METHOD FOR OPERATING AN APPARATUS FOR ADDITIVELY MANUFACTURING THREE-DIMENSIONAL OBJECTS

Abstract

Method for operating an apparatus (1) for additively manufacturing three-dimensional objects (2) by means of successive layerwise selective irradiation and consolidation of layers of a build material (3) which can be consolidated by means of an energy beam (5), wherein at least one region in a build plane (6) is irradiated in the additive manufacturing process, wherein an interrupted state of the additive manufacturing process is determined and a defined amount of energy is deposited in at least one previously irradiated region (7, 8) of the build plane (6) in an interrupted state of the additive manufacturing process.

Claims

1. Method for operating an apparatus (1) for additively manufacturing three-dimensional objects (2) by means of successive layerwise selective irradiation and consolidation of layers of a build material (3) which can be consolidated by means of an energy beam (5), wherein at least one region in a build plane (6) is irradiated in the additive manufacturing process, characterized by determining an interrupted state of the additive manufacturing process and depositing a defined amount of energy in at least one previously irradiated region (7, 8) of the build plane (6) in response to the interrupted state of the additive manufacturing process.

2. Method according to claim 1, characterized in that the interrupted state is an exchange process of at least one component of the apparatus (1), in particular a powder module of the apparatus (1), and/or a refill process in which at least one material of the apparatus (1), in particular build material (3), is refilled and/or a calibration process of at least one component and/or a calculation process, in particular for calculating build data.

3. Method according to claim 1, characterized in that the interrupted state continues for a defined time, preferably for at least 10 seconds, in particular for at least 120 seconds.

4. Method according to claim 1, characterized by generating interruption information relating to the interrupted state of the additive manufacturing process performed on the apparatus (1) and depositing the defined amount of energy in the at least one previously irradiated region (7, 8) of the build plane (6) dependent on the interruption information.

5. Method according to claim 1, characterized by compensating a heat dissipation from the at least one previously irradiated region (7, 8) via the deposition of the defined amount of energy.

6. Method according to claim 1, characterized by heating the at least one previously irradiated region (7, 8) to a defined target temperature.

7. Method according to claim 6, characterized by choosing the defined target temperature in that the build material (3) in the region remains in the same consolidation state as before the interruption, in particular remains molten.

8. Method according to claim 1, characterized by depositing a different defined amount of energy for at least two different previously irradiated regions (7, 8), in particular dependent on the corresponding cross-section of the object (2) in the actual layer.

9. Method according to claim 6, characterized by determining the temperature of the at least one previously irradiated region (7, 8) and adjusting the defined amount of energy dependent on the determined temperature and the defined target temperature.

10. Method according to claim 1, characterized by adjusting the defined amount of energy dependent on a desired temperature gradient between the at least one previously irradiated region (7, 8) and at least one adjacent region and/or a desired heat flow in the build plane (6).

11. Method according to claim 1, characterized by using the same energy beam (5) for depositing the defined amount of energy that is used for irradiating the build material (3), preferably with a reduced intensity.

12. Method according to claim 1, characterized by defining a maximum amount of energy so as to avoid a structural change of the build material (3) in the at least one previously irradiated region (7, 8).

13. Method according to claim 1, characterized by guiding the energy beam (5) along a heating track across the at least one previously irradiated region (7, 8).

14. Method according to claim 1, characterized by guiding the energy beam (5) continuously or for a defined number of turns along the heating track during the interrupted state, preferably dependent on the interruption information.

15. Method according to claim 1, characterized by continuing the additive manufacturing process dependent on the interruption information.

16. Irradiation device (4) for an apparatus (1) for additively manufacturing three-dimensional objects (2) by means of successive layerwise selective irradiation and consolidation of layers of a build material (3) which can be consolidated by means of an energy beam (5), wherein the irradiation device (4) is adapted to irradiate at least one region in a build plane (6) during the additive manufacturing process with the energy beam (5), characterized in that the irradiation device (4) is adapted to deposit a defined amount of energy in at least one previously irradiated region (7, 8) of the build plane (6) in response to a determined interrupted state of the additive manufacturing process performed on the apparatus (1).

17. Apparatus (1) for additively manufacturing three-dimensional objects (2) by means of successive layerwise selective irradiation and consolidation of layers of a build material (3) which can be consolidated by means of an energy beam (5), characterized by an irradiation device (4), in particular an irradiation device (4) according to claim 16, which irradiation device (4) is adapted to deposit a defined amount of energy in at least one previously irradiated region (7, 8) of the build plane (6) in response to a determined interrupted state of the additive manufacturing process performed on the apparatus (1).

Description

[0028] An exemplary embodiment of the invention is described with reference to the FIGURE The sole FIGURE is a schematic diagram showing an inventive apparatus.

[0029] The sole FIGURE shows an apparatus 1 for additively manufacturing three-dimensional objects 2 by means of successive layerwise selective irradiation and consolidation of a build material 3. The apparatus 1 comprises an irradiation device 4 that is adapted to generate and guide an energy beam 5 across a build plane 6, i.e. the plane in which the build material 3 is arranged to be irradiated in a regular mode of operation of the apparatus 1. In other words, the energy beam 5 can be selectively guided across the build plane 6 to irradiate and thereby consolidate the build material 3 to build the object 2 in a layerwise successive manner.

[0030] In the situation that is depicted in the FIGURE, an interruption of the additive manufacturing process occurs. Hence, the previously irradiated regions 7, 8 would cool down without a suitable deposition of energy due to heat dissipation in the surrounding build material 3 or the atmosphere inside the process chamber 9, for instance. To avoid the cooling of the previously irradiated regions 7, 8 and thereby avoiding negative impacts on the irradiation process, the irradiation device 4 is adapted to deposit a defined amount of energy via the energy beam 5 in the previously irradiated regions 7, 8 of the build plane 6 during/in the interrupted state.

[0031] Hence, it is possible to compensate the heat dissipation from the previously irradiated regions 7, 8 via a deposition of the defined amount of energy that heats the previously irradiated regions 7, 8 accordingly to maintain the temperature and the consolidation state of the previously irradiated regions 7, 8. In particular, it is possible that the consolidation state of the previously irradiated region 7, 8 can be maintained during the interruption of the additive manufacturing process, preferably multiple parts of the previously irradiated regions 7, 8 can remain molten.

[0032] As can further be derived from the FIGURE, the apparatus 1 comprises a control unit 10, which is, inter alia, adapted to generate interruption information relating to the interrupted state of the additive manufacturing process, e.g. the duration of the interruption of the manufacturing process. Hence, the value of the defined amount of energy can be stored or generated in the control unit 10 or received via the control unit 10. Consequently, the control unit 10 may provide the interruption information and/or the value of the defined amount of energy to the irradiation device 4 in that at least one parameter of the energy beam 5 can be adjusted accordingly to ensure that the correct amount of energy is deposited in the previously irradiated regions 7, 8.

[0033] It is also possible to define a target temperature, e.g. the temperature the previously irradiated regions 7, 8 were heated to before the additive manufacturing process was interrupted. The apparatus 1 further comprises a temperature determination unit 11 that is adapted to determine the actual temperature of the build material 3 in the previously irradiated regions 7, 8. Thus, a closed loop control can be performed, as the temperature of the previously irradiated regions 7, 8 can be determined via the temperature determination unit 11, wherein the determined temperature can be compared with the defined target temperature. If a deviation between the defined target temperature and the determined temperature occurs, the build material 3 in the corresponding previously irradiated regions 7, 8 can be heated via the energy beam 5. For example, if the determined temperature is beneath the defined target temperature, the defined amount of energy can be increased to ensure that the build material 3 in the previously irradiated regions 7, 8 is heated to the defined target temperature.

[0034] It is further possible that the defined amount of energy is adjusted dependent on a desired temperature gradient between the at least one previously irradiated region 7, 8 and at least one adjacent region, e.g. surrounding build material 3 and/or a desired heat flow in the build plane 6. To ensure that the correct amount of energy can be deposited in each previously irradiated region 7, 8, a different defined amount of energy can be deposited for at least two different previously irradiated regions 7, 8. For example, the previously irradiated regions 7, 8 differ in size, underground and geometry, wherein due to two different defined amounts of energy it is assured that both previously irradiated regions 7, 8 can maintain the consolidation state, as described before. By taking the size and the geometry of the previously irradiated regions 7, 8 into calculation it is possible to define the amount of energy that is necessary to maintain the consolidation state, in particular maintain the defined target temperature. It is further possible to take the underground into calculation, as the underground of the previously consolidated region 7, 8 defines or affects the heat dissipation from the uppermost layer of build material 3.

[0035] For example, the previously irradiated region 7 is based on top of a partially built object 2, wherein the consolidated part beneath the previously irradiated region 7 leads to improved heat dissipation and therefore, more energy is required to keep the previously irradiated region 7 on the defined target temperature. The previously irradiated region 8 is based on non-consolidated build material 3 and therefore, the heat dissipation is not as large as the heat dissipation of the previously irradiated region 7. Thus, a comparatively minor amount of energy is sufficient to heat the previously irradiated region 7 to the defined target temperature. Of course, other parameters can be taken into calculation besides the size, the underground and the geometry.

[0036] Hence, a heating track can be defined along which the energy beam 5 can be guided across the build plane 6 to deposit the defined amount of energy to each previously irradiated region 7, 8 and properly distribute the energy in each previously irradiated region 7, 8. In this exemplary embodiment, the energy beam 5 is used to irradiate and consolidate the build material 3 in the regular mode of operation of the apparatus 1 and in the interrupted state of the additive manufacturing process, the energy beam 5 is used to heat the previously irradiated region 7, 8, as described before.

[0037] After the interruption of the additive manufacturing process is over, the additive manufacturing process can be continued from where it ended/was interrupted by the interruption. Of course, any arbitrary other arrangement of the apparatus can be used to perform the additive manufacturing process, in particular a height-adjustable carrier element is not necessary. Self-evidently, the inventive method can be performed on the apparatus 1, preferably using the inventive irradiation device 4.