A method for controlling the weft yarn transfer of a rapier loom

Abstract

The application provides a method for controlling weft yarn transfer of a rapier weft insertion, belonging to the technical field of textile machinery, and representing time component by main shaft rotation angle, establishing a variable speed weft insertion parameter model of a weft feeding rapier and a weft receiving rapier based on Fourier series, satisfying weft insertion motion characteristics and process requirements, and then obtaining final variable speed weft insertion displacement S(x), weft insertion speed S'(x) and acceleration S''(x) equations through processing. The application analyzes weft yarn motion law from the perspective of weft insertion process, designs variable speed motion law based on Fourier series, converts process conditions into model boundary conditions, establishes a parameterized variable speed weft insertion model, realizes model satisfaction to the process, and provides a theoretical reference for weft insertion parameterized design.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of textile machinery, and particularly relates to a method for controlling weft yarn transfer of a rapier. BACKGROUND

[0002] The rapier loom is the most widely used shuttleless loom, which has the characteristics of high speed, high automation degree and high efficiency in production, and the active weft insertion mode of the rapier loom has strong adaptability to various yarns.

[0003] At present, the rapier motion is usually controlled by a spatial four-bar linkage mechanism, a variable lead screw mechanism and a conjugate cam mechanism, so that the rapier motion characteristics are affected by the linkage size and the cam profile shape. However, the relationship between the rapier driving mechanism parameters and the rapier motion characteristics is not clear, and the vibration control of the machine is not ideal when the rapier is running at high speed, especially when the loom width is large, the rapier vibration is serious, and the normal transfer of the rapier cannot be realized. Meanwhile, when the loom width is adjusted, it needs to be adjusted repeatedly several times to meet the weaving process requirements. SUMMARY

[0004] The present application aims to provide a method for controlling weft yarn transfer of a rapier, which is mainly used for the control of the motion of rigid and flexible rapiers and the transfer of weft yarns.

[0005] To solve the above technical problems, the technical scheme adopted by the present application is as follows: a method for controlling weft yarn transfer of a rapier, comprising the following steps:

[0006] S1, based on Fourier series, a variable speed weft insertion parameter model of a weft feeding rapier and a weft receiving rapier is established:

[0007] Any state curve is simulated by Fourier series expansion, and the series expansion of the curve is,

[0008]

[0009] In formula (1), k i (1) is the first series coefficient; k i (2) is the second series coefficient; w is the series fundamental frequency; t is time; Q(t) is a function of time t; i is a quantity, i=1, 2, 3, …, n, and the derivative of formula (1) with respect to t is obtained Q(t) speed,

[0010] The weft insertion speed starts from zero and ends at zero, and the speed condition can be met by removing the sine term in the series. The number of series is limited by the process boundary, and n boundaries can only determine n-1 series (the process boundary refers to the displacement, speed and acceleration values of the motion law of the rapier corresponding to the displacement of the main shaft of the loom when it rotates through a certain angle). The formula (1) needs to be reduced to a finite term, and the time component is represented by the main shaft rotation angle. The unified displacement equation that meets the weft insertion motion characteristics and the process is established based on the Fourier series,

[0011]

[0012] In formula (2), Q(θ) is the displacement of the rapier corresponding to the main shaft rotation angle θ, θ is the main shaft rotation angle; θ max is the main shaft rotation angle corresponding to the maximum stroke of the rapier head.

[0013] The motion law of the weft insertion rapier and the weft receiving rapier that realizes the weft transfer is expressed by the displacement equation model of formula (2). When the rapier represents the weft insertion rapier, the rapier head represents the weft insertion rapier head. When the rapier represents the weft receiving rapier, the rapier head represents the weft receiving rapier head.

[0014] S2, in the process of symmetrical weft insertion, θ max is 180°, at which time the weft insertion time is consistent with the weft withdrawal time.

[0015] S3, in the process of asymmetrical weft insertion, the weft insertion rapier and the weft receiving rapier are not moved at the same time, and there is a certain offset between the cycle start points, so that the weft transfer position is offset. This influence is represented by introducing the transfer offset coefficient e0 into the displacement equation. When the weft insertion time is asymmetric with the weft withdrawal time, the weft insertion time proportion coefficient (or stroke offset coefficient) e1 is introduced into the displacement equation. The displacement of formula (2) is normalized to obtain the final variable-speed weft insertion displacement equation,

[0016]

[0017] In formula (3), S(x) is the final variable-speed weft insertion displacement; S is the rapier head displacement; x is the normalized parameter of the main shaft of the loom, and x=θ / 360°; the stroke offset coefficient e1=θ max / 180° represents the scaling of the weft insertion time and the weft withdrawal time; the transfer offset coefficient e0 represents the size of the weft transfer offset distance; S max is the maximum stroke of the weft insertion, which is related to the fabric width B, the transfer stroke W D , and the width stroke W S . max D S

[0018] S4, the main shaft rotation angle θ and the time t, the rotation frequency w​​​r Regarding, there is θ = w r t relationship, the derivative of formula (2) with respect to time t can obtain the weft leading speed S'(x) and acceleration S''(x) as,

[0019]

[0020]

[0021] S5, the process boundary is converted into a standard form and substituted into formula (3) (4) (5), while the e0, e1 value is given, the Fourier series coefficient can be obtained by the undetermined coefficient method.

[0022] Due to the adoption of the above technical scheme, the present application has the following beneficial effects:

[0023] (1) The present application establishes a rapier motion control model based on Fourier series, which can meet the process requirements of space four-bar linkage, variable lead screw and conjugate cam mechanism weft leading, and the parameter adjustment is convenient.

[0024] (2) The present application establishes a weft feeding rapier and a weft receiving rapier motion model based on the weft leading process requirements, and can meet the requirements of different weft leading processes by introducing a bias coefficient, and has a wide range of applications.

[0025] (3) The present application can independently design parameters such as negative acceleration peak value and initial acceleration peak value according to the change of weft leading speed and width, control the maximum speed of weft leading and the relative speed and inertial force at the time of weft yarn transfer, and control the stable transfer of weft yarn.

[0026] (4) The present application can accurately control the motion starting time of the weft receiving rapier and the weft feeding rapier by adjusting the bias coefficient, meet the requirements of weft transfer time, transfer stroke and out-of-width stroke and other process parameters, and one adjustment can meet the process requirements.

[0027] (5) With the application of electronic cam technology in looms, this technology can be extended to electronic cam control technology, meet the process requirements of electronic weft leading and beating-up, and the adjustment parameters are convenient and simple, and the motion control is stable.

[0028] The weft leading process of the loom is complex, different types of fabrics often use different processes, so a parameterized weft leading model considering different processes is extremely important. The present application is directed to a rapier loom, analyzes the weft yarn motion law from the weft leading process perspective, designs a variable speed motion law based on Fourier series, converts the process conditions into model boundary conditions, establishes a parameterized variable speed weft leading model, and realizes the satisfaction of the model to the process, providing a theoretical reference for weft leading parameterization design. BRIEF DESCRIPTION OF DRAWINGS

[0029] The advantages and implementations of the present application will be more obvious by referring to the drawings and examples, and the drawings shown in the drawings are only used to explain the present application, and do not constitute any sense of limitation to the present application, and in the drawings:

[0030] Figure 1 is a schematic diagram of the double-sided weft insertion motion of the present application.

[0031] Figure 2 is a schematic diagram of the time distribution of three motions of the loom of the present application.

[0032] Figure 3 is a schematic diagram of the time distribution of the weft insertion process of the present application.

[0033] Figure 4 is a comparison diagram of the actual measurement and the model on the weft insertion law and the process influence of the present application.

[0034] Figure 5 is a comparison diagram of the different acceleration boundary a0, a1 on the weft insertion law and the process influence of the present application.

[0035] Figure 6 is a comparison diagram of the different θ sL (θ sR ) on the weft insertion law and the process influence of the present application.

[0036] Figure 7 is a comparison diagram of the different e1 on the weft insertion law and the process influence of the present application.

[0037] Figure 8 is a comparison diagram of the different e0 on the weft insertion law and the process influence of the present application.

[0038] in the figure:

[0039] 1, weft feeding sword; 2, weft receiving sword;

[0040] I, reed; II, weft feeding guide rail; III, weft releasing device; IV, color selector; V, dust collector; VI, weft accumulator; VII, scissors; VIII, warp; IX, fabric; X, weft; XI, weft receiving guide rail. DETAILED DESCRIPTION

[0041] For the rapier loom, the weft motion law is analyzed from the weft insertion process, the variable speed motion law is designed based on the Fourier series, the process conditions are converted into model boundary conditions, the parameterized variable speed weft insertion model is established, the model is satisfied with the process, and a theoretical reference is provided for the parameterized design of weft insertion.

[0042] Weft insertion process analysis:

[0043] Rapier weft insertion is mainly divided into single-sided and double-sided weft insertion. Single-sided weft insertion only has a weft insertion sword 1, which pulls the weft yarn from one side to the other side, so the single-sided weft insertion process and movement design are simple, but it is only suitable for small-width fabrics and low-speed looms. In view of the shortcomings of single-sided weft insertion, the weft insertion form has developed into a double-sided form, and the weft insertion sword 1 and the weft receiving sword 2 are responsible for weft insertion and weft receiving respectively, and they move towards each other during weft insertion, so their movement speed is only half of that of the single-sided form, and it is more suitable for wide-width, high-speed and other occasions.

[0044] As shown in Figure 1 The existing double-sided weft insertion loom includes a weft insertion guide rail II, a reed I and a weft receiving guide rail XI arranged in sequence from left to right, the weft insertion guide rail II is provided with a weft insertion sword 1, the weft receiving guide rail XI is provided with a weft receiving sword 2, a dust collector V is installed on the side of the weft insertion guide rail II, and a weft releasing device III is installed on the side of the weft receiving guide rail XI. The weft yarn X transmitted by the weft insertion sword 1 is transmitted to the sword head by the weft storage device VI through the color selector IV. The weft yarn X and the warp yarn VIII jointly form the fabric IX.

[0045] During the double-sided weft insertion movement, the sword head continuously moves towards each other during the weaving cycle to complete the weft insertion work, and each sword head cyclically moves in and out of the sword. If the starting time point of the weft insertion sword 1 movement is defined as the cycle starting point, the movement is mainly divided into weft insertion and weft receiving parts.

[0046] (1) Weft insertion: the weft insertion sword 1 starts to move right along the guide rail II at the T1 position; when it moves to the T2 position, the sword head clamps the weft yarn and continues to move together, and the weft yarn starts to move instantaneously, so the weft yarn system will be subjected to instantaneous impact; continue to move to the T3 position, the sword head starts to enter the shed, by which time the out-of-width distance movement ends and the sword head enters the in-width, and the warp yarn opening remains open. This process point is related to the coordination between the weft insertion and beating-up movements of the loom; then move to the T5 position, which is the maximum distance of the weft insertion sword 1 movement. This position coordinates the weft insertion sword 1 and the weft receiving sword 2 weft yarn transfer, and at the same time, in order to improve the success rate of weft yarn transfer, a relatively small speed needs to be ensured at this time; then the weft insertion sword 1 completes the task and starts to return to the starting position to prepare for the next weft insertion, and passes through the T3, T2 and T1 positions in turn.

[0047] (2) Weft receiving: the weft receiving sword 2 starts to move left from the T7 position, and according to whether it is symmetrical weft insertion, there is a certain offset between the starting time point of its movement and that of the weft insertion sword 1; when the sword head moves to the T6 position, it starts to enter the shed, and the warp yarn opening remains open; then the sword head moves to the T4 position, and the weft yarn transfer is completed; then the sword head starts to return to the T7 position, and when the weft insertion is completed, the scissors VII cut off the excess weft yarn.

[0048] The loom needs coordination and cooperation between each movement to complete weaving, so the time distribution between each movement in the cycle is very important. The weaving movement coordination relationship of the loom with time distribution of the loom main shaft angle (the loom main shaft is the beating shaft, and the loom main shaft angle is the rotation angle of the beating shaft, which rotates at a constant speed) is shown in Figure 2 It can be seen that only when the sword heads are in the width can the shedding, beating and other movements be carried out, so the longer the time occupied by the width, the shorter the time left for beating and other movements, the greater the speed, and the greater the harm such as impact. It is necessary to reasonably allocate. The static stage in the width includes the static (shedding) position and the static (back dead heart) position.

[0049] At the same time, the weft insertion width movement accounts for more than 60% of the entire cycle time, which is extremely important in the entire weaving process. When introducing the process into the parameterized weft insertion model, the process point needs to be converted into model parameters, so the weft insertion can be time-distributed according to the main shaft angle. The weft insertion process time distribution is shown in Figure 3 In the figure, the inner circle is the weft insertion sword 2, and the outer circle is the weft feeding sword 1. The weft feeding sword 1 process position T2 corresponds to the main shaft angle θ k , which is the weft clamping angle, T3 corresponds to θ sL , which is the shedding angle, T5 corresponds to θ zL , which is the maximum displacement angle; the weft insertion sword 2 process position T7 has a certain time offset relative to T1, T1 corresponds to 0° as the starting position, and T6 corresponds to θ sR , which is the shedding angle, T4 corresponds to θ zR , which is the maximum displacement angle.

[0050] The method for controlling the weft transfer of the sword arm weft insertion includes the following steps:

[0051] S1, based on the Fourier series, a variable speed weft insertion parameter model of the weft feeding sword and the weft insertion sword is established:

[0052] The variable speed weft insertion law is essentially a curve that meets certain requirements. In theory, any curve in any state can be simulated by Fourier series expansion. The series expansion of the curve is,

[0053]

[0054] In formula (1), k i (1) is the first series term coefficient; k i (2)is the coefficient of the second order term; w is the fundamental frequency of the series; t is time; Q(t) is a function of time t; i is a number, i = 1, 2, 3, …, n, and the derivative of formula (1) with respect to t is Q(t) velocity. Considering that the weft insertion velocity starts from zero and ends at zero, the velocity condition can be satisfied when the sine term in the series is removed. At the same time, the series is limited by the process boundary, and n boundaries can only determine n-1 order series (the process boundary refers to the displacement, velocity and acceleration values of the motion law of the rapier corresponding to the displacement of the loom main shaft when it rotates through a certain angle, and other process parameters), and formula (1) needs to be reduced to a finite term. The time component is represented by the main shaft rotation angle, and thus the unified displacement equation that satisfies the weft insertion motion characteristics and the process is established based on the Fourier series,

[0055]

[0056] In formula (2), Q(θ) is the displacement of the rapier corresponding to the angle θ of the loom main shaft, θ is the rotation angle of the loom main shaft; θ max is the rotation angle of the main shaft corresponding to the maximum stroke of the rapier head.

[0057] The motion law of the weft insertion rapier 1 and the weft receiving rapier 2 is expressed by the unified displacement equation model of formula (2).

[0058] S2, in the process of symmetrical weft insertion, θ max is 180°, at which time the weft insertion and the weft withdrawal time are consistent

[0059] S3, in the process of asymmetrical weft insertion, the weft insertion rapier 1 and the weft receiving rapier 2 are not moved simultaneously, as Figure 3 shown, there is a certain offset at the start of the cycle, and the weft transfer position is offset, which is represented by introducing the transfer offset coefficient e0 into the displacement equation. For the case where the weft insertion and the weft withdrawal time are asymmetrical, the weft insertion time proportion coefficient (or stroke offset coefficient) e1 is introduced into the displacement equation. The displacement of formula (2) is normalized to obtain the final variable-speed weft insertion displacement equation,

[0060]

[0061] In formula (3), S(x) is the final variable-speed weft insertion displacement; S is the displacement of the rapier head; x is the normalized parameter of the loom main shaft, and x = θ / 360°; the stroke offset coefficient e1 = θ max / 180°, which represents the scaling of the weft insertion and the weft withdrawal time; the transfer offset coefficient e0 represents the size of the weft transfer offset distance; S max is the maximum stroke of the weft insertion, the value of which is related to the fabric width B, the transfer stroke W D , and the width outside stroke W S , and the value is S max = 0.5B + 0.5W D +W S .

[0062] S4, since the main shaft rotation angle θ and time t, rotation frequency w r about, there is θ = w r t relationship, so the formula (2) to time t derivative can be obtained by the weft speed S'(x) and acceleration S"(x) is,

[0063]

[0064]

[0065] S5, the process boundary into the standard form into formula (3) (4) (5), while given e0, e1 value, by the undetermined coefficient method can be obtained Fourier series coefficient.

[0066] Here only show with the weft sword 1 as an example of the main process boundary (the rest of the process boundary can be determined according to the specific needs),

[0067] Displacement boundary:

[0068]

[0069] Acceleration boundary:

[0070]

[0071] Where, s0, s1, a0, a1 are weft parameters, s0 represents the starting displacement parameter, s1 represents the weft displacement parameter, a0 represents the starting acceleration parameter, a1 represents the intersection acceleration parameter.

[0072] In order to verify the speed variable weft parameters model practical and feasibility, RFTL type sword frame loom measured weft rule data as reference, using the speed variable weft parameters model of the invention for rule fitting, its parameters are: e0 = 0, e1 = 1, a0 = 0, a1 =-0.57, s0 = 0, s1 = 1, θ SL (θ SR ) = 63°, B = 2800mm, W D = 30mm, W S = 230mm, ω r = 48.1 rad / s.

[0073] For example, Figure 4As shown in Figure (a), which is a standard displacement comparison diagram, it can be seen that the measured and model values ​​of weft insertion displacement almost coincide, indicating that the model has an excellent effect on the completion of the process position. Figure (b) is a standard velocity comparison diagram, showing a comparison between the measured and model values ​​of velocity, which also have a high degree of overlap, with only a slight deviation near the negative peak value of velocity. As for the acceleration simulation, as shown in Figure (c), the measured values ​​have relatively obvious fluctuations, which are due to measurement errors, while the model values ​​almost have the same curve trend as the measured values, showing a high degree of overlap. Therefore, the variable speed weft insertion parameter model of this invention has good practicality in terms of both process position and motion characteristics, and also verifies the accuracy of this model.

[0074] Analysis of weft insertion model process and motion characteristics

[0075] (1) Influence of process characteristics on acceleration boundary parameters:

[0076] The influence of initial acceleration parameter a0 and transition acceleration parameter a1 on the process:

[0077] like Figure 5 As shown, under the condition of symmetrical weft insertion, its offset coefficients e0 = 0, e1 = 1, and the weft insertion parameter θ SL (θ SR ) = 60°, B = 3200, W D =30, W S Under the conditions of 230, s0 = 0, and s1 = 1, Figures (a) show the standard displacement comparison, (b) show the standard velocity comparison, and (c) show the standard acceleration comparison, illustrating the influence of parameter a0 on the standardized weft displacement, velocity, and acceleration when a1 = -0.54. In Figure (a), the displacement effect primarily influences the initial displacement curve. When a0 = 0, the initial weft insertion displacement curve is the most stable. As a0 increases, the initial curve becomes steeper. Under the same shuttle angle, a smaller a0 results in a smaller out-of-range travel. Therefore, a suitable a0 parameter needs to be selected based on the actual configuration. In Figure (b), the velocity effect results in a larger peak velocity when a0 = 0.4. When a0 = 0.4, the peak velocity is only around 0.5, while when a0 = 0, the peak velocity increases by nearly 40%, which is detrimental to weft insertion stability and increases the system load. The acceleration effect in Figure (c) is similar to the velocity effect, but when a0 is not 0, the initial segment exhibits flexible impact, affecting the service life of the rapier and other components. This should be avoided as much as possible. It is evident that setting the a0 parameter can yield different initial weft insertion characteristics and better starting characteristics, but it will reduce the stability of subsequent weft insertion.

[0078] Meanwhile, Figures (d), (e), and (f) show the standard displacement comparison, standard velocity comparison, and standard acceleration comparison, illustrating the influence of parameter a1 on the standardized weft insertion motion state when a0 = 0. In Figure (d), the displacement effect primarily influences the displacement curve within the 60°–150° (210°–300°) segment of the main axis. When a1 = -0.2, the weft insertion displacement curve in this segment is located at the outermost layer, thus allowing for a greater range of motion under the same shuttle inlet angle, which is beneficial for the configuration of structures such as the color selector. In Figure (e), the velocity effect influences the peak velocity value. Adjusting a1 controls the peak velocity value; both excessively large and excessively small a1 values ​​will cause changes in the peak velocity value. Under these conditions, when a1 is -0.53, the peak velocity is the smallest, and the position of the peak velocity will shift to a certain extent. Regarding the acceleration effect in Figure (f), the a1 parameter mainly affects the acceleration curve of the weft yarn intersection section (around 180°). When a1 = -0.2, this section of the curve is obviously convex upwards, when a1 = -0.9, it is convex downwards, and when a1 = -0.53, this section is the flattest. Combined with the velocity curve, it can be seen that the peak velocity is the smallest at this time, which is beneficial to the stability of weft insertion.

[0079] (2) Influence of process characteristics on the shuttle inlet angle:

[0080] like Figure 6 As shown, when the bias coefficients e0 = 0 and e1 = 1, the weft insertion scissors 1 and 2 have the same motion law. When the weft insertion parameters a0 = 0, a1 = -0.51, B = 3200, W... D =30, W S Under the conditions of θ = 230, s0 = 0, and s1 = 1, Figures (a) show the comparison of standard displacement, (b) show the comparison of standard velocity, and (c) show the comparison of standard acceleration under different θ values. SL (θ SR The standardized weft insertion displacement, velocity, and acceleration response are shown at a certain value. In the displacement graph of Figure (a), a smaller shuttle inlet angle value results in greater curve deformation, when θ... SL (θ SR When θ = 45°, the initial displacement increases rapidly, but becomes extremely slow in the weft insertion section. The displacement change characteristics differ significantly from the other two. This process point severely affects the overall weft insertion pattern and therefore requires careful selection. Furthermore, from the velocity and acceleration graphs in Figures (b) and (c), it can be seen that if θ is too small... SL (θ SR A value of θ will cause a sharp increase in the peak velocity, accompanied by large acceleration fluctuations, and the peak value will also increase significantly. This is because the displacement in the latter half is restricted by the weft yarn intersection position. Similarly, an excessively large θ will also cause this. SL (θ SR A higher θ value will lead to larger peak values ​​for velocity and acceleration, due to the excessively long out-of-amplitude motion time. Therefore, selecting an appropriate θ value within the process range is crucial.SL (θ SR The value of θ can improve the motion performance of the loom and needs to be selected in conjunction with the width factor. SL (θ SR The value of θ directly affects the time allocation for subsequent processes such as weft insertion. SL (θ SR The smaller the θ value, the higher the speed of movements such as weft insertion needs to be, thus increasing the load on the mechanical system and compromising the stability of the mechanism. It can be seen that in θ... SL (θ SR A value of θ = 60° is most suitable, as the motion is most stable at this angle, and the peak velocity is only θ. SL (θ SR It is about 68% of the maximum peak value when ) = 45°.

[0081] (3) Influence of process characteristics on the stroke offset coefficient e1:

[0082] When the weft insertion is asymmetrical, its coefficient mainly affects the distribution relationship between the advance and retreat of the rapier, thus it can adjust the motion characteristics during the advance and retreat of the rapier and meet the weaving process design of looms with special needs.

[0083] like Figure 7 As shown, with the crossover bias coefficient e0 = 0 and the weft insertion parameters a0 = 0, a1 = -0.51, θ SL (θ SR ) = 60°, B = 3200, W D =30, W S When s = 230, s0 = 0, and s1 = 1, Figure 7 (a) Standard displacement comparison diagram Figure 7 (b) Standard speed comparison chart Figure 7 (c) The standard acceleration comparison chart shows the standardized weft displacement, velocity, and acceleration response under different e1 values. Figure 7 As can be seen from the displacement graph in (a), the peak position of the displacement curve shifts significantly under different e1 values. When e1 is close to 1, the peak position is close to the halfway point of the weft insertion cycle. The larger e1 is, the further the peak position is from the second half of the cycle, thus delaying the weft yarn handover time. This is beneficial for the stability of weft insertion in the first half of the cycle, but the overall cycle time remains unchanged. It is only the time distribution of the advance and retreat of the spar that changes, which has a detrimental effect on the second half of the cycle. Figure 7 (b) The velocity graph shows that different e1 values ​​can change the peak velocity and its position. When e1 = 1.40, the peak velocity in the first half is about 0.4, while the peak velocity in the second half reaches about 0.9. Compared with e1 = 1.07, the first half decreases by 27%, but the second half increases by 63%. Therefore, the decrease in velocity is not as large as the increase, and the overall motion characteristics deteriorate. However, if the time proportion is reasonably allocated in combination with the factors affecting vibration characteristics, it will have a certain vibration control effect.Figure 8 (c) The acceleration image of (c) shows that the value of e1 increases, the acceleration at the point of intersection with the weft yarn increases, and the impact of flexibility increases, which is not conducive to smooth intersection and affects the stability of the loom. Therefore, it is generally used in situations that need to meet special process requirements.

[0084] (4) Process characteristics of intersection bias coefficient e0:

[0085] The intersection bias coefficient e0 mainly represents the translation of the weft insertion period, so the weft insertion speed and acceleration characteristics do not change much. Its main purpose is to obtain a smaller relative speed of the weft yarn at the intersection, which can improve the success rate of intersection.

[0086] As shown in Figure 8 , Figure 8 (a) e0 = 0, Figure 8 (b) e0 = 0.65, Figure 8 (c) e0 = 0.9, Figure 8 (d) e0 = 0.51 show the motion curve of the weft insertion sword under the condition of a0 = 0, a1 = -0.51, θ SL (θ SR ) = 60°, B = 3200, W D = 30, W S = 230, s0 = 0, s1 = 1, where the upper curve represents the weft insertion sword, and the lower curve represents the weft insertion sword. Figure 8 (a) shows that during the weft yarn intersection process, the weft insertion sword 1 and the weft insertion sword 2 reach the center of the shed at the same time, and then retreat. The first half is in the sword insertion stage of the weft insertion sword 1 and the weft insertion sword 2, and the weft yarn is controlled by the weft insertion sword 1 to be tensioned. The second half is in the sword withdrawal stage of the weft insertion sword 1 and the weft insertion sword 2. Due to the retreat of the weft insertion sword 1, the weft yarn is relaxed before being completely transferred to the weft insertion sword 2, which affects the weft yarn intersection. Moreover, the motion directions of the two swords are opposite at any time, and the relative motion speed is large, thereby increasing the impact of the sword head on the weft yarn. Such intersection conditions can complete the weft yarn intersection, but are not ideal. Figure 8 (b) shows that the weft yarn intersection process is always in the sword insertion stage of the weft insertion sword 1 and the sword withdrawal stage of the weft insertion sword 2, and the motion directions of the two swords are the same at any time. This tracking intersection makes the relative motion speed of the two swords small, and the impact tension of the weft yarn intersection is small. At the same time, since the weft insertion sword 1 continues to insert the sword, the weft yarn is controlled by the weft insertion sword 1 to be tensioned before being completely transferred to the weft insertion sword 2. This is an ideal intersection condition and is widely used in the new generation of sword looms. Figure 8(c) The movement relationship of the weft insertion sword 1 and the weft receiving sword 2 during the weft transfer is relatively complex. The weft insertion sword 1 and the weft receiving sword 2 are both in the advancing sword state when they start to meet. When the weft receiving sword 2 is fully advanced, the weft insertion sword 1 is still in the advancing sword state until it is fully advanced. Then the weft insertion sword 1 and the weft receiving sword 2 are both in the retreating sword state until they are fully withdrawn from the shed. ​ (d) The weft insertion sword 1 and the weft receiving sword 2 are both in the advancing sword state when they start to meet. The weft insertion sword 1 is fully advanced earlier than the weft receiving sword 2. When the weft insertion sword 1 starts to retreat, the weft receiving sword 2 is still in the advancing sword state. The weft transfer occurs when the weft receiving sword 2 retreats.

[0087] The above detailed description of the embodiments of the present application is only a preferred embodiment of the present application and should not be considered as limiting the scope of the present application. Any equivalent changes and improvements made within the scope of the present application should still be considered as falling within the scope of the present patent.

Claims

1. A method for controlling the weft yarn intersection of a rapier insertion shaft, characterized in that: Includes the following steps: S1. Based on Fourier series, establish a variable-speed weft insertion parameter model for the weft feeder and the weft receiver: The curve under any condition is simulated using Fourier series expansion. The series expansion of the curve is as follows: （1） In equation (1), k i (1) The coefficients of the first-order terms; k i (2) The coefficient of the second-order numerical term; w The fundamental frequency of the series; t For time; Q ( t (Regarding time) t The function; i Let i be the number of elements, i = 1, 2, 3, ..., n; Apply equation (1) to t Differentiation yields Q ( t Latitude speed; The weft insertion speed starts from zero and ends at zero. To satisfy the speed condition, the sine term in the series needs to be removed. At the same time, the series is determined by the process boundary, reducing equation (1) to a finite number of terms. The time component is represented by the principal axis rotation angle. Based on the Fourier series, a unified displacement equation satisfying the weft insertion motion characteristics and the process is established as follows: （2） In equation (2), The angle through which the loom spindle rotates θ The corresponding spar displacement at that time. θ This refers to the spindle rotation angle of the loom. θ max The principal axis rotation angle corresponding to the maximum stroke of the sword tip; S2. During the process of symmetrical weft insertion. θ max Take a 180° angle, and ensure the time for advancing and retreating the sword is the same; S3. During asymmetrical weft insertion, the feed dart and the receive dart do not move simultaneously; their starting points for the cycle are offset, causing a shift in the weft yarn intersection position. This offset affects the intersection offset coefficient. e 0 introduces equation (2) to indicate that when the advance and retreat times of the sword are asymmetrical, the stroke offset coefficient is used to adjust the stroke offset coefficient. e 1. The introduction of equation (2) indicates; After normalizing equation (2), the final variable speed weft displacement equation is obtained as follows: （3） In equation (3), This is the final variable speed weft insertion displacement; S This refers to the displacement of the sword tip; x Standardized parameters for the loom spindle, and x = θ / 360°; travel offset coefficient e 1= θ max / 180° indicates scaling of the sword advance and retreat times; handover offset coefficient. e 0 indicates the magnitude of the weft yarn overlap offset distance; S max This is the maximum weft insertion distance, and its value is related to the fabric width. B handover stroke W D , Amplitude of movement W S related, S max =0.5 B +0.5 W D + W S ; S4, Spindle rotation angle θ With time t Frequency conversion w r Related, Existing θ = w r t The relationship is that equation (3) is related to time. t Differentiation yields the latitude velocity. and acceleration for, （4） （5） S5. Transform the process boundary into a standard form and substitute it into equations (3), (4), and (5), while giving... e 0、 e The coefficients of the Fourier series can be obtained by using the method of undetermined coefficients. The process boundary refers to the displacement, velocity, and acceleration values ​​of the rapier motion law corresponding to the main shaft of the loom rotating through a certain angle.

2. The method for controlling the weft yarn intersection of the rapier insertion according to claim 1, characterized in that: The motion laws of the weft-feeding sword and the weft-receiving sword that realize the weft insertion and weft yarn exchange are both expressed by the displacement equation model of equation (2). When the sword rod represents the weft-feeding sword rod, the sword head represents the weft-feeding sword head; when the sword rod represents the weft-receiving sword rod, the sword head represents the weft-receiving sword head.

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