Device and method for monitoring automatic wire laying process

Abstract

The present invention discloses an automatic wire laying process monitoring device and method, which belongs to the field of thermoplastic composite material manufacturing. The method adopts the advantages of fiber grating sensors, such as small size and high precision, and lays the fiber grating sensors between the layers of the thermoplastic composite material flat plate to achieve the bonding of the fiber optic sensor and the thermoplastic preload material; and steers the fiber optic sensor through a directional wheel to achieve real-time monitoring of the stress field and temperature field of multiple thermoplastic composite materials during the production and curing process by one fiber optic grating sensor. The method is suitable for the field of thermoplastic composite material manufacturing, and provides quantitative data support for the molding process through real-time monitoring of the stress field and temperature field during the production process.

Description

Technical Field

[0001] The invention relates to monitoring of stress field and temperature field during thermoplastic prepreg tape laying, and in particular to a device and method for monitoring automatic wire laying process, belonging to the field of thermoplastic composite material manufacturing. Background Art

[0002] Thermoplastic composites are a type of composite material that is formed by external pressure. Compared with thermosetting composites, they have the same or even better mechanical properties. In addition, during the production process, they eliminate complex steps such as autoclaves, saving the production cost of composite materials and have great development prospects.

[0003] During the production process of thermoplastic composite flat plates, the surface accuracy of the molded parts is closely related to the input parameters of the automatic wire laying machine during laying, including the temperature of the prepreg heating source, the speed of the pressure roller, the pressure of the pressure roller, etc. Among them, the choice of temperature when the heating source heats the prepreg has an important influence on the molding of thermoplastic composite materials. If the temperature of the heating source is too high, it will cause thermal aging or curing of the resin matrix; if the temperature is too low, the thermoplastic composite material will not be completely melted, the viscosity is insufficient, and the material will have local defects. The pressure and speed of the pressure roller are also an important factor affecting the molding of thermoplastic composite materials. If the pressure or speed is too high, the temperature inside the composite material will be too high, and large residual stress will be generated during the cooling process, causing defects such as warping and wrinkling in the composite material; if the pressure is too low, it will cause incomplete bonding between each layer of material, causing the material to slip, etc., affecting the subsequent laying of the material.

[0004] The existing thermoplastic composite flat plate manufacturing device uses the pressure roller's built-in sensor to reflect the pressure applied during the laying process of the thermoplastic composite material, and uses a thermal imaging device to monitor the temperature change on the composite material surface. However, this method can only reflect the pressure applied during the production process of the thermoplastic composite material and the temperature change on the composite material surface, while the release of residual stress in the thermoplastic composite material during the curing process is the result of its internal temperature and stress. Therefore, adjusting the pressure and temperature parameters during the laying process of the thermoplastic composite flat plate based on the pressure roller sensor and thermal imaging monitoring results often does not achieve good surface accuracy. Summary of the invention

[0005] In view of the problem that the existing thermoplastic composite flat plate manufacturing device cannot reflect the internal temperature and pressure of the composite material, the present invention provides a device and method for automatically monitoring the wire placement process, with the purpose of realizing real-time monitoring of the temperature field and stress field of the thermoplastic material during the manufacturing and curing process, and providing quantitative data support for the molding process of the thermoplastic composite material.

[0006] The objective of the present invention is achieved through the following technical solutions:

[0007] The present invention discloses a device for monitoring the automatic wire laying process, which adopts the advantages of fiber grating sensors such as small size and high precision. The fiber grating sensors are laid between layers of thermoplastic composite flat plates to monitor the internal stress and temperature of the thermoplastic composite flat plates during laying and curing, and provide guidance for parameter input when laying the thermoplastic composite flat plates.

[0008] The present invention discloses a monitoring device for an automatic fiber placement process, comprising a thermoplastic composite material prepreg tape fixing workbench, an optical fiber preload adjustment mechanism, a thermoplastic composite material prepreg tape laying device, an optical fiber guiding mechanism, a fiber Bragg grating (FBG) sensor, and an optical fiber grating demodulation system.

[0009] The thermoplastic composite material prepreg tape fixing workbench is used for thermoplastic composite material prepreg.

[0010] The optical fiber preload force adjustment mechanism includes a damper and an optical fiber orientation wheel, which can be fixed in the groove of the thermoplastic composite material prepreg fixed workbench according to the actual needs during laying. The damper is used to adjust the preload force applied by the optical fiber grating sensor, and the orientation wheel is used to determine the direction of the optical fiber to prevent directional deviation caused by factors such as the external environment.

[0011] The optical fiber guiding mechanism is used for steering the optical fiber sensor, protecting the energy signal of the sensor from loss during the steering process, and realizing the monitoring of multiple prepreg tapes of one optical fiber.

[0012] The thermoplastic composite material prepreg tape laying device is used for laying and pressing the prepreg tape to ensure that the fiber grating sensor is completely attached to the thermoplastic composite material prepreg tape, realizes synchronous deformation with the prepreg tape, and achieves the purpose of measuring strain.

[0013] The fiber Bragg grating sensor is used to measure in real time the changes in the temperature field and stress field of the prepreg during the laying, cooling and curing process.

[0014] The fiber Bragg grating demodulation system includes a fiber Bragg grating demodulator, a computer terminal and corresponding demodulation software, which is used to demodulate the optical signal value generated by the fiber Bragg grating measurement into an electrical signal and a strain value, so as to realize real-time monitoring of the thermoplastic composite material during the production process.

[0015] The groove edge of the thermoplastic composite material prepreg tape fixing workbench is provided with scales, and the optical fiber preload adjustment mechanism and the optical fiber guide mechanism are movable mechanisms, which can be slid and fixed in the groove. The number of the modules can be adjusted according to actual needs and the length of the optical fiber, and the position of the module can be adjusted according to the laying position of the thermoplastic composite material and the node that needs to be monitored.

[0016] The optical fiber preload adjustment mechanism includes a damper and an orienting wheel. The damper is used to give the optical fiber a certain preload to keep its tension. The orienting wheel is used to ensure that during the laying process, the optical fiber can remain parallel under the action of the laying roller to ensure the accuracy of monitoring.

[0017] The wheel disc and the base support of the optical fiber guide wheel are movable, and the size of the guide wheel can be replaced according to the actual monitoring width of the optical fiber to achieve flexible monitoring.

[0018] The pressure roller of the thermoplastic composite material prepreg tape laying device is made of silicone rubber. During the laying process, the fiber grating sensor must be placed between two thermoplastic composite material prepreg tapes, and the direction must be kept parallel to the thermoplastic prepreg tapes, so that the thermoplastic prepreg tapes can protect the fiber grating sensor from being affected by the local shear force generated by the uneven pressure of the pressure roller during the laying process.

[0019] The present invention discloses an automatic wire laying process monitoring method, which is implemented based on the automatic wire laying process monitoring device, and comprises the following steps:

[0020] Step 1: Determine the laying interval of the fiber grating sensor to determine the diameter of the guide wheel;

[0021] Step 2: determine the position of the prepreg tape to be monitored, adjust the number of guide wheels and preload adjustment devices, and fix the two after determining the position;

[0022] Step 3: Calculate the position of the point to be monitored on the thermoplastic prepreg tape in advance, and calculate the length of the grating so that the sensing part of the grating is at the position of the monitored point;

[0023] Step 4: Pass one end of the fiber grating sensor through the damper and the directional wheel in the fiber preload adjustment mechanism to set the preload on the fiber, and bypass the guide wheel to connect the other end to the fiber preload adjustment mechanism at the tail end; the fiber grating sensor should be placed between two layers of thermoplastic composite prepreg tapes to ensure better adhesion of the composite material and improve monitoring accuracy;

[0024] Step 5: The head end of the optical fiber is connected to a fiber Bragg grating demodulator, and the fiber Bragg grating demodulator is connected to a computer terminal;

[0025] Step 6: Open the corresponding monitoring software, check whether the energy of the installed fiber grating sensor is normal, check whether the preload force meets the requirements, and reset the fiber preload force to zero;

[0026] Step 7: Start the thermoplastic composite prepreg tape laying device, bury the fiber grating sensor into the thermoplastic composite material, monitor the stress field and temperature field during the laying process and the cooling and curing process, and record the procedure data in real time, so as to realize the monitoring of the automatic laying process.

[0027] Beneficial effects:

[0028] The present invention discloses an automatic wire laying process monitoring device and method, which at least have the following beneficial effects:

[0029] (1) It is possible to embed the fiber optic Bragg grating sensor and to fit the fiber optic Bragg grating sensor to the thermoplastic preload material. The fiber optic Bragg grating sensor can be monitored in real time under the pressure of the roller without being damaged.

[0030] (2) A single optical fiber can monitor multiple points on multiple prepreg tapes;

[0031] (3) It is capable of real-time monitoring of the stress field and temperature field of thermoplastic composite materials during the production and curing process. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 This is a schematic diagram of the structure of an automatic wire laying process monitoring device proposed by the present invention;

[0033] Figure 2 It is a structural schematic diagram of the optical fiber preload adjustment mechanism;

[0034] in:

[0035] 1-fixed workbench for thermoplastic composite material prepreg; 2-optical fiber preload adjustment mechanism; 3-optical fiber guide mechanism; 4-pressing roller for laying thermoplastic composite material prepreg; 5-thermoplastic composite material prepreg; 6-fiber Bragg grating (FBG) sensor; 7-fiber Bragg grating demodulator; 8-computer data acquisition terminal; 2-1-damper for adjusting optical fiber preload; 2-2-directional wheel for maintaining fiber direction. DETAILED DESCRIPTION

[0036] The present invention will be described in detail below with reference to the accompanying drawings and embodiments. The technical problems solved by the technical solution of the present invention and the beneficial effects are also described. It should be noted that the described embodiments are only intended to facilitate the understanding of the present invention and do not have any limiting effect on it.

[0037] like Figure 1 As shown, the monitoring device for an automatic fiber placement process disclosed in this embodiment includes a thermoplastic composite material prepreg fixed workbench 1, an optical fiber preload adjustment mechanism 2, an optical fiber guide mechanism 3, a thermoplastic composite material prepreg placement roller 4, a fiber Bragg grating (FBG) sensor 6, a fiber Bragg grating demodulator 7; and a computer data acquisition terminal 8.

[0038] The thermoplastic composite material prepreg tape fixing workbench 1 is used for thermoplastic composite material prepreg.

[0039] Optical fiber preload adjustment mechanism 2 Figure 2As shown, it includes a damper 2-1 for adjusting the preload force of the optical fiber and an orientation wheel 2-2 for maintaining the direction of the fiber. According to the actual position during laying, it is fixed in the groove of the above-mentioned thermoplastic composite material prepreg tape fixing workbench 1. The damper 2-1 for adjusting the preload force applied by the fiber grating sensor is used to adjust the preload force applied by the fiber grating sensor, and the orientation wheel 2-2 for maintaining the direction of the fiber is used to determine the direction of the optical fiber to prevent the direction deviation caused by factors such as the external environment.

[0040] The optical fiber guiding mechanism 3 is used for steering the optical fiber sensor, protecting the energy signal of the sensor from loss during the steering process, and realizing the monitoring of multiple prepreg tapes of one optical fiber.

[0041] The thermoplastic composite material prepreg tape laying roller 4 is made of silicone rubber and is used for laying and pressing the prepreg tape. The optical fiber is laid between the thermoplastic prepreg tapes to ensure that the fiber grating sensor is completely attached to the thermoplastic composite material prepreg tape, and realizes synchronous deformation with the prepreg tape to achieve the purpose of measuring strain.

[0042] The fiber Bragg grating sensor 6 is used to measure in real time the changes in the temperature field and stress field of the prepreg tape during the laying, cooling and curing process.

[0043] The fiber Bragg grating demodulation system includes a fiber Bragg grating demodulator 7, a computer data acquisition terminal 8 and corresponding demodulation software, which is used to demodulate the optical signal value generated by the fiber Bragg grating measurement into an electrical signal and a strain value, so as to realize real-time monitoring of the thermoplastic composite material during the production process.

[0044] The groove edge of the thermoplastic composite material prepreg tape fixing workbench 1 is provided with scales. The optical fiber preload adjustment mechanism 2 and the optical fiber guide mechanism 3 are movable mechanisms, which can slide and be fixed in the groove, and the number of the modules can be adjusted according to actual needs and the length of the optical fiber, and the position of the module can be adjusted according to the laying position of the thermoplastic composite material and the node to be monitored.

[0045] The optical fiber preload adjustment mechanism includes a damper 2-1 for adjusting the optical fiber preload and an oriented wheel 2-2 for maintaining the fiber direction. The damper 2-1 for adjusting the optical fiber preload is used to give the optical fiber a certain preload to keep its tension; the oriented wheel 2-2 for maintaining the fiber direction ensures that during the laying process, under the action of the thermoplastic composite material prepreg tape laying roller 4, the optical fiber can remain parallel to ensure the accuracy of monitoring. The optical fiber preload is maintained at 2N, and the optical fiber laying direction is kept parallel to the thermoplastic prepreg tape.

[0046] The optical fiber guiding mechanism 3, the wheel disc and the base support are movable, and the size of the guide wheel can be changed according to the actual monitoring width of the optical fiber to achieve flexible monitoring.

[0047] During the laying process, the fiber grating sensor must be placed between two thermoplastic composite prepreg tapes so that the thermoplastic prepreg tapes can protect the fiber grating sensor from the influence of the local shear force caused by the uneven pressure of the roller during the laying process.

[0048] The two rollers of the directional wheel 2-2 for maintaining the fiber direction are made of silicone rubber, and the pre-tightening force on the optical fiber is maintained at 0N to 15N.

[0049] The present embodiment discloses an automatic wire laying process monitoring method, which is implemented based on the automatic wire laying process monitoring device.

[0050] Step 1: determine the laying interval of the fiber grating sensor, which is used to determine the diameter of the guide wheel of the fiber guide mechanism 3; Step 2: determine the position of the prepreg tape that needs to be monitored, adjust the number of the fiber guide mechanism 3 and the fiber preload adjustment mechanism 2, and fix the two after determining the position; Step 3: calculate the position of the point that needs to be monitored in the thermoplastic prepreg tape in advance, and calculate the length of the grating at the same time, so that the grating sensing part is at the position of the monitored point; Step 4: pass one end of the fiber grating sensor through the damper 2-1 for adjusting the fiber preload and the fiber direction maintaining damper and directional wheel 2-2 in the fiber preload adjustment mechanism 2, set its preload force on the optical fiber to 2N, and the other end bypasses the guide wheel of the fiber guide mechanism 3 and connects to the fiber preload at the tail end In the adjustment mechanism 2; the fiber grating sensor should be placed between two layers of thermoplastic composite prepreg tapes 5 to ensure better adhesion of the composite material and improve monitoring accuracy; step five, the head end of the optical fiber is connected to the fiber grating demodulator 7, and the fiber grating demodulator 7 is connected to the computer data acquisition terminal 8; step six, open the corresponding monitoring software, check whether the energy of the installed fiber grating sensor is normal, check whether the preload force meets the requirements, and reset the fiber preload force to zero; step seven, start the thermoplastic composite prepreg tape laying roller 4, bury the fiber grating sensor in the thermoplastic composite material, monitor the stress field and temperature field during the laying process and the cooling and curing process, record the procedure data in real time, and provide guidance for parameter adjustment.

[0051] The monitoring method of the automatic wire laying process of thermoplastic composite materials disclosed in the present embodiment realizes the temperature and stress measurement of the thermoplastic composite materials during the production process through the fiber grating sensor, can provide the residual stress inside the material during curing, and provide the stress-temperature change of the material during the production process. According to the collected data and in combination with the molding conditions of the thermoplastic composite materials, the various technical parameters (temperature, pressure, laying speed, etc.) of the wire laying machine can be appropriately adjusted to find the temperature and pressure windows suitable for laying, thereby improving the production success rate of the thermoplastic composite materials and improving the molding technology of the composite materials.

[0052] The specific description above further illustrates the purpose, technical solutions and beneficial effects of the invention in detail. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A monitoring device for an automatic wire laying process, characterized in that: It includes a thermoplastic composite material prepreg tape fixing workbench, an optical fiber preload adjustment mechanism, a thermoplastic composite material prepreg tape laying device, an optical fiber guiding mechanism, an optical fiber Bragg grating sensor, and an optical fiber Bragg grating demodulation system; The thermoplastic composite material prepreg tape fixing workbench is used for thermoplastic composite material prepreg; The optical fiber preload adjustment mechanism includes a damper and an optical fiber orientation wheel, which are fixed in the groove of the thermoplastic composite material prepreg fixed workbench according to the actual needs of laying, the damper is used to adjust the preload applied by the optical fiber grating sensor, and the orientation wheel is used to determine the direction of the optical fiber to prevent the direction deviation caused by the external environmental factors; The optical fiber guide mechanism is used for steering the optical fiber sensor, protecting the energy signal of the sensor from loss during the steering process, and realizing the monitoring of multiple prepreg tapes of one optical fiber; The thermoplastic composite material prepreg tape laying device is used for laying and pressing the prepreg tape to ensure that the fiber grating sensor is completely attached to the thermoplastic composite material prepreg tape, realizes synchronous deformation with the prepreg tape, and achieves the purpose of measuring strain; The fiber Bragg grating sensor is used to measure in real time the changes in the temperature field and stress field of the prepreg during the laying, cooling and curing process; The fiber Bragg grating demodulation system includes a fiber Bragg grating demodulator, a computer terminal and corresponding demodulation software, which is used to demodulate the optical signal value generated by the fiber Bragg grating measurement into an electrical signal and a strain value, so as to realize real-time monitoring of the thermoplastic composite material during the production process; The groove edge of the thermoplastic composite material prepreg tape fixing workbench is provided with scales, and the optical fiber preload adjustment mechanism and the optical fiber guide mechanism are movable mechanisms, which are slidably fixed in the groove. The number of modules is adjusted according to actual needs and the length of the optical fiber, and the position of the module is adjusted according to the laying position of the thermoplastic composite material and the node that needs to be monitored.

2. The monitoring device for an automatic wire laying process according to claim 1, characterized in that: The optical fiber preload adjustment mechanism includes a damper and an orienting wheel. The damper is used to give the optical fiber a certain preload to keep its tension. The orienting wheel is used to ensure that during the laying process, the optical fiber can remain parallel under the action of the laying roller to ensure the accuracy of monitoring.

3. The monitoring device for an automatic wire laying process according to claim 1, characterized in that: The wheel disc and the base support of the optical fiber guide wheel are movable, and the size of the guide wheel can be changed according to the actual monitoring width of the optical fiber, thereby realizing flexible monitoring.

4. The monitoring device for an automatic wire laying process according to claim 1, characterized in that: The pressure roller of the thermoplastic composite material prepreg tape laying device is made of silicone rubber. During the laying process, the fiber grating sensor must be placed between two thermoplastic composite material prepreg tapes, and the direction must be kept parallel to the thermoplastic prepreg tapes, so that the thermoplastic prepreg tapes can protect the fiber grating sensor from being affected by the local shear force generated by the uneven pressure of the pressure roller during the laying process.

5. A method for monitoring an automatic wire placement process, implemented based on an automatic wire placement process monitoring device according to claim 1, 2, 3 or 4, characterized in that: The steps include: Step 1: Determine the laying interval of the fiber grating sensor to determine the diameter of the guide wheel; Step 2: determine the position of the prepreg tape to be monitored, adjust the number of guide wheels and preload adjustment devices, and fix the two after determining the position; Step 3: Calculate the position of the point to be monitored on the thermoplastic prepreg tape in advance, and calculate the length of the grating so that the sensing part of the grating is at the position of the monitored point; Step 4: Pass one end of the fiber grating sensor through the damper and the directional wheel in the fiber preload adjustment mechanism to set the preload on the fiber, and bypass the guide wheel to connect the other end to the fiber preload adjustment mechanism at the tail end; the fiber grating sensor should be placed between two layers of thermoplastic composite prepreg tapes to ensure better adhesion of the composite material and improve monitoring accuracy; Step 5: The head end of the optical fiber is connected to a fiber Bragg grating demodulator, and the fiber Bragg grating demodulator is connected to a computer terminal; Step 6: Open the corresponding monitoring software, check whether the energy of the installed fiber grating sensor is normal, check whether the preload force meets the requirements, and reset the fiber preload force to zero; Step 7: Start the thermoplastic composite prepreg tape laying device, bury the fiber grating sensor into the thermoplastic composite material, monitor the stress field and temperature field during the laying process and the cooling and curing process, and record the procedure data in real time, so as to realize the monitoring of the automatic laying process.

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