An additively manufactured one-piece prosthetic decorative shell and its manufacturing process

Abstract

This invention relates to the technical field of medical devices, and in particular to an additive manufacturing process for a one-piece prosthetic decorative shell and its fabrication. The fabrication process includes scanning and modeling, model conversion, printing, and post-processing. By precisely controlling the printing speed, printing temperature, printing thickness, and layer height, this invention ensures that each layer of material rapidly fuses with the printed layers within a reasonable melting time. This technology significantly reduces interlayer gaps, achieving seamless one-piece molding. This invention not only improves printing efficiency but also ensures the integrity and quality of the product; the printed product is less prone to breakage or damage, and it provides better surface smoothness while maintaining a relatively fast printing speed.

Description

Technical Field

[0001] This invention relates to the technical field of medical devices, and in particular to an additive manufacturing process for an integrally molded prosthetic decorative shell. Background Technology

[0002] Lower leg prostheses are generally skeletal in structure, meaning the prosthesis socket and footplate are connected by a metal tube. However, the metal tube differs greatly from the shape of the human leg, resulting in a noticeable gap in the pant leg when worn, which can easily cause patients to feel uncomfortable.

[0003] Currently, the market generally uses cylindrical sponge or molded foam materials to create an outer shell that mimics the shape of the leg, encasing a metal tube inside, and then fitting it onto the lower leg prosthesis. However, this outer shell relies on manual polishing and is glued together. As a result, the shell has poor fit, a rough surface, and lacks aesthetic appeal. Furthermore, shells made of sponge or foam materials have poor flexibility, are not waterproof, are easily damaged and prone to breakage, have poor surface elasticity, and a short lifespan.

[0004] Therefore, the existing technology lacks a decorative shell for a lower leg prosthesis that is smooth, flexible, durable, and not prone to breakage. Summary of the Invention

[0005] To address the aforementioned deficiencies or improvement needs of existing technologies, this invention provides a prosthetic decorative shell. Its purpose is to provide a prosthetic shell with a smooth surface and high flexibility, thereby solving the technical problems of poor flexibility, rough surface, and susceptibility to breakage in existing prosthetic decorative shells. The detailed technical solution of this invention is described below.

[0006] This invention protects a manufacturing process for an additively manufactured one-piece prosthetic decorative shell, comprising the following steps:

[0007] S1. Scanning and Modeling: Using a medical 3D scanner, the patient's prosthetic lower leg and healthy lower leg in an upright position are scanned and modeled to obtain a 3D image data model.

[0008] S2. Model Conversion: Using 3D software, the 3D image data model is processed for data model fitting and simulation line analysis, and converted into a 3D printing data model for the decorative shell of the lower leg prosthesis.

[0009] S3. Printing: Import the 3D printing data model into the additive manufacturing slicing software, set the additive manufacturing printing parameters, and send it to the additive manufacturing equipment for 3D printing to obtain a one-piece molded lower leg prosthesis decorative shell semi-finished product.

[0010] S4. Post-processing: The semi-finished decorative shell of the lower leg prosthesis is cut and surface inspection and testing are carried out. After the inspection and testing are qualified, the finished decorative shell of the lower leg prosthesis is obtained.

[0011] Preferably, the printing parameters in step S3 include printing speed x. v Printing temperature x t Printing thickness x d and floor height x h By controlling the printing speed, printing temperature, printing thickness, and layer height of the material, each newly printed layer can be rapidly fused with the already printed layers within the melting time.

[0012] Preferably, the normalized printing parameters in step S3 are used to obtain the normalized printing speed value x. v Printing temperature normalization value x t Print thickness normalization value x d and floor height normalization value x h ,

[0013]

[0014] e is the base of the natural logarithm. When both P1 and P2 are greater than 50%, a shaped product can be obtained.

[0015] Preferably, the medical 3D scanner in step S1 is any one of a composite 3D scanner, a 3D laser scanner, or a smart blue light handheld scanner.

[0016] Preferably, the 3D software in step S2 is any one of UG, Solidworks, CAD, or Creo; and the additive manufacturing slicing software in step S3 is any one of KISSlicer, ideaMaker, OctoPrint, or 3DPrinterOS.

[0017] Preferably, the additive manufacturing equipment in step S3 is any one of SLA, SLM, SLS, FGF or FDM.

[0018] Preferably, the semi-finished decorative shell of the lower leg prosthesis in step S3 is made of thermoplastic polyurethane rubber material.

[0019] The present invention also protects a prosthetic decorative shell made using the manufacturing process described in any one of the foregoing claims, comprising an upper cavity and a lower cavity, wherein a receiving cavity connecting device is provided at the top of the upper cavity, a first nesting ring is provided at the bottom of the upper cavity, a second nesting ring is provided at the top of the lower cavity, the first nesting ring and the second nesting ring are detachably and fixedly connected, and a footplate shell connecting device is provided at the bottom of the lower cavity.

[0020] The first beneficial effect of this invention is its ability to achieve seamless, one-piece printing. Traditional 3D printing technology is often limited by the layer-by-layer deposition of material, easily leading to gaps or weak bonding between layers. This invention, however, precisely controls the printing speed, temperature, thickness, and layer height, ensuring that each layer rapidly fuses with the previous layer within a reasonable melting time. All four parameters are indispensable. This invention significantly reduces interlayer gaps, thus achieving truly seamless, one-piece printing. This remarkable feature not only improves printing efficiency but also ensures the integrity and quality of the finished product.

[0021] The second beneficial effect of this invention is the ability to achieve a smooth surface through one-piece molding, reducing roughness. Once a product is manufactured, it cannot be sanded. Sanding will cause damage, create surface burrs, and increase surface roughness, reducing structural strength. Therefore, all existing products, if their surface smoothness cannot be controlled, suffer from compromised overall quality and functionality, resulting in a poor user experience. This invention, through a digital solution, precisely matches printing speed, printing temperature, printing thickness, and layer height, improving its mechanical strength and durability, making it less prone to breakage or damage, and providing better surface smoothness while maintaining a relatively fast printing speed. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the overall structure of the present invention;

[0023] Figure 2 This is a schematic diagram of the upper cavity of the present invention;

[0024] Figure 3 This is a schematic diagram of the lower cavity of the present invention;

[0025] Figure 4 These are photographs of the qualified finished product of the upper cavity of this invention;

[0026] Figure 5 This is a photograph of a defective product of the present invention whose surface roughness of the upper cavity is substandard.

[0027] Figure 6 This is a photograph of a defective product with substandard wire spacing in the upper cavity of the present invention.

[0028] Figure 7 This is a graph showing the linear relationship between printing speed and printing temperature in this invention.

[0029] Figure 8 This is a linear relationship diagram of the printing thickness and layer height data of this invention.

[0030] In the figure: 1. Upper cavity; 1-1. Receiving cavity connecting device; 1-2. First nested ring; 2. Lower cavity; 2-1. Second nested ring; 2-2. Foot plate outer shell connecting device. Detailed Implementation

[0031] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0032] Example

[0033] The manufacturing process of the prosthetic decorative shell of the present invention includes the following steps:

[0034] S1. Scanning and Modeling: Using a medical 3D scanner, the patient's lower leg prosthesis and the healthy lower leg in an upright position are scanned and modeled to obtain a 3D image data model.

[0035] S2. Model Conversion: Using 3D software, the 3D image data model is processed for data model fitting and simulation line analysis, and converted into a 3D printing data model for the decorative shell of the lower leg prosthesis.

[0036] S3. Printing: Import the 3D printing data model into the additive manufacturing slicing software, set the additive manufacturing printing parameters, and send it to the additive manufacturing equipment for 3D printing to obtain a one-piece molded lower leg prosthesis decorative shell semi-finished product.

[0037] S4. Post-processing: The semi-finished decorative shell of the lower leg prosthesis is cut and the surface is inspected.

[0038] The prosthetic decorative shell prepared based on the manufacturing process described in the embodiments of the present invention, such as... Figure 1 — Figure 3 As shown, it includes an upper cavity 1 and a lower cavity 2. The top of the upper cavity 1 is provided with a receiving cavity connecting device 1-1, the bottom of the upper cavity 1 is provided with a first nesting ring 1-2, the top of the lower cavity 2 is provided with a second nesting ring 2-1, the first nesting ring 1-2 and the second nesting ring 2-1 are detachably fixedly connected, and the bottom of the lower cavity 2 is provided with a foot plate outer shell connecting device 2-2.

[0039] The following section will further elaborate on the specific printing method.

[0040] Example 1

[0041] In this embodiment, the prosthetic decorative shell is printed using TPU material. TPU material possesses unique properties, combining the processability of thermoplastics with the flexibility of elastomers, thus exhibiting strong adaptability. Due to the characteristics of TPU, the printing temperature should be maintained between 210°C and 250°C during the printing process. Within this temperature range, the material maintains good fluidity, avoiding blockage or stringing caused by excessively low temperatures, or melting and accumulation caused by excessively high temperatures.

[0042] The printing speed for TPU is set between 20mm / s and 40mm / s. By slowing down the printing speed, printing accuracy can be improved and material stringing can be reduced, thereby improving print quality.

[0043] S1. Scanning and Modeling: A medical 3D scanner is used to scan and model the lower leg prosthesis, obtaining a 3D image data model of the lower leg prosthesis, including the lower leg socket, connectors, metal connecting tubes, prosthetic footplate, and the assembled prosthetic foot skin; then, the lower leg of the healthy side of the patient is scanned and modeled to obtain a 3D image data model of the healthy lower leg, which is used to help establish the outline of the decorative shell of the lower leg prosthesis;

[0044] S2. Model Conversion: Prosthetic technicians use UG 3D software to perform data model fitting and simulation line analysis on the image model of the lower leg prosthesis and the data model of the healthy lower leg. Based on the fitted data model and biomechanics, a 3D printing data model of the decorative shell of the lower leg prosthesis is established.

[0045] S3. Printing: Import the additive manufacturing slicing software, set the additive manufacturing printing parameters, including printing speed of 40mm / s, printing temperature of 225℃, printing thickness of 2.6mm, layer height of 0.4mm, and send it to the additive manufacturing equipment for 3D printing to obtain a one-piece molded lower leg prosthesis decorative shell semi-finished product.

[0046] S4. Post-processing: After printing, allow the semi-finished product to cool naturally, then perform trimming and surface inspection. Inspection shows that the wire interlayer gap r = 52μm and the surface roughness Ra = 3.0μm. This meets the requirements of wire interlayer gap r ≤ 60μm and surface roughness Ra ≤ 3.2μm, indicating that the inspection and testing are qualified, and the finished decorative shell for the lower leg prosthesis is obtained. Figure 4 As shown.

[0047] Example 2

[0048] The difference between this embodiment and Embodiment 1 is that the printing parameters are different, as detailed below.

[0049] S1. Scanning and Modeling: A medical 3D scanner is used to scan and model the lower leg prosthesis, obtaining a 3D image data model of the lower leg prosthesis, including the lower leg socket, connectors, metal connecting tubes, prosthetic footplate, and the assembled prosthetic foot skin; then, the lower leg of the healthy side of the patient is scanned and modeled to obtain a 3D image data model of the healthy lower leg, which is used to help establish the outline of the decorative shell of the lower leg prosthesis;

[0050] S2. Model Conversion: Prosthetic technicians use UG 3D software to perform data model fitting and simulation line analysis on the image model of the lower leg prosthesis and the data model of the healthy lower leg. Based on the fitted data model and biomechanics, a 3D printing data model of the decorative shell of the lower leg prosthesis is established.

[0051] S3. Printing: Import the additive manufacturing slicing software, set the additive manufacturing printing parameters, including printing speed of 35mm / s, printing temperature of 215℃, printing thickness of 2.7mm, layer height of 0.4mm, and send it to the additive manufacturing equipment for 3D printing to obtain a one-piece molded lower leg prosthesis decorative shell semi-finished product.

[0052] S4. Post-processing: After printing is completed, allow the semi-finished product to cool naturally, and then perform cutting and surface inspection. After inspection, the wire interlayer gap r = 55μm and the surface roughness Ra = 3.0μm, which meets the requirements of wire interlayer gap r ≤ 60μm and surface roughness Ra ≤ 3.2μm. Therefore, the inspection and testing are qualified, and the finished product of the lower leg prosthesis decorative shell is obtained.

[0053] Example 3

[0054] The difference between this embodiment and Embodiment 1 is that the printing parameters are different, as detailed below.

[0055] S1. Scanning and Modeling: A medical 3D scanner is used to scan and model the lower leg prosthesis, obtaining a 3D image data model of the lower leg prosthesis, including the lower leg socket, connectors, metal connecting tubes, prosthetic footplate, and the assembled prosthetic foot skin; then, the lower leg of the healthy side of the patient is scanned and modeled to obtain a 3D image data model of the healthy lower leg, which is used to help establish the outline of the decorative shell of the lower leg prosthesis;

[0056] S2. Model Conversion: Prosthetic technicians use UG 3D software to perform data model fitting and simulation line analysis on the image model of the lower leg prosthesis and the data model of the healthy lower leg. Based on the fitted data model and biomechanics, a 3D printing data model of the decorative shell of the lower leg prosthesis is established.

[0057] S3. Printing: Import the additive manufacturing slicing software, set the additive manufacturing printing parameters, including printing speed of 30mm / s, printing temperature of 215℃, printing thickness of 2.3mm, layer height of 0.3mm, and send it to the additive manufacturing equipment for 3D printing to obtain a one-piece molded lower leg prosthesis decorative shell semi-finished product.

[0058] S4. Post-processing: After printing is completed, allow the semi-finished product to cool naturally, and then perform cutting and surface inspection. After inspection, the wire interlayer gap r = 48μm and the surface roughness Ra = 2.8μm, which meets the requirements of wire interlayer gap r ≤ 60μm and surface roughness Ra ≤ 3.2μm. Therefore, the inspection and testing are qualified, and the finished product of the lower leg prosthesis decorative shell is obtained.

[0059] Comparative Examples 1-20

[0060] The difference between Comparative Examples 1-20 and Example 1 is that the printing speed and printing temperature parameters in step S3 are different, resulting in different printed product effects, as detailed in Table 1.

[0061]

[0062]

[0063] As demonstrated in Example 1 and Comparative Examples 1-20, precise control of printing speed, printing temperature, printing thickness, and layer height improves mechanical strength and durability, ensuring strong interlayer bonding and reducing the likelihood of breakage or damage. In the 3D printing process, precise control of these parameters can prevent poor interlayer bonding caused by excessive speed, while also improving printing efficiency. Excessive printing speed, before the material has fully cooled and solidified and remains in a fluid state, can lead to improper layer stacking, potentially resulting in poor interlayer bonding, material leakage and stringing during rapid nozzle movement, and voids or material gaps within the printed part, affecting the strength and stability of the printed structure. Conversely, excessively slow printing speeds increase printing time, reduce production efficiency, and may lead to overcooling, further affecting interlayer bonding. Therefore, it is necessary to adjust the printing speed appropriately based on the material characteristics and the performance of the printing equipment to ensure strong interlayer bonding while maintaining high printing efficiency.

[0064] Printing temperature directly affects the flowability and adhesion of materials. Appropriate temperature settings can enhance interlayer bonding strength, preventing material buildup and increased surface roughness due to excessively high temperatures, or poor interlayer bonding and delamination due to excessively low temperatures, leading to printing defects. Temperature also significantly impacts the shrinkage and deformation of 3D printing materials. Materials are typically printed layer by layer through the nozzle in a molten state, and then solidify upon cooling to form the desired shape. During cooling, the material undergoes thermal shrinkage. Lower printing temperatures can reduce deformation and melt density of the printed object, but may result in insufficient adhesion and decreased print quality. Proper temperature control can mitigate this shrinkage, improving dimensional accuracy and shape stability of the printed object. Simultaneously, temperature control can reduce internal stress in the printed object, thereby reducing potential cracks and deformation, and improving print quality. Figure 5 As shown. The temperature setting needs to be adjusted according to the specific material's melting point, thermal conductivity, and other physicochemical properties.

[0065] Adjust the printing speed to 30-45 mm / s based on print quality and efficiency requirements. Higher printing speeds require higher extrusion temperatures. Avoid excessively fast printing speeds, as this can prevent the material from melting sufficiently, leading to poor interlayer adhesion, a rough surface, and voids or material gaps within the printed part. Additionally, rapid nozzle movement can cause material leakage and stringing. Slower speeds contribute to a smoother, finer surface, but excessively slow speeds significantly increase printing time and can cause over-cooling, affecting interlayer bonding.

[0066] Adjusting the printing temperature to 215-225℃ ensures the TPU material is fully melted, guaranteeing smooth extrusion from the nozzle and good adhesion to the printed portion. This increases printing speed and interlayer adhesion, contributing to improved surface quality and internal structural stability of the printed parts. However, excessively high temperatures may cause material buildup or overflow, affecting surface smoothness, or even leading to deformation due to overheating.

[0067] Therefore, the coordinated adjustment of printing speed and temperature is extremely important. Faster printing speeds require correspondingly higher printing temperatures to maintain material flow and ensure effective adhesion to the previous layer. Conversely, slower printing speeds require lower temperatures to prevent excessive material cooling. To balance printing speed and resolution, we need to adjust the temperature appropriately and optimize it according to specific printing needs. Adjusting the printing speed and temperature of a 3D printer is key to ensuring print quality and efficiency.

[0068] To eliminate the dimensional differences between printing speed and printing temperature, scale the features to the same range [0,1], facilitate comparison of feature importance, and perform linear regression, the above data needs to be linearly normalized.

[0069] The formula for Min-Max normalization is as follows:

[0070]

[0071] Where x is the original data value; xmin is the minimum value of the data; xmax is the maximum value of the data; and xnorm is the normalized value.

[0072] The normalized data table of printing speed and printing temperature was obtained, and the results were divided into two states according to whether the printing effect was a qualified finished product: State 1: qualified finished product and State 0: unqualified finished product.

[0073]

[0074] Between-group effect test dependent variable: temperature normalization

[0075]

[0076] Before adjustment, R-squared = 0.719; after adjustment, R-squared = 0.649. Parameter estimation dependent variable: temperature normalization.

[0077]

[0078]

[0079] Based on the overall model performance: F-value = 10.236, p-value = 0.033 (<0.05), R0 2 =0.719, the model has considerable explanatory power and is statistically significant overall. This indicates that the independent variable "speed normalization" has a significant effect on "temperature normalization". The 95% confidence interval is [0.068, 0.959], indicating that the coefficient is statistically reliable.

[0080] According to the linear regression formula: Y = β0 + β1X + ∈; where Y is the dependent variable (printing temperature); X is the independent variable (printing speed); β0 is the intercept; β1 is the slope; and ∈ is the error term.

[0081] Therefore, the printing speed (x) is calculated. v ) and printing temperature (x t The linear regression relationship between x and y is: t =0.51x v +0.2.

[0082] When the printing speed (x) v ) and printing temperature (x t ) satisfies x t -0.51x v When -0.2 > 0,

[0083] Model fitting information

[0084]

[0085] The significance p-value = 0.002 < 0.05 indicates that the model improvement after adding the independent variable is statistically significant.

[0086] Parameter estimation

[0087]

[0088] With a p-value of 0.996 (>0.95), we can deduce y. vt1 =415.7*x v -829.4*x t +258.3.

[0089] When the printing speed (x) v ) and printing temperature (x t ) satisfies x t -0.51x v When -0.2 < 0,

[0090] Model fitting information

[0091]

[0092] The significance p-value = 0.002 < 0.05 indicates that the model improvement after adding the independent variable is statistically significant.

[0093] Parameter estimation

[0094]

[0095] It can be concluded that y vt2 = -412.4*x v +822.4*x t -85.31.

[0096] Logistic regression is a statistical model used for classification problems, especially binary classification problems. Its core principle is to map the output of linear regression to probability values ​​(between 0 and 1) using the logistic function (Sigmoid function).

[0097] According to the formula for logistic regression: Where z = y vt e is the base of the natural logarithm (approximately 2.71828).

[0098] After sorting, it was found that

[0099]

[0100] When the probability P is greater than 50%, it can be considered that the printing speed and printing temperature at this time can print qualified products; when the probability P is less than or equal to 50%, it can be considered that the printing speed and printing temperature at this time cannot print qualified products.

[0101] Comparative Examples 21-41

[0102] The difference between Comparative Examples 21-41 and Example 1 is that the printing thickness and layer height parameters in step S3 are different, resulting in different finished product effects, as detailed in Table 2.

[0103]

[0104] As demonstrated in Example 1 and Comparative Examples 21-41, precise control of the printing speed, temperature, thickness, and layer height ensures that the filament remains in a semi-solid state during printing, allowing each layer to rapidly fuse with the previous layer within a reasonable melting time. In 3D printing, adjusting the printing thickness and layer height are key factors in controlling surface quality, crucial for ensuring good material bonding and preventing shrinkage and delamination during cooling.

[0105] By optimizing these parameters, interlayer gaps can be significantly reduced, as shown in Table 2. This not only improves the structural integrity of the printed part but also enhances its overall performance. Molding the entire part in one piece avoids potential breaks or seams that may occur in traditional manufacturing processes, resulting in higher strength and a more robust and durable finished product. Due to the absence of breaks, the one-piece molded part can distribute pressure more evenly when subjected to external forces, thus improving its overall performance. One-piece molding technology allows for more efficient use of materials and reduces waste during manufacturing. By streamlining assembly and installation steps, the manufacturing process is simplified, improving production efficiency.

[0106] Precise control of print thickness and layer height directly affects the structural strength and surface quality of the printed product. Too thin a print thickness results in insufficient mechanical strength, making the product prone to cracking, deformation, and surface dents, affecting both quality and appearance. Conversely, excessive thickness leads to material buildup, affecting surface smoothness and increasing surface roughness. Thinner layer heights improve the surface smoothness of the printed product, while thicker layer heights create stepped textures and a rougher appearance. Therefore, print parameters must be set appropriately based on the specific needs of the patient.

[0107] Before printing, set the print thickness and layer height parameters. Observe and test the printing effect by setting different print thicknesses and layer heights. Other parameter settings include: print speed 40mm / s, print temperature 220℃.

[0108] The printing thickness is 2.2-2.8mm, which ensures its mechanical strength and durability, making it less prone to breakage or damage and providing good surface quality.

[0109] With a print layer height of 0.25-0.45mm, it maintains a relatively fast printing speed while providing better surface smoothness and detail than thicker layer heights.

[0110] Adjust the printing thickness to 2.3-2.7mm. As the printing thickness increases, the layer height should also be adjusted accordingly. Otherwise, printing time will increase significantly, material consumption will increase, and the precision requirements for the printer will be higher, all of which increase the risk of printing failure. Thicker walls can significantly improve the mechanical strength and durability of the finished product, making it less prone to breakage or damage and providing good surface quality. Insufficient wall thickness will result in insufficient mechanical strength, making the finished product prone to cracking or deformation, and causing uneven surfaces or dents, affecting quality and appearance. Excessive wall thickness will cause material buildup, affecting surface smoothness and increasing surface roughness.

[0111] Adjusting the layer height to 0.3-0.4mm ensures successful printing while maintaining a relatively fast printing speed, providing better surface smoothness and detail compared to thicker layer heights. Excessive layer height increases surface roughness, creates a noticeable staggered effect, and results in poor detail, negatively impacting the overall quality and appearance of the model.

[0112] To eliminate the dimensional differences between print thickness and layer height, scale the features to the same range [0,1], facilitate comparison of feature importance, and perform linear regression, the above data needs to be linearly normalized.

[0113] The formula for Min-Max normalization is as follows:

[0114]

[0115] Where x is the original data value; xmin is the minimum value of the data; xmax is the maximum value of the data; and xnorm is the normalized value.

[0116] A normalized data table of printing thickness and layer height is obtained, and the printing effect is divided into two states according to whether the finished product is qualified: State 1: qualified finished product and State 0: unqualified finished product.

[0117]

[0118]

[0119] Between-group effect test

[0120] Dependent variable: thickness normalization

[0121]

[0122] Before adjustment, R² = 0.481; after adjustment, R² = 0.423.

[0123] Parameter estimation

[0124] Dependent variable: thickness normalization

[0125]

[0126] Based on the overall model performance: F-value = 8.345, p-value = 0.018 (<0.05), R0 2 =0.481, the model has considerable explanatory power and is statistically significant overall. This indicates that the independent variable "floor height normalization" has a significant impact on "thickness normalization". The 95% confidence interval is [0.261, 2.145], indicating that the coefficient is statistically reliable.

[0127] According to the linear regression formula: Y = β0 + β1X + ∈; where Y is the dependent variable (print thickness); X is the independent variable (floor height); β0 is the intercept; β1 is the slope; and ∈ is the error term. Therefore, the floor height (x...) h ) and printing thickness (x d The linear regression relationship between x and y is: d =1.2x h +0.07. When the floor height (x h ) and printing thickness (x d ) satisfies x d -1.2x h When -0.07 > 0,

[0128] Model fitting information

[0129]

[0130] The significance p-value = 0.046 < 0.05, indicating that the model improvement after adding the independent variable was statistically significant.

[0131] Parameter estimation

[0132]

[0133] It can be concluded that y hd1 =-10.28*x h -8.61*x d +1.96.

[0134] When the floor height (x) h ) and printing thickness (x d ) satisfies x d -1.2x h When -0.07 < 0,

[0135] Model fitting information

[0136]

[0137] The significance p-value = 0.002 < 0.05 indicates that the model improvement after adding the independent variable is statistically significant.

[0138] Parameter estimation

[0139]

[0140]

[0141] It can be concluded that y hd2 =-131.42*x d +333.54*x h +15.49.

[0142] Using a logistic regression model, the output of linear regression is mapped to probability values ​​(between 0 and 1) through the logistic function (Sigmoid function). According to the logistic regression formula: Where z = y hd e is the base of the natural logarithm (approximately 2.71828).

[0143] After sorting, it was found that

[0144]

[0145] When the probability P is greater than 50%, it can be considered that the layer height and printing thickness at this time can print qualified products; when the probability P is less than or equal to 50%, it can be considered that the layer height and printing thickness at this time cannot print qualified products.

[0146] Those skilled in the art will readily understand that the above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A manufacturing process for an additively manufactured one-piece prosthetic decorative shell, characterized in that, It includes the following steps: S1. Scanning and modeling: Use a medical 3D scanner to scan and model a healthy calf to obtain a 3D image data model; S2. Model conversion: Use 3D software to perform data model fitting and simulation alignment analysis on the 3D image data model, and convert it into a 3D printing data model of the cosmetic shell of the calf prosthesis; S3. Printing: Import the 3D printing data model into additive manufacturing slicing software, set the printing parameters of additive manufacturing, and send it to the additive manufacturing equipment for 3D printing to obtain a semi-finished product of the integrally formed cosmetic shell of the calf prosthesis; S4. Post-processing: Cut the semi-finished product of the cosmetic shell of the calf prosthesis, and perform surface inspection and elasticity test. After passing the inspection and test, the finished product of the cosmetic shell of the calf prosthesis can be obtained; The printing parameters in step S3 include printing speed, printing temperature, printing thickness, and layer height. By controlling the printing speed, printing temperature, printing thickness, and layer height of the material, each newly printed layer of material can be quickly integrated with the already printed layer within the melting time; After normalizing the printing parameters in step S3, a normalized printing speed value is obtained. Printing temperature normalization value Print thickness normalization value and floor height normalization value , ， ， e is the base of the natural logarithm, when and A product can be obtained if the ratio is greater than 50%.

2. The manufacturing process of the prosthetic decorative shell according to claim 1, characterized in that, The surface inspection in step S4 is specifically that the wire gap r ≤ 60 μm and the surface roughness Ra ≤ 3.2 μm are considered qualified for inspection.

3. The manufacturing process of the prosthetic decorative shell according to claim 1, characterized in that, The elasticity test in step S4 is specifically that the pressure of the semi-finished product P1 of the cosmetic shell of the calf prosthesis measured by the plastic tensile property test method is between 26.2 - 31.8 MPa, which is considered qualified for testing.

4. The manufacturing process of the prosthetic decorative shell according to claim 1, characterized in that, The medical 3D scanner in step S1 is any one of a composite 3D scanner, a 3D laser scanner, and an intelligent blue light handheld 3D scanner.

5. The manufacturing process of the prosthetic decorative shell according to claim 3, characterized in that, The 3D software in step S2 is any one of UG, Solidworks, CAD, and Creo; the additive manufacturing slicing software in step S3 is any one of KISSlicer, ideaMaker, OctoPrint, and 3DPrinterOS.

6. The manufacturing process of the prosthetic decorative shell according to claim 5, characterized in that, The additive manufacturing equipment in step S3 is any one of SLA, SLM, SLS, FGF, and FDM.

7. The manufacturing process of the prosthetic decorative shell according to claim 6, characterized in that, The semi-finished product of the cosmetic shell of the calf prosthesis in step S3 is made of thermoplastic polyurethane rubber material.

8. The prosthetic decorative shell manufactured according to any one of claims 1-7, characterized in that, It includes an upper cavity and a lower cavity. A receiving cavity connecting device is provided at the top of the upper cavity, a first nested ring is provided at the bottom of the upper cavity, a second nested ring is provided at the top of the lower cavity, the first nested ring and the second nested ring are detachably and fixedly connected, and a footplate shell connecting device is provided at the bottom of the lower cavity.

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