A continuous fiber 3D printing corner speed reduction method based on corner curvature characteristics

Abstract

The application discloses a continuous fiber 3D printing corner speed reduction method based on a corner curvature feature, and comprises the following steps: obtaining a 3D printing model, and setting an advance speed reduction distance and a delay speed reduction distance; obtaining point density on a printing path in the 3D printing model, and performing density refinement processing on the printing path with a point density less than a critical density parameter; judging a path meeting a critical condition as a corner or a circular arc, and calculating an optimal printing speed corresponding to the corner path according to structure parameters of the corner or the circular arc and a previously obtained structure parameter and optimal printing speed relationship formula; and printing with advance and delay speed reduction. The application solves the problems of fiber twisting, fiber misplacement and fiber fracture caused by the existing 3D printing process, improves the bonding effect of the continuous fiber path corner, fully plays the effect of the continuous fiber reinforced composite material, improves the continuous fiber printing efficiency and quality, and further improves the mechanical properties of the whole fiber reinforced composite material component.

Description

Technical Field

[0001] The present invention belongs to the fields of material manufacturing and computer technology, relates to 3D printing technology, and specifically relates to a continuous fiber 3D printing corner speed reduction method based on corner curvature characteristics. Background Art

[0002] Fiber-reinforced composites (FRPs), with their advantages of high specific strength, high specific modulus, and corrosion resistance, play a crucial role in achieving lightweight, green, and high-performance manufacturing for high-end equipment. They are widely used in high-end manufacturing fields such as automotive and aerospace. Fiber-reinforced composites can be used to control the local mechanical properties of composite components through optimization methods such as layup design and trajectory planning.

[0003] Compared to traditional continuous fiber-reinforced composite manufacturing methods such as compression molding and winding, 3D printing, as an emerging manufacturing technology, offers advantages such as rapid fabrication of complex components, excellent controllability, and material savings, opening up the possibility of integrated molding of high-performance composite materials. The rapid development of 3D printing technology is expected to achieve low-cost production of high-performance composite materials, further expanding the application of composite materials. However, during continuous fiber 3D printing, defects may occur when the nozzle pulls the continuous fiber and redirects it.

[0004] In continuous fiber path turning scenarios, existing 3D printing processes often result in defects such as fiber distortion, fiber misalignment, and fiber breakage, further impacting the overall mechanical properties of fiber-reinforced composite components. Currently, a constant speed reduction approach (printing at a fixed, lower speed whenever a path deflection is encountered) is commonly used to address turning features in continuous fiber 3D printing paths, significantly impacting overall printing efficiency. Summary of the Invention

[0005] To solve the above problems, the present invention discloses a method for reducing the speed of continuous fiber 3D printing corners based on the corner curvature characteristics, so as to achieve high-precision and high-quality printing of continuous fibers at the path corners.

[0006] To achieve the above object, the technical solution of the present invention is as follows:

[0007] A method for reducing the speed of continuous fiber 3D printing corners based on corner curvature characteristics comprises the following steps:

[0008] Step 1: Obtain a 3D printed model and set the advance deceleration distance and the delayed deceleration distance;

[0009] Step 2: Obtain the point density on the printing path in the 3D printing model, make a judgment based on the preset critical density parameter, and perform density refinement on the printing path with a point density less than the critical density parameter;

[0010] Step 3, collecting the printing path data in the 3D printing model and performing critical condition judgment, judging the path meeting the critical condition as a corner or an arc, and calculating the optimal printing speed corresponding to the corner path according to the structure parameters of the corner or the arc and the previously obtained relationship between the structure parameters and the optimal printing speed;

[0011] The process of calculating the optimal printing speed corresponding to the corner path according to the structure parameters of the corner or the arc and the previously obtained relationship between the structure parameters and the optimal printing speed comprises:

[0012] The curvature value at the corner or the arc of the path is calculated, and the optimal printing speed is calculated through f(k, v), which is the corresponding relationship between the curvature value k and the optimal printing speed v established through multiple experiments;

[0013] Or

[0014] The chord length ratio of the corner / arc in the printing path is recorded, the maximum printable speed v1 and the minimum printable speed v2 are obtained through the chord length ratio and the speed corresponding relationship, the printing speed v3 of any point in the arc is calculated as (the degree of the point / π) x the maximum speed v1, and when the calculated printing speed v3 is less than the minimum speed v2, the minimum speed v2 is taken as the printing speed v; the chord length ratio and the speed corresponding relationship are the relationship f(m, v1, v2) between the maximum printable speed v1 and the minimum printable speed v2 corresponding to the chord length ratio m established through multiple experiments;

[0015] Step 4, the optimal printing speed is used to print at a distance n1 away from the corner, and the optimal printing speed is maintained until the original printing speed is restored at a distance n2 away from the corner.

[0016] Further, the density refinement processing in step 2 comprises: performing an insertion point operation in the printing path.

[0017] Further, the process of collecting the printing path data in the 3D printing model and performing critical condition judgment in step 3 comprises: reading the continuous discrete points of the printing path one by one, recording the included angle of every three continuous discrete points, comparing the recorded included angle with the critical angle for speed reduction judgment, and if it is less than the critical angle, it means that there is a corner or an arc in the printing path.

[0018] Further, the critical angle is 180°.

[0019] Further, the chord length ratio is the ratio of the distance between the starting point and the ending point and the distance from the highest point in the corner / arc to the chord length.

[0020] The beneficial effects of the present application are:

[0021] 1.The corner speed reduction method for continuous fiber 3D printing based on corner curvature characteristics provided by the application takes the curvature and chord length ratio as the theoretical calculation basis, intelligently reduces the speed when there is a circular arc or corner in the continuous fiber path, solves the problems of fiber twisting, fiber misplacement and fiber breakage that are usually caused by the existing 3D printing process, improves the bonding effect of the corner of the continuous fiber path, fully plays the effect of continuous fiber reinforced composite materials, improves the printing efficiency and quality of continuous fibers, and further improves the mechanical properties of the whole fiber reinforced composite material component.

[0022] 2.When it is judged that there is a corner, the method of the application reduces the printing speed by a certain distance in advance and delays the speed reduction printing, appropriately expands the speed change area, and can ensure the printing quality of the corner or circular arc of the continuous fiber path.

[0023] 3.The method of the application can accurately calculate the bending feature composed of fewer points through density refinement processing, avoid missing calculation of the corner, and improve the printing quality. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 The figure is a flowchart of the 3D printing method for reducing the printing speed of the corner of the continuous fiber path provided by the application.

[0025] Figure 2 The figure is a local schematic diagram of the target part.

[0026] Figure 3 The figure is a schematic diagram of the printing effect of the target part, and the printing speed F is 4mm / s.

[0027] Figure 4 The figure is a schematic diagram of the printing effect of the target part, and the printing speed F is 2mm / s.

[0028] Figure 5 The figure is a schematic diagram of the printing effect of the target part, and the printing speed F is 1mm / s.

[0029] BRIEF DESCRIPTION OF DRAWINGS

[0030] 1-continuous fiber path, 2-path corner. DETAILED DESCRIPTION

[0031] The technical solutions provided by the application will be described in detail below in combination with specific embodiments. It should be understood that the following specific embodiments are only used to illustrate the application and not to limit the scope of the application. It should be noted that the words "front", "back", "left", "right", "up" and "down" used in the following description refer to the directions in the drawings, and the words "in" and "out" refer to the directions towards or away from the geometric center of a particular component.

[0032] In this example, a thin-walled grid with 10x10, i.e. 100 squares (such as Figure 2 Fig. 1 shows a target part 1, wherein the square cell size is 10x10mm, the wall thickness is 2mm, and the printing material used is continuous carbon fiber reinforced polyamide (CCF / PA) composite wire.

[0033] Fig. 2 shows a 3D printing method for reducing the printing speed of a continuous fiber path corner according to the present application, which is applied to the target part shown in Fig. 1, and the flow thereof is as shown in Fig. 2. Figure 1 Fig. 2 shows a 3D printing method for reducing the printing speed of a continuous fiber path corner according to the present application, which is applied to the target part shown in Fig. 1, and the flow thereof is as shown in Fig. 2.

[0034] Step 1: Obtain the 3D printing model of the target part, and input the pre-deceleration distance n1 = 1mm and the post-deceleration distance n2 = 1mm. The pre-deceleration distance n1 and the post-deceleration distance n2 are setting parameters in the method, and are irrelevant to whether there is a corner or an arc in the path. The purpose of setting these two parameters is to appropriately expand the speed change area to ensure the printing quality of the continuous fiber path corner or arc.

[0035] Step 2: When the bending feature is composed of too few points, it will cause the bending feature (curvature / chord length ratio) to be unable to be accurately calculated. In order to more accurately find the curve path for speed reduction processing, the present application sets a critical density parameter (in this example, it is set that there is only 1 point under a path length of 1cm), analyzes the path of the 3D printing model, and judges that there are 2 points under a path of 10cm. Since the point density in the current printing path is less than the critical point density, the path points need to be refined in density, that is, the point insertion operation is performed in the printing path to improve the point density to reach the critical density.

[0036] Step 3: Perform critical condition judgment and segmentation (i.e., separate the printing paths that meet the critical condition and the printing paths that do not meet the critical condition) on the 3D printing model to obtain a plurality of sub-printing models. For the printing model that meets the critical condition, the corresponding optimal printing speed is calculated according to the curvature or chord length ratio. Specifically, the present step includes the following sub-steps:

[0037] (1) Critical condition judgment: First, perform path data acquisition, read each of the continuous discrete points of the printing path, record the included angle of every three continuous discrete points, compare the recorded included angle with the critical angle of speed reduction, if it is greater than the critical angle 180°, no speed reduction is needed, and the corner is ignored; if it is less than the critical angle, it means that the printing path has a corner or an arc, and speed reduction processing is needed. Whether the included angle of three continuous discrete points is less than the critical included angle 180° is the critical condition set in this example, which can be adjusted as needed (for example, multiple judgment verifications can be performed on the included angles of multiple groups of adjacent discrete points), and the critical included angle 180° can also be adjusted as needed.

[0038] (2) Use appropriate methods to calculate the optimal printing speed: In this example, we choose to calculate the curvature. The continuous fiber prints the non-corner area at a speed of 5mm / s. When the continuous fiber printing path 1 encounters the following Figure 2 After the path turns to corner 2, the curvature value k=0.2 at the path corner is calculated, and the optimal printing speed (2 mm / s) is calculated by f(k, v). Table 1 below is an example of a corresponding table of curvature and optimal printing speed.

[0039] Table 1

[0040]

[0041] f(k, v) is a pre-established relationship or equation between curvature k and optimal printing speed v. Initially, multiple printing experiments should be conducted on paths with corners at different printing speeds. The curvature at each point in the path and the optimal printing speed should be recorded. This will establish the corresponding equation f(k, v) between curvature k and optimal printing speed v. During the experiment, the print speed adjustment gradient should be minimized to achieve the best results. Experiments should be conducted for various corner configurations and various printing materials, and the corresponding equation f(k, v) should be established for each. When calculating the optimal printing speed, the corresponding equation f(k, v) for the same printing material and corner configuration can be used for more accurate results.

[0042] The chord length ratio can also be calculated to obtain the optimal printing speed: record the distance between the starting point and the end point of the arc in the continuous fiber printing path and the distance from the highest point in the arc to the chord length, and their ratio is recorded as the chord length ratio. In the early stage, multiple printing experiments should be carried out on the path with an arc using different printing speeds, and the chord length ratio of each point in the path, as well as the maximum printable speed and the minimum printable speed, should be recorded to establish the corresponding relationship f(m, v1, v2) between the chord length ratio m and the corresponding maximum printable speed v1 and minimum printable speed v2. According to f(m, v1, v2), v1 and v2 corresponding to the chord length ratio can be obtained. Calculate the printing speed v3 of any point in the arc = (the degree of the point / π) × the maximum speed v1. The degree of the point refers to the angle between the current point and the starting point and the end point of the arc in the printing path. If the calculated printing speed v3 is less than the minimum speed v2, the minimum speed v2 is taken as the printing speed v, expressed as follows:

[0043]

[0044] In this example, the continuous fiber prints the non-corner area at a speed of 5 mm / s. When the continuous fiber printing path 1 encounters Figure 1After the path corner 2, the chord ratio m = 2 at the path corner is calculated, at this time the corresponding maximum printable speed v1 = 4 mm / s, the minimum printable speed v2 = 1 mm / s. The printing speed v3 = (1 / 2) x 4 = 2 mm / s.

[0045] The optimal printing speed calculated by the chord ratio is complex, and the maximum printable speed v1 and the minimum printable speed v2 need to be obtained by experiments, but its accuracy and feasibility are higher.

[0046] Step four: trace back the distance n1 and the distance n2, and perform the operation of reducing the printing speed in advance, that is, the optimal printing speed is used at the distance corner n1, and the original printing speed is restored until the distance corner n2.

[0047] Figure 3 In order to print the above-mentioned thin-walled grid at F 4 mm / s, it can be clearly seen from the figure that the corner produces deflection, deviates from the printing path, and cannot form a right angle. Figure 4 As shown, after the 3D printing method provided by the application is used to reduce the printing speed of the continuous fiber path corner, the printing speed is reduced to F 2 mm / s, the grid can form a 90° right angle, and the right angle quality is excellent. It should be noted that the curvature and chord ratio calculation can obtain the result. As shown, Figure 5 As shown, after printing at a lower printing speed F1 mm / s, the continuous fiber again appears to be twisted, and the printing corner quality is reduced. Obviously, the printing effect is best by using the method of the application.

[0048] It should be noted that the above content only illustrates the technical idea of the application, and cannot limit the protection scope of the application. For ordinary skilled persons in the technical field, without departing from the principles of the application, a number of improvements and refinements can be made, which fall within the protection scope of the claims of the application.

Claims

1. A method for reducing the speed of continuous fiber 3D printing corners based on corner curvature characteristics, characterized in that: The steps include: Step 1: Obtain a 3D printed model and set the advance deceleration distance and the delayed deceleration distance; Step 2: Obtain the point density on the printing path in the 3D printing model, make a judgment based on the preset critical density parameter, and perform density refinement on the printing path with a point density less than the critical density parameter; Step 3: Collect the printing path data in the 3D printing model and perform critical condition judgment. The path that meets the critical condition is judged as a corner or an arc. The optimal printing speed corresponding to the corner path is calculated based on the structural parameters of the corner or arc, the structural parameters obtained in advance, and the optimal printing speed relationship. The process of calculating the optimal printing speed corresponding to the corner path based on the structural parameters of the corner or arc combined with the pre-obtained structural parameters and the optimal printing speed relationship includes: Calculate the curvature value at the path corner or arc, and calculate the optimal printing speed through f(k, v). f(k, v) is the corresponding relationship between the curvature value k and the optimal printing speed v established through multiple experiments; or Record the chord length ratio of the corner / arc in the printing path, and obtain the maximum printable speed v1 and minimum printable speed v2 based on the corresponding relationship between the chord length ratio and speed. Calculate the printing speed v3 of any point in the arc = (degrees of the point / π) × maximum speed v1. If the calculated printing speed v3 is less than the minimum speed v2, the minimum speed v2 is used as the printing speed v. The corresponding relationship between the chord length ratio and speed is the relationship f(m, v1, v2) between the maximum printable speed v1 and the minimum printable speed v2 corresponding to the chord length ratio m, established through multiple experiments. Step 4: Print at the optimal printing speed in advance at a distance from the corner n1, and maintain the optimal printing speed until the original printing speed is restored at a distance from the corner n2.

2. The method for reducing the speed at a corner of continuous fiber 3D printing based on corner curvature characteristics according to claim 1, characterized in that: The density refinement process in step 2 includes: performing a point insertion operation in the printing path.

3. The method for reducing the speed of continuous fiber 3D printing corners based on corner curvature characteristics according to claim 1, wherein the process of collecting printing path data in the 3D printing model and performing critical condition judgment in step 3 comprises: Read the continuous discrete points of the printing path one by one, record the angle between every three consecutive discrete points, and compare the recorded angle with the critical angle used for speed reduction judgment. If it is less than the critical angle, it means that there is a corner or arc in the printing path.

4. The method for reducing the speed of continuous fiber 3D printing corners based on corner curvature characteristics according to claim 1, wherein the critical angle is 180°.

5. The method for reducing the speed at a corner of continuous fiber 3D printing based on corner curvature characteristics according to claim 1, wherein the chord length ratio is the ratio of the distance between the starting point and the end point to the distance from the highest point in the corner / arc to the chord length.

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