A method for automatic tows placement of prepreg suitable for short strip placement

Abstract

The application discloses a kind of pre-impregnated tow automatic fiber placement methods suitable for short strip laying, belong to the technical field of composite automatic placement, by studying the minimum laying length of tow and the relationship between flexible compression roller deformation and end effector front inclination angle, a method suitable for short strip laying is proposed, which shortens the minimum laying length of tow of fiber placement machine, improves the process adaptability of fiber placement head, and can effectively reduce the area of laying compensation area, effectively save tow raw materials;At the same time, based on the way of laying tow by tilting end effector, based on the allowed deformation of flexible compression roller, the tilt angle of end effector is used to calculate the lag compensation distance of laying tow, and the tow is laid based on the lag compensation distance, to solve the problem of low laying precision of tow caused by tilting angle laying.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of automatic laying of composite materials, and particularly relates to a pre-impregnated tow automatic laying method suitable for short strip laying. BACKGROUND

[0002] The automatic tow laying technology is a composite material automatic forming manufacturing technology in which a plurality of pre-impregnated tows with a certain width from a creel are independently fed and cut by a laying head in an end effector, bundled into a pre-impregnated strip with adjustable width under a flexible compression roller, laid on a mold surface heated by a heating system according to a predetermined laying track, and compacted and shaped.

[0003] The composite material has strong designability, and a product is designed with a large number of local reinforcements, lost layers and openings. Due to the minimum laying length constraint of the tow laying machine, it is difficult to meet the process requirements at the corner position of each layer boundary and the position of adjacent two openings, the actual laid strip (formed by a plurality of pre-impregnated tows) has a length longer than the design requirement of the product, and there is a large area of process addition area, and there is a risk of interference with other parts in subsequent assembly.

[0004] In the prior art, the minimum laying length of the tow laying machine depends on the distance from the tow cutting point of the end effector to the tool center point. Since the automatic tow laying end effector is a multifunctional integrated compact mechanism, the distance from the cutting point to the tool center point of the existing tow laying machine has been designed to be short enough, and it is difficult to further improve, it is difficult to further shorten the minimum laying length of the pre-impregnated tow by optimizing the design of the end effector, and it is difficult to meet the laying requirement of the short strip of the composite product.

[0005] Therefore, in view of the problem of large process addition area length and waste of laying material in the existing composite material tow laying forming process, the application discloses a pre-impregnated tow automatic laying method suitable for short strip laying. SUMMARY

[0006] The application discloses a pre-impregnated tow automatic laying method suitable for short strip laying, which can effectively reduce the minimum laying length, reduce the process addition area, and further ensure the composite material tow laying forming quality while reducing the waste of tows.

[0007] The application is achieved by the following technical scheme:

[0008] An automatic fiber placement method for short strip laying is provided, which adopts an end-of-arm tooling with a flexible roller to place the fiber tows, calculates the minimum vertical pressure laying length of the end-of-arm tooling when placing the fiber tows vertically, and calculates the minimum forward laying length of the end-of-arm tooling when placing the fiber tows forwardly; if the actual required laying length of the fiber tows is greater than or equal to the minimum vertical pressure laying length, the end-of-arm tooling is used to place the fiber tows vertically; if the actual required laying length of the fiber tows is less than the minimum vertical pressure laying length, the end-of-arm tooling is used to place the fiber tows forwardly, and the actual required laying length of the fiber tows is compared with the minimum forward laying length; during the forward laying of the fiber tows, if the actual required laying length of the fiber tows is greater than or equal to the minimum forward laying length, the lag compensation distance of the fiber tows is calculated based on the allowable deformation of the flexible roller and the forward angle of the end-of-arm tooling, and the fiber tows are placed based on the lag compensation distance; if the actual required laying length of the fiber tows is less than the minimum forward laying length, a laying compensation area is added along the laying direction of the fiber tows, and then the lag compensation distance of the fiber tows is calculated based on the allowable deformation of the flexible roller and the forward angle of the end-of-arm tooling, and the fiber tows are placed based on the lag compensation distance.

[0009] In order to better realize the present application, further, the following steps are specifically included:

[0010] Step 1, obtaining the intersection Q of the telescopic axis of the end-of-arm tooling and the outer edge of the flexible roller, calculating the fiber tow length between the fiber tow cutting point and the intersection Q, and obtaining the radius of the flexible roller;

[0011] Step 2, obtaining the allowable deformation of the flexible roller in the fiber laying area, and obtaining the maximum allowable inclination angle of the end-of-arm tooling when laying the fiber tows forwardly;

[0012] Step 3, calculating the minimum vertical pressure laying length of the end-of-arm tooling when laying the fiber tows vertically based on the allowable deformation of the flexible roller in the fiber laying area, and calculating the minimum forward laying length of the end-of-arm tooling when laying the fiber tows forwardly based on the allowable deformation of the flexible roller in the fiber laying area and the maximum allowable inclination angle of the end-of-arm tooling when laying the fiber tows forwardly;

[0013] Step 4, if the actual required laying length of the fiber tows is greater than or equal to the minimum vertical pressure laying length, the end-of-arm tooling is directly used to lay the fiber tows vertically; if the actual required laying length of the fiber tows is less than the minimum vertical pressure laying length, the end-of-arm tooling is used to lay the fiber tows forwardly, and the actual required laying length of the fiber tows is compared with the minimum forward laying length; if the actual required laying length of the fiber tows is greater than or equal to the minimum forward laying length, step 5 is entered; if the actual required laying length of the fiber tows is less than the minimum forward laying length, step 6 is entered;

[0014] Step 5: Calculate the hysteresis compensation distance for placing the tow based on the allowable deformation of the flexible pressure roller and the forward tilt angle of the end telescopic actuator, and perform placement compensation on the tow based on the hysteresis compensation distance;

[0015] Step 6: Add a placement supplement area along the laying direction of the tow, and then calculate the hysteresis compensation distance of the placed tow based on the allowable deformation of the flexible pressure roller and the tilt angle of the end telescopic actuator, and compensate the tow for placement based on the hysteresis compensation distance.

[0016] In order to better implement the present invention, further, in step 3, the formula for calculating the minimum forward-leaning placement length when the end telescopic actuator places the tow forward is as follows:

[0017] ;

[0018] in: Indicates the minimum forward lay length; It represents the length of the tow between the tow cutting point and the intersection point Q; R represents the radius of the flexible pressure roller; Indicates the laying allowance of the tow; Indicates the allowable deformation of the flexible pressure roller in the fiber placement area; Indicates the deformation inclination angle of the flexible pressure roller; It represents the maximum allowable inclination angle of the end telescopic actuator when it tilts forward to lay the tow; k represents the sign coefficient; 丨PQ丨 represents the distance between the intersection P of the telescopic axis of the end telescopic actuator and the mold surface and the intersection Q of the telescopic axis of the end telescopic actuator and the outer edge of the flexible pressure roller.

[0019] In order to better implement the present invention, further, in step 3, the formula for calculating the minimum vertical pressure placement length when the end telescopic actuator vertically places the tow is as follows:

[0020] ;

[0021] in: Indicates the minimum vertical pressure laying length; It represents the length of the tow between the tow cutting point and the intersection point Q; R represents the radius of the flexible pressure roller; Indicates the laying allowance of the tow; Indicates the allowable deformation of the flexible pressure roller in the fiber placement area; represents the deformation inclination angle of the flexible pressure roller; k represents the sign coefficient; 丨PQ丨 represents the distance between the intersection point P of the telescopic axis of the end telescopic actuator and the mold surface and the intersection point Q of the telescopic axis of the end telescopic actuator and the outer edge of the flexible pressure roller.

[0022] In order to better realize the present invention, further, if Less than or equal to If the value of the symbol coefficient k is 1, then the value of the symbol coefficient k is 1; if the value of the symbol coefficient k is 0, then the value of the symbol coefficient k is 0; if the value of the symbol coefficient k is -1, then the value of the symbol coefficient k is -1. If the value of the symbol coefficient k is 1, then the value of the symbol coefficient k is 1; if the value of the symbol coefficient k is 0, then the value of the symbol coefficient k is 0; if the value of the symbol coefficient k is -1, then the value of the symbol coefficient k is -1. If the value of the symbol coefficient k is 1, then the value of the symbol coefficient k is 1; if the value of the symbol coefficient k is 0, then the value of the symbol coefficient k is 0; if the value of the symbol coefficient k is -1, then the value of the symbol coefficient k is -1.

[0023] In order to better realize the present application, further, the laying allowance is greater than or equal to 5mm.

[0024] In order to better realize the present application, further, in step 5, the step of calculating the lag compensation distance is as follows:

[0025] Step A1, calculating the vertical pressure wire length between the cutting point of the wire and the intersection point P in the vertical pressure laying state of the end stretching and retracting actuator;

[0026] Step A2, calculating the forward tilting wire length between the cutting point of the wire and the intersection point P in the forward tilting laying state of the end stretching and retracting actuator;

[0027] Step A3, calculating the difference between the vertical pressure wire length and the forward tilting wire length as the lag compensation distance;

[0028] Step A4, based on the lag compensation distance, sending the wire laying control instruction to the wire laying control system in the forward tilting laying state of the end stretching and retracting actuator.

[0029] In order to better realize the present application, further, in step 5, the formula for calculating the lag compensation distance is as follows:

[0030]

[0031]

[0032] ;

[0033] Wherein: represents the lag compensation distance; s1 represents the vertical pressure wire length between the cutting point of the wire and the intersection point P in the vertical pressure laying state of the end stretching and retracting actuator; s2 represents the forward tilting wire length between the cutting point of the wire and the intersection point P in the forward tilting laying state of the end stretching and retracting actuator; L0 represents the wire length between the cutting point of the wire and the intersection point Q; R represents the radius of the flexible compression roller; represents the allowable deformation amount of the flexible compression roller in the wire laying area; represents the deformation inclination angle of the flexible compression roller; represents the maximum allowable inclination angle in the forward tilting laying state of the end stretching and retracting actuator.

[0034] In order to better realize the present application, further, the laying supplement area can completely cover the product laying boundary in the laying direction.

[0035] Compared with the prior art, the present application has the following advantages and beneficial effects:

[0036] The present application shortens the minimum laying length of the tows of the tow laying machine, improves the process adaptability of the tow laying head, and effectively reduces the area of the laying compensation area and effectively saves the tow raw materials. Meanwhile, based on the tow laying method of the end-of-arm manipulator, the present application calculates the lag compensation distance of the laid tow based on the allowable deformation of the flexible compression roller and the inclination angle of the end-of-arm manipulator, and compensates the tow based on the lag compensation distance, thereby solving the problem of low tow laying precision caused by the inclination angle laying. BRIEF DESCRIPTION OF DRAWINGS

[0037] Figure 1 Flowchart of the automatic tow laying method suitable for short strip laying;

[0038] Figure 2 Schematic diagram of adding a laying compensation area at the position of the layer boundary corner;

[0039] Figure 3 Schematic diagram of adding a laying compensation area at the position of the opening;

[0040] Figure 4 Schematic diagram of the end-of-arm manipulator vertically laying the tow;

[0041] Figure 5 Schematic diagram of the end-of-arm manipulator laying the tow at a first inclination angle;

[0042] Figure 6 Schematic diagram of the end-of-arm manipulator laying the tow at a second inclination angle. DETAILED DESCRIPTION

[0043] Example 1:

[0044] The automatic fiber placement method for short strip laying of the embodiment is suitable for short strip laying, adopts the end-of-arm tooling with flexible pressure roller to place the fiber tow, calculates the minimum vertical pressure placement length of the end-of-arm tooling when placing the fiber tow vertically, and calculates the minimum forward placement length of the end-of-arm tooling when placing the fiber tow forwardly; if the actual required placement length of the fiber tow is greater than or equal to the minimum vertical pressure placement length, the end-of-arm tooling is used to place the fiber tow vertically; if the actual required placement length of the fiber tow is less than the minimum vertical pressure placement length, the end-of-arm tooling is used to place the fiber tow forwardly, and the actual required placement length of the fiber tow is compared with the minimum forward placement length; during the forward placement of the fiber tow, if the actual required placement length of the fiber tow is greater than or equal to the minimum forward placement length, the lag compensation distance of the fiber tow is calculated based on the allowable deformation amount of the flexible pressure roller and the forward angle of the end-of-arm tooling, and the fiber tow is placed based on the lag compensation distance; if the actual required placement length of the fiber tow is less than the minimum forward placement length, a placement compensation area is added along the layer direction of the fiber tow, and then the lag compensation distance of the fiber tow is calculated based on the allowable deformation amount of the flexible pressure roller and the forward angle of the end-of-arm tooling, and the fiber tow is placed based on the lag compensation distance.

[0045] Specifically, the following steps are included:

[0046] Step 1, obtaining the intersection Q of the telescopic axis of the end-of-arm tooling and the outer edge of the flexible pressure roller, calculating the fiber tow length between the fiber tow cutting point and the intersection Q, and obtaining the radius of the flexible pressure roller;

[0047] Step 2, obtaining the allowable deformation amount of the flexible pressure roller in the fiber placement area, and obtaining the maximum allowable inclination angle of the end-of-arm tooling when placing the fiber tow forwardly;

[0048] Step 3, calculating the minimum vertical pressure placement length of the end-of-arm tooling when placing the fiber tow vertically based on the allowable deformation amount of the flexible pressure roller in the fiber placement area, and calculating the minimum forward placement length of the end-of-arm tooling when placing the fiber tow forwardly based on the allowable deformation amount of the flexible pressure roller in the fiber placement area and the maximum allowable inclination angle of the end-of-arm tooling when placing the fiber tow forwardly;

[0049] Step 4, if the actual required placement length of the fiber tow is greater than or equal to the minimum vertical pressure placement length, the end-of-arm tooling is directly used to place the fiber tow vertically; if the actual required placement length of the fiber tow is less than the minimum vertical pressure placement length, the end-of-arm tooling is used to place the fiber tow forwardly, and the actual required placement length of the fiber tow is compared with the minimum forward placement length; if the actual required placement length of the fiber tow is greater than or equal to the minimum forward placement length, step 5 is entered; if the actual required placement length of the fiber tow is less than the minimum forward placement length, step 6 is entered;

[0050] Step 5, calculate the hysteresis compensation distance of the laying fiber based on the allowable deformation of the flexible compression roller, the front inclination angle of the end telescopic actuator, and compensate the laying fiber based on the hysteresis compensation distance;

[0051] Step 6, increase the laying compensation area along the laying direction of the fiber, and calculate the hysteresis compensation distance of the laying fiber based on the allowable deformation of the flexible compression roller and the front inclination angle of the end telescopic actuator, and compensate the laying fiber based on the hysteresis compensation distance.

[0052] In step 3, the formula for calculating the minimum front inclination laying length of the end telescopic actuator is as follows:

[0053] ;

[0054] Wherein: represents the minimum front inclination laying length; represents the fiber length between the fiber cutting point and the intersection point Q; R represents the radius of the flexible compression roller; represents the laying allowance of the fiber; represents the allowable deformation of the flexible compression roller in the fiber laying area; represents the deformation inclination angle of the flexible compression roller; represents the maximum allowable inclination angle of the end telescopic actuator when laying the fiber; k represents the symbol coefficient; represents the distance between the intersection point P of the telescopic axis of the end telescopic actuator and the mold surface and the intersection point Q of the telescopic axis of the end telescopic actuator and the outer edge of the flexible compression roller.

[0055] In step 3, the formula for calculating the minimum vertical laying length of the end telescopic actuator is as follows:

[0056] ;

[0057] Wherein: represents the minimum vertical laying length; represents the fiber length between the fiber cutting point and the intersection point Q; R represents the radius of the flexible compression roller; represents the laying allowance of the fiber; represents the allowable deformation of the flexible compression roller in the fiber laying area; represents the deformation inclination angle of the flexible compression roller; k represents the symbol coefficient; represents the distance between the intersection point P of the telescopic axis of the end telescopic actuator and the mold surface and the intersection point Q of the telescopic axis of the end telescopic actuator and the outer edge of the flexible compression roller.

[0058] Further, if is less than or equal to , the symbol coefficient k is 1; if is greater than The sign coefficient k takes the value -1.

[0059] Further, the laying allowance is greater than or equal to 5mm.

[0060] Further, in step 5, the step of calculating the hysteresis compensation distance is as follows:

[0061] Step A1, calculating the vertical pressure filament length between the cutting point of the filament and the intersection point P in the vertical pressure laying state of the end-of-arm manipulator;

[0062] Step A2, calculating the forward tilting filament length between the cutting point of the filament and the intersection point P in the forward tilting laying state of the end-of-arm manipulator;

[0063] Step A3, calculating the difference between the vertical pressure filament length and the forward tilting filament length as the hysteresis compensation distance;

[0064] Step A4, based on the hysteresis compensation distance, sending the filament laying control instruction to the filament laying control system in the forward tilting laying state of the end-of-arm manipulator.

[0065] In step 5, the formula for calculating the hysteresis compensation distance is as follows:

[0066]

[0067] ;

[0068] Wherein: represents the hysteresis compensation distance; s1 represents the vertical pressure filament length between the cutting point of the filament and the intersection point P in the vertical pressure laying state of the end-of-arm manipulator; s2 represents the forward tilting filament length between the cutting point of the filament and the intersection point P in the forward tilting laying state of the end-of-arm manipulator; L0 represents the filament length between the cutting point of the filament and the intersection point Q; R represents the radius of the flexible compression roller; represents the allowable deformation amount of the flexible compression roller in the filament laying area; represents the deformation inclination angle of the flexible compression roller; represents the maximum allowable inclination angle in the forward tilting laying state of the end-of-arm manipulator.

[0069] Further, as shown in Figure 2 and Figure 3 The laying compensation area ensures that the product laying boundary can be completely covered along the laying direction.

[0070] Further, as shown in Figure 4As shown in the figure, the end effector applies vertical pressure to lay the tow, that is, the telescopic axis of the end effector is perpendicular to the laying surface to lay the tow. When laying the tow, the flexible pressure roller is compressed by the end effector, and the floating direction of the end effector is always consistent with the direction of the mold normal vector. The deformation of the flexible pressure roller is recorded as . Driven by the upstream feed motor, the filament bundle is gradually fed from the cutting point A to the bottom of the flexible pressure roller along the filament bundle channel on the end effector. The angle between the filament bundle channel and the telescopic direction of the end effector is a fixed value, and the angle does not change with the change of the end effector posture. Point B is the tangent point between the filament bundle and the outer edge of the flexible pressure roller, and point F is the starting point where the filament bundle is initially compacted on the mold surface by the flexible pressure roller. After the filament bundle passes point F, the feeding mechanism stops feeding and performs the cutting operation. Point Q is the intersection of the telescopic axis of the end telescopic actuator and the outer edge of the flexible pressure roller. The filament bundle upstream of the cutting point A stops in the end effector under the action of the yarn stopping mechanism, and the filament bundle downstream of the cutting point A lays the cut filament bundle on the mold surface under the action of the flexible pressure roller. At this time, the length of the filament bundle laid on the mold surface is the minimum vertical pressure laying length. Therefore, the minimum vertical pressure laying length It can be expressed as:

[0071] ;

[0072] in: Tow cutting point The distance to the intersection Q of the telescopic axis of the end telescopic actuator and the outer edge of the flexible pressure roller is obviously It is only related to the end effector structure and is a fixed value; It represents the straight-line distance between the cutting point A and the tangent point B between the tow and the outer edge of the flexible pressure roller; It represents the length of the arc between the tangent point B between the filament bundle and the outer edge of the flexible pressing roller and the starting point F where the filament bundle is initially compacted by the flexible pressing roller on the mold surface; It represents the length of the arc between the starting point F where the tow is initially compacted by the flexible pressure roller on the mold surface and the intersection point Q of the telescopic axis of the end telescopic actuator and the outer edge of the flexible pressure roller; Indicates the tow laying allowance.

[0073] Example 2:

[0074] This embodiment is further optimized based on embodiment 1. Figure 5 As shown, the tow length L0 between the tow cutting point A and the intersection point Q is 90 mm, the radius R of the flexible roller is 35 mm, and the allowable deformation in the laying area is The maximum allowable inclination angle when the end telescopic actuator is tilted forward to place the tow is 3mm is 10°.

[0075] The maximum allowable inclination angle is 0°, and the allowable deformation amount of the flexible compression roller is substituted into the following formula:

[0076] ;

[0077] wherein: represents the minimum vertical compression laying length; represents the length of the fiber between the cutting point of the fiber and the intersection point Q; and R represents the radius of the flexible compression roller; represents the laying allowance of the fiber; represents the allowable deformation amount of the flexible compression roller in the fiber laying area; represents the deformation inclination angle of the flexible compression roller; k represents a symbol coefficient; and |PQ| represents the distance between the intersection point P of the extension axis of the end extension actuator and the mold surface and the intersection point Q of the extension axis of the end extension actuator and the outer edge of the flexible compression roller.

[0078] The minimum vertical compression laying length of the end extension actuator when laying the fiber by vertical compression is obtained as 80.40 mm. When the actual required laying length of the fiber, denoted as L x , is less than 80.40 mm, the fiber laying by the end extension actuator by vertical compression cannot be completed, and a process supplement area needs to be added.

[0079] The allowable deformation amount of the flexible compression roller and the maximum allowable inclination angle = 10° are substituted into the following formula:

[0080] ;

[0081] wherein: represents the minimum forward inclination laying length; represents the length of the fiber between the cutting point of the fiber and the intersection point Q; and R represents the radius of the flexible compression roller; represents the laying allowance of the fiber; represents the allowable deformation amount of the flexible compression roller in the fiber laying area; represents the deformation inclination angle of the flexible compression roller; represents the maximum allowable inclination angle of the end extension actuator when laying the fiber by forward inclination; k represents a symbol coefficient; and |PQ| represents the distance between the intersection point P of the extension axis of the end extension actuator and the mold surface and the intersection point Q of the extension axis of the end extension actuator and the outer edge of the flexible compression roller.

[0082] The minimum forward inclination laying length L of the end extension actuator when laying the fiber by forward inclination is obtained as 74.29 mm. x, when the length of the tow is greater than or equal to 74.29 mm, the strip can be laid directly by tilting the tow forward with the end telescopic actuator, without adding additional area. x When it is less than 74.29 mm, the strip placement cannot be completed directly by using the end telescopic actuator to lay the tow forward, and the process supplementary area needs to be increased. However, the area of ​​the supplementary area is smaller than that of the end telescopic actuator to lay the tow vertically.

[0083] get is 2.51mm, due to Greater than ,but Take -1, that is, by adjusting the pressure of the end effector to make the relative balance point extend by 2.5mm, at this time the deformation of the flexible pressure roller meets the requirements of offline programming setting.

[0084] The allowable deformation of the flexible pressure roller and maximum allowable inclination angle =10°Substitute into the following formula:

[0085]

[0086]

[0087] ;

[0088] Get lag distance It is 0.89mm, and the hysteresis compensation method is used for laying compensation.

[0089] The rest of this embodiment is the same as that of embodiment 1, so it will not be described again.

[0090] Example 3:

[0091] This embodiment is further optimized based on the above embodiment 1. Figure 6 As shown, the length of the tow between the tow cutting point A and the intersection point Q is L 0 is 90mm, the radius of the flexible roller R is 35mm, and the allowable deformation in the laying area The maximum allowable inclination angle when the end telescopic actuator is tilted forward to place the tow is 1.5mm is 20°.

[0092] When laying vertically, the maximum allowable inclination angle is 0°, and the allowable deformation of the flexible pressure roller is Substitute the following formula:

[0093] ;

[0094] in: Indicates the minimum vertical pressure laying length; It represents the length of the tow between the tow cutting point and the intersection point Q; R represents the radius of the flexible pressure roller; Indicates the laying allowance of the tow; Indicates the allowable deformation of the flexible pressure roller in the fiber placement area; represents the deformation inclination angle of the flexible pressure roller; k represents the sign coefficient; 丨PQ丨 represents the distance between the intersection point P of the telescopic axis of the end telescopic actuator and the mold surface and the intersection point Q of the telescopic axis of the end telescopic actuator and the outer edge of the flexible pressure roller.

[0095] Get the minimum down-lay length obtained when not using down-lay tow is 84.72 mm. When the actual laying length of the tow is L x When it is less than 80.40mm, it is impossible to use the end telescopic actuator to vertically press the tow to complete the laying of the strip, and an additional process area needs to be added.

[0096] The allowable deformation of the flexible pressure roller and maximum allowable inclination angle =20°Substitute into the following formula:

[0097] ;

[0098] in: Indicates the minimum forward lay length; It represents the length of the tow between the tow cutting point and the intersection point Q; R represents the radius of the flexible pressure roller; Indicates the laying allowance of the tow; Indicates the allowable deformation of the flexible pressure roller in the fiber placement area; Indicates the deformation inclination angle of the flexible pressure roller; It represents the maximum allowable inclination angle of the end telescopic actuator when it tilts forward to lay the tow; k represents the sign coefficient; 丨PQ丨 represents the distance between the intersection P of the telescopic axis of the end telescopic actuator and the mold surface and the intersection Q of the telescopic axis of the end telescopic actuator and the outer edge of the flexible pressure roller.

[0099] The minimum forward tilt placement length L obtained by using the end telescopic actuator to place the tow forward is 72.50 mm. x When the length of the tow is greater than or equal to 72.50 mm, the strip can be laid directly by tilting the tow forward with the end telescopic actuator, without adding additional area. x When it is less than 72.50mm, the strip placement cannot be completed directly by using the end telescopic actuator to lay the tow forward, and the process supplementary area needs to be increased. However, the area of ​​the supplementary area is smaller than that of the end telescopic actuator to lay the tow vertically.

[0100] get 0.65mm, less than or equal to , Take 1, i.e. adjust the pressure of the end effector to compress 0.65mm relative to the equilibrium point, at which time the flexible press roller deformation meets the offline programming set requirements.

[0101] The allowable deformation amount of the flexible press roller and the maximum allowable inclination angle = 20° are substituted into the following formula:

[0102]

[0103]

[0104] ;

[0105] The hysteresis distance is 0.17mm, and a hysteresis compensation method is used for laying compensation.

[0106] Other parts of the embodiment are the same as the above-described embodiment 1, and thus will not be described again.

[0107] The above is only a preferred embodiment of the present application, and does not limit the present application in any form. Any simple modification or equivalent change made according to the technical essence of the present application to the above embodiment falls within the protection scope of the present application.

Claims

1. A method for automatically placing prepreg tows suitable for short strip placement, characterized in that: The specific steps include: Step 1: Obtain the intersection point Q between the telescopic axis of the end telescopic actuator and the outer edge of the flexible pressure roller, calculate the length of the tow between the tow cutting point and the intersection point Q, and obtain the radius of the flexible pressure roller; Step 2: obtaining the allowable deformation of the flexible pressure roller in the fiber placement area and the maximum allowable inclination angle of the end telescopic actuator when tilting forward to place the fiber bundle; Step 3: Calculate the minimum vertical placement length of the end telescopic actuator when placing the tow vertically based on the allowable deformation of the flexible pressure roller in the placement area; calculate the minimum forward tilt placement length of the end telescopic actuator when placing the tow forward based on the allowable deformation of the flexible pressure roller in the placement area and the maximum allowable tilt angle when the end telescopic actuator is tilted forward; Step 4: If the actual required laying length of the tow is greater than or equal to the minimum vertical pressure laying length, the end telescopic actuator is directly used to lay the tow vertically; if the actual required laying length of the tow is less than the minimum vertical pressure laying length, the end telescopic actuator is used to lay the tow forward and compare the actual required laying length of the tow with the minimum forward laying length. If the actual required laying length of the tow is greater than or equal to the minimum forward laying length, proceed to step 5; if the actual required laying length of the tow is less than the minimum forward laying length, proceed to step 6. Step 5: Calculate the hysteresis compensation distance for placing the tow based on the allowable deformation of the flexible pressure roller and the forward tilt angle of the end telescopic actuator, and perform placement compensation on the tow based on the hysteresis compensation distance; Step 6: Add a placement supplement area along the laying direction of the tow, and then calculate the hysteresis compensation distance of the placed tow based on the allowable deformation of the flexible pressure roller and the tilt angle of the end telescopic actuator, and compensate the tow for placement based on the hysteresis compensation distance.

2. The automatic prepreg tow placement method for short strip placement according to claim 1, characterized in that: In step 3, the formula for calculating the minimum forward-tilted placement length when the end telescopic actuator tilts forward to place the tow is as follows: ； Wherein: represents the minimum forward laying length; represents the length of the fiber bundle between the fiber bundle cutting point and the intersection point Q; R represents the radius of the flexible pressure roller; represents the laying allowance of the fiber bundle; represents the allowable deformation of the flexible pressure roller in the fiber laying area; represents the deformation inclination angle of the flexible pressure roller; represents the maximum allowable inclination angle when the end telescopic actuator lays the fiber bundle forward; k represents the sign coefficient; 丨PQ丨 represents the distance between the intersection point P of the telescopic axis of the end telescopic actuator and the die surface and the intersection point Q of the telescopic axis of the end telescopic actuator and the outer edge of the flexible pressure roller.

3. The method for automatically placing prepreg tows suitable for short strip placement according to claim 2, characterized in that: In step 3, the formula for calculating the minimum vertical pressure placement length when the end telescopic actuator vertically places the tow is as follows: ； Wherein: represents the minimum vertical pressing and laying length; represents the length of the fiber bundle between the fiber bundle cutting point and the intersection point Q; R represents the radius of the flexible pressing roller; represents the laying allowance of the fiber bundle; represents the allowable deformation of the flexible pressing roller in the fiber laying area; represents the deformation inclination angle of the flexible pressing roller; k represents the sign coefficient; |PQ| represents the distance between the intersection point P of the telescopic axis of the end telescopic actuator and the die surface and the intersection point Q of the telescopic axis of the end telescopic actuator and the outer edge of the flexible pressing roller.

4. The method for automatically placing prepreg tows suitable for short strip placement according to claim 3, characterized in that: like Less than or equal to , then the symbol coefficient k takes the value 1; if Greater than , then the symbol coefficient k takes the value -1.

5. The method for automatically placing prepreg tows suitable for short strip placement according to claim 4, characterized in that: The paving margin is greater than or equal to 5 mm.

6. The method for automatically placing prepreg tows suitable for short strip placement according to claim 2, characterized in that: In step 5, the steps for calculating the hysteresis compensation distance are as follows: Step A1: Calculate the vertical pressure tow length between the cutting point of the tow and the intersection point P when the end telescopic actuator is in the vertical pressure placement state; Step A2: Calculate the forward-leaning tow length between the cutting point of the tow and the intersection point P when the end telescopic actuator is in a forward-leaning state to lay the tow; Step A3: Calculate the difference between the length of the vertically pressed tow and the length of the forwardly inclined tow as the hysteresis compensation distance; Step A4: When the end telescopic actuator is used to tilt forward to place the tow, a wire placement control instruction is sent to the wire placement control system with a delay based on the lag compensation distance.

7. The automatic prepreg tow placement method for short strip placement according to claim 6, characterized in that: In step 5, the formula for calculating the hysteresis compensation distance is as follows: ； in: Indicates the hysteresis compensation distance; s1 indicates the vertical pressure tow length between the cutting point and the intersection point P of the tow when the end telescopic actuator is used to vertically lay the tow; s2 indicates the forward tilted tow length between the cutting point and the intersection point P of the tow when the end telescopic actuator is used to tilt the tow; L0 indicates the tow length between the cutting point and the intersection point Q; R indicates the radius of the flexible pressure roller; Indicates the allowable deformation of the flexible pressure roller in the fiber placement area; Indicates the deformation inclination angle of the flexible pressure roller; Indicates the maximum allowable inclination angle of the end telescopic actuator when it tilts forward to place the tow.

8. The automatic prepreg tow placement method for short strip placement according to any one of claims 1 to 5, characterized in that: The laying additional area ensures that the product ply boundary can be completely covered along the ply direction.

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