Method for producing a three-dimensional object

Abstract

Method for producing a three-dimensional object (1) by successively solidifying layers of a building material (3) that can be solidified by means of an electron beam, electromagnetic radiation (2), or particle radiation, at the locations corresponding to the respective cross-section (4) of the object (1), wherein during a coating process A, B, powder-like building material (3) is displaced from a metering area (6) into a construction area (7) by means of a substantially horizontally movable coating device (5), wherein the coating device (5) is moved at least two different speeds v1, v2, v3, v4, v5, v6 within a coating process for applying a layer of building material (3), wherein the coating process A, B comprises both a forward movement A directed towards the construction area (7) and a backward movement B of the coating device (5), characterized in thatthat the coating device (5) is moved at different speeds in at least two sections S1, S2, S3, S4, S5, S6 within the forward or return movement A, B, wherein the coating device (5) has a first speed v1 in a first section S1 up to the area (13) of the cross-section (4) of the object (1) to be solidified, a second speed v2 in a second section S2 which essentially corresponds to the object cross-section (4) of the object (1) to be solidified, and a third speed v3 in a third section S3 which begins after the respective cross-section (4) of the object (1) and the coating device (5) moves away from the object (1), wherein the second speed v2 is lower than the first and / or third speeds v1, v3.

Description

[0001] The invention relates to a method for producing a three-dimensional object by successively solidifying layers of a building material which can be solidified by means of electromagnetic radiation or particle radiation, at the locations corresponding to the respective cross-section of the object, wherein during a coating process powder-like material is displaced from a dosing area into a construction area by means of a substantially horizontally movable coating device.

[0002] A method for producing a three-dimensional object by successively solidifying layers of a powder-like material is known from the prior art, cf. DE 103 00 959 B4.

[0003] Further state of the art regarding the technological background is provided by the disclosures of the documents DE 195 14 740 C1, DE 103 00 959 B4 and DE 10 2007 040 755 A1.

[0004] The invention is based on the object of developing a method for producing a three-dimensional object with the features of the preamble of claim 1 in such a way that the construction process of the object can be carried out more quickly. Furthermore, the object is to achieve high accuracy in the object despite the faster construction of the object, while simultaneously achieving this with simple means.

[0005] This object is achieved by the features of claim 1 and the device according to claim 14. Advantageous developments of the invention emerge from the subclaims.

[0006] The core of the invention is considered to be that the coating device is moved at at least two different speeds during a coating process for applying a layer of powder. The coating process includes both a forward movement of the coating device toward the construction area and a return movement of the coating device, and the coating device is moved at different speeds in at least two sections of the forward or return movement. Because the coating device is moved at different speeds (average speed) over at least two sections of the forward or return movement during the coating process, the speed of the coating device can be adapted to the requirements of the respective section of the coating device.

[0007] For example, if the coating device has different speeds on two sections of the outward movement, it may be possible to travel at a lower speed on a first section, which extends to the end of the build platform, than on a subsequent section. The slower the coating device travels, the lower the risk of uneven application of the build material. Particularly in sections outside the build area, a relatively high speed can preferably be used, while a relatively lower speed can be used while the coating device is moving over the build area, since an exact, level application of the build material is only necessary in the build area to achieve a precise object.

[0008] According to the invention, the coating device has a first speed in a first section up to the area of ​​the cross-section of the object to be solidified, a second speed in a second section, which essentially corresponds to the cross-section of the object to be solidified, and a third speed in a third section, which begins after the respective cross-section of the object and moves the coating device away from the object, wherein the second speed is lower than the first and / or the third speed. The forward movement of the coating device is thus divided into at least three sections, wherein the first transports the powder to the object, the second section draws up the powder in the area of ​​the object to be solidified, and the third layer moves the coating device away from the construction area after the area of ​​the object.The speed of the second section should be lower because precise leveling of the building material is important in this section, and this can be ensured by moving the coating device more slowly. The speed of the third section is preferably higher than that of the first section. Since even more building material needs to be transported in the first section, the speed should be lower there than in the third section to ensure reliable transport of the powder material. In this respect, it is not problematic to move the coating device faster in the third section, since neither targeted leveling of the building material nor such reliable transport of the powder material is important there.

[0009] In an embodiment of the invention, the coating device experiences a negative acceleration at least in the second half of the first section, in particular 2-50 mm before the cross-section of the object to be solidified, or stops there at least for a short time (t=0.1 - 3.0 s). The second half of the first section, which is preferably located directly upstream of the second section, serves to "calm down" the building material, in particular the powder-like building material. Because the coating device experiences a deceleration in the second half of the first section, the kinetic energy transferred to the building material is reduced, thus mitigating the risk of the building material "jumping" uncontrollably in the area of ​​the second section despite the change (reduction) in speed from the first to the second section.This can happen in particular when the coating device comes to a standstill after changing from a first section of the track to a further section. It can also be provided that the speed change of the coating device from a first section to a further section occurs continuously, for example, the coating device is changed by a constant acceleration or deceleration from a first speed of a first section of the track to a second speed of a further section of the track. The coating device can also experience an acceleration, a deceleration, or a stop (standstill) in the section of the track following the cross-section of the object (e.g., 2 - 50 mm after the object cross-section).

[0010] With a view to achieving the highest possible process speed, it is advantageous if, in addition to the speed change during the forward or return movement, the speed in at least one section of the forward movement is lower than the speed in a section of the return movement. Furthermore, it is advantageous if the coating device is moved during the return movement at a speed that is essentially equal to or higher than the speed of the third section. For example, it can be a coating device that only transports building material in one direction of travel and, during the return movement, merely returns the coating device to its starting position without displacing powder material like a doctor blade.If this is the case, the coating device can have a speed during the return movement that is equal to or even higher than the highest speed during the outward movement.

[0011] Furthermore, it can be provided that the coater device is raised or pivoted at least partially from its horizontal coating plane during the return movement. By raising or "pivoting up" the coater device from the horizontal coating plane of the forward movement, any influence (contact, turbulence) on the build material applied during the forward movement can be avoided during the return movement of the coater and ultimately a higher or maximum speed of the coater can be achieved. By the return movement of the coater devices in a raised plane, the return movement of the coater and thus the process speed of the entire method can be increased. It is also sufficient to raise the leveling element, e.g. a squeegee, from the build level instead of the entire coater.

[0012] Furthermore, it is advantageous if the coating device can be relocated under computer control, and if relocation data, in particular speed data and / or coating position data associated with the respective track sections, can be read out or entered into a data storage device or via an input unit. The relocation data can include data on the speed, acceleration, deceleration, and / or the positions of the individual track sections. For example, the relocation data from the data storage device takes into account the type of building material, the object geometry, and / or the thickness of the building layer to control the relocation of the coating unit (speed, acceleration, height of the coating device).

[0013] The displacement data can be used for both individual and groups of build-up layers to control the coating system. This means that, for example, the displacement data, such as the speed, acceleration, and / or elevation of the coating system, remain the same in individual track sections across multiple groups of successively applied build-up layers.

[0014] The type of building material can affect the grain size, flowability, density, and / or grain distribution. These specifications of the building material provide information about the behavior of the building material during its displacement by the coating device. It is therefore advantageous to incorporate the specifications of the building material into the displacement data of the coating device. For example, the return speed of a coating device raised from the coating level can be selected depending on the grain size, flowability, density, and / or grain distribution of a building material. This means that for building materials that behave "rather sluggishly," a higher travel speed of the coating device can be selected, since the air / gas turbulence caused by this has little or no effect on the building material already applied.

[0015] The invention further comprises a device for producing a three-dimensional object by successively solidifying layers of a building material that can be solidified by means of electromagnetic radiation or particle radiation at the respective cross sections of the object. This device uses a coating device that is moved at at least two different speeds within a forward or backward movement during a coating process for applying a layer of powder. This means that the device preferably displaces the coating device under computer control, and displacement data is incorporated into this control.

[0016] In a particularly advantageous embodiment, not only the object contour to be lasered into the layer to be applied is considered for defining the individual sections of the coating device, but also at least the subsequent layer. By taking into account not only the component contour to be coated and solidified in the respective coating process, but also at least the subsequent layer, the subsequent coating processes can be more precisely leveled, at least in the area of ​​the object areas to be solidified in the subsequent layers, in the case of overhangs or projections of the object, and thus the object can be manufactured more precisely.

[0017] The invention is explained in more detail using exemplary embodiments in the drawing figures. These show Fig. 1: a schematic representation of an apparatus for producing a three-dimensional object by successively solidifying layers by means of electromagnetic radiation; Fig. 2: a schematic detailed representation according to Fig. 1, with the coating device in a first section; Fig. 3: a schematic representation according to Fig. 2, with the coating device in a second section; Fig. 4: a schematic representation according to Fig. 3, with the coating device in a third section; Fig. 5: a schematic representation according to Fig. 4, with the coating device in a raised, fourth section; Fig. 6: a schematic representation according to Fig. 3, where the route sections are defined based on the maximum cross-sectional contour of the object; Fig. 7: a schematic representation according to Fig. 3, with an alternative object geometry.

[0018] Figure 1 shows a method for producing a three-dimensional object 1, in which, by successively solidifying layers of a building material 3 by means of electromagnetic radiation 2 or particle radiation, the building material 3 is selectively melted and solidified at the locations corresponding to the respective cross-section 4 of the object 1. During a coating process, the building material 3, in particular in powder form, is moved from a dosing area 6 to a build area 7 by means of a substantially horizontally movable coating device 5. In the illustrated embodiment, the dosing area 6 is represented as a lifting cylinder in which a carrier element 8 carrying the building material 3 lifts the building material 3 stored there above a build level 9 and moves this material via the coating device 5 from the dosing area 6 by acting on the doctor blade 10 of the coating device 5 to the build area 7.Alternatively, the build material 3 can also be fed into the build area 7 from above. For this purpose, a screen coater arranged above the build area 7 can be provided, for example. A build material storage chamber can also be arranged on the coater device 5, which continuously or in phases applies build material 3 to a leveling element of the coater device 5 (not shown).

[0019] The build level 9 forms the upper edge of the material layer to be solidified, onto which the radiation 2 from the laser 11 impinges. The build area 7 also has a carrier 12, on which an object 1 is built either directly or indirectly via a build platform. For this purpose, the build material 3 applied by the squeegee 10 is leveled to the build level 9 so that the radiation 2 can be specifically applied to the leveled powder layer in order to selectively produce the object 1 to be formed. After a layer has been built up in the build area 7, the carrier 12 is moved down by one layer thickness, and the space thus formed between the build level 9 and the last applied powder layer in the build area 7 is filled with build material 3 by moving the coating device 5, so that a further layer solidification process can be carried out.

[0020] It can also be provided that a dosing area 6 or an overflow area is arranged at two opposite end areas of the build area 7, into which the build material 3 displaced "excessively" over the build area 7 by the coating device 5 can be introduced. Both the actuators for vertically displacing the supports 8, 12 and the actuator for displacing the coating device 5 are preferably controlled via a computer 17. The coating process A, B comprises both an outward movement A directed towards the build area and a return movement B of the coating device 5, wherein the speed v1, v2, v3, v5, v6 is lower, at least in a section S1, S2, S3, S5, S6 of the outward movement A, than a further speed v1, v2, v3, v5, v6 in a section S1, S2, S3, S5, S6 of the outward movement A.

[0021] Figures 2-5 show a preferred embodiment of the movement of the coating device 5, wherein the path sections S1, S2, S3, S4, S5, S6 are defined such that the first path section S1 extends from the dosing area 6 to the initial area 13 of the cross-sectional contour 4 of the object 1. The second path section S2 extends from the initial area 13 to the end area 14 of the object contour 4. In the illustrated embodiment, the path S2 corresponds to the area to be solidified in the layer to be built up on the object 1.

[0022] The section S3 begins at the end region 14 and, in the illustrated embodiment, leads to the overflow or the further dosing region 15, i.e., to a displacement of the build material 3 away from the object 1 to be formed. The fourth section S4 corresponds to the return movement B, whereby, according to drawing figure 5, the coating device 5 is raised from its original plane, in which the free end of the squeegee 10 touches the build plane level 9. In the raised position, the free end 16 of the squeegee 10 is spaced from the build plane level 9. In this raised position, the coating device 5 is moved back to the dosing region 6. This closes the circle of the section sections, so that the coating device 5 executes a recurring movement. The individual sections S1, S2, S3, S4, S5, S6 are assigned respective speeds v1, v2, v3, v4, v5, v6 with the corresponding indices.

[0023] In the embodiments illustrated in Figures 2-5, the path sections S1, S2 are defined by the start and end regions 13 or 14. Orientation is based on the cross-section 4 of the object 1 of the last material layer formed or of the material layer to be formed. Alternatively, the regions 13 and 14 can also be provided in the region of the maximum cross-sections 4 of the object 1; see reference numerals 13', 14', which define the maximum cross-sectional extent of the object 1 to be formed over its entire height and can also be used to define the path, see Fig. 6. If the distances S1, S2, S3, S4 are defined with the areas 13', 14', the distances as well as the speeds of the coating device 5 remain constant throughout all coating processes A, B of the entire component 1.

[0024] If, however, the areas 13, 14 are each oriented toward the cross-section 4 of the object 1 to be formed, the distances S1, S2, S3, S4, S5, S6 can, for example, be different for each component layer. It is also possible to define the distances S1, S2, S3, S4, S5, S6 after a predefined number of component layers (group) in such a way that the maximum cross-section 4 for defining the areas 13' and 14' is kept constant for each group of component layers, and the distances S1, S2, S3, S4, S5, S6 are kept constant within the group.

[0025] Based on the process sequence shown in Figures 2 - 5, advantageous speed relations for the respective route sections S1, S2, S3, S4 are presented below.

[0026] In principle, it is advantageous if the coating device 5 is moved at different speeds v1, v2, v3, v4 in at least two sections S1, S2, S3, S4 within the forward and / or return movement A, B. In particular, if the coating device 5 has a first speed v1 in a first section S1 up to the region 13 of the cross-section 4 of the object 1 to be solidified, and a second speed v2 in a second section S2 which essentially corresponds to the cross-section 4 of the object 1 to be solidified (section between the regions 13 and 14), and a third speed v3 in a third section S3 which begins after the respective cross-section 4 (after the region 14) of the object 1 and the coating device 5 moves away from the object 1, the second speed v2 can be selected to be lower than the first and / or third speeds v1, v3.

[0027] In particular, the speed v3 of the third section S3 should be set higher than the speed v1 of the first section, since the coating device 5 has to transport more building material 3 in the first section S1 than in the section S3. Furthermore, for precise production of the object 1, exact leveling of the building material 3 after the object 1, i.e., after the area 14, is not necessary.

[0028] Furthermore, it can be provided that the coating device 5 experiences a negative acceleration (deceleration) at least in the second half of the path S1' of the first path section S1, in particular 2 - 50 mm before the cross-section 4 of the object 1 to be solidified. Because, in the illustrated embodiment of the coating device 5, the squeegee 10 with the building material 3 pushed in front of it also influences areas in front of the squeegee 10, it can be advantageous to slow down the coating device 5 before reaching area 13 so that the building material 3 displaced by the coating device 5 is not displaced into the path area 2 in an uncontrolled manner or at its high speed.

[0029] The speed change of the coating device 5 can be carried out either continuously or by stopping between two track sections. Particularly when the coating device 5 is stopped during the change from a first to a subsequent track section S1, S2, S3, S4, S5, S6, it is advantageous to slow down the coating device 5 before reaching track section 2.

[0030] Preferably, the change in the speed v1, v2, v3, v4, v5, v6 of the coating device 5 occurs with a constant acceleration or deceleration.

[0031] The duration of the entire process can be reduced by moving the coating device 5 during the return movement B at a speed v4 that essentially corresponds to or is higher than the highest speed v1, v2, v3 of the forward movement A. In particular, if the device is provided with an overflow area 15 and therefore the coating device 5 no longer displaces any build-up material 3 during the return movement B, the function during the return movement B lies exclusively in moving the coating device 5 back and can therefore be performed at a higher speed value regardless of the build-up material 3 to be transported.This can be further enhanced by raising the coating device 5 at least in some areas during the return movement B from a horizontal coating plane, i.e. the build-up plane level 9, thereby eliminating the risk that the doctor blade 10 of the coating device 5 touches, displaces or damages solidified or unsolidified build-up material 3 during a rapid return movement.

[0032] The coating device 5 can preferably be displaced under computer control via an actuator 20, wherein a data memory 18 is attached to this computer 17 and displacement data for the respective track sections S1, S2, S3, S4, S5, S6 can be stored, read out, or entered via the data memory 18 and / or the input unit 19. When using a data memory 18, it is advantageous to modify the speed data to control the travel speed of the coating device 5 depending on the type of building material, the object geometry, and / or the construction layer thickness. This means that, for example, the data memory 18 stores different speed data depending on the type of building material, the object geometry, and / or the construction layer thickness and / or can be entered via an input unit 19.The displacement data, and in particular the speed data, can be used both individually and on groups of build-up layers to control the coating device 5.

[0033] The type of building material may include information about the grain size, flowability, density, and / or grain distribution, with the effects of these respective attributes of the building material 3 being used in the calculation or determination of the displacement data, in particular the speed data of the coating device 5. For example, a higher speed of the coating device 5 can be provided for a building material 3 with easy flow than for a building material with low flowability.

[0034] In drawing Figure 7, the method according to the invention is shown for an object 1 which has at least two surfaces spaced apart from one another. What is important for the speeds v1, v2, v3, v4, v5, v6 is that the distance between the two surfaces is moved over the section S3 at a coating speed v5. The second surface coated by the coater 5 represents the section S6 and is traveled over at the speed v6, wherein the speed v6 is preferably lower than the speed v5. Preferably, the speed v5 is selected to be the same as or similar to the speed v2 of the second section S2. The speed v5 of the section S5 is preferably selected to be the same as or similar to the speed v1 of the section S1.This allows a higher travel speed of the coating device to be selected in the space between two areas (surfaces) of the object 1 that are not to be solidified, thus reducing the production time of the entire device. LIST OF REFERENCE SYMBOLS A forward movement v. 5 B Backward movement of 5 1 object 2 Radiation 3 Construction material 4 Cross section 5 Coating device 6 Dosing range 7 Construction area 8 support element 9 superstructure level 10 squeegees 11 lasers 12 carriers 13, 13' Initial area of ​​4 14, 14' end area of ​​4 15 Dosing or overflow area 16 Free End v. 10 17 computers 18 data storage 19 Input unit 20 Actuator v. 5 S1 - S6 route

Claims

[1] Method for producing a three-dimensional object (1) by successively solidifying layers of a building material (3) which can be solidified by means of an electron beam, electromagnetic radiation (2) or particle radiation, at the locations corresponding to the respective cross-section (4) of the object (1), wherein during a coating process A, B, powder-like building material (3) is displaced from a metering area (6) into a construction area (7) by means of a substantially horizontally movable coating device (5), wherein the coating device (5) is moved at least two different speeds v1, v2, v3, v4, v5, v6 within a coating process for applying a layer of building material (3), wherein the coating process A, B comprises both a forward movement A directed towards the construction area (7) and a backward movement B of the coating device (5), characterized byin that the coating device (5) is moved at different speeds in at least two sections S1, S2, S3, S4, S5, S6 within the forward or within the return movement A, B, wherein the coating device (5) has a first speed v1 in a first section S1 up to the area (13) of the cross-section (4) of the object (1) to be solidified, and a second speed v2 in a second section S2 which essentially corresponds to the object cross-section (4) of the object (1) to be solidified, and a third speed v3 in a third section S3 which begins after the respective cross-section (4) of the object (1) and the coating device (5) moves away from the object (1), wherein the second speed v2 is lower than the first and / or third speed v1, v3. [2] Method according to claim 1, characterized bythat the speed v1, v2, v3, v4, v5, v6 at least in a section S1, S2, S3, S5, S6 of the outward movement A is lower than the speed v4 in a section S4 of the return movement B. [3] Method according to claim 1 or 2, characterized by that the speed v3 of the third track section S3 is higher than the speed v1 of the first track section S1. [4] Method according to one of the preceding claims, characterized by that the coating device (5) experiences a negative acceleration or is stopped at least in the second half of the section S1' of the first section S1, in particular 2 - 50 mm before the cross-section (4) of the object (1) to be solidified. [5] Method according to one of the preceding claims, characterized by that the coating device (5) comes to a standstill when changing from a first section S1 to a further section S2. [6] Method according to one of claims 1 to 4, characterized by that the speed change of the coating device (5) from a first to a further section S1, S2 takes place continuously. [7] Method according to one of the preceding claims, characterized by that the change in the speed v1, v2, v3, v4, v5, v6 of the coating device (5) occurs with a constant acceleration or deceleration. [8] Method according to one of the preceding claims, characterized by that the coating device (5) is moved during the return movement B at a speed v4 which essentially corresponds to or is higher than the highest speed v1, v2, v3, v5, v6 of the outward movement A. [9] Method according to one of the preceding claims, characterized bythat the coating device (5) is raised or pivoted at least in some areas from a horizontal coating plane during the return movement B (fourth section S4). [10] Method according to one of the preceding claims, characterized by that the coating device (5) can be displaced under computer control and displacement data of the respective route sections S1, S2, S3, S4, S5, S6 are read out or entered in a data memory (18) and / or via an input unit (19). [11] Method according to claim 10, characterized by that speed data for controlling the travel speed v1, v2, v3, v4, v5, v6 of the coating device (5) are input from the data memory (18) depending on the type of building material (3), object geometry and / or building layer thickness. [12] Method according to claim 11, characterized bythat the speed data for individual or groups of build-up layers are used to control the coating device (5). [13] Method according to claim 11 or 12, characterized by that the nature of the building material (3) affects its grain size, flowability, density and / or grain distribution. [14] Device for producing a three-dimensional object (1) by successively solidifying layers of a building material (3) which can be solidified by means of electromagnetic radiation (2) or particle radiation at the respective cross sections (4) of the object (1), characterized by that the device is designed to carry out a method according to one of the preceding claims.

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