A non-contact tension stability control method for the three-dimensional weaving process of composite materials

Abstract

The present invention discloses a non-contact tension stable control method for the three-dimensional braiding forming process of composite materials, which relates to the field of composite material forming manufacturing. This method detects the consumption speed of carbon fiber yarns through a camera, controls the motor speed on the active yarn carrier, so that the yarn winding and unwinding speed of the yarn carrier is equal to the consumption speed of the braiding yarns, and maintains the stable and controllable yarn tension. Based on the vision detection method, the present invention can realize the tension control of multiple yarns with different motion trajectories at the same time, reduce the use of tension measuring instruments and the direct contact between the instruments and the yarns, reduce the wear degree of the yarns, improve the automation degree of the preform manufacturing process, and form high-quality composite material preforms.

Description

Technical Field

[0001] The present invention relates to the field of composite material forming manufacturing, and particularly relates to a non-contact tension stability control method for the three-dimensional weaving process of composite materials. Background Art

[0002] Since the 1960s of the last century, the research on integral preforms with complex shapes using three-dimensional braiding technology has gradually increased. Compared with the traditional two-dimensional braiding process, it has good performance, flexible and variable braiding structures, and can form various special-shaped structures. Currently, carbon fiber composite materials have broad application prospects in various fields.

[0003] Regarding the production process of composite material preforms, research is carried out on how to further improve the degree of automation and product quality. During the braiding process, if the yarn tension is too large, it is easy to cause wear between the yarn and the weaving equipment, reducing the quality of the fiber bundle. In severe cases, the yarn breakage problem will occur. If the tension is too small, it will cause looseness inside the fabric, affecting the performance of the preform.

[0004] The existing tension control method is that during the production process, the tension control device directly contacts the carbon fiber relying on the tension sensor, resulting in problems such as a wide numerical fluctuation range, carbon fiber wear, and a lot of fluff in the tension regulation process, seriously affecting the quality of the three-dimensional woven preform of composite materials.

[0005] Therefore, a new technical solution is needed to solve the above problems. Summary of the Invention

[0006] The purpose of the present invention is to provide a non-contact tension stability control method for the three-dimensional weaving process of composite materials to solve the tension control problem in the fiber contact test during the three-dimensional braiding process and maintain the stability of the yarn tension during the braiding process.

[0007] To solve the above problems, the non-contact tension stability control method for the three-dimensional weaving process of composite materials provided by the present invention can adopt the following technical solutions:

[0008] A non-contact tension stability control method for the three-dimensional weaving process of composite materials includes the following steps:

[0009] (1) Set the feature points to be detected in braiding: Set feature points on the yarn carrier and the core mold as the targets for visual detection;

[0010] (2) Identify the spatial coordinates of the feature points: Set up visual detection equipment, take images at fixed intervals, locate the feature points on the yarn carrier and the core mold through the taken images, and calculate the spatial coordinates and relative position relationships of the yarn carrier and the core mold;

[0011] (3) Detection of the current speed of the yarn: Compare the spatial position of the feature points detected each time with the image measured last time to obtain the yarn consumption speed and judge the winding and unwinding speeds of the active control.

[0012] (4) Motor speed control: Transmit the data to the control module, and the control module controls the motor speed.

[0013] (5) The yarn carrier increases the unwinding speed: If the measured speed is greater than the actual speed, increase the unwinding speed of the yarn carrier to reduce the speed of the yarn carrier or reverse the yarn carrier; if the measured speed is less than the actual speed, reduce the unwinding speed of the yarn carrier or rotate the motor in the opposite direction to wind the yarn.

[0014] Further, in step (3), obtain the core mold feature point coordinates, yarn carrier feature point coordinates, and yarn interweaving point coordinates every time interval t, where the number of yarn interweaving point coordinates is zero, one, or more; segment the yarn according to the number of yarn interweaving points, and determine the length of each segment of the yarn based on the spatial position, core mold shape, and yarn carrier position as the measured length this time, compare it with the length measured last time to obtain the length difference, and combine the time interval t to obtain the yarn speed.

[0015] Further, this control method is used to achieve non-contact control of the tension during speed detection and tension control.

[0016] Further, the visual detection device selects a binocular camera.

[0017] Further, the feature points on the core mold are the starting points of the braided yarns on the core mold, and the feature points of the yarn carrier are the yarn outlets.

[0018] Further, the control module selects a PLC or a microprocessor, and the controlled motor selects a stepper motor or a servo motor.

[0019] Further, a mechanical tension buffer device is added to the yarn carrier to improve the tension control effect.

[0020] Further, in step (3), the yarn speed is detected by a host computer, and data is transmitted between the control module and the host computer by a data cable or wireless communication.

[0021] Further, the yarn on the yarn carrier selects carbon fiber or quartz fiber materials.

[0022] Further, in step (5), the motor controls the winding and unwinding speeds of the yarn carrier to keep the speeds at both ends of the yarn consistent and achieve uniform motion.

[0023] Beneficial effects: Compared with the prior art, the beneficial effects of the present invention are as follows:

[0024] 1. The present invention can simultaneously detect the motion states of multiple yarns, and separately drive motors to control the winding and unwinding speeds, maintain the stability of the yarn tension, and improve the automation degree of the three-dimensional braiding process.

[0025] 2. The present invention adopts a non-contact method for detecting yarn parameters, which can effectively reduce the damage of the measuring instrument to the yarn, reduce the space occupied by the detection instrument, and make the design of the three-dimensional braiding equipment more flexible. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a schematic diagram of the hardware structure adopted in the three-dimensional weaving process of the present invention.

[0027] Figure 2 It is a schematic diagram when the yarn carriers A and B move to the first position in an embodiment of the present invention.

[0028] Figure 3 It is a schematic diagram when the yarn carriers A and B move to the second position in an embodiment of the present invention.

[0029] Figure 4 It is a flow chart of the tension control method of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0030] The drawings disclose some embodiments of the present invention non-restrictively. The present invention will be further described below in conjunction with specific embodiments.

[0031] As Figure 1 shown, it is a schematic structure of the device for three-dimensional weaving of composite materials adopted in this embodiment, which includes a visual detection device 1, a host computer 2, a motor 31, a yarn carrier 32, and a mandrel 5. A cylindrical composite material preform is braided by this device. Among them, first, the target tension range during the braiding process is preset according to experience, an initial tension is added, the rotation speed of the yarn carrier is set, and the radius of the mandrel is R. During the braiding process, the motor 31 drives the yarn carrier 32 to move around the mandrel 5 according to a predetermined braiding trajectory. However, as the braiding progresses, the speeds of the two ends of the yarn 4 are inconsistent, resulting in tension fluctuations, and adjustment is required at this time.

[0032] For this device, the non-contact tension stability control method provided in this embodiment includes the following steps:

[0033] (1) Set the feature points to be detected during braiding: Feature points are set on the yarn carrier and the mandrel as the targets for visual detection; the feature point on the mandrel can be the starting point of the braiding yarn on the mandrel, and the feature point of the yarn carrier can be the yarn outlet. As Figure 2 shown, it is a state schematic when the yarn carriers A and B move to the first position. The coordinate of the feature point of the yarn carrier A is (x a1 , y a1 , z a1); The characteristic point coordinates of the yarn carrier B are (x b1 , y b1 , z b1 ); Two characteristic points are set on the mandrel, which are the starting points of the braided yarn on the mandrel, namely characteristic point A(x sa1 , y sa1 , z sa1 ) and the starting point, and characteristic point B(x sb1 , y sb1 , z sb1 ).

[0034] (2) Identification of characteristic point space coordinates: Set up a visual detection device to take images at fixed intervals, locate the characteristic points on the yarn carrier and the mandrel by taking images, and calculate the space coordinates and relative position relationship of the yarn carrier and the mandrel.

[0035] (3) Detection of the current speed of the yarn: Compare the space position of the characteristic point detected each time with the image measured last time to obtain the yarn consumption speed and judge the take-up and pay-off speed of the active control. In this embodiment, let Figure 2 be the space position of the characteristic point detected for the first time, and the length of the yarn corresponding to the yarn carrier A is:

[0036]

[0037] After a time t, the yarn carriers A and B move to Figure 3 position. At this time, the starting point of the yarn on the mandrel has changed, so new characteristic points A2(x sa , y sa2 , z sa2 ) of the new starting point and characteristic points B2(x sb , y sb , z sb ) of the new starting point are added. At this time, the length of the yarn corresponding to the yarn carrier A from the first detection to this detection is divided into three sections, namely characteristic point A - A2, characteristic point A2 - intersection point 1, and intersection point 1 - yarn carrier A. The corresponding yarn lengths are:

[0038]

[0039] Calculate the yarn consumption speed as:

[0040]

[0041] Save the length from characteristic point A2 to the yarn carrier A as the data for the next speed calculation.

[0042] (4) Motor speed control: Transmit the data to the control module, and the control module controls the motor speed;

[0043] (5) The yarn carrier increases the yarn feeding speed: If the measured speed is greater than the actual speed, the yarn feeding speed of the yarn carrier is increased to reduce the speed of the yarn carrier or reverse the yarn carrier; if the measured speed is less than the actual speed, the yarn feeding speed of the yarn carrier is decreased or the motor is rotated in the reverse direction to wind the yarn.

[0044] Repeat the above steps to continuously control the yarn tension during the knitting process.

Claims

1. A non-contact tension stability control method for the three-dimensional weaving process of a composite material, characterized in that It includes the following steps: (1) Set the feature points to be detected in weaving: Set feature points on the yarn carrier and the core mold as the targets for visual detection; (2) Identify the spatial coordinates of the feature points: Set up a visual detection device to take images at fixed intervals. Locate the feature points on the yarn carrier and the core mold by the captured images, and calculate the spatial coordinates and relative position relationship of the yarn carrier and the core mold; (3) Detect the current speed of the yarn: Compare the spatial positions of the feature points detected each time with the image measured last time to obtain the yarn consumption speed and judge the speed of the active control of yarn take-up and pay-off; (4) Control the motor speed: Transmit the data to the control module, and the control module controls the motor speed; (5) Adjust the pay-off speed of the yarn carrier: If the measured speed is greater than the actual speed, increase the pay-off speed of the yarn carrier; if the measured speed is less than the actual speed, decrease the pay-off speed of the yarn carrier; In step (3), obtain the coordinates of the feature points of the core mold, the coordinates of the feature points of the yarn carrier, and the coordinates of the yarn intersection points at every time t, where the number of yarn intersection points is zero, one or more; Segment the yarn according to the number of yarn intersection points, determine the length of each segment of the yarn based on the spatial position, the shape of the core mold, and the position of the yarn carrier, sum the lengths of each segment of the yarn as the length measured this time, compare it with the length measured last time to obtain the length difference, and combine with the time t to obtain the yarn speed.

2. The non-contact tension stability control method according to claim 1, characterized in that This control method is used to achieve non-contact control of tension during speed detection and tension control.

3. The non-contact tension stability control method according to claim 2, wherein The visual detection device selects a binocular camera.

4. The non-contact tension stable control method according to claim 1, wherein The feature points on the core mold are the starting points of the woven yarns on the core mold, and the feature points of the yarn carrier are the yarn outlets.

5. The non-contact tension stability control method according to claim 1, characterized in that The control module selects a plc or a microprocessor, and the controlled motor selects a stepper motor or a servo motor.

6. The non-contact tension stable control method according to claim 1, characterized in that, Add a mechanical tension buffer device to the yarn carrier to improve the tension control effect.

7. The non-contact tension stable control method according to claim 1, characterized in that Detect the yarn speed through the upper computer, and transmit data between the control module and the upper computer by data line or wireless communication.

8. The non-contact tension stability control method according to claim 1, wherein The yarn on the yarn carrier selects carbon fiber or quartz fiber material.

9. The non-contact tension stability control method according to claim 1, wherein In step (5), the motor controls the take-up and pay-off speed of the yarn carrier to keep the speeds at both ends of the yarn consistent and achieve uniform motion.

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