A method for controlling the tension of a raw wire

Abstract

A kind of tension control method of raw silk unwinding, comprising the following steps, step one, according to the detection result of tension detection device, according to the detection structure of tension detection device, the position corresponding to tension rod is known, according to the position of tension rod, the position-velocity correction coefficient KH corresponding to the position of tension rod is calculated;Step two, according to the detection result of tension detection device, according to the detection structure of tension detection device, the position corresponding to tension rod is known, so as to calculate the offset of tension rod in unit time, calculate the diameter correction coefficient Kd according to the offset, then calculate the reel diameter of reel according to diameter correction coefficient Kd;Step three, according to the full-line reference speed of raw silk unwinding, tension rod position speed correction coefficient, reel diameter, control reel speed.

Description

Technical Field

[0001] This invention belongs to the technical field of unwinding methods for raw yarn, and specifically relates to a tension control method for unwinding raw yarn. Background Technology

[0002] Polyacrylonitrile-based carbon fiber precursor fiber, also known as polyacrylonitrile-based carbon fiber precursor fiber, refers to the raw material fiber used to manufacture polyacrylonitrile-based carbon fiber. Tension control is a technology for automatically controlling the tension on a processed material that is continuously moving or stationary between two processing machines. Tension is a very important control parameter in carbon fiber production. In carbon fiber production, the movement of the fiber bundle is caused by the drawing action of different traction machines. The difference in surface linear velocity between the front and rear traction machines creates tension in the fiber bundle. Excessive tension can cause the fiber bundle to break, while insufficient tension can cause the fiber bundle to become too loose and misalignment. Unstable tension can easily lead to static electricity and "fuzz" damage to the fiber bundle.

[0003] Currently, the commonly used tension control methods on the market include the following: (1) Using "position sensor + variable frequency motor speed control mode + open loop control" to control the tension of the raw yarn. The disadvantages of this tension control method are: 1) The variable frequency motor reduces tension changes by tracking the speed of the downstream drawing machine. Due to the cumulative deviation, the tension control effect is not good; 2) The "position sensor" does not directly measure the yarn tension, but detects the outer diameter of the raw yarn spool, thereby correcting the speed of the variable frequency motor and compensating for the linear speed. Due to the cumulative deviation, the tension control effect is not good; 3) The linear speed setting of the variable frequency motor tracks the reference speed * drawing coefficient, which is an open loop control. According to the actual tension situation on site, the drawing coefficient is manually adjusted to control the tension. The tension is easy to deviate from the target value; 4) In case of sudden situations such as yarn breakage, yarn entanglement, or fuzz, there is no emergency response mechanism, which may cause dangerous situations such as reduced output or even equipment damage. (2) The tension of the raw yarn is controlled by “position sensor + magnetic powder brake + open loop control”. The disadvantages of this tension control method are: 1) The magnetic powder brake maintains a fixed resistance. Due to the low accuracy, the tension control effect is not good; 2) The “position sensor” does not directly measure the yarn tension, but detects the outer diameter of the raw yarn roll to correct the output of the magnetic powder brake. Due to the cumulative deviation, the tension control effect is not good; 3) The torque of the magnetic powder brake is set to the full load initial value * roll diameter coefficient. In fact, it is an open loop control. According to the actual tension on site, the resistance is manually adjusted to control the tension. The tension is easy to deviate from the target value; 4) There is an emergency response mechanism in case of sudden situations such as yarn breakage, yarn entanglement, and fuzz. (3) The tension of the raw yarn is controlled by a special winding machine. The special yarn winding equipment adopts the method of “tension rod + stepper motor + special controller”. The disadvantages of this tension control method are: 1) High cost; 2) Special equipment, which requires high technical skills from maintenance personnel and is difficult to maintain; 3) Strict requirements on the weight of the yarn roll. Summary of the Invention

[0004] To address the above shortcomings, the technical problem to be solved by the present invention is to provide a tension control method for unwinding raw yarn, which is used to control the tension to be constant during the unwinding process of raw yarn, simplify the tension control method, and reduce the production cost of yarn loading equipment.

[0005] To solve the above technical problems, the technical solution adopted by the present invention is as follows:

[0006] A method for controlling the tension of unwinding raw yarn includes the following steps:

[0007] Step 1: Calculate the position-velocity correction coefficient KH corresponding to the position of the tension rod based on the detection results of the tension detection device;

[0008] Step 2: Calculate the roll diameter correction factor Kd based on the detection results of the tension detection device, and then calculate the roll diameter of the trolley roll.

[0009] Step 3: Control the speed of the control trolley based on the baseline speed of the entire unwinding process of the raw yarn, the speed correction coefficient of the tension bar position, and the trolley reel diameter.

[0010] As a preferred embodiment of the present invention, the tension detection device includes a tension rod for measuring tension. The tension rod moves up and down due to the unwinding action of the raw yarn, and the tension of the unwinding of the raw yarn is determined by the amount of up and down movement.

[0011] In a preferred embodiment of the present invention, the speed correction coefficient KH is set at the 50% position of the tension rod movement, and the tension rod is positioned between 50% and 100% of its movement. When the tension bar is in the 0%-50% position,

[0012] In a preferred embodiment of the present invention, when the tension bar is above 50%, an interlocking stop occurs when the tension bar is above 80%. 上半段常数 =0.036; When the tension bar is below 50%, an interlocking stop occurs when the tension bar is below 20%, K 下半段常数 =0.25; when the tension bar is at the 50% position, the speed correction factor KH = 100%.

[0013] As a preferred embodiment of the present invention, the formula for calculating the diameter of the trolley reel is as follows: D 台车卷轴外径 =D0 台车卷轴初始值 ×Kd 台车卷径修正系数 .

[0014] As a preferred embodiment of the present invention, the roll diameter correction formula is as follows: roll diameter correction coefficient Kd = roll diameter correction coefficient Kd + tension bar offset value × 0.1, where the tension bar offset value is the deviation between the middle position of the tension bar and the current position of the tension bar within 500ms.

[0015] In a preferred embodiment of the present invention, in step three, the rotational speed of the trolley servo motor is calculated based on the fact that the speed of the trolley winding axis is consistent with the reference speed of the entire line.

[0016] As a preferred embodiment of the present invention, the linear velocity of the trolley reel is calculated based on the speed change of the No.1 drive device downstream of the tension detection device, combined with the speed correction coefficient corresponding to the position change of the tension rod.

[0017] As a preferred embodiment of the present invention, the trolley speed control formula is as follows.

[0018]

[0019] As a preferred embodiment of the present invention, the tension detection device is calibrated before step one. The calibration steps are as follows.

[0020] S1, raise the tension bar until it reaches the upper limit position, and record the raw data MAX from the angle sensor;

[0021] S2, lower the tension bar until it reaches the lower limit, and record the raw data MIN from the angle sensor;

[0022] S3 converts the raw angle sensor data between MIN and MAX into data between 0 and 100.0%.

[0023] S4. If the data when the tension rod reaches the upper limit is less than the data when it reaches the lower limit (i.e., MAX > MIN), then the installation direction of the angle sensor needs to be adjusted, or the data needs to be reversed in the data conversion process.

[0024] The beneficial effects of the present invention are: (1) The tension control method introduces position-speed correction coefficient and roll diameter correction coefficient to eliminate tension changes caused by changes in trolley diameter and tension rod position, thereby ensuring the control accuracy of the tension control method.

[0025] (2) The tension change is calculated by detecting the position change of the up-and-down floating tension bar. The tension detection method is simpler, the tension is more stable than the control scheme without the roll diameter sensor, and the control scheme with the roll diameter sensor is more economical. Attached Figure Description

[0026] Figure 1 This is the control principle diagram of the equipment corresponding to this tension control method.

[0027] Figure 2 This is a graph showing the relationship between the position of the tension bar and the KH velocity correction factor.

[0028] Figure labels: 1. Raw yarn trolley; 2. Tension detection device; 3. No.1 drive device; 4. Tension bar. Detailed Implementation

[0029] The present invention will now be further described with reference to the accompanying drawings.

[0030] This tension control method is based on a raw yarn winding device, which includes at least a raw yarn trolley 1, a tension detection device 2, and a No.1 drive device 3. The raw yarn trolley 1 is driven by a servo motor, rotating a single raw yarn spool and responsible for adjusting the tension of the yarn bundles on the trolley 1. The tension detection device 2 detects the tension generated on the raw yarn in this device. The No.1 drive device 3, driven by a servo motor and located downstream of the tension detection device 2, pulls all the raw yarn bundles. The speed of the No.1 drive device 3 is the reference speed for the entire line. In this embodiment, the tension on the yarn is controlled by controlling the rotational speed of the servo motor in the raw yarn trolley 1.

[0031] In this embodiment, in order to reduce the production cost of the raw yarn winding equipment, the tension detection device 2 includes a tension rod 4 that can float up and down. An angle sensor is used to detect the position of the floating wheel (0%-100%) and transmit it to the controller of the device. The position of the tension rod is positively correlated with the tension of the yarn bundle.

[0032] The position of tension rod 4 indirectly reflects the magnitude of the tension of the filament bundle. The position of tension rod 4 is easier to detect and calibrate, which simplifies the tension control method. (1) When the tension rod is at the upper limit, the tension is the greatest and there is a risk of filament breakage. (2) When the tension rod is at the lower limit, the tension is the smallest and there is no tension on the filament bundle, which may lead to filament breakage. (3) When the tension rod is stable in the middle position, the tension of the filament bundle is moderate and the motor speeds of the raw filament trolley 1 and No.1 drive device 3 are also suitable. (4) When the floating wheel is at a higher position, the tension of the filament bundle is too large and the speed of the trolley reel motor in the raw filament trolley 1 is too small. (5) When the floating wheel is at a lower position, the tension of the filament bundle is too small and the speed of the trolley reel motor in the raw filament trolley 1 is too large. Different states reflect different tension conditions of the filament bundle.

[0033] A method for controlling the tension of unwinding raw yarn includes the following steps:

[0034] Step 1: Based on the detection results of the tension detection device, the position of tension rod 4 can be determined according to the detection structure of the tension detection device. Based on the position of tension rod 4, the position-velocity correction coefficient KH corresponding to the position of tension rod is calculated.

[0035] Step 2: Based on the detection results of the tension detection device, the position of the tension rod 4 can be determined according to the detection structure of the tension detection device. Then, the offset of the tension rod 4 per unit time is calculated. The roll diameter correction coefficient Kd is calculated based on the offset, and then the roll diameter of the trolley roll is calculated based on the roll diameter correction coefficient Kd.

[0036] Step 3: Control the speed of the control trolley based on the baseline speed of the entire unwinding process of the raw yarn, the speed correction coefficient of the tension bar position, and the trolley reel diameter.

[0037] (I) The calculation steps for the position-velocity correction coefficient KH corresponding to the position of the tension bar are as follows.

[0038] First, determine the position of the tension bar.

[0039] 1. When the tension is moderate, the "position-velocity correction coefficient" is equal to 1.0, meaning no correction is made;

[0040] 2. When the tension is too high, the "position-speed correction coefficient" is greater than 1.0, meaning that the motor accelerates after correction; the greater the tension, the greater the "position-speed correction coefficient", and the faster the motor.

[0041] 3. When the tension is too low, the "position-speed correction coefficient" is less than 1.0, meaning that the motor decelerates through correction; the lower the tension, the smaller the "position-speed correction coefficient", and the slower the motor.

[0042] 4. When tension bar 4 is at the upper or lower limit, the interlocking stop logic is triggered after a delay of 3 to 5 seconds to protect production safety.

[0043] Based on the above control rules, the following table was created, and multiple fitting curves were plotted and tested based on the table.

[0044]

[0045] After performance testing, the function of squared deviation showed better control effect. Therefore, in this embodiment, the position-velocity correction coefficient KH is a function of squared deviation. The relationship between the position-velocity correction coefficient KH and the position of the tension bar is shown in the figure below. Figure 2 As stated above.

[0046] The formula for calculating the position-velocity correction factor KH is as follows:

[0047] 1. When the tension bar position is above 50%, the floating roller is interlocked above 80%. The correction factor before interlocking is 350%. In this embodiment, the reference value of the correction factor before interlocking is 350%. In the specific control process, the correction factor before interlocking can be adjusted according to actual needs.

[0048] 80% position:

[0049] 50% position:

[0050]

[0051] 50%–80% position:

[0052] 2. When the tension bar position is below 50%, the floating roller is interlocked below 20%, and the correction factor for the 0% position is 0%.

[0053] 0% position:

[0054] 50% position:

[0055]

[0056] 0% to 50% position:

[0057] 3. When the tension bar position is 3.50%, the correction factor is 100%.

[0058] (ii) The calculation steps for calculating the trolley reel diameter based on the position of the tension bar are as follows.

[0059] As production progresses, the amount of raw filament on the trolley reel decreases, and the reel diameter decreases until it is approximately equal to the inner diameter of the reel. The formula for calculating the trolley reel diameter is as follows.

[0060] D 台车卷轴卷径 =D0 台车卷轴初始值 ×Kd 台车卷径修正系数 .

[0061] In this embodiment, D0 台车卷轴初始值 The initial value of the outer diameter of the trolley reel is a constant, usually chosen as half of the maximum outer diameter. When the maximum outer diameter is φ800.0mm, it is φ400.0mm.

[0062] By calculating Kd 台车卷径修正系数 The true diameter of the trolley reel can be obtained, and the diameter correction factor Kd is within Kd. 台车卷径修正系数 Based on this, the positional deviation of the tension bar is accumulated and processed to obtain the following specific algorithm:

[0063] First, set the baseline value for calculating the roll diameter; when the tension bar is stable at the middle position (50.0%), the roll diameter is φ400mm (roll diameter correction factor Kd = 100%). After threading, when the tension bar is in the lower limit area, the roll diameter correction factor Kd = 100.0%; when the threading system starts running, the initial value of the roll diameter correction factor is 100%, and the roll diameter calculated at this time is the initial roll diameter (φ400.0mm);

[0064] During the operation of the yarn feeding system, the positional deviation of the tension bar is added to the roll diameter correction factor Kd every 500ms. The roll diameter correction factor Kd is then adjusted every 500ms.

[0065] Roll diameter correction factor Kd = Roll diameter correction factor Kd + Tension bar offset value × 0.1, where the tension bar offset value is the tension bar mid-position - tension bar current position.

[0066] The range of the roll diameter correction factor Kd: Max: 200.0% (φ800.0mm),

[0067] Min: 38.2% (153.0 mm) (inner diameter of the raw yarn roller).

[0068] (III) The control algorithm for the speed of the servo motor of the console car is as follows.

[0069] The tension of the filament bundle can be adjusted by the speed of the upstream and downstream drive rollers; the speed difference creates tension in the filament bundle. Since the downstream No.1 drive speed is not used for tension control, the tension of the corresponding filament bundle is stabilized by changing the rotation speed of the trolley servo motor.

[0070] 1. As the speed of the trolley drive shaft increases, the tension of the filament bundle decreases and becomes non-linear, at which point the tension bar tends to descend;

[0071] 2. As the speed of the trolley drive shaft decreases, the tension of the filament bundle increases and becomes non-linear, causing the tension rod floating wheel to show an upward trend;

[0072] 3. Ignoring the effects of filament slippage and its own deformation, when the speeds of the trolley drive shaft and the No.1 drive shaft are the same, the filament tension remains basically unchanged, and the position of the tension rod remains unchanged;

[0073] 4. When the tension bar float wheel is at the 50% midpoint, the filament tension is equal to the design preset tension.

[0074] Adjust the counterweight of the tension bar to stabilize it at the 50% midpoint. By using the above method, tension detection is converted into relatively easy position detection. When the tension bar is stable at the 50% midpoint, the tension of the filament bundle is the tension that needs to be controlled. The requirement to control the tension of the filament bundle is transformed into controlling the floating wheel of the tension bar to stabilize at the 50% midpoint.

[0075] To stably control the tension of the filament bundle, the speed of the trolley reel needs to follow the speed changes of the No.1 drive, and the speed needs to be compensated according to the changes in the position of the tension bar floating wheel, as shown in the following formula:

[0076] V 台车卷轴线速度 =f(V No.1驱动装置线速度 f(H) 张力杆位置 ))=V No.1驱动装置线速度 ×KH 位置-速度补偿系数

[0077] Cart winding axis speed = Cart winding axis speed * Cart winding axis circumference

[0078]

[0079]

[0080]

[0081]

[0082]

[0083] Based on the relationship between the trolley winding axis speed, the linear speed of the No.1 drive unit, and KH (position-speed compensation coefficient), the formula is derived as follows:

[0084]

[0085]

[0086] Because the outer diameter of the trolley reel is not fixed and varies greatly, the diameter of the raw yarn reel is largest in the early stages of production (e.g., φ800.0mm). As production progresses, the amount of raw yarn on the reel decreases, and the reel diameter decreases until it is approximately equal to the inner diameter of the reel. Therefore, the influence of the reel diameter needs to be considered during the trolley reel speed control process.

[0087] Based on the calculation method for the trolley reel diameter, the trolley reel diameter correction factor is substituted into the above formula, and the derivation is as follows:

[0088]

[0089] in, For constant terms;

[0090] VSD No.1装置线速度 Set the speed for the operator;

[0091] KH 位置-速度补偿系数 It is a function of the position variable of the tension bar;

[0092] Kd 台车卷径修正系数 The calculation is based on the position of the tension bar floating wheel.

[0093] (iv) Before using the tension detection device, it is necessary to calibrate it. The calibration steps are as follows.

[0094] S1, raise the tension bar until it reaches the upper limit position, and record the raw data MAX from the angle sensor;

[0095] S2, lower the tension bar until it reaches the lower limit, and record the raw data MIN from the angle sensor;

[0096] S3 converts the raw angle sensor data between MIN and MAX into data between 0 and 100.0%.

[0097] S4. If the data when the tension rod reaches the upper limit is less than the data when it reaches the lower limit (i.e., MAX > MIN), then the installation direction of the angle sensor needs to be adjusted, or the data needs to be reversed in the data conversion process.

[0098] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention; therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

[0099] Although this document makes extensive use of terms corresponding to the figure labels, the possibility of using other terms is not excluded; these terms are used merely to more conveniently describe and explain the essence of the invention; interpreting them as any kind of additional limitation would be contrary to the spirit of the invention.

Claims

1. A method for controlling the tension of unwinding raw yarn, characterized in that, Includes the following steps, Step 1: Calculate the position-velocity correction coefficient KH corresponding to the position H of the tension rod based on the detection results of the tension detection device; The tension detection device includes a tension rod for measuring tension. The tension rod moves up and down due to the unwinding of the raw yarn, and the tension of the unwinding of the raw yarn is determined by the amount of up and down movement. An angle sensor is used to detect the position of the tension rod floating wheel. The raw data from the angle sensor is converted into data between 0% and 100%, which is recorded as the tension rod position H. The position-velocity correction factor KH is set at the 50% mark of the tension bar's movement. When the tension bar is between 50% and 100% of its movement... K 上半段常数 =0.036, when the tension bar is in the 0%-50% position, K 下半段常数 =0.25, when the tension bar is at the 50% position, KH = 100%; When the tension bar is above 50%, an interlocking stop occurs when the tension bar is above 80%; when the tension bar is below 50%, an interlocking stop occurs when the tension bar is below 20%. Step 2: Calculate the roll diameter correction factor Kd based on the detection results of the tension detection device, and then calculate the roll diameter D of the trolley roll. The initial value of the roll diameter correction factor Kd is 100%. With a cycle of 500ms, the position deviation of the tension bar is added to the roll diameter correction factor Kd. The roll diameter correction factor Kd is adjusted every 500ms. The calculation formula for the roll diameter correction factor Kd is Kd=Kd1+(50%-H)×0.1, where Kd1 is the roll diameter correction factor of the previous cycle. The formula for calculating the diameter D of the trolley reel is D = D0 × Kd, where D0 is the initial value of the outer diameter of the trolley reel; Step 3: Based on the linear speed VSD of the No.1 drive device for unwinding the raw yarn, the position-speed correction coefficient KH, the trolley reel diameter D, and the reduction ratio i, control the rotational speed nsd of the trolley servo motor. The formula for calculating the servo motor speed NSD of the trolley is: .

2. The tension control method for unwinding raw yarn according to claim 1, characterized in that, Before step one, the tension detection device needs to be calibrated. The calibration steps are as follows: S1, raise the tension bar until it reaches the upper limit position, and record the raw data MAX from the angle sensor; S2, lower the tension bar until it reaches the lower limit, and record the raw data MIN from the angle sensor; S3 converts the raw angle sensor data between MIN and MAX into data between 0 and 100.0%. S4. If the original angle sensor data MAX when the tension rod reaches the upper limit is less than the original angle sensor data MIN when the tension rod reaches the lower limit, then the installation direction of the angle sensor needs to be adjusted.

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