Additive processing device and method based on 3D powder printing

Abstract

The present invention relates to the field of additive manufacturing technology, and specifically to an additive processing device and method based on 3D powder printing, including an additive processing area surrounded by a sealed box, wherein a carrying platform, a positioner, a molding cylinder, a powder supply system, a laser, and a powder scraping component are arranged in the additive processing area, the sealed box is filled with an inert gas, and is provided with an air inlet and an exhaust port, the air inlet and the exhaust port are connected to a gas circulation system, so that the additive processing area is in an inert gas protective atmosphere; the present invention arranges the molding cylinder to be driven by a positioner, can rotate continuously along its axis Z axis, and can rotate along a Y axis perpendicular to the Z axis, so that the flexibility of the molding cylinder is better, so that large-sized complex workpieces can be processed and formed; the flippable design of the molding cylinder of the present invention is conducive to dumping the printing powder in the molding cylinder, and the use of printing powder can be reduced by replacing the powder of the printed layer with filling powder.

Description

Technical Field

[0001] The present invention relates to the field of additive manufacturing technology, and in particular to an additive manufacturing device and method based on 3D powder printing. Background Art

[0002] Selective laser melting is an additive manufacturing technology that uses computer-aided design and manufacturing, based on the principle of "discrete-layered-accumulated". It uses a high-energy laser beam to directly melt metal powder into fully dense three-dimensional parts. The forming process does not require a mold and is not limited by the complexity of the part structure. The unmelted powder can serve as a supporting material, thereby obtaining metal functional parts with metallurgical bonding, high precision, and high structural complexity. It has broad application prospects.

[0003] The specific principle is roughly as follows: before the laser beam starts scanning, the powder spreading device first pushes the metal powder flat onto the base plate of the forming cylinder, and the laser beam then follows the filling scanning line of the current layer to select and melt the powder on the base plate to process the current layer, and then the base plate of the forming cylinder drops a layer thickness, and the powder cylinder rises a certain thickness. The powder spreading device then spreads the metal powder on the processed current layer, and the equipment transfers the data of the next layer contour for processing, and so on, layer by layer, until the entire part is processed. The entire processing process is carried out in a processing room protected by inert gas to prevent the metal from reacting with other gases at high temperatures.

[0004] At present, the forming cylinder of 3D powder printing is generally fixed, which restricts the flexibility of powder printing. As 3D printed workpieces become larger and more complex, the limitations of 3D powder printing become more and more obvious. Therefore, how to cope with large-scale and complex processing needs has become an urgent problem to be solved. Summary of the invention

[0005] According to a first aspect of the present invention, an additive processing device based on 3D powder printing is proposed, comprising an additive processing area surrounded by a sealed box, wherein a carrying platform, a positioner, a forming cylinder, a powder supply system, a laser, and a powder scraping component are arranged in the additive processing area, the sealed box is filled with an inert gas, and is provided with an air inlet and an exhaust port, wherein the air inlet and the exhaust port are connected to a gas circulation system, so that the additive processing area is in an inert gas protection atmosphere;

[0006] The powder supply system includes an additive powder bin, which spreads powder layer by layer into the forming cylinder through a powder scraping component, and the laser sinters the additive powder according to a predetermined path to form a main structure;

[0007] The positioner is installed on the carrying platform, the forming cylinder is fixed to the load surface of the positioner, and can be driven by the positioner to continuously rotate around the axis Z of the forming cylinder and the Y axis perpendicular to the Z axis.

[0008] Preferably, the positioner includes a first support frame, a second support frame and a rotating table. The second support frame is arranged on the inner side of the first support frame and can be driven by a flipping drive to flip along the Y-axis relative to the first support frame. The rotating table is fixed to the second support frame, and the forming cylinder is connected to the upper end of the rotating table so that the forming cylinder can rotate around the axis of the forming cylinder relative to the second support frame.

[0009] Preferably, the second support frame is configured to be U-shaped, a mounting plate is provided on the rotating table, and the forming cylinder is detachably connected to the mounting plate.

[0010] Preferably, the power supply lines of the positioner and the forming cylinder are integrated into a bundle, and the power supply connectors form a socket strip, which is pluggable and connected to the power supply socket in the sealing box.

[0011] Preferably, the first support frame is provided with a first power supply line, the second support frame is provided with a second power supply line, the forming cylinder is provided with a third power supply line, a first conductive slip ring is provided at the hinge of the first support frame and the second support frame, and the rotating table is provided with a second conductive slip ring, the first power supply line and the second power supply line are electrically connected through the first conductive slip ring, and the second power supply line and the third power supply line are electrically connected through the second conductive slip ring, so that the positioner can continue to rotate along the Z axis and / or flip along the Y axis while still maintaining power supply to the external power supply.

[0012] Preferably, it also includes a laser cladding component, which is configured to be driven by a robot and move around the main structure formed on the molding cylinder substrate to repair the main structure or to add material to the surface of the main structure to form a supporting structure and a suspended structure.

[0013] Preferably, it further comprises a subtractive processing area and a track structure, wherein a first end of the track structure extends to the additive processing area, and a second end extends to the subtractive processing area;

[0014] The carrying platform can move on the track structure to travel between the additive processing area and the subtractive processing area;

[0015] The subtractive processing area is provided with a processing center for performing subtractive processing on the workpiece formed in the forming cylinder in the subtractive processing area.

[0016] Preferably, the powder supply system also includes a filling powder silo, which spreads a predetermined thickness of filling powder into the forming cylinder through a powder scraping component, the additive powder silo is provided with additive powder, and the filling powder silo is provided with filling powder, and the particle size of the filling powder is larger than that of the additive powder.

[0017] Preferably, a powder screening component is provided on one side of the forming cylinder. When the forming cylinder is tilted by the positioner, the mixed powder in the forming cylinder falls into the powder screening component and is screened into additive powder and filling powder.

[0018] Preferably, it also includes a powder suction component, which is arranged in the additive processing area and is used to suck the powder around the forming cylinder and the formed workpiece and discharge it to the powder screening component when the forming cylinder pours the powder.

[0019] Preferably, the powder screening component includes a screen and a collecting bucket, wherein the screen is arranged on the upper part of the collecting bucket, so that powder smaller than the screen holes of the screen falls into the collecting bucket, and powder larger than the screen holes of the screen remains on the surface of the screen, wherein the screen is arranged at an angle, and a first row of powder openings is provided at the lower end of the screen, and a second row of powder openings is provided at the bottom of the collecting bucket.

[0020] Preferably, the device further includes a first powder receiving cylinder and a second powder receiving cylinder, wherein the first powder receiving cylinder is connected to the first powder discharge port, and the second powder receiving cylinder is connected to the second powder discharge port, the first powder receiving cylinder is used to supply the additive powder bin, and the second powder receiving cylinder is used to supply the filling powder bin.

[0021] Preferably, it also includes a first powder sucker and a second powder sucker, each of which is provided with a powder suction pipeline, a powder discharge pipeline and an exhaust pipeline, the powder suction pipeline of the first powder sucker is connected to the first powder receiving barrel, the exhaust pipeline of the first powder sucker is connected to an aeration box, the powder discharge pipeline of the first powder sucker is connected to an additive powder silo, the powder suction pipeline of the second powder sucker is connected to the second powder receiving barrel, the exhaust pipeline of the second powder sucker is connected to the aeration box, and the powder discharge pipeline of the second powder sucker is connected to a filling powder silo.

[0022] The second aspect of the present invention proposes a technical solution, an additive processing method based on 3D powder printing, including an alternating continuous process and an interruption process. In the continuous process, the printing process is divided into several layers according to the size of the workpiece, and each layer corresponds to a slice structure. The powder bin of the additive powder controls the amount of powder falling of each layer, and the powder is spread on the surface of the substrate by a scraper and sintered by a laser according to a predetermined path to form a single-layer slice structure; and each layer of the slice structure is printed layer by layer from the bottom to the top until a complete workpiece is formed;

[0023] Among them, the interruption process occurs after any layer of the slice structure is processed and formed in the continuous process. During the interruption process, the forming cylinder is flipped over to pour out the additive powder, and then the forming cylinder is restored to a horizontal position, and the powder is backfilled to the height layer before the interruption, and the interruption process ends.

[0024] Preferably, the poured out additive powder is collected and supplied to an additive powder bin as printing material used for the continued process after the interruption process.

[0025] Preferably, the particle size of the backfilled filling powder is larger than the particle size of the additive powder.

[0026] Preferably, after backfilling the filling powder, the backfilled filling powder layer is pressurized by a pressing plate to compact the backfilled filling powder layer.

[0027] Preferably, it further includes a bridging process, wherein the bridging process is in an interrupted process, and the workpiece to be added includes a suspended structure, wherein the suspended structure is defined as a state structure in which the lower part of the structure is not connected to the main structure, or the angle formed by the bottom contour inclination and the substrate is less than 40°, and when the bottom of the suspended structure has a support, it belongs to the main structure;

[0028] The bridging process step comprises:

[0029] Step Qa, dumping the additive powder in the molding cylinder to flip the molding cylinder at a predetermined angle;

[0030] Step Qb, adding material to form a support structure parallel to the substrate on the surface of the main structure at a height layer corresponding to the bottom of the suspended structure;

[0031] Step Qc, adding material to the surface of the support structure to form a suspended structure until the suspended structure is connected to the main structure;

[0032] Wherein, in step Qb, the angle between the support structure and the horizontal plane is greater than 40°.

[0033] Preferably, in step Qb, the supporting structure is formed by laser cladding; and in step Qc, the suspended structure is formed by laser cladding or powder printing.

[0034] Preferably, it also includes a subtractive processing process, wherein the subtractive processing process is in an interrupted process, and the subtractive processing process includes the following steps:

[0035] Step Ja, dumping the additive powder in the molding cylinder to flip the molding cylinder at a predetermined angle;

[0036] Step Jb: Remove the support structure through a machining center.

[0037] The third aspect of the present invention provides a technical solution, a powder-laying printing additive processing method, wherein the printing process is divided into several layers according to the size of the workpiece, the layer height H of each layer is the same, and each layer corresponds to a slice structure, the amount of powder falling of each layer is controlled by the additive powder bin, and the powder is spread on the surface of the substrate by a scraper and sintered by a laser according to a predetermined path to form a single-layer slice structure; and each layer of the slice structure is printed layer by layer from the bottom to the top until a complete workpiece is formed;

[0038] After each workpiece with a preset layer height is formed by adding materials, powder pressing is performed, and the steps of powder pressing include:

[0039] Step Ya, the substrate is lowered to a powder pressing height, the powder pressing height is greater than or equal to a layer height H, and powder is spread, and the powder spreading thickness is greater than the powder pressing height;

[0040] Step Yb, the pressing plate moves downward from above the forming cylinder to press the powder on the surface of the forming cylinder;

[0041] Step Yc: the pressing plate is reset, the substrate is raised to the powder pressing height, and the scraper scrapes off the excess powder to complete the powder pressing.

[0042] Compared with the prior art, the additive processing device and method based on 3D powder printing of the present invention have the following significant advantages:

[0043] The additive processing device based on 3D powder printing proposed in the present invention arranges the forming cylinder to be driven by a positioner, can continuously rotate along its axis Z axis, and can rotate along the Y axis perpendicular to the Z axis, so that the flexibility of the forming cylinder is better, which is conducive to the combination of powder spreading additive with other additive or subtractive methods, so that large-sized complex workpieces can be processed and formed; at the same time, combined with the flippable design of the forming cylinder, it is conducive to dumping the additive powder in the forming cylinder. By replacing the powder of the printed layer with filling powder, and recovering the dumped additive powder as the supply powder of the unprinted layer, the use of additive powder can be reduced, especially for large-sized workpieces.

[0044] Therefore, the present invention combines a reversible forming cylinder with a laser cladding device. The laser cladding device can repair cracks and surface deformations on the surface of parts formed by coupled printing, thereby overcoming the problem of printing failure caused by defects such as deformation, tool collision, and cracks that are prone to occur in parts in current large-size powder printing. Through the reversible design of the forming cylinder, the angle of the supporting surface is changed, and the laser cladding device can add material to the surface of the main structure to form a supporting structure, and use the supporting structure as a supporting basis for adding material to the suspended structure, and use a bridging method to change the current support form for printing the suspended structure.

[0045] In combination with the above embodiments, the present invention combines a flippable forming cylinder with a machining center. Due to the angular deflection of the forming cylinder, the machining center has more machining angles, so that surface machining of workpieces with more complex shapes can be achieved. At the same time, the power supply of the forming cylinder and the positioner is set to be plug-in, and a conductive slip ring is used for power supply, so that the forming cylinder can maintain power supply under the conditions of large-range movement of additive and subtractive materials and continuous rotation of multiple axes along the Z axis and Y axis. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] The drawings are not intended to be drawn to scale. In the drawings, each identical or nearly identical component shown in various figures may be represented by the same reference numeral. For clarity, not every component is labeled in every figure. Embodiments of various aspects of the present invention will now be described by way of example and with reference to the accompanying drawings, in which:

[0047] Figure 1 It is a structural schematic diagram of an additive processing device based on 3D powder printing shown in the invention;

[0048] Figure 2 is a top view of the powder screening component shown in the present invention;

[0049] Figure 3 It is a schematic diagram of the structure of the circuit buried wire in the positioner shown in the present invention;

[0050] Figure 4 It is a schematic diagram of the forming cylinder shown in the present invention in a horizontal state;

[0051] Figure 5 It is a schematic diagram of the forming cylinder in the flipping state shown in the present invention;

[0052] Figure 6 It is a schematic diagram of the forming cylinder in the process of powder spreading and printing to form the main structure shown in the present invention;

[0053] Figure 7 It is a schematic diagram of the molding cylinder shown in the present invention in a state of pouring powder;

[0054] Figure 8 It is a schematic diagram of forming a supporting structure and a suspended structure by cladding on the surface of a main structure shown in the present invention;

[0055] Fig. 9 is a schematic diagram of subtractive processing of a support structure shown in the present invention;

[0056] Fig.10 is a schematic diagram of backfill powder shown in the present invention;

[0057] Fig.11 is a schematic diagram of flattening backfill powder shown in the present invention;

[0058] Fig.12 It is a schematic diagram of the present invention showing the process of flattening and refilling powder and then continuing to spread powder for printing;

[0059] Fig.13 It is a schematic diagram of using a powder collecting tube to recover powder according to the present invention;

[0060] Fig.14 It is a schematic diagram of a powder spreading method shown in the present invention. DETAILED DESCRIPTION

[0061] In order to better understand the technical content of the present invention, specific embodiments are given and described as follows in conjunction with the accompanying drawings.

[0062] In the current 3D powder printing, since the forming cylinder is fixed and only the internal base plate moves up and down, the degree of freedom is low, and the formed workpiece further limits the secondary processing angle of the workpiece by the external processing equipment. Therefore, it is difficult to perform secondary additional processing in powder printing. However, powder printing has the advantages of high precision and the ability to process large-sized workpieces. Therefore, how to process large-sized, high-precision, and complex-shaped workpieces has become an urgent problem to be solved.

[0063] In response to the above-mentioned problems, the first aspect of the present application proposes an additive processing device based on 3D powder printing, in which a positioner is arranged at the bottom of the forming cylinder so that the forming cylinder can be tilted, which is beneficial for reserving the operating space and angle of the tool during machining.

[0064] Based on the interrupted powder spreading process in the prior art, re-processing requires re-powder spreading. The second aspect of the present application adopts a powder filling method to replace the additive powder and fill the processed height layer with filling powder to reduce the amount of powder used.

[0065] In the third aspect of the present invention, by combining with laser cladding and / or machining subtractive processing, laser cladding is used to quickly add materials to the support structure, and then 3D printing is used to process on the added support structure, and finally the machining center uses subtractive processing to form the final product, making it possible to process large-size, high-precision, and complex-shaped workpieces.

[0066] In the fourth aspect of the present invention, during the 3D printing process, the flipping of the forming cylinder is utilized to change the original angle of the workpiece, thereby creating an activity space that is conducive to secondary processing. For example, a supporting platform is first manufactured by means of a bridging method, and then a designed suspended component is made on the supporting platform. Finally, after the suspended component is formed, the supporting platform is removed by machining, and the component shape or surface treatment is further refined to achieve the forming of complex parts.

[0067] [Additive processing device based on 3D powder printing]

[0068] Combination Figure 1 As shown, the first aspect of the present invention proposes a technical solution, an additive processing device based on 3D powder printing, including an additive processing area 101 surrounded by a sealed box 100, and the additive processing area is provided with a carrying platform 20, a positioner 40, a forming cylinder 30, a powder supply system, a laser 13, and a powder scraping component 60.

[0069] Among them, the sealed box 100 is filled with inert gas to protect the metal powder from being oxidized. Furthermore, during the laser additive manufacturing process, due to the generation of heat and smoke, it is necessary to continuously introduce inert gas into the sealed box 100 to maintain the flow of air. Therefore, an air inlet 104 and an exhaust port 103 are also provided on the sealed box 100, wherein a gas circulation system is connected between the air inlet 104 and the exhaust port 103, and the gas circulation system includes a filtering device and a heat exchange device, and the purpose is to cool the gas and clean the gas.

[0070] The specific form of 3D powder printing is that the additive powder bin 52 spreads powder layer by layer into the forming cylinder 30 through the powder scraping component 60, and the laser 13 sinters the additive powder according to a predetermined path to form the main structure. It can be seen that this layer-by-layer powder spreading method determines that the forming cylinder 30 cannot be tilted at an angle, otherwise the powder will spill out, and this also limits the secondary processing form of the workpiece formed by additive. For example, it is impossible to form an extended structure with an inclination angle less than 40° on the surface of the workpiece. When the inclination angle is too large, such as an 80° angle with the substrate, there is no support at the bottom, and the powder will melt into disordered spheres during additive printing, which cannot be effectively combined into a fixed structure. In addition, due to the interference of the workpiece shape, the machining tool does not have more angles because the forming cylinder 30 is at a fixed angle.

[0071] Therefore, the present invention aims to improve the flexibility of the forming cylinder, especially to control the flipping of the forming cylinder 30. Optionally, the positioner 40 is installed on the carrying platform 20, and the forming cylinder 30 is fixed to the load surface of the positioner 40, and can be driven by the positioner 40 to continuously rotate around the axis Z of the forming cylinder and the Y axis perpendicular to the Z axis.

[0072] In this way, the forming cylinder has better flexibility, which is conducive to combining powder laying additive manufacturing with other additive or subtractive methods, so that large-sized and complex workpieces can be processed and formed.

[0073] Positioner

[0074] In an optional embodiment, in combination with Figure 3-5 As shown, the positioner 40 includes a first support frame 41, a second support frame 42 and a rotating table 44. The second support frame 42 is arranged on the inner side of the first support frame 41, and can be driven by a flipping driver 43 to flip along the Y-axis relative to the first support frame 41. The rotating table 44 is fixed to the second support frame 42, and the forming cylinder 30 is connected to the upper end of the rotating table 44, so that the forming cylinder 30 can rotate around the axis of the forming cylinder 30 relative to the second support frame 42.

[0075] In a preferred embodiment, the first support frame 41 and the second support frame 42 are configured in a U shape, and the rotating platform 44 is located at the bottom of the second support frame 42. In this way, the first support frame 41, the second support frame 42 and the forming cylinder 30 have a compact structure, which can reduce the overall volume of the equipment.

[0076] Furthermore, a mounting plate 441 is provided at the upper end of the rotating table 44, and the forming cylinder 30 is detachably mounted on the mounting plate 441, so that the forming cylinder 30 of different sizes can be reasonably replaced according to the size of the workpiece to be produced.

[0077] Furthermore, in order to meet the power supply requirements of the forming cylinder 30, especially when the forming cylinder 30 continuously rotates along the Z axis and / or flips along the Y axis, it still maintains power supply with an external power source.

[0078] The first support frame 41 and the second support frame 42 should be provided with embedded lines 45, wherein the first support frame 41 is provided with a first power supply line, the second support frame 42 is provided with a second power supply line, the forming cylinder 30 is provided with a third power supply line, a first conductive slip ring is provided at the hinge of the first support frame 41 and the second support frame 42, the rotating table 44 is provided with a second conductive slip ring, the first power supply line and the second power supply line are electrically connected through the first conductive slip ring, and the second power supply line and the third power supply line are electrically connected through the second conductive slip ring.

[0079] In this way, the two relatively rotating components can maintain continuous electrical connection through the provision of the conductive slip ring.

[0080] Specifically, the third power supply circuit supplies power to the forming cylinder 30, the second power supply circuit supplies power to the forming cylinder 30 and the rotating table 44, and one end of the first power supply circuit is connected to the flip driver 43, and the second end is connected to the external power supply.

[0081] In other embodiments, the power supply lines of the positioner 40 and the forming cylinder 30 are integrated into a bundle, and the power supply connectors form a socket strip, which is pluggable and connected to the power supply socket in the sealing box.

[0082] Furthermore, a drag chain is provided at the bottom of the carrying platform 20 , and the drag chain is used to connect the first power supply line, so that the carrying platform 20 remains powered when traveling back and forth between the additive processing area 101 and the subtractive processing area 102 .

[0083] In an optional embodiment, a plug connector 451 is provided at the end of the first power supply line, and the plug connector 451 is fixed to the side of the first support frame 41, and a power plug is provided on the sealing box 100. When the plug connector 451 and the power plug are connected, power is supplied to the forming cylinder 30 and the positioner 40.

[0084] Furthermore, since the forming cylinder 30 and the positioner 40 do not require power supply during transfer, power plugs are respectively arranged at the extreme positions of the parking of the supporting platform 20, such as the position in the additive processing area 101 and the position in the subtractive processing area 102. When the supporting platform 20 moves to the additive processing area 101 and the subtractive processing area 102, the power plug and the plug connector 451 are docked.

[0085] Combination with laser cladding components

[0086] Furthermore, since parts are prone to deformation, tool collision, cracks and other defects during large-scale powder printing, and the defects are hidden in the powder and cannot be observed during powder printing, but are easily observed by flipping the forming cylinder 30 to dump the powder, and can be repaired by secondary processing of laser cladding parts, the equipment is also provided with a laser cladding part 14, which is configured to be driven by a robot and move around the main structure formed on the substrate 32 of the forming cylinder 30 to repair the main structure or to add material to the surface of the main structure to form a supporting structure and a suspended structure.

[0087] Preferably, after the substrate 32 rises to the position where the defect of the workpiece is exposed, the laser cladding component 14 is driven by the robot to repair the surface cracks.

[0088] The laser cladding component 14 includes a laser cladding head, and surface processing can be performed by wire feeding or powder feeding cladding.

[0089] Integration with machining center

[0090] Since the precision of laser cladding processing is poor, a processing center is also required to perform fine surface processing. Therefore, the equipment also includes a subtractive processing area 102 and a track structure 11. The first end of the track structure 11 extends to the additive processing area 101, and the second end extends to the subtractive processing area 102.

[0091] The carrying platform 20 can move on the track structure 11 to travel between the additive processing area 101 and the subtractive processing area 102;

[0092] The subtractive processing area 102 is provided with a machining center 16 for performing subtractive processing on a workpiece formed in the forming cylinder 30 in the subtractive processing area 102 .

[0093] Since the forming cylinder 30 can be driven by the positioner 40 to rotate, especially to rotate along the Z-axis direction, the operability of machining can be greatly improved.

[0094] In addition, the introduction of machining centers allows cladding processing to have a wider range of applications. For example, currently powder printing cannot print unsupported suspended structures, and supports must be formed by bottom growth, but it is also difficult to remove the supports. By cladding additives to form support structures, and then additively forming suspended structures on the support structures, suspended structures can be formed by additives at any height, allowing more complex workpieces to be formed by powder printing.

[0095] In a specific embodiment, in combination Figure 6-12 As shown, for example, the steps for printing the suspended structure shown in the figure are as follows:

[0096] The first step is to combine Figure 6 As shown, 3D powder printing: the scraper stores a predetermined amount of powder and spreads the powder on the upper end surface 311 of the forming cylinder 30, and the laser 13 uses a scanning galvanometer to make the laser beam sinter the additive powder 521 along a predetermined trajectory to form a prefabricated structure. When the additive reaches a predetermined thickness and a suspended structure is required (the height layer at this time is defined as the first height layer);

[0097] Step 2: Pour the powder: Combine Figure 7 As shown, the forming cylinder 30 raises the substrate to the highest point, and the positioner 40 controls the forming cylinder 30 to rotate a certain angle to dump the powder;

[0098] Step 3: Support layer printing: Combine Figure 8 As shown, the forming cylinder 30 is flipped so that the structure with the new material is kept at an angle of less than 40° with the horizontal plane, and the laser cladding component 14 is used to add material on the surface of the prefabricated structure to form a supporting layer, and then the substrate is controlled to return to a horizontal state, and a suspended structure is added on the basis of the supporting layer (wherein the precision requirement of the suspended structure is not high, and the outline is larger than the outline of the target structure);

[0099] Optionally, when the volume of the suspended structure is relatively small, the laser cladding component 14 may be used to form an additive structure on the supporting structure, for example, as shown in the figure, a square structure is reduced to form a spherical structure.

[0100] Step 4: Subtractive processing: Combination Fig. 9 As shown, the molding cylinder 30 is transferred to the subtractive processing area 102, and the cladding structure is finely processed by the machining center 16 so that its surface roughness and shape meet the product requirements, and the highest point height of the target structure is defined to be at the second height layer;

[0101] Step 5: Backfilling Powder: Combination Fig.10 As shown, the forming cylinder 30 is transferred to the additive processing area 101, and the filling powder 531 is filled to a level below the second height layer, and then the additive powder 521 is filled to a level above the second height layer, so that when printing a layer, the bottom is guaranteed to be additive powder, thereby avoiding a decrease in printing quality;

[0102] Step 6. Compact the powder: Combine Fig.11 As shown, a pressing plate 15 is used to flatten the surface to make the filled powder compact;

[0103] Step 7: 3D powder printing: Combination Fig.12 As shown, the additive powder 521 is used to print the remaining parts layer by layer until the suspended structure is encountered again, and steps 2 to 6 are repeated until the entire structure is completed.

[0104] Furthermore, in the above-mentioned embodiment, the subtractive processing area 102 is also provided with a crane system for hoisting / replacing forming cylinders of different sizes.

[0105] Powder filling design

[0106] In the above-mentioned embodiments, since the flipping of the forming cylinder involves the pouring of powder, it is necessary to backfill the poured powder to the original height before pouring. Furthermore, in order to save the use of additive powder, the backfilled powder does not participate in printing. Therefore, other powders can be used for filling. Among them, the powder is required to have a particle size different from the additive powder, high strength, and no crushing. Avoid mixing with the additive powder, and preferably use large-particle powder of the same material as the additive powder.

[0107] Optionally, the powder supply system also includes a filling powder silo 53 , which spreads a predetermined thickness of filling powder 531 into the forming cylinder 30 through a powder scraping component 60 , the additive powder silo 52 is provided with additive powder 521 , and the filling powder silo 53 is provided with filling powder 531 .

[0108] Preferably, in order to increase the backfilling speed, the particle size of the filling powder 531 is larger than the particle size of the additive powder 521 .

[0109] Furthermore, in order to recover the powder after dumping, a powder screening component 50 is provided on one side of the forming cylinder 30. When the forming cylinder 30 is driven by the positioner 40 to tilt, the mixed powder in the forming cylinder 30 falls into the powder screening component 50 and is screened into additive powder 521 and filling powder 531.

[0110] In combination with the above, the forming cylinder 30 is driven by the positioner 40 to tilt, causing the powder on the surface to pour out. It can be understood that during the intermediate processing, the pouring of powder does not completely interfere with the powder printing and bridging. When the workpiece is printed and the last powder cleaning is completed, the door of the sealed box 100 can be opened and the powder cleaning can be manually entered.

[0111] Preferably, a powder suction device can be used to suck and collect the powder remaining in the corners of the workpiece.

[0112] The powder screening component 50 is intended to separate the mixed additive powder 521 and filler powder 531 and divert them to different locations for collection.

[0113] Optionally, the powder screening component 50 includes a screen 51 and a collecting bucket 513, wherein the screen 51 is arranged on the upper part of the collecting bucket 513, so that powder smaller than the sieve holes of the screen 51 falls into the collecting bucket 513, and powder larger than the sieve holes of the screen 51 remains on the surface of the screen 51, wherein the screen 51 is arranged at an angle, and a first row of powder openings 511 is provided at the lower end of the screen 51, and a second row of powder openings 512 is provided at the bottom of the collecting bucket 513.

[0114] In a preferred embodiment, a vibration motor is connected to the screen 51 to accelerate the screening speed by vibrating the screen 51 .

[0115] In this way, powder larger than the mesh size of the sieve 51 is separated from the first row of powder openings 511 , and powder smaller than the mesh size of the sieve 51 is separated from the second row of powder openings 512 .

[0116] Example 1 of powder circulation

[0117] Combination Fig.12 As shown, optionally, a powder receiving cylinder is provided at the first powder row port 511 and the second powder row port 512 respectively, and when the powder in the powder receiving cylinder is full, the powder is poured into the corresponding silo to realize the circulation of the powder. The powder can be pumped into the silo by pumping the powder.

[0118] Further, when the powder is added to the corresponding silo, since the silo cover is opened, the silo needs to be purged. The additive powder silo 52 and the filling powder silo 53 both include two silos, one above the other. Fig.13 As shown, the silo located above is a transition silo, and the silo located below is a powder supply silo 522, wherein an isolation valve 523 is provided between the transition silo and the powder supply silo 522, and a silo cover and an air valve are provided on the transition silo. When adding materials, the isolation valve 523 is closed, and the silo cover is opened to add powder into the transition silo. When it is full, the silo cover is closed, and air is pumped through the air valve to make the transition silo free of oxygen, and then inert gas is filled to make the atmosphere of the transition silo and the powder supply silo 522 the same. At this time, the isolation valve 523 can be opened.

[0119] Preferably, the air valve is a three-way valve, which can directly switch between the exhaust and inflation states.

[0120] Example 2 of powder circulation

[0121] Combination Figure 1 As shown, in a preferred embodiment, a powder suction pipe 501 is provided between the powder receiving cylinder and the powder bin, and a powder suction component is provided on the pipe, and the powder at the powder discharge port is sucked into the powder bin through the powder suction component.

[0122] Specifically, the first powder receiving cylinder 57 and the second powder receiving cylinder 58 are both provided with valves. After pouring and screening are completed, the valves are opened, and the first powder sucker 54 connected to the first powder receiving cylinder 57 is opened accordingly, and the second powder sucker 55 connected to the second powder receiving cylinder 58 is opened accordingly. Through the suction effect of the first powder sucker 54 and the second powder sucker 55, the corresponding powder is sucked into the corresponding powder bin.

[0123] Preferably, in order not to destroy the protective gas atmosphere in the sealed box 100, the first powder absorber 54 and the second powder absorber 55 are respectively provided with an exhaust duct 503 and a powder exhaust duct 502, wherein the powder exhaust duct 502 is connected to the corresponding powder bin, and the exhaust duct 503 is connected to the sealed box 100, so that the gas forms a circulation and the powder is also recovered.

[0124] Furthermore, in order to reduce the impact of the airflow discharged into the sealed box 100, an air uniforming box 504 is set in the sealed box 100, and the exhaust port of the air uniforming box 504 is set in a strip shape and faces the upper and lower directions of the sealed box 100 to reduce the airflow speed and avoid generating lateral airflow.

[0125] As mentioned above, by recycling the recovered powder to the powder bin, the powder can be recovered in real time for powder supply, thereby reducing the amount of additive powder used during processing.

[0126] In the above embodiment, in order to ensure that the powder does not fall onto the positioner, a guide plate 514 is provided on one side of the forming cylinder 30, the first end of the guide plate 514 is connected to the edge of the forming cylinder 30, and the second end is located above the screen 51. The excess powder on the forming cylinder 30 can be scraped onto the guide plate 514 by the scraper 61.

[0127] In a preferred embodiment, the collecting hopper 513 and the screen 51 are arranged in a pull-out form below the forming cylinder 30. When printing different workpieces, especially when different types of powders need to be replaced, the collecting hopper 513 and the screen 51 are replaced as a whole to avoid mixing and interference of the powders.

[0128] It can be understood that the powder suction pipe and powder bin used are both configured to be detachable so as to be adaptively replaced when the powder is replaced.

[0129] Powder

[0130] The powder scraping component 60 includes a powder scraping knife 61 , which is intended to scrape the additive powder on the surface of the forming cylinder 30 to form a predetermined thickness, so as to ensure the accuracy of powder spreading printing.

[0131] The scraper 61 is supplied with powder by the powder falling from the silo. Specifically, taking the powder supply silo with two silos as an example, a control valve 524 is provided at the bottom of the powder supply silo 522 for controlling the amount of powder falling out. According to demand, the amount of powder falling out at one time is sufficient to lay a layer of additive powder.

[0132] In an optional embodiment, in combination with Fig.14 As shown, the first scraper blade 61c is configured to include two blades, and a powder storage space is formed between the two blades. The amount of powder stored each time can meet the needs of one round trip scraping of powder by the third scraper blade 61c.

[0133] Specifically, when the first scraper 61c is on the left side of the molding cylinder and moves from the left side to the right side, the powder storage space between the two blades stores the amount of powder used back and forth, and the first scraper 61c scrapes the powder that falls on the powder storage space from left to right on the upper end surface 311 of the molding cylinder 30. When the first layer is laid and sintered, the first scraper 61c is on the right side of the molding cylinder, moving from right to left side to spread powder for the second time. When it reaches the left side of the molding cylinder, the powder has just been spread, and the powder supply bin 522 supplies powder again.

[0134] In this way, the additive powder is spread by the above-mentioned powder spreading method.

[0135] Furthermore, the method of spreading the filling powder may be the same as the method of spreading the additive powder.

[0136] When the amount of filling powder to be spread at one time is large, there is no need for reciprocating powder spreading. Preferably, a sufficient amount of powder can be directly dropped on the upper end surface 311 of the forming cylinder 30, and scraped into the pit formed between the substrate 32 and the cylinder body of the forming cylinder by a scraper at one time to increase the spreading speed of the filling powder.

[0137] Further, combined with Figure 2 As shown, in order to prevent the powder from spilling out of the molding cylinder, a baffle 62 is provided on the outer side of the powder scraper 61.

[0138] It can be understood that the scraper blade 61 and the baffle plate 62 are connected to a lifting mechanism (not shown in the figure). When the forming cylinder 30 is turned over, the scraper blade 61 and the baffle plate 62 are raised to avoid interfering with the movement of the forming cylinder 30.

[0139] Preferably, in order to ensure that a large amount of filling powder is filled in at one time and spread out tightly, a pressing plate 15 is provided in the sealing box 100, wherein the pressing plate 15 is driven by a robot. After the filling powder is filled, the pressing plate 15 is used to press on the surface of the filling powder to compact the powder.

[0140] [Additive processing method based on 3D powder printing]

[0141] Due to the characteristics of powder-laying printing, large-sized workpieces require more powder, and the powder utilization rate is related to the actual ratio of the workpiece volume to the molding cylinder volume. Therefore, the smaller the workpiece volume and the larger the molding cylinder size, the lower the powder utilization rate of the workpiece. Therefore, how to improve the powder utilization rate is currently a concern.

[0142] The second aspect of the present invention proposes a technical solution, an additive processing method based on 3D powder printing, including an alternating continuous process and an interruption process. In the continuous process, the printing process is divided into several layers according to the size of the workpiece, and each layer corresponds to a slice structure. The powder bin of the additive powder controls the amount of powder falling of each layer, and the powder is spread on the surface of the substrate by a scraper and sintered by a laser according to a predetermined path to form a single-layer slice structure; and each layer of the slice structure is printed layer by layer from the bottom to the top until a complete workpiece is formed;

[0143] Among them, the interruption process occurs after any layer of the slice structure is processed and formed in the continuous process. During the interruption process, the forming cylinder is flipped over to pour out the additive powder, and then the forming cylinder is restored to a horizontal position, and the powder is backfilled to the height layer before the interruption, and the interruption process ends.

[0144] Among them, additive powder is the powder that is sintered to form the product body according to product needs, and the filling powder does not participate in the process of being sintered to form the product body. Therefore, the filling powder can be made of other material powders that are heat-resistant, have good support and are low in price.

[0145] This solution divides the printing process into a continuous process and an interruption process, wherein the continuous process is the normal powder spreading and printing process, and the interruption process is the process of replacing powder, wherein the alternation of the continuous process and the interruption process is determined by the amount of powder in the additive powder bin. For example, the volume of the forming cylinder is 900L, the actual volume of the product is 200L, and there are 300L of powder in the additive powder bin. Then, every 300L of continuous powder spreading will enter the interruption process, and each interruption will recycle the additive powder in the original forming cylinder 30 into the additive powder bin. In this way, processing can be carried out when there are at least 200L of additive powder and 700L of filling powder.

[0146] Preferably, the poured additive powder is collected and supplied to the additive powder bin as printing material used in the continuous process after the interruption process, so as to save the total usage of additive powder.

[0147] Furthermore, in order to save the backfilling time of the backfilling powder, the particle size of the backfilling powder is larger than the particle size of the additive powder.

[0148] Preferably, after backfilling the filling powder, the backfilled filling powder layer is pressurized by a pressing plate to compact the backfilled filling powder layer.

[0149] Furthermore, in order to enable powder-laying additive to process suspended structures, the additive processing method based on 3D powder-laying printing also includes a bridging processing process, the bridging processing process is in an interrupted process, and the workpiece to be added is defined to include a suspended structure, wherein the suspended structure is defined as a state structure in which the lower part of the structure is not connected to the main structure, or the angle formed by the bottom contour inclination and the substrate is less than 40°, and when the bottom of the suspended structure has a support, it belongs to the main structure;

[0150] The bridging process steps include:

[0151] Step Qa, dumping the additive powder in the molding cylinder to flip the molding cylinder at a predetermined angle; it is understandable that when dumping the powder, it is not necessary to ensure that the powder is completely dumped;

[0152] Step Qb, adding material to form a support structure parallel to the substrate on the surface of the main structure at a height layer corresponding to the bottom of the suspended structure;

[0153] Step Qc, adding material to the surface of the support structure to form a suspended structure until the suspended structure is connected to the main structure;

[0154] Wherein, in step Qb, the angle between the support structure and the horizontal plane is greater than 40°.

[0155] Since laser cladding is used to add material to form the support structure, the angle between the support structure and the horizontal plane should be greater than 40° during the secondary addition based on the main structure, so as to facilitate cladding to form a support structure of a predetermined shape.

[0156] Preferably, in step Qb, the supporting structure is formed by laser cladding; and in step Qc, the suspended structure is formed by laser cladding or powder printing.

[0157] In a specific embodiment, after the support structure is additively formed, its upper end surface should be flush with the upper end surface of the main structure, so that powder can be applied and printed simultaneously for the main structure and the suspended structure.

[0158] Furthermore, since the processing of the above-mentioned support structure uses laser cladding processing, the precision of laser cladding additive is low, therefore, subtractive fine processing is also required. Therefore, the additive processing method based on 3D powder printing also includes a subtractive processing process, and the subtractive processing process is in an interrupted process. The subtractive processing process includes the following steps:

[0159] Step Ja, dumping the additive powder in the molding cylinder to flip the molding cylinder at a predetermined angle;

[0160] Step Jb: Remove the support structure through a machining center.

[0161] [Additive processing method of powder printing]

[0162] At present, the layer height of powder printing is related to the particle size of the printing material. Due to the precision requirements, the power of the laser and other conditions, the layer thickness is generally 0.02-0.1mm. For some powder printing environments with low precision requirements, the powder printing method with large particle size and large layer thickness is adopted. The processing speed is significantly improved, but the powder is not compact enough, which can easily cause defects such as cracks in the workpiece.

[0163] The third aspect of the present invention provides a technical solution, a powder-laying printing additive processing method, wherein the printing process is divided into several layers according to the size of the workpiece, the layer height H of each layer is the same, and each layer corresponds to a slice structure, the amount of powder falling of each layer is controlled by the additive powder bin, and the powder is spread on the surface of the substrate by a scraper and sintered by a laser according to a predetermined path to form a single-layer slice structure; and each layer of the slice structure is printed layer by layer from the bottom to the top until a complete workpiece is formed;

[0164] After each workpiece with a preset layer height is formed by adding materials, powder pressing is performed, and the steps of powder pressing include:

[0165] Step Ya, the substrate is lowered to a powder pressing height, the powder pressing height is greater than or equal to a layer height H, and powder is spread, and the powder spreading thickness is greater than the powder pressing height;

[0166] Step Yb, the pressing plate moves downward from above the forming cylinder to press the powder on the surface of the forming cylinder;

[0167] Step Yc: the pressing plate is reset, the substrate is raised to the powder pressing height, and the scraper scrapes off the excess powder to complete the powder pressing.

[0168] By interrupting the continuous powder spreading and pressing the powder, the compactness of the large-particle powder structure can be ensured, thereby ensuring the processing quality.

[0169] Although the present invention has been disclosed as above with preferred embodiments, it is not intended to limit the present invention. A person with ordinary knowledge in the technical field to which the present invention belongs may make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention shall be determined by the definition of the claims.

Claims

1. An additive processing device based on 3D powder printing, comprising an additive processing area surrounded by a sealed box, characterized in that: The additive processing area is provided with a carrying platform, a positioner, a molding cylinder, a powder supply system, a laser and a powder scraping component. The sealed box is filled with inert gas and is provided with an air inlet and an exhaust port. The air inlet and the exhaust port are connected to a gas circulation system, so that the additive processing area is in an inert gas protection atmosphere; The powder supply system includes an additive powder bin, which spreads powder layer by layer into the forming cylinder through a powder scraping component, and the laser sinters the additive powder according to a predetermined path to form a main structure; Also included is a subtractive machining region and a track structure, wherein a first end of the track structure extends to the additive machining region and a second end extends to the subtractive machining region; The carrying platform can move on the track structure to travel between the additive processing area and the subtractive processing area; The subtractive processing area is provided with a processing center for performing subtractive processing on the workpiece formed in the forming cylinder in the subtractive processing area; The positioner is mounted on the carrying platform, the molding cylinder is fixed to the load surface of the positioner, and can be driven by the positioner to continuously rotate around the axis Z of the molding cylinder and the Y axis perpendicular to the Z axis; The positioner includes a first support frame, a second support frame and a rotating table. The second support frame is arranged on the inner side of the first support frame and can be driven by a flipping driver to flip along the Y-axis relative to the first support frame. The rotating table is fixed to the second support frame, and the forming cylinder is connected to the upper end of the rotating table so that the forming cylinder can rotate around the axis of the forming cylinder relative to the second support frame.

2. The additive processing device based on 3D powder printing according to claim 1 is characterized in that: The second support frame is configured to be U-shaped, a mounting plate is disposed on the rotating table, and the forming cylinder is detachably connected to the mounting plate.

3. The additive processing device based on 3D powder printing according to claim 1 is characterized in that: The power supply lines of the positioner and the forming cylinder are integrated into a bundle, and the power supply connectors form a socket strip, which is pluggable and connected to the power supply socket in the sealing box.

4. The additive processing device based on 3D powder printing according to claim 1 is characterized in that: The first support frame is provided with a first power supply line, the second support frame is provided with a second power supply line, the forming cylinder is provided with a third power supply line, the first support frame and the second support frame are hinged with a first conductive slip ring, the rotating table is provided with a second conductive slip ring, the first power supply line and the second power supply line are electrically connected through the first conductive slip ring, and the second power supply line and the third power supply line are electrically connected through the second conductive slip ring, so that the positioner can continue to rotate along the Z axis and / or flip along the Y axis while still maintaining power supply with an external power supply.

5. The additive processing device based on 3D powder printing according to claim 1, characterized in that: It also includes a laser cladding component, which is configured to be driven by a robot and move around the main structure formed on the molding cylinder substrate to repair the main structure or to add material to the surface of the main structure to form a supporting structure and a suspended structure.

6. The additive processing device based on 3D powder printing according to claim 1 or 5, characterized in that: The powder supply system also includes a filling powder silo, which spreads a predetermined thickness of filling powder into the forming cylinder through a powder scraping component, the additive powder silo is provided with additive powder, and the filling powder silo is provided with filling powder, and the particle size of the filling powder is larger than that of the additive powder.

7. The additive processing device based on 3D powder printing according to claim 6, characterized in that: A powder screening component is provided on one side of the forming cylinder. When the forming cylinder is driven by the positioner to tilt, the mixed powder in the forming cylinder falls into the powder screening component and is screened into additive powder and filling powder.

8. The additive processing device based on 3D powder printing according to claim 7, characterized in that: The powder screening component includes a screen and a collecting bucket, wherein the screen is arranged at the upper part of the collecting bucket, so that powder smaller than the screen holes of the screen falls into the collecting bucket, and powder larger than the screen holes of the screen remains on the surface of the screen, wherein the screen is arranged at an angle, a first row of powder openings is provided at the lower end of the screen, and a second row of powder openings is provided at the bottom of the collecting bucket.

9. The additive processing device based on 3D powder printing according to claim 8, characterized in that: The invention also includes a first powder receiving cylinder and a second powder receiving cylinder, wherein the first powder receiving cylinder is connected to the first powder discharge port, and the second powder receiving cylinder is connected to the second powder discharge port, the first powder receiving cylinder is used to supply the additive powder bin, and the second powder receiving cylinder is used to supply the filling powder bin.

10. An additive manufacturing method based on 3D powder printing, characterized in that: The additive processing device based on 3D powder printing according to claim 1 includes an alternating continuous process and an interrupted process. In the continuous process, the printing process is divided into several layers according to the size of the workpiece, and each layer corresponds to a slice structure. The additive powder bin controls the amount of powder falling for each layer, and the powder is spread on the surface of the substrate by a scraper and sintered by a laser according to a predetermined path to form a single-layer slice structure; Each layer of slice structure is printed layer by layer from the bottom to the top until a complete workpiece is formed; Among them, the interruption process occurs after any layer of the slice structure is processed and formed in the continuous process. During the interruption process, the forming cylinder is flipped over to pour out the additive powder, and then the forming cylinder is restored to a horizontal position, and the filling powder is backfilled to the height layer before the interruption to form a filling powder layer, and the interruption process ends.

11. The additive processing method based on 3D powder printing according to claim 10, characterized in that: The poured additive powder is collected and supplied to the additive powder bin as printing material for the continued process after the interruption of the process.

12. The additive manufacturing method based on 3D powder printing according to claim 10, characterized in that: The particle size of the backfilled filling powder is larger than that of the additive powder.

13. The additive manufacturing method based on 3D powder printing according to claim 10, characterized in that: After backfilling the filling powder, the backfilled filling powder layer is pressurized by a pressing plate to compact the backfilled filling powder layer, wherein the base plate of the forming cylinder is lowered to a height greater than the workpiece addition height.

14. The additive processing method based on 3D powder printing according to claim 10, characterized in that: It also includes a bridging process, wherein the bridging process is in an interrupted process, and the workpiece to be added includes a suspended structure, wherein the suspended structure is defined as a state structure in which the lower part of the structure is not connected to the main structure, or the angle formed by the bottom contour inclination and the substrate is less than 40°, and when the bottom of the suspended structure has a support, it belongs to the main structure; The bridging process step comprises: Step Qa, dumping the additive powder in the molding cylinder to flip the molding cylinder at a predetermined angle; Step Qb, adding material to form a support structure parallel to the substrate on the surface of the main structure at a height layer corresponding to the bottom of the suspended structure; Step Qc, adding material to the surface of the support structure to form a suspended structure until the suspended structure is connected to the main structure; Wherein, in step Qb, the angle between the support structure and the horizontal plane is greater than 40°.

15. The additive manufacturing method based on 3D powder printing according to claim 14, characterized in that: In step Qb, the supporting structure is formed by laser cladding or welding; in step Qc, the suspended structure is formed by laser cladding or powder printing.

16. The additive manufacturing method based on 3D powder printing according to claim 14, characterized in that: The subtractive processing is also included, wherein the subtractive processing is in an interrupted process, and the subtractive processing comprises the following steps: Step Ja, dumping the additive powder in the molding cylinder to flip the molding cylinder at a predetermined angle; Step Jb: Remove the support structure through a machining center.

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