DE102013201629A1 - Generative and layer-wise production of component by e.g. laser, comprises layer-by-layer melting of metal powder located in space of component by laser, where energy required for melting is regulated depending on position of component - Google Patents

Abstract

The method comprises layer-by-layer melting of metal powder located in an installation space (2) of a component (8) by an energy source, where the energy required for melting is detected by a detection device and is regulated depending on the position of the component. The method further comprises carrying out controlled melting of the powder by the source at the positions of the component, in which too little energy is introduced. The parameters of the source depend on the position of the component, where the newly deposited material forms a bond with the already converted material. An independent claim is included for an apparatus for generative and layer-wise production of a component.

Description

The invention relates to a method and a device for the generative and layered production of a component according to the preamble of claim 1 or claim 5.

In the selective laser melting process, the material properties are influenced in particular by the construction process and its process parameters. These include the exposure and gas flow direction, the smoldering produced during melting, the welding spatter also produced during melting, the welding track alignment, the laser stability and the laser positioning accuracy on the material to be processed. The quality of the generatively manufactured components depends on the reproducibility of a stable SLM process.

Such a method is for example from the document EP 1 296 788 B1 known. The temperature distribution in the powder bed is recorded. In particular, the temperature in the molten bath, the cooling temperature and the powder bed temperature are recorded with a camera. Further information on temperature detection can not be found in this document. Commonly known are so-called infrared cameras for detecting temperature distributions. Such IR cameras can measure the actual temperature of the surface of the powder. These IR cameras have the disadvantage that they have a relatively low spatial resolution.

Thus, the object of the present invention is to present a method and a device which stabilizes the SLM process and has a high spatial resolution.

The object is solved by the features of independent claim 1 or by the features of independent claim 5.

The invention relates to a method for the generative and layered production of a component by means of an energy source, which converts a layered material, in particular metal powder, in layers, in particular melts. In this case, the energy introduced into the material by the energy source is detected as a function of the position in the construction space by means of a detection device of at least one component layer. The required energy input is regulated in the material depending on the position.

This is particularly advantageous since no temperature measurement is carried out, but the actual energy that has flowed into the material is detected. It is introduced based on a calibration of gray values, which are generated by the detection device position-dependent, to the adjusted laser energy, a physical unit. In this way, the gray values are assigned to an actual comparative variable occurring in the process - here introduced energy. To represent a temperature value, the temperature would have to be measured with the aid of a second unintentional measuring system at the moment of melting. Since this is very expensive, the set laser energy is used as a reference size, which is available. In addition, the temperature is a time-dependent parameter. With the present method, because of the long exposure time of the detection device, preferably a camera for wavelengths between 370 nm and 1100 nm, at best averaged temperatures can be detected. A calibration to the introduced energy is sufficient for a quantitative statement about the quality of the construction process.

In an advantageous embodiment, the regulation is carried out by means of renewed energy input by means of the energy source at the positions of the component at which too little energy was introduced. This ensures that, in the layered structure of the component in each layer, it is checked whether, in particular in the SLM process, the powdery material, in particular, has received sufficient energy to fuse to the previously produced material layer. In the process, the areas are reworked with energy that has not yet been sufficiently melted or melted.

In a further advantageous embodiment of the invention, powdery (can also be liquid) material is applied to areas that have too little material in the construction of the component layer. In combination or alternatively, powder is applied to the already produced component layer. In this case, it is possible to replenish material specifically for powder defects. Alternatively or in combination, a new powder layer can be applied over the entire installation space, so that the component is completely covered with a new powder layer. This creates areas where little powder has to be melted, and other areas where a lot of powder has to be melted. These different areas are known from the measured values of the detection device, since location-dependent detection in the installation space determines whether (powdery) material is missing.

Accordingly, in a further advantageous embodiment, at least one parameter of the energy source is adjusted in a position-dependent manner such that the newly applied material makes a connection with the already converted material. As an energy source is preferably a laser with a working wavelength of 1050 nm used. In this case, the laser power and / or the feed rate of the laser beam can be adjusted accordingly, so that the newly applied powder melts on powder defects accordingly. Depending on the location, in particular as a function of the measured values of the detection device, the laser parameters are adjusted so that a homogeneous material structure is produced in the component to be produced. This is also the case if too little energy has been introduced into the material.

The invention relates in an alterative to an apparatus for the generative and layered production of a component having a construction space which comprises a material for building the component, an energy source with which an energy beam directed onto the material can be generated and energy can be introduced into the material Control device for controlling the energy source and / or amount of material and a detection device for position-dependent detection of the energy introduced in at least one material layer. The detection device is connected to the control device such that the energy source is regulated according to the required energy input at the corresponding positions in the installation space in the material.

With this device according to the invention a component quality is ensured, which makes a time-consuming and expensive follow-up examination for material defect detection superfluous. Preferably, a laser and / or an electron gun is preferably used for an energy source.

In an advantageous embodiment, the optical axis of the detection device is inclined by an angle α from the solder directed to the construction plane. The angle of inclination is preferably between 5 ° and 25 °. This can be effectively avoided that reflection radiation of the energy source passes into the detection device, but only absorption radiation is detected. Preferably, only the radiation emitted by the incandescent molten bath is detected in the visible wavelength range. For orientation, a so-called black radiator below 850K radiates exclusively in the infrared region, i. Radiation with a wavelength greater than 800nm.

In a further advantageous embodiment, the detection device has an optical filter. For example, this filter can attenuate all wavelengths greater than 800 nm. It can be a bandpass filter that only transmits wavelengths from 400nm to 800nm. In particular, if the wavelengths of the energy source are attenuated, interfering reflection radiation can thus also be suppressed for the measurement.

In a further advantageous embodiment, the installation space is arranged in a protective gas atmosphere, in particular argon. This can be avoided unwanted oxide compounds.

In a further advantageous embodiment of the invention, the detection device comprises a high-resolution detector, in particular a CMOS, sCMOS and / or a CCD sensor for detecting radiation intensity in the wavelength range of 370 nm to 1100 nm. This is particularly advantageous since such as CCD sensors have a higher optical resolution than comparable infrared sensors. This higher optical resolution leads to a higher spatial resolution in the installation space, so that the corresponding parameters can be regulated in a more targeted manner.

Further advantageous embodiments can be taken from the following detailed description and from the subclaims. With reference to the schematic drawing at least one embodiment of the invention will be described in detail. Showing:

1 a page presentation of a SLM system;

2 a plan view of the space as a measured value of the detection device in the absence of powder;

3 a plan view of the space as a measured value of the detection device with lack of energy; and

4 a section through the already melted material in the various stages of manufacture and embodiments.

The 1 shows a page display of a SLM system 1 with a space 2 and an optical device 3 , The installation space 2 is through a protective chamber 4 covered. In the lower part of the installation space 2 is the three-part construction area 5 arranged. In the right area is the powder supply 6 with a in the z-direction (vertically) displaceable Pulvervorrattisch 7 arranged. The powder supply 6 is through the vertical right wall 11 and the vertically extending right medial wall 12 limited. In the middle area of the installation space 2 becomes the component 8th produced. The component 8th is on a preferably horizontally arranged platform 9 constructed on a likewise preferably horizontally arranged platform table 10 is attached. The platform table 10 is by a vertical running left middle wall 13 and the right middle wall 12 limited. In the left area of the installation space 2 is the collection container 15 with a preferably vertically displaceable Residual powder table 16 arranged by a left wall 14 and the left middle wall 13 is limited.

In the lateral area of the installation space 2 in the wall of the shelter 4 Both gas connections are on the left and right side 17 and 18 intended. In this embodiment, the protective gas inlet 17 on the left side and the protective gas outlet 18 arranged on the right side, so that the flow of the protective gas runs from left to right, as indicated by the arrows 20 indicated. Any flow direction is conceivable. Thus, the protective gas flow can be perpendicular to the plane of the drawing.

Now, preferably metal powder on the semi-finished component 8th are applied, so the powder storage table 7 raised vertically by a certain distance. Accordingly, the Bauplattformtisch 10 driven down a certain way. The amount of the two ways can be identical, but not necessarily. The one in the middle of the 1 pictured squeegee 21 is near the right wall and goes from right to left. This pushes the squeegee 21 a powder mountain 22 in front of him. On the left side of the installation space 2 arrived, the excess powder falls into the container 15 , The powder application can also from above, z. B. via nozzles.

In the upper area of the installation space 2 is the optical device 3 arranged. This optical device 3 includes the detection device 31 (optical camera), control device 32 and the energy source 33 (here a laser). Here is the measurement output 34 the optical camera 31 to the control input 35 (wired here) connected. The control outputs 36 and 37 (here only 2 Outputs indicated) of the control device 32 are at the laser 33 (wired) connected. The detection device 31 or the optical axis 37 is not perpendicular to the building level 35 , This vertical or the solder is denoted by the reference numeral 36 played. The optical axis 37 is preferably between 15 ° and 20 ° out of the order 36 inclined. This avoids that the laser beam striking the material 38 is reflected in the detection device and thus causes an increased background noise in the measured values of the detection device.

After fresh metal powder over the semi-finished component 8th was applied, the laser beam hits 38 at the point 48 and melts the metal powder there. During melting, the metal glows and this radiation, preferably in the optical range, is emitted by the detection device 31 detected. The laser 33 becomes according to the 3D structure of the component to be manufactured via the control device 32 guided. Has the laser 33 processed the corresponding points, so arise in the detection device 31 then the in the 2 and 3 shown pictures.

The 2 and 3 give a top view on the construction level 35 from the perspective of the detection device 31 , Dark spots indicate areas that have not been made to glow, and white spots indicate areas that have been sufficiently annealed, ie. sufficient energy was introduced. Thus dark spots are cold areas and bright spots are warm areas. During exposure by the laser beam 38 can the detection device 31 stay on receipt for the entire exposure time. However, these are in the 2 and 3 imaged images preferably composed of smaller frames. This will be through the space 2 flying and glowing metal particles hidden, since only the area in which the laser beam is detected 38 actually works. Exposure times are typically between 1ms and 5000ms. Before the detection device 31 can be an optical filter 71 be arranged, which attenuates in particular the reflection radiation. This can be a filter that the wavelength of the energy source 33 attenuates. Also, an excessive energy input can be detected. With the invention, for example, conclusions about binding errors are possible.

The layer thickness d is exclusively via the z-positioning of the platform table 10 Are defined. By slumping the powder or uneven distribution of the powder in the powder supply 6 the amount of powder applied can be influenced. This is for example in the 2 played. It is a section of a plan view of the component 8th played. It is a dark area 41 and a bright area 42 recognizable. The dark area 41 indicates the area where no metal powder was applied. The bright area 42 indicates the area where sufficient metal powder has been applied. In this bright area 42 is a line-shaped dark area 43 recognizable. This is caused by the fact that, for example, a welding splash from the squeegee 21 entrained during powder application and has accordingly buried in the metal powder layer and has taken along the metal powder, so that at this point 43 too little powder was applied.

The background to this distribution of brightness is that surfaces which are regularly coated with powder (light area 42 ) reach a higher temperature and thus emit more energy than already solidified layers (dark area 41 ). This effect is enhanced by the different heat conduction properties between powder and a solid, which is higher in the solid than in the powder. Thus, the heat stored in the powder can flow off worse.

Furthermore, in 2 recognizable that the surface of the component 8th several tracks 44 having. These run in the 2 essentially horizontally and in the 3 essentially vertical. The laser beam 38 is typically alternating, such as in a serpentine line 46 guided and gives these tracks 44 again. When overlapping the webs 44 arise these railway lines 47 ,

In the 3 is the leading component 8th recognizable (bright area). The component 8th is completely surrounded by powder (another dark area 50 ). The component 8th has 3 openings 51 . 52 and 53 on, which are also dark in this representation, since the powder was not solidified at this point. Within the tracks are partially dark stripes 56 and 58 recognizable. There are also any gray tones conceivable that reflect the different energy input. However, this is not displayed here in the black and white stick figure. According to the invention, the control unit can now 32 after the evaluation of the measured values acquired by the detection device (as in FIGS 2 and 3 reproduced) the laser beam 38 specifically to the poorly or not at all exposed bodies 56 and 58 be steered to subsequently melt the material correctly according to the specifications, so that the desired material properties are met.

In the 4A to F, the different production stages of the invention can be found in the absence of powder. In 4A is a first solidified layer n - 1 with a thickness d to see. It became powder 61 applied, but as faulty as in 2 was reproduced. In the next step (see 4B ) is this incorrectly applied powder 61 with the help of the laser 33 solidified as layer n.

In a first embodiment, it is only there that the subsequently applied powder can be applied 62 be applied to only the missing places. The laser beam 38 solidifies the subsequently applied powder 62 to the layer n '.

In a second embodiment (in combination or alternatively), over the component 8th an additional powder 63 applied (see 4E ). It can be seen that in the left area 64 less powder 63 was applied as in the right area 65 , Due to the shades of gray from the representation of the 2 and 3 Depending on the location, the laser power P and / or the laser beam feed speed is changed such that in the left area 64 less energy is introduced into the material than in the right area 65 , The introduced energy is regulated in such a way that the new layer n + 1 in the left area melts with the underlying layer n and melts on the right with the underlying layer n - 1, so that a substantially homogenous material structure results.

LIST OF REFERENCE NUMBERS

1

 SLM system

2

 space

3

 optical device

4

 protective chamber

5

 construction industry

6

 powder storage

7

 Powder storage table

8th

 component

9

 platform

10

 platform table

11

 right wall

12

 right middle wall

13

 left middle wall

14

 left wall

15

 Collection container for residual powder

16

 Residual powder table

17

 Inert gas inlet

18

 Schutzgasauslass

20

 Arrows (for the flow direction)

21

 doctor

22

 powder mountain

31

 Detection device (optical camera)

32

 control device

33

 Energy source (laser)

34

 Measuring output of detection device

35

 building plane

36

 Lot on construction level

37

 optical axis of the detection device

41

 dark area

42

 bright area

44

 train

46

 wavy line

47

 line

50

 more dark area

51, 52, 53

 openings

61

 incorrectly applied powders

62

 subsequently applied powder

63

 additionally applied powder

64

 left area

65

 right area

71

 optical filter

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• EP 1296788 B1 [0003]

Claims (10)

Method for the generative and layered production of a component ( 8th ) by means of an energy source ( 33 ), one in a space ( 2 ) ( 6 ), in particular metal powder, converted in layers, in particular melts, wherein the material in the material by the energy source ( 33 ) introduced energy as a function of the position in the installation space by means of a detection device ( 31 ) is detected by at least one component layer (n-1, n, n + 1), characterized in that the required energy input into the material ( 6 ) is regulated depending on the position. A method according to claim 1, characterized in that the regulation by means of renewed energy input by means of the energy source ( 33 ) at the positions of the component ( 8th ) takes place at which too little energy was introduced. Method according to at least one of the preceding claims, characterized in that the control by means of application of material ( 61 . 62 . 63 ) to areas that have too little material in the construction of the device layer (s), and / or on the already generated component layer (n - 1). Method according to at least one of the preceding claims, characterized in that the parameters of the energy source ( 33 ) are adjusted depending on the position such that the newly applied material ( 61 . 62 . 63 ) enters into a connection with the already converted material. Device for generative and layered production of a component comprising: - a construction space ( 2 ), a material for building the component ( 8th ) having; - an energy source ( 33 ), with the one on the material ( 61 . 62 . 63 ) directed energy beam ( 38 ) and energy in the material ( 6 ) can be introduced; A control device ( 32 ) for controlling the energy source and / or material quantity and - a detection device ( 31 ) for the position-dependent detection of the energy introduced in at least one material layer, characterized in that the detection device ( 31 ) to the control device ( 32 ) is connected, that the energy source ( 33 ) according to the required energy input at the corresponding positions in the installation space ( 2 ) is regulated in the material. Apparatus according to claim 5, characterized in that the detection device ( 31 ) by an angle (α) from the plane ( 35 ) directed perpendicular, which is in particular between 5 ° and 25 °. Device according to at least one of claims 5 and 6, characterized in that the detection device comprises an optical filter ( 71 ), in particular the radiation in the wavelength range of the energy source ( 31 ), dampens. Device according to at least one of claims 5 to 7, characterized in that the space ( 2 ) is arranged in a protective gas atmosphere, in particular argon. Device according to at least one of claims 5 to 8, characterized in that the energy source ( 33 ) is a laser, in particular with a wavelength of around 1050 μm, and / or an electron source. Device according to at least one of claims 5 to 9, characterized in that the detection device ( 31 ) comprises a high-resolution detector, in particular a CMOS, sCMOS and / or a CCD sensor for detecting radiation intensity in the wavelength range from 370 nm to 1100 nm.

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