DE202013010698U1 - Apparatus for producing a shaped body by locally remelting or optionally sintering of material powder - Google Patents

Abstract

Apparatus for producing a shaped body by locally remelting or, if appropriate, sintering of material powder into contiguous regions of the shaped body in accordance with geometry description data of the shaped body by energy input by means of radiation (27), in particular laser radiation, in a process space (9) which has a base (11), a ceiling and side walls (72, 74), characterized in that the bottom (11) and / or the ceiling and / or at least one of the side walls (72, 74) process chamber side with a non - stick coating (75) is provided from a non - stick material or are formed or made of such a non-stick material.

Description

The invention relates to a device for producing a shaped article by locally remelting or possibly sintering of material powder to contiguous regions of the shaped body in accordance with Geometriebeschreibungsdaten of the shaped body by energy input by means of radiation, in particular laser radiation, in a process chamber having a bottom, a ceiling and side walls ,

More particularly, this invention relates to the field of selective laser melting and selective laser sintering, and is both procedurally and device-based in technology, such as those disclosed in U.S. Pat. B. in the WO 2010 086327 A1 , in the DE 19905067 A1 , in the DE 10112591 A1 , in the WO 98/24574 A or in the WO 2006 024373 A2 is described.

The technology under consideration here is a means for the production of moldings after the process of selective laser melting (also referred to as "SLM process") or optionally after the process of selective laser sintering. In this case, the realization of the respective shaped body corresponding to three-dimensional CAD data or Geometriebeschreibungsdaten of the shaped body by preferably layered build up of powdered, metallic or ceramic material, wherein successively more powder layers are applied one above the other and each powder layer before applying the next powder layer with a normally focused laser beam is heated in a predetermined area corresponding to a selected cross-sectional area of the molded body. The laser beam is guided in each case in accordance with the CAD cross-sectional data of the selected cross-sectional area of the shaped body or according to data derived therefrom via the respective powder layer. The material powder is applied in the selective laser melting as binder- and flux-free, metallic, ceramic or mixed-metallic / ceramic material powder and heated by the laser beam to melting temperature, the energy of the laser beam and the laser beam guide are chosen so that the material powder in the irradiated area on the powder layer thickness is melted as completely as possible. Over the zone of interaction between the laser beam and the metallic and / or ceramic material powder is usually a protective gas atmosphere, for. As argon atmosphere, maintained. Attempts have also been made to carry out selective laser melting or laser sintering in a vacuum atmosphere.

For details of the structure of a device of the generic type is particularly to the WO 2010 086327 A1 and on the EP 2286982 A1 both of which are incorporated by reference into the disclosure of the present application.

As a powder material, various powder materials come into question, such as steel, titanium, gold and. v. a. m. The powder particle sizes are in the range of a few microns to z. B. 150 microns, although other grain sizes come into question. Such fine powders should be handled in a system that is as closed as possible, containing the process space, which prevents the penetration of potentially harmful powder fine dusts as far as possible. This concerns both the powder feed to the process space and the recovery of residual powder, which remains during the construction process, from the process area. An efficient residual powder recovery system is also useful for economic reasons, since the material powders used are valuable and expensive. Furthermore, it should be prevented that residual powder dust or condensed powder residues pollute the process area. Such contamination could result in that during construction processes with new, in particular other powder materials in the process space, these powder materials are contaminated by such contamination of older residual powder and irregularities in the material composition of the new shaped article occur.

There are already very well-functioning residual powder recovery systems have been developed, which allow suction of powder from the process space in a protective gas atmosphere, the powder can be passed through a sieve and then used again for a building process in a generic device. In this regard is on the EP 1793979 B1 , the EP 2522446 A1 and the DE 20 2010 018 017 U1 directed. Powder recovery systems described therein may also be used in conjunction with the present invention.

In the hitherto known devices for selective laser melting or devices for selective laser sintering, the process spaces have a floor, a ceiling and side walls made of metal, in particular aluminum or stainless steel, wherein windows are normally provided in the ceiling and a front side wall formed as a front door. The window in the ceiling serves to transmit the radiation to remelt the powder and can be used as an optical element, for. B. be formed as a lens. The window in the front door is used for process monitoring from the outside. Furthermore, openings may be made in the process space walls be provided to initiate inert gas, in particular argon, in the process room and deploy out of the process room. Furthermore, powder feed channels can open into walls of the process space, also in the process room floor. In most generic devices, the process room floor has an opening to a building cylinder with a guided therein displaceable piston, which forms a building platform for molded body. The piston is gradually lowered in the structural cylinder to adjust a respective new powder layer to a certain level on the process room floor.

The invention has the object of providing a device of the type mentioned in such a way that it allows a simplified, efficient residual powder recovery from the process space.

To solve this problem, a device with the features of claim 1 is proposed, namely an apparatus for producing a shaped body by locally remelting or optionally sintering of material powder to contiguous areas of the shaped body in accordance with Geometriebeschreibungsdaten of the shaped body by energy input by means of radiation, in particular laser radiation a process space housed in a housing and having a floor, ceiling and side walls, the floor and / or ceiling and / or at least one of the side walls being provided with a non-stick coating or non-stick material is formed or are.

Preferably, the floor and the ceiling and the side walls, so all the process space delimiting areas including any door except windows and openings are provided substantially over the entire surface with the non-stick coating. The lining according to the invention of the process space with a non-stick coating substantially facilitates the handling of the material powder, in particular the collection of residual powder after completion of a shaped body in the process space. On the one hand, during a building process in the process space, powdered powder that has been swirled up or vaporized and condensed powder during the building process does not adhere firmly to the process space walls and can thus be collected much easier than before for recovery.

Usually, the moldings after completion of its construction process on a building platform at the bottom of the process chamber and there is at least partially embedded in residual powder, which was not remelt during the construction process. Depending on the embodiment of the device, this residual powder can be sucked out of the process space by means of a suction device, so that it can be collected and, if necessary, made available for reprocessing for a new construction process. Such as In DE 20 2010 018 017 U1 explained, the suction of the residual powder can take place in a protective gas atmosphere. The suction can be carried out according to a variant by means of a feasible in the process room suction pipe, as shown in the DE 20 2010 018 017 U1 is explained. To loosen the powder z. B. a tuyere or a windpipe be provided in the process space, as also in the DE 20 2010 018 017 U1 is mentioned.

Alternatively, for sucking residual powder and a suction bell be present, which is slipped over a structural cylinder after completion of a shaped body, as z. B. in the EP 2286982 B1 is explained. In this case, suction is carried out via a suction line connected to the suction cup, and gas is introduced into the suction cup via a gas supply line in order to loosen residual powder.

All of these measures can also be taken in the device according to the present invention and they allow a more or less coarse removal of powder from the process space.

Finely dispersed residual powder or residual powder adhering to process space walls can not always be reliably removed with the measures mentioned. In this regard, however, the present invention offers significant advantages. Thus, after a coarse deduction of the residual powder, a device for blowing gas into the process space can be used to whirl or free-blow powder still distributed on the floor or possibly weakly adhering to other walls, so that it is easier to remove from the process space in a suction process. The prerequisite for a good efficiency in this procedure is that the residual dust can easily be blown away from the walls or whirled up from the process room floor. This requirement has been created by the invention by lining the process space with an anti-stick non-stick coating, or alternatively comprising process space walls made of such anti-stick material.

Preferably, the non-stick material is a ceramic material or consists predominantly of ceramic material or mineral material. Ceramic non-stick coatings can be found z. B. also in high-quality cookware, especially frying pans. They offer low friction and hardly adhere to anything. Further advantages are the temperature stability, the scratch resistance and the biocompatibility of a ceramic coating of the process space of a device according to the present invention.

Particular preference is given to using an anti-adhesive layer which is white or at least light-colored on its surface. This has the advantage that most of the powders stand out in high contrast against the light background and thus scattered powder residues in the process area can be detected more easily and thus can be removed faster and more easily. In addition, a bright, especially white-lined process room offers an appealing design. Furthermore, due to the bright walls of the process room is well manageable even with poor lighting.

As a non-stick material is alternatively or additionally polytetrafluoroethylene (PTFE) in question. PTFE-based sealants are also used in cookware, in particular frying pans. They also offer little friction and hardly adhere to anything.

As further non-stick coatings nanostructured layers come into question, which offer the so-called Lotoseffekt and also can hardly adhere to itself and offer little friction.

Preferably, the device according to the invention comprises at least one powder feed channel for supplying material powder to the process space, wherein this powder feed channel is also lined with a non-stick coating of one of said materials inside. Due to its low friction effect, the non-stick coating makes it easier for the powder to flow in the powder feed channel than has hitherto been the case with powder feed ducts made of metal or plastic.

If, according to a further embodiment of the invention, a powder discharge channel is also connected to the process space, it is recommended to also line this powder discharge channel with such a non-stick coating in order to achieve good flowability for the powder.

According to further variants of the invention, components of the device according to the invention installed in the process space are also provided with a non-stick coating at least in some areas, in order to prevent the adhesion of powder thereto or at least to facilitate the free-blowing of powder residues by a gas jet. These components may be a construction cylinder and a piston displaceable therein, which forms a construction platform for the shaped bodies to be produced. In particular, on the opposite surfaces of the construction cylinder and the piston, a non-stick coating may be advantageous to minimize the friction between these surfaces and also to achieve a sealing effect.

The device according to the invention preferably comprises a powder layer preparation device for preparing material powder layers to be provided sequentially on a construction platform for location-selective irradiation, wherein the powder layer preparation device has components in the process space which are at least partially provided with a non-stick coating of a non-stick material and to which a smoothing slide for leveling belongs to the powder layers on the build platform.

Preferably, the device according to the invention on a lock chamber between the process space and the external environment of the device, as z. B. in the EP 1793979 B1 is described, wherein this lock chamber is lined inside on its walls with a non-stick coating.

Generally, it is contemplated in the present invention to include all opaque elements in contact with powder, be it process rooms, powder processing rooms, powder feed / discharge lines, powder suction lines, suction bells, filters, screens, etc., with a respective non-stick coating on theirs with powder to be provided in contact surfaces. This applies in particular also to a powder sieving device for sieving material powder, with a sieve chamber containing a powder sieve, wherein the sieve chamber has on its inside walls or / and the powder sieve a non-stick coating of a non-stick material of the type mentioned or is formed from such a non-stick material or are.

A device for producing a shaped article according to the present invention has proved to be extremely advantageous in terms of clean powder handling in test runs. Even the smallest amounts of residual powder could easily be detected after completion of a building process and the coarse removal of residual powder and removed by stirring and suction with inert gas or possibly air.

Also, mechanical cleaning aids, such as hand brushes or the like. Have been used effectively to collect residual powder from the process room and remove. It has become much easier to clean the process space after a construction process, so that a contamination of any other powder for the next building process can be avoided by residual powder of the previous construction process. A bright, especially white lining of the process room with Non-stick material also has the advantage that it can be very well inspected for the whereabouts of small amounts of residual powder, so that you can remove this residual powder then targeted.

The invention will be explained in more detail below with reference to the figures.

1 shows a perspective view of an embodiment of an SLM device according to the invention in an external view.

2 shows in a rough schematic way a snapshot during the process of irradiation of a last prepared on a construction platform in the process space powder layer.

3 shows in a perspective view of the process space compartment of the device 1 in a largely disassembled state, to give a view into the interior of the process space.

1 shows an example of an SLM device according to the invention, a SLM table device, which z. B. for the production of dental prostheses, jewelry, small machine parts, etc., and in particular for the field of research on processes in selective laser melting (SLM) or possibly in the selective Lasersintrn (SLS) is suitable.

The SLM device 1 has a housing 3 with a process room compartment 5 and a supply compartment 7 on. In the process room compartment 5 is the process room 9 with his process room floor 11 and a built-in platform 13 like this through the viewing window 15 in the front housing wall of the process room compartment 5 can be seen. A stereo microscope 17 can be used to observe the SLM building process. In the opposite side walls 20 of the process room compartment 5 are passage openings 19 provided, which are sealed by a designated Durchgriffs glove (not visible) to the outside. The process room compartment 5 is thus designed as a glove box and allows manual access to components in the process room 9 from the outside. During the building process of a molded article prevails in the process room 9 preferably inert gas atmosphere.

In the supply compartment 7 Among other things, components for the protective gas supply, components of the electronic control of the device and electrical components are provided.

In 2 is in a crude schematic way, a snapshot during the irradiation of a last on the build platform 13 prepared powder layer 21 shown. Starting from a first layer of powder on a substrate plate 25 has been prepared, has the building process of the molding 23 started and then layer by layer up to the in 2 indicated snapshot has been continued. The powder used is z. As metal powder or optionally ceramic powder or possibly a mixed powder. After the preparation of a respective powder layer on the build platform 13 this is done by means of a laser beam 27 Site-selective irradiated at the points where the powder is to be remelted to contiguous solidified areas. The laser beam 27 scans the current layer to be irradiated 21 in a controlled manner from, for this purpose z. B. an XY Galvanoscanner 29 is used. Furthermore, the control device controls the switch-on / switch-off phases of the laser beam 27 , In 2 is the laser beam 27 so focused that its focus on the surface of the powder layer 21 lies. The beam impact point 37 is thus extremely small at this point and the energy density of the laser beam in Strahlauftreffpunkt is very high. By adjusting the build platform or the focusing optics, these parameters can be varied.

In 3 is the process space of the 1 recognizable SLM device shown, wherein the housing 3 is shown in the largely disassembled state to release the view into the process room interior.

In the process room floor 11 is an opening of a building cylinder 33 recognizable in which the construction platform 13 vertically displaceable guided as a piston and controlled in the building cylinder 33 can be lowered to accommodate a respective new, currently to be irradiated layer on the process room floor surface.

A powder layer preparation device 41 includes a smoothing slide accommodated in the process space 43 , which is formed as a pivot arm, which is about a vertical pivot axis 45 between the in 3 shown first reversing position at a first reversal point and at a second reversing position, not shown, at a respective second reversal point back and forth. In such a pivoting movement of the smoothing slider passes 43 the build platform 13 in the process room floor 11 to get a smooth layer of powder on the build platform 13 to create. The smoothing slider 43 has a powder smoothing bar for this purpose 47 made of silicone or the like., The underside of the building platform 13 at the base level 51 of the process room floor 11 lies. The powder is introduced into the process space by means of a powder supply device 9 promoted. The supplied powder is passed through a powder inlet port 55 in the process room floor 11 from below into the process room 9 brought in. The Powder inlet 55 is located at a location between the build platform 13 and the in 3 reversal point of the smoothing bar 47 Also includes a powder replenishment waiting position of the smoothing slider 43 is.

After feeding a dosed amount of powder into the process room 9 through the powder inlet opening 55 The control of the SLM device causes the smoothing slide 43 to, from the in 3 to be pivoted to the second reversing position shown, so that the thereby advanced from the Pulverglättungsleiste powder to the building platform 13 arrives. The construction platform 13 is previously the measure of the desired powder layer thickness in its cylinder guide 33 been lowered. Because the smoothing bar 47 when sweeping the building platform with its underside at the base level 51 of the process room floor 11 Thus, a smoothed powder layer of the desired thickness is produced and then the irradiation process for the site-selective solidification of the previously prepared powder layer can begin.

The processes of the powder layer preparation on the building platform 13 and the site-selective solidification by irradiation of the powder repeat each other until the desired shaped body 23 ( 2 ) is completed. The leadership of the laser beam 27 during its scanning movement over the build platform 13 takes place in a known manner in accordance with Geometriebeschreibungsdaten of the molding in each case concerning the currently irradiated layer.

In 3 is another hole 61 in the process room floor 11 recognizable. This serves z. For example, excess powder from the process room floor 11 dissipate after completion of the molding. This can be done manually using the sealing gloves (not shown) at the access openings 19 done with a sweeping tool or the like. In a variant not shown are suction, z. For example, a suction cup to be inverted over the building cylinder is provided in order to remove powder from the process space via a suction line extending from the suction bell.

According to the invention, the sides of the process space walls facing the process chamber interior are 11 . 72 . 74 with a non-stick coating 75 fully equipped. This concerns the soil 11 , the back wall 74 , the side wall 72 as well as an in 3 not shown, the side wall 72 opposite further side wall and a in 3 not shown, the back wall 74 opposite front wall, in which a viewing window 15 ( 1 ) is provided. This also relates to a not visible in the figures ceiling of the process room space 9 , in the window or a lens for illumination and the passage of the laser beam 27 are provided. Furthermore, the smoothing slider is also available 43 on its outer surface with an anti-adhesive layer, preferably with the exception of Pulverglättungsleiste 47 , As a material of the non-stick layer is preferably ceramic in question, which offers a bright, preferably white surface of the process space walls in daylight. Windows and optical imaging components are preferably not or provided with a transparent release material.

Preferably, also supply lines to the powder inlet opening 55 and discharges from the powder outlet 61 lined with a non-stick coating inside.

In the sidewall 72 are openings 73 recognizable, can flow through the protective gas. In the not shown, the sidewall 72 opposite side wall openings are provided for the removal of the protective gas, preferably in a closed protective gas cycle. Not shown is a device for blowing gas into the process space and for sucking gas and possibly transported material powder from the process space. This can be a blow drum and a proboscis or, if necessary, a combined blower / proboscis. After completion of a shaped body and the coarse removal of the residual powder, remaining residual powder can then be whirled up with the blowpipe, so that it can then be sucked out of the process space with the aid of the suction pipe. Due to the poor adhesion of the non-stick layers to the process space wall surfaces, it is relatively easy to remove scattered residual powder in this way. The white inner lining of the process space also allows easy detection of metal powder residues, which helps to clean the process space 9 also relieved.

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

• WO 2010086327 A1 [0002, 0004]
• DE 19905067 A1 [0002]
• DE 10112591 A1 [0002]
• WO 98/24574 A [0002]
• WO 2006024373 A2 [0002]
• EP 2286982 A1 [0004]
• EP 1793979 B1 [0006, 0023]
• EP 2522446 A1 [0006]
• DE 202010018017 U1 [0006, 0011, 0011, 0011]
• EP 2286982 B1 [0012]

Claims (14)

Device for producing a shaped body by locally remelting or optionally sintering of material powder to contiguous areas of the shaped body in accordance with Geometriebeschreibungsdaten of the shaped body by energy input by means of radiation ( 27 ), in particular laser radiation, in a process space ( 9 ), which has a floor ( 11 ), a ceiling and side walls ( 72 . 74 ), characterized in that the bottom ( 11 ) and / or the ceiling and / or at least one of the side walls ( 72 . 74 ) on the process chamber side with a non-stick coating ( 75 ) is made of a non-stick material or are or are formed from such a non-stick material. Device for producing a shaped article according to claim 1, characterized in that the bottom ( 11 ), the ceiling and the side walls ( 72 . 74 ) possibly with the exception of windows and openings on the process chamber side substantially completely over the entire area with the non-stick coating ( 75 ) are provided. Apparatus for producing a shaped article according to one of the preceding claims, characterized by a device for injecting gas into the process space and for sucking off gas and optionally transported material powder from the process space. Apparatus for producing a shaped article according to one of the preceding claims, characterized in that at least one powder feed channel for supplying material powder to the process chamber opens into this and that this powder feed channel is also provided with a non-stick coating. Device for producing a shaped article according to one of the preceding claims, characterized in that at least one powder discharge channel for discharging material powder from the process space opens into this and that this powder discharge channel is also provided with a non-stick coating of a non-stick material. Device for producing a shaped article according to one of the preceding claims, characterized in that the bottom has an opening to a building cylinder ( 33 ) having a displaceable piston guided therein, which is a building platform ( 13 ) forms for shaped bodies, wherein the piston and the building cylinder are at least partially provided with a non-stick coating of a non-stick material. Apparatus for producing a shaped article according to one of the preceding claims, characterized by a powder layer preparation device for preparing material powder layers to be successively provided on a construction platform for site-selective irradiation, wherein the powder layer preparation device has components in the process space which are at least partially provided with a non-stick coating of a non-stick material and to which a smoothing slider ( 43 ) to level the powder layers on the build platform. Apparatus for producing a shaped article according to one of the preceding claims, characterized by at least one lock chamber between the process chamber and the external environment of the device, wherein the lock chamber is also lined with a non-stick coating of a non-stick material. Device for producing a shaped article according to one of the preceding claims, characterized in that the non-stick material comprises a ceramic material and / or a PTFE or / and a nanostructured material. Apparatus for producing a shaped article according to one of the preceding claims, characterized in that the non-stick material on the surface is bright, preferably white in daylight illumination. Pulversiebvorrichtung for sifting material powder, in particular for a device for producing a shaped article according to one of the preceding claims, comprising a screen containing a powder sieve, characterized in that the walls of the screen chamber and / or the powder sieve having a non-stick coating of a non-stick material or is formed from such a non-stick material or are. A powder screening apparatus according to claim 11, characterized by at least one pipe for material powder transport connected to the screen chamber, said pipe being provided with a non-stick coating of a non-stick material. Powder screening device according to claim 11 or 12, characterized in that the non-stick material comprises a ceramic material and / or a PTFE and / or a nanostructured material. Powder screening device according to claim 11, 12 or 13, characterized in that the non-stick material on the surface is white.

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