Device for the additive manufacturing of a three-dimensional body in a powder bed

Abstract

Device for the additive manufacturing of a three-dimensional body (5) in a powder bed with a manufacturing area (1) which has a lowerable surface (2) on which the powder bed is arranged, and at least one squeegee (3) for conveying and uniformly distributing a powdered material on the surface (2), which is movable about a rotational axis (4) that is oriented perpendicular to the surface (2) of the powder bed, and a device (8) for performing a rotational movement of the at least one doctor blade (3) over the surface of the powder bed, and a device with which at least one energy beam is directed onto the surface of the powder bed and whose focal spot is movable in two dimensions, the length of the squeegee (3) corresponds at least to the greatest distance from the axis of rotation (4) to the edge of the manufacturing area (1), nozzles are formed on the squeegee (3) for applying the powdered material to the surface of the powder bed, and a device (7) for feeding powdered material into the at least one doctor blade (3) and to the nozzles is provided, characterized by the fact that the device (8) for carrying out this rotational movement is arranged such that the rotational movement takes place from the edge of the production area (1) and for this purpose, in the case of a production area (1) with a circular base area, a guide is arranged circumferentially on the outer edge of the production area (1) and above the surface of the powder bed and the at least one doctor blade (3) is arranged such that it is slidably mounted on two opposite points of the guide.

Description

[0001] The invention relates to a device for the additive manufacturing of a three-dimensional body in a powder bed.

[0002] In additive manufacturing processes using a powder bed, such as selective laser melting (SLM) or electron beam melting (EBM), a powdered material is applied to a platform in a production area using a doctor blade or nozzles and then evenly distributed across the platform with a wiper. The powder bed is then irradiated with an energy beam along a predefined geometry, melting or sintering the irradiated areas. Before each new layer is applied, the platform is lowered by the thickness of the layer. Further layers of the powdered material are applied and irradiated with at least one energy beam along a predefined geometry until the desired three-dimensional object is formed.

[0003] The process speed of such methods, carried out with known devices, depends primarily on the powder application and the irradiation of the powder bed surface. Irradiation of the powder bed surface can only occur once the powder application for the respective layer is complete. This makes the process relatively slow.

[0004] Another disadvantage of known devices is that when using different powdered materials to achieve specific properties in the three-dimensional object being produced, the powder feeder has to be emptied and then refilled in a time-consuming process before the doctor blade can be used with a different material. This further reduces the already low working speed and productivity.

[0005] DE 10 2010 041 284 A1 relates to a process for selective laser sintering and a suitable system with a rotating squeegee and a dosing device.

[0006] A method and a device for testing the additive manufacturing of a component is known from DE 2011 008 774 A1.

[0007] An arrangement for applying a powder with several doctor blades on a multi-head is disclosed in DE 10 2013 209 963 A1.

[0008] The disclosure of DE 10 2013 206 458 A1 relates to a rotary coating machine.

[0009] From DE 102 35 434 A1 a device and a method for producing a three-dimensional object using an additive manufacturing process are known.

[0010] Information on a device and a method for manufacturing, repairing and / or replacing a component using an energy radiation solidifiable powder can be found in DE 10 2010 034 311 A1.

[0011] It is therefore an object of the invention to propose a device with which three-dimensional bodies can be produced using additive manufacturing in a powder bed with a higher working speed and productivity.

[0012] The problem is solved according to the invention with a device having the features of claim 1. Advantageous embodiments are described in the dependent claims.

[0013] A device for the additive manufacturing of a three-dimensional body in a powder bed has a manufacturing area with a retractable surface. A powder bed is arranged on the retractable surface. Before each new layer of powdered material is applied, the retractable surface is lowered by a preset layer thickness, which typically corresponds to the thickness of the previously formed layer.

[0014] Furthermore, the device has at least one squeegee for conveying a powdered material onto the lowerable surface of the production area, with which the powdered material is also evenly distributed over the surface.

[0015] The at least one doctor blade is movable about an axis of rotation oriented perpendicular to the surface of the powder bed. The length of the doctor blade is at least equal to the longest distance between the axis of rotation and the edge of the production area, such that the at least one doctor blade, during its rotational movement about the axis of rotation, sweeps over every point on the surface of the powder bed. The rotating movement of the at least one doctor blade across the surface of the powder bed evenly distributes the applied powdered material and pushes excess powdered material off the surface of the powder bed.

[0016] Nozzles are arranged on at least one squeegee, by means of which the powdered material is applied to the surface of the powder bed.

[0017] Furthermore, the device includes a mechanism for feeding powdered material to the at least one doctor blade and the nozzles, as well as a mechanism for performing the rotational movement of the at least one doctor blade across the surface of the powder bed. The mechanism for performing the rotational movement can be an electrically, pneumatically, or hydraulically operated drive.

[0018] The device also includes a mechanism for directing at least one energy beam onto the surface of the powder bed, and for moving the focal spot two-dimensionally across the surface of the powder bed. The energy beam melts or sinters the powdered material along a predefinable geometry.

[0019] The surface area for applying the powdered material can have any geometric shape. Preferably, it is round, square, or rectangular.

[0020] The at least one energy beam can be a laser beam or an electron beam. The control of the at least one energy beam should be such that the at least one energy beam does not strike the at least one squeegee. According to the invention, the area in the direction of rotation behind the at least one squeegee is irradiated with the at least one energy beam without interrupting the rotational movement of the squeegee.

[0021] The at least one doctor blade can incorporate a mechanical material feed, in particular a screw conveyor, and / or a pneumatic feed for the powdered material to the nozzles of the at least one doctor blade. Alternatively, the powder can be conveyed by peristaltic deformation of the feed line.

[0022] The nozzles should advantageously discharge less powdered material onto the surface of the powder bed in the area near the axis of rotation than in the areas near the edges. This can be achieved, for example, by increasing the distance between the nozzles while maintaining at least one doctor blade in the area of ​​the axis of rotation.

[0023] Several doctor blades can be positioned above the surface of the production area. These blades can be fed with various powdered materials and / or powdered materials with different average particle size ranges, which then apply the powder to the surface of the powder bed. This eliminates the need for time-consuming cleaning of the blades when changing the material being applied.

[0024] The doctor blade can have at least one set of arms extending from the axis of rotation. This design allows for the application of a powdered material to different areas of the powder bed simultaneously, thus increasing the working speed. Different powdered materials can also be fed to the arms of a single doctor blade.

[0025] The axis of rotation for the movement of the at least one squeegee can be arranged off-center, so that three-dimensional bodies without a cavity in the area of ​​the axis of rotation can also be formed.

[0026] The rotational movement of the at least one doctor blade can be initiated from the axis of rotation by the device for executing this rotational movement. According to the invention, the device for executing this rotational movement is configured such that the rotational movement originates from the edge of the production area. For this purpose, in a production area with a circular base, a guide, such as a rail, is arranged circumferentially on the outer edge of the production area and above the surface of the powder bed. The at least one doctor blade is arranged such that it is slidably mounted on two opposite points of the guide, so that when performing a rotational movement, it sweeps over every point of the surface of the powder bed. The device for executing the rotational movement of the at least one doctor blade can move the at least one doctor blade along the guide at at least one of the support points.Alternatively, the squeegee can be firmly connected to the guide at the end faces of the squeegee, and to achieve a rotational movement, the guide, together with at least one attached squeegee, can be rotated over the production area by a stationary device for performing the rotational movement.

[0027] Additional functional elements can be arranged that rotate around the axis of rotation. For example, a device for locally preheating the powdered material, preferably by means of infrared radiation or induction, can be arranged. By locally preheating the powder bed, the melting or sintering of the powdered material by irradiation with the energy beam can be achieved more quickly.

[0028] Alternatively or simultaneously, a scraper can be arranged to rotate around the axis of rotation, so that it follows the at least one doctor blade and smooths the applied powdered material. The resulting flat surface allows for higher manufacturing accuracy.

[0029] The production area can be divided into several work zones, in which three-dimensional objects can be manufactured simultaneously. This allows for the production of a greater number of three-dimensional objects in a shorter time. It is particularly advantageous to use multiple energy beams to irradiate the powdered material. This further increases the processing speed and productivity.

[0030] With a device according to the invention, a continuous application of material to the surface of a powder bed can be carried out. In the direction of rotation, immediately after the at least one doctor blade, the surface of the powder bed can be irradiated with at least one energy beam, and a further layer of powdered material can be applied. Interrupting or completing a single process step to carry out the next is not necessary; that is, the powder application does not have to be interrupted for the irradiation of the material, and vice versa.

[0031] By designing the device with multiple squeegees or squeegee arms, the powdered material can be changed layer by layer or within a single layer, so that the material properties of the body to be manufactured can be specifically influenced.

[0032] The device will be explained in more detail below using examples.

[0033] This shows: Fig. 1 an exemplary embodiment of a device according to the invention in a perspective view, and Fig. 2 Another exemplary embodiment with a body to be manufactured in a top view.

[0034] In Fig. Figure 1 shows a manufacturing area 1 with a retractable surface 2. The base area of ​​the manufacturing area 1 and the retractable surface 2 is rectangular. A powder bed of powdered material is applied to the retractable surface 2.

[0035] The axis of rotation 4 is located centrally on and perpendicular to the surface 2, around which a doctor blade 3 rotates in the direction of arrow 6. The length of the doctor blade 3 corresponds to the distance from the axis of rotation 4 to the corners of the production area 1, so that every point on the surface of the powder bed is covered.

[0036] The doctor blade 3 is equipped with nozzles for applying a powdered material to the surface of the powder bed. Powdered material is fed to the doctor blade 3 via a feed device 7 and conveyed to the nozzles by a screw conveyor integrated into the doctor blade 3. To ensure a uniform layer thickness, less powdered material is applied to the surface of the powder bed in the area near the axis of rotation 4 than in the outer regions of the production area 1. This is achieved by spacing the nozzles further apart near the axis of rotation 4 than at the outer edge of the doctor blade 3. The doctor blade 3 is also designed to distribute the material evenly when applied to the surface of the powder bed.

[0037] An electrically operated drive is arranged as a device 8 on the axis of rotation 4 to perform a rotational movement and rotates the squeegee 3 around the axis of rotation 4.

[0038] In the direction of rotation 6 after the doctor blade, a device is used to direct a laser or electron beam onto the surface of the powder bed and to move its focal spot two-dimensionally (not shown in the figure). This device irradiates the material by deflecting the laser or electron beam two-dimensionally along a predefined geometry, causing it to melt or sinter in the irradiated area. The laser or electron beam is guided in such a way that it does not strike the doctor blade 3.

[0039] With the application of further layers, the lowerable surface 2 is lowered by the thickness of the previously applied powder layer.

[0040] In Fig. Figure 2 shows a further embodiment of a device according to the invention in a top view. A powder bed of a powdered material is applied to a production area 1 with a circular base and a retractable surface 2. The material is fed to the doctor blade 3 by means of a device 7 for feeding the powdered material to the doctor blade 3. The doctor blade 3 has a pneumatic feed for conveying the material to the nozzles formed in the doctor blade 3. The length of the doctor blade 3 is greater than the radius of the production area. The doctor blade is used as in the example. Fig. 1 is rotated by an electrically driven drive around the rotation axis 4 to apply and distribute the powdered material evenly as a layer on the surface of the powder bed.

[0041] In the direction of rotation 6 after the doctor blade, the powdered material is irradiated with a laser or electron beam, causing it to melt or sinter. By applying further layers and irradiating them along a predefined geometry, whereby the retractable surface is lowered by the thickness of one layer after each layer, the three-dimensional body 5 is formed.

Claims

[1] Device for the additive manufacturing of a three-dimensional body (5) in a powder bed with a manufacturing area (1) which has a lowerable surface (2) on which the powder bed is arranged, and at least one squeegee (3) for conveying and uniformly distributing a powdered material on the surface (2), which is movable about a rotational axis (4) that is oriented perpendicular to the surface (2) of the powder bed, and a device (8) for performing a rotational movement of the at least one doctor blade (3) over the surface of the powder bed, and a device with which at least one energy beam is directed onto the surface of the powder bed and whose focal spot is movable in two dimensions, the length of the squeegee (3) corresponds at least to the greatest distance from the axis of rotation (4) to the edge of the manufacturing area (1), nozzles are formed on the squeegee (3) for applying the powdered material to the surface of the powder bed, and a device (7) for feeding powdered material into the at least one doctor blade (3) and to the nozzles is provided, characterized by , that The device (8) for carrying out this rotational movement is arranged such that the rotational movement takes place from the edge of the production area (1) and, for a production area (1) with a circular base, a guide is arranged circumferentially on the outer edge of the production area (1) and above the surface of the powder bed, and the at least one doctor blade (3) is arranged such that it is slidably mounted on two opposite points of the guide. [2] Device according to claim 1, characterized by, that a greater distance between the nozzles is maintained on the at least one squeegee (3) in the area of ​​the axis of rotation in order to discharge less powdered material onto the surface of the powder bed in an area near the axis of rotation (4) than in areas near the edge. [3] Device according to any one of the preceding claims, characterized by , that the control of the at least one energy beam is adjusted so that the at least one energy beam does not hit the at least one squeegee (3). [4] Device according to any one of the preceding claims, characterized by , that in the at least one doctor blade (3) a screw conveyor and / or a pneumatic feeder for conveying the powdered material to the nozzles of the doctor blade (3) is formed. [5] Device according to any one of the preceding claims, characterized by, that several squeegees (3) are arranged above the surface (2) of the manufacturing area (1) and that different powdered materials and / or powdered materials with different mean particle size ranges can be applied to the surface of the powder bed with the squeegees (3). [6] Device according to any one of the preceding claims, characterized by , that the at least one squeegee (3) has several arms extending from the axis of rotation. [7] Device according to any one of the preceding claims, characterized by , that a device for local preheating of the powdered material, preferably by means of infrared radiation or induction, and / or a scraper is / are arranged rotating around the axis of rotation (4). [8] Device according to any one of the preceding claims, characterized by, that the manufacturing area (1) is divisible into at least two working areas and that three-dimensional bodies (5) can be produced simultaneously in each working area. [9] Device according to any one of the preceding claims, characterized by , that the axis of rotation (4) of the squeegee (3) is arranged at a distance from the central or surface center of gravity of the manufacturing area (1).

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