A fast printing method based on adaptive honeycomb partitioning

Abstract

The present invention relates to the field of metal laser 3D printing manufacturing technology, and in particular to a rapid printing method based on adaptive honeycomb partitioning, comprising: analyzing a finished printed part through stress simulation software to obtain a stress distribution map of the area to be printed; constructing honeycomb partitions with the same honeycomb unit size in the same printing coordinate system to cover the area to be printed; adaptively adjusting the honeycomb unit size of honeycomb partitions with the same honeycomb unit size in the printing area based on the stress distribution map of the area to be printed; and obtaining a printed part based on the adaptive honeycomb partitioning as a printing trajectory. The present invention achieves stress reduction in high-stress areas by adaptively adjusting the honeycomb unit size of the honeycomb partitions, thereby making the stress in each area of ​​the part more evenly distributed; at the same time, it reduces the number of honeycomb partitions in low-stress areas, thereby overcoming the slow printing speed disadvantage of traditional chessboard scanning or honeycomb scanning.

Description

Technical Field

[0001] The present invention relates to the technical field of metal laser 3D printing manufacturing, and in particular to a rapid printing method based on adaptive honeycomb partitioning. Background Art

[0002] Metal laser 3D printing uses a layer-by-layer method of adding metal powder. For each layer to be printed, the metal powder is evenly spread on the printing platform. The laser melts the powder point by point along a preset path, causing the powder in adjacent paths to melt and sinter into shape. After completing a single layer, the next layer is printed until the entire metal part is printed.

[0003] In one aspect of the prior art, the laser scanning path uses a strip scanning method, printing in parallel strips on each layer line by line. The continuous scanning partition is large, which affects the distribution of stress and the accumulated residual stress after cooling is large, such as Figure 1a-Figure 1b Another aspect of the prior art is that the laser scanning path can use a chessboard scanning or honeycomb partition scanning method to divide the printing area into several small blocks similar to a chessboard or honeycomb layout, and alternately print adjacent small blocks. The chessboard scanning method is as follows: Figure 2a-2b As shown; However, chessboard scanning or honeycomb layout scanning slows down the laser scanning speed and increases the printing time due to the increase of jump paths; In addition, the prior art uses chessboard scanning or honeycomb partition scanning, and its scanning basic unit / partition unit is often fixed. The prior art honeycomb partition scanning method prints parts such as Figure 3 As shown, there are large differences in stress between different regions. Summary of the Invention

[0004] In view of the above analysis, the present invention aims to provide a fast printing method based on adaptive honeycomb partitioning to solve at least one of the problems in the prior art, such as large residual stress, slow printing speed, and uneven stress in the printing area.

[0005] The purpose of the present invention is mainly achieved through the following technical solutions:

[0006] The present invention provides a fast printing method based on adaptive honeycomb partitioning, comprising:

[0007] Analyze the printed parts through stress simulation software to obtain the stress distribution map of the area to be printed;

[0008] Construct honeycomb partitions with the same honeycomb unit size in the same printing coordinate system to cover the area to be printed;

[0009] Based on the stress distribution map of the area to be printed, the honeycomb cell sizes of the honeycomb partitions with the same honeycomb cell size in the printing area are adaptively adjusted to obtain adaptive honeycomb partitions with more balanced stress distribution;

[0010] A printed product is obtained based on the adaptive honeycomb partitions as a printing trajectory.

[0011] Preferably, obtaining an adaptive honeycomb partition with a more balanced stress distribution includes: adjusting the vertex positions of the honeycomb partition according to the stress distribution diagram of the area to be printed, so that the elastic potential energy of the spring system composed of the vertices in any two honeycomb partitions is substantially the same.

[0012] Preferably, obtaining an adaptive honeycomb partition with a more balanced stress distribution includes:

[0013] S301: constructing a double-mass spring system by grouping adjacent vertices in the honeycomb partition into pairs, and calculating the elastic potential energy of the spring system;

[0014] S302: Calculate the resultant force of the three adjacent vertices on the vertex of the honeycomb partition, and obtain the resultant force on the vertices of all honeycomb partitions

[0015] S303: Displace the vertices of all honeycomb partitions in the direction of the resultant force on them

[0016]

[0017] S304: Yes Numerical judgment of:

[0018] When the displacement of all vertices of the cell partition If the value of <e, the honeycomb partition completes the adaptive change, and the connection line of the honeycomb partition vertices can be used as a printing track;

[0019] When the displacement of the vertices of all honeycomb partitions If the value of ≥e, the cell partition has not completed the adaptive change, and S301-S303 are repeated until The value of is less than e.

[0020] Preferably, calculating the elastic potential energy of the spring system in S301 includes:

[0021] The energy density U of all spring systems is obtained from the stress distribution diagram at each position of the honeycomb partition side length;

[0022] The energy density U of all spring systems is integrated at each position along the side of the honeycomb partition to obtain the elastic potential energy of each spring system.

[0023] Preferably, calculating the elastic potential energy of the spring system in S301 includes:

[0024] S3011: Convert the stress distribution diagram into a two-dimensional plane coordinate system with the distance between the two end points of the spring system as a variable and the stress as the dependent variable;

[0025] S3012: Subdivide the line segment between the two end points of the spring system into multiple small segments, with the distance between each small segment being δ;

[0026] S3013: Based on the center point of each small segment, find the stress at that point on the stress distribution diagram and use it as the average stress σ of the small segment;

[0027] S3014: Calculate the average value of the energy density U of the segment based on the average stress σ according to the energy density calculation formula;

[0028] S3015: multiplying the average value of the energy density U of the small segment by the length δ of the small segment to obtain the strain energy E1 of the small segment;

[0029] S3016: Based on the above steps, the strain energies of all small segments are obtained, and the elastic potential energy of the spring system is obtained by summing the strain energies of all small segments.

[0030] Preferably, the calculation formula for energy density in S3014 satisfies:

[0031] Where E is the Young's modulus of the material.

[0032] Preferably, S3012 may be 0.0005 to 0.002 of the distance between the two end points of the spring system.

[0033] Preferably, S303 includes: processing the vertices of all honeycomb partitions in sequence from one side to the other side of the area to be printed based on the vertex coordinates of the honeycomb partitions.

[0034] Preferably, the vertex coordinates based on the honeycomb partitions include: comparing and screening the vertex coordinates, horizontal coordinates and vertical coordinates of all honeycomb partitions, and further determining the processing order of the vertex coordinates of all honeycomb partitions according to the sorting result.

[0035] Preferably, the printed product is prepared by printing using the following method, including: scanning the track using honeycomb partitions with fixed honeycomb unit sizes.

[0036] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects:

[0037] (1) The present invention adaptively adjusts the size of honeycomb units in honeycomb partitions. On the one hand, for the areas with relatively large stress in the stress distribution diagram, stress reduction in the large stress areas is achieved, thereby avoiding the problem of large cold-accumulated residual stress in the prior art, which is prone to cause local cracking. On the other hand, in addition to reducing the stress in the large stress areas, the original honeycomb partition size is appropriately increased and the number of honeycomb partitions is reduced for the areas with relatively small stress, so that the stress in each area of ​​the workpiece is relatively uniform. In addition, for the areas with relatively small stress, the number of honeycomb partitions is not increased, and thus the jump path is not increased, thereby ensuring a faster laser scanning speed and printing speed, and overcoming the defect of slow printing speed in traditional chessboard scanning or honeycomb scanning. Compared with traditional chessboard scanning or honeycomb partition scanning with fixed honeycomb unit size, the present invention improves printing efficiency while reducing the difference in residual stress.

[0038] (2) The present invention constructs a double-mass spring system by grouping adjacent vertices in the vertices of the honeycomb partitions in pairs, calculates the elastic potential energy of all spring systems and the resultant force on the vertices of all honeycomb partitions, displaces the vertices of the core honeycomb partition in the direction of the resultant force, and calculates the elastic potential energy of all spring systems after each displacement. This realizes the adaptive adjustment of the vertices of the honeycomb partitions and obtains the honeycomb partitioning scheme with the lowest stress and stress energy (elastic potential energy). Compared with the partitioning scheme of the prior art in which the honeycomb unit size remains unchanged, this method overcomes the defect that the residual stress in some areas is large and easily causes local cracks, and also makes the stress in each area of ​​the workpiece more uniform.

[0039] (3) The present invention constructs an elastic potential energy model with the vertices of the honeycomb partition as the center of mass, converts the stress energy of the honeycomb partition in the printing area into the elastic potential energy of the spring system where the vertices of the honeycomb partition are located for analysis and dimensionality reduction, which greatly simplifies the calculation process and improves the calculation speed.

[0040] In the present invention, the above-mentioned technical solutions can be combined with each other to achieve more preferred combination solutions. Other features and advantages of the present invention will be described in the subsequent description, and some advantages will become apparent from the description or be understood through practice of the present invention. The objectives and other advantages of the present invention can be achieved and obtained through the embodiments of the description and the contents particularly pointed out in the drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] The accompanying drawings are only for the purpose of illustrating particular embodiments and are not to be considered limiting of the present invention. Like reference symbols denote like parts throughout the drawings.

[0042] Figure 1a A schematic diagram of a scanning trajectory of a strip scan in the prior art;

[0043] Figure 1bIt is a simulation analysis of strip scanning parts in the existing technology;

[0044] Figure 2a A schematic diagram of a scanning trajectory of a chessboard scan in the prior art;

[0045] Figure 2b Simulation analysis of chessboard scanning parts in the prior art;

[0046] Figure 3 Simulation analysis of honeycomb partition printing parts with fixed honeycomb unit size in the prior art;

[0047] Figure 4 This is the elastic vibration model of the honeycomb partition endpoint in the embodiment of the present invention;

[0048] Figure 5 Schematic diagram of calculating the stress energy or elastic potential energy of a spring system according to the present invention;

[0049] Figure 6 Printed parts prepared for embodiments of the present invention or subjected to stress analysis;

[0050] Figure 7 This is a schematic diagram of the combined force of the endpoints of the cellular partitions according to embodiment 1 of the present invention;

[0051] Figure 8 Schematic diagram of the displacement of the endpoints of the honeycomb partitions in the direction of the resultant force according to Example 1 of the present invention;

[0052] Figure 9 This is a simulation analysis of the printed part prepared after adaptive honeycomb partitioning in Example 1 of the present invention.

[0053] Reference numerals:

[0054] Two-mass-spring system 01; vertex 011 of honeycomb partition; honeycomb partition 02. DETAILED DESCRIPTION

[0055] The preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings, wherein the accompanying drawings constitute a part of the present invention and are used together with the embodiments of the present invention to illustrate the principles of the present invention, but are not used to limit the scope of the present invention.

[0056] The applicant's research has found that residual stress varies across different locations in metal laser 3D printing. Depending on the shape of the printed part, stress can vary significantly between different regions, with stress generally being greater at the edges than in the center. Fixed-size partitions can lead to significant variations in the distribution of residual stress across the printed part, making it difficult to eliminate the residual stress during subsequent stress-relieving annealing. When the stress distribution is severely uneven, areas with particularly high local stress can even warp and crack.

[0057] By uniformly shrinking the partitions, stress can be reduced, thereby reducing the difference in stress distribution. However, the printing efficiency will be significantly reduced: because the laser needs to jump between different partitions, the more partitions there are, the lower the printing efficiency will be due to frequent laser jumps.

[0058] Therefore, in the existing technology, metal laser 3D printing, whether it is chessboard scanning or strip scanning, uses a partitioning method with a fixed scanning unit size. Under this partitioning method, the contradiction between "reducing residual stress differences" and "improving printing efficiency" is difficult to reconcile.

[0059] In one aspect, the present invention discloses a fast printing method based on adaptive cellular partitioning, comprising:

[0060] S1: Analyze the printed product through stress simulation software to obtain the stress distribution map of the area to be printed;

[0061] S2: Construct honeycomb partitions with the same honeycomb unit size in the same printing coordinate system to cover the area to be printed;

[0062] S3: Adaptively adjusting the honeycomb cell sizes of honeycomb partitions with the same honeycomb cell size in the printing area based on the stress distribution map of the area to be printed, to obtain adaptive honeycomb partitions with more balanced stress distribution;

[0063] S4: Obtain a printed part based on the adaptive honeycomb partition obtained in S3 as a printing trajectory.

[0064] During implementation, on the one hand, for areas with higher stress in the stress distribution diagram, the original honeycomb partition size is reduced and the number of honeycomb partitions is increased to reduce the stress in the corresponding area; on the other hand, for areas with lower stress, the original honeycomb partition size is appropriately increased and the number of honeycomb partitions is reduced to make the stress in each area of ​​the workpiece more uniform; in addition, an adaptive adjustment method based on the stress distribution diagram of the printing area is adopted to realize feedback regulation from output to input, which helps to obtain the optimal stress output result.

[0065] Compared with the prior art, the present invention adaptively adjusts the size of honeycomb units in honeycomb partitions. On the one hand, for areas with relatively high stress in the stress distribution diagram, stress reduction in large stress areas is achieved, thereby avoiding the problem of large cold-accumulated residual stress in the prior art, which easily causes local cracking. On the other hand, in addition to reducing stress in large stress areas, the present invention appropriately increases the size of the original honeycomb partitions in areas with relatively low stress, and reduces the number of honeycomb partitions, so that the stress in each area of ​​the workpiece is relatively uniform. In addition, for areas with relatively low stress, the number of honeycomb partitions is not increased, and thus the jump path is not increased, thereby ensuring a faster laser scanning speed and printing speed, and overcoming the slow printing speed defect of traditional chessboard scanning or honeycomb scanning. Compared with traditional chessboard scanning or honeycomb partition scanning with fixed honeycomb unit size, the present invention improves printing efficiency while reducing residual stress differences.

[0066] Specifically, the stress simulation software in S1 can be any one of ANSYS, Amphyon, and Netfabb.

[0067] During implementation, the shape and material of the area to be printed are input to output the stress distribution map of the area to be printed. Since 3D printing is performed by printing and stacking layers with surfaces as printing units, it is only necessary to determine the printing trajectory of one surface (printing area).

[0068] As an example, Figure 6 For the part to be printed shown, it is only necessary to determine the printing trajectory of the AA section.

[0069] It should be noted that the present invention addresses the problems of large local stress and uneven stress in different regions in printing in the prior art. Therefore, the printed parts prepared by the prior art can be used as input to the stress simulation software in S1 to obtain the stress distribution map of the area to be printed, and use it as the basis for adaptive adjustment of honeycomb partitions.

[0070] Specifically, the method for obtaining the printed product may be honeycomb partitioning with a fixed honeycomb unit size, strip scanning partitioning, or chessboard scanning partitioning.

[0071] Specifically, the raw material of the printed part can be titanium alloy, aluminum alloy, high-temperature alloy or stainless steel.

[0072] Specifically, the side length of the initial honeycomb partition constructed by S2 is 10 mm to 20 mm.

[0073] It should be noted that sharing a coordinate system between the honeycomb partition and the stress distribution diagram facilitates subsequent honeycomb adaptive adjustment and calculation. The honeycomb sizes matched with different source materials are different, and changes in scanning power will also affect the honeycomb size. The present invention sets the initial honeycomb partition side length to 10 mm to 20 mm, which has good applicability for different types of alloys.

[0074] Specifically, in S3, the honeycomb cell sizes of the honeycomb partitions with the same honeycomb cell size in the printing area are adaptively adjusted, including: adjusting the vertex positions of the honeycomb partitions according to the stress distribution diagram of the area to be printed, so that the elastic potential energy of the spring system composed of the vertices in any two honeycomb partitions is basically the same.

[0075] It should be noted that if Figure 3 As shown in FIG, the stress distribution diagram of the area to be printed is the stress distribution diagram at different positions. When the stress is not 0, it is considered that stress energy exists.

[0076] During implementation, the present invention constructs an elastic potential energy model with the vertices of the honeycomb partitions as the center of mass, converts the stress energy of the honeycomb partitions in the printing area into the elastic potential energy of the spring system where the vertices of the honeycomb partitions are located for analysis and dimensionality reduction, thereby greatly simplifying the calculation process and improving the calculation speed.

[0077] Specifically, S3 includes:

[0078] S301: constructing a double-mass spring system by grouping adjacent vertices in the honeycomb partition into pairs, and calculating the elastic potential energy of the spring system;

[0079] S302: Calculate the resultant force of the three adjacent vertices on the vertex of the honeycomb partition, and obtain the resultant force on the vertices of all honeycomb partitions

[0080] S303: Displace the vertices of all honeycomb partitions in the direction of the resultant force on them

[0081] S304: Yes Numerical judgment of:

[0082] When the displacement of the vertices of all honeycomb partitions If the value of <e, the honeycomb partition completes the adaptive change, and the connection line of the honeycomb partition vertices can be used as a printing track;

[0083] When the displacement of the vertices of all honeycomb partitions If the value of ≥e, the cell partition has not completed the adaptive change, and S301-S303 are repeated until The value of is less than e or the number of iterations reaches the upper limit.

[0084] It should be noted that the upper limit of the number of iterations is set to avoid The value of is to satisfy <e infinite iterations that waste time and material costs; when the upper limit of the number of iterations is reached, If the value ≥ e, it means that the e value is set improperly and exceeds the system capability.

[0085] Specifically, k satisfies: k and the resultant force of each stress The product of the maximum values ​​of takes 0.2‰~0.5‰ of the side length of the honeycomb partition. e takes 0.05‰~0.2‰ of the side length of the honeycomb partition.

[0086] Specifically, if Figure 4 As shown, S301 constructs a dual-mass spring system including: two elastically connected vertices of honeycomb partitions; the vertex of each honeycomb partition and the vertices of the three adjacent honeycomb partitions form a spring oscillator model, and the vertex of each honeycomb partition is simultaneously subjected to the tension / pressure of the vertices of the three adjacent honeycomb partitions. The vertex of the honeycomb partition and the three adjacent honeycomb partitions form three spring systems, and the tension / pressure in the spring system is stored in the form of elastic potential energy.

[0087] It should be noted that the vertex of the honeycomb partition calculated in S302-S303 is subject to the combined force of its three adjacent vertices. Displace the vertices of all honeycomb partitions in the direction of the resultant force on them Because of the combined force displacement in the direction, so that the net force Work is done, thereby reducing the total stress and total elastic potential energy of the three spring systems with the vertex of a certain honeycomb partition as the core; thus, after each iteration and the adjustment of the vertex position of the honeycomb partition, the total stress and total elastic potential energy of the honeycomb partition are reduced; at the same time, due to the displacement of the area with large stress A larger value will make the adjustment of the vertex position of the honeycomb partition in the area with large stress greater, which will help to increase the iteration speed, make the stress difference in each area disappear quickly, and achieve stress balance in each area; at the same time, due to the resultant force on the vertex of the honeycomb partition of the vector parameter With the introduction of , the above method can simultaneously handle stresses in various directions, including tension, pressure, outward tension, etc.

[0088] Compared with the prior art, the present invention constructs a double-mass spring system by grouping adjacent vertices in the vertices of the honeycomb partitions in pairs, calculates the elastic potential energy of all spring systems and the resultant force acting on the vertices of all honeycomb partitions, displaces the vertices of the core honeycomb partition in the direction of the resultant force, and calculates the elastic potential energy of all spring systems after each displacement. This achieves adaptive adjustment of the vertices of the honeycomb partitions and obtains a honeycomb partitioning scheme with the lowest stress and stress energy (elastic potential energy). Compared with the prior art partitioning scheme with unchanged honeycomb unit size, this overcomes the defect of large residual stress in some areas, which is prone to local cracking, and also makes the stress in each area of ​​the workpiece more uniform.

[0089] Specifically, calculating the elastic potential energy of the spring system in S301 includes:

[0090] The energy density U of all spring systems is obtained from the stress distribution diagram at each position of the honeycomb partition side length;

[0091] The energy density U of all spring systems is integrated at each position along the side of the honeycomb partition to obtain the elastic potential energy of each spring system.

[0092] Specifically, calculating the elastic potential energy of the spring system in S301 includes:

[0093] S3011: Convert the stress distribution diagram into a two-dimensional plane coordinate system with the honeycomb partition side length (the distance between the two end points of the spring system) as a variable and stress as the dependent variable;

[0094] S3012: Subdivide the line segment between the two end points of the spring system into multiple small segments, with the distance between each small segment being δ;

[0095] S3013: Based on the center point of each small segment, find the stress at that point on the stress distribution diagram and use it as the average stress σ of the small segment;

[0096] S3014: Calculate the average value of the energy density U of the segment based on the average stress σ according to the energy density calculation formula;

[0097] S3015: multiplying the average value of the energy density U of the small segment by the length δ of the small segment to obtain the strain energy E1 of the small segment;

[0098] S3016: Based on the above steps, the strain energies of all small segments are obtained, and the elastic potential energy of the spring system is obtained by summing the strain energies of all small segments.

[0099] Specifically, regarding the coordinate system transformation in S3011, Figure 5 For example: Figure 5 The left side provides a stress distribution diagram of stress in the plane coordinate system, and the color depth indicates the stress magnitude; Figure 5 The right side provides a stress distribution diagram of the two-dimensional plane coordinate system in the enlarged area on the left, with the side length of the honeycomb partition (the distance between the two end points of the spring system) as the variable and stress as the dependent variable; Figure 5 The right side can be Figure 5 The stress distribution diagram on the left is obtained from the source data.

[0100] Specifically, to facilitate calculation and ensure accuracy, δ in S3012 may be 0.0005 to 0.002 of the distance between the two end points of the spring system.

[0101] Specifically, the calculation formula for energy density in S3014 satisfies:

[0102] Where E is the Young's modulus of the material.

[0103] Preferably, in S303, the vertices of all honeycomb partitions are displaced in the direction of the resultant force on them. The method comprises: based on the vertex coordinates of the honeycomb partitions, processing the vertices of all honeycomb partitions in sequence from one side to the other side of the area to be printed.

[0104] Specifically, the vertex coordinates, horizontal coordinates and vertical coordinates of all honeycomb partitions are compared and screened, and the processing order of the vertex coordinates of all honeycomb partitions is further determined based on the sorting results.

[0105] As an example, set the rules to process from the left to the right of the area to be printed:

[0106] S3031: Compare the horizontal coordinates of the vertices of all honeycomb partitions and sort them from small to large;

[0107] S3032: Sort the horizontal coordinates of the vertices of all honeycomb partitions as the processing order of the vertices of all honeycomb partitions.

[0108] It should be noted that the first iterative adjustment of the vertex position of the honeycomb partition in S3 causes a large change, and the change will inevitably affect the vertices of the adjacent honeycomb partitions. Therefore, it is particularly important to determine the processing order of the honeycomb partition vertices; according to the above S3031~S3032, the processing order of the vertices of the honeycomb partition is determined, which can reduce the impact of the vertex position change of the honeycomb partition on the vertices of the adjacent honeycomb partitions to a certain extent.

[0109] In order to better illustrate the present invention, the following examples are provided:

[0110] Example 1

[0111] This embodiment discloses a fast printing method based on adaptive cellular partitioning, including:

[0112] S1: Through ANSYS stress simulation software, Figure 6 The AA section stress analysis of the printed part is obtained Figure 3 Stress distribution diagram of the area to be printed; the part to be printed is a rectangular base with a rectangular boss structure fixedly connected to the center, with a boss width a1 = 82mm and a boss height h1 = 86mm; the distance between the boss and the two sides of the base is a2 = 36mm; the base height h2 = 26mm; the printing material is TA15 titanium alloy.

[0113] Figure 6 The middle product is a honeycomb partition printed product with the same honeycomb unit size in the prior art, with a honeycomb partition side length of 10 mm, a laser scanning rate of 1000 mm / s, and a laser power of 300 W, which are the same as those in S4 of this embodiment;

[0114] S2: Construct honeycomb partitions with the same honeycomb unit size in the same printing coordinate system to cover the area to be printed; the side length of the initial honeycomb partition constructed by S2 is 10 mm.

[0115] S3: Adaptively adjusting the honeycomb cell sizes of honeycomb partitions with the same honeycomb cell size in the printing area based on the stress distribution map of the area to be printed, to obtain adaptive honeycomb partitions with more balanced stress distribution;

[0116] S301: constructing a double-mass spring system by grouping adjacent vertices in the honeycomb partition into pairs, and calculating the elastic potential energy of the spring system;

[0117] like Figure 4 As shown, S301 constructs a double-mass spring system 01 including: two elastically connected vertices 011 of honeycomb partitions, and at the same time, the vertex 011 of each honeycomb partition and the vertices 011 of the three adjacent honeycomb partitions form a more complex spring system. The vertex of each honeycomb partition is simultaneously subjected to the tension / pressure of the vertices of the three adjacent honeycomb partitions. The vertex of the honeycomb partition and the three adjacent honeycomb partitions form three spring systems, and the tension / pressure in the spring system is stored in the form of elastic potential energy.

[0118] S3011: Convert the stress distribution diagram into a two-dimensional plane coordinate system with the honeycomb partition side length (the distance between the two end points of the spring system) as a variable and stress as the dependent variable;

[0119] S3012: Subdivide the line segment between the two end points of the spring system into multiple small segments, with the distance of each small segment being δ; δ is 0.001 of the distance between the two end points of the spring system.

[0120] S3013: Based on the center point of each small segment, find the stress at that point on the stress distribution diagram and use it as the average stress σ of the small segment;

[0121] S3014: According to the calculation formula of energy density, the average value of the energy density U of the small segment is calculated based on the average stress σ; the calculation formula of energy density satisfies:

[0122] Wherein, E is the Young's modulus of the material, which is 110 GPa.

[0123] S3015: multiplying the average value of the energy density U of the small segment by the length δ of the small segment to obtain the strain energy E1 of the small segment;

[0124] S3016: Based on the above steps, the strain energies of all small segments are obtained, and the elastic potential energy of the spring system is obtained by summing the strain energies of all small segments.

[0125] S302: Calculate the resultant force of the three adjacent vertices on the vertex of the honeycomb partition, and obtain the resultant force on the vertices of all honeycomb partitions

[0126] like Figure 7 As shown, in Figure 7 The resultant force on the vertices of the honeycomb partition is given in the calculation of the honeycomb partition Three examples: In example A, the resultant force on the vertices of the honeycomb partition is As shown by the red arrow, the vertex of the honeycomb partition and the vertex of the adjacent honeycomb partition are connected in the direction of the side length of the honeycomb partition; the resultant force on the vertex of the honeycomb partition in area B of the example is As shown by the red arrows, the resultant force on the two vertices of the honeycomb partition in area C of the example As indicated by the red arrow.

[0127] S303: Displace the vertices of all honeycomb partitions in the direction of the resultant force on them

[0128]

[0129] S304: Yes Numerical judgment of:

[0130] When the displacement of the vertices of all honeycomb partitions If the value of <e, the honeycomb partition completes the adaptive change, and the connection line of the honeycomb partition vertices can be used as a printing track;

[0131] When the displacement of the vertices of all honeycomb partitions If the value of ≥e, the cell partition has not completed the adaptive change, and S301-S303 are repeated until The value is less than e or the number of iterations reaches the upper limit of 1000 times. e is 0.1‰ of the side length of the honeycomb partition; k satisfies: k and the resultant force of each stress The product of the maximum values ​​is taken as 0.5‰ of the side length of the honeycomb partition.

[0132] The setting rules are processed sequentially from the left to the right of the area to be printed:

[0133] S3031: Compare the horizontal coordinates of the vertices of all honeycomb partitions and sort them from small to large;

[0134] S3032: Sort the horizontal coordinates of the vertices of all honeycomb partitions as the processing order of the vertices of all honeycomb partitions.

[0135] like Figure 8 As shown, in Figure 8 The calculation of the resultant force on the vertex of the honeycomb partition is given in Three examples of directional displacement: In example A, the resultant force on the vertices of the honeycomb partition is As shown by the red arrow, the green position is the position of the honeycomb partition vertex after the first iterative displacement; the resultant force on the vertex of the honeycomb partition in area B of the example As shown by the red arrow, the green position is the position of the honeycomb partition vertex after the first iterative displacement; the resultant force on the two vertices of the honeycomb partition in area C of the example As shown by the red arrows, the green position is the position of the honeycomb partition vertex after the first iterative displacement.

[0136] S4: Based on the adaptive honeycomb partition obtained in S3 as the printing trajectory, the printed part is obtained. Figure 9 As shown, the adaptive cell partition 02 is irregularly distributed and is completely different from the initial state of the cell partition S2; and Figure 3 Compared with the parts prepared by honeycomb partitions with the same size of traditional honeycomb units, the stress in the large stress area is reduced, and the stress in each area is less than 20ksi, avoiding the problem of large cold-accumulated residual stress in the existing technology, which is easy to cause local cracking; in addition to reducing the stress in the large stress area, for the areas with smaller stress, the original honeycomb partition size is appropriately increased and the number of honeycomb partitions is reduced, so that the stress in each area of ​​the part is more even, and the stress unevenness between the areas is reduced; in addition, since the number of honeycomb partitions is not increased, the jump path is not increased, which ensures a faster laser scanning speed and printing speed, overcoming the slow printing speed defect of traditional chessboard scanning or honeycomb scanning; compared with traditional chessboard scanning or honeycomb partition scanning with fixed honeycomb unit size, the present invention improves printing efficiency while reducing the difference in residual stress.

[0137] Example 2

[0138] This embodiment discloses a fast printing method based on adaptive cellular partitioning, including:

[0139] S1: Through Netfabb stress simulation software, Figure 6 The stress distribution diagram of the to-be-printed area is obtained by stress analysis of the AA section of the to-be-printed part. The to-be-printed part is a rectangular base with a rectangular boss structure fixedly connected to the center. The boss width a1 = 82 mm, the boss height h1 = 86 mm; the distance between the boss and the two sides of the base a2 = 36 mm; the base height h2 = 26 mm; the printing material is AlSi10Mg aluminum alloy.

[0140] Figure 6 The middle part is a honeycomb partition printed part with the same honeycomb unit size as the prior art. The honeycomb partition side length is 10 mm. The laser scanning rate is 800 mm / s and the laser power is 400 W, which are the same as S4 in this embodiment.

[0141] S2: Construct honeycomb partitions with the same honeycomb unit size in the same printing coordinate system to cover the area to be printed; the side length of the initial honeycomb partition constructed by S2 is 10 mm.

[0142] S3: Adaptively adjusting the honeycomb cell sizes of honeycomb partitions with the same honeycomb cell size in the printing area based on the stress distribution map of the area to be printed, to obtain adaptive honeycomb partitions with more balanced stress distribution;

[0143] S301: constructing a double-mass spring system by grouping adjacent vertices in the honeycomb partition into pairs, and calculating the elastic potential energy of the spring system;

[0144] like Figure 4 As shown, S301 constructs a double-mass spring system 01 including: two elastically connected vertices 011 of honeycomb partitions, and at the same time, the vertex 011 of each honeycomb partition and the vertices 011 of the three adjacent honeycomb partitions form a more complex spring system. The vertex of each honeycomb partition is simultaneously subjected to the tension / pressure of the vertices of the three adjacent honeycomb partitions. The vertex of the honeycomb partition and the three adjacent honeycomb partitions form three spring systems, and the tension / pressure in the spring system is stored in the form of elastic potential energy.

[0145] S3011: Convert the stress distribution diagram into a two-dimensional plane coordinate system with the honeycomb partition side length (the distance between the two end points of the spring system) as a variable and stress as the dependent variable;

[0146] S3012: Subdivide the line segment between the two end points of the spring system into multiple small segments, with the distance of each small segment being δ; δ is 0.001 of the distance between the two end points of the spring system.

[0147] S3013: Based on the center point of each small segment, find the stress at that point on the stress distribution diagram and use it as the average stress σ of the small segment;

[0148] S3014: According to the calculation formula of energy density, the average value of the energy density U of the small segment is calculated based on the average stress σ; the calculation formula of energy density satisfies:

[0149] Wherein, E is the Young's modulus of the material, which is 75 GPa.

[0150] S3015: multiplying the average value of the energy density U of the small segment by the length δ of the small segment to obtain the strain energy E1 of the small segment;

[0151] S3016: Based on the above steps, the strain energies of all small segments are obtained, and the elastic potential energy of the spring system is obtained by summing the strain energies of all small segments.

[0152] S302: Calculate the resultant force of the three adjacent vertices on the vertex of the honeycomb partition, and obtain the resultant force on the vertices of all honeycomb partitions

[0153] S303: Displace the vertices of all honeycomb partitions in the direction of the resultant force on them

[0154]

[0155] S304: Yes Numerical judgment of:

[0156] When the displacement of the vertices of all honeycomb partitions If the value of <e, the honeycomb partition completes the adaptive change, and the connection line of the honeycomb partition vertices can be used as a printing track;

[0157] When the displacement of the vertices of all honeycomb partitions If the value of ≥e, the cell partition has not completed the adaptive change, and S301-S303 are repeated until The value of is less than e or the number of iterations reaches the upper limit of 1000. e is 0.1‰ of the side length of the honeycomb partition.

[0158] The setting rules are processed sequentially from the left to the right of the area to be printed:

[0159] S3031: Compare the horizontal coordinates of the vertices of all honeycomb partitions and sort them from small to large;

[0160] S3032: Sort the horizontal coordinates of the vertices of all honeycomb partitions as the processing order of the vertices of all honeycomb partitions.

[0161] S4: The printed part is obtained based on the adaptive honeycomb partition obtained in S3 as the printing trajectory. The adaptive honeycomb partition 02 is irregularly distributed and is completely different from the initial state of the S2 honeycomb partition. Compared with the parts prepared by traditional honeycomb partitions of the same area, the stress in the large stress area is reduced, and the stress in each area is less than 20ksi, avoiding the problem of large cold accumulated residual stress in the prior art, which is easy to cause local cracking. In addition to reducing the stress in the large stress area, for the area with smaller stress, the original honeycomb partition size is appropriately increased and the number of honeycomb partitions is reduced, so that the stress in each area of ​​the part is more average, and the stress unevenness between the areas is reduced. In addition, since the number of honeycomb partitions is not increased, the jump path is not increased, which ensures a faster laser scanning speed and printing speed, overcoming the defect of slow printing speed in traditional chessboard scanning or honeycomb scanning. Compared with traditional chessboard scanning or honeycomb partition scanning with fixed honeycomb unit size, the present invention improves printing efficiency while reducing the residual stress difference.

[0162] The above description is only a preferred specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by any technician familiar with this technical field within the technical scope disclosed by the present invention should be covered by the scope of protection of the present invention.

Claims

1. A fast printing method based on adaptive cellular partitioning, characterized in that: include: Analyze the printed parts through stress simulation software to obtain the stress distribution map of the area to be printed; Construct honeycomb partitions with the same honeycomb unit size in the same printing coordinate system to cover the area to be printed; Adaptively adjusting the honeycomb cell sizes of honeycomb partitions with the same honeycomb cell size in the printing area based on the stress distribution map of the printing area to obtain adaptive honeycomb partitions with more balanced stress distribution, including: adjusting the vertex positions of the honeycomb partitions based on the stress distribution map of the printing area so that the elastic potential energy of the spring system formed by the vertices in any two honeycomb partitions is the same; Adaptive honeycomb partitioning to achieve more balanced stress distribution includes: S301: constructing a double-mass spring system by grouping adjacent vertices in the honeycomb partition into pairs, and calculating the elastic potential energy of the spring system; S302: Calculate the resultant force of the three adjacent vertices on the vertex of the honeycomb partition, and obtain the resultant force on the vertices of all honeycomb partitions ; S303: Displace the vertices of all honeycomb partitions in the direction of the resultant force on them ; satisfy: and the resultant of each stress The product of the maximum value is 0.2‰ ~0.5‰ of the side length of the honeycomb partition; S304: Yes Numerical judgment of: When the displacement of the vertices of all honeycomb partitions The value of , then the honeycomb partition completes the adaptive change, and the connection line of the honeycomb partition vertices can be used as the printing trajectory; When the displacement of the vertices of all honeycomb partitions The value of ≥ , then the cellular partition has not completed the adaptive change, repeat S301-S303 until The value of ; Take 0.05‰ ~0.2‰ of the honeycomb partition side length; The calculation of the elastic potential energy of the spring system in S301 includes: The energy density U of all spring systems is obtained from the stress distribution diagram at each position of the honeycomb partition side length; The energy density U of all spring systems is integrated at each position along the side of the honeycomb partition to obtain the elastic potential energy of each spring system; S3011: Convert the stress distribution diagram into a two-dimensional plane coordinate system with the distance between the two end points of the spring system as a variable and the stress as the dependent variable; S3012: Divide the line segment between the two end points of the spring system into multiple small segments, and the distance of each small segment is ; 0.0005~0.002 of the distance between the two end points of the spring system; S3013: Based on the center point of each small segment, find the stress at that point on the stress distribution diagram as the average stress of the small segment ; S3014: According to the calculation formula of energy density, based on the average stress Calculate the energy density of this segment The average value of energy density is: , where E is the Young's modulus of the material; S3015: Use this small segment for energy density The average value multiplied by the length of the segment , and obtain the strain energy of this segment 1 ; S3016: Based on the above steps, the strain energies of all small segments are obtained, and the elastic potential energy of the spring system is obtained by summing the strain energies of all small segments; A printed product is obtained based on the adaptive honeycomb partitions as a printing trajectory.

2. The method according to claim 1, characterized in that S303 includes: based on the vertex coordinates of the honeycomb partitions, processing the vertices of all honeycomb partitions in sequence from one side to the other side of the area to be printed.

3. The method according to claim 2, characterized in that The vertex coordinates based on the honeycomb partitions include: comparing and screening the vertex coordinates, horizontal coordinates and vertical coordinates of all honeycomb partitions, and further determining the processing order of the vertex coordinates of all honeycomb partitions according to the sorting results.

4. The method according to any one of claims 1 to 3, characterized in that The printed product is prepared by printing using the following method, including: scanning tracks using honeycomb partitions with fixed honeycomb unit sizes.

Images