Control in generative production

Abstract

Disclosed is a method for generatively producing components by layer-by-layer building from a powder material by selective material bonding of powder particles by a high-energy beam. An eddy current testing is carried out concurrently with the material bonding. Also disclosed is an apparatus which is suitable for carrying out the method.

Claims

1. A method for generatively producing components by layer-by-layer building from a powder material by selective material bonding of powder particles by a high-energy beam, wherein an eddy current testing is carried out concurrently with the material bonding, an eddy current measuring arrangement with at least one coil arrangement that comprises at least one transmitter coil and at least one integrated or separate receiver coil and surrounds the high-energy beam being used for the eddy current testing.

2. The method of claim 1, wherein the material bonding takes place by at least one of welding and sintering.

3. The method of claim 1, wherein the high-energy beam is a laser beam or an electron beam.

4. The method of claim 1, wherein the high-energy beam is passed in a desired pattern over a surface having thereon powder particles to be subjected to material bonding.

5. The method of claim 1, wherein the coil arrangement comprises a differential or multi-differential coil.

6. The method of claim 1, wherein in the eddy current testing, the coil arrangement is passed over the surface of a powder layer.

7. The method of claim 1, wherein one or more measured values of the eddy current testing are used for automatic control of parameters of the layer-by-layer building.

8. The method of claim 1, wherein one or more measured values of the eddy current testing are used for automatic control of parameters of the material bonding.

9. The method of claim 1, wherein one or more measured values of the eddy current testing are used for determining whether and/or how a finishing is carried out.

10. The method of claim 1, wherein measured values of the eddy current testing are filtered by a high-pass filter on the basis of a different speed of movement of the coil arrangement and the high-energy beam.

11. A method for generatively producing components by layer-by-layer building from a powder material by selective material bonding of powder particles by a high-energy beam, wherein an eddy current testing is carried out concurrently with the material bonding, an eddy current measuring arrangement with at least one coil arrangement which comprises at least one transmitter coil and at least one integrated or separate receiver coil being used for the eddy current testing, and wherein a speed of movement of the high-energy beam is different from a speed of movement of the at least one coil arrangement.

12. The method of claim 11, wherein the speed of movement of the high-energy beam is greater than the speed of movement of the at least one coil arrangement.

13. The method of claim 12, wherein measured values of the eddy current testing are filtered by a high-pass filter on the basis of a different speed of movement of the coil arrangement and the high-energy beam.

14. The method of claim 11, wherein measured values of the eddy current testing are filtered by a high-pass filter on the basis of a different speed of movement of the coil arrangement and the high-energy beam.

15. The method of claim 11, wherein the material bonding takes place by at least one of welding and sintering.

16. The method of claim 11, wherein the high-energy beam is a laser beam or an electron beam.

17. The method of claim 11, wherein the coil arrangement comprises a differential or multi-differential coil.

18. The method of claim 11, wherein one or more measured values of the eddy current testing are used for automatic control of parameters of the layer-by-layer building.

19. The method of claim 11, wherein one or more measured values of the eddy current testing are used for automatic control of parameters of the material bonding.

20. The method of claim 11, wherein one or more measured values of the eddy current testing are used for determining whether and/or how a finishing is carried out.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) In the purely schematic accompanying drawings:

(2) FIG. 1 shows a schematic representation of an apparatus according to the invention for the generative production of components by the example of selective laser melting; and

(3) FIG. 2 shows a plan view of a surface of a powder particle layer with a laser beam and a coil arrangement during the application of a layer.

DETAILED DESCRIPTION OF THE PRESENT INVENTION

(4) The particulars shown herein are by way of example and for purposes of illustrative discussion of the embodiments of the present invention only and are presented in the cause of providing what is believed to be the most useful and readily understood description of the principles and conceptual aspects of the present invention. In this regard, no attempt is made to show details of the present invention in more detail than is necessary for the fundamental understanding of the present invention, the description in combination with the drawings making apparent to those of skill in the art how the several forms of the present invention may be embodied in practice.

(5) FIG. 1 shows in a purely schematic representation an apparatus 1 according to the invention, as may be used for example for selective laser melting for the generative production of a component. The apparatus 1 comprises a lifting table 2, on the platform of which there is arranged a semifinished product 3, on which material is deposited layer by layer in order to generate a three-dimensional component. For this purpose, powder 10, which is located above a lifting table 9 in a powder store, is pushed by means of the pusher 8 layer by layer over the semifinished product 3 and subsequently bonded with the already present semifinished product 3 by melting or sintering by the laser beam 13 of a laser 4. The bonding of the powder material in a powder layer with the semifinished product 3 takes place by the laser 4 in a way depending on the desired contour of the component to be produced, so that any desired, three-dimensional forms can be generated. In order to avoid undesired reactions with the ambient atmosphere during the melting or sintering, the process may take place in an enclosed space, which is provided by a housing 11 of the apparatus 1, and moreover an inert gas atmosphere may also be provided, in order for example to avoid oxidation of the powder material during the depositing and the like.

(6) The laser beam 13 moves over the powder layer 14 arranged over the component 3, in order to melt the powder material at the locations at which the component 3 is to be generated layer by layer and to enter into a material bond with the already existing component 3. As an alternative to melting, the powder material may also merely be heated up to the extent that a sintering process takes place.

(7) With a deflecting unit that is not represented any more specifically, the laser beam 13 generated by the beam generating unit 4 is deflected in two directions that are independent of one another in such a way that every location of the surface of the powder particle layer 14 can be reached. In this way it is possible to realize any desired three-dimensional form of the component 3 to be produced.

(8) During the interaction of the laser beam 13 with the powder of the powder layer 14, a coil arrangement 7, with which an eddy current testing can be carried out during the melting or sintering of the powder, is provided around the laser beam 13.

(9) The coil arrangement 7 comprises a transmitter coil and at least one receiver coil, preferably two separate receiver coils (not represented), wherein eddy currents are generated by the transmitter coil in the machining region of the laser beam 7 and the magnetic fields induced by the eddy currents are measured by the receiver coil. The measurement of the magnetic fields generated by the eddy currents allows the state of the material in the machining region of the laser beam 13 to be inferred. This knowledge in turn makes it possible to set the settings and parameters of the apparatus for the generative production of the component in dependence on the eddy current testing. For this purpose, the coil arrangement 7 is connected to an actuating unit 5 of the eddy current measuring arrangement, which on the one hand provides the coil current for the coil arrangement 7 and on the other hand receives the measurement data of the coil arrangement 7. Furthermore, the actuating unit 5 brings about the movement of the coil arrangement 7 together with the laser beam 13, wherein the coil arrangement with a single integrated transmitter and receiver coil or separate transmitter and receiver coils can move at a small distance from the machining surface in parallel above the powder layer 14 in two independent directions. The actuating unit 5 of the eddy current measuring arrangement is connected to a control unit 12, which receives the measurement data of the eddy current testing and, in dependence on these measurement data, generates control data for the laser beam generating device 4 and transmits them to the latter via the control data line 6. In addition, the control unit 12 may also supply the lifting tables 2 and 9 and the pusher 8 with control data, in order for example to influence the arrangement of the powder in the powder layer 14 or the thickness of the powder layer 14 or the like in dependence on the eddy current testing. In this way, the control unit 12 can be used to realize automatic control, with which, by means of eddy current testing using the coil arrangement 7, the state of the layer structure on the component 3 is detected and the parameters for the generative production, such as for example beam power, speed of movement of the beam over the surface of the powder layer 14 or the component 3, thickness of the powder layer 14, size of the focal point of the beam, movement sequence of the laser beam 13 (scanning strategy), possible preheating of the powder layer 14 and/or the component 3, for example by inductive heating and the like, are set in situ.

(10) In addition, the knowledge obtained from the eddy current testing may also be used for finishing a layer, that is to say exposing it with the laser beam 13 for a second time, in order to heal defects established in the eddy current testing.

(11) FIG. 2 shows a plan view of the powder layer 14 during machining with the laser beam 13. As can be seen from FIG. 2, provided around the point of impingement of the laser beam 13 on the powder layer 14 or around the laser beam 13 is a coil arrangement 7, which moves with the laser beam 13 over the surface of the powder layer 14. With the aid of the coil arrangement 7, an eddy current testing can be carried out, as described above, in order to be able to adapt the conditions for the generative growth of the layers during the production of the component 3.

(12) The coil of the coil arrangement 7 may have a diameter of up to 5 cm and be moved at a distance of from 0.1 mm to 1 mm from the surface of the powder layer 14 at a speed in the range from 50 mm per second to 2000 mm per second. The laser beam 13 may be additionally moved within the coil arrangement 7 in relation to the coil arrangement 7, for example by a back and forth movement transversely with respect to the forward movement of the laser beam 13 in the machining direction. Correspondingly, the speed of movement of the laser may be higher than the speed of movement of the coil arrangement 7.

(13) Although the present description refers to the movement of the beam and the coil arrangement in relation to the component or semifinished product, it goes without saying that the relative movement may also be realized by a movement of the semifinished product with respect to the beam and the coil arrangement.

(14) While the present invention has been described with reference to exemplary embodiments, it is understood that the words which have been used herein are words of description and illustration, rather than words of limitation. Changes may be made, within the purview of the appended claims, as presently stated and as amended, without departing from the scope and spirit of the present invention in its aspects. Although the present invention has been described herein with reference to particular means, materials and embodiments, the present invention is not intended to be limited to the particulars disclosed herein; rather, the present invention extends to all functionally equivalent structures, methods and uses, such as are within the scope of the appended claims.