METHOD AND DEVICE FOR THE ADDITIVE PRODUCTION OF A COMPONENT AND COMPONENT

Abstract

A method for the additive production of a component, wherein a plurality of layers made in particular of a powder-like material is provided in succession and each material layer is scanned by an energy beam according to a specified component geometry. A component section already produced and/or the respective material layer provided and/or of a work platform on which the component is constructed is additionally heated. For at least one material layer, the temperature distribution on the surface on which the material layer is provided and/or the temperature distribution on the surface of the layer provided is measured. During the scanning process of the material layer, the energy quantity introduced by the energy beam is varied as a function of the temperature distribution detected on the surface on which the layer is provided, and/or as a function of the temperature distribution detected on the surface of the layer.

Claims

1.-13. (canceled)

14. A method for the additive production of a component, comprising: successively providing a plurality of layers, more particularly a plurality of layers of a powdery material; scanning each material layer by at least one energy beam, more particularly at least one laser beam, according to a specified component geometry; and additional heating of an already produced component section, and/or of the respectively provided material layer, and/or of a work platform on which the component is constructed; wherein, for at least one material layer, in particular for each material layer, the temperature distribution on the surface on which the material layer is provided is captured using measurement technology, in particular prior to the provision of the layer, and/or the temperature distribution on the surface of the provided layer is captured using measurement technology; wherein, within the scope of the procedure of scanning over the material layer, varying the amount of energy introduced by the at least one energy beam depending on the captured temperature distribution on the surface on which the layer is provided and/or depending on the captured temperature distribution on the surface of the layer, in particular varied in such a way that an inhomogeneity of the temperature distribution is reduced or compensated; wherein the temperature distribution on the surface on which the material layer is provided is captured using measurement technology by virtue of a thermal image of this surface being recorded by means of a thermographic camera, and/or the temperature distribution on the surface of the material layer is captured using measurement technology by virtue of a thermal image of the surface of the material layer being recorded by means of a thermographic camera; wherein at least one captured thermal image is evaluated, and the amount of energy introduced by the at least one energy beam is varied depending on the result of the evaluation; and wherein at least one temperature gradient is calculated on the basis of the thermal image and the amount of energy introduced by the at least one energy beam is varied during the scanning procedure depending on the calculated temperature gradient.

15. The method as claimed in claim 14, wherein for the first and lowermost material layer, the temperature distribution on the surface of a work platform on which the first layer is provided is captured using measurement technology, in particular prior to the provision of the first layer, and, wherein, within the scope of the procedure of scanning over the first layer, the amount of energy introduced by the at least one energy beam is varied depending on the captured temperature distribution on the surface of the work platform.

16. The method as claimed in claim 14, wherein the amount of energy introduced by the at least one energy beam during the scanning procedure is varied by virtue of the intensity and/or the power and/or the pulse duration and/or the beam or focal diameter and/or the displacement speed of the at least one energy beam and/or the density of scanning vectors, more particularly scanning lines, along which the at least one energy beam is moved over the material layer, being varied during the scanning procedure.

17. The method as claimed in claim 14, wherein the variation during the scanning procedure is such that the amount of energy introduced by the at least one energy beam is increased where there is a comparatively lower temperature according to the captured temperature distribution, and/or the amount of energy introduced by the at least one energy beam is reduced where there is a comparatively higher temperature according to the captured temperature distribution.

18. The method as claimed in claim 14, wherein the temperature distribution is captured at least over that region of the surface over which the region of the material layer to be scanned extends.

19. The method as claimed in claim 14, wherein the additional heating of the respectively provided material layer and/or of an already produced component section and/or of a work platform on which the component is constructed is brought about in inductive fashion by means of at least one induction coil.

20. A component, in particular for a turbomachine, produced according to the method as claimed in claim 14.

21. An apparatus for the additive production of a component, the apparatus comprising: a work region, defined above a work platform, means for providing material layers, preferably powdery material layers, above one another in the work region, an energy beam device, more particularly a laser beam device, which is embodied and configured to emit at least one energy beam, more particularly at least one laser beam, and scan over material layers provided in the work region with the at least one energy beam, more particularly the at least one laser beam, according to a specified component geometry, means for heating, more particularly inductively heating, a material layer provided in the work region and/or an already produced component section and/or the work platform, capturing means which are embodied to use measurement technology to capture the temperature distribution on the surface of the work platform and/or on a component section already produced above the work platform and/or on a material layer provided on the work platform or on an already produced component section, control means which are embodied and configured to vary the amount of energy introduced during a scanning procedure by at least one energy beam, provided by the energy beam device, depending on a temperature distribution captured by the capturing means, in particular to vary said amount of energy introduced in such a way that an inhomogeneity in the temperature distribution is compensated or reduced.

22. The apparatus as claimed in claim 21, wherein the capturing means comprise at least one thermographic camera or are provided by the latter and/or the heating means comprise at least one induction coil or are provided by the latter.

23. An apparatus, for the additive production of a component, the apparatus comprising: a control means embodied and configured to carry out the method as claimed in claim 14.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Further features and advantages of the present invention will become evident from the following description of exemplary embodiments of the apparatus according to the invention and of the method according to the invention, with reference being made to the drawing. In the drawing:

[0049] FIG. 1 shows a purely schematic perspective view of an apparatus for the additive production of a component according to an embodiment of the present invention;

[0050] FIG. 2 shows a purely schematic sectional illustration of the apparatus of FIG. 1;

[0051] FIG. 3 shows a graph where the temperature curve is plotted along a specified line through a thermal image of the surface of an already produced component section, which was captured by means of the thermographic camera of the apparatus of FIG. 1; and

[0052] FIG. 4 shows a graph where a curve of the laser power, which compensates the temperature curve from FIG. 3, is plotted in comparison with the constant laser power as per the prior art.

DETAILED DESCRIPTION OF INVENTION

[0053] FIGS. 1 and 2 show purely schematic and greatly simplified illustrations of an exemplary embodiment of an apparatus according to the invention for the additive production of a component, an already produced component section 1 of which being evident in the figures. FIG. 1 shows a perspective view and FIG. 2 shows a sectional view. It should be noted that some components of the apparatus are not illustrated in both figures; however, they can be gathered from the respective other figure.

[0054] As is sufficiently well known from the prior art, the apparatus comprises a work space 3 defined by a cylinder 2, a work platform 4 being disposed in vertically displaceable fashion in said work space above a stamp 5. Cylinder 2, work space 3 and stamp 5 are only illustrated in FIG. 2.

[0055] Furthermore, the apparatus comprises means for providing a multiplicity of powder layers lying on top of one another, said means, as is likewise already known from the prior art, comprising a powder reservoir, which is not illustrated in the figures but disposed directly next to the cylinder 2, and a doctor blade, which is likewise not identifiable. It is evident from FIG. 2 that the cylinder 2 is filled with powder 6. For the purposes of providing a powder layer above the work platform 4 orfrom the second powder layer onwardabove an already additively produced component section 1 situated thereon, powder 6 is conveyed from the powder reservoir by the doctor blade into the work space 3 and spread out smoothly there, each of which is sufficiently well known.

[0056] In order to obtain a component, each of the powder layers provided above one another is selectively fused by means of a laser beam 7 in accordance with a specified component geometry. The laser beam 7 is provided by a laser beam device 8, only illustrated in FIG. 1, of the apparatus and said laser beam is displaced over the powder layer in accordance with the specified geometry by means of a scanning device 9.

[0057] Moreover, the apparatus comprises means for inductively heating the work platform 4 or a component section 1 already constructed thereon, said means being provided by an induction coil 10 in the present case. With the aid of the coil 10, eddy currents are induced in the work platform 4 and/or in a component section 1 already produced thereon during operation and said work platform and/or component section is inductively heated during a production procedure. In particular, the formation of hot cracks is avoided or reduced by the additional inductive heating and it is also possible to process materials that can only be welded poorly. A nickel base substance is used in the illustrated exemplary embodiment.

[0058] Furthermore, capturing means are provided, which are embodied to use measurement technology to capture the temperature distribution on the surface of the work platform 4 or on a component section 1 already constructed thereover or on the surface of a provided powder layer. In the illustrated exemplary embodiment, the capturing means are provided by a thermal imaging camera 11, only identifiable in FIG. 1, of the apparatus, which views in the direction of the work platform 4 or a component section 1 already constructed thereon from above (cf. FIG. 1).

[0059] A further constituent part of the apparatus described here is a central control device 12, which is connected to the stamp 5, the means for providing powder layers, the laser beam device 8, the scanning device 9, the coil 10 and the thermal imaging camera 11 or a further control device, not identifiable in the figures, respectively assigned to these.

[0060] The method according to the invention for the additive manufacture of components can be carried out using the apparatus from FIGS. 1 and 2.

[0061] Here, the temperature distribution on the surface on which the respective powder layer is provided is captured using measurement technology, for each provided powder layer in the present case. In the exemplary embodiment described here, the capture of the temperature distribution using measurement technology is implemented in each case prior to the provision of the layer by virtue of a thermal image of the respective provision surface being recorded using the thermal imaging camera 11. Here, the capture and/or the temporal evaluation of a captured thermal image is advantageously implemented in temporal proximity to the subsequent scanning procedure with the at least one energy beam, more particularly the at least one laser beam. Alternatively, it is also possible for the thermal imaging camera to record continuously and for the thermal images of suitable times to be used in this case.

[0062] A block-by-block procedure is possible, in which a temperature distribution is captured per section, as is a completely (quasi) continuous recording, in which an adaptation is undertaken with each recorded thermal image of the camera for the purposes of regulating the power, for example.

[0063] In the process, the thermal imaging camera 11 records an image of the thermal radiation emitted by the respective surface in the infrared wavelength range, in a manner known per se. The surface temperature images obtained are available in the form of temperature values for each camera pixel and can be used for further processing. By way of example, the temperatures can be presented in the form of false color or grayscale images for the purposes of presenting these to the user.

[0064] The provision surface is the surface of the side of the work platform 4 pointing upward in the figures for the first, lowermost layer and the surface of the side of the respectively already constructed component section 1 pointing upward in FIG. 4 for all further layers.

[0065] The thermal image recorded for each layer in advance is evaluated in each case, wherein, specifically, the temperature gradient is ascertained along specified lines which correspond to subsequent scanning lines of the laser beam 7, along which the laser beam 7 is displaced over the respective layer in order to selectively fuse the latter. In the illustrated exemplary embodiment, the laser beam 7 is displaced over the layers in the x- and y-direction, which is indicated in FIG. 1 by two double-headed arrows that are oriented orthogonally to one another.

[0066] FIG. 3 shows, in exemplary fashion, the ascertained temperature curve 13 along a specified line (here in the x-direction) through a thermal image captured for a component section 1. The y-axis is denoted by T for temperature and the x-axis is denoted by s for the path length along the component. It is evident that there is a significant inhomogeneity in the temperature distribution along the considered line. Specifically, the edge region has a significantly higher temperature than the center, as can be traced back to preferential heating of component edges within the scope of inductive heating.

[0067] According to the invention, the amount of energy introduced by the laser beam 7 during the subsequent scanning procedure is then varied during the displacement along the scanning lines depending on the ascertained temperature gradient, to be precise in such a way that the existing inhomogeneity is reduced or compensated. In the illustrated exemplary embodiment, this is realized by adapting the power of the laser beam 7 during the displacement along the respective scanning line. An exemplary curve of the laser power 14, which compensates the temperature curve 13 illustrated in FIG. 3, can be gathered from FIG. 4. In this graph, the y-axis is denoted by P for the laser power and the x-axis is once again denoted by s for the path length along the component. By comparing FIGS. 3 and 4, it is evident that the laser power is increased where there is a comparatively lower temperature according to the captured temperature distribution and the laser power has been respectively reduced where there is a comparatively higher temperature according to the captured temperature distribution. The case of constant laser power 15 according to the prior art is likewise illustrated in FIG. 4.

[0068] It should be noted that all evaluation and control steps of the described exemplary embodiment are carried out by means of the central control device 12, which is embodied and configured accordingly for the purposes of carrying this out. In the illustrated exemplary embodiment, the control device 12 comprises, inter alia, a computer to this end.

[0069] As a result of the procedure according to the invention, a particularly homogeneous energy introduction and consequently a significant improvement in quality are obtained. The process stability is increased and the demands on the concept of additional heating can be reduced. A further significant advantage consists of faster heating times being able to be achieved, and consequently reduction in the build time and in costs.

[0070] Even though the invention was illustrated more closely and described in detail by the exemplary embodiment, the invention is not restricted by the disclosed examples and other variations can be derived therefrom by a person skilled in the art without departing from the scope of protection of the invention.

[0071] By way of example, the displacement speed of the laser beam 7 can also be adapted as an alternative or in addition to the laser power for the purposes of compensating the inhomogeneous temperature distribution. It is also possible to change the density of the scanning lines. An additional or alternative adaptation of further laser parameters is likewise conceivable so long as this allows a compensation of an existing inhomogeneity on account of the additional inductive heating. Naturally, it is also possible for heating to be performed in any other way as an alternative or in addition to the inductive heating, for example ohmic heating or heating by means of IR beams.

LIST OF REFERENCE SIGNS

[0072] 1 Component section [0073] 2 Cylinder [0074] 3 Work space [0075] 4 Work platform [0076] 5 Stamp [0077] 6 Powder [0078] 7 Laser beam [0079] 8 Laser beam device [0080] 9 Scanning device [0081] 10 Coil [0082] 11 Thermal imaging camera [0083] 12 Central control device