Large format overhanging area unsupported powder bed additive manufacturing method

Abstract

The present application relates to the technical field of additive manufacturing, and discloses a large-format overhanging area support-free powder bed additive manufacturing forming method, which divides the overhanging area into a bonding forming area and a melting solidification area, realizes the structural self-supporting of the overhanging area processing, avoids the cumbersome steps of using additional support structures in the traditional method, and effectively solves the pain point problem of the difficulty in removing the support structure in the traditional additive manufacturing. In addition, a binder forming allowance compensation area is designed at the bottom of the bonding forming area, the vertical height of the binder forming allowance compensation area is set to not only ensure the difference between the loose bulk density of the metal powder and the corresponding metal material density, avoid the size deviation generated in the subsequent sintering process after the printing of the to-be-processed part is completed, but also ensure the stability and support strength of the bonding forming area, and further improve the precision and overhanging surface quality of the overhanging area under the condition of no external support.

Description

Technical Field

[0001] This invention relates to the field of additive manufacturing technology and discloses a method for additive manufacturing of large-format overhanging areas using unsupported powder bed additive manufacturing. Background Technology

[0002] Laser powder bed fusion (L-PBF) is an advanced additive manufacturing technology. Due to its high forming precision, excellent comprehensive mechanical properties, and ability to form complex parts, it is widely used in the aerospace industry for integrated lightweight components and in the mold industry for complex components. The principle of L-PBF forming is as follows: a designed 3D model is cut into thin sheets of a certain thickness, and then the energy of a laser beam is used to melt powder into the shape of these sheets. These sheets are then stacked layer by layer to form the component. Theoretically, L-PBF technology can form arbitrarily complex parts. However, in actual printing, due to the thermoforming characteristics of L-PBF, support structures are often required to assist in heat dissipation and prevent warping of the formed part caused by thermal stress, especially in the forming of low-angle samples. The currently accepted optimal forming angle for L-PBF is 45°. When the forming angle is less than 45°, support structures are needed to assist in forming. While adding support structures can effectively assist in part forming, it often comes with drawbacks such as increased printing time and material consumption, increased post-processing difficulty, and increased roughness of the support surface. Moreover, for some parts with internal hollows or complex flow channels, the internal support cannot be removed, so L-PBF technology cannot be used for forming.

[0003] Some known technologies employ supportless printing methods, such as adjusting laser energy density and forming scanning strategies. By increasing the scanning speed and thus reducing laser energy input, the forming quality of the overhanging surface can be effectively improved. Alternatively, by adjusting the forming scanning strategy of the overhanging sample, the temperature gradient during the forming process can be effectively reduced, forming stress can be decreased, and the forming stability of the overhanging sample can be improved. However, when the tilt angle of the overhanging surface relative to the printing plane is less than 25°, or when the overhanging area is large, this method is difficult to obtain an overhanging surface with sufficiently high surface quality. Summary of the Invention

[0004] The purpose of this invention is to provide a method for unsupported powder bed additive manufacturing of large-format overhanging areas, which avoids the problem of needing to use additional support structures, and further improves the accuracy and overhanging surface quality of the overhanging area under the condition of no external support while ensuring the stability and support strength of the bonding forming area.

[0005] To achieve the above-mentioned technical effects, the technical solution adopted by the present invention is as follows:

[0006] A large-format, unsupported powder bed additive manufacturing method for overhanging areas includes:

[0007] Based on the arrangement and position of the model of the part to be processed on the powder bed of the additive manufacturing equipment, the overhang area and solid support area of ​​the additive manufacturing part are identified. The overhang area is the part structure area with an overhang angle of 0 to 20° and a maximum length of the overhang structure projected onto the surface of the powder bed ≥ 30 mm. The solid support area is other solid structure areas besides the overhang area.

[0008] The overhanging area is divided from bottom to top into a bonding and forming zone and a melting and solidification zone along the vertical height direction of the part model to be processed in the powder bed;

[0009] A binder forming allowance compensation area is designed on the lower surface of the bonding forming area. The vertical height of the binder forming allowance compensation area is obtained by analyzing h=D(1-ρ1 / ρ), where h is the vertical height of the binder forming allowance compensation area, D is the vertical height of the bonding forming area, ρ1 is the loose density of the metal powder, and ρ is the density of the metal material corresponding to the metal powder.

[0010] Based on the positional relationship between the solid support area, the overhang area, and the adhesive forming allowance compensation area, powder is laid layer by layer from bottom to top. A fusion mechanism is used to melt and solidify the metal powder at the layup processing positions corresponding to the solid support area and the melt solidification area in situ. An adhesive spraying mechanism is used to bond and solidify the metal powder at the layup processing positions corresponding to the bonding forming area and the adhesive forming allowance compensation area, until all solid support areas and overhang areas of the additive manufacturing part to be processed are completed.

[0011] Furthermore, the fusion mechanism is a laser melting device.

[0012] Furthermore, the vertical height of the bonding forming zone is greater than or equal to four times the thickness of a single forming layer in the solid support zone of the part to be processed during the additive manufacturing process.

[0013] Furthermore, the method of in-situ melting and solidifying the metal powder at the layup processing position of the solid support region using a fusion mechanism includes: laying powder layer by layer on a powder bed, scanning the metal powder at each layup processing position layer by layer with a laser of the designed line energy of the solid support region, and completing the processing of the solid support region.

[0014] Furthermore, the bonding forming area or adhesive forming allowance compensation area at the same vertical height position is formed preferentially.

[0015] Furthermore, during the processing of the solid support area, at the position where the solid support area is in lateral contact with the bonding forming area and the adhesive forming allowance compensation area, the forming layer of each solid support area is offset by a light spot distance towards the corresponding bonding forming area or adhesive forming allowance compensation area.

[0016] Furthermore, the processing method for the melt-solidified zone of the overhanging region includes:

[0017] After the bonding forming zone is cured, the powder bed is lowered by a first layer thickness value, powder is spread, and the metal powder at the current layup processing position is scanned by a laser with 40% of the design line energy of the solid support zone, and sintered to form a first sintered thin layer, which is located on the top layer of the bonding forming zone.

[0018] The powder bed is lowered by a first layer thickness value, powder is spread, and the metal powder at the current layup position is scanned by a laser with 60% of the line energy of the solid support area design, and sintered to form a second sintered thin layer, which is located on top of the first sintered thin layer.

[0019] The powder bed is lowered by a first layer thickness value, powder is spread, and the metal powder at the current layup processing position is scanned by a laser with 80% of the design line energy of the solid support area, and sintered to form a third sintered thin layer, which is located on top of the second sintered thin layer;

[0020] Powder is laid layer by layer above the third sintered thin layer. The metal powder at the current layup position is scanned layer by layer by a laser with the line energy of the solid support area. The molten solidification area is connected with the adjacent solid support area to form a single-layer cross-section of the part to be processed, until the processing of the remaining overhang area is completed.

[0021] Furthermore, during the scanning and processing of the solid support area and the melt-solidified area, the interlayer rotation angle between two adjacent forming layers is 67°.

[0022] Furthermore, the thickness of a single forming layer in the solid support area of ​​the additive manufacturing part ranges from 20 to 60 μm during the additive manufacturing process.

[0023] Furthermore, the thickness of a single forming layer during the processing of the bonding forming zone and the adhesive forming allowance compensation zone is 40-120 μm.

[0024] Compared with the prior art, the beneficial effects of this invention are:

[0025] 1. This invention divides the overhanging area into a bonding forming area and a melting and solidification area, thereby achieving structural self-support in the processing of the overhanging area. This avoids the cumbersome steps required by traditional methods that require additional support structures, thus effectively solving the problem of difficult removal of support structures in traditional additive manufacturing.

[0026] 2. This invention designs an adhesive forming allowance compensation zone at the bottom of the bonding forming zone. The vertical height of this adhesive forming allowance compensation zone not only ensures the difference between the loose density of the metal powder and the density of the corresponding metal material, avoiding dimensional deviations that occur during the subsequent sintering process after the part to be processed is printed, but also further improves the accuracy of the overhang area and the quality of the overhang surface under the condition of no external support while ensuring the stability and support strength of the bonding forming zone. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the structure of the part to be processed in Example 1 or 2;

[0028] Figure 2 This is a schematic diagram showing the division of the hanging area and solid support area of ​​the part to be processed in Example 1 or 2.

[0029] Figure 3 This is a schematic diagram of laser melting and forming of the overhanging area in Example 1 or 2;

[0030] Among them, 1. Powder bed; 2. Overhanging area; 201. Adhesive forming area; 202. Melting and solidification area; 3. Solid support area; 4. Adhesive forming allowance compensation area; 5. Fusion mechanism; 6. Adhesive spraying mechanism; 7. Scraper. Detailed Implementation

[0031] The present invention will now be described in further detail with reference to the embodiments and accompanying drawings. However, this should not be construed as limiting the scope of the above-described subject matter of the present invention to the following embodiments; all technologies implemented based on the content of the present invention fall within the scope of the present invention.

[0032] Example 1

[0033] See Figures 1-3 A method for unsupported powder bed additive manufacturing of large-format overhanging areas, including:

[0034] Based on the arrangement and position of the model of the part to be processed on the powder bed 1 of the additive manufacturing equipment, the overhang area 2 and the solid support area 3 of the additive manufacturing part are identified. The overhang area 2 is a part structure area with an overhang angle of 0 to 20° and a maximum length of the overhang structure projected onto the upper surface of the powder bed 1 of ≥30mm. The solid support area 3 is other solid structure areas besides the overhang area 2.

[0035] Along the vertical height direction of the part model to be processed in the powder bed 1, the overhanging area 2 is divided from bottom to top into a bonding and forming area 201 and a melting and solidification area 202;

[0036] A binder forming allowance compensation area 4 is designed on the lower surface of the bonding forming area 201. The vertical height of the binder forming allowance compensation area 4 is obtained by analysis based on h=D(1-ρ1 / ρ), where h is the vertical height of the binder forming allowance compensation area 4, D is the vertical height of the bonding forming area 201, ρ1 is the loose density of the metal powder, and ρ is the density of the metal material corresponding to the metal powder.

[0037] Based on the positional relationship between the solid support area 3, the overhang area 2, and the adhesive forming allowance compensation area 4, powder is laid layer by layer from bottom to top. The fusion mechanism 5 is used to perform in-situ melting and solidification of the metal powder at the layup processing positions corresponding to the solid support area 3 and the melt solidification area 202, respectively. The adhesive spraying mechanism 6 is used to bond and solidify the metal powder at the layup processing positions corresponding to the bonding forming area 201 and the adhesive forming allowance compensation area 4, respectively, until all solid support areas 3 and overhang areas 2 of the additive manufacturing part to be processed are completed.

[0038] In this embodiment, by dividing the overhanging region 2 into a bonding forming region 201 and a melting and solidification region 202, the bonding forming region 201 can form a stable support for the metal powder in the melting and solidification region 202 when it melts and solidifies. This achieves structural self-support for the processing of the overhanging region 2, avoiding the cumbersome steps of using additional support structures in traditional methods. This effectively solves the problem of difficult support structure removal in traditional additive manufacturing. In addition, by designing an adhesive forming allowance compensation region 4 at the bottom of the bonding forming region 201, the vertical height of the adhesive forming allowance compensation region 4 not only ensures the difference between the loose density of the metal powder and the density of the corresponding metal material, avoiding dimensional deviations during the subsequent sintering process after the part to be processed is printed, but also further improves the accuracy and overhanging surface quality of the overhanging region 2 under conditions without external support, while ensuring the stability and support strength of the bonding forming region 201.

[0039] In this embodiment, the thickness of a single forming layer in the solid support region 3 of the additively manufactured part during the additive manufacturing process ranges from 20 to 60 μm. The thickness of a single forming layer in the bonding forming region 201 and the adhesive forming allowance compensation region 4 during processing is 40 to 120 μm.

[0040] Example 2

[0041] See Figures 1-3This embodiment uses the laser printing process of a large-format overhanging structural part as an example to describe in detail the process of the unsupported powder bed additive manufacturing method for the large-format overhanging area of ​​the present invention. The large-format overhanging structural part is made of GH3635 alloy, and the overhanging portion has a size of 60mm. This embodiment uses a powder bed additive manufacturing device 1 that combines binder and laser. A 500W 1070nm wavelength continuous wave fiber laser is selected as the laser source. An xy galvanometer scanner guides the laser beam, and an F-θ lens is used for focusing to selectively melt metal powder particles at specific locations. The device is equipped with a binder spraying mechanism 6, with nozzles working together for efficient spraying, achieving a printing resolution of 1200dpi.

[0042] The corresponding forming method flow is as follows:

[0043] Step 1: Based on the arrangement and position of the model of the part to be processed on the powder bed 1 of the additive manufacturing equipment, identify the overhang area 2 and the solid support area 3 of the additive manufacturing part. The overhang area 2 is the part structure area with an overhang angle of 0 to 20° and a maximum length of the overhang structure projected onto the upper surface of the powder bed 1 of ≥30mm. The solid support area 3 is other solid structure areas besides the overhang area 2.

[0044] The model of the part to be processed in this embodiment is as follows: Figure 1 As shown, it includes a lower vertical section and an upper horizontal section. The horizontal section is a cantilever structure, with its bottom surface forming a 0° angle with the horizontal plane. According to... Figure 2 The arrangement is designed to identify the hanging area 2 and the solid support area 3.

[0045] Step 2: Divide the suspended area 2 from bottom to top into a bonding and forming area 201 and a melting and solidification area 202 along the vertical height direction of the part model to be processed on the powder bed 1;

[0046] In this embodiment, the suspended region 2 is divided vertically into a bonding and forming region 201 and a melting and solidification region 202.

[0047] Step 3: Design an adhesive forming allowance compensation area 4 on the lower surface of the bonding forming area 201. The vertical height of the adhesive forming allowance compensation area 4 is obtained by analysis based on h = D(1-ρ1 / ρ), where h is the vertical height of the adhesive forming allowance compensation area 4, D is the vertical height of the bonding forming area 201, ρ1 is the loose density of the metal powder, and ρ is the density of the metal material corresponding to the metal powder.

[0048] In this embodiment, GH3536 metal powder with a particle size of 15-53 μm was selected for processing, and the loose packing density of the metal powder was measured to be 4.1 g / cm³. 3 The material density of the metal is 8.2 g / cm³. 3In addition, the metal powder in the solid support area 3 is melted and solidified in situ by spreading powder layer by layer on the powder bed 1 and using laser scanning to melt and form the powder. The laser scanning parameters are set as follows: the thickness of a single forming layer is 0.04 mm, the laser power is 275 W, the scanning speed is 980 mm / s, the scanning interval is 0.1 mm, and the interlayer rotation angle is 67°.

[0049] In this embodiment, the vertical height of the bonding forming area 201 is greater than or equal to four times the thickness of a single forming layer of the solid support area 3 of the part to be processed in the additive manufacturing process. Based on the above data, the vertical height of the bonding layer can be set to 0.16 mm, and thus the vertical height of the adhesive forming allowance compensation area 4 is 0.08 mm.

[0050] Step 4: Based on the positional relationship between the solid support area 3, the overhang area 2, and the adhesive forming allowance compensation area 4, powder is laid layer by layer from bottom to top. A fusion mechanism 5 is used to perform in-situ melting and solidification of the metal powder at the layup positions corresponding to the solid support area 3 and the melt-solidification area 202. An adhesive spraying mechanism 6 is used to bond and solidify the metal powder at the layup positions corresponding to the bonding forming area 201 and the adhesive forming allowance compensation area 4, until all solid support areas 3 and overhang areas 2 of the additive manufacturing part are processed. The processing method for the solid support area 3 is a conventional processing technique and will not be described in detail here. In this embodiment, the processing flow of the adhesive forming allowance compensation area 4 and the overhang area 2 is as follows:

[0051] Step 4.1: When the scanned part cross section reaches the position corresponding to the lower surface of the adhesive forming allowance compensation area 4, the adhesive spraying mechanism 6 is used to scan the metal powder at the corresponding layup processing position and perform thermal curing to form the first adhesive curing layer.

[0052] Step 4.2: Powder is laid layer by layer on the surface of the first bonded and cured layer. For each layer, the metal powder at the corresponding layup location is scanned by the adhesive spraying mechanism 6 and then thermally cured until the adhesive forming allowance compensation area 4 and the adhesive forming area of ​​the overhang area 2 are formed. The structural strength and stiffness formed by the bonded and cured layer are used to resist the thermal stress deformation when laser forming is continued above this area.

[0053] In this embodiment, water-based adhesive BW06SO is selected, the scanning speed is set to 500 mm / s, and the thickness of the single-layer powder layer in the adhesive forming zone and the adhesive forming allowance compensation zone 4 is 0.08 mm.

[0054] Step 4.3: After the bonding forming zone 201 has cured, the powder bed 1 descends by a first layer thickness of 0.04 mm to spread powder (which can be smoothed using a scraper 7). The metal powder at the current layering processing position is scanned by a laser with 40% of the design line energy of the solid support zone 3, and sintered to form a first sintered thin layer. The first sintered thin layer is located on the top layer of the bonding forming zone 201. The parameters are set as follows: laser power of 110W, scanning speed of 980mm / s, scanning interval of 0.1mm, and interlayer rotation angle of 67°.

[0055] Step 4.4: The powder bed 1 descends by 0.04 mm to spread powder. The metal powder at the current layup position is scanned by a laser with 60% of the line energy of the solid support region 3. The powder is sintered to form a second sintered thin layer, which is located on top of the first sintered thin layer. The parameters are set as follows: laser power is 165W, scanning speed is 980mm / s, scanning interval is 0.1mm, and interlayer rotation angle is 67°.

[0056] Step 4.5: The powder bed 1 descends by 0.04 mm to spread powder. The metal powder at the current layup position is scanned by a laser with 80% of the line energy of the solid support area 3. The powder is sintered to form a third sintered thin layer. The third sintered thin layer is located on top of the second sintered thin layer. The parameters are set as follows: laser power is 220W, scanning speed is 980mm / s, scanning spacing is 0.1mm, and interlayer rotation angle is 67°.

[0057] Step 4.6: Layer by layer powder is laid on top of the third sintered thin layer. The metal powder at the current layup processing position is scanned layer by layer by a laser with the line energy designed for the solid support area 3. The molten solidification area 202 is connected with the adjacent solid support area 3 to form a single-layer cross-section of the part to be processed. The parameters are set as follows: laser power is 275W, scanning speed is 980mm / s, and scanning interval is 0.1mm. Step 4.6 is repeated until the processing of the remaining overhanging area 2 is completed.

[0058] Step 5: After all solid support areas 3 and overhang areas 2 of the additive manufacturing part to be processed are processed, the powder is cleaned off the removed parts, followed by degreasing and sintering treatment. The degreasing and sintering treatment parameters are: heating to 700℃ at 8℃ / min under vacuum and holding for 1h; then heating to 1170℃ at 8℃ / min and holding for 2h, followed by cooling in the form of furnace cooling.

[0059] Step 6: After degreasing and sintering, the parts are subjected to hot isostatic pressing at 1175℃ / 160MPa to obtain a high-density metallurgical structure.

[0060] In this embodiment, the bonding forming area 201 or the adhesive forming allowance compensation area 4 at the same vertical height position are preferentially formed. Based on this, in order to ensure that the bonding forming area 201 shrinks vertically in the subsequent sintering process, this embodiment adopts an embedded connection structure between the solid area and the adhesive forming area. That is, during the processing of the solid support area 3, at the position where the solid support area 3 is in lateral contact with the bonding forming area 201 and the adhesive forming allowance compensation area 4, the forming layer of each solid support area 3 is offset by a spot distance in the direction of the corresponding bonding forming area 201 or the adhesive forming allowance compensation area 4. Taking a certain vertical section on the bonding forming area 201 as the XOY plane, the vertical straight line perpendicular to the XOY plane and passing through the origin O as the Z axis, and the layer stacking direction as the positive direction of the Z axis, the O-XYZ spatial rectangular coordinate system is adopted. During the sintering process after laser forming is completed, if there are no surrounding restrictions, the bonding forming area 201 will shrink in the three directions of OX, OY, and OZ during the sintering process. By biasing the laser spot, the laser melting area is embedded into the bonding forming area 201, increasing the restriction in the OX\OY direction; in the OZ direction, there is only restriction at the top and no restriction at the bottom, and it will shrink along the OZ. The shrinkage amount is compensated by the adhesive forming allowance compensation area 4 to ensure that the size of the overhanging area 2 meets the design requirements.

[0061] 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 protection scope of the present invention.

Claims

1. A method for unsupported powder bed additive manufacturing of large-format overhanging areas, characterized in that, include: Based on the arrangement and position of the model of the part to be processed on the powder bed of the additive manufacturing equipment, the overhang area and solid support area of ​​the additive manufacturing part are identified. The overhang area is the part structure area with an overhang angle of 0 to 20° and a maximum length of the overhang structure projected onto the surface of the powder bed ≥ 30 mm. The solid support area is other solid structure areas besides the overhang area. The overhanging area is divided from bottom to top into a bonding and forming zone and a melting and solidification zone along the vertical height direction of the part model to be processed in the powder bed; A binder forming allowance compensation area is designed on the lower surface of the bonding forming area. The vertical height of the binder forming allowance compensation area is obtained by analysis based on h=D(1-ρ1 / ρ), where h is the vertical height of the binder forming allowance compensation area, D is the vertical height of the bonding forming area, ρ1 is the loose density of the metal powder, and ρ is the density of the metal material corresponding to the metal powder. Based on the positional relationship between the solid support area, the overhang area, and the adhesive forming allowance compensation area, powder is laid layer by layer from bottom to top. A fusion mechanism is used to melt and solidify the metal powder at the layup processing positions corresponding to the solid support area and the melt solidification area in situ. An adhesive spraying mechanism is used to bond and solidify the metal powder at the layup processing positions corresponding to the bonding forming area and the adhesive forming allowance compensation area, until all solid support areas and overhang areas of the additive manufacturing part to be processed are completed.

2. The large-format unsupported powder bed additive manufacturing method for overhanging areas according to claim 1, characterized in that, The fusion mechanism is a laser melting device.

3. The large-format unsupported powder bed additive manufacturing method for overhanging areas according to claim 2, characterized in that, The vertical height of the bonding forming zone is greater than or equal to four times the thickness of a single forming layer in the solid support area of ​​the part to be processed during the additive manufacturing process.

4. The large-format unsupported powder bed additive manufacturing method for overhanging areas according to claim 2, characterized in that, The method of in-situ melting and solidifying the metal powder at the layup processing position of the solid support region using a fusion mechanism includes: laying powder layer by layer on a powder bed, scanning the metal powder at each layup processing position layer by layer with a laser of the designed line energy of the solid support region, and completing the processing of the solid support region.

5. The large-format unsupported powder bed additive manufacturing method for overhanging areas according to claim 4, characterized in that, The bonding forming area or adhesive forming allowance compensation area at the same vertical height position shall be formed preferentially.

6. The large-format unsupported powder bed additive manufacturing method for overhanging areas according to claim 5, characterized in that, During the processing of the solid support area, at the position where the solid support area is in lateral contact with the bonding forming area and the adhesive forming allowance compensation area, the forming layer of each solid support area is offset by a light spot distance towards the corresponding bonding forming area or adhesive forming allowance compensation area.

7. The method for unsupported powder bed additive manufacturing of large-format overhanging areas according to claim 2, characterized in that, The processing method for the melt-solidified zone of the overhanging region includes: After the bonding forming zone is cured, the powder bed is lowered by a first layer thickness value, powder is spread, and the metal powder at the current layup processing position is scanned by a laser with 40% of the design line energy of the solid support zone, and sintered to form a first sintered thin layer, which is located on the top layer of the bonding forming zone. The powder bed is lowered by a first layer thickness value, powder is spread, and the metal powder at the current layering processing position is scanned by a laser with 60% of the design line energy of the solid support area, and sintered to form a second sintered thin layer, which is located on top of the first sintered thin layer. The powder bed is lowered by a first layer thickness value, powder is spread, and the metal powder at the current layering processing position is scanned by a laser with 80% of the design line energy of the solid support area, and sintered to form a third sintered thin layer, which is located on top of the second sintered thin layer; Powder is laid layer by layer above the third sintered thin layer. The metal powder at the current layup position is scanned layer by layer by a laser with the line energy of the solid support area. The molten solidification area is connected with the adjacent solid support area to form a single-layer cross-section of the part to be processed, until the processing of the remaining overhang area is completed.

8. The large-format unsupported powder bed additive manufacturing method for overhanging areas according to claim 2, characterized in that, During the scanning and processing of the solid support area and the melt-solidified area, the interlayer rotation angle between two adjacent forming layers is 67°.

9. The method for large-format unsupported powder bed additive manufacturing of overhanging regions according to any one of claims 1-8, characterized in that, The thickness of a single forming layer in the solid support area of ​​an additively manufactured part ranges from 20 to 60 μm during the additive manufacturing process.

10. The method for large-format unsupported powder bed additive manufacturing of overhanging regions according to any one of claims 1-8, characterized in that, The thickness of a single forming layer during the processing of the bonding forming zone and the adhesive forming allowance compensation zone is 40-120μm.

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