Cylindrical thin-wall part forming method

Abstract

The invention relates to the technical field of 3D printing, in particular to a cylindrical thin-wall part forming method which comprises the steps that a cylindrical thin-wall part three-dimensional model of a target size is constructed, and a scaling coefficient is integrally set to be 1 to conduct first strain analysis on the three-dimensional model; based on the length-diameter ratio of the cylindrical thin-wall part and the diameter-thickness ratio of the cylindrical thin-wall part, determining partitions in the length direction of the cylindrical thin-wall part; determining a scaling coefficient of each partition in the length direction of the cylindrical thin-wall part based on a partition result of the cylindrical thin-wall part; the size of the cylindrical thin-wall part is adjusted based on the scaling coefficient of each partition, and the final scaling coefficient of each partition is obtained based on the strain analysis result of the cylindrical thin-wall part model for multiple times; and obtaining the cylindrical thin-wall part with the target size based on the final zoom coefficient. The deformation of each area of the cylindrical thin-wall part is obviously reduced, and the size uniformity and the forming qualification rate of the cylindrical thin-wall part are improved; the problems that the diameter and the wall thickness of the barrel-type thin-wall part are not uniform, change is large, and the forming qualification rate of the barrel-type thin-wall part is low are solved.

Description

Technical Field

[0001] The present invention relates to the technical field of 3D printing, and in particular to a method for forming a cylindrical thin-walled part. Background Art

[0002] In the process of additive manufacturing to prepare large and complex thin-walled parts (part height ≥400mm, aspect ratio ≥1.5, diameter-thickness ratio ≥30), the residual stresses at different positions of the workpiece are not the same due to the extremely high temperature gradient of the molten pool solidification and the difference in thermal conductivity of the molten pool in the solid and powder. The deformation behavior of large and complex thin-walled parts is usually not overall scaling but local deformation. This nonlinear deformation based on local stress distribution is defined as non-uniform deformation. To solve the above problems, the existing technology often uses the setting of scaling factors in additive manufacturing to adjust the additive manufacturing dimensional parameters to reduce or even completely offset local deformation: Specifically for thin-walled parts, the scaling factor of thin-walled parts is the absolute value of the difference between the measured and theoretical values ​​of the thin-walled diameter and the ratio of the measured value of the thin-walled diameter plus 1.

[0003] Traditional solutions usually use a uniform scaling factor. The larger the length-to-diameter ratio of a part, the greater its non-uniform deformation will be after printing. The greater the difference in cross-sectional area, outer diameter, and wall thickness in each region in the height direction of the thin-walled part, the more difficult it is for the thin-walled part to meet the size requirements, and the molding qualification rate is low. Summary of the invention

[0004] In view of the above analysis, the present invention aims to provide a method for forming cylindrical thin-walled parts, so as to solve at least one of the problems in the prior art, such as uneven diameter and wall thickness dimensions in various regions in the height direction of cylindrical thin-walled parts, large variations, and low qualified rate of cylindrical thin-walled parts forming.

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

[0006] A method for forming a cylindrical thin-walled part, the method comprising:

[0007] S1: construct a three-dimensional model of a cylindrical thin-walled part of target size, and set the overall scaling factor to 1 to perform the first strain analysis on the three-dimensional model;

[0008] S2: Determine the partition of the cylindrical thin-walled part in the length direction based on the aspect ratio of the cylindrical thin-walled part and the diameter-thickness ratio of the cylindrical thin-walled part;

[0009] S3: Determine the scaling coefficient η of each partition in the length direction of the cylindrical thin-walled part based on the partition result in the length direction of the cylindrical thin-walled part;

[0010] S4: adjusting the size of the cylindrical thin-walled part based on the scaling coefficient η of each partition, and obtaining the final scaling coefficient η of each partition based on the strain analysis results of the cylindrical thin-walled part model before and after the adjustment of the cylindrical thin-walled part;

[0011] S5: Based on the final scaling factor η of each partition output by S4, additive manufacturing is performed to obtain a cylindrical thin-walled part of a target size.

[0012] Preferably, S4 includes:

[0013] Based on the scaling coefficient η output by S3 and the first strain analysis result, the adjusted scaling coefficient η of each partition is obtained, and it is used as the final scaling coefficient η of each partition for additive manufacturing to partition the cylindrical thin-walled part in the length direction, and different scaling coefficients are set in different partitions to reduce the deformation of each area of ​​the cylindrical thin-walled part.

[0014] Preferably, the adjusted scaling coefficient η of each partition is obtained based on the scaling coefficient η output by S3 and the first strain analysis result, and is used as the final scaling coefficient η of each partition for additive manufacturing, including:

[0015] The size of the cylindrical thin-walled part is adjusted for the first time based on the scaling coefficient η of each partition output by S3, and a second strain analysis is performed on the adjusted three-dimensional model of the cylindrical thin-walled part;

[0016] Determine the result of the second strain analysis. If the absolute value of the maximum deformation of each partition is less than or equal to a specific threshold, then output the scaling factor η of each partition output by S3 as the final scaling factor η of each partition.

[0017] If at least one of the absolute values ​​of the maximum deformation of each partition is greater than a specific threshold a, the following steps are performed;

[0018] Based on the results of the first strain analysis and the results of the second strain analysis, the scaling factor η of each partition is adjusted for the first time;

[0019] A second adjustment is made to the size of the cylindrical thin-walled part based on the scaling factor η after the first adjustment, and a third strain analysis is performed on the adjusted three-dimensional model of the cylindrical thin-walled part;

[0020] The result of the third strain analysis is judged. If the absolute value of the maximum deformation of each partition is ≤ a specific threshold, the scaling factor η adjusted for the first time is output as the final scaling factor η of each partition;

[0021] If at least one of the absolute values ​​of the maximum deformation of each partition is greater than a specific threshold value a, the scaling factor η of each partition is adjusted for the second time based on the results of the first strain analysis and the third strain analysis, the size of the cylindrical thin-walled part is adjusted for the third time based on the scaling factor η after the second adjustment, and the three-dimensional model of the cylindrical thin-walled part after the third adjustment is subjected to a fourth strain analysis;

[0022] ...repeat the above steps, and adjust the scaling factor η of each partition for the n-1th time based on the result of the first strain analysis and the result of the nth strain analysis;

[0023] Performing an nth adjustment on the size of the cylindrical thin-walled part based on the scaling factor η adjusted for the n-1th time, and performing an n+1th strain analysis on the adjusted three-dimensional model of the cylindrical thin-walled part;

[0024] Until the absolute value of the maximum deformation of each partition in the n+1th strain analysis is ≤ the specific threshold a, the scaling factor η adjusted for the n-1th time is output as the final scaling factor η of each partition.

[0025] Preferably, a=0.45 mm.

[0026] Preferably, adjusting the scaling factor η of each partition for the n-1th time based on the result of the first strain analysis and the result of the nth strain analysis includes:

[0027] S401: Obtain the result of the first strain analysis and the strain value S1 with the maximum absolute value in each region max The maximum absolute strain value Sn in the same area as the result of the nth strain analysis max ;

[0028] S402: Sn max 、S1 max The positive or negative difference δS is judged;

[0029] δS≤0, indicating that the scaling factor is too small, and there is no significant difference from the scaling factor = 0. Increase k3 by 10 times δx, where δx is the minimum step size for adjusting the scaling factor.

[0030] δS>0,

[0031] If |S1 max |>|Sn max |>a, then increase k3 by δx;

[0032] If | Sn max |>|S1 max |>a, then reduce k3 by δx;

[0033] If | Sn max |=|S1 max |>a, then reduce k3 by δx.

[0034] Preferably, δx = 0.05 × 10 -4 ~0.2×10 -4 .

[0035] Preferably, the process parameters of S5 meet the following requirements: laser power 250W-350W, scanning speed 900mm / s-1100mm / s, line spacing 0.09mm-0.12mm.

[0036] Preferably, the number N of partitions of the cylindrical thin-walled part in the length direction in S2 satisfies: N = INT[k1×k2×ln(h / φ)+(1-k1)×ln(φ / b)], wherein k1 is the distribution coefficient of the aspect ratio and the diameter-thickness ratio, k2 is the correction coefficient of the formula, h is the length of the cylindrical thin-walled part, φ is the diameter of the cylindrical thin-walled part, b is the thickness of the cylindrical thin-walled part, and INT[] represents integer operation.

[0037] Preferably, the N partitions of the cylindrical thin-walled member in the length direction are numbered in sequence from the base direction of the cylindrical thin-walled member to the top: the first partition, ..., the Nth partition, wherein the scaling factor η of the i-th partition in the length direction is i Satisfy: η i =1+(i+5)×k3×ln(φ / b), where i∈N, k3 is the correction system of the formula, φ is the diameter of the cylindrical thin-walled part, and b is the thickness of the cylindrical thin-walled part;

[0038] Based on the relation η i =1+i×k3×ln(φ / b) to obtain the scaling factor η of each partition.

[0039] Preferably, k3 = 0.9 × 10 -4 ~1.3×10 -4 .

[0040] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects:

[0041] (1) The present invention reduces the deformation of each area of ​​the cylindrical thin-walled part by dividing the cylindrical thin-walled part into sections in the length direction and setting different scaling coefficients in different sections, thereby improving the dimensional uniformity and molding qualification rate of the cylindrical thin-walled part.

[0042] (2) The present invention determines the partitioning scheme of the cylindrical thin-walled parts in the length direction based on the aspect ratio and the diameter-to-thickness ratio of the cylindrical thin-walled parts, fully considering the influence of the size and shape of the cylindrical thin-walled parts on the partitioning, and provides a more reasonable partitioning scheme, which helps to further reduce the deformation of each area of ​​the cylindrical thin-walled parts and improve the dimensional uniformity and molding qualification rate of the cylindrical thin-walled parts.

[0043] (3) The present invention determines the scaling coefficient η of each partition of the cylindrical thin-walled part in the length direction based on the diameter-to-thickness ratio of the cylindrical thin-walled part, fully considers the influence of the size and shape of the cylindrical thin-walled part on the scaling coefficient η, and provides a more reasonable scaling coefficient setting scheme, which helps to further reduce the deformation of each area of ​​the cylindrical thin-walled part and improve the dimensional uniformity and molding qualification rate of the cylindrical thin-walled part.

[0044] In the present invention, the above-mentioned technical solutions can also 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 can become obvious from the description, or can be understood by practicing the present invention. The purpose and other advantages of the present invention can be realized and obtained through the contents particularly pointed out in the embodiments of the description and the drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] The 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 components throughout the drawings.

[0046] Figure 1 It is a schematic structural diagram of a cylindrical thin-walled member of the present invention;

[0047] Figure 2 This is a simulation analysis diagram of Example 1;

[0048] Figure 3 This is a simulation analysis diagram of Comparative Example 1;

[0049] Figure 4 This is a simulation analysis diagram for comparative example 2. DETAILED DESCRIPTION

[0050] The preferred embodiments of the present invention will be described in detail below in conjunction with 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.

[0051] It should be noted that the thin-walled member of the present invention, such as Figure 1 As shown, it is a cylindrical thin-walled part with a part length ≥400mm, a length-to-diameter ratio ≥1.5, and a diameter-to-thickness ratio ≥30. The thickness b of the thin-walled part body is much smaller than the diameter φ and length h of the thin-walled part.

[0052] In one aspect, the present invention discloses a method for forming a cylindrical thin-walled part, comprising:

[0053] S1: construct a three-dimensional model of a cylindrical thin-walled part of target size, and set the overall scaling factor to 1 to perform the first strain analysis on the three-dimensional model;

[0054] S2: Determine the partition of the cylindrical thin-walled part in the length direction based on the aspect ratio of the cylindrical thin-walled part and the diameter-thickness ratio of the cylindrical thin-walled part;

[0055] S3: Determine the scaling coefficient η of each partition in the length direction of the cylindrical thin-walled part based on the partition result in the length direction of the cylindrical thin-walled part;

[0056] S4: adjusting the size of the cylindrical thin-walled part based on the scaling coefficient η of each partition, and obtaining the final scaling coefficient η of each partition based on the strain analysis results of the cylindrical thin-walled part model before and after the adjustment of the cylindrical thin-walled part;

[0057] S5: Based on the final scaling factor η of each partition output by S4, additive manufacturing is performed to obtain a cylindrical thin-walled part of a target size.

[0058] It should be noted that additive manufacturing grows layer by layer from the substrate; the substrate is fixed, so its scaling is limited; as it goes up along the length direction of the cylindrical thin-walled part, in the state of the free end, its shrinkage deformation will be released more; at the same time, with the increase of height, stress is gradually accumulated, which causes the stress to increase and the shrinkage to increase, and the scaling coefficient to increase as the length direction of the cylindrical thin-walled part goes up.

[0059] Compared with the prior art, the present invention reduces the deformation of each area of ​​the cylindrical thin-walled part by dividing the cylindrical thin-walled part into zones in the length direction and setting different scaling coefficients in different zones, thereby improving the dimensional uniformity and molding qualification rate of the cylindrical thin-walled part.

[0060] Specifically, S2 includes:

[0061] The larger the aspect ratio and the diameter-to-thickness ratio, the larger the number of partitions N of the cylindrical thin-walled part in the length direction.

[0062] The applicant has found that the deformation distribution of the length direction of the cylindrical thin-walled part is related to the size of the cylindrical thin-walled part. The higher the axial direction of the cylindrical thin-walled part and the thinner the wall thickness, the smaller the rigidity of the cylindrical thin-walled part, the worse the ability of the top end of the cylindrical thin-walled part to resist shrinkage, and the easier it is to shrink and deform.

[0063] Specifically, the number N of partitions of the cylindrical thin-walled part in the length direction satisfies: N = INT[k1×k2×ln(h / φ)+(1-k1)×ln(φ / b)], wherein k1 is the distribution coefficient of the aspect ratio and the diameter-thickness ratio, k2 is the correction coefficient of the formula, h is the length of the cylindrical thin-walled part, φ is the diameter of the cylindrical thin-walled part, b is the thickness of the cylindrical thin-walled part, and INT[] represents integer operation.

[0064] Specifically, the value of k1 is 0.9-1.0, and the value of k2 is 8-12.

[0065] Preferably, the cylindrical thin-walled member is divided into equal-length partitions in the length direction, that is, the lengths of the partitions are the same.

[0066] Compared with the prior art, the present invention provides a more reasonable zoning scheme by determining the zoning scheme of the cylindrical thin-walled parts in the length direction based on the aspect ratio and the diameter-to-thickness ratio of the cylindrical thin-walled parts, fully considering the influence of the size and shape of the cylindrical thin-walled parts on the zoning, and helping to further reduce the deformation of each area of ​​the cylindrical thin-walled parts and improve the dimensional uniformity and molding qualification rate of the cylindrical thin-walled parts.

[0067] Specifically, S3 includes:

[0068] The N partitions of the cylindrical thin-walled part in the length direction are numbered in sequence from the base direction of the cylindrical thin-walled part to the top: the first partition, ..., the Nth partition, where the scaling factor η of the i-th partition in the length direction is i Satisfy: η i =1+(i+5)×k3×ln(φ / b), where i∈N and k3 is the correction factor of the formula;

[0069] Based on the relation η i =1+i×k3×ln(φ / b) to obtain the scaling factor η of each partition.

[0070] Specifically, k3 can be selected as 0.9×10 -4 ~1.3×10 -4 .

[0071] It should be noted that the strain of the partition of the cylindrical thin-walled part in the length direction gradually increases from the base direction to the top end, and the corresponding scaling coefficient η should be appropriately increased; the applicant's research found that the scaling coefficient η is also affected by the diameter-to-thickness ratio φ / b of the cylindrical thin-walled part, and the scaling coefficient η of the cylindrical thin-walled part with a larger diameter-to-thickness ratio should be appropriately increased.

[0072] Preferably, the scaling coefficient η of each partition of the cylindrical thin-walled part in the length direction is 1.003-1.005, the interval between adjacent partitions is 0.0005, and the scaling coefficient η of each partition can be 1.003, 1.0035, 1.004, 1.0045 or 1.005.

[0073] Compared with the prior art, the present invention provides a more reasonable scaling factor setting scheme by determining the scaling coefficient η of each partition of the cylindrical thin-walled part in the length direction based on the diameter-to-thickness ratio of the cylindrical thin-walled part, fully considering the influence of the size and shape of the cylindrical thin-walled part on the scaling coefficient η, and helping to further reduce the deformation of each area of ​​the cylindrical thin-walled part and improve the dimensional uniformity and molding qualification rate of the cylindrical thin-walled part.

[0074] Specifically, S4 includes:

[0075] Based on the scaling coefficient η output by S3 and the first strain analysis result, the adjusted scaling coefficient η of each partition is obtained, and it is used as the final scaling coefficient η of each partition for additive manufacturing to partition the cylindrical thin-walled part in the length direction, and different scaling coefficients are set in different partitions to reduce the deformation of each area of ​​the cylindrical thin-walled part.

[0076] Specifically, based on the scaling factor η output by S3 and the first strain analysis result, the adjusted scaling factor η of each partition is obtained, and it is used as the final scaling factor η of each partition for additive manufacturing, including:

[0077] The size of the cylindrical thin-walled part is adjusted for the first time based on the scaling coefficient η of each partition output by S3, and a second strain analysis is performed on the adjusted three-dimensional model of the cylindrical thin-walled part;

[0078] Determine the result of the second strain analysis. If the absolute value of the maximum deformation of each partition is less than or equal to a specific threshold, then output the scaling factor η of each partition output by S3 as the final scaling factor η of each partition.

[0079] If at least one of the absolute values ​​of the maximum deformation of each partition is greater than a specific threshold a, the following steps are performed;

[0080] Based on the results of the first strain analysis and the results of the second strain analysis, the scaling factor η of each partition is adjusted for the first time;

[0081] A second adjustment is made to the size of the cylindrical thin-walled part based on the scaling factor η after the first adjustment, and a third strain analysis is performed on the adjusted three-dimensional model of the cylindrical thin-walled part;

[0082] The result of the third strain analysis is judged. If the absolute value of the maximum deformation of each partition is ≤ a specific threshold, the scaling factor η adjusted for the first time is output as the final scaling factor η of each partition;

[0083] If at least one of the absolute values ​​of the maximum deformation of each partition is greater than a specific threshold value a, the scaling factor η of each partition is adjusted for the second time based on the results of the first strain analysis and the third strain analysis, the size of the cylindrical thin-walled part is adjusted for the third time based on the scaling factor η after the second adjustment, and the three-dimensional model of the cylindrical thin-walled part after the third adjustment is subjected to a fourth strain analysis;

[0084] ...repeat the above steps, and adjust the scaling factor η of each partition for the n-1th time based on the result of the first strain analysis and the result of the nth strain analysis;

[0085] Performing an nth adjustment on the size of the cylindrical thin-walled part based on the scaling factor η adjusted for the n-1th time, and performing an n+1th strain analysis on the adjusted three-dimensional model of the cylindrical thin-walled part;

[0086] Until the absolute value of the maximum deformation of each partition in the n+1th strain analysis is ≤ the specific threshold a, the scaling factor η adjusted for the n-1th time is output as the final scaling factor η of each partition.

[0087] Specifically, a may be 0.45 mm.

[0088] Specifically, adjusting the scaling factor η of each partition for the n-1th time based on the result of the first strain analysis and the result of the nth strain analysis includes:

[0089] S401: Obtain the result of the first strain analysis and the strain value S1 with the maximum absolute value in each region max The maximum absolute strain value Sn in the same area as the result of the nth strain analysis max ;

[0090] S402: Sn max 、S1 max The positive or negative difference δS is judged;

[0091] δS≤0, indicating that the scaling factor is too small, and there is no significant difference from the scaling factor = 0. Increase k3 by 10 times δx, where δx is the minimum step size for adjusting the scaling factor.

[0092] δS>0,

[0093] If |S1 max |>|Sn max |>a, then increase k3 by δx;

[0094] If | Sn max |>|S1 max |>a, then reduce k3 by δx;

[0095] If | Sn max |=|S1 max |>a, then reduce k3 by δx.

[0096] Specifically, δx can be 0.05×10 -4 ~0.2×10 -4 .

[0097] Specifically, S5 additive manufacturing uses 3D printing technology.

[0098] Specifically, the process parameters of the 3D printing process meet the following requirements: laser power 250W to 350W, scanning speed 900mm / s to 1100mm / s, and line spacing 0.09mm to 0.12mm.

[0099] During implementation, the scaling factor η can be input into the operating interface of the additive manufacturing software together with parameters such as laser power.

[0100] In order to further illustrate the present invention, the following examples and comparative examples are provided:

[0101] Example 1

[0102] This embodiment discloses a method for forming a cylindrical thin-walled part, comprising:

[0103] S1: construct a three-dimensional model of a cylindrical thin-walled part of target size, with a length h of 450 mm, a part diameter φ of 300 mm, a part wall thickness φ of 5 mm, and set the overall scaling factor = 1 to perform the first strain analysis on the three-dimensional model;

[0104] S2: Determine the partitions of the cylindrical thin-walled part in the length direction based on the aspect ratio and the diameter-thickness ratio of the cylindrical thin-walled part; the number of partitions N of the cylindrical thin-walled part in the length direction satisfies: N=INT[k1×k2×ln(h / φ)+(1-k1)×ln(φ / b)]=5, k1=0.9, k2=10.

[0105] S3: Based on η i =1+(i+5)×k3×ln(φ / b), and obtain the scaling factor η of each partition, k3=1.22×10 -4 , the scaling factor η of each partition is 1.003, 1.0035, 1.004, 1.0045, and 1.005 from bottom to top;

[0106] S4: adjusting the size of the cylindrical thin-walled part based on the scaling factor η, and obtaining the final scaling factor η of each partition based on the strain analysis results of the cylindrical thin-walled part model before and after the adjustment of the cylindrical thin-walled part;

[0107] The size of the cylindrical thin-walled part is adjusted for the first time based on the scaling coefficient η of each partition output by S3, and a second strain analysis is performed on the adjusted three-dimensional model of the cylindrical thin-walled part;

[0108] Determine the result of the second strain analysis. If the absolute value of the maximum deformation of each partition is less than or equal to a specific threshold, then output the scaling factor η of each partition output by S3 as the final scaling factor η of each partition.

[0109] If at least one of the absolute values ​​of the maximum deformation of each partition is greater than a specific threshold a, the following steps are performed;

[0110] Based on the results of the first strain analysis and the results of the second strain analysis, the scaling factor η of each partition is adjusted for the first time;

[0111] A second adjustment is made to the size of the cylindrical thin-walled part based on the scaling factor η after the first adjustment, and a third strain analysis is performed on the adjusted three-dimensional model of the cylindrical thin-walled part;

[0112] The result of the third strain analysis is judged. If the absolute value of the maximum deformation of each partition is ≤ a specific threshold, the scaling factor η adjusted for the first time is output as the final scaling factor η of each partition;

[0113] If at least one of the absolute values ​​of the maximum deformation of each partition is greater than a specific threshold value a, the scaling factor η of each partition is adjusted for the second time based on the results of the first strain analysis and the third strain analysis, the size of the cylindrical thin-walled part is adjusted for the third time based on the scaling factor η after the second adjustment, and the three-dimensional model of the cylindrical thin-walled part after the third adjustment is subjected to a fourth strain analysis;

[0114] ...repeat the above steps, and adjust the scaling factor η of each partition for the n-1th time based on the result of the first strain analysis and the result of the nth strain analysis;

[0115] Performing an nth adjustment on the size of the cylindrical thin-walled part based on the scaling factor η adjusted for the n-1th time, and performing an n+1th strain analysis on the adjusted three-dimensional model of the cylindrical thin-walled part;

[0116] Until the absolute value of the maximum deformation of each partition in the n+1th strain analysis is ≤ the specific threshold a, the scaling factor η adjusted for the n-1th time is output as the final scaling factor η of each partition.

[0117] a=0.45mm.

[0118] In S4, the scaling factor η of each partition is adjusted for the n-1th time based on the result of the first strain analysis and the result of the nth strain analysis, including:

[0119] S401: Obtain the result of the first strain analysis and the strain value S1 with the maximum absolute value in each region max The maximum absolute strain value Sn in the same area as the result of the nth strain analysis max ;

[0120] S402: Sn max 、S1 max The positive or negative difference δS is judged;

[0121] δS≤0, indicating that the scaling factor is too small, and there is no significant difference from the scaling factor = 1. Increase k3 by 10 times δx, where δx is the minimum step size for adjusting the scaling factor.

[0122] δS>0,

[0123] If |S1 max |>|Sn max |>a, then increase k3 by δx;

[0124] If | Sn max |>|S1max |>a, then reduce k3 by δx;

[0125] If | Sn max |=|S1 max |>a, then reduce k3 by δx.

[0126] δx=0.1×10 -4 .

[0127] S5: The final scaling factor η of each partition output by S4 is used for preparing a cylindrical thin-walled part by a 3D printing process, and the 3D printing process parameters meet the following requirements: laser power 250 W, scanning speed 900 mm / s, and line spacing 0.09 mm.

[0128] The simulation analysis results of the strains at various locations of the cylindrical thin-walled part prepared in this embodiment are as follows: Figure 2 As shown: the absolute value of strain at each location is ≤0.45mm, and the strain is relatively uniform.

[0129] Example 2

[0130] This embodiment discloses a method for forming a cylindrical thin-walled part, comprising:

[0131] S1: construct a three-dimensional model of a cylindrical thin-walled part of target size, with a length h of 500 mm, a part diameter φ of 300 mm, a part wall thickness φ of 6 mm, and set the overall scaling factor = 1 to perform the first strain analysis on the three-dimensional model;

[0132] S2: Determine the partitions of the cylindrical thin-walled part in the length direction based on the aspect ratio and the diameter-thickness ratio of the cylindrical thin-walled part; the number of partitions N of the cylindrical thin-walled part in the length direction satisfies: N=INT[k1×k2×ln(h / φ)+(1-k1)×ln(φ / b)]=5, k1=0.9, k2=11.

[0133] S3: Based on η i =1+(i+5)×k3×ln(φ / b), and obtain the scaling factor η of each partition, k3=1.278×10 -4 , the scaling factor η of each partition is 1.003, 1.0035, 1.004, 1.0045, and 1.005 from bottom to top;

[0134] S4: adjusting the size of the cylindrical thin-walled part based on the scaling factor η, and obtaining the final scaling factor η of each partition based on the strain analysis results of the cylindrical thin-walled part model before and after the adjustment of the cylindrical thin-walled part;

[0135] The size of the cylindrical thin-walled part is adjusted for the first time based on the scaling coefficient η of each partition output by S3, and a second strain analysis is performed on the adjusted three-dimensional model of the cylindrical thin-walled part;

[0136] Determine the result of the second strain analysis. If the absolute value of the maximum deformation of each partition is less than or equal to a specific threshold, then output the scaling factor η of each partition output by S3 as the final scaling factor η of each partition.

[0137] If at least one of the absolute values ​​of the maximum deformation of each partition is greater than a specific threshold a, the following steps are performed;

[0138] Based on the results of the first strain analysis and the results of the second strain analysis, the scaling factor η of each partition is adjusted for the first time;

[0139] A second adjustment is made to the size of the cylindrical thin-walled part based on the scaling factor η after the first adjustment, and a third strain analysis is performed on the adjusted three-dimensional model of the cylindrical thin-walled part;

[0140] The result of the third strain analysis is judged. If the absolute value of the maximum deformation of each partition is ≤ a specific threshold, the scaling factor η adjusted for the first time is output as the final scaling factor η of each partition;

[0141] If at least one of the absolute values ​​of the maximum deformation of each partition is greater than a specific threshold value a, the scaling factor η of each partition is adjusted for the second time based on the results of the first strain analysis and the third strain analysis, the size of the cylindrical thin-walled part is adjusted for the third time based on the scaling factor η after the second adjustment, and the three-dimensional model of the cylindrical thin-walled part after the third adjustment is subjected to a fourth strain analysis;

[0142] ...repeat the above steps, and adjust the scaling factor η of each partition for the n-1th time based on the result of the first strain analysis and the result of the nth strain analysis;

[0143] Performing an nth adjustment on the size of the cylindrical thin-walled part based on the scaling factor η adjusted for the n-1th time, and performing an n+1th strain analysis on the adjusted three-dimensional model of the cylindrical thin-walled part;

[0144] Until the absolute value of the maximum deformation of each partition in the n+1th strain analysis is ≤ the specific threshold a, the scaling factor η adjusted for the n-1th time is output as the final scaling factor η of each partition.

[0145] a=0.45mm.

[0146] In S4, the scaling factor η of each partition is adjusted for the n-1th time based on the result of the first strain analysis and the result of the nth strain analysis, including:

[0147] S401: Obtain the result of the first strain analysis and the strain value S1 with the maximum absolute value in each region max The maximum absolute strain value Sn in the same area as the result of the nth strain analysis max ;

[0148] S402: Sn max 、S1 max The positive or negative difference δS is judged;

[0149] δS≤0, indicating that the scaling factor is too small, and there is no significant difference from the scaling factor = 0. Increase k3 by 10 times δx, where δx is the minimum step size for adjusting the scaling factor.

[0150] δS>0,

[0151] If |S1 max |>|Sn max |>a, then increase k3 by δx;

[0152] If | Sn max |>|S1 max |>a, then reduce k3 by δx;

[0153] If | Sn max |=|S1 max |>a, then reduce k3 by δx.

[0154] δx=0.1×10 -4 .

[0155] S5: The final scaling factor η of each partition output by S4 is used for preparing a cylindrical thin-walled part by a 3D printing process. The 3D printing process parameters meet the following requirements: laser power 350 W, scanning speed 1000 mm / s, and line spacing 0.12 mm.

[0156] The strain at various locations of the cylindrical thin-walled part prepared in this embodiment is simulated and analyzed: the absolute value of the strain at various locations is ≤0.48 mm, and the strain is relatively uniform.

[0157] Comparative Example 1

[0158] This comparative example discloses a method for forming a cylindrical thin-walled part. The difference from Example 1 is that when the cylindrical thin-walled part is prepared by 3D printing process, the scaling factor is set to 1, and the rest is the same as Example 1.

[0159] The simulation analysis results of the strains at various locations of the cylindrical thin-walled parts prepared in this comparative example are as follows: Figure 3 As shown: the maximum absolute value of strain at each location is 1.43 mm, which is much larger than that in Example 1.

[0160] Comparative Example 2

[0161] This comparative example discloses a method for forming a cylindrical thin-walled part. The difference from Example 1 is that when the cylindrical thin-walled part is prepared by 3D printing process, the scaling coefficient of each partition is set to 1.003, and the rest is the same as Example 1.

[0162] The simulation analysis results of the strains at various locations of the cylindrical thin-walled parts prepared in this comparative example are as follows: Figure 4 As shown: the maximum absolute value of strain at each location is 0.69 mm, which is much larger than that in Example 1.

[0163] Comparative Example 3

[0164] This comparative example discloses a method for forming a cylindrical thin-walled part. The difference from Example 1 is that when the cylindrical thin-walled part is prepared by 3D printing process, the scaling coefficients of each partition are set to 1.001, 1.004, 1.008, 1.010, and 1.0012 from bottom to top, which does not meet the requirements of η i =1+(i+5)×k3×ln(φ / b), and the rest is the same as in Example 1.

[0165] The strains at various locations of the cylindrical thin-walled part prepared in this comparative example were simulated and analyzed: the maximum absolute value of the strain at various locations was 0.63 mm, which was much larger than that of Example 1.

[0166] By comparing Examples 1 to 2 and Comparative Examples 1 and 2, it can be seen that the absolute values ​​of the maximum strains at various locations of the cylindrical thin-walled parts prepared in Examples 1 / 2 of the present invention are between 0.43 mm and 0.45 mm, which are much smaller than Comparative Examples 1 and 2. This indicates that relative to the prior art scaling with the same scaling factor, the present invention can greatly improve the problems of uneven diameters and wall thicknesses in various regions in the height direction of cylindrical thin-walled parts, large variations, and low molding qualification rate of cylindrical thin-walled parts by scaling by partitions and adopting a preferred method to give scaling factors for each region.

[0167] Further, by comparing Example 1 and Comparative Example 3, it can be seen that the scaling factor of each partition is η i =1+(i+5)×k3×ln(φ / b) The setting that is less in line with this rule can greatly improve the problems of uneven diameters and wall thicknesses in various regions along the height direction of cylindrical thin-walled parts, large variations, and low molding qualification rate of cylindrical thin-walled parts.

[0168] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by any technician familiar with the technical field within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention.

Claims

1. A method for forming a cylindrical thin-walled part, characterized in that: The molding method comprises: S1: construct a three-dimensional model of a cylindrical thin-walled part of target size, and set the overall scaling factor to 1 to perform the first strain analysis on the three-dimensional model; S2: Determine the partition of the cylindrical thin-walled part in the length direction based on the aspect ratio of the cylindrical thin-walled part and the diameter-thickness ratio of the cylindrical thin-walled part; S3: Determine the scaling coefficient η of each partition in the length direction of the cylindrical thin-walled part based on the partition result in the length direction of the cylindrical thin-walled part; S4: adjusting the size of the cylindrical thin-walled part based on the scaling coefficient η of each partition, and obtaining the final scaling coefficient η of each partition based on the strain analysis results of the cylindrical thin-walled part model before and after the adjustment of the cylindrical thin-walled part; S5: Based on the final scaling factor η of each partition output by S4, additive manufacturing is performed to obtain a cylindrical thin-walled part of a target size.

2. The method for forming a cylindrical thin-walled part according to claim 1, characterized in that: S4 includes: Based on the scaling coefficient η output by S3 and the first strain analysis result, the adjusted scaling coefficient η of each partition is obtained, and it is used as the final scaling coefficient η of each partition for additive manufacturing to partition the cylindrical thin-walled part in the length direction, and different scaling coefficients are set in different partitions to reduce the deformation of each area of ​​the cylindrical thin-walled part.

3. The method for forming a cylindrical thin-walled part according to claim 2, characterized in that: Based on the scaling factor η output by S3 and the first strain analysis result, the adjusted scaling factor η of each partition is obtained, and it is used as the final scaling factor η of each partition for additive manufacturing, including: The size of the cylindrical thin-walled part is adjusted for the first time based on the scaling coefficient η of each partition output by S3, and a second strain analysis is performed on the adjusted three-dimensional model of the cylindrical thin-walled part; Determine the result of the second strain analysis. If the absolute value of the maximum deformation of each partition is less than or equal to a specific threshold, then output the scaling factor η of each partition output by S3 as the final scaling factor η of each partition. If at least one of the absolute values ​​of the maximum deformation of each partition is greater than a specific threshold a, the following steps are performed; Based on the results of the first strain analysis and the results of the second strain analysis, the scaling factor η of each partition is adjusted for the first time; A second adjustment is made to the size of the cylindrical thin-walled part based on the scaling factor η after the first adjustment, and a third strain analysis is performed on the adjusted three-dimensional model of the cylindrical thin-walled part; The result of the third strain analysis is judged. If the absolute value of the maximum deformation of each partition is ≤ a specific threshold, the scaling factor η adjusted for the first time is output as the final scaling factor η of each partition; If at least one of the absolute values ​​of the maximum deformation of each partition is greater than a specific threshold value a, the scaling factor η of each partition is adjusted for the second time based on the results of the first strain analysis and the third strain analysis, the size of the cylindrical thin-walled part is adjusted for the third time based on the scaling factor η after the second adjustment, and the three-dimensional model of the cylindrical thin-walled part after the third adjustment is subjected to a fourth strain analysis; ...repeat the above steps, and adjust the scaling factor η of each partition for the n-1th time based on the result of the first strain analysis and the result of the nth strain analysis; Performing an nth adjustment on the size of the cylindrical thin-walled part based on the scaling factor η adjusted for the n-1th time, and performing an n+1th strain analysis on the adjusted three-dimensional model of the cylindrical thin-walled part; Until the absolute value of the maximum deformation of each partition in the n+1th strain analysis is ≤ the specific threshold a, the scaling factor η adjusted for the n-1th time is output as the final scaling factor η of each partition.

4. The method for forming a cylindrical thin-walled part according to claim 3, characterized in that: a=0.45mm.

5. The method for forming a cylindrical thin-walled part according to claim 3, characterized in that: The scaling factor η of each partition is adjusted for the n-1th time based on the result of the first strain analysis and the result of the nth strain analysis, including: S401: Obtain the result of the first strain analysis and the strain value S1 with the maximum absolute value in each region max The maximum absolute strain value Sn in the same area as the result of the nth strain analysis max ; S402: Sn max 、S1 max The positive or negative difference δS is judged; δS≤0, indicating that the scaling factor is too small, and there is no significant difference from the scaling factor = 0. Increase k3 by 10 times δx, where δx is the minimum step size for adjusting the scaling factor. δS>0, If |S1 max |>|Sn max |>a, then increase k3 by δx; If | Sn max |>|S1 max |>a, then reduce k3 by δx; If | Sn max |=|S1 max |>a, then reduce k3 by δx.

6. The method for forming a cylindrical thin-walled part according to claim 5, characterized in that: δx=0.05×10 -4 ~0.2×10 -4 。 7. The method for forming a cylindrical thin-walled part according to claim 1, characterized in that: The process parameters of S5 meet the following requirements: laser power 250W~350W, scanning speed 900mm / s~1100mm / s, line spacing 0.09mm~0.12mm.

8. The method for forming a cylindrical thin-walled part according to claim 1, characterized in that: The number N of partitions of the cylindrical thin-walled part in the length direction in S2 satisfies: N = INT[k1×k2×ln(h / φ)+(1-k1)×ln(φ / b)], wherein k1 is the distribution coefficient of the aspect ratio and the diameter-thickness ratio, k2 is the correction coefficient of the formula, h is the length of the cylindrical thin-walled part, φ is the diameter of the cylindrical thin-walled part, b is the thickness of the cylindrical thin-walled part, and INT[] represents integer operation.

9. The method for forming a cylindrical thin-walled part according to any one of claims 1 to 8, characterized in that: The N partitions of the cylindrical thin-walled part in the length direction are numbered in sequence from the base direction of the cylindrical thin-walled part to the top: the first partition, ..., the Nth partition, where the scaling factor η of the i-th partition in the length direction is i Satisfy: η i =1+(i+5)×k3×ln(φ / b), where i∈N, k3 is the correction system of the formula, φ is the diameter of the cylindrical thin-walled part, and b is the thickness of the cylindrical thin-walled part; Based on the relation η i =1+i×k3×ln(φ / b) to obtain the scaling factor η of each partition.

10. The method for forming a cylindrical thin-walled part according to claim 9, characterized in that: k3＝0.9×10 -4 ～1.3×10 -4 。

Images