Laser sintering machine

Abstract

A laser manipulation machine (100) for laser sintering for producing a three-dimensional object starting from a digital 3D model by sintering layers using a laser source and optics, mechanical means for depositing a powder bed on a working surface, and a mechanical system for removing fumes and / or contaminants resulting from the selective powder melting process as close as possible to the melted layer or layers before they diffuse inside the working chamber, and for introducing process gases necessary for the treatment of the powder bed melting in a localized manner in the vicinity of the layer or layers undergoing the selective melting process into the same chamber.

Description

Technical Field

[0001] The present invention relates to a laser working machine for laser sintering as described in the preamble of claim 1. In particular, an innovative sintering system for powder bed melting technology or additive manufacturing using a bed of metal powder and / or resin and / or polymer material will be described.

Background Art

[0002] Additive manufacturing (AM) is a series of additive manufacturing powder processes that start from a computerized 3D model of a specific object and produce an object starting from a digital model, in contrast to conventional subtractive techniques such as chip removal, cutting, and drilling machining that start from a material block where chips are mechanically removed. It is possible to perform subdivision into multiple layers in order to obtain a scheme of layers of results processed by a machine tool for sintering or vapor deposition processes of various types of materials such as metal, plastic, resin, polymer, composite components, etc., using software integrated into the machine's control system or an online service.

[0003] The main feature of this technology is that it is a production process capable of producing parts with a shape very close to the shape of the final part according to the requirements of the project drawing. Among the AM family, there are selective melting / sintering of powder beds of materials such as metal, plastic, resin, polymer, and composite components using a laser beam (selective laser beam melting - SLBM, or selective laser beam sintering - SLBS) (or powder bed melting or PBF, binder jet casting, fused filament fabrication, stereolithography (also known as SLA), where the interaction with an energy source occurs after powder of materials such as metal, plastic resin, polymer, composite components, etc. is deposited on a structural support), laser beam deposition of metal by a laser beam (laser beam metal deposition - LBMD), where powder is sprayed onto a support using one or more nozzles and simultaneously irradiated with an energy beam, and selective electron beam melting (SEB M), etc., and several technologies with different characteristics can be identified.

[0004] In powder bed fabrication (PBF) technology for materials such as metals, plastics, resins, polymers, and composites, a laser beam using a lens system and scanner is used as a high-power-density heat source necessary to melt the powder of these materials only in specific, predetermined areas where densely packed material needs to be obtained for the fabrication of three-dimensional parts. Specifically, the powder contained in a special hopper is fed onto the build surface using a feeding system and spread through a doctor blade into layers typically of 20-60 μm, after which the laser beam is selectively irradiated according to the desired shape. The advantage associated with the use of a laser beam is that the high power density, which leads to rapid melting of the powder, can be focused on small dimensions, usually in the range of 30 μm to 180 μm in diameter, thus ensuring a good level of precision with respect to the surface finish of the manufactured parts. A substrate with a powder bed that is not hit by the laser beam provides mechanical support to the part being fabricated, and in fact, after the first layer is completed, the platform is lowered and new powder is spread, and the already deposited layers should not be moved. The build plate also plays a crucial role in dissipating the heat generated during the process, and in some cases, it can be heated to reduce the temperature gradient between the build plate and the part being built, which could lead to high voltage, residue, and the resulting deformation of the part. To maximize the use of the work area, it is also possible to build multiple parts in the same powder bed. Typically, powder bed processes are carried out in a chamber that is infused with an inert gas to prevent oxidation of the material. These features have made powder bed technology accessible to the powder market for manufacturing parts in a wide range of fields, from aerospace to medical, from automotive to jewelry. In particular, the high flexibility of powder bed technology compared to conventional manufacturing techniques makes it possible to achieve a very high level of part customization.

[0005] The powder bed or PBF process is characterized by various factors that determine the final properties of the manufactured part in terms of density, microstructure, and mechanical properties, particularly the interaction between radiation and matter, the material's absorption properties of electromagnetic radiation energy, and the temperature of the powder bed. The material's absorption properties include parameters such as density, thermal conductivity, specific heat, and emissivity, which change with the temperature of the material itself and determine the processing process of the material in additive manufacturing techniques in powder bed or powder bed fusion.

[0006] The selection of process parameters such as laser power, laser scanning speed on the powder bed, laser beam shape, and materials used affects the structural and surface quality of the manufactured parts, as well as the productivity of the system. This is crucial for the use of this type of machine in the powder field, especially in areas covered today by casting and / or hot molding and / or die casting, as it also offers advantages such as high spatial resolution, capillary process control, and the ability to perform powder bed pretreatment and post-treatment of newly molten material.

[0007] The laser-based melting process takes place inside a working chamber under an inert gas atmosphere (e.g., nitrogen, argon, etc.), which contains several handling devices that allow for control of powder addition. This ensures the realization of parts, the removal of fumes generated from the selective melting process, and the introduction of support gases into the production process.

[0008] Many systems for sintering metal powder using additive manufacturing technology are known in the art, for example, Patent Document 1 relating to an additive manufacturing system having a laser matrix, each generating an energy beam to form a powder bed melting chamber; Patent Document 2 describing an additive manufacturing system comprising a device having a powder bed and a series of laser emitters, and including a manifold configured to melt at least a portion of the powder bed as it moves toward the powder bed and to suck up fumes; and Patent Document 3 relating to a gas introduction and suction system from a work area, comprising inlet and outlet nozzles arranged to create a gas flow that passes at least partially over the work area and the joining area.

[0009] The main drawbacks of the conventional technology are that the sintering system has multiple optical systems fixed above the work surface that are necessary for transporting electromagnetic radiation and cannot move along the powder bed, and that the extraction of process fumes and the input of support gases are not localized but limited to the boundary walls of the work chamber, and not localized near the process performed on one or more layers of powder by the laser used, which limits the introduction of complex alignment processes on the optical components on the work surface, and that defects and / or inclusions are formed in the molten material, and therefore small and / or large defects and / or inclusions are formed in the final part. Furthermore, these are devices that do not have a refractory system to contain the gases necessary for the sintering process using additive manufacturing technology. [Prior art documents] [Patent Documents]

[0010] [Patent Document 1] International Publication No. 2018 / 151911 [Patent Document 2] International Publication No. 2018 / 156254 [Patent Document 3] European Patent No. 3050648 [Overview of the project] [Problems that the invention aims to solve]

[0011] The object of the present invention is to solve the aforementioned prior art problems using a laser sintering machine (100) through a mechanical and technical solution comprising a simple optical system designed to transmit and focus a beam of electromagnetic radiation emitted by a laser in a predetermined area of ​​the work surface without requiring complex alignment procedures. Another object is to provide a mechanical solution that utilizes a system integrated with the optical system to locally remove process fumes from the worktop and introduce process auxiliary gases into the powder bed. Yet another object is the use of a refractory system to contain the gases required for a sintering process using additive manufacturing technology. [Means for solving the problem]

[0012] The above and other objects and advantages of the present invention are achieved by a laser sintering machine such as the one described in claim 1, as will become apparent from the following description. Preferred embodiments and non-obvious modifications of the present invention form the subject matter of the dependent claims.

[0013] It is understood that all of the attached claims form an integral part of this description.

[0014] As is evident from the attached claims, it will be immediately apparent that countless changes and modifications can be made to the described content (for example, relating to shape, dimensions, arrangement, and parts having equivalent functionality) without departing from the scope of the present invention.

[0015] The present invention will be further described in detail by several preferred embodiments provided as non-limiting examples with reference to the accompanying drawings. [Brief explanation of the drawing]

[0016] [Figure 1]The laser sintering machine (100) according to the present invention is shown. [Figure 2] The optical system (101) and gas suction / introduction system (106) according to the present invention are shown. [Figure 3] The terminal section of the optical system (101) and gas suction / introduction system (106) according to the present invention is shown. [Figure 4] The mode of the electromagnetic radiation beam (120) according to the present invention is shown. [Figure 5] This shows a front view of the ring nut (500) of the optical system (101) and gas suction / introduction system (106) according to the present invention. [Modes for carrying out the invention]

[0017] The laser machine (100) for laser sintering for additive manufacturing, as can be seen in Figure 1, is designed to produce three-dimensional objects starting from a digital 3D model by sintering layers using a laser light source and optics and mechanical means suitable for depositing a powder bed of materials such as metals, plastics, resins, polymers, and composites onto a work surface, utilizing a laser (102) laser (102) to emit a beam of electromagnetic radiation (120) onto a predetermined area of ​​the work surface (130) The system comprises an optical system (101) designed to transmit and focus light into a region, the optical system being connected to the upper part of a laser work machine (100), a work surface (130) designed to accommodate a powder bed of materials such as metals, plastics, resins, polymers, and composite components (131), and operably connected to a piston (170), a system (106) for fume extraction and support gas introduction designed to locally remove process fumes from the work surface (130) and to introduce process support gases into the powder bed of materials such as metals, plastics, resins, polymers, and composite components (131), the system (106) being operably connected to the optical system (101) and a gas container unit (230) designed to accommodate a process gas cylinder that is fireproof and operably connected to the laser work machine (100).

[0018] The laser working machine (100) for laser sintering is equipped with an optical system (101) that can be moved along the X, Y, and Z axes within the periphery of the working surface (130) by a mechanical and / or magnetic drive device (113). The optical system (101) does not require complex alignment procedures. In one or more embodiments, the optical system (101) is at least one optical component that can collect the beam (120) of electromagnetic radiation on the working surface (130) by reflection and / or refraction of the beam (120) of electromagnetic radiation. A plate required for dissipating the generated heat is accommodated during the casting process. The plate can be heated to reduce the thermal gradient of the component being shaped, which may lead to the formation of high residual stresses and subsequent deformation of the component. The optical component can be composed of at least one optical component that can collimate the beam of electromagnetic radiation by at least one optical component that can also be reflective and / or transmissive for the additive manufacturing process and additive manufacturing applications.

[0019] Advantageously, as can be seen from Figure 1, the optical system (101) comprises one or more reflective and / or transmissive fixed and / or movable optical elements (160) necessary to change the position along the Z-axis of a spot of an electromagnetic radiation beam (120) for focusing the electromagnetic radiation beam, which is emitted by a laser (102) having a wavelength in the range of 180 nm to 11000 nm in output from a central region (202) of a cylindrical and / or conical nozzle (200) connected to a ring nut (500) in a predetermined area of ​​the work surface (130), and the diameter and shape of the laser beam (top hat (402), donut (403), or vessel (404)), and for performing the additive manufacturing process. The focal spot of a laser beam refers to the minimum diameter on the focal plane when the beam is focused by a reflective and / or transmissive optical component in caustic space, which represents a set of curves modeling the propagation of a ray emitted from a parallelized laser source. This diameter or spot is the region around the propagation axis of the laser beam where most of the power of the laser source is concentrated. As can be seen from Figures 4a, 4b, 4c, and 4d, the laser beam can be of the Gaussian type (401), where the intensity profile on a plane perpendicular to the propagation direction follows a Gaussian distribution and the energy distribution is concentrated in the center and decreases towards the tail; a top-type hat (402), where the intensity profile is nearly flat and the energy distribution is more concentrated in the center and tends to be zero along the edges; a donut type (403) or a donut type due to its characteristic shape, where the energy distribution is concentrated by a ring surrounding its shape, has a minimum point in the center and tends to decrease towards the tail; and a Bessel (404), where the amplitude is described by a first type of Bessel function and neither diffracts nor diffuses during propagation.

[0020] As shown in FIG. 1, the laser working machine (100) for laser sintering can be provided with a laser light source (102) integrally connected to the upper part of the optical system (101), or the laser light source (102) does not necessarily have to be arranged above the optical system (101). Further, the laser working machine (100) for laser sintering is provided with a doctor blade or recoater (103) operably connected to the working surface (130) by moving means such as an actuator and / or a sliding track. The doctor blade or recoater (103) is designed to spread a layer of metal powder and / or resin and / or polymer material (131) on the working surface (130) for additive manufacturing applications.

[0021] Advantageously, as can be seen from FIGS. 1 and 2, the system (106) for fume suction and support gas introduction is operably connected to the optical system (101) and is designed to translate in the X, Y, and Z directions of the working surface (130). The system (106) for fume suction and support gas introduction can locally introduce the gases required for the process onto the bed of the metal powder and / or resin and / or polymer material (131) on the working surface (130) and locally suck the process fumes from the bed of the metal powder and / or resin and / or polymer material (131) on the working surface (130) of the machine tool (100).

[0022] The system (106) for fume suction and support gas introduction is designed to transmit the suction of process fumes through at least two channels (203) and (204) connected to a nozzle (200), preferably concentric with a suction unit (140) by a ring nut (500) containing the nozzle (200) and at least one duct (145) and duct (146). The system (106) for fume suction and support gas introduction is provided with a pump (141) necessary for locally suctioning fumes generated from the process within a work surface (130), the pump (141) being connected to the suction unit (140) and a filtration unit (220) by ducts (145) and (146). Furthermore, a circular, or for example, square and / or conical ring nut (500), connected to the end of the nozzle (200) of the system (106) for suction of fumes and introduction of support gases, consists of an external ring (506) with a set of circular and / or square and / or rectangular outlets (501) suitable for suctioning process fumes from the work area (130).

[0023] Furthermore, the system (106) for fume suction and support gas introduction is designed to transmit gas introduction through at least two channels (205) and (206) connected to a nozzle (200), preferably at least two channels (205) and (206) concentric with the nozzle (200) in a ring nut (500) and concentric with a supply unit (150) by at least one duct (155) and duct (156), and the system (106) for fume suction and support gas introduction is provided with a solenoid valve (151) necessary for locally supplying the support gas to the process on the work surface (130), the solenoid valve (151) is connected to the supply unit (150) by ducts (155) and (156) and a container gas unit (230). Furthermore, a substantially circular ring nut (500) connected to the end of the nozzle (200) of the system (106) for suctioning fumes and introducing support gases consists of an intermediate ring (507) with a set of circular and / or square and / or rectangular nozzles (502) suitable for extracting process fumes from the work area (130).

[0024] The system (106) for fume suction and support gas introduction is equipped with an air treatment unit (221), which is a device for treating air in a closed environment necessary for the purification and filtration of fumes generated from the additive manufacturing process and for air recirculation, and the air treatment unit (221) is connected to a filtration unit (220). Furthermore, the system (106) for fume suction and support gas introduction is provided with a sensor (109) for controlling the flow of aspirated particles and a sensor (110) for controlling the flow of distributed particles, and the sensors (109) and (110) are operably connected to a pump (141), a solenoid valve (151), and a control unit (108) in the machine tool (100).

[0025] Advantageously, the ring nut (500) connected to the end of the nozzle (200) is designed to house a set of fixed and / or removable energy sources (503) necessary for heating operations before and / or after the start of the metal powder melting process in the work area (130), as shown in Figure 5, and, in the case of polymers, plastics, and / or resin-based materials, an inner ring (508) is also housed, which also houses a set of fixed and / or removable energy sources (504) necessary for photopolymerization operations of resin materials and / or polymer materials in the work area (130).

[0026] The laser sintering laser work machine (100) includes a gas container unit (230) designed to allow connection and removal of a process gas container (231), the container (231) being connected to a valve (232) by manual locking or quick coupling, the gas container unit (230) being fire-resistant, i.e., non-flammable, and furthermore, the gas container unit (230) is equipped with a sensor (111) for controlling the pressure of the process gas container (231) necessary for the insertion and removal of the process gas container (231), the sensor (111) being operably connected to the valve (232) and control unit (108).

[0027] Advantageously, the laser sintering laser work machine (100) is equipped with a temperature sensor (105) located inside the working volume (104) necessary for controlling the degree of heat within the working volume (104), and at least one optical sensor (107) necessary for checking the precise spread of the metal powder and / or resin and / or polymer material (131) on the floor, the temperature sensor (105) and the optical sensor (107) being operably connected to the wall of the machine tool (100) and the control unit (108), and further, a sensor (112) is also located inside the working volume (104) necessary for controlling the pressure within the working volume (104), the sensor (104) being operably connected to the wall of the machine tool (100) and the control unit (108).

[0028] The laser sintering laser work machine (100) is designed to fabricate three-dimensional objects using powder bed fusion or powder bed fusion technology, and the following steps: A powder diffusion step in which a doctor blade or recoater (103) spreads metal powder and / or resin and / or polymer material (131) onto a work surface (130), A laser sintering step in which a laser (102) uses a set of optical elements (160) to radiate a beam of electromagnetic radiation (120) onto a floor of metal powder and / or resin and / or polymer material (131) in a work surface (130), A system (106) for fume suction and support gas introduction, integrated with an optical system (101), suctions fumes generated from the laser sintering process from the metal powder and / or resin and / or polymer material (131) floor of the work surface (130), and introduces the gases necessary for the laser sintering process into the powder floor (131) of the work surface (130), comprising a suction and gas injection step, Includes.

[0029] Furthermore, the optical system (101) can move along the X, Y, and Z axes within the periphery of the work plane (130) for additive manufacturing applications, and in particular the optical system (101) Mechanical or optical movement along the Z-axis to position the optical element (160) above the focal point for mechanical support applications. The position of the optical element (160) in focus for processing along the contour of one or more layers to be fabricated by mechanical or optical movement along the Z-axis, and The position below the focal point of the optical element (160) for processing within one or more layers to be fabricated by mechanical or optical movement along the Z-axis, Processing can be performed using this method.

[0030] Furthermore, the powder diffusion step, laser sintering step, and gas suction / injection step are performed within a working volume (104) in an inert or vacuum atmosphere.

Claims

1. A laser sintering laser work machine (100) comprising an optical system (101), a work surface (130), a gas container unit (230), and a system (106) for suction of fumes and introduction of support gas, The optical system (101) is designed to transmit and focus the beam of electromagnetic radiation (120) emitted by the laser light source (102) to a predetermined area of ​​the work surface (130), and the optical system (101) is connected to the upper surface of the laser work machine (100). The work surface (130) is designed to accommodate a floor of metal powder and / or resin and / or polymer material (131) and is operably connected to a piston (170). The gas container unit (230) is designed to house a process gas cylinder, is fire-resistant, and is operably connected to the laser work machine (100). The system (106) for suctioning the fume and introducing support gases is designed to locally remove process fumes from the work surface (130) and introduce process support gases to the floor of the metal powder and / or resin and / or polymer material (131), and is operably connected to the optical system (101). The fume suction and support gas introduction system (106) is designed to locally introduce process-necessary gases in the metal powder and / or resin and / or polymer material (131) floor within the work surface (130) of the machine tool (100), and to locally suction process fumes from the metal powder and / or resin and / or polymer (131) floor within the work surface (130) of the machine tool (100), the fume suction and support gas introduction system (106) transmits the suction of process fumes through at least two channels (203 and 204), and the at least two channels (20 Laser sintering laser work machine (100), characterized in that 3 and 204) are concentric and connected to a nozzle (200), the nozzle (200) is connected to a ring nut (500) having an inner ring (508) in which a set of fixed and / or removable energy sources (503) necessary for heating metal powder and / or photopolymerization of resin and / or polymer materials in a work area (130), and a system (106) for suction of fumes and introduction of support gases is connected to a suction unit (140) by at least one duct (145) and one duct (146).

2. The laser sintering laser machine (100) according to claim 1, wherein the optical system (101) is designed to move along the X, Y, and Z axes within the periphery of the work surface (130) for additive manufacturing applications within the laser machine (100), and the optical system (101) is comprised of one or more fixed and / or movable reflective and / or transmissive optical elements (160) necessary to perform an additive manufacturing process by focusing the beam of electromagnetic radiation (120) emitted from the central region (202) of a cylindrical and / or conical nozzle (200) connected to a ring nut (500) in a predetermined area of ​​the work surface (130).

3. The laser sintering laser work machine (100) according to claim 1, characterized in that the optical system (101) is provided with at least one laser light source (102) which is integrated or non-integrated and connected to the optical system (101).

4. A laser sintering laser work machine (100) according to claim 1, characterized in that a doctor blade or recoater (103) is designed to spread the metal powder and / or resin and / or polymer material (131) onto the work surface (130) for additive manufacturing purposes, and the doctor blade or recoater (103) is operably connected to the work surface (130) of the machine tool (100).

5. The laser sintering laser work machine (100) according to claim 1, characterized in that the system (106) for suctioning the fume and introducing the support gas is designed to translate in the X, Y, and Z directions of the planar work system (130), and the system (106) for suctioning the fume and introducing the support gas is operably connected to the optical system (101).

6. The laser sintering machine (100) according to claim 1, characterized in that the system (106) for aspirating the fume and introducing a support gas is connected at the end of the nozzle (200) to a circular ring nut (500), the ring nut (500) comprising an outer ring (506) having a set of outlets (501) suitable for aspirating process fumes from the work area (130).

7. The laser sintering laser work machine (100) according to claim 1, wherein the system (106) for aspirating the fume and introducing a support gas is provided with a pump (141) necessary for locally aspirating the fume generated from the process at the work surface (130), the pump (141) being connected to the suction unit (140) and the filtration unit (220) by the ducts (145) and (146).

8. The laser sintering laser work machine (100) according to claim 1, characterized in that the system (106) for aspirating the fume and introducing the support gas transmits the introduction of the gas through at least two passages (205) and (206), the at least two passages (205) and (206) are connected to the nozzle (200) and concentric with the nozzle (200) in the ring nut (500), and are connected to the supply unit (150) by at least one duct (155) and one duct (156).

9. The laser sintering laser work machine (100) according to claim 1, characterized in that the system (106) for aspirating the fume and introducing a support gas is indicated at the end of the nozzle (200) by a circular ring nut (500), the ring nut (500) being composed of an intermediate ring (507) having a set of outlets (502) suitable for introducing a process gas into the work area (130).

10. The laser sintering laser work machine (100) according to claim 1, wherein the system (106) for suctioning the fume and introducing the support gas comprises a solenoid valve (151) necessary for locally supplying the process support gas to the work surface (130), and the solenoid valve (151) is connected to a supply unit (150) and a gas container unit (230) by ducts (155) and (156).

11. The laser sintering laser work machine (100) according to claim 1, characterized in that the system (106) for suctioning fumes and introducing support gases comprises an air treatment unit (221) necessary for purifying and filtering fumes generated from the additive manufacturing process and for recirculating air, the air treatment unit (221) being connected to a filtration unit (220).

12. The laser sintering laser work machine (100) according to claim 1, wherein the system (106) for aspirating the fume and introducing a support gas comprises a sensor (109) capable of measuring the contents of the aspirated particle flow and a sensor (110) capable of measuring the contents of the supplied particle flow, and the sensors (109) and (110) are operably connected to a pump (141), a solenoid valve (151), and a control unit (108) in the machine tool (100).

13. The laser sintering laser work machine (100) according to claim 1, characterized in that a gas container unit (230) is designed to allow connection and removal of a process gas container (231), the container (231) is connected to a quick coupling valve (232), and the gas container unit (230) is fire-resistant.

14. The laser sintering laser work machine (100) according to claim 1, wherein the gas container unit (230) is provided with a sensor (111) for controlling the pressure of the gas process container (231) necessary for inserting and removing the process gas container (231), and the sensor (111) is operably connected to a valve (232) and a control unit (108).

15. A laser sintering method by an additive manufacturing process, wherein the laser sintering method is A powder diffusion step in which a floor of metal powder and / or resin and / or polymer material (131) is spread onto a work surface (130) using a doctor blade or recoater (103), The steps include heating metal powder in a work area (130) and / or photopolymerizing a resin material and / or polymer material using a fixed and / or removable set of energy sources (503) located in the inner ring (508) of a ring nut (500), A laser sintering step in which a beam of electromagnetic radiation (120) is emitted from a laser light source (102) using a set of optical elements (160) onto the floor of the metal powder and / or resin and / or polymer material (131) in the work surface (130), A system (106) for fume suction and support gas introduction, integrated with the optical system (101), suctions fumes generated by the laser sintering process from the metal powder and / or resin and / or polymer material (131) floor of the work surface (130), and introduces the gas necessary for the laser sintering process to the metal powder and / or resin and / or polymer material (131) floor of the work surface (130), comprising a suction and gas injection step. A laser sintering method, including the following:

16. The optical system (101) can move along the X, Y, and Z axes within the periphery of the work plane (130) for additive manufacturing purposes, and in particular the optical system (101) By mechanical or optical movement along the Z-axis, the position of the optical element (160) for mechanical support purposes is above the focal point. The position within the focal point of the optical element (160) for processing along the contour of one or more layers to be fabricated by mechanical or optical movement along the Z-axis, The position below the focal point of the optical element (160) for processing within one or more layers produced by mechanical or optical movement along the Z-axis. The laser sintering method according to claim 15, wherein processing can be performed.

17. The laser sintering method according to claim 15 or 16, wherein the powder diffusion step, the laser sintering step, and the suction and gas injection step are performed in a working volume (104) in an inert or vacuum atmosphere.

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