Method for improving dyeing uniformity of oil-free drawn fdy fiber

Abstract

The application belongs to the technical field of polyester filaments, and discloses a method for improving dyeing uniformity of oil-free drafting FDY fibers, which utilizes a pressure sensor to detect the pressure of the yarn borne by the first U-shaped porcelain piece in real time, compares the set pressure range with the received pressure value, controls displacement of the second U-shaped porcelain piece according to the comparison result, changes the angle of the yarn bundle passing through the two U-shaped porcelain pieces, and makes the pressure of the yarn borne by the first U-shaped porcelain piece return to the set range. The application can monitor the change of the yarn bundle tension in the production process in real time, and adjust the tension change of the yarn bundle in real time and accurately according to the detected pressure value, thereby avoiding the dyeing problem caused by the tension change in the production process.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of polyester filaments, and relates to a method for improving dyeing uniformity of oil-free drawing FDY fibers. BACKGROUND

[0002] The polyester drawing yarn (FDY) is a fully drawn yarn produced by one-step spinning and setting, and is widely used in the weaving field because it can be directly used for weaving due to high breaking strength and suitable breaking elongation.

[0003] There are two main production process flows of the polyester drawing yarn (FDY): one is the traditional pre-oiling and post-drawing process route, that is, oil drawing, and the process flow is metering pump melting extrusion, cooling, oiling, drawing and setting, and winding and forming. Although the technology is mature, the product quality is stable, and the physical indexes and dyeing uniformity are relatively stable, the energy consumption is increased and oil fume is easily generated. The other is the pre-drawing and post-oiling process route, that is, oil-free drawing, and the process flow is metering pump melting extrusion, cooling, drawing and setting, oiling, and winding and forming. Compared with the traditional pre-oiling and post-drawing process route, the pre-drawing and post-oiling process technology is more energy-saving and environmentally friendly, but the dyeing uniformity is relatively poor. This is mainly due to the poor heat conduction efficiency of polyester, the heating mode and size of the hot roller and other factors, so that the yarn is more easily affected by the spinning tension fluctuation in the winding process when the oil-free drawing process route is adopted, thereby affecting the dyeing uniformity.

[0004] In the actual production process, the tension is affected by parameters such as the spinning assembly temperature, the cooling air temperature, and the intrinsic viscosity of the polyester melt. For example, the spinning assembly is replaced regularly, but the spinning tension often decreases after the assembly is replaced. This is mainly because the new assembly needs to be preheated before being put into operation, and the preheating temperature is usually 30 DEG C higher than the normal spinning temperature, so as to ensure that the temperature of the newly put into operation assembly is higher than the temperature of the spinning melt. This operation causes the out-silk temperature of the melt after passing through the new assembly to be higher than the normal spinning temperature, thereby causing the spinning tension to decrease. With the polyester melt continuously flowing through the assembly, the excess heat of the assembly is taken away, and the temperature of the assembly gradually decreases to the normal spinning temperature, but this process will last for more than 3 hours, or even more than 5 hours when the spinning part is changed. When the spinning tension decreases beyond a certain range, the first hot roller will have a decreased yarn catching force, resulting in uneven tension distribution of the yarn before entering the second hot roller. This uneven tension condition will further cause the contact surface between the yarn and the hot roller to become uneven, thereby affecting the heating amount and the uniformity of heating, and finally causing the glass transition degree of the yarn to be uneven, thereby affecting the uniformity of the drawing process, and finally affecting the dyeing effect.

[0005] To solve the above problems, the existing oil-free drafting process technology winding process is: spinning pre-network cluster → two reverse U-shaped porcelain parts → roller I → roller II → roller III → roller IV → roller V → oiling → roller VI → main network → roller VII → winding forming, which is to increase the tension by adjusting the position of the two reverse U-shaped porcelain parts to restore the first heat roller (roller I) to increase the tension. However, this method has two problems: first, the change of the component temperature caused by the replacement of the spinning assembly, the change of the cooling air temperature, the change of the intrinsic viscosity of the polyester melt, etc. which leads to the change of the tension cannot be accurately detected, often need to be detected after the production of full roll of yarn through the quality inspection section, and then feedback to the production section to know the tension drop, the problem discovery takes too long; second, the position adjustment of the two reverse U-shaped porcelain parts cannot be standardized, and needs to go through the cycle of adjustment → dyeing and color judgment → feedback of non-standard dyeing → re-adjustment → re-dyeing and color judgment until the dyeing reaches the standard, and cannot be accurately adjusted.

[0006] The document (Process discussion on polyester FDY produced by oil-free drafting technology [J]. Synthetic fiber. 2018, 47(3): 37-39) is to increase the contact area of the yarn and the roller I by adjusting the in-out position (i.e. angle adjustment) of the U-guide (i.e. the above two reverse U-shaped porcelain parts), thereby increasing the tension and improving the dyeing performance, but the adjustment of the angle of the two reverse U-shaped guide porcelain parts needs to go through many tests and takes a long time.

[0007] Therefore, it is of great significance to study a method for improving the dyeing uniformity of oil-free drafting FDY fiber to solve the above problems. SUMMARY

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

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

[0010] The application discloses a method for improving dyeing uniformity of oil-free drawing FDY fibers, and the production process of the oil-free drawing FDY fibers comprises the following steps: metering pump melting extrusion, cooling, spinning pre-networking bunching, a first U-shaped porcelain piece, a second U-shaped porcelain piece, roller I, roller II, roller III, roller IV, roller V, oiling, roller VI, main networking, roller VII and winding forming, the opening directions of the first U-shaped porcelain piece and the second U-shaped porcelain piece are opposite, the pressure sensor is used to detect the pressure of the yarn borne by the first U-shaped porcelain piece in real time, the pressure setting range is compared with the received pressure value, and the second U-shaped porcelain piece is controlled to displace according to the comparison result, so that the angle of the yarn through the two U-shaped porcelain pieces is changed, the pressure of the yarn borne by the first U-shaped porcelain piece is returned to the setting range, and the dyeing problem caused by the change of the tension is avoided; the pressure setting range is set by a process personnel in an initial process development stage, that is, a pressure range obtained after the process condition is mature is taken as the setting range.

[0011] As a preferred technical scheme,

[0012] The method for improving dyeing uniformity of oil-free drawing FDY fibers, the second U-shaped porcelain piece is located below the first U-shaped porcelain piece, the roller I is located below the two U-shaped porcelain pieces, the angle of the yarn through the two U-shaped porcelain pieces refers to the angle of the yarn between the first U-shaped porcelain piece and the second U-shaped porcelain piece and the vertical direction, the angle of the yarn through the two U-shaped porcelain pieces is 5-15 degrees when the second U-shaped porcelain piece does not displace, and the angle of the yarn through the two U-shaped porcelain pieces changes in the range of 0-30 degrees (that is, the angle changes between 0-30 degrees) when the second U-shaped porcelain piece displaces; if the angle exceeds 30 degrees, that is, the folding angle is large, the yarn tension is large, the yarn is subjected to cold stretching, and the problems of hairiness and strength reduction are prone to occur.

[0013] The method for improving dyeing uniformity of oil-free drawing FDY fibers, the number of the first U-shaped porcelain pieces and the second U-shaped porcelain pieces is multiple respectively, the multiple first U-shaped porcelain pieces and the multiple second U-shaped porcelain pieces are fixed on the respective U-shaped porcelain piece yarn guides respectively, and the multiple first U-shaped porcelain pieces and the multiple second U-shaped porcelain pieces correspond to each other one by one; the U-shaped porcelain piece yarn guide for fixing the first U-shaped porcelain piece is provided with a pressure sensor at one end, when the yarn passes through the U-shaped yarn guide, a certain force is applied, the pressure of the U-shaped yarn guide can be sensed through the pressure sensor, the pressure sensor is connected with a control instrument I through a wire, the control instrument I is connected with a frequency converter I through a wire, the frequency converter I is connected with a servo motor I through a wire, a transmission shaft I of the servo motor I is connected with a pinion, the pinion is engaged with a gear wheel, and the gear wheel is connected with the yarn guide of the second U-shaped porcelain piece.

[0014] The two U-shaped porcelain piece yarn guides are parallel to each other, and the central axis of the gear wheel is parallel to the U-shaped porcelain piece yarn guide.

[0015] The method for improving the dyeing uniformity of the oil-free drawing FDY fiber, when the angle of the yarn passing through the two U-shaped porcelain pieces is 5°-15°, the angle of the yarn between the second U-shaped porcelain piece and the roller I is also 5°-15°;

[0016] The pressure setting range is interval [a, b], when the pressure feedback by the pressure sensor is less than a, the second U-shaped porcelain piece is controlled to move, the angle of the yarn passing through the two U-shaped porcelain pieces is increased 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, the second U-shaped porcelain piece is controlled to move, the angle of the yarn passing through the two U-shaped porcelain pieces is decreased until the detected pressure reaches the pressure setting range.

[0018] When the second U-shaped porcelain piece is controlled to displace, and the pressure of the yarn borne by the first U-shaped porcelain piece is detected in interval [a, b], it represents that the tension of the yarn between the roller I and the roller II is also in the normal range.

[0019] The method for improving the dyeing uniformity of the oil-free drawing FDY fiber, the tension detection sensor is arranged between the roller I and the roller II, the tension detection sensor is used for detecting the tension of the yarn between the roller I and the roller II; the tension detection sensor is connected with the control instrument II through a wire, the control instrument II is connected with the frequency converter II through a wire, the frequency converter II is connected with the motor II through a wire, and the transmission shaft II of the motor II is connected with the roller I;

[0020] The control instrument I and the control instrument II are electrically connected;

[0021] When the servo motor I drives the second U-shaped porcelain piece to displace, the angle of the yarn passing through the two U-shaped porcelain pieces is 0°, and the pressure feedback by the pressure sensor is still greater than b, the control instrument I sends a signal to the control instrument II, the control instrument II controls the tension detection sensor to start, the speed of the roller I is increased according to the monitoring value of the tension detection sensor, the speed difference between the roller I and the roller II is decreased until the tension of the yarn between the roller I and the roller II reaches the tension setting range, in the normal production and the normal dyeing, the tension of one yarn measured by the handheld tension meter is used as the tension setting range; the encoder is arranged in the servo motor, and the rotation angle can be monitored;

[0022] When the tension of the yarn entering the roller I needs to be adjusted, the tension of the yarn entering the roller I is first increased or decreased by the cooperation of the pressure sensor, the control instrument I, the frequency converter I and the servo motor I; but when the tension of the yarn entering the roller I is very large, the angle of the yarn passing through the two U-shaped porcelain pieces is adjusted to 0° by moving the second U-shaped porcelain piece, and the cooperation of the pressure sensor, the control instrument I, the frequency converter I and the servo motor I cannot adjust the tension to the set pressure (i.e. cannot adjust the tension to the set tension), the tension detection sensor arranged between the roller I and the roller II is turned on, and the speed of the roller I is increased according to the monitoring value of the tension detection sensor until the tension of the yarn between the roller I and the roller II reaches the tension setting range;

[0023] In theory, without the pressure sensor, the control instrument I, the frequency converter I and the servo motor I, the tension of the yarn in the roller I can be directly controlled to increase and decrease by the tension detection sensor, the control instrument II and the frequency converter II. However, when the tension is too small, the speed of the roller I needs to be reduced to increase the tension of the yarn in the roller I by this method, which will increase the speed difference between the roller I and the roller II, and in turn increase the tension between the roller I and the roller II, causing the yarn to vibrate and break. When the tension is too large, the angle of the yarn passing through the two U-shaped porcelain pieces is 5°-15° during normal production of the yarn, i.e. the yarn still has a certain tension when passing through the second U-shaped porcelain piece, and the speed of the roller I is increased to reduce the speed difference between the roller I and the roller II, so that the tension of the yarn between the roller I and the roller II reaches the set range.

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

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

[0026] The method for improving the dyeing uniformity of the oil-free drawn FDY fiber as described above, the dyeing M rate of the oil-free drawn FDY fiber is ≥99.5%, and the dyeing uniformity is ≥4-5 levels.

[0027] Beneficial effects:

[0028] (1) The present application can monitor the change of the filament pressure in the production process in real time, 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 filament 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 tension of the filament entering the roller I due to the change of the pressure in the production process. Even if the tension appears a slight fluctuation, it can also be timely optimized and adjusted, so as to avoid the production of downgraded filament.

[0029] (2) The present application is provided with a tension detection sensor between the roller I and the roller II. When the servo motor I drives the second U-shaped porcelain piece to displace, the angle of the filament passing through the two U-shaped porcelain pieces is 0°, and the pressure feedback by the pressure sensor is still greater than the maximum value of the pressure set range, the speed of the roller I is increased 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, until the detected tension reaches the tension set range. BRIEF DESCRIPTION OF DRAWINGS

[0030] Fig. 1 The flowchart of the method for improving the dyeing uniformity of oil-free drawing FDY fiber of the present application;

[0031] Fig. 2 The structure diagram of the first U-shaped porcelain piece of the present application;

[0032] Fig. 3 The connection diagram of the first U-shaped porcelain piece and the second U-shaped porcelain piece of the present application;

[0033] Among them, 1 is a pressure sensor, 2 is a control instrument I, 3 is a frequency converter I, 4 is a servo motor I, 5 is a small gear, 6 is a large gear, 7 is a tension sensor, 8 is a control instrument II, 9 is a frequency converter II, 10 is a motor II, 11 is a first U-shaped porcelain piece, and 12 is a second U-shaped porcelain piece. DETAILED DESCRIPTION

[0034] The present application will be further described in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present application and not to limit the scope of the present application. In addition, it should be understood that after reading the content taught by the present application, those skilled in the art can make various modifications or modifications to the present application, and these equivalent forms also fall within the scope defined by the claims attached to the present application.

[0035] In order to fully disclose the properties of the substances used in each embodiment and comparative example, the manufacturer and brand of the substance are written, and the products of other manufacturers and brands that meet the definition of the present application are also feasible.

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

[0037] Dyeing M rate: according to GB / T 6508-2015 "Polyester filament dyeing uniformity test method" standard, first, the oil-free drawing FDY fiber prepared in each example is woven into a 10cm sock tube and then dyed, and then the dyeing uniformity grade of the sock tube is evaluated by comparing the color change with the gray sample card. Then according to GB / T 8960-2015 "Polyester drawing yarn" standard, the sock tube with a dyeing uniformity grade of 4 levels or less (not including 4 levels) is a poor sock tube, and the dyeing M rate = (the total number of sock tubes-the number of poor sock tubes) / the total number of sock tubes x 100%.

[0038] Dyeing uniformity: according to the dyeing range (light and dark stripes in the same section of the sock tube), the grade is determined by referring to the evaluation of the color change with the gray sample card in GB / T 250-2008 standard.

[0039] The oiling agent used in the embodiment of the present application is obtained by uniformly mixing a commercially available oil agent (manufacturer: Tongxiang Henglong Chemical Co., Ltd., brand: TK-1001L) and water.

[0040] Example 1

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

[0042] The polyester melt with an intrinsic viscosity of 0.630 dL / g is metered by a metering pump, then extruded through a spinneret, and then sequentially passes through cooling, spinning pre-networking bundling, the first U-shaped porcelain piece, the second U-shaped porcelain piece, roller I, roller II, roller III, roller IV, roller V, oiling, roller VI, main networking, roller VII, and is formed into 61dtex / 24f oil-free drawing FDY fiber after winding;

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

[0044] The opening direction of the first U-shaped porcelain piece and the second U-shaped porcelain piece is opposite; the second U-shaped porcelain piece is located below the first U-shaped porcelain piece, and the roller I is located below the two U-shaped porcelain pieces;

[0045] The number of the first U-shaped porcelain pieces and the second U-shaped porcelain pieces is 32 respectively, 32 first U-shaped porcelain pieces and 32 second U-shaped porcelain pieces are fixed on the respective U-shaped porcelain piece wire guide frame respectively, and the 32 first U-shaped porcelain pieces and the 32 second U-shaped porcelain pieces correspond to each other one by one; the two U-shaped porcelain piece wire guide frames are parallel to each other;

[0046] The angle of the filament passing through the two U-shaped porcelain pieces is 13°;

[0047] The angle of the filament between the second U-shaped porcelain piece and the roller I and the vertical direction is 12°;

[0048] As shown in Figs. 1-3 The U-shaped porcelain piece wire guide frame for fixing the first U-shaped porcelain piece is provided with a pressure sensor 1 at one end, 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 I 3 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 pinion 5, the pinion 5 is engaged with a large gear 6, and the large gear 6 is connected with the wire guide frame of the second U-shaped porcelain piece; the central axis of the large gear 6 is parallel to the U-shaped porcelain piece wire guide frame;

[0049] A tension detection sensor 7 is arranged between the roller I and the roller II, and the tension detection sensor 7 is used for detecting the tension of the filament between the roller I and the 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, and the transmission shaft II of the motor II 10 is connected to the 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 piece to displace, the angle of the filament passing through the two U-shaped porcelain pieces is 0°, and the pressure feedback by the pressure sensor 1 is still greater than 202cN, the control instrument I 2 sends a signal to the control instrument II 8, the control instrument II 8 controls the tension detection sensor 7 to start, and the speed of the roller I is increased according to the monitoring value of the tension detection sensor 7, so that the speed difference between the roller I and the roller II becomes smaller;

[0053] When the spinning assembly is replaced, the preheating temperature of the spinning assembly is 322℃, at this time the pressure value of the first U-shaped porcelain piece 11 bearing the yarn is detected by the pressure sensor 1 in real time, and then it is found through comparison with the pressure setting range that the pressure feedback by the pressure sensor 1 is less than 182cN, then the second U-shaped porcelain piece 12 is controlled to move, the angle of the yarn passing through the two U-shaped porcelain pieces is 16°, so that the pressure value detected by the pressure sensor 1 is 183cN.

[0054] After replacing the spinning assembly, the dyeing M rate of the oil-free drawing FDY fiber prepared after re-starting 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 drawing FDY fiber, which is basically the same as example 1, except that the cooling air temperature is 18℃;

[0057] When the spinning assembly is replaced, the preheating temperature of the spinning assembly is 322℃, at this time the pressure value of the first U-shaped porcelain piece 11 bearing the yarn is detected by the pressure sensor 1 in real time, and then it is found through comparison with the pressure setting range that the pressure feedback by the pressure sensor 1 is less than 182cN, then the second U-shaped porcelain piece 12 is controlled to move, the angle of the yarn passing through the two U-shaped porcelain pieces is 16°, so that the pressure value detected by the pressure sensor 1 is 183cN.

[0058] After replacing the spinning assembly, the dyeing M rate of the oil-free drawing FDY fiber prepared after re-starting 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 drawing FDY fiber, the specific steps are as follows:

[0061] The polyester melt with an intrinsic viscosity of 0.610dL / g is metered by a metering pump, then extruded through a spinneret, and then sequentially passes through cooling, spinning pre-networking and bundling, the first U-shaped porcelain piece, the second U-shaped porcelain piece, roll I, roll II, roll III, roll IV, roll V, oiling, roll VI, main networking, roll VII, and winding to form an oil-free drawing FDY fiber with a specification of 333dtex / 96f.

[0062] The parameters are as follows: pressure setting range: 500±25cN; tension setting range of filament bundle between roller I and roller II: 25±2cN; spinning temperature: 290℃; cooling air temperature: 21℃; vertical distance from spinneret to oil nozzle: 115cm; pre-network pressure: 0.014MPa; roller I speed: 1700m / min; roller II speed: 1710m / min; roller II temperature: 90℃; roller III speed: 1850m / min; roller III temperature: 90℃; roller IV speed: 4200m / min; roller IV temperature: 150℃; roller V speed: 4200m / min; roller V temperature: 150℃; roller VI speed: 4210m / min; roller VII speed: 4225m / min; main network pressure: 0.42MPa; winding speed: 4200m / min; oil concentration during oiling: 21.0wt%.

[0063] The opening directions of the first U-shaped ceramic piece and the second U-shaped ceramic piece are opposite; the second U-shaped ceramic piece is located below the first U-shaped ceramic piece, and roller I is located below both U-shaped ceramic pieces;

[0064] The number of the first U-shaped ceramic component and the second U-shaped ceramic component are 20 each. The 20 first U-shaped ceramic components and the 20 second U-shaped ceramic components are fixed on their respective U-shaped ceramic component guide frames, and the 20 first U-shaped ceramic components and the 20 second U-shaped ceramic components correspond one-to-one; the two U-shaped ceramic component guide frames are parallel to each other.

[0065] The angle at which the filament passes through the two U-shaped ceramic pieces is 5°.

[0066] The angle between the filament bundle between the second U-shaped ceramic piece and roller I and the vertical direction is 5°.

[0067] A pressure sensor is installed at one end of the U-shaped ceramic guide frame used to fix the first U-shaped ceramic component. The pressure sensor is connected to the control instrument I via a wire. The control instrument I is connected to the frequency converter I via a wire. The frequency converter I is connected to the servo motor I via a wire. The drive shaft I of the servo motor I is connected to a pinion gear. The pinion gear meshes with a large gear. The large gear is connected to the guide frame of the second U-shaped ceramic component. The central axis of the large gear is parallel to the U-shaped ceramic guide frame.

[0068] A tension detection sensor is installed between roller I and roller II. The tension detection sensor is used to detect the tension of the filament bundle between roller I and roller II.

[0069] The tension detection sensor is connected to control instrument II via a wire. Control instrument II is connected to frequency converter II via a wire. Frequency converter II is connected to motor II via a wire. The drive 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 porcelain piece to displace, the angle of the yarn passing through the two U-shaped porcelain pieces 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, the control instrument II controls the tension detection sensor to start, and the speed of the roller I is increased 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 yarn borne by the first U-shaped porcelain piece is detected by the pressure sensor in real time, and then it is found by comparison with the pressure setting range that the pressure feedback by the pressure sensor is less than 475 cN. Then the second U-shaped porcelain piece is controlled to move, so that the angle of the yarn passing through the two U-shaped porcelain pieces is 19°, and the pressure value detected by the pressure sensor is 478 cN.

[0073] The dyeing M rate of the oil-free drawing FDY fiber prepared after adjusting the position of the second U-shaped porcelain piece is 99.7%, and the dyeing uniformity is 4-5 levels.

[0074] Example 4

[0075] A method for improving the dyeing uniformity of oil-free drawing FDY fiber, which is basically the same as 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 yarn borne by the first U-shaped porcelain piece is detected by the pressure sensor in real time, and then it is found by comparison with the pressure setting range that the pressure feedback by the pressure sensor is greater than 525 cN. Then the second U-shaped porcelain piece is controlled to move, and when the angle of the yarn passing through the two U-shaped porcelain pieces is 0°, the pressure detected by the pressure sensor also does not reach the pressure setting range. The control instrument I sends a signal to the control instrument II, the control instrument II controls the tension detection sensor to start, and the speed of the roller I is increased 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 dyeing M rate of the oil-free drawing FDY fiber prepared after adjusting the position of the second U-shaped porcelain piece and increasing the speed of the roller I is 99.6%, and the dyeing uniformity is 4-5 levels.

[0078] Example 5

[0079] A method for improving the dyeing uniformity of oil-free drawing FDY fiber, the specific steps are as follows:

[0080] The polyester melt with an intrinsic viscosity of 0.630 dL / g is metered by a metering pump, extruded through a spinneret, and then sequentially passes through cooling, spinning pre-network bundling, a first U-shaped porcelain piece, a second U-shaped porcelain piece, roller I, roller II, roller III, roller IV, roller V, oiling, roller VI, main network, roller VII, and is wound to form an oil-free drawn FDY fiber with a specification of 39 dtex / 48 f;

[0081] The pressure setting range is 95±5 cN, the tension of the yarn between roller I and roller II is set to 6±1 cN, the spinning temperature is 294℃, the cooling air temperature is 24℃, 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℃, the speed of roller III is 1890 m / min, the temperature of roller III is 55℃, the speed of roller IV is 4100 m / min, the temperature of roller IV is 125℃, the speed of roller V is 4100 m / min, the temperature of roller V is 125℃, 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, and 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 piece and the second U-shaped porcelain piece are opposite, the second U-shaped porcelain piece is located below the first U-shaped porcelain piece, and roller I is located below the two U-shaped porcelain pieces;

[0083] The number of the first U-shaped porcelain pieces and the second U-shaped porcelain pieces is 32 respectively, the 32 first U-shaped porcelain pieces and the 32 second U-shaped porcelain pieces are fixed on the respective U-shaped porcelain piece guide frames, and the 32 first U-shaped porcelain pieces and the 32 second U-shaped porcelain pieces correspond one by one; the two U-shaped porcelain piece guide frames are parallel to each other;

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

[0085] The angle of the yarn between the second U-shaped porcelain piece and roller I with the vertical direction is 11°;

[0086] One end of the U-shaped porcelain piece guide frame for fixing the first U-shaped porcelain piece is installed with a pressure sensor, the pressure sensor is connected to control instrument I through wires, control instrument I is connected to frequency converter I through wires, frequency converter I is connected to servo motor I through wires, the transmission shaft I of servo motor I is connected to a pinion, the pinion is engaged with a gear, and the gear is connected with the guide frame of the second U-shaped porcelain piece; the central axis of the gear is parallel to the U-shaped porcelain piece guide frame;

[0087] A tension detection sensor is arranged between the roller I and the roller II, and the tension detection sensor is used for detecting the tension of the fiber bundle between the roller I and the roller II;

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

[0089] The control instrument I is electrically connected with the control instrument II;

[0090] When the transmission shaft I of the servo motor I drives the second U-shaped porcelain piece to displace, the angle of the fiber bundle passing through the two U-shaped porcelain pieces is 0°, and the pressure feedback by the pressure sensor is still greater than 100 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 the speed of the roller I is increased 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.

[0091] Since the cooling air temperature is as high as 24 ℃, the pressure value of the fiber borne by the first U-shaped porcelain piece is detected by the pressure sensor in real time as 80 cN, then it is found through comparison with the pressure setting range that the pressure feedback by the pressure sensor is less than 90 cN, then the second U-shaped porcelain piece is controlled to move, the angle of the fiber bundle passing through the two U-shaped porcelain pieces is 21°, and the pressure value detected by the pressure sensor is 90 cN.

[0092] The dyeing M rate of the oil-free drawing FDY fiber prepared after adjusting the position of the second U-shaped porcelain piece is 99.5%, and the dyeing uniformity is 4-5 levels.

[0093] Embodiment 6

[0094] A method for improving the dyeing uniformity of an oil-free drawing FDY fiber, which is basically the same as that in Embodiment 5, except that the cooling air temperature is 19 ℃.

[0095] At this time, the pressure value of the fiber borne by the first U-shaped porcelain piece is detected by the pressure sensor in real time as 130 cN, then it is found through comparison with the pressure setting range that the pressure feedback by the pressure sensor is greater than 100 cN, then the second U-shaped porcelain piece is controlled to move, when the angle of the fiber bundle passing through the two U-shaped porcelain pieces is 0°, the pressure detected by the pressure sensor also does not reach the pressure setting range, the control instrument I sends a signal to the control instrument II, the control instrument II controls the tension detection sensor to start, and the speed of the roller I is increased 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 dyeing M rate of the oil-free drawing FDY fiber prepared after adjusting the position of the second U-shaped porcelain piece and increasing the speed of the roller I is 99.6%, and the dyeing uniformity is 4-5 levels.

[0097] Embodiment 7

[0098] A method for improving the dyeing uniformity of oil-free drawing FDY fiber, 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, then extruded through a spinneret, and then sequentially passes through cooling, spinning pre-network bundling, the first U-shaped porcelain piece, the second U-shaped porcelain piece, roller I, roller II, roller III, roller IV, roller V, oiling, roller VI, main network, roller VII, and is wound to form a 105 dtex / 72 f oil-free drawing FDY fiber;

[0100] The pressure setting range is 265±13 cN, the tension of the yarn between roller I and roller II is set to 11±1 cN, the spinning temperature is 293℃, the cooling air temperature is 23℃, 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℃, the speed of roller III is 1900 m / min, the temperature of roller III is 73℃, the speed of roller IV is 4400 m / min, the temperature of roller IV is 138℃, the speed of roller V is 4400 m / min, the temperature of roller V is 138℃, 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, and the winding speed is 4400 m / min. The oil concentration is 19.5wt% when oiling.

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

[0102] The number of the first U-shaped porcelain pieces and the second U-shaped porcelain pieces is 24 respectively, the 24 first U-shaped porcelain pieces and the 24 second U-shaped porcelain pieces are fixed on the respective U-shaped porcelain piece guide frames, and the 24 first U-shaped porcelain pieces and the 24 second U-shaped porcelain pieces correspond one by one; the two U-shaped porcelain piece guide frames are parallel to each other;

[0103] The angle of the yarn passing through the two U-shaped porcelain pieces is 10°;

[0104] The angle of the yarn between the second U-shaped porcelain piece and roller I with the vertical direction is 9°;

[0105] The U-shaped porcelain piece guide wire frame at one end of the U-shaped porcelain piece for fixing the first U-shaped porcelain piece is provided with a pressure sensor, the pressure sensor is connected with a control instrument I through a wire, the control instrument I is connected with a frequency converter I through a wire, the frequency converter I is connected with a servo motor I through a wire, a transmission shaft I of the servo motor I is connected with a pinion, the pinion is engaged with a gear, and the gear is connected with the guide wire frame of the second U-shaped porcelain piece; and the central axis of the gear is parallel to the U-shaped porcelain piece guide wire frame;

[0106] A tension detection sensor is arranged between the roller I and the roller II, and is used for detecting the tension of the filament between the roller I and the roller II;

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

[0108] The control instrument I and the control instrument II are electrically connected;

[0109] When the transmission shaft I of the servo motor I drives the second U-shaped porcelain piece to displace, the angle of the filament passing through the two U-shaped porcelain pieces is 0°, and 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 the speed of the roller I is increased 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;

[0110] Since the cooling air temperature is as high as 23℃, at this time, the pressure sensor detects that the pressure value of the filament borne by the first U-shaped porcelain piece is 240 cN in real time, then it is found through comparison with the pressure setting range that the pressure feedback by the pressure sensor is less than 252 cN, then the second U-shaped porcelain piece is controlled to move, the angle of the filament passing through the two U-shaped porcelain pieces is 16°, and the pressure value detected by the pressure sensor is 252 cN.

[0111] The dyeing M rate of the oil-free drawing FDY fiber prepared after adjusting the position of the second U-shaped porcelain piece is 99.7%, and the dyeing uniformity is 4-5 levels.

[0112] Embodiment 8

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

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

[0115] wherein the pressure setting range is 215±11 cN, the tension of the fiber between the roller I and the roller II is set to be 8±1 cN, the spinning temperature is 292℃, the cooling air temperature is 21℃, the vertical distance from the spinneret face to the oil nozzle is 110 cm, the pre-networking pressure is 0.012 MPa, the roller I speed is 1700 m / min, the roller II speed is 1715 m / min, the roller II temperature is 70℃, the roller III speed is 1800 m / min, the roller III temperature is 75℃, the roller IV speed is 4700 m / min, the roller IV temperature is 135℃, the roller V speed is 4700 m / min, the roller V temperature is 135℃, the roller VI speed is 4710 m / min, the roller VII speed is 4720 m / min, the main networking pressure is 0.38 MPa, the winding speed is 4700 m / min, and the oil concentration at the time of oiling is 19.0 wt%;

[0116] The opening direction of the first U-shaped porcelain piece and the second U-shaped porcelain piece is opposite; the second U-shaped porcelain piece is located below the first U-shaped porcelain piece, and the roller I is located below the two U-shaped porcelain pieces;

[0117] The number of the first U-shaped porcelain pieces and the second U-shaped porcelain pieces is 24 respectively, 24 first U-shaped porcelain pieces and 24 second U-shaped porcelain pieces are fixed on the respective U-shaped porcelain piece guide frame, and the 24 first U-shaped porcelain pieces and the 24 second U-shaped porcelain pieces correspond one by one; the two U-shaped porcelain piece guide frames are parallel to each other;

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

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

[0120] One end of the U-shaped porcelain piece guide frame for fixing the first U-shaped porcelain piece is provided 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, a transmission shaft I of the servo motor I is connected to a pinion, the pinion is engaged with a gear, and the gear is connected with the guide frame of the second U-shaped porcelain piece; the central axis of the gear is parallel to the U-shaped porcelain piece guide frame;

[0121] A tension detection sensor is arranged between the roller I and the roller II, and the tension detection sensor is used for detecting the tension of the fiber between the roller I and the roller II;

[0122] 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 a transmission shaft II of the motor II is connected to the roller I;

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

[0124] When the transmission shaft I of the servo motor I drives the second U-shaped porcelain piece to displace, the angle of the filament bundle passing through the two U-shaped porcelain pieces is 0°, and 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, the control instrument II controls the tension detection sensor to start, and the speed of the roller I is increased 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 the spinning assembly is replaced, the preheating temperature of the spinning assembly is 332℃, at this time, the pressure sensor detects the pressure value of the filament borne by the first U-shaped porcelain piece in real time, which is 156 cN, then it is found through comparison with the pressure setting range that the pressure feedback by the pressure sensor is less than 204 cN, then the second U-shaped porcelain piece is moved, so that the angle of the filament bundle passing through the two U-shaped porcelain pieces is 30°, and the pressure value detected by the pressure sensor is 204 cN.

[0126] After the spinning assembly is replaced, the dyeing M rate of the oil-free drawing FDY fiber prepared after the new head is formed is 99.5%, and the dyeing uniformity is 4-5 levels.

Claims

1. A method for improving the dyeing uniformity of oil-free drawn FDY fiber, the production process of the oil-free drawn FDY fiber being: metering pump melt extrusion → cooling → spinning pre-network bunching → first U-shaped porcelain piece → second U-shaped porcelain piece → roller I → roller II → roller III → roller IV → roller V → oiling → roller VI → main network → roller VII → winding into shape, the opening directions of the first U-shaped porcelain piece and the second U-shaped porcelain piece being opposite, characterized in that: The pressure sensor is used to detect the pressure of the first U-shaped porcelain piece in real time, and the pressure setting range is compared with the received pressure value, and the second U-shaped porcelain piece is controlled to displace according to the comparison result, so that the angle of the yarn through the two U-shaped porcelain pieces changes, so that the pressure of the yarn borne by the first U-shaped porcelain piece returns to the set range. ​ The pressure setting range is interval [a, b], when the pressure feedback by the pressure sensor is less than the pressure a, the second U-shaped porcelain piece is controlled to move, so that the angle of the yarn through the two U-shaped porcelain pieces becomes 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, the second U-shaped porcelain piece is controlled to move, so that the angle of the yarn through the two U-shaped porcelain pieces becomes smaller, until the detected pressure reaches the pressure setting range. The number of the first U-shaped porcelain pieces and the second U-shaped porcelain pieces is multiple, respectively, the multiple first U-shaped porcelain pieces and the multiple second U-shaped porcelain pieces are fixed on the respective U-shaped porcelain piece guide frame, and the multiple first U-shaped porcelain pieces and the multiple second U-shaped porcelain pieces are one-to-one corresponding; one end of the U-shaped porcelain piece guide frame for fixing the first U-shaped porcelain piece is provided with a pressure sensor, the pressure sensor is connected with a control instrument I through a wire, the control instrument I is connected with a frequency converter I through a wire, the frequency converter I is connected with a servo motor I through a wire, a transmission shaft I of the servo motor I is connected with a pinion, the pinion is engaged with a gear, and the gear is connected with a guide frame of the second U-shaped porcelain piece. A tension detection sensor is arranged between the roller I and the roller II, and the tension detection sensor is used to detect the tension of the yarn between the roller I and the roller II; the tension detection sensor is connected with a control instrument II through a wire, the control instrument II is connected with a frequency converter II through a wire, the frequency converter II is connected with a motor II through a wire, and a transmission shaft II of the motor II is connected with 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 porcelain piece to displace, so that the angle of the yarn through the two U-shaped porcelain pieces is 0°, and the pressure feedback by the pressure sensor is still greater than b, the control instrument I sends a signal to the control instrument II, the control instrument II controls the tension detection sensor to start, and the speed of the roller I is increased 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, until the tension of the yarn between the roller I and the roller II reaches the tension setting range.

2. A method of improving dyeing uniformity of oil-free drawn FDY fiber as claimed in claim 1, wherein, The angle of the yarn through the two U-shaped porcelain pieces refers to the angle between the yarn and the vertical direction between the first U-shaped porcelain piece and the second U-shaped porcelain piece; when the second U-shaped porcelain piece does not displace, the angle of the yarn through the two U-shaped porcelain pieces is 5°-15°; when the second U-shaped porcelain piece displaces, the angle of the yarn through the two U-shaped porcelain pieces changes in the range of 0°-30°.

3. A method of improving dyeing uniformity of oil-free drawn FDY fiber according to claim 2, characterized in that, The two U-shaped porcelain piece guide frames are parallel to each other; the central axis of the gear is parallel to the U-shaped porcelain piece guide frame.

4. A method of improving dyeing uniformity of oil-free drawn FDY fiber according to claim 3, characterized in that, When the angle of the yarn through the two U-shaped porcelain pieces is 5°-15°, the angle of the yarn between the second U-shaped porcelain piece and the roller I and the vertical direction is also 5°-15°.

5. A method of improving dyeing uniformity of oil-free drawn FDY fiber as claimed in claim 1 wherein, The pre-network pressure is 0.015±0.03 MPa, the main network pressure is 0.4±0.02 MPa; the oil agent concentration is 20±1 wt% when oiling.

6. A method of improving dyeing uniformity of oil-free drawn FDY fiber as claimed in claim 1 wherein, The roller I speed is 1700-1800 m / min, the roller II speed is 1710-1810 m / min, the roller III speed is 1800-1900 m / min, the roller IV speed is 4100-4700 m / min, the roller V speed is 4100-4700 m / min, the roller VI speed is 4110-4710 m / min, the roller VII speed is 4115-4720 m / min, and the winding speed is 4100-4700 m / min.

7. A method of improving dyeing uniformity of oil-free drawn FDY fiber as claimed in claim 1 wherein, The dyeing M rate of the oil-free drawing FDY fiber is ≥99.5%, and the dyeing uniformity is above grade 4-5.

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