An additive manufacturing method for zirconium-niobium alloy orthopedic implants

Abstract

The present invention relates to an additive manufacturing method for zirconium-niobium alloy orthopedic implants, including: model design: adding an auxiliary sheet in the jump printing area of ​​the zirconium-niobium alloy part, the auxiliary sheet and the edge of the zirconium-niobium alloy part have a preset distance; melting path planning; when the melting path planning is performed on the jump printing area, the auxiliary sheet is set as the starting position or the ending position of the high-energy beam scanning; printing preparation; melting process design; repeated melting; part post-processing. The present invention sets an auxiliary sheet in the jump printing area, so that when the high-energy beam scans through the jump printing area, the high-energy beam is turned on from the auxiliary sheet. The high-energy beam will first scan the auxiliary sheet in the initial stage of starting, and then the part will be printed when the energy of the high-energy beam reaches the standard value, so that the energy required for the melting scanning of the part can be guaranteed, and the hole defects caused by the energy attenuation of the scanning line when the beam is closed or opened can be avoided.

Description

Technical Field

[0001] The embodiments of the present invention relate to the field of additive manufacturing technology, and in particular to an additive manufacturing method for zirconium-niobium alloy orthopedic implants. Background Art

[0002] Zirconium-niobium (ZrNb) alloys have become a new generation of orthopedic implants with excellent biocompatibility, low elastic modulus and low magnetic susceptibility, and can partially replace titanium alloys in the manufacture of orthopedic implants. On the one hand, low elastic modulus zirconium-niobium alloys help reduce stress shielding caused by biomechanical incompatibility between implants and human bones. On the other hand, when patients with orthopedic implants undergo MRI examinations, zirconium-niobium alloys also have lower magnetic susceptibility, which can reduce MRI artifacts. In addition, zirconium-niobium alloys also have high strength, good toughness and biocompatibility, making them the main materials for medical devices and implants.

[0003] The current use of advanced additive manufacturing technology helps to better achieve efficient forming of ZrNb alloy implants. Additive manufacturing technology uses high-energy beams as energy sources, scans metal powders at high speed under vacuum protection, and manufactures three-dimensional complex structures by melting and superimposing layer by layer.

[0004] When manufacturing complex orthopedic implants made of zirconium-niobium alloy by additive manufacturing, holes are prone to occur at the edges of formed parts, which affects the forming quality of orthopedic implant parts. Through analysis, it can be seen that there are two reasons for the holes at the edges: first, the melting energy at the edge of the part is insufficient. By looking at the scanning lines of the path planning of the printing model of the zirconium-niobium alloy orthopedic implant part, it can be seen that due to unreasonable path planning, the spacing between the melting lines in the local area becomes wider (the melting line spacing d in the melting energy density formula becomes larger, and the melting energy density E becomes smaller), resulting in the melting of the edge of the part. The energy density of the melt body decreases, causing under-melting and melting depression problems at the edge of the part. Second, due to the melting and solidification of the edge of the zirconium-niobium alloy part, a tiny concave area will be generated. When the powder is laid, this tiny concave area will accumulate more powder than other areas (the actual powder thickness t in the melting energy density formula becomes larger, and the melting energy density E becomes smaller). The increase in the amount of powder indirectly causes the melt energy density in this area to decrease again, causing hole defects when the edge of the part is melted.

[0005] Melting energy density formula:

[0006]

[0007] U is the melting voltage, I is the melting current, v is the melting speed, t is the actual powder thickness, and d is the melting line spacing.

[0008] The melting point of refractory metal zirconium and zirconium alloys is above 1800°C. The size, shape, depth and dynamic changes of the molten pool formed by the electron beam melting heat source directly affect the melting quality of the parts. In addition, the complex thermal field of the melting section of complex zirconium-niobium alloy orthopedic implants makes it difficult to ensure the quality uniformity of zirconium-niobium alloy orthopedic implants manufactured by powder bed additive manufacturing.

[0009] Therefore, it is necessary to improve one or more problems existing in the above-mentioned related technical solutions.

[0010] It should be noted that this section is intended to provide background or context for the technical solutions of the present invention stated in the claims. The description herein is not admitted to be prior art by inclusion in this section. Summary of the invention

[0011] The object of the present invention is to provide a method for additive manufacturing of zirconium-niobium alloy orthopedic implants, thereby solving one or more problems caused by limitations and defects of the related art at least to a certain extent.

[0012] The present invention provides an additive manufacturing method for a zirconium-niobium alloy orthopedic implant, comprising:

[0013] Model design: using modeling software to establish an initial printing model of the zirconium-niobium alloy part of the orthopedic implant, based on the initial printing model, adding an auxiliary sheet in the jump printing area of ​​the zirconium-niobium alloy part, wherein the auxiliary sheet has a preset distance from the edge of the zirconium-niobium alloy part, and exporting the printing model of the zirconium-niobium alloy part including the auxiliary sheet;

[0014] Melting path planning: using model slicing software to perform layer-by-layer slicing and melting path planning along the height direction of the zirconium-niobium alloy part printing model; when performing melting path planning for the jump printing area, setting the auxiliary sheet as the starting position or the ending position of the high-energy beam scanning;

[0015] Printing preparation: Load zirconium-niobium alloy powder into the additive manufacturing equipment, level the forming substrate, lower the forming substrate, evacuate the additive manufacturing equipment, load the high-energy beam, preheat the forming substrate, spread the powder, and heat the powder bed;

[0016] Melting process design: Use high-energy beam to melt scan the zirconium-niobium alloy powder according to the melting path;

[0017] Repeated melting: Repeat the powder laying, powder bed heating and melting scanning process to form printed parts;

[0018] Part post-processing: Take the zirconium-niobium alloy parts out of the additive manufacturing equipment and perform part post-processing.

[0019] In the present invention, according to the melting path of the jump printing area, the length of the auxiliary sheet along the jump direction of the scanning line is 1-5 mm.

[0020] In the present invention, the preset distance between the auxiliary sheet and the edge of the zirconium-niobium alloy part is 1-3 mm.

[0021] In the present invention, the step of melting path planning also includes:

[0022] In the edge area of ​​the zirconium-niobium alloy part close to the jump printing area, melting lines are added to the area where the melting line spacing is greater than a preset value.

[0023] In the present invention, the step of designing the melting process further includes: performing compensatory melting on the edge area.

[0024] In the present invention, the preset value of the melting line spacing is 0.05-0.15 mm.

[0025] In the present invention, in the step of adding melting lines to an area where the melting line spacing is greater than a preset value in the edge area of ​​the zirconium-niobium alloy part close to the jump printing area, a melting line is added in the middle position of the area where the melting line spacing is greater than the preset value.

[0026] In the present invention, the step of compensating the melting of the edge region comprises:

[0027] The edge region is subjected to a melting scan using a melting energy density that is lower than that of the non-edge region.

[0028] In the present invention, the melting energy density of the edge region is 1 / 4 to 1 / 2 of the melting energy density of the non-edge region.

[0029] In the present invention, the melting current of the non-edge area is 10~20mA, and the melting speed is 4~6m / s; the melting current of the newly added melting line in the edge area is 1 / 4~1 / 2 of the melting current of the non-edge area, and the melting speed of the edge area is the same as the melting speed of the non-edge area.

[0030] The technical solution provided by the present invention may include the following beneficial effects:

[0031] In the present invention, an auxiliary sheet is arranged in the jump printing area, so that when the high-energy beam scans through the jump printing area, the high-energy beam is turned on from the auxiliary sheet. The high-energy beam will first scan the auxiliary sheet in the initial stage of startup, and then when the energy of the high-energy beam reaches the standard value, the parts will be printed. In this way, the energy required for the melting scan of the parts can be guaranteed, and hole defects caused by energy attenuation when the scanning line is closed or opened can be avoided. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] The accompanying drawings herein are incorporated into the specification and constitute a part of the specification, illustrate embodiments consistent with the present disclosure, and together with the specification are used to explain the principles of the present disclosure. Obviously, the accompanying drawings described below are only some embodiments of the present disclosure, and for ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without creative work.

[0033] Figure 1 A schematic flow chart showing a method for additive manufacturing of a zirconium-niobium alloy orthopedic implant in an exemplary embodiment of the present invention;

[0034] Figure 2 A schematic diagram showing the position structure of the auxiliary sheet in an exemplary embodiment of the present invention;

[0035] Figure 3 A schematic diagram showing a structure in which a melting line is added to an edge region in an exemplary embodiment of the present invention;

[0036] Figure 4 A schematic diagram showing a high energy beam jump process in an exemplary embodiment of the present invention is shown;

[0037] Figure 5 Comparative photographs of zirconium-niobium alloy parts of the comparative example and the test example are shown. DETAILED DESCRIPTION

[0038] Example embodiments will now be described more fully with reference to the accompanying drawings. However, example embodiments can be implemented in many forms and should not be construed as limited to the examples set forth herein; rather, these embodiments are provided so that the present invention will be more comprehensive and complete and fully convey the concepts of the example embodiments to those skilled in the art. The described features, structures, or characteristics may be combined in any suitable manner in one or more embodiments.

[0039] In addition, the accompanying drawings are only schematic illustrations of embodiments of the present invention and are not necessarily drawn to scale. The same reference numerals in the drawings represent the same or similar parts, and their repeated descriptions will be omitted. Some of the block diagrams shown in the accompanying drawings are functional entities and do not necessarily correspond to physically or logically independent entities.

[0040] In this example embodiment, a method for additive manufacturing of a zirconium-niobium alloy orthopedic implant is first provided. Figure 1 As shown, the additive manufacturing method includes the following steps:

[0041] Step S101, model design: using modeling software to establish an initial printing model of the zirconium-niobium alloy part of an orthopedic implant, based on the initial printing model, adding an auxiliary sheet 100 in the jump printing area of ​​the zirconium-niobium alloy part, the auxiliary sheet 100 having a preset distance from the edge of the zirconium-niobium alloy part, and deriving a printing model of the zirconium-niobium alloy part including the auxiliary sheet 100. The auxiliary sheet 100 can be set at all places near the edge of the printed part in the jump printing area, for example, Figure 2 In the embodiment, an auxiliary sheet 100 may be provided at any of the left and right locations of the U-shaped inner side of the printed part near the edge of the part, such as Figure 2 As shown, the auxiliary sheet 100 is arranged at the left of the U-shaped inner side of the printed part. Of course, an auxiliary sheet 100 can also be arranged at the left and right places of the U-shaped inner side of the printed part near the edge of the part.

[0042] Step S102, melting path planning: using model slicing software to perform layer-by-layer slicing and melting path planning along the height direction of the zirconium-niobium alloy part printing model; when performing melting path planning for the jump printing area, the auxiliary sheet 100 is set as the starting position or the ending position of the high-energy beam scanning.

[0043] Step S103, printing preparation: loading zirconium-niobium alloy powder into the additive manufacturing equipment, leveling the forming substrate, lowering the forming substrate, evacuating the additive manufacturing equipment, loading the high-energy beam, preheating the forming substrate, spreading the powder, and heating the powder bed.

[0044] Step S104, melting process design: using a high energy beam to perform melting scanning on the zirconium-niobium alloy powder according to the melting path.

[0045] Step S105, repeated melting: repeating the powder spreading, powder bed heating and melting scanning processes to form a printed part.

[0046] Step S106, part post-processing: taking out the zirconium-niobium alloy part from the additive manufacturing equipment and performing part post-processing.

[0047] First, the meaning of the jump printing area is explained. The jump printing area refers to the discontinuous area where the part exists. For example, if the cross section of the part is U-shaped, in the upper half of the U-shaped cross section, during the printing process from the left side to the right side or from the right side to the left side, the empty area in the middle (jump printing area) is not printed, that is, the scanning will cause a jump, and the energy beam needs to be closed and opened before and after the jump. In the related art, for example, when scanning from the right side to the left side of the U-shaped, the high-energy beam will be turned off when the cross section of the right part is scanned (that is, when it reaches the jump printing area), and when it reaches the left side of the U-shaped (that is, when it leaves the jump printing area), the high-energy beam will be turned on to continue scanning the left side. In the process of closing and opening the high-energy beam, especially when the high-energy beam is turned on, it takes a certain amount of time for its energy to reach the energy value during operation, which will cause insufficient energy when the high-energy beam is turned on, and then the powder will be under-melted during printing, resulting in hole defects in the parts.

[0048] In this embodiment, an auxiliary sheet 100 is set in the jump printing area, so that when the high-energy beam scans through the jump printing area, the high-energy beam is turned on from the auxiliary sheet 100. The high-energy beam will first scan the auxiliary sheet 100 in the initial stage of startup, and then when the energy of the high-energy beam reaches the standard value, the parts will be printed. In this way, the energy required for the melting scan of the parts can be guaranteed, and hole defects caused by energy attenuation when the scanning line is closed or opened can be avoided.

[0049] It should be noted that, based on the above embodiments, please refer to Figure 2 The length of the auxiliary sheet 100 in the scanning line jump direction is f=1~5mm, for example, it can be 2mm, 3mm, 4mm, etc.; the preset distance between the auxiliary sheet 100 and the edge of the zirconium-niobium alloy part, for example, can be e=1~3mm in the horizontal direction, for example, it can be 2mm, etc., and can be g=1~3mm in the longitudinal direction, and the values ​​in the horizontal direction and the vertical direction can be different.

[0050] In addition, in order to further improve the under-melting situation when printing parts, when planning the melting path, in the edge area of ​​the zirconium-niobium alloy part close to the jump printing area, a melting line is added to the area where the melting line spacing is greater than the preset value. It should be noted that in the printing process of the prior art, usually no melting line is set in the area where the width of the edge area is greater than one times the melting line spacing and less than two times the melting line spacing. Because in the prior art, the inherent scanning line division method is an equal-interval division method, and the division area is from the nearest end to the farthest end of the part. When the middle edge area of ​​the part is encountered during the average division process, if the distance is not enough for twice the set spacing value, it will automatically jump to the next edge line to continue the division, so the melting line will not be automatically divided here. Please refer to Figure 3 This application breaks the existing technology by adding a melting line (cn 、a n Both places are newly added melting lines), so that the melting of the edge area is compensated. In some embodiments, the preset value of the melting line spacing can be 0.05~0.15mm, such as 0.10mm, 0.12mm, etc., but it is not limited to this. In addition, Figure 3 In the figure, c1 and a1 are the outer contours of the part, and a melt line can also be added in the edge area of ​​the contour. Rectangle 1' is an enlarged view of rectangle 1, and rectangle 2' is an enlarged view of rectangle 2.

[0051] Furthermore, the scanning parameters of the melting line added to the edge area are different from those of other non-edge areas. The melting energy density used in the edge area of ​​the present application is relatively low, which is 1 / 4 to 1 / 2 of the melting energy density of other non-edge areas.

[0052] When the melting current of the non-edge area is 10~20mA and the melting speed is 4~6m / s, the melting current of the newly added melting line in the edge area is 1 / 4~1 / 2 of the melting current of the non-edge area, and the melting speed of the edge area is the same as that of the non-edge area. Melting compensation of the edge area according to the set melting energy density can further improve the under-melting situation during part printing, ensure sufficient melting of the edge area, eliminate the hole defects in the edge area, and improve the yield rate of mass production of products.

[0053] Please refer to Figure 4 , the high-energy beam jumps from the right to the left of the part for printing. After the auxiliary sheet 100 is set, the high-energy beam is turned on at the auxiliary sheet 100. After reaching the edge of the part near the auxiliary sheet 100, the energy has reached the printing requirement and will fully melt the laid powder, so that the powder layer thickness changes from a smaller t0 value to a larger t1 value; by adding a melting line to the edge area (i.e. Figure 4 c n The new melting line at the edge of the part can make the edge melt more fully and reduce the possibility of holes.

[0054] A specific test example is listed below to further illustrate the method and technical effects of the present application.

[0055] like Figure 5 As shown, the picture on the left is a zirconium-niobium alloy knee joint prosthesis of a comparative example, and the picture on the right is a zirconium-niobium alloy knee joint prosthesis of a test example.

[0056] When printing the zirconium-niobium alloy knee prosthesis in the comparative example, pores appeared at the edge of the sample. Figure 5 As shown in the figure on the left.

[0057] The process of implementing the test example of this application is as follows:

[0058] Model design, using modeling software to establish the initial printing model of the zirconium-niobium alloy parts, placing the zirconium-niobium alloy parts, adding auxiliary sheets 100 in the jump printing area of ​​the zirconium-niobium alloy parts, such as Figure 5 As shown in the right picture, there is a 2 mm gap between the auxiliary sheet 100 and the edge of the zirconium-niobium alloy part, the thickness of the auxiliary sheet 100 in the scanning direction is 2 mm, and a printing model of the zirconium-niobium alloy part including the auxiliary sheet 100 is exported.

[0059] Melting path planning: Use the model slicing software to perform layer-by-layer slicing and melting path planning along the height direction of the zirconium-niobium alloy part printing model; when planning the melting path for the jump printing area, set the auxiliary sheet 100 to the starting position or the ending position of the high-energy beam scanning. In the edge area of ​​the zirconium-niobium alloy part close to the jump printing area, a melting line is added in the area where the melting line spacing is greater than the preset value. Compensation melting is performed on the edge area of ​​the melting line. The preset value of the melting line spacing is 0.1mm. In the edge area of ​​the zirconium-niobium alloy part close to the jump printing area, a melting line is added in the area where the melting line spacing is greater than the preset value.

[0060] Melting process design: The melting current of the non-edge area is 16.2mA, the melting speed is 4.6m / s, the melting current of the newly added melting line is 8mA, and the scanning speed is 4.6m / s.

[0061] After the auxiliary sheet 100 and the newly added melting line are provided, the edge area next to the porous structure of the prepared zirconium-niobium alloy part ( Figure 5 There are no holes in the rectangular frame line in the figure, and the forming quality is good.

[0062] It should be noted that Figure 5 The porous structure at the edge of the part is a designed structure of the part and is not a defect of the part.

[0063] It should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like that may appear in the above description indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the embodiments of the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the embodiments of the present invention.

[0064] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of the embodiments of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0065] In the embodiments of the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, or a detachable connection or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0066] In the embodiments of the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may include that the first and second features are in direct contact, or may include that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, a first feature being "above", "above" and "above" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. A first feature being "below", "below" and "below" a second feature includes that the first feature is directly below and obliquely below the second feature, or simply indicates that the first feature is lower in level than the second feature.

[0067] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example" or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification.

[0068] Those skilled in the art will readily appreciate other embodiments of the present invention after considering the specification and practicing the invention disclosed herein. This application is intended to cover any variations, uses or adaptations of the present invention, which follow the general principles of the present invention and include common knowledge or customary techniques in the art that are not disclosed by the present invention. The specification and examples are intended to be exemplary only, and the true scope and spirit of the present invention are indicated by the appended claims.

Claims

1. An additive manufacturing method for zirconium-niobium alloy orthopedic implants, characterized in that: include: Model design: using modeling software to establish an initial printing model of the zirconium-niobium alloy part of the orthopedic implant, based on the initial printing model, adding an auxiliary sheet in the jump printing area of ​​the zirconium-niobium alloy part, wherein the auxiliary sheet has a preset distance from the edge of the zirconium-niobium alloy part, and exporting the printing model of the zirconium-niobium alloy part including the auxiliary sheet; Melting path planning: using model slicing software to perform layer-by-layer slicing and melting path planning along the height direction of the zirconium-niobium alloy part printing model; when performing melting path planning for the jump printing area, setting the auxiliary sheet as the starting position or the ending position of the high-energy beam scanning; in the edge area of ​​the zirconium-niobium alloy part close to the jump printing area, adding melting lines to the area where the melting line spacing is greater than a preset value; Printing preparation: Load zirconium-niobium alloy powder into the additive manufacturing equipment, level the forming substrate, lower the forming substrate, evacuate the additive manufacturing equipment, load the high-energy beam, preheat the forming substrate, spread the powder, and heat the powder bed; Melting process design: Use high-energy beam to melt scan the zirconium-niobium alloy powder according to the melting path; Repeated melting: Repeat the powder laying, powder bed heating and melting scanning process to form printed parts; Part post-processing: Take the zirconium-niobium alloy parts out of the additive manufacturing equipment and perform part post-processing.

2. The additive manufacturing method of zirconium-niobium alloy orthopedic implant according to claim 1, characterized in that: According to the melting path of the jump printing area, the length of the auxiliary sheet along the jump direction of the scanning line is 1-5 mm.

3. The additive manufacturing method of zirconium-niobium alloy orthopedic implant according to claim 1, characterized in that: The preset distance between the auxiliary sheet and the edge of the zirconium-niobium alloy part is 1-3 mm.

4. The additive manufacturing method of zirconium-niobium alloy orthopedic implant according to claim 1, characterized in that: The step of designing the melting process also includes: performing compensatory melting on the edge area.

5. The additive manufacturing method of zirconium-niobium alloy orthopedic implant according to claim 4, characterized in that: The preset value of the melting line spacing is 0.05-0.15 mm.

6. The additive manufacturing method of zirconium-niobium alloy orthopedic implant according to claim 4, characterized in that: In the step of adding melting lines to an area where the melting line spacing is greater than a preset value in the edge area of ​​the zirconium-niobium alloy part close to the jump printing area, a melting line is added at a middle position of the area where the melting line spacing is greater than the preset value.

7. The additive manufacturing method of zirconium-niobium alloy orthopedic implant according to claim 4, characterized in that: The step of compensating the melting of the edge region comprises: The edge region is subjected to a melting scan using a melting energy density that is lower than that of the non-edge region.

8. The additive manufacturing method of zirconium-niobium alloy orthopedic implant according to claim 7, characterized in that: The melting energy density of the edge region is 1 / 4 to 1 / 2 of the melting energy density of the non-edge region.

9. The additive manufacturing method of zirconium-niobium alloy orthopedic implant according to claim 8, characterized in that: The melting current of the non-edge area is 10~20mA, and the melting speed is 4~6m / s; the melting current of the newly added melting line in the edge area is 1 / 4~1 / 2 of the melting current of the non-edge area, and the melting speed of the edge area is the same as that of the non-edge area.

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