EP3826824A1

EP3826824A1 - Additive production device and associated additive production method

Info

Publication number: EP3826824A1
Application number: EP19755339.9A
Authority: EP
Inventors: Stefan Paternoster; Albert Fruth
Original assignee: EOS GmbH
Current assignee: EOS GmbH
Priority date: 2018-08-14
Filing date: 2019-08-13
Publication date: 2021-06-02
Also published as: WO2020035496A1; DE102018213675A1; CN112703102B; CN112703102A; US20210308940A1

Abstract

The invention relates to an additive production device for producing a three-dimensional object, comprising a layer application device (16) for applying a building material layer to layer, an energy input device (20) which comprises a carbon monoxide laser (21) and a radiation supply device for supplying laser radiation of the carbon monoxide laser to points in each layer which are associated with the cross-section of the object in said layer, and a laser power modification device (27) which, in the event of an increase in laser power, is suitable to cause an increase in the power impinging on the building material per unit of area within a period of time, which is less than 300 μs and/or greater than 50 ns, and/or, in the event of a reduction in laser power, to cause a drop in the power impinging on the building material per unit of area within a period of time, which is less than 100 μs and/or greater than 100 ns.

Description

Additive manufacturing device and associated additive manufacturing process

The invention relates to an additive manufacturing device, an associated additive manufacturing method and a molded body produced by means of the same

Additive manufacturing devices and associated processes (also referred to as “additive manufacturing”) are generally characterized in that objects are produced layer by layer in them by solidifying an informal construction material. The solidification can be brought about, for example, by supplying thermal energy to the building material by irradiating it with electromagnetic radiation or particle radiation (e.g. laser sintering or laser melting or electron beam melting). For example, in laser sintering or laser melting, the area of incidence of a laser beam on a layer of the build-up material is moved over those points of the layer that correspond to the object cross section of the object to be produced in this layer.

If a plastic powder (polymer powder) is selected as the building material, the building material is usually solidified by irradiation with a CO2 laser. The latter emits radiation with a wavelength of 10.6 pm and is used in particular because most polymer materials absorb radiation with a wavelength of 10.6 pm well. Since the focus size of the radiation on the building material depends on the wavelength, the greater the detail resolution can be achieved in the objects produced, the lower the wavelength of the radiation used for solidification. Because of the poor absorption of shorter wavelengths than 10.6 pm by polymer materials, DE 199 18 981 A1 proposes to mix the building material with an absorber that absorbs laser radiation with a wavelength of 500 to 1500 nm, so that an emission in this wavelength range is also emitted Lasers, for example an Nd-YAG or an Nd-YLF laser can be used and a better detail resolution can be achieved.

However, the use of absorber additives has a number of disadvantages. On the one hand, the process costs increase due to the material costs of the absorber additives and the requirement of homogeneous mixing of the absorber additives with the building material or the application of the absorber additives to a layer of the building material. Furthermore, the process window shrinks, i.e. the available temperature range for stable process control. Furthermore, the process control is more difficult because inhomogeneities in the absorber quantity can lead to inhomogeneities in the manufactured object or its surface. After all, it is more difficult to obtain objects with a desired color: a dark absorber, such as Soot leads to dark objects that can only be recolored with increased effort, e.g. if bright objects are desired where the dark color does not shimmer through.

The object of the present invention is therefore to provide a laser-based additive manufacturing device and an associated additive manufacturing method, by means of which objects with higher detail resolution can be produced in an additive manner without additional disadvantages.

The object is achieved by an additive manufacturing device according to claim 1, an additive manufacturing method according to claim 8 and a molded body according to claim 14. Further developments of the invention are claimed in the dependent claims. sprucht. In particular, a device according to the invention can also be further developed by the features of the methods according to the invention shown below or in the dependent claims and vice versa. Furthermore, the features described in connection with one device can also be used to develop another device according to the invention, even if this is not explicitly stated.

An additive manufacturing device according to the invention for manufacturing a three-dimensional object has:

a layer application device for applying a building material layer by layer,

an energy input device, which

a carbon monoxide laser, and

has a radiation feed device for feeding laser radiation of the carbon monoxide laser to locations in each layer which are assigned to the cross section of the object in this layer,

and

a laser power modification device which is suitable for causing an increase in the laser power to bring about an increase in the power per unit area impinging on the building material within a period of time which is less than 300 ps and / or greater than 50 ns, and / or with a reduction cause the laser power to drop the power per unit area impinging on the building material within a period of time which is less than 100 ps and / or greater than 100 ns.

In additive manufacturing devices and methods to which the present invention relates, energy in the form of laser radiation is selectively supplied to a layer of the building material. The radiation strikes the building material in a working plane, which is generally a plane in which the upper side of the layer facing the energy input device lies. The material heats up as a result of the energy supplied, as a result of which the building material is sintered or melted. It should be noted at this point that not only one object, but also several objects can be produced simultaneously using an additive manufacturing device. If the present application refers to the production of an object, then it goes without saying that the respective description can also be applied in the same way to additive production methods and devices in which a plurality of objects are produced at the same time.

There are no restrictions with regard to the configuration of the layer application device in the additive manufacturing device according to the invention. Any layer application device known in the field of additive manufacturing, which is capable of building material in layers, i.e. Layer-by-layer application can be part of the additive manufacturing device. The layer application device only has to be suitable for applying an informal building material, in particular a powder, often with a stripping device ensuring a flat surface of an applied layer and thus a constant distance between the energy input device and the building material.

In particular, the layer application device is able to handle a polymer-containing building material, that is to say in particular a plastic powder or a powder that has a plastic portion that is to be melted by the energy supply.

The carbon monoxide laser can be a commercially available laser. The radiation emitted by a carbon monoxide laser is usually in the range between 4 and 8 pm, for example between 5 and 6 pm. The basic structure of the radiation supply devices that can be used can be the same as those used in the area of additive manufacturing when using CO2 lasers. As a rule, a radiation supply device contains a beam deflection device, by means of which the laser radiation is directed onto a layer of the building material. The laser power modification device according to the invention is distinguished by the fact that, with appropriate control, it is able to change the laser power supplied to the building material within a short period of time, that is to say in particular the power impinging on the building material per unit area. The time specified for a power increase relates to the difference between the times at which the existing laser power is increased by 10% or 90% of the power difference amount. Here, the power difference amount relates to the difference between the laser power per unit area supplied to the building material after the power increase and the laser power per unit area supplied to the building material before the power increase. In the same way, the time specified for a power reduction relates to the difference between the times at which the existing laser power is reduced by 10% or 90% of the power difference amount. Here, the power difference amount relates to the difference between the laser power per unit area supplied to the building material after the power reduction and the laser power per unit area supplied to the building material before the power reduction.

A continuous wave laser (cw laser) is preferably used in the present invention. In other words, there is preferably no Q-switching of the laser resonator. The advantage of continuous wave lasers is that they have narrow lines, which may result in better absorption in the material.

It should be emphasized in this context that the laser power modification device is arranged in the beam path behind the carbon monoxide laser, in other words, the laser power modification device is not part of the carbon monoxide laser, but rather modifies the power of the laser radiation only after it has left the carbon monoxide laser. A laser power modification device is therefore expressly not to be understood as a control device of the carbon monoxide laser. Rather, it becomes possible by means of the laser power modification device for a rapid increase and decrease in the radiation intensity when increasing and to reduce the radiant power supply to the building material. So this is not about pulse rise or fall times of a pulsed laser.

It was found that the radiation emitted by a carbon monoxide laser from polymer materials, for example polyamide, is absorbed very well, so that the use of absorber materials can be dispensed with. At the same time, due to the reduced wavelengths compared to the carbon dioxide laser, better detail resolution can be achieved. As a result of the reduced beam focus, it is also possible to achieve better surfaces of the objects produced, in particular a lower surface roughness.

Carbon monoxide lasers usually cannot be switched on and off as quickly as carbon dioxide lasers. As a result of the laser power modification device provided according to the invention, however, the carbon monoxide laser can be switched at the same speed or even significantly higher speed than a carbon dioxide laser. Since, as a rule, the laser beam has to be switched on and off very often during the selective solidification of a build material layer, it is important for a fast production of objects by means of additive production if, according to the invention, no speed losses during the production process have to be accepted and nevertheless, the advantages of using short-wave radiation can be exploited.

The laser power modification device is preferably an acousto-optical or electro-optical modulator.

The modulators mentioned are particularly suitable for effecting rapid switching processes, in particular rapid switching or changing of the laser radiation supplied to the building material.

It is further preferred that the laser radiation penetrating the laser power modification device in the zero order is fed to the locations in each layer which are assigned to the cross section of the object in this layer in order to solidify the building material. In this mode of operation of the acousto-optical or electro-optical modulator, there is no beam deflection of the laser light penetrating the modulator, which is to be supplied to the building material. This eliminates errors that can be caused by changes in the deflection angle and simplifies the adjustment. When the radiation supply is switched off, energy is essentially withdrawn from the zero order into the higher orders.

As the inventors have been able to determine, the residual light which is still present when the radiation supply is switched off in the zero order can be tolerated, even if the building material is a polymer-containing building material. If a polymer-containing build material is used in the additive manufacturing of objects, the build material is normally heated to a working temperature just below the melting temperature by means of radiant heating. The laser radiation then only supplies the missing residual energy for melting the material. Therefore, although one could assume that existing residual light leads to an unintentional melting of the building material, it has been shown that such an unintentional melting can be avoided when using polymer-containing building material, if either it is ensured that the “switched off” laser beam is not too long is directed to the same place of the building material or the working temperature is slightly lowered. When using metal-based building material, in particular steel powder, the available residual light is not critical, since in these cases a considerable percentage of the energy required for melting is supplied by the laser radiation, similar to laser processing.

Further preferably, in the additive manufacturing device, the radiation supply device has a deflection device which is suitable for directing and / or directing laser radiation from the carbon monoxide laser to locations in each layer which are assigned to the cross section of the object in this layer

a focusing device which is suitable for focusing laser radiation from the carbon monoxide laser onto the surface of a layer of building material. There is one characteristic dimension, in particular an aperture size, of the deflection and / or focusing device, less than or equal to about 50 mm, preferably less than or equal to about 20 mm, particularly preferably less than or equal to about 10 mm, and / or greater than or equal to 5 mm.

As already mentioned, as a result of the reduced wavelength compared to the CO2 laser, a smaller focus diameter can be achieved. This means that an aperture size of the radiation feed device can also be selected to be smaller. This in turn means that the dimensions of the optical elements, for example the rotating mirror in a beam deflection device, can be smaller. For a beam deflection device, this means in concrete terms that due to the smaller dimensions of the rotating mirrors, their inertial mass is also lower, which results in a higher acceleration during rotating movements. In the event of changes in the movement of a laser beam used for solidification over the building material, the finite acceleration time in reality due to the inert mass of the rotating mirror causes an offset between the current position of the beam on the building material, referred to as drag delay (sometimes also tracking error) and the intended position. This behavior is particularly evident at the beginning and end of scan lines or hatch lines. Due to the higher acceleration of the rotary mirrors during rotary movements due to the lower inertial mass, the drag delay can advantageously be kept lower. Since, in addition, switching processes for the laser radiation can also take place quickly, the laser power to be entered per unit area can also be adapted to the drag delay in a more precise manner. In particular, the imaging accuracy (shape accuracy) increases for a given scanning speed. Particularly in the case of additive manufacturing devices, the construction according to the invention with the laser power modification device described can therefore be advantageous. In applications in which the workpiece is moved, such as laser cutting or drilling holes with laser radiation, the workpiece carrier and workpiece have such a large mass that accelerations that are not similar to those achieved when using a galvanometer scanner-based deflection device can be achieved The additive manufacturing device preferably has a focusing device which is suitable for a focus diameter of less than or equal to 500 gm, preferably less than or equal to 300 gm, more preferably less than or equal to 250 gm and / or greater than or equal to 80 gm, more preferably greater than or equal to 100 gm, more preferably greater than or equal to 150 gm on the surface of a layer of building material.

In an additive manufacturing method using such an additive manufacturing device, a high resolution of geometric details of the objects produced is achieved due to the small focus diameter. If a deflection and / or focusing device with a small aperture size is used, a high level of detail is achieved, in particular, despite the lag that occurs. Assuming a Gaussian beam profile, a focus diameter can be defined as the mean or maximum diameter of the range within which the beam power is above the beam power maximum divided by e ² , where e is Euler's number.

With the additive manufacturing device, the deflection device is furthermore preferably suitable for moving the laser beam focus over the surface of the building material at a speed that is greater than or equal to 2 m / s and / or less than or equal to 50 m / s, preferably greater than or is 5 m / s and / or less than or equal to 30 m / s, more preferably greater than or equal to 8 m / s and / or less than or equal to 25 m / s.

In an additive manufacturing method according to the invention using such an additive manufacturing device, due to a small aperture size or characteristic dimension of the deflection and / or focusing device, the area of incidence of the laser radiation on the building material is moved at a high speed in comparison to the prior art. Nevertheless, due to the wavelength of the radiation, sufficient energy is introduced to cause the building material to solidify. Objects are thus produced within a shorter period of time in comparison to the prior art, without having to accept losses in quality, in particular in the resolution of details. For the specified values for the speed, it was assumed that the distance between the Deflection device or the rotating mirror and the surface of the build material layer to be selectively strengthened is approximately 50 cm.

In the additive manufacturing device, the laser beam focus can preferably be in mutually parallel hatching lines with a mutual spacing of less than 0.18 mm, preferably less than 0.16 mm, more preferably less than 0.14 mm and / or more than 0.05 mm the surface of the building material is moved and / or a beam offset of less than 0.18 mm, preferably less than 0.16 mm, more preferably less than 0.14 mm, is set.

In an additive manufacturing method using such an additive manufacturing device, as a result of the use of laser radiation with a shorter wavelength, a smaller diameter of the area of incidence of the laser radiation on the building material layer is achieved compared to the use of a CO 2 laser. As a result, the mutual distances between the hatching lines are also chosen to be smaller when scanning the building material by moving the laser beam along mutually parallel scanning lines (hatching lines). This results in a more homogeneous hardening, so that higher quality components are obtained. The term "beam offset" is an English-language term common in the field of additive manufacturing, which specifies the beam offset set on the contour of an object cross section. This beam offset, generally perpendicular to the contour, ensures that when the contour is scanned on the construction material, despite a finite diameter of the radiation impingement area, the outer dimension specified in the model data of the object to be produced is realized as precisely as possible on the object being manufactured.

In an additive manufacturing method according to the invention for producing a three-dimensional object, a building material is applied layer by layer and by means of an energy input device which has a carbon monoxide laser and a radiation supply device, laser radiation of the carbon monoxide laser by means of the radiation supply device places in each layer which corresponds to the cross section of the Object assigned in this layer are supplied. Furthermore, When the laser power is increased, the power output modification device causes an increase in the power per unit area impinging on the building material within a period of time which is less than 300 ps and / or greater than 50 ns, and / or if the laser power is reduced, a drop in the amount impinging on the building material Performance per unit area within a period less than 300 ps and / or greater than 50 ns.

The additive manufacturing method according to the invention achieves the same advantages that result from using the additive manufacturing device according to the invention.

In the additive manufacturing method according to the invention, the building material is preferably essentially absorber-free. The term "absorber-free" expresses the fact that essentially no materials suitable for increasing the absorption of the laser radiation are added to the building material. In particular, the targeted use of auxiliaries to increase the absorption of the laser radiation is completely dispensed with. On the one hand, this refers to the fact that the build material is not mixed with absorber additives, and on the other hand, no absorber is applied to a build material layer before it is solidified. As already mentioned, an additive manufacturing process is easier if the use of absorber auxiliaries is dispensed with. In addition, there are fewer restrictions on the color of the objects, since bright objects in particular are easily available.

The additive manufacturing method according to the invention and the additive manufacturing device according to the invention bring advantages in all additive manufacturing processes in which a construction material is used which absorbs the radiation from the carbon monoxide laser well. However, the building material preferably contains a polymer, preferably in the form of a polymer powder, and / or coated sand and / or a ceramic material, preferably in the form of a ceramic powder. It has been shown that polymers, in particular PA11 and PA12, absorb the radiation from a carbon monoxide laser to a high degree. The inventors have no previous Twists of a carbon monoxide laser for melting polymers, in particular in the field of additive manufacturing, are known.

The building material further preferably comprises a polymer-containing material and in particular contains a polyamide, polypropylene (PP), polyetherimide, polycarbonate, polyphenylsulfone, polyphenyloxide, polyether sulfone, acrylonitrile-butadiene-styrene copolymer, polyacrylate, polyester, polyurethane, polyimide, polyamideimide, polyolefin , Polystyrene, polyphenyl sulfide, polyvinylidene fluoride, polyamide elastomer, polyether retherketone (PEEK) or polyaryl ether ketone (PAEK).

The powdery building material can contain, for example, at least one of the polymers selected from the group formed from the following polymers: polyetherimides, polycarbonates, polyphenylsulfones, polyphenyloxides, polyethersulfones, acrylonitrile-butadiene-styrene copolymers, polyacrylates, polyesters , Polyamides, polyaryl ether ketones, polyethers, polyurethanes, polyimides, polyamideimides, polyolefins, polystyrenes, polyphenyl sulfides, polyvinylidene fluorides, polyamide elastomers such as polyether block amides and copolymers which contain at least two different monomer units of the abovementioned polymers. Suitable polyester polymers or copolymers can be selected from the group consisting of polyalkylene terephthalates (e.g. PET, PBT) and their copolymers. Suitable polyolefin polymers or copolymers can be selected from the group consisting of polyethylene and polypropylene. Suitable polystyrene polymers or copolymers can be selected from the group consisting of syndiotactic and isotactic polystyrenes. The powdery building material can additionally or alternatively contain at least one polyblend based on at least two of the aforementioned polymers and copolymers. With the plastic as a matrix, additives, e.g. Free-flowing aids, fillers, pigments, etc. may be present, but preferably no absorber additives.

More preferably, an area solidified in the area of incidence of the laser radiation on the building material layer has a dimension in the layer plane of less than about 300 gm, preferably less than about 250 mhi, particularly preferably less than about 200 gm.

As a result of the use of laser radiation with a shorter wavelength, in comparison to the use of a C02 laser with the same aperture size, it is possible to achieve a smaller diameter for the area of incidence of the laser radiation on the build material layer. As a result, details with smaller dimensions can be realized using additive manufacturing than would be the case if a C02 laser were used

The layers of the building material are preferably applied with a thickness of less than 80 mhh, preferably less than 60 gm, more preferably less than 50 gm and / or a thickness of 10 gm or more, more preferably 25 gm or more.

As a result of the use of laser radiation with a shorter wavelength, a smaller aperture size or characteristic dimension can be used in the deflection and / or focusing device than in the prior art. In particular as a result of the smaller size and the resulting mass of galvanometer mirrors used as deflection devices, the area of incidence of the laser radiation on the building material can therefore be moved at a higher speed than in the prior art. Objects can thus be produced within a shorter period of time compared to the prior art. This is used to obtain objects with a better resolution of details perpendicular to the building material layers. For this purpose, building material layers of a smaller thickness are applied or solidified. Although this increases the total number of building material layers to be applied and solidified for the production of the object, the production time remains within the limits due to the higher travel speed of the radiation impingement area.

A molded body which, by means of an additive manufacturing process according to the invention, is made from a building material which is essentially absorber-free, in particular soot-free was produced, has at least one detail dimension, in particular a wall thickness, which is less than or equal to 150 gm and / or greater than or equal to 50 gm, preferably greater than or equal to 100 gm.

A molded body produced by an additive manufacturing method according to the invention can have details of a small dimension, although the use of absorber additives has been dispensed with for the production.

The shaped body, in particular made of polyamide, polypropylene (PP), polyetherimide, polycarbonate, polyphenylsulfone, polyphenyloxide, polyether sulfone, acrylonitrile-butadiene-styrene copolymer, polyacrylate, polyester, polyurethane, polyimide, polyamideimide, polyolefin, polystyrene, polyphenylsulfide, Polyvinylidene fluoride, polyamide elastomer, polyether ether ketone (PEEK) or polyaryl ether ketone (PAEK), less than 0.01 wt .-% absorber material.

As already mentioned above, with the additive manufacturing method according to the invention in particular molded articles made of a plastic-containing material can be obtained. The absence of absorber additives can also be seen in the molded articles themselves, which, for example, are free from soot and can therefore be obtained in a lighter color without the need for subsequent coloring.

Further features and advantages of the invention result from the description of exemplary embodiments with reference to the accompanying drawings.

1 shows a schematic view, partly in section, of an exemplary device for additively producing a three-dimensional object according to the invention.

2 is used to illustrate schematically the use of an acousto-optic modulator used as a laser power modification device in the context of the present invention. To build an object 2, a laser sintering or melting device 1 shown as an example of an additive manufacturing device contains a process chamber or construction chamber 3 with a chamber wall 4. In the process chamber 3, a construction container 5 with an open top is arranged with a container wall 6. A working level 7 is defined through the upper opening of the building container 5, the area of the working level 7 lying within the opening which can be used to build up the object 2 being referred to as the building area 8.

Arranged in the building container 5 is a carrier 10 which can be moved in a vertical direction V and on which a base plate 11 is attached, which closes the container 5 at the bottom and thus forms the bottom thereof. The base plate 11 may be a plate formed separately from the carrier 10, which is fastened to the carrier 10, or it may be formed integrally with the carrier 10. Depending on the powder and process used, a building platform 12 can also be attached to the base plate 11 as a building base on which the object 2 is built. The object 2 can also be built on the base plate 11 itself, which then serves as a construction document. 1 shows the object 2 to be formed in the container 5 on the building platform 12 below the working plane 7 in an intermediate state with a plurality of solidified layers, surrounded by construction material 13 that has remained unconsolidated.

The laser sintering or melting device 1 further contains a storage container 14 for a building material 15, in this example a powder that can be solidified by electromagnetic radiation, and a coating device 16 movable in a horizontal direction H as a material application device for applying the building material 15 in layers of the construction field 8. Optionally, a heating device, for example a radiation heater 17, can be arranged in the process chamber 3, which serves to heat the applied building material. For example, an infrared radiator can be provided as the radiation heater 17. The exemplary additive manufacturing device 1 also contains an energy input device 20 with a carbon monoxide laser 21, which generates a laser beam 22, which is deflected by a deflection device 23 and by a focusing device. device 24 via a coupling window 25, which is attached to the top of the process chamber 3 in the chamber wall 4, is focused on the working level 7. For example, the laser sold by Coherent under the name "DIAMOND J-3-5 CO Laser" can be used as the carbon monoxide laser.

The deflection device 23 essentially consists of a galvanometer mirror for the deflection in the X direction and the deflection in the Y direction, it being assumed that the working plane 7 expands in the X and Y directions. In particular, there is a laser power modification device 27 in the beam path between the carbon monoxide laser 21 and the deflection device 23, which is an acousto-optic modulator in the present example. Such modulators are sold for example by the company Gooch & Housego PLC in Ilminster UK, for example the model I-MOXX-XC11 B76-P5-GH105 can be controlled with up to 60MFIz.

2 shows in detail the way in which the acousto-optical modulator is used in the present example. The laser beam 22 emitted by the carbon monoxide laser 21 is split in the acousto-optical modulator 27 into a beam 22a and a beam 22b supplied to the deflection device 23. In the present example, beam 22a is the zero order of the diffraction pattern and beam 22b is the first order of the diffraction pattern. Of course, higher orders also occur, but these are not shown for reasons of simpler presentation. It can be seen that in the present example the laser power modification device 27 serves to attenuate the beam 22 emitted by the carbon monoxide laser 21, in order to thus modulate its power. The beam 22a fed to the deflection device 23 runs in the same direction as the beam 22 which is emitted by the carbon monoxide laser 21. Even if fluctuations in the ambient conditions lead to fluctuations in the behavior of the acousto-optical modulator, this has no effect on the direction of the beam supplied to the deflection device 23. By means of the arrangement shown, the power in the beam 22 is essentially directed into the higher orders in order to switch off the beam in order to achieve as little power as possible in the zero order. By controlling the The beam supplied to the deflection device 23 is thus essentially switched off and on by the acousto-optical modulator 27. The residual power that is still available when the device is switched off in the zero order is in the range of a few percent and is tolerable, since it generally cannot cause unintentional solidification of the building material. The presence of residual light from the radiation source used for solidification is known in the prior art and is referred to there as "bleeding".

The laser sintering device 1 also contains a control device 29, via which the individual components of the device 1 are controlled in a coordinated manner in order to carry out the construction process. Alternatively, the control device can also be attached partially or entirely outside the additive manufacturing device. The control device can contain a CPU, the operation of which is controlled by a computer program (software). The computer program can be stored separately from the additive manufacturing device in a storage device, from where it can be loaded (e.g. via a network) into the additive manufacturing device, in particular into the control device.

In operation, the control device 29 lowers the carrier 10 layer by layer, the coater 16 is activated to apply a new powder layer, and the laser power modification device 27, the deflection device 23 and, if appropriate, also the laser 21 and / or the focusing device 24 are activated Solidification of the respective layer at the points corresponding to the respective object by means of the laser by scanning these points with the laser.

In the additive manufacturing device just described by way of example, a manufacturing process takes place in such a way that the control unit 29 processes a control data record. Through the control data set, an energy input device, in the case of the above

Laser sintering or laser melting device, especially the deflection device 23, for each the point in time during the solidification process is given, to which point on the working plane 7 radiation is to be directed.

As mentioned above, instead of the acousto-optical modulator, another optical device can also be used as the laser power modification device, provided that it is able to within a short period of time the laser power supplied to the building material, that is to say in particular the power impinging on the building material per unit area. amend. For example, a correspondingly quickly controllable photoelastic modulator (PEM) or an adequate delay plate (e.g. 1/2 plate) could also be used together with a polarizer.

Claims

claims

1. Additive manufacturing device for manufacturing a three-dimensional object with:

a layer application device (16) for applying a building material layer by layer,

an energy input device (20) which

a carbon monoxide laser (21) and

and

a laser power modification device (27) which is capable of causing an increase in the laser power to increase the power impinging on the building material per unit area within a period of time which is less than 300 ps and / or greater than 50 ns, and / or at Reduction of the laser power to cause a drop in the power per unit area impinging on the building material within a period of time which is less than 100 ps and / or greater than 100 ns.

2. Additive manufacturing device according to claim 1, wherein the laser power modification device (27) is an acousto-optical or electro-optical modulator.

3. Additive manufacturing device according to claim 2, in which the laser power modification device (27) penetrating into the zero order laser radiation is supplied to the locations in each layer, which are assigned to the cross section of the object in this layer, in order to solidify the building material.

4. Additive manufacturing device according to one of the preceding claims, wherein the radiation supply device has a deflection device (23) which is suitable To direct and / or laser radiation of the carbon monoxide laser (21) to locations in each layer which are assigned to the cross section of the object in this layer

a focusing device (24, 25) which is suitable for focusing laser radiation from the carbon monoxide laser onto the surface of a layer of building material, a characteristic dimension, in particular an aperture size, of the

Deflection and / or focusing device, less than or equal to about 50 mm, preferably less than or equal to about 20 mm, particularly preferably less than or equal to about 10 mm, and / or greater than or equal to 5 mm.

5. Additive manufacturing device according to claim 4, which has a focusing device which is suitable for a focus diameter of less than or equal to 500 pm, more preferably less than or equal to 300 pm, more preferably less than or equal to 250 pm and / or greater than or equal to 80 pm, more preferred produce greater than or equal to 100 pm, more preferably greater than or equal to 150 pm on the surface of a layer of building material.

6. Additive manufacturing device according to claim 4 or 5, wherein the deflection device is suitable for moving the laser beam focus at a speed over the surface of the building material which is greater than or equal to 2 m / s and / or less than or equal to 50 m / s , preferably greater than or equal to 5 m / s and / or less than or equal to 30 m / s, more preferably greater than or equal to 8 m / s and / or less than or equal to 25 m / s.

7. Additive manufacturing device according to one of the preceding claims, wherein the laser beam focus in mutually parallel hatching lines with a mutual distance of less than 0.18 mm, preferably less than 0.16 mm, more preferably less than 0.14 mm and / or more than 0.05 mm can be moved over the surface of the building material and / or a beam offset of less than 0.18 mm, preferably less than 0.16 mm, more preferably less than 0.14 mm can be set that can.

8. Additive manufacturing process for producing a three-dimensional object, in which a building material is applied layer by layer and

by means of an energy input device (20), which has a carbon monoxide laser (21) and a radiation supply device, laser radiation of the carbon monoxide laser is supplied by means of the radiation supply device to locations in each layer which are assigned to the cross section of the object in this layer,

and

by means of a laser power modification device (27) when the laser power is increased, the power per unit area impinging on the building material is increased within a period of time which is less than 300 ps and / or greater than 50 ns, and / or when the laser power is reduced Decrease in performance per unit area impinging on the building material within a period of time that is less than 300 ps and / or greater than 50 ns.

9. Additive manufacturing method according to claim 8, wherein the building material is substantially absorber-free.

10. The method according to any one of the preceding claims, wherein the building material contains a polymer, preferably in the form of a polymer powder, and / or coated sand and / or a ceramic material, preferably in the form of a ceramic powder.

11. The method according to any one of the preceding claims, wherein the building material comprises a polymer-containing material and in particular a polyamide, polypropylene (PP), polyetherimide, polycarbonate, polyphenyl sulfone, polyphenyl oxide, polyether sulfone, acrylonitrile-butadiene-styrene copolymer, Contains polyacrylate, polyester, polyurethane, polyimide, polyamideimide, polyolefin, polystyrene, polyphenyl sulfide, polyvinylidene fluoride, polyamide elastomer, polyether ether ketone (PEEK) or polyaryl ether ketone (PAEK).

12. The method according to any one of the preceding claims, wherein a region solidified in the region of impact of the laser radiation on the layer of building material comprises a measurement in the layer plane of less than about 300 pm, preferably less than about 250 mih, particularly preferably less than about 200 pm.

13. The method according to any one of the preceding claims, wherein the layers of the building material with a thickness of less than 80 microns, preferably less than 60 pm, more preferably less than 50 microns and / or a thickness of 10 miti or more, more preferably 25 microns or more.

14. Shaped body, produced by one of the methods according to claims 8 to 13, from a building material which is essentially absorber-free, in particular soot-free, at least one detail dimension, in particular a wall thickness, being less than or equal to 150 pm and / or greater than or equal to 50 miti, preferably greater than or equal to 100 pm.

15. Shaped body according to claim 14, in particular made of polyamide, polypropylene (PP),

Polyetherimide, polycarbonate, polyphenylsulfone, polyphenyloxide, polyethersulfone, acrylonitrile-butadiene-styrene copolymer, polyacrylate, polyester, polyurethane, polyimide, polyamideimide, polyolefin, polystyrene, polyphenylsulfide, polyvinylidene fluoride, polyamide elastomer, polyEK ether (polyetheretherketon) (polyether ether ketone) (polyether ether ketone) ), which has less than 0.01% by weight of absorber material.