Fiber shortage detection method for composite material fiber placement machine

Abstract

The invention relates to the technical field of filament lacking detection, in particular to a composite filament lacking detection device and method, and the method comprises the steps: building a logic relation between filament lacking of tows and state variables in automatic laying control based on a tow transmission and filament laying head execution mechanism; real-time state variables of the tows in the automatic laying process are collected; and according to the real-time state variable, whether the tow is lack is judged in combination with the logic relationship. The composite material filament lacking detection device and method aim at solving the problem that laying quality detection and laying efficiency of a composite material are low.

Description

Technical Field

[0001] The invention relates to the technical field of wire shortage detection, and in particular to a wire shortage detection method for a composite material wire laying machine. Background Art

[0002] The automatic wire laying machine can realize the controllable wire bundles and can increase or decrease the number of prepreg bundles in real time to meet the actual laying needs. It is suitable for the automated forming of large-sized components with irregular shapes and complex boundaries, and is widely used in the laying and molding of large and complex composite parts. The composite parts laid on the tooling mold by the automatic wire laying machine usually consist of a three-layer structure of layers, strips, and bundles. The prepreg bundle is the basic unit of the composite parts. Its status detection and bundle laying control are the core of the automatic wire laying machine equipment control, including the control of feeding, cutting, rolling, heating and pneumatic components and the detection of missing wire bundles, which requires the coordinated work of multiple components.

[0003] The prepreg tow is loaded on the creel shaft. While the tow is being transmitted, the recycling roller recycles the protective film. The positioning roller measures the length of the tow transmission through the installed angle encoder. The tension reduction mechanism controls the low tension of the tow and transmits the tow to the tow guiding system. Under the action of the tow guiding system, the tow passes through the feeding, pressing and cutting mechanisms of the laying head and is then transmitted to the laying surface heated by the heating mechanism. The tow fits tightly to the mold surface under the rolling of the pressure roller, and the laying of the tow is finally completed. During the automatic laying process, it is necessary to detect and control the tow shielding, program usage status, feeding position, cutting position, margin detection, tension, missing wire, etc. When the tow has a quality defect of missing wire, the tow needs to be automatically supplemented.

[0004] Therefore, the inventor provides a method for detecting wire shortage in a composite material wire laying machine. Summary of the invention

[0005] (1) Technical issues to be solved

[0006] The embodiment of the present invention provides a method for detecting wire shortage in a composite material placing machine, which solves the technical problems of composite material placing quality detection and low placing efficiency.

[0007] (2) Technical solution

[0008] A first aspect of the present invention provides a method for detecting wire shortage in a composite material wire laying machine, comprising the following steps:

[0009] Based on the tow transmission and the actuator of the wire placement head, the logical relationship between the tow shortage and the state variables in the automatic placement control is established;

[0010] Collect the real-time state variables of the tow during automatic placement;

[0011] According to the real-time state variable and in combination with the logical relationship, it is determined whether the yarn bundle is missing.

[0012] Furthermore, the state variables include a feed servo axis position difference, a shielding state position, a tow usage position, a tow cutting position, a tow remainder difference and a tension detection position.

[0013] Furthermore, the logical relationship is specifically: when the following conditions are met at the same time, it is determined that the tow is missing:

[0014] The mask status bit is unmasked, F shield =0;

[0015] The tow usage bit is the tow used in the current strip, F using =1;

[0016] The tow cutting position is in a non-cutting state, F cut =0;

[0017] The tension detection position is when the tow tension is in normal state, F tension =0;

[0018] The difference in the remaining amount of the tow ΔL and the difference in the position of the feeding servo axis ΔW pos The absolute value of the difference is greater than the set threshold.

[0019] Furthermore, the position difference ΔW of the feeding servo axis pos Enter the servo axis position value W for the current sampling period pos (n) and the axis position value W sent in the previous sampling cycle pos The difference of (n-1).

[0020] Furthermore, the tow remainder difference ΔL is positively correlated with the tow encoder count value P(n) in the current sampling period and the diameter of the tow tensioning wheel.

[0021] Furthermore, the tow remainder difference ΔL is inversely correlated with the encoder resolution.

[0022] Furthermore, the real-time state variables of the tow during the automatic placement are collected, specifically:

[0023] The real-time state variables of the tow during the automatic placement process are collected through the control system.

[0024] Furthermore, when it is determined that a wire bundle is missing, the laying layer number and the strip number of the missing wire detection are mapped to the numerical control system, and the variable interaction of the automatic wire filling control is realized by jumping the determination of the laying layer number and the strip number.

[0025] The second aspect of the present invention provides a composite material wire laying machine wire shortage detection device based on the above-mentioned composite material wire laying machine wire shortage detection method, including a material reel, a tensioning shaft, a fixed shaft, an elastic support, a rocker arm, a recovery shaft and a control system, the moving wire bundle passes through the material reel, the fixed shaft and the tensioning shaft in sequence, the material reel is used to support the composite material wire bundle roll, and the recovery shaft is used to recover the wire bundle backing paper; the tensioning shaft is used to apply and buffer the tensioning force of the wire bundle, and drives the wire bundle to perform a circular motion with the fixed end of the rocker arm as the center of the circle, the elastic support member is used to elastically support the rocker arm, and the tensioning shaft is provided with an angle encoder for calculating the use length of the wire bundle; the control system is used to collect real-time state variables of the wire bundle during automatic placement.

[0026] Furthermore, the composite material wire laying machine wire shortage detection device also includes a first detection switch and a second detection switch, the first detection switch is used to detect whether the wire bundle tension is greater than a first preset value, and the second detection switch is used to detect whether the wire bundle tension is less than a second preset value; wherein the first preset value is greater than the second preset value.

[0027] (3) Beneficial effects

[0028] In summary, the present invention, based on the characteristics of the laying mechanisms of machine tool-type and robot-type wire laying machines, aims at the wire bundle quality defects such as missing wires that may occur during automatic laying, establishes a multivariable logical control relationship for wire bundle status detection, and calculates and detects the wire bundle status in real time, thereby improving the intelligent monitoring of the automatic wire laying machine and enhancing the laying quality detection and laying efficiency of the composite materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments of the present invention are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0030] Figure 1 It is a schematic flow chart of a method for detecting wire shortage in a composite material wire laying machine provided by an embodiment of the present invention;

[0031] Figure 2 It is a structural schematic diagram of a wire missing detection device for a composite material wire laying machine provided in an embodiment of the present invention.

[0032] In the figure:

[0033] 1- material reel; 2- tensioning shaft; 3- fixed shaft; 4- elastic support member; 5- rocker arm; 6- recovery shaft; 7- first detection switch; 8- second detection switch. DETAILED DESCRIPTION

[0034] The following detailed description of the embodiments of the present invention is provided in conjunction with the accompanying drawings and examples. The following detailed description of the embodiments and the accompanying drawings are used to illustrate the principles of the present invention, but cannot be used to limit the scope of the present invention, that is, the present invention is not limited to the described embodiments.

[0035] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present application will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0036] In the description of the present invention, it should be understood that the terms "upper", "lower", "front", "rear", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, or are the orientations or positional relationships in which the products of the present invention are conventionally placed when in use, or are the orientations or positional relationships conventionally understood by those skilled in the art. These are merely for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0037] Figure 1 FIG. 1 is a flow chart of a method for detecting wire shortage in a composite material wire laying machine provided by an embodiment of the present invention. Figure 1 , the method may include the following steps:

[0038] S100: Based on the tow transmission and the wire placement head actuator, a logical relationship between the wire shortage of the tow and the state variables in the automatic placement control is established.

[0039] S200, collecting real-time state variables of the tow during the automatic placement process.

[0040] S300, judging whether the yarn bundle is missing according to the real-time state variables and the logical relationship.

[0041] In the above embodiment, the state variables include the feed servo axis position difference, the shielding state bit, the tow usage bit, the tow cutting bit, the tow remainder difference and the tension detection bit.

[0042] Among them, W pos —The position value of the feeding servo shaft. The feeding servo shaft motor drives the tow feeding roller through the belt. The position value of the feeding servo shaft is the theoretical laying length of the tow. pos The acquisition is done by converting the NC system NC variables into PLC variables through the NC variable selector.

[0043] F shield —Shielding status position: when the tow is shielded, the tow does not participate in automatic placement, and the tow cutting position F cutSet to 1 (TURE). The tow shielding bit is selected and set in the host computer, and data is exchanged between the host computer and the PLC unit of the CNC system.

[0044] F using —Tow usage bit, by parsing the placement process file, the tow usage bit and tow length of each layer and strip in the executed placement program are stored in the cache variable array for real-time data collection and interaction.

[0045] F cut —Tow cutting position, the tow cutting control is to store the path position where the tow needs to be reduced by the pre-planned parameter variables (the position value W of the servo axis is fed into the pos ), the path position signal triggers the signal of the tow cutting valve island to complete the tow cutting control.

[0046] L—Tow remainder, which is used to calculate the tow remainder value through the A / B direction pulse encoder coaxially installed at the tail of the tow tensioning shaft. The tow remainder value is calculated in real time through the PLC program.

[0047] F tension —Tension detection position: the tension of the tow is determined by the tension detection switch to determine whether there is abnormal tension on the tensioning shaft. The tension detection position F of the tow is collected by PLC tension Delay signal, when F tension When the delay signal is 0 (FALSE), it indicates that the tow tension is in normal state.

[0048] As an optional implementation, the specific logical relationship is: when the following conditions are met at the same time, it is determined that the tow is missing:

[0049] The mask status bit is unmasked, F shield =0;

[0050] The tow usage position is the tow used in the current strip, F using =1;

[0051] The tow cutting position is in the non-cutting state, F cut =0;

[0052] The tension detection position is that the tow tension is in normal state, F tension =0;

[0053] Tow excess difference ΔL and feed servo axis position difference ΔW pos The absolute value of the difference is greater than the set threshold.

[0054] As shown in Table 1 below, for each tow, a logical relationship table of variables related to the tow missing detection of the automatic tow placing machine is established:

[0055] Table 1

[0056] Variables related to missing wire detection Variable Types Collection method Sampling period Correlation value <![CDATA[Feed servo axis position value W pos > Analog NC—PLC 100ms <![CDATA[Feed shaft position difference ΔW pos >0]]> <![CDATA[Shield status bit F shield > Digital quantity Host computer—PLC 100ms <![CDATA[F shield =0]]> <![CDATA[Fibril usage position F using > Digital quantity Host computer—PLC 100ms <![CDATA[F using =1]]> <![CDATA[Fiber bundle cutting position F cut > Digital quantity NC—PLC 100ms <![CDATA[F cut =0]]> Tow excess value L Analog PLC 100ms <![CDATA[|ΔL-ΔW pos |]]> <![CDATA[Tension detection position F tension > Digital quantity PLC 100ms <![CDATA[F tension =0]]>

[0057] It should be noted here that the feed servo axis position difference ΔW in Table 1 pos Enter the servo axis position value W for the current sampling period pos (n) and the axis position value W sent in the previous sampling cycle pos The difference of (n-1).

[0058] As an optional implementation, the tow remainder difference ΔL is positively correlated with the tow encoder count value P(n) of the current sampling period and the diameter of the tow tensioning wheel, and the tow remainder difference ΔL is negatively correlated with the encoder resolution. The tow remainder difference ΔL is calculated based on the count increment value ΔP of each tow pulse encoder, the encoder resolution K, and the tow tensioning wheel diameter d.

[0059] ΔP=P(n)-P(n-1);

[0060]

[0061] Where P(n) is the tow encoder count value of the current sampling period, and P(n-1) is the tow encoder count value of the previous sampling period.

[0062] During the feeding control of the tow, the tow remaining difference ΔL and the feeding servo axis position difference ΔW are compared in real time. pos The absolute value V = |ΔL-ΔW POS |>L th , L th To set the threshold.

[0063] When V>L th , the system will prompt a wire shortage alarm if the quality defect of wire shortage occurs.

[0064] As an optional implementation, when it is determined that a wire bundle is missing, the laying layer number and strip number of the missing wire detection are mapped to the CNC system, and the variable interaction of the automatic wire filling control is realized by jumping the laying layer number and strip number. The upper computer of the equipment collects the laying program, the position information of the servo axis, the R parameter and other variables through PLC and NC data. The layer number and strip number of the missing wire detection in the laying program are mapped to the R parameter of the CNC system, and the variable interaction of the automatic wire filling control is realized by jumping the laying layer number and strip number. The operation process of the composite material laying machine for automatic wire filling through the human-computer interaction interface.

[0065] Figure 2 is a structural schematic diagram of a composite material wire laying machine wire missing detection device provided by an embodiment of the present invention, see Figure 2The detection device may include a material reel 1, a tensioning shaft 2, a fixed shaft 3, an elastic support member 4, a swing rod 5, a recovery shaft 6 and a control system (not shown in the figure). The traveling tow passes through the material reel 1, the fixed shaft 2 and the tensioning shaft 3 in sequence. The material reel 1 is used to support the composite material tow roll, and the recovery shaft 2 is used to recover the tow lining paper; the tensioning shaft 3 is used to apply and buffer the tensioning force of the tow, and drives the tow to perform a circular motion with the fixed end of the swing rod 5 as the center of the circle. The elastic support member 4 is used to elastically support the swing rod 5. The tensioning shaft 3 is provided with an angle encoder for calculating the use length of the tow; the control system is used to collect the real-time state variables of the tow during the automatic placement process.

[0066] In the above embodiment, the material reel 1 is responsible for supporting the composite material tow roll, and adopts an air expansion shaft structure; the recovery shaft 6 is responsible for the recovery of the tow lining paper, and the end face is equipped with an easily removable baffle mechanism; the tensioning shaft 2 is responsible for applying and buffering the tensioning force of the tow, and can move up and down driven by the tow, and the elastic support member 4 can specifically adopt a reset spring, and the spring can be used to reset the tensioning shaft 2. The dynamic torque balance equation of the tow feeding, lining stripping, and tensioning mechanism is:

[0067]

[0068] Where, T 1 is the wire feeding tension, T 2 is the yarn tension, α 1 is the angle between the wire feeding direction and the tangent direction, α 2 is the angle between the wire-out direction and the tangent direction, α 3 is the angle between the return spring and the vertical line of the pendulum, J is the moment of inertia of the pendulum, ω(t) is the angular velocity of the pendulum, F s is the force of the return spring, M f is the friction torque, m is the weight of the swing arm, l b is the length of the pendulum, l s is the force arm of the spring, l m is the force arm of the swing arm's center of gravity, and r is the radius of the tensioning shaft. During the tow feeding and lining stripping process, the tensioning shaft 3 maintains dynamic balance according to the above formula and swings near the equilibrium position.

[0069] The tensioning shaft 3 is a free-rotating shaft equipped with an angle encoder (specifically, it can be an A / B phase pulse encoder) to calculate the use length of the tow. Its working principle is that for every rotation of the encoder shaft, phase A and phase B send out the same number of pulses, but there is a 90° phase difference between phase A and phase B. The forward and reverse direction of the encoder rotation can be determined based on the phase difference. When rotating forward, phase A leads phase B by 90° in phase output; when rotating reversely, phase B leads phase A by 90° in phase output. When there is no A signal and the B signal triggers the rising edge, the pulse count is -1; when there is no A signal and the B signal triggers the falling edge, the pulse count is +1. When the pulse count value exceeds the maximum value of the integer data 32767, the counter value returns to 0 to start counting.

[0070] As an optional implementation, Figure 2 As shown, the composite material laying machine wire shortage detection device also includes a first detection switch 7 and a second detection switch 8. The first detection switch 7 is used to detect whether the wire bundle tension is greater than a first preset value, and the second detection switch 8 is used to detect whether the wire bundle tension is less than a second preset value; wherein the first preset value is greater than the second preset value. The first detection switch 7 and the second detection switch 8 can monitor the wire bundle tension in real time to avoid the occurrence of faults that are difficult to detect.

[0071] It should be clear that the various embodiments in this specification are described in a progressive manner, and the same or similar parts between the various embodiments can be referred to each other, and each embodiment focuses on the differences from other embodiments. The present invention is not limited to the specific steps and structures described above and shown in the figures. In addition, for the sake of brevity, a detailed description of known methods and technologies is omitted here.

[0072] The above are only embodiments of the present application and are not limited to the present application. For those skilled in the art, the present application may have various changes and variations without departing from the scope of the present invention. Any modification, equivalent substitution, improvement, etc. made within the spirit and principle of the present application should be included in the scope of the claims of the present application.

Claims

1. A method for detecting missing wires in a composite material laying machine, characterized in that: The method comprises the following steps: Based on the tow transmission and the actuator of the wire placement head, the logical relationship between the tow shortage and the state variables in the automatic placement control is established; Collect the real-time state variables of the tow during automatic placement; According to the real-time state variable and in combination with the logical relationship, it is determined whether the yarn bundle is missing.

2. The method for detecting missing wires in a composite material laying machine according to claim 1, characterized in that: The state variables include a feed servo axis position difference, a shielding state position, a tow usage position, a tow cutting position, a tow remainder difference and a tension detection position.

3. The method for detecting missing wires in a composite material laying machine according to claim 2, characterized in that: The logical relationship is specifically: when the following conditions are met at the same time, it is determined that the tow is missing: The mask status bit is unmasked, F shield =0; The tow usage bit is the tow used in the current strip, F using =1; The tow cutting position is in a non-cutting state, F cut =0; The tension detection position is when the tow tension is in normal state, F tension =0; The difference in the remaining amount of the tow ΔL and the difference in the position of the feeding servo axis ΔW pos The absolute value of the difference is greater than the set threshold.

4. The method for detecting missing wires in a composite material wire laying machine according to claim 3, characterized in that: The feed servo axis position difference ΔW pos Enter the servo axis position value W for the current sampling period pos (n) and the axis position value W sent in the previous sampling cycle pos The difference of (n-1).

5. The method for detecting missing wires in a composite material laying machine according to claim 3, characterized in that: The tow remainder difference ΔL is positively correlated with the tow encoder count value P(n) of the current sampling period and the diameter of the tow tensioning wheel.

6. The method for detecting missing wires in a composite material laying machine according to claim 5, characterized in that: The tow remainder difference ΔL is inversely correlated with the encoder resolution.

7. The method for detecting missing wires in a composite material laying machine according to claim 1, characterized in that: The real-time state variables of the tow during the automatic placement process are collected, specifically: The real-time state variables of the tow during the automatic placement process are collected through the control system.

8. The method for detecting missing wires in a composite material laying machine according to claim 1, characterized in that: When it is determined that a wire bundle is missing, the laying layer number and the strip number of the wire missing detection are mapped to the numerical control system, and the variable interaction of the automatic wire filling control is realized by jumping the judgment of the laying layer number and the strip number.

9. A composite material wire laying machine wire missing detection device based on the composite material wire laying machine wire missing detection method according to any one of claims 1 to 8, characterized in that: The invention comprises a material reel (1), a tensioning shaft (2), a fixed shaft (3), an elastic support member (4), a swing rod (5), a recovery shaft (6) and a control system. The traveling tow passes through the material reel (1), the fixed shaft (2) and the tensioning shaft (3) in sequence. The material reel (1) is used to support the composite tow roll, and the recovery shaft (2) is used to recover the tow backing paper. The tensioning shaft (3) is used to apply and buffer the tensioning force of the tow and, driven by the tow, performs a circular motion with the fixed end of the swing rod (5) as the center. The elastic support member (4) is used to elastically support the swing rod (5). The tensioning shaft (3) is provided with an angle encoder for calculating the use length of the tow. The control system is used to collect the real-time state variables of the tow during the automatic placement process.

10. The composite material wire laying machine wire missing detection device according to claim 9, characterized in that: It also includes a first detection switch (7) and a second detection switch (8), wherein the first detection switch (7) is used to detect whether the tension of the yarn bundle is greater than a first preset value, and the second detection switch (8) is used to detect whether the tension of the yarn bundle is less than a second preset value; wherein the first preset value is greater than the second preset value.

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