear meshes with a large gear. The large gear is connected to the guide wire holder of the second U-shaped porcelain part. The central axis of the large gear is parallel to the guide wire holder of the U-shaped porcelain part.

[0106] A tension detection sensor is provided between roller I and roller II. The tension detection sensor is used to detect the tension of the tow between roller I and roller II.

[0107] The tension detection sensor is connected to the control instrument II through a wire. The control instrument II is connected to the frequency converter II through a wire. The frequency converter II is connected to the motor II through a wire. The transmission shaft II of the motor II is connected to roller I.

[0108] The control instrument I is electrically connected to the control instrument II.

[0109] When the transmission shaft I of the servo motor I drives the second U-shaped porcelain part to displace, and the angle of the tow passing through the two U-shaped porcelain parts is 0°, when the pressure feedback by the pressure sensor is still greater than 278 cN, the control instrument I sends a signal to the control instrument II. The control instrument II controls the tension detection sensor to start, and increases the rotation speed of roller I according to the monitoring value of the tension detection sensor, so that the speed difference between roller I and roller II becomes smaller.

[0110] Since the cooling air temperature is as high as 23°C, at this time, the pressure value of the wire borne by the first U-shaped porcelain part detected by the pressure sensor in real time is 240 cN. Then, by comparing with the pressure setting range, it is found that the pressure feedback by the pressure sensor is less than 252 cN. Subsequently, the second U-shaped porcelain part is controlled to move, so that the angle of the tow passing through the two U-shaped porcelain parts is 16°, so that the pressure value detected by the pressure sensor is 252 cN.

[0111] The oil-free drawn FDY fiber prepared after adjusting the position of the second U-shaped porcelain part has a dyeing M rate of 99.7% and a dyeing uniformity of grade 4-5.

[0112] Example 8

[0113] A method for improving the dyeing uniformity of oil-free drawn FDY fiber, the specific steps are as follows:

[0114] The polyester melt with an intrinsic viscosity of 0.628 dL / g is metered by a metering pump, extruded through a spinneret, and then successively passes through cooling, spinning pre-network bundling, the first U-shaped porcelain part, the second U-shaped porcelain part, roller I, roller II, roller III, roller IV, roller V, oiling, roller VI, main network, roller VII, and winding and forming to obtain an oil-free drawn FDY fiber with a specification of 75 dtex / 18f.

[0115] Among them, the pressure setting range is 215 ± 11 cN, the tension setting range of the tow between roller I and roller II is 8 ± 1 cN, the spinning temperature is 292 °C, the cooling air temperature is 21 °C, the vertical distance from the spinneret plate to the oil injector is 110 cm, the pre-network pressure is 0.012 MPa, the speed of roller I is 1700 m / min, the speed of roller II is 1715 m / min, the temperature of roller II is 70 °C, the speed of roller III is 1800 m / min, the temperature of roller III is 75 °C, the speed of roller IV is 4700 m / min, the temperature of roller IV is 135 °C, the speed of roller V is 4700 m / min, the temperature of roller V is 135 °C, the speed of roller VI is 4710 m / min, the speed of roller VII is 4720 m / min, the main network pressure is 0.38 MPa, the winding speed is 4700 m / min, and the concentration of the finishing oil during oiling is 19.0 wt%;

[0116] The opening directions of the first U-shaped porcelain part and the second U-shaped porcelain part are opposite; the second U-shaped porcelain part is located below the first U-shaped porcelain part, and roller I is located below the two U-shaped porcelain parts;

[0117] The numbers of the first U-shaped porcelain parts and the second U-shaped porcelain parts are 24 respectively. The 24 first U-shaped porcelain parts and the 24 second U-shaped porcelain parts are respectively fixed on their respective U-shaped porcelain part wire guides, and the 24 first U-shaped porcelain parts and the 24 second U-shaped porcelain parts correspond one by one; the two U-shaped porcelain part wire guides are parallel to each other;

[0118] The angle of the tow passing through the two U-shaped porcelain parts is 15°;

[0119] The angle between the tow between the second U-shaped porcelain part and roller I and the vertical direction is 15°;

[0120] One end of the U-shaped porcelain part wire guide for fixing the first U-shaped porcelain part is equipped with a pressure sensor. The pressure sensor is connected to control instrument I through a wire. Control instrument I is connected to frequency converter I through a wire. Frequency converter I is connected to servo motor I through a wire. The transmission shaft I of servo motor I is connected to a small gear. The small gear meshes with a large gear. The large gear is connected to the wire guide of the second U-shaped porcelain part; the central axis of the large gear is parallel to the U-shaped porcelain part wire guide;

[0121] A tension detection sensor is provided between roller I and roller II. The tension detection sensor is used to detect the tension of the tow between roller I and roller II;

[0122] The tension detection sensor is connected to control instrument II through a wire. Control instrument II is connected to frequency converter II through a wire. Frequency converter II is connected to motor II through a wire. The transmission shaft II of motor II is connected to roller I;

[0123] Control instrument I and control instrument II are electrically connected;

[0124] When the transmission shaft I of the servo motor I drives the second U-shaped ceramic part to displace, and when the angle at which the tow passes through the two U-shaped ceramic parts is 0°, if the pressure feedback by the pressure sensor is still greater than 226 cN, the control instrument I sends a signal to the control instrument II, and the control instrument II controls the tension detection sensor to start, and increases the rotation speed of the roller I according to the monitoring value of the tension detection sensor, so that the speed difference between the roller I and the roller II becomes smaller;

[0125] When replacing the spinning pack, the preheating temperature of the spinning pack is 332 °C. At this time, the pressure value of the silk borne by the first U-shaped ceramic part is detected in real time by the pressure sensor and is 156 cN. Then, by comparing with the pressure setting range, it is found that the pressure feedback by the pressure sensor is less than 204 cN. Subsequently, the second U-shaped ceramic part is controlled to move so that the angle at which the tow passes through the two U-shaped ceramic parts is 30°, so that the pressure value detected by the pressure sensor is 204 cN.

[0126] After replacing the spinning pack and re-starting the head, the dyeing M rate of the oil-free drawn FDY fiber is 99.5%, and the dyeing uniformity is 4-5 grades.

Claims

1. A method for improving the dyeing uniformity of oil-free drawn FDY fibers. The production process flow of oil-free drawn FDY fibers is as follows: metering pump for melting and extrusion → cooling → spinning pre-network bundling → the first U-shaped porcelain part → the second U-shaped porcelain part → roller I → roller II → roller III → roller IV → roller V → oiling → roller VI → main network → roller VII → winding and forming. The opening directions of the first U-shaped porcelain part and the second U-shaped porcelain part are opposite. It is characterized in that: The pressure exerted by the wire on the first U-shaped ceramic part is detected in real time by a pressure sensor. By comparing the pressure setting range with the received pressure value and based on the comparison result, the displacement of the second U-shaped ceramic part is controlled, causing the angle of the wire bundle passing through the two U-shaped ceramic parts to change, so that the pressure exerted by the wire on the first U-shaped ceramic part returns to the set range.

2. The method for improving the dyeing uniformity of oil-free drawn FDY fibers according to claim 1, wherein The angle of the wire bundle passing through the two U-shaped ceramic parts refers to the angle between the wire bundle between the first U-shaped ceramic part and the second U-shaped ceramic part and the vertical direction; when the second U-shaped ceramic part does not move, the angle of the wire bundle passing through the two U-shaped ceramic parts is 5° - 15°. When the second U-shaped ceramic part moves, the angle change range of the wire bundle passing through the two U-shaped ceramic parts is 0° - 30°.

3. A method for improving the dyeing uniformity of oil-free drawn FDY fibers according to claim 2, characterized in that, The number of the first U-shaped ceramic parts and the second U-shaped ceramic parts is multiple. Multiple first U-shaped ceramic parts and multiple second U-shaped ceramic parts are respectively fixed on their respective U-shaped ceramic part wire guides, and multiple first U-shaped ceramic parts and multiple second U-shaped ceramic parts correspond one by one; one end of the U-shaped ceramic part wire guide for fixing the first U-shaped ceramic part is equipped with a pressure sensor, the pressure sensor is connected to a control instrument I through a wire, the control instrument I is connected to a frequency converter I through a wire, the frequency converter I is connected to a servo motor I through a wire, and the transmission shaft I of the servo motor I is connected to a small gear, the small gear meshes with a large gear, and the large gear is connected to the wire guide of the second U-shaped ceramic part; The two U-shaped ceramic part wire guides are parallel to each other; the central axis of the large gear is parallel to the U-shaped ceramic part wire guide.

4. A method for improving the dyeing uniformity of oil-free drawn FDY fibers according to claim 3, characterized in that When the angle of the wire bundle passing through the two U-shaped ceramic parts is 5° - 15°, the angle between the wire bundle between the second U-shaped ceramic part and the roller I and the vertical direction is also 5° - 15°. Denote the pressure setting range as the interval [a, b]. When the pressure feedback by the pressure sensor is less than pressure a, control the second U-shaped ceramic part to move, making the angle of the wire bundle passing through the two U-shaped ceramic parts larger until the pressure detected by the pressure sensor reaches the pressure setting range; When the pressure feedback by the pressure sensor is greater than b, control the second U-shaped ceramic part to move, making the angle of the wire bundle passing through the two U-shaped ceramic parts smaller until the detected pressure reaches the pressure setting range.

5. A method for improving the dyeing uniformity of oil-free drawn FDY fibers according to claim 4, characterized in that, A tension detection sensor is provided between the roller I and the roller II. The tension detection sensor is used to detect the tension of the wire bundle between the roller I and the roller II; the tension detection sensor is connected to a control instrument II through a wire, the control instrument II is connected to a frequency converter II through a wire, the frequency converter II is connected to a motor II through a wire, and the transmission shaft II of the motor II is connected to the roller I; The control instrument I and the control instrument II are electrically connected; When the transmission shaft I of the servo motor I drives the second U-shaped ceramic part to displace and the angle of the wire bundle passing through the two U-shaped ceramic parts is 0°, and when the pressure feedback by the pressure sensor is still greater than b, the control instrument I sends a signal to the control instrument II, and the control instrument II controls the tension detection sensor to start, and increases the rotation speed of the roller I according to the monitoring value of the tension detection sensor, making the speed difference between the roller I and the roller II smaller until the tension of the wire bundle between the roller I and the roller II detected reaches the tension setting range.

6. A method for improving the dyeing uniformity of oil-free drawn FDY fibers according to claim 1, characterized in that, The pre-network pressure is 0.015 ± 0.03 MPa, and the main network pressure is 0.4 ± 0.02 MPa; the oil agent concentration during oiling is 20 ± 1 wt%.

7. A method for improving the dyeing uniformity of oil-free drawn FDY fibers according to claim 1, characterized in that, The speed of roller I is 1700 - 1800 m / min, the speed of roller II is 1710 - 1810 m / min, the speed of roller III is 1800 - 1900 m / min, the speed of roller IV is 4100 - 4700 m / min, the speed of roller V is 4100 - 4700 m / min, the speed of roller VI is 4110 - 4710 m / min, the speed of roller VII is 4115 - 4720 m / min, and the winding speed is 4100 - 4700 m / min.

8. A method for improving the dyeing uniformity of oil-free drawn FDY fibers according to claim 1, characterized in that The dyeing M rate of the oil-free drawn FDY fiber is ≥ 99.5%, and the dyeing uniformity is above grade 4 - 5.

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