Method for controlling the winding density of a yarn on a slack warper

Abstract

The application discloses a yarn winding density control method of loose warping machine, wherein the radial movement of the yarn pressing roller is controlled according to the accumulated rotation angle of the warp beam, and the radial movement of the yarn pressing roller is controlled in the unit of the minimum driving pulse of the radial driving device of the yarn pressing roller; the control method comprises a uniform increment method or a segmented uniform increment method, and can realize the slow backward movement of the yarn pressing roller at a uniform speed according to the wound yarn amount or the accumulated winding rotation angle, so as to ensure the constant winding pressure of the warp yarn and the uniform density of the warp yarn, and the density is not affected by the measurement error or fluctuation of the traditional pressure or displacement.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of textiles, and particularly relates to a yarn winding density control method for a slack warping machine. BACKGROUND

[0002] The slack warping machine is used to wind a certain number of warp yarns in parallel and uniformly on a warping beam according to a specified length. During warping, the warp yarns need to have appropriate tension while maintaining the strength and elasticity of the warp yarns as much as possible. The tension of the warp yarns should be as uniform as possible during the warping process, and the winding density of the warp yarns on the warping beam should be uniform, and the surface of the warping beam should be round and regular without concave-convex unevenness.

[0003] Controlling the uniform winding density is very important for the subsequent dyeing process. Non-uniform density can easily lead to uneven dyeing, non-uniform dyeing, and even waste products due to dyeing explosion. The traditional warping machine is composed of a machine head, a box tooth seat, and a group of beam creels. The main control method is that the beam yarn is wound onto the warping beam, and the winding density is realized by controlling the pressure of the pressure roller. Due to the influence of speed, humidity, and temperature during warping, the tension of the yarn changes, and the density is formed by the combined action of the pressure of the yarn pressure roller and the tension of the yarn. The density changes with the changes of speed, temperature, and humidity. The pressure method controls the density, and the error is large and the adaptability is poor. Therefore, this method is prone to problems such as non-uniform winding density, difficulty in accurate control, low work efficiency, and quality not meeting the technical requirements, which cannot meet the requirements of customers. In particular, this method cannot meet the requirements of slack dyeing beam and high-technology warping. SUMMARY

[0004] In view of the above problems, the present application designs a yarn winding density control method for a slack warping machine. The winding density is controlled by the radial displacement step of the pressure roller. The method is more simple, has fewer related factors, and can realize accurate control of the winding density.

[0005] The yarn winding density control method for the slack warping machine designed by the present application controls the radial movement of the yarn pressure roller according to the cumulative rotation angle of the warping beam, and controls the radial movement of the yarn pressure roller in units of the minimum driving pulse of the yarn pressure roller radial driving device. The present application improves the traditional pressure feedback control to warping beam rotation angle control, which can gradually increase the radial precession amount of the yarn pressure roller (relative to the radial direction of the warping beam) by the minimum pulse of the yarn pressure roller radial movement motor, so that the distance between the yarn pressure roller and the warping beam changes with the amount of wound warp yarns. The control method includes a uniform incremental method or a segmented uniform incremental method.

[0006] The uniform incremental method regards the winding of each yarn on the warping beam as a process of uniform increase of the radius with the rotation angle, that is, the radius of each layer of yarn is uniformly increased by a fixed amount for one revolution, and the timing of issuing a single precession pulse of the yarn pressure roller is determined according to the change in the rotation angle and the rate of change of the radius with the angle.

[0007] The segmented uniform speed incremental method treats the winding of each yarn on the warp beam as a process in which the radius increases uniformly with the rotation angle in segments. That is, after each layer of yarn is wound a certain number of times, the radius increases uniformly before entering the next layer of winding. Based on this, the timing of the single radial advance pulse of the pressure roller is determined according to the change in rotation angle, the number of windings in the same layer, and the rate of change of radius between adjacent layers with the angle.

[0008] Furthermore, the uniform incremental method, also known as the continuous Archimedean spiral incremental method, includes the condition that the system issues the i-th pulse adjustment, provided that:

[0009] Δr=Δr θ *θ=i*Δr min Formula (1)

[0010] Where Δr is the radius increment, Δr θ The radius is the rate of change of angle, θ is the cumulative rotation angle of the warp beam around the yarn, and Δr is the measured value; min The minimum radial distance of the pressure roller driven by a single drive pulse; i = 1, 2, 3, ..., n max n max The maximum number of precession pulses, i.e., the cumulative number of pulses emitted n. max The key is that the timing of each precession pulse is precisely controlled. Each time the measured angle value meets the condition of formula (1), the system issues a precession pulse, and the pressing roller retracts radially by Δr. min ,

[0011] n max =int((r max -r0) / Δr min )

[0012] Here, int() is the floor function. The system starts from the beginning of the yarn winding process, with the radius of the empty warp beam being r0 and the radius of the fully wound warp beam being r. max ;

[0013] Yarn count N e (British yarn count, abbreviated as English count, 583.1 / Ne is the yarn count number, the unit is g / km, that is, the weight of yarn per kilometer. This invention uses 0.5831 / Ne, the unit is g / m), the number of yarns wound synchronously is N, the axial length of the warp beam is a, the set density is ρ, and the total number of turns of a single yarn after it is fully wound is q. max Then we have:

[0014] Δr θ =(r max -r0) / (2πq max )=0.5831N / (2πaρN e ) Formula (2)

[0015] Further, the segmented uniform increment method, also known as segmented Archimedes spiral increment method, comprises calculating the average cross-sectional area S of the single yarn in the beam according to the single yarn in the beam min The transverse size d of the single yarn in the beam with winding density p can be obtained, and the number of yarns n with the same radius in the same layer can be obtained according to the axial length a of the beam and the total number of yarns N r ,

[0016] n r =a / (N*d)

[0017] Then the change rate of the segmented radius with the angle is

[0018] Δr θ =(r max -r0) / (2πq max n r )=0.5831N / (2πaρn r N e ) Formula (3)

[0019] When the measured angle θ satisfies the following formula,

[0020]

[0021] The system sends the ith presser roll precession pulse, so that the radial distance of the presser roll relative to the beam increases Δr min ;

[0022] Wherein, i=1, 2, 3, …, n max , n max is the maximum precession pulse number, and mod(θ, 2π) is the θ modulo 2π remainder function.

[0023] Further, the single yarn transverse size d calculation method comprises an equivalent circle diameter calculation method, that is, the average effect of each coil of the single yarn after winding on the cross-sectional space along the axial direction of the beam is equivalent to a circle, and has

[0024] d=2sqrt(S min / π)

[0025] Wherein, sqrt() is the square root operation; the equivalent mode is based on the fact that the cross section of the wound yarn is closer to a circle.

[0026] Further, the single yarn transverse size d calculation method comprises an equivalent square calculation method, that is, the average effect of each coil of the single yarn after winding on the cross-sectional space along the axial direction of the beam is equivalent to a square, and has

[0027] d=sqrt(S min )

[0028] This equivalent method is based on the fact that the wound yarn fills the winding space of the warp beam, while the circular equivalent method has gaps between adjacent circles.

[0029] Furthermore, the initial distance between the warp beam and the surface of the pressure roller is greater than or equal to the radial dimension L of the single yarn, and less than or equal to 5Δr. min .

[0030] Furthermore, the radial dimension of the single yarn L = 2sqrt(S) min / π), which is consistent with the calculation method of the transverse dimension d of the single yarn, that is, the diameter obtained by the equivalent circle calculation method, or L is the diameter of the unwound bare yarn.

[0031] Furthermore, the radial dimension of the single yarn L = sqrt(S min The method for calculating the transverse dimension d of a single yarn is consistent with that for calculating the diameter using the equivalent square method.

[0032] Furthermore, after the warp beam is fully wound with yarn, the pressure roller remains in its final position while the warp beam continues to rotate for at least a specified number of turns.

[0033] Furthermore, the initial distance between the warp beam and the surface of the pressing roller is Δr. min The first pulse precession is implemented first, leaving space for the yarn to begin winding. Theoretically, the winding density of the reserved space is ρ. The control method includes the following steps:

[0034] S1. Set the initial winding distance between the pressure roller and the empty warp beam;

[0035] S2, yarn winding, measuring the cumulative rotation angle of the warp beam;

[0036] S3. Condition judgment: After the winding starts, the pressure roller is moved radially based on whether the warp beam rotation angle meets the condition for issuing the advance pulse. The condition judgment includes the condition judgment of formula (1) by the uniform speed increment method or the condition judgment of formula (4) by the segmented uniform speed increment method.

[0037] S4. Warp yarn roll setting: After the yarn is wound, the pressure roller maintains the distance from the warp beam, and the warp beam rotates continuously for no less than a specified number of turns, so that the yarn roll is set under continuous constant pressure.

[0038] The advantages and beneficial effects of this invention are as follows: The yarn winding density control method of the loose warping machine designed in this invention measures and controls the displacement of the pressure roller by measuring the rotation angle of the warp beam, and controls the radial movement of the pressure roller with a single precession pulse. This achieves high-precision control of the pressure roller displacement, thereby also achieving high-precision control of the warp beam yarn winding density, without the problems of density fluctuation and unevenness, and the density adjustment is more convenient and efficient. On the other hand, many warp beam rotation links have built-in angle encoders (such as rotary transformers). Even if an angle encoder is redesigned and installed, it is a mature technology, and the system does not have high requirements for encoder accuracy. A measurement level or even 10-level accuracy is sufficient. The system does not require pressure sensors and / or displacement sensors (displacement measurement feedback can also be retained), and the overall design is more convenient. Attached Figure Description

[0039] Figure 1 This is a flowchart illustrating the steps for controlling the yarn winding density of a loose-type warping machine. Detailed Implementation

[0040] The specific embodiments of the present invention will be further described below with reference to the accompanying drawings and examples. The following examples are only used to more clearly illustrate the technical solutions of the present invention and should not be construed as limiting the scope of protection of the present invention.

[0041] Example 1

[0042] This invention discloses a method for controlling the yarn winding density of a loose warping machine. The method controls the radial movement of the pressure roller based on the cumulative rotation angle of the warp beam, using the minimum drive pulse of the pressure roller radial drive device as the unit. This invention improves upon traditional pressure feedback control by using warp beam rotation angle control. This allows the pressure roller radial movement motor to gradually increase the radial advance (movement relative to the warp beam) of the pressure roller according to the minimum pulse, causing the distance between the pressure roller and the warp beam to vary with the amount of warp yarn wound. Since the measurement error of traditional pressure sensors often requires several or even dozens of winding turns to compensate, resulting in uneven winding density, calculating the radial advance of the pressure roller based on the winding angle or the amount of yarn wound allows the system to slowly and uniformly retract the pressure roller based on the amount of yarn wound or the cumulative winding rotation angle, even with changes that pressure or displacement sensors cannot measure. This ensures constant warp winding pressure and uniform density, unaffected by traditional pressure or displacement measurement errors or fluctuations. The control method described in this embodiment employs a uniform incremental method.

[0043] The uniform speed increment method treats the winding of each yarn on the warp beam as a process in which the radius increases uniformly with the rotation angle. That is, for each layer of yarn wound around once, the radius increases uniformly by a fixed amount. Based on this, the timing of the single radial precession pulse of the pressure roller is determined according to the change in rotation angle and the rate of change of radius with angle. The single precession pulse corresponds to the minimum radial precession of the pressure roller. In this embodiment, it is generally the radial retraction amount, which means that the radial distance between the pressure roller and the warp beam increases by a minimum amount that the system can control.

[0044] Preferably, the uniform incremental method is also called the continuous Archimedean spiral incremental method. Based on the Archimedean spiral equation, and assuming that the warp beam's winding radius r increases uniformly with the rotation angle, i.e.

[0045] r = b + cθ

[0046] Where b is the distance from the starting point of the winding to the origin of the polar coordinates, which is a constant; c is the rate of change of the radius with respect to the angle (the increment of the radius per radian), c = Δr θ This represents the increase in angle r of the helix for each additional unit.

[0047] Our goal is to determine the minimum radial distance Δr corresponding to a single driving pulse. min Calculate the radial precession Δr for each pulse-driven pulse. min The timing or corresponding rotation angle measurement value, that is, at what angle the warp shaft rotates continuously to, the system should issue a precession pulse command to minimize the radial retraction of the pressure roller by Δr. min .

[0048] The uniform incremental method includes the following condition as the system issues the i-th pulse for adjustment:

[0049] Δr=Δr θ *θ=i*Δr min Formula (1)

[0050] Where Δr is the radius increment, Δr θ The radius is the rate of change of angle (in this embodiment, the angle is measured in radians, so Δr) θ θ represents the cumulative rotation angle of the warp beam (representing the radius increment per radian), and is the measured value. Starting from the empty warp beam's initial winding point as 0, and measured in radians, the angle increases continuously. For a maximum measurement of 360 degrees using a warp beam rotation angle encoder, the measured angle value increases by 2π for each revolution. If a certain angle value exists at the initial winding point, only that angle value needs to be recorded as the zero value. Subtracting the zero value from subsequent measurements yields the measured angle. θ can be obtained using a shaft angle encoder installed on the warp beam rotor (in this embodiment, a rotary transformer is used as the angle encoder, emitting 1024 pulse signals per revolution, with each pulse having an accuracy of 0.35156 degrees); Δr minThe minimum radial movement distance of the pressure roller driven by a single drive pulse can be predetermined according to the system design. The radial drive mechanism of the pressure roller generally controls the radial movement of the pressure roller through the output current or voltage pulse of the motor. In this embodiment, one pulse of the stepper motor corresponds to a radial precession of 0.0393 mm for the pressure roller, i.e., Δr. min =0.0393mm, the stepper motor rotates once every 1000 pulses, and the radial advance of the pressure roller is 39.3mm; i = 1, 2, 3, ..., n max n max The maximum number of precession pulses, i.e., the cumulative number of pulses emitted n. max Each precession pulse is crucial, and the timing of each precession pulse must be precisely controlled. The actual measured angle value must meet the conditions of formula (1).

[0051] n max =int((r max -r0) / Δr min )

[0052] Here, int() is the floor function. The system starts from the beginning of the yarn winding process, with the radius of the empty warp beam being r0 and the radius of the fully wound warp beam being r. max ;

[0053] Yarn count N e (British yarn count, abbreviated as English count, 583.1 / Ne is the yarn count number, the unit is g / km, that is, the weight of yarn per kilometer, in this embodiment it is 0.5831 / Ne, the unit is g / m), the number of yarns wound synchronously is N, the axial length of the warp beam is a, the set density is ρ, and the total number of turns of a single yarn after the yarn is fully wound is q. max Then we have:

[0054] Δr θ =(r max -r0) / (2πq max )=0.5831N / (2πaρN e ) Formula (2)

[0055] Formula (2) is derived as follows:

[0056] Record the total length L of the synchronously wound single yarn. max Total weight of fully wound yarn (G) max , and N e 、N、ρ、r0、a、r max Δr min All parameters are known or derived; for the length L of a single wound yarn, there are corresponding warp beam radius r, cumulative warp beam rotation angle θ, and yarn weight G; for the change in yarn length ΔL, there are corresponding weight change ΔG and the resulting radius change Δr. All of these are measured or calculated values, and the following relationships exist:

[0057] The relationship between the total weight of N yarns of length L is as follows:

[0058] G = N * L * (0.5831 / N) e )

[0059] G max =N*L max *(0.5831 / N e )

[0060] ΔG=N*ΔL*(0.5831 / N e )

[0061] The density relationships are:

[0062] ρ=G max / (π(r max 2 -r0 2 a)

[0063] ρ=G / (π(r 2 -r0 2 a)

[0064] ρ=ΔG / (π((r+Δr) 2 -r 2 a)

[0065] The cross-sectional area S of a single yarn needs to be calculated. min (Cross-sectional area of ​​a single yarn as seen in a cross-section along the warp beam), this is the average cross-sectional area of ​​each yarn under a given winding density ρ of the warp beam; or calculate the number of turns q of a single yarn after it is fully wound. max Based on this, it can be calculated at what position the system should issue a radial precession pulse command for the pressure roller when the real-time angle θ rotates.

[0066] According to the principle of conservation of weight, we have:

[0067] 2πrS min ρ=2πr*(0.5831 / N e )

[0068] Therefore,

[0069] S min =(0.5831 / N) e ) / ρ

[0070] The total cross-sectional area S after the axis is fully wound max (The cross-sectional area of ​​all yarns on one side of the warp beam as seen in a cross-section along the warp beam's axial direction)

[0071] S max =a(r max-r0)

[0072] Then the total number of turns q of a single yarn on the warp beam max for

[0073] q max =S max / (NS min )=a(r max -r0)ρN e / (0.5831N)

[0074] Let q max When a single yarn is wound onto a warp beam, its radius increases uniformly. Although there may actually be multiple loops of yarn with the same radius, the influence of the radius change of a single loop of yarn is very small. In fact, the pressure roller only needs to advance a minimum radial retreat amount Δr after the warp beam has been wound several times. min Treating the influence of these several loops of yarn on the radius as a continuous incremental model or a staged continuous incremental model does not have a significant impact on the result, because ultimately a radial retraction pulse command of the pressure roller will only be generated after a certain number of loops.

[0075] Based on the relationship between the total radius increment after the yarn is fully wound (i.e., the sum of several precession increments) and the total rotation angle.

[0076] r max -r0=(2πq max )*Δr θ

[0077] Where, 2πq max The cumulative maximum rotation angle of the warp axis is given, thus formula (2) can be obtained.

[0078] During the warp winding process, each time the measured angle θ satisfies formula (1), the system sends a radial precession pulse to the pressure roller drive motor, driving the pressure roller to move radially backward by a minimum distance Δr. min until the warp axis is fully wound around r = r max .

[0079] Example 2

[0080] The difference from Example 1 is that the control method described in this example adopts the segmented uniform speed incremental method. The segmented uniform speed incremental method regards the winding of each yarn on the warp beam as a process in which the radius increases uniformly with the rotation angle in segments. That is, after each layer of yarn is wound a certain number of times, the radius increases uniformly before entering the next layer of winding. Based on this, the timing of the single radial precession pulse of the pressure roller is determined according to the change in rotation angle, the number of windings in the same layer, and the rate of change of radius between adjacent layers with the angle.

[0081] Preferably, the segmented uniform speed incremental method, also known as the segmented Archimedean spiral incremental method, means that, from the perspective of the average effect of yarn winding, each yarn will have several turns on the same radius during the winding process, and the radius between each number of turns follows the Archimedean spiral equation, including the average cross-sectional area S of a single turn of yarn in the warp beam. min The transverse dimension d of a single yarn on a warp beam with a winding density of ρ can be calculated. Based on the axial length a of the warp beam and the total number of yarns N, the number of loops n of the same layer and radius can be obtained. r ,

[0082] n r = a / (N*d)

[0083] The rate of change of the segment radius with respect to the angle

[0084] Δr θ =(r max -r0) / (2πq max n r )=0.5831N / (2πaρn r N e ) Formula (3)

[0085] When the measured angle θ satisfies the following formula:

[0086]

[0087] The system sends the i-th precession pulse for the pressure roller, causing the radial distance between the pressure roller and the warp axis to increase by Δr. min ;

[0088] Where i = 1, 2, 3, ..., n max n max The maximum number of precession pulses is given by mod(θ, 2π), which is the remainder function of θ divided modulo 2π. In this embodiment, n max This refers to the maximum number of continuous Archimedean spiral turns, which is also the actual number of advances of the pressure roller. Considering the number of turns in the same layer, the actual number of yarn turns is generally greater than or equal to n. r *n max .

[0089] Preferably, the method for calculating the transverse dimension d of a single yarn includes the equivalent circle diameter calculation method, which uses a circle to represent the average effect of each turn of a single yarn occupying the axial cross-sectional space along the warp axis after winding.

[0090] d = 2sqrt(S) min / π)

[0091] Here, sqrt() is the square root operation; this equivalent method is based on the fact that the solid cross-section of the wound yarn is closer to a circle.

[0092] Example 3

[0093] The difference from Example 2 is that the method for calculating the transverse dimension d of a single yarn includes an equivalent square calculation method, which uses a square to represent the average effect of each turn of a single yarn occupying the axial cross-sectional space along the warp axis after winding.

[0094] d = sqrt(S min )

[0095] This equivalent method is based on the fact that the wound yarn fills the winding space of the warp beam, while the circular equivalent method has gaps between adjacent circles.

[0096] Example 4

[0097] The difference from Example 1 is that, preferably, the initial distance between the warp beam and the surface of the pressure roller is greater than or equal to the radial dimension L of the single yarn and less than or equal to 5Δr. min When the yarn begins to wind, a certain space needs to be reserved between the warp beam and the pressure roller to facilitate the initial winding. However, it is difficult to precisely control this distance as Δr. min When the reserved space is less than Δr min The initial winding density may be greater than the set value ρ, and the reserved space may be greater than Δr. min The initial winding density may be less than the set value ρ. Whether it is large or small, although the initial winding density may not be ideal, as long as it is not too large or too small, it is within the allowable error range and has little impact on the winding density of the entire warp beam.

[0098] Preferably, the radial dimension of the single yarn L = 2sqrt(S) min / π), which is consistent with the calculation method of the transverse dimension d of the single yarn, that is, the diameter obtained by the equivalent circle calculation method, or L is the diameter of the unwound bare yarn. In this embodiment, the bare yarn diameter is used.

[0099] In this embodiment, the initial distance between the warp beam and the surface of the pressure roller is 2L. In fact, since the yarn itself is elastic, this distance may not be preset in Embodiment 1.

[0100] Example 5

[0101] The difference from Example 4 is that the radial dimension of the single yarn L = sqrt(S) min The method for calculating the transverse dimension d of a single yarn is consistent with that for calculating the diameter using the equivalent square method.

[0102] Example 6

[0103] The difference from Example 1 is that, preferably, after the warp yarn is fully wound, the pressure roller remains in its final position and the warp continues to rotate for no less than a specified number of turns to ensure that the outer layer yarn is shaped and the density is constant at a predetermined value ρ. In this example, the specified number of turns is 10 turns.

[0104] Without considering the deformation caused by the release of internal stress after winding, which would affect the density, the winding is stopped once the yarn is fully wound. Example 1 adopted this method, and the actual impact is not significant because even if stress exists, it is small and mainly located on the outer ring, so the impact is minimal. However, using this example, the warp beam rotates 10 more times without producing significant extra losses, and the overall quality is more controllable, which is worthwhile.

[0105] Example 7

[0106] The difference from Examples 1 and 2 is that the initial distance between the warp beam and the surface of the pressing roller in this example is Δr. min The first pulse precession is implemented first, leaving space for the yarn to begin winding. Theoretically, the winding density of the reserved space is ρ. The control method includes the following steps:

[0107] S1. Set the initial winding distance between the pressure roller and the empty warp beam;

[0108] S2, yarn winding, measuring the cumulative rotation angle of the warp beam;

[0109] S3. Condition judgment: After the winding starts, the pressure roller is moved radially based on whether the warp beam rotation angle meets the condition for issuing the advance pulse. The condition judgment includes the condition judgment of formula (1) by the uniform speed increment method or the condition judgment of formula (4) by the segmented uniform speed increment method.

[0110] S4. Warp yarn roll setting: After the yarn is wound, the pressure roller maintains the distance from the warp beam, and the warp beam rotates continuously for no less than a specified number of turns, so that the yarn roll is set under continuous constant pressure.

[0111] It should be noted that the warp beam winding angle corresponding to each pulse control command issued by the system is not fixed; only the minimum radial movement distance Δr of the pressure roller is fixed. min .

[0112] The basic principle of this invention is as follows: The yarn winding density control method for a loose warping machine designed in this invention does not determine and control the yarn winding density of the warp beam by directly measuring the displacement or pressure of the pressure roller on the yarn. Instead, it is achieved by measuring the rotation angle of the warp beam and rationally controlling the pressure roller according to the minimum radial precession of a single pulse. This is because both displacement and pressure measurements can lead to uneven control due to measurement errors, resulting in significant fluctuations in yarn density. However, calculating and controlling the displacement by the warp beam rotation angle produces very small errors. Even the minimum displacement corresponding to a single precession pulse requires several rotations of the warp beam to reach, and angle measurement with accuracy at the minute and second level is easily achievable. Therefore, measuring and controlling the pressure roller displacement by rotating the angle can achieve high precision, resulting in high accuracy in controlling the constant yarn winding density of the warp beam, and making density adjustment more convenient. The control, judgment, and adjustment functions are all automatically implemented through a program, making system design and application more convenient.

[0113] The above description is only a part of the more systematic and comprehensive embodiments of the loose warping machine yarn winding density control method of the present invention. In fact, there are many equivalent calculation methods for various parameters, and there are also many combinations of them. For example, Embodiment 5 can be arbitrarily combined with Embodiments 3 and 4, and Embodiment 4 can also be combined with Embodiment 2 for optimization design, etc. These combinations or preferred solutions should also be considered as the protection scope of the present invention, and will not be listed one by one here.

Claims

1. A method for controlling yarn winding density in a loose warping machine, characterized in that, The radial movement of the pressure roller is controlled based on the cumulative rotation angle of the warp beam, and the radial movement of the pressure roller is controlled in units of the minimum drive pulse of the radial drive device. The control method includes a uniform speed incremental method or a segmented uniform speed incremental method. The uniform speed increment method treats the winding of each yarn on the warp beam as a process in which the radius increases at a uniform speed with the rotation angle, and determines the timing of the single radial precession pulse of the pressure roller based on the amount of rotation angle change and the radius change rate with the angle. The segmented uniform speed increment method regards the winding of each yarn on the warp beam as a process in which the radius increases uniformly with the rotation angle in segments. That is, after each layer of yarn is wound a certain number of times, the radius increases uniformly before entering the next layer of winding. Based on this, the timing of the single radial advance pulse of the pressure roller is determined according to the change in rotation angle, the number of windings in the same layer, and the rate of change of radius between adjacent layers with the angle. The uniform incremental method includes the following condition as the system issues the i-th pulse for adjustment: Δr = Δr θ *θ = i*Δr min Formula (1) Where Δr is the radius increment, Δr θ Δr is the rate of change of radius with respect to angle, where θ is the cumulative rotation angle of the warp beam around the yarn; min The minimum radial distance of the pressure roller driven by a single drive pulse; i=1,2,3,……,n max n max The maximum number of precession pulses, n max =int((r max -r0) / Δr min ) Where int() is the integer function, the radius of the empty warp beam is r0, and the radius of the fully wound warp beam is r. max ; Yarn count N e The number of synchronously wound yarns is N, the axial length of the warp beam is a, the set density is ρ, and the total number of turns of a single yarn after it is fully wound is q. max Then we have: Δr θ =(r max -r0) / (2πq max )= 0.5831N / (2πrN e ) formula (2).

2. The method for controlling yarn winding density of a loose warping machine according to claim 1, characterized in that, The segmented uniform velocity incremental method includes using the average cross-sectional area S of a single loop of yarn in the warp beam. min The transverse dimension d of a single yarn on a warp beam with a winding density of ρ can be calculated. Based on the axial length a of the warp beam and the total number of yarns N, the number of loops n of the same layer and radius can be obtained. r , n r =a / (N*d) The rate of change of the segment radius with respect to the angle Δr θ =(r max -r0) / (2πq max n r )= 0.5831N / (2πaρn r N e ) Equation (3) When the measured angle θ satisfies the following formula: Formula (4) The system sends the i-th precession pulse for the pressure roller, causing the radial distance between the pressure roller and the warp axis to increase by Δr. min ; Where i = 1, 2, 3, ..., n max n max The maximum number of precession pulses, Let θ be the remainder function when divided modulo 2π.

3. The method for controlling yarn winding density of a loose warping machine according to claim 2, characterized in that, The method for calculating the transverse dimension d of a single yarn includes the equivalent circle diameter calculation method, which uses a circle to represent the average effect of each turn of a single yarn occupying the cross-sectional space after winding. d=2sqrt(S min / π) Here, sqrt() performs the square root operation.

4. The method for controlling yarn winding density of a loose warping machine according to claim 2, characterized in that, The method for calculating the transverse dimension d of a single yarn includes an equivalent square calculation method, which uses a square to represent the average effect of each turn of a single yarn occupying the cross-sectional space after winding. d=sqrt(S min )。 5. A method for controlling yarn winding density on a loose warping machine according to any one of claims 1 to 4, characterized in that, The initial distance between the warp beam and the pressure roller surface is greater than or equal to the radial dimension L of the single yarn and less than or equal to 5Δr. min .

6. The method for controlling yarn winding density of a loose warping machine according to claim 5, characterized in that, The radial dimension of the single yarn is L = 2sqrt(S min / π) or the diameter of the unwound bare wire.

7. The method for controlling yarn winding density of a loose warping machine according to claim 5, characterized in that, The radial dimension of the single yarn is L = sqrt(S min ).

8. The method for controlling yarn winding density of a loose warping machine according to claim 5, characterized in that, After the warp beam is fully wound with yarn, the pressure roller remains in its final position while the warp beam continues to rotate for at least the specified number of turns.

9. A method for controlling yarn winding density on a loose warping machine according to any one of claims 1 to 4, characterized in that, The initial distance between the warp beam and the surface of the pressing roller is Δr min The control method includes the following steps: S1. Set the initial winding distance between the pressure roller and the empty warp beam; S2, yarn winding, measuring the cumulative rotation angle of the warp beam; S3. Condition judgment: After the winding starts, the pressure roller is moved radially depending on whether the rotation angle of the warp beam meets the condition for issuing the advance pulse. S4. Warp yarn roll setting: After the yarn is wound, the pressure roller maintains the distance from the warp beam, and the warp beam rotates continuously for no less than a specified number of turns, so that the yarn roll is set under continuous constant pressure.

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