Weaving control method based on special-shaped core mold

Abstract

The present invention relates to the technical field of composite material weaving, and in particular to a weaving control method based on a special-shaped structure core mold, which comprises the following steps: discretizing the special-shaped structure core mold into multiple equivalent core molds; setting the expected weaving speed, expected convergence length and expected weaving length of the equivalent core mold in the current weaving stage; advancing the equivalent core mold, and adjusting the pulling speed of the equivalent core mold so that the weaving speed of the weaving machine approaches the expected weaving speed; adjusting the advancing distance of the equivalent core mold by the expected weaving length so that the braided fabric on the equivalent core mold reaches the expected weaving length. The present invention not only realizes the automatic adjustment of the braiding angle by controlling the advancing distance of the braided special-shaped structure core mold, making the braiding angle more stable and the overall braiding angle error smaller, but also solves the problem of unstable braiding angle caused by continuous change of the radius of the special-shaped structure core mold in the weaving process of the special-shaped structure core mold preform.

Description

Technical Field

[0001] The invention relates to the technical field of composite material weaving, in particular to a weaving control method based on a special-shaped structure core mold. Background Art

[0002] With the continuous promotion of cutting-edge technologies such as aerospace, composite material preparation and molding technology has become increasingly mature. Weaving technology has been widely used to prepare various three-dimensional textile preforms for composite materials because of its simplicity, stability, high degree of automation and near net shape. Composite material woven preforms can obtain complex parts with lighter weight without any connection or cutting. This complex part can not only withstand different loads, but also has a higher damage tolerance, so it is more stable and reliable. In the weaving process of composite materials, the preform is formed by the cross-entanglement of clockwise and counterclockwise moving yarns. Among them, the braiding angle is the angle formed by the yarn and the axis of the core mold, so the braiding angle has a great influence on the mechanical properties of the finished composite material. At present, in the weaving process of pulling the special-shaped structure core mold by the robot arm of the braider, realizing the precise control of the pulling speed and then stabilizing the braiding angle has become one of the key problems that need to be solved urgently. There is an urgent need for a control braiding control method that can obtain a stable braiding angle by regulating the pulling speed. Summary of the invention

[0003] In response to the needs of actual engineering projects, in the first aspect, the present invention provides a weaving control method based on a special-shaped structural core mold, comprising the following steps: discretizing the special-shaped structural core mold into multiple equivalent core molds; setting the expected weaving speed, expected convergence length and expected weaving length of the equivalent core mold in the current weaving stage; advancing the equivalent core mold, and adjusting the traction speed of the equivalent core mold so that the weaving speed of the weaving machine approaches the expected weaving speed; adjusting the advancement distance of the equivalent core mold according to the expected weaving length so that the braided fabric on the equivalent core mold reaches the expected weaving length. The weaving control method based on the special-shaped structure core mold proposed in the present invention controls the weaving process of the braided fabric on each equivalent core mold obtained after discretization by respectively adjusting the traction speed in the unstable weaving stage and the advancement distance in the stable weaving stage. It not only controls the advancement distance of the weaving special-shaped structure core mold to make the weaving length on the core mold reach the expected length, but also realizes automatic adjustment of the braiding angle, so that the braiding angle is more stable and the overall braiding angle error is smaller, which solves the problem of unstable braiding angle caused by continuous change of the radius of the special-shaped structure core mold in the weaving process of the special-shaped structure core mold preform. At the same time, the weaving control method of the present invention is of great significance for innovating the weaving technology of the variable-section arbitrary curvature core mold.

[0004] Optionally, the discretization of the special-shaped structure core mold into multiple equivalent core molds includes the following steps: discretizing the special-shaped structure core mold into multiple cylinders of equal length according to the morphological characteristics of the special-shaped structure core mold; approximately equivalent the cylinder to a cylinder, and using the cylinder to obtain an equivalent core mold, the approximate radius r of the cylinder i Satisfies the following formula:

[0005]

[0006] Where i = 1, 2, ..., n, i represents the discrete point number on the center axis of the special-shaped core mold, r O(i-1) Indicates the cross-sectional radius corresponding to the discrete point number i-1, r O(i) Indicates the cross-sectional radius corresponding to the discrete point number i.

[0007] Optionally, advancing the equivalent core mold and adjusting the traction speed of the equivalent core mold so that the weaving speed of the braiding machine approaches the expected weaving speed includes the following steps: setting a first advancing distance and advancing the equivalent core mold according to the first advancing distance; decomposing the traction speed of the equivalent core mold at the weaving point to obtain the weaving speed of the braiding machine and the weaving point moving speed; obtaining, through the weaving speed, a functional relationship between the weaving speed and time when the approximate radius of the equivalent core mold changes suddenly; and using the functional relationship between the weaving speed and time, adjusting the traction speed so that the weaving speed approaches the expected weaving speed.

[0008] Optionally, the functional relationship of the braiding speed changing with time satisfies the following formula:

[0009]

[0010] Among them, V b represents the weaving speed, V represents the pulling speed, r i represents the approximate radius of the ith equivalent core mold, ω represents the braiding circumferential speed of the braiding machine, h0(i) represents the initial convergence length of the ith equivalent core mold, and R represents the guide wheel radius of the braiding machine.

[0011] Optionally, the method of obtaining the functional relationship of the weaving speed over time when the approximate radius of the equivalent core mold suddenly changes through the weaving speed includes the following steps: obtaining the differential relationship of the convergence length over time when the approximate radius of the equivalent core mold suddenly changes; obtaining a first-order linear differential equation of the convergence length over time through the differential relationship; setting the initial conditions of the first-order linear differential equation; solving the first-order linear differential equation using the initial conditions to obtain the functional relationship of the convergence length over time; and obtaining the functional relationship of the weaving speed over time using the functional relationship of the convergence length over time.

[0012] Optionally, the functional relationship of the convergence length changing with time satisfies the following formula:

[0013]

[0014] Among them, h i (t) represents the time-varying convergence length, h0(i) represents the initial convergence length of the equivalent core mode of the i-th segment, V represents the pulling speed, r i represents the approximate radius of the equivalent core mold of the i-th section, ω represents the braiding circumferential speed of the braiding machine, and R represents the guide wheel radius of the braiding machine.

[0015] Optionally, adjusting the advancement distance of the equivalent core mold by the expected braiding length so that the braided fabric on the equivalent core mold reaches the expected braiding length comprises the following steps: obtaining the braiding length within a first advancement distance by utilizing the functional relationship between the braiding speed and time; obtaining a second advancement distance by combining the braiding length with the expected braiding length; and advancing the equivalent core mold according to the second advancement distance so that the braided fabric on the equivalent core mold reaches the expected braiding length.

[0016] Optionally, the method of obtaining the braiding length of the braiding machine within the first advancement distance by utilizing the functional relationship between the braiding speed and time comprises the following steps: obtaining the time length consumed by the braiding machine in the process of advancing the first advancement distance; utilizing the time length in combination with the expected braiding speed to obtain the traction speed of the braiding machine within the first advancement distance; and obtaining the braiding length of the braiding machine within the first advancement distance by combining the traction speed, time length and the braiding speed with time.

[0017] Optionally, the braiding length satisfies the following formula:

[0018]

[0019] Among them, l i represents the braiding length of the i-th equivalent core mold braided by the braiding machine within the first advancement distance, t i represents the time length consumed by the braiding machine in advancing the first advancing distance, d1 represents the first advancing distance, h0(i) represents the initial convergence length of the i-th equivalent core mode, V represents the traction speed, r i represents the approximate radius of the equivalent core mold of the i-th section, ω represents the braiding circumferential speed of the braiding machine, and R represents the guide wheel radius of the braiding machine.

[0020] Optionally, the second advancing distance satisfies the following formula:

[0021] d2=Ll i ,

[0022] Where d2 represents the second advancement distance, L represents the desired braiding length, and l i It represents the braiding length of the i-th section equivalent core mold braided by the braiding machine within the first advancement distance.

[0023] In the second aspect, the present invention further provides a weaving control system based on a special-shaped structure core mold, and the weaving control system based on the special-shaped structure core mold is applicable to the weaving control method based on the special-shaped structure core mold described in the first aspect, including: a core mold discrete module, the core mold discrete module is used to discretize the special-shaped structure core mold into multiple segments of equivalent core molds; a data setting module, the data setting module is used to set the expected weaving speed, expected convergence length and expected weaving length of the equivalent core mold in the current weaving stage; a first adjustment module, the initial adjustment module is used to advance the equivalent core mold and adjust the traction speed of the equivalent core mold so that the weaving speed of the weaving machine approaches the expected weaving speed; a second adjustment module, the second adjustment module is used to adjust the advancement distance of the equivalent core mold according to the expected weaving length, so that the braided fabric on the equivalent core mold reaches the expected weaving length; a weaving cycle module, the weaving cycle module is used to control the weaving cycle process according to the discrete result of the core mold discrete module. The weaving control system based on the special-shaped structure core mold works together through multiple modules to stably implement the weaving control method based on the special-shaped structure core mold, that is, to achieve stable control of the weaving angle by adjusting the traction speed in real time. At the same time, the system has a compact structure, stable operation, and is easy to install, which improves the practical applicability of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a flow chart of the weaving control method based on the special-shaped structure core mold of the present invention;

[0025] Figure 2 It is a schematic diagram of discretization of the special-shaped structure core mold of the present invention;

[0026] Figure 3 It is an actual engineering drawing of a core mold of a special-shaped structure of a braiding machine of the present invention;

[0027] Figure 4 A simple schematic diagram of a braiding machine of the present invention for braiding a special-shaped structure core mold;

[0028] Figure 5 It is a schematic diagram of the robot arm of the present invention pulling a heterogeneous structure core mold;

[0029] Figure 6 It is a module connection diagram of a weaving control system based on a special-shaped structure core mold of the present invention;

[0030] Figure 7 The actual pictures of the preforms woven by two methods in the embodiments of the present invention;

[0031] Figure 8 It is a comparison diagram of the braiding angles of the preforms braided by two methods in the embodiments of the present invention. DETAILED DESCRIPTION

[0032] The specific embodiments of the present invention will be described in detail below. It should be noted that the embodiments described herein are only for illustration and are not intended to limit the present invention. In the following description, a large number of specific details are set forth in order to provide a thorough understanding of the present invention. However, it is obvious to those of ordinary skill in the art that these specific details do not need to be adopted to implement the present invention. In other examples, in order to avoid confusing the present invention, known circuits, software or methods are not specifically described.

[0033] Throughout the specification, references to "one embodiment," "an embodiment," "an example," or "an example" mean that a particular feature, structure, or characteristic described in conjunction with the embodiment or example is included in at least one embodiment of the present invention. Therefore, the phrases "in one embodiment," "in an embodiment," "an example," or "an example" appearing in various places throughout the specification do not necessarily all refer to the same embodiment or example. In addition, particular features, structures, or characteristics may be combined in one or more embodiments or examples in any suitable combination and / or subcombination. In addition, it should be understood by those of ordinary skill in the art that the figures provided herein are for illustrative purposes and that the figures are not necessarily drawn to scale.

[0034] See also Figure 1 In one embodiment, the present invention provides a weaving control method based on a special-shaped structure core mold, comprising the following steps:

[0035] S1. Discretize the special-shaped structure core mode into multiple equivalent core modes.

[0036] In an alternative embodiment, see Figure 2 The method of discretizing the special-shaped structure core model into multiple equivalent core models includes the following steps: discretizing the special-shaped structure core model into multiple cylinders of equal length according to the morphological characteristics of the special-shaped structure core model; approximately equivalent the cylinder to a cylinder, and using the cylinder to obtain an equivalent core model, the approximate radius r of the cylinder i Satisfies the following formula:

[0037]

[0038] Where i = 1, 2, ..., n, i represents the discrete point number on the center axis of the special-shaped core mold, r O(i-1) Indicates the cross-sectional radius corresponding to the discrete point number i-1, r O(i) Indicates the cross-sectional radius corresponding to the discrete point number i.

[0039] In an optional embodiment, the special-shaped structural core mold is discretized into multiple cylinders of equal length according to the morphological characteristics of the special-shaped structural core mold, including the following steps: taking the cross-section where the starting weaving point of the special-shaped structural core mold is located as the starting cross-section; taking the cross-section where the ending weaving point of the special-shaped structural core mold is located as the ending cross-section; extracting the central axis of the special-shaped structural core mold, and defining discrete starting points O(0) and O(n) in combination with the starting cross-section and the ending cross-section; using n-1 points equidistant on the central axis to cut the special-shaped structural core mold into multiple cylinders of length d, specifically, the value of the length d is the expected weaving length of the equivalent core mold corresponding to the cylinder.

[0040] S2. Setting the expected braiding speed, expected convergence length and expected braiding length of the equivalent core mold in the current braiding stage.

[0041] In an alternative embodiment, see Figure 3 , Figure 3 This is a schematic diagram of the engineering process of weaving a special-shaped structure core mold for a weaving machine. Figure 2 In the figure, A represents the guide ring of the braiding machine, B represents the braid outside the special-shaped structure core mold, the angle formed by the braiding material on the braid is the braiding angle, and h represents the convergence distance. In this embodiment, the expected braiding speed is the ideal braiding speed set in the actual project, which needs to be adjusted by the traction speed so that the actual braiding speed is close to the expected braiding speed. When the braiding speed does not reach the expected braiding speed and approaches the expected braiding speed, the working state of the braiding machine is unstable. Therefore, in addition to advancing the equivalent core mold, it is also necessary to adjust the traction speed so that the braiding speed is stabilized to the expected braiding speed at this stage; when the braiding speed has approached the expected braiding speed, the working state of the braiding machine is stable. At this stage, it is necessary to continue to stably advance the equivalent core mold and keep the braiding speed stable on the premise that the equivalent core mold has been advanced for a certain distance. The target braiding length is set according to the discrete state of the equivalent core mold. In this embodiment, the target braiding length of the equivalent core mold is equal to the length of the equivalent core mold. The specific value is divided by the operator according to the structural state of the special-shaped core mold, that is, the multi-segment equivalent core mold after discretization and equivalent can characterize the structural characteristics (curvature change) of the special-shaped core mold. The expected convergence length is the convergence length value in the stable braiding process. By setting the expected convergence length to control the stable trend of the convergence length, each equivalent core mold has a fixed braiding angle. In this embodiment, please refer to Figure 4 , Figure 4 A and B with Figure 3 A and B represent the same object, C represents the propulsion direction, D represents the rotation direction of the guide ring, and θ represents the braiding angle. The braiding angle θ satisfies the following formula:

[0042]

[0043] Where θ represents the braiding angle, R represents the radius of the guide ring, and r i represents the approximate radius of the i-th equivalent core mode; h(i) represents the convergence length of the i-th equivalent core mode.

[0044] S3, advancing the equivalent core mold, and adjusting the pulling speed of the equivalent core mold, so that the braiding speed of the braiding machine approaches the expected braiding speed.

[0045] In an optional embodiment, the advancing the equivalent core mold and adjusting the traction speed of the equivalent core mold so that the weaving speed of the braiding machine approaches the expected weaving speed include the following steps: setting a first advancing distance and advancing the equivalent core mold according to the first advancing distance; decomposing the traction speed of the equivalent core mold at the weaving point to obtain the weaving speed of the braiding machine and the moving speed of the weaving point; obtaining, through the weaving speed, a functional relationship between the weaving speed and time when the approximate radius of the equivalent core mold changes suddenly; and using the functional relationship between the weaving speed and time, adjusting the traction speed so that the weaving speed approaches the expected weaving speed.

[0046] In an optional embodiment, the first advancing distance satisfies the following formula:

[0047]

[0048] Wherein, d1 represents the first advancing distance, and L represents the target braiding length.

[0049] In an optional embodiment, the pulling speed at the braiding point can be obtained by synthesizing the braiding speed of the braiding machine and the braiding point moving speed, that is, the pulling speed at the point satisfies the following relationship:

[0050] V=V b +V p ,

[0051] Among them, V b Indicates the knitting speed, V p Indicates the moving speed of the knitting point. Specifically, when the knitting machine is in an unstable knitting state, the knitting point will change with time. p ≠0, that is, V=V b +V p ; When the braiding machine is in a stable braiding state, the braiding point, convergence length and braiding angle are all in a stable state. p =0, that is, V = V b .

[0052] In an optional embodiment, the method of obtaining the functional relationship of the weaving speed over time when the approximate radius of the equivalent core mold suddenly changes through the weaving speed includes the following steps: obtaining the differential relationship of the convergence length over time when the approximate radius of the equivalent core mold suddenly changes; obtaining a first-order linear differential equation of the convergence length over time through the differential relationship; setting the initial conditions of the first-order linear differential equation; using the initial conditions to solve the first-order linear differential equation to obtain the functional relationship of the convergence length over time; using the functional relationship of the convergence length over time, obtaining the functional relationship of the weaving speed over time.

[0053] In detail, in this embodiment, the functional relationship of the braiding speed changing with time when the approximate radius of the equivalent core mold suddenly changes is obtained through the braiding speed, including the following steps: obtaining the mathematical relationship between the braiding speed, the braiding angle and the braiding circumferential speed when the braiding machine is stably braiding, and the mathematical relationship satisfies the following formula:

[0054]

[0055] Among them, V b represents the weaving speed, ω represents the weaving circumferential speed, θ represents the weaving angle, r i Represents the approximate radius of the equivalent core mode of the i-th segment. Using mathematical relations, the approximate radius of the equivalent core mode is obtained by r i Mutation to r i+1 The mutation weaving speed satisfies the following formula:

[0056]

[0057] Among them, V bi represents the sudden braiding speed of the equivalent core mode of the i-th segment, h i (t) represents the convergence length of the equivalent core mode of the i-th segment, at this time h i (t) is unstable and is a value that changes with time. More specifically, the initial convergence length h0(i) of the i-th equivalent core mode can be taken as the convergence length h of the i-1-th equivalent core mode when it is stably woven. i-1 , R represents the guide wheel radius of the braiding machine. The differential relationship between the convergence length and time when the braiding machine is in an unstable braiding state is obtained, and the differential relationship satisfies the following expression:

[0058] Δh=V p Δt,

[0059] Among them, Δt represents the time length, Δh represents the length change of the convergence length within the time length of Δt, V pIndicates the moving speed of the braiding point. The differential relationship is combined with the decomposition of the traction speed to transform the differential relationship of the convergence length over time. After the transformation, the differential relationship of the convergence length over time satisfies the following formula:

[0060]

[0061] By deforming the differential relationship of the convergence length after conversion with time, a first-order linear differential equation of the convergence length can be obtained, and the first-order linear differential equation satisfies the following formula:

[0062]

[0063] At the same time, the general solution of the first-order linear differential equation can be obtained as Wherein, c is a constant coefficient. By setting the initial conditions and combining the initial conditions with the general solution of the first-order linear differential equation, the functional relationship of the convergence length changing with time is obtained, and the functional relationship of the convergence length changing with time satisfies the following formula:

[0064]

[0065] Among them, the initial conditions are t=0, h=h0(i), and h0(i) represents the initial convergence length of the equivalent core mode of the i-th segment. Since the change of the convergence length is caused by the change of the braiding point position after the sudden change of the radius, the functional relationship of the convergence length changing with time is derived with respect to time to obtain the functional relationship of the braiding point moving speed changing with time. The functional relationship of the braiding point moving speed changing with time satisfies the following formula:

[0066]

[0067] Among them, V p Indicates the knitting point moving speed.

[0068] By combining the weaving point moving speed with the decomposition of the pulling speed, the functional relationship of the weaving speed changing with time is obtained, and the functional relationship of the weaving speed changing with time satisfies the following formula:

[0069]

[0070] Among them, V b represents the weaving speed, V represents the pulling speed, r i represents the approximate radius of the equivalent core mold of the i-th section, and ω represents the braiding circumferential speed of the braiding machine.

[0071] In an optional embodiment, according to actual weaving engineering, in order to ensure that the braiding machine can enter the stable weaving stage as soon as possible, when adjusting the traction speed, the braiding length of the braided fabric on the equivalent core mold cannot be greater than the first advancement distance; at the same time, the corresponding braiding speed cannot exceed the expected braiding speed V e , so the set constraints satisfy the following equation:

[0072]

[0073] Among them, V b Indicates the knitting speed, V e represents the expected braiding speed; l represents the braiding length, and d1 represents the first advancement distance. If the braiding speed exceeds the expected braiding speed when adjusting the traction speed, or the braiding length of the braid on the equivalent core mold is greater than the first advancement distance, readjustment is performed.

[0074] S4. Adjust the advancement distance of the equivalent core mold according to the desired braiding length so that the braided fabric on the equivalent core mold reaches the desired braiding length.

[0075] In an optional embodiment, the method of adjusting the advancement distance of the equivalent core mold by the expected braiding length so that the braided fabric on the equivalent core mold reaches the expected braiding length includes the following steps: obtaining the braiding length within a first advancement distance by utilizing the functional relationship between the braiding speed and time; obtaining a second advancement distance by combining the braiding length with the expected braiding length; and advancing the equivalent core mold according to the second advancement distance so that the braided fabric on the equivalent core mold reaches the expected braiding length.

[0076] In an optional embodiment, the method of obtaining the braiding length of the braiding machine within the first advancement distance by utilizing the functional relationship between the braiding speed and time includes the following steps: obtaining the length of time consumed by the braiding machine in the process of advancing the first advancement distance; utilizing the time length in combination with the expected braiding speed to obtain the traction speed of the braiding machine within the first advancement distance; and obtaining the braiding length of the braiding machine within the first advancement distance by combining the traction speed, time length and the braiding speed with time.

[0077] In this embodiment, due to the existence of the unstable braiding stage, the robot's advancing distance and the braiding length formed on the special-shaped structure core mold are not equal in the same time of the advancing special-shaped structure core mold, and after entering the stable state, the advancing distance in the same time period is equal to the braiding length on the special-shaped structure core mold. In order to form the same braiding length on each section of the special-shaped structure core mold, it is necessary to adjust the advancing distance while ensuring the traction speed to compensate for the deviation caused by the unstable stage. At the same time, the braiding length of the braiding machine braided within the first advancing distance obtained satisfies the following formula:

[0078]

[0079] Among them, l i represents the braiding length of the i-th equivalent core mold braided by the braiding machine within the first advancement distance, t i represents the time length consumed by the braiding machine in advancing the first advancing distance, d1 represents the first advancing distance, h0(i) represents the initial convergence length of the i-th equivalent core mode, V represents the traction speed, r i represents the approximate radius of the equivalent core mold of the i-th section, ω represents the braiding circumferential speed of the braiding machine, and R represents the guide wheel radius of the braiding machine.

[0080] In an optional embodiment, the convergence length of the adjusted braiding machine is stable and the braiding angle is also stable. Specifically, the stable convergence length satisfies the following formula:

[0081]

[0082] Among them, h i represents the stable convergence length of the equivalent core mode of the i-th segment, h e represents the expected convergence length of the equivalent core mode, d1 represents the first advancement distance, V represents the pulling speed, r i represents the approximate radius of the equivalent core mold of the i-th section, ω represents the braiding circumferential speed of the braiding machine, and R represents the guide wheel radius of the braiding machine.

[0083] In an optional embodiment, in order to form the same braiding length on each section of the special-shaped structure core mold, the second advancement distance satisfies the following formula:

[0084] d2=Ll i ,

[0085] Where d2 represents the second advancement distance, L represents the desired braiding length, and l i It represents the braiding length of the i-th section equivalent core mold braided by the braiding machine within the first advancement distance.

[0086] In an alternative embodiment, see Figure 5 During the weaving process, the operation of pushing the special-shaped structure core mold is completed by the robot arm of the weaving machine. Figure 5 In the figure, E represents the robot arm and F represents the knitting machine.

[0087] The weaving control method based on the special-shaped structure core mold proposed in the present invention controls the weaving process of the braided fabric on each equivalent core mold obtained after discretization by respectively adjusting the traction speed in the unstable weaving stage and the advancement distance in the stable weaving stage. It not only controls the advancement distance of the weaving special-shaped structure core mold to make the weaving length on the core mold reach the expected length, but also realizes automatic adjustment of the braiding angle, so that the braiding angle is more stable and the overall braiding angle error is smaller, which solves the problem of unstable braiding angle caused by continuous change of the radius of the special-shaped structure core mold in the weaving process of the special-shaped structure core mold preform. At the same time, the weaving control method of the present invention is of great significance for innovating the weaving technology of the variable-section arbitrary curvature core mold.

[0088] See also Figure 6 The present invention also provides a weaving control system based on a special-shaped core mold, which is suitable for the weaving control method based on the special-shaped core mold described in the first aspect, including: a core mold discrete module, which is used to discretize the special-shaped core mold into multiple equivalent core molds; a data setting module, which is used to set the expected weaving speed, expected convergence length and expected weaving length of the equivalent core mold in the current weaving stage; a first adjustment module, which is used to advance the equivalent core mold and adjust the traction speed of the equivalent core mold so that the weaving speed of the weaving machine approaches the expected weaving speed; a second adjustment module, which is used to adjust the advancement distance of the equivalent core mold according to the expected weaving length so that the braided fabric on the equivalent core mold reaches the expected weaving length; a weaving cycle module, which is used to control the weaving cycle process according to the discrete result of the core mold discrete module. The weaving control system based on the special-shaped structure core mold works together through multiple modules to stably implement the weaving control method based on the special-shaped structure core mold, that is, to achieve stable control of the weaving angle by adjusting the traction speed in real time. At the same time, the system has a compact structure, stable operation, and is easy to install, which improves the practical applicability of the present invention.

[0089] In an optional embodiment, the weaving control system based on the special-shaped structure core mold of the present invention is used to weave a heterogeneous structure core mold with a cross-sectional radius of 26mm at the starting end and a cross-sectional radius of 59mm at the ending end. The weaving operation uses a spherical braiding machine and a spherical braiding machine. The spherical braiding machine contains 144 spindles, each of which has a yarn carrier. The motion system of the braiding machine includes 4 servo motors, 2 vibration motors and their respective controllers. During the weaving process, the angular velocity ω of the yarn carrier is 320rad / min, the angular velocity of the spindle rotation is 0.07rad / s, the frequency of the vibration motor is 46Hz, the length of each segment after the core mold is discretized is 50mm, and the first propulsion distance is 25mm. Please refer to Figure 7 ,in, Figure 7a represents a preform woven by a conventional control method, and b represents a preform woven by a woven control method based on a special-shaped structure mandrel provided by the present invention. The woven angles of each point are obtained by measuring the woven angles at the same position of the mandrel, see Figure 8 , Figure 8 The following is a comparison of the braiding angles of the preforms woven by the two methods. It can be seen from the figure that the control method that does not consider the change in the cross-sectional radius of the special-shaped core mold has a maximum difference of more than 8° between the braiding angle and the expected braiding angle. The unstable braiding angle also makes the quality of the preform low. The control method proposed in the present invention takes into account the change in the radial direction of the core mold, and stabilizes the braiding angle as soon as possible by adjusting the traction speed. It can be seen that the maximum difference between the braiding angle and the expected braiding angle is within 3°. It can be seen that the braiding quality of the preform is very high, which is of great significance to the braiding of the special-shaped core mold, making the braiding of the special-shaped core mold more efficient, the braiding angle more accurate, and the performance of the composite material better.

[0090] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein by equivalents. These modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention, and they should all be included in the scope of the claims and specification of the present invention.

Claims

1. A weaving control method based on a special-shaped structure core mold, characterized in that: The steps include: Discretize the core mode of the special-shaped structure into multiple equivalent core modes; Setting the expected braiding speed, expected convergence length and expected braiding length of the equivalent core mold in the current braiding stage; Propelling the equivalent core mold and adjusting the pulling speed of the equivalent core mold so that the braiding speed of the braiding machine approaches the expected braiding speed; Adjusting the advancement distance of the equivalent mandrel according to the desired braiding length so that the braid on the equivalent mandrel reaches the desired braiding length; The method of discretizing the special-shaped structure core mold into multiple sections of equivalent core molds includes the following steps: According to the morphological characteristics of the special-shaped structural core mold, the special-shaped structural core mold is discretized into multiple cylinders with equal lengths; The cylinder is approximately equivalent to a circular cylinder, and an equivalent core mold is obtained by using the circular cylinder. The approximate radius r of the circular cylinder is i Satisfies the following formula: Where i = 1, 2, ..., n, i represents the discrete point number on the center axis of the special-shaped core mold, r O(i-1) Indicates the cross-sectional radius corresponding to the discrete point number i-1, r O(i) Indicates the cross-sectional radius corresponding to the discrete point number i; The step of advancing the equivalent core mold and adjusting the pulling speed of the equivalent core mold so that the braiding speed of the braiding machine approaches the expected braiding speed comprises the following steps: Setting a first advancing distance, and advancing the equivalent core mold according to the first advancing distance; Decompose the pulling speed of the equivalent core mold at the braiding point to obtain the braiding speed of the braiding machine and the moving speed of the braiding point; By using the braiding speed, a functional relationship between the braiding speed and time when the approximate radius of the equivalent core mold changes suddenly is obtained; The pulling speed is adjusted by utilizing the functional relationship between the braiding speed and time so that the braiding speed approaches the expected braiding speed.

2. The braiding control method based on the special-shaped structure core mold according to claim 1 is characterized in that: The functional relationship between the braiding speed and time satisfies the following formula: Among them, V b represents the weaving speed, V represents the pulling speed, r i represents the approximate radius of the ith equivalent core mold, ω represents the braiding circumferential speed of the braiding machine, h0(i) represents the initial convergence length of the ith equivalent core mold, and R represents the guide wheel radius of the braiding machine.

3. The braiding control method based on the special-shaped structure core mold according to claim 1 is characterized in that: The method of obtaining the functional relationship between the braiding speed and time when the approximate radius of the equivalent core mold changes suddenly through the braiding speed comprises the following steps: Obtaining the differential relationship between the convergence length and time when the approximate radius of the equivalent core mode changes suddenly; Through the differential relationship, a first-order linear differential equation of the variation of the convergence length with time is obtained; Setting initial conditions of the first-order linear differential equation; Solving the first-order linear differential equation using the initial conditions to obtain a functional relationship between the convergence length and time; The functional relationship between the convergence length and time is used to obtain the functional relationship between the braiding speed and time.

4. The braiding control method based on the special-shaped structure core mold according to claim 3 is characterized in that: The functional relationship between the convergence length and time satisfies the following formula: Among them, h i (t) represents the time-varying convergence length, h0(i) represents the initial convergence length of the equivalent core mode of the i-th segment, V represents the pulling speed, r i represents the approximate radius of the equivalent core mold of the i-th section, ω represents the braiding circumferential speed of the braiding machine, and R represents the guide wheel radius of the braiding machine.

5. The braiding control method based on the special-shaped structure core mold according to claim 1 is characterized in that: The method of adjusting the advancement distance of the equivalent mandrel according to the desired braiding length so that the braided fabric on the equivalent mandrel reaches the desired braiding length comprises the following steps: Using the functional relationship between the braiding speed and time, the braiding length within the first advancing distance is obtained; Obtaining a second advancement distance by combining the braiding length with the expected braiding length; The equivalent mandrel is advanced according to the second advancement distance, so that the braided fabric on the equivalent mandrel reaches a desired braiding length.

6. The braiding control method based on the special-shaped structure core mold according to claim 5 is characterized in that: The method of obtaining the braiding length of the braiding machine within the first advancement distance by utilizing the functional relationship between the braiding speed and the time includes the following steps: Obtaining the length of time the braiding machine consumes in the process of advancing the first advancing distance; Using the time length in combination with a desired braiding speed, a pulling speed of the braiding machine within a first advancing distance is obtained; The pulling speed, the time length and the time variation of the braiding speed are combined to obtain the braiding length braided by the braiding machine within the first advancing distance.

7. The braiding control method based on the special-shaped structure core mold according to claim 5 is characterized in that: The braiding length satisfies the following formula: Among them, l i represents the braiding length of the i-th equivalent core mold braided by the braiding machine within the first advancement distance, t i represents the time length consumed by the braiding machine in advancing the first advancing distance, d1 represents the first advancing distance, h0(i) represents the initial convergence length of the i-th equivalent core mode, V represents the traction speed, r i represents the approximate radius of the equivalent core mold of the i-th section, ω represents the braiding circumferential speed of the braiding machine, and R represents the guide wheel radius of the braiding machine.

8. The braiding control method based on the special-shaped structure core mold according to claim 5 is characterized in that: The second advancement distance satisfies the following formula: <h2 style=";text-align:left;direction:ltr">d2=Ll<h2 style=";text-align:left;direction:ltr"> i <h2 style=";text-align:left;direction:ltr"> , Where d2 represents the second advancement distance, L represents the desired braiding length, and l i It represents the braiding length of the i-th section equivalent core mold braided by the braiding machine within the first advancement distance.

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