DE102019215388A1 - Device with variable focus for the production of objects by building them up in layers from powdery material - Google Patents

Abstract

The invention relates to a device for producing objects by building them up in layers from powder material. It comprises a structural volume housing (16) with a peripheral wall (18), a base plate arrangement (12) within the structural volume housing, the peripheral wall (18) and the base plate arrangement (12) being movable relative to one another, a powder layer preparation device for forming a respective material powder layer (20) for updating a construction field (7), an irradiation device (30) for the location-selective irradiation of the last prepared material powder layer (20) for the purpose of the locally targeted remelting of the powder and an upper process chamber housing (4) that accommodates the powder layer preparation device to form a sealed cavity as a process chamber the construction site. A focal length and / or a focus and / or a focus diameter of the irradiation device (30) can be adjusted in two different ways, so that a minimally achievable focus can be changed, with the smallest focus compared to a large one with a short distance between the irradiation device and the construction field Distance results. This makes a multifunctional AM machine possible.

Description

• - ein Bauvolumengehäuse mit einer seitlichen Umfangswandung,
• - eine Basisplattenanordnung zur Stützung eines Baufeldes, wobei die Umfangswandung und die Basisplattenanordnung relativ zueinander mittels einer Antriebsanordnung bewegbar sind, um das innere Volumen des Bauvolumengehäuses oberhalb der Basisplattenanordnung zu variieren,
• - eine Funktionseinrichtung mit einer Pulverschichtenpräparationseinrichtung zur Bildung einer jeweiligen Werkstoffpulverschicht zur Aktualisierung des Baufeldes,
• - eine Bestrahlungseinrichtung zur ortsselektiven Bestrahlung der jeweils zuletzt zur Aktualisierung des Baufeldes präparierten Werkstoffpulverschicht in einem dieser Schicht zugeordneten Querschnittsbereich des betreffenden herzustellenden Gegenstandes oder ggf. der betreffenden Gegenstände mit Strahlung, insbesondere mit Laserstrahlung, wobei die Strahlung das Werkstoffpulver in diesem Querschnittsbereich durch Erhitzen zum Verschmelzen oder ggf. zum Versintern bringt, und
• - ein oberes Prozessraumgehäuse zur Bereitstellung eines während eines Bauprozesses gegenüber der Außenumgebung abgedichteten Hohlraumes über dem Baufeld.

The invention relates to a device for the production of objects by building them up in layers from powdery, in particular metallic and / or ceramic material in a building process, comprising:

• - a volume housing with a lateral peripheral wall,
• a base plate arrangement for supporting a construction field, wherein the peripheral wall and the base plate arrangement can be moved relative to one another by means of a drive arrangement in order to vary the inner volume of the construction volume housing above the base plate arrangement,
• - a functional device with a powder layer preparation device for the formation of a respective material powder layer for updating the construction area,
• - an irradiation device for the location-selective irradiation of the material powder layer last prepared to update the construction area in a cross-sectional area of the relevant object to be manufactured or, if applicable, the relevant objects with radiation, in particular with laser radiation, the cross-sectional area assigned to this layer, wherein the radiation fuses the material powder in this cross-sectional area by heating or possibly sintering, and
• - An upper process space housing for providing a cavity above the construction field that is sealed off from the outside environment during a construction process.

Such a construction process is also known as additive manufacturing (AM).

The invention relates in particular to a device for the production of shaped bodies according to the principle of selective laser melting or selective laser sintering. For the state of the art relating to the field of selective laser melting, reference can be made, for example, to DE 199 05 067 A1 , DE 101 12 591 A1 , WO 98/24574 A , DE 10 2009 038 165 A1 , DE 10 2012 221 641 A1 , EP 20 52 845 A2 , DE 10 2005 014 483 A1 or WO 2017/084781 A1 to get expelled.

It is known that with the method of selective laser melting moldings such as machine parts, tools, prostheses, pieces of jewelry etc. can be produced in accordance with geometry description data of the corresponding moldings by building up layers of metallic or ceramic material powder, with several layers of powder being applied one on top of the other in one production process and each powder layer is heated with a normally focused laser beam in a predetermined area, which corresponds to a selected cross-sectional area of the model of the shaped body, before the application of the next powder layer, so that the material powder in the irradiated areas is remelted to form cohesive solidified sections. The laser beam is guided over the respective powder layer in accordance with the geometry description data of the selected cross-sectional area of the shaped body or possibly data derived therefrom. In selective laser melting, the material powder is normally applied as a binder- and flux-free, metallic, ceramic or mixed metallic / ceramic material powder and heated to its melting temperature by the laser beam, the energy of the laser beam being selected so that the material powder is at the point of impact The laser beam is melted as completely as possible over its entire layer thickness. A protective gas atmosphere, e.g. argon atmosphere, is usually maintained above the zone of interaction between the laser beam and the material powder.

Irradiation devices with a different focus diameter are used depending on the object to be produced.

Here, the focus diameter is to be understood as the diameter of the beam generated by the irradiation device in the focus or the focal plane and / or in the focal plane.

When calculating optical systems, ideal lenses and ideally generated radiation are often assumed. A bundle of rays hitting a lens in parallel, i.e. a number of rays hitting the lens parallel to the optical axis, is - at least with certain types of lenses - focused in a point after passing through the lens, the focus or focal point. This takes place in the focal plane or focal plane of the lens, which is at a distance from the lens that is dependent on the properties of the lens.

However, these theoretical calculations show the inaccuracy that in practice there are neither ideal lenses nor ideally generated radiation. Thus, a real radiation source will neither generate pure radiation or rays parallel to the optical axis, nor will a real lens deflect all rays arriving parallel to the optical axis exactly onto the focus.

Even with the greatest precision, the rays actually become real in a mostly circular or focused elliptical focus area, which is close to the calculated focal plane and in the middle area of which the calculated focus is located.

The size of this area is called the "focus diameter". In the case of a circular shape, this is usually the actual diameter of the circle. In the case of an ellipse, this is usually the length of the main axis of the ellipse. In general, the “focus diameter” usually denotes the largest diameter of the focus area. However, in a specific case, the “focus diameter” can also be, for example, the area of the focus area or another variable that provides information about the extent and / or shape, such as the mean value or root mean square value of the main axis and minor axis for ellipses and / or several values such as Example length of main axis and ratio of main axis to minor axis. It is only important that the focus diameter is a measure of how strong the deviation from a theoretically punctiform focus is.

A small focus diameter is advantageous for a particularly precise production of an object with many fine structures. Furthermore, with a smaller focus diameter, a lower radiation power is sufficient to melt the powder.

A large focus diameter, on the other hand, can scan larger areas faster.

Since the actual scanning of the construction field is often carried out with a scanner mirror and the angle of rotation of the scanner mirror is limited, a large distance from the construction field is also advantageous, since the accessible area of the construction field is then larger. Thus, advantages can be achieved by accepting a large focus diameter.

Accordingly, there are generic devices with a small focus diameter and those with a large focus diameter, since, depending on the application, one offers advantages over the other.

The present invention is based on the object of designing a device of the type mentioned at the beginning or an associated method in such a way that the requirements with regard to focus diameter of various applications are met.

This object is achieved by a device according to claim 1 and / or a method according to claim 14. Advantageous embodiments are the subject matter of the dependent claims.

The minimum focus of an optical device essentially depends on the distance, which is to be set according to the focal length, of the focusing device to the target field, provided that an ideal beam source with optimal beam properties is available (e.g. a laser beam with a diffraction index M ² = 1) and ideal wavelength. The shorter the distance, the smaller the focus that can be achieved. With a suitable choice of the optical components, it is possible to focus the system for different large distances. The greater the distance, the greater the minimum adjustable focus. This property is intended to be used in the AM machine proposed according to the invention.

For this purpose, it is proposed according to the invention that, in such a device, a focal length, a focus and / or a focus diameter of the irradiation device can be adjusted in two different ways, preferably one type with a small but faster adjustment and the other type with a slower but larger adjustment, in particular one type preferably designed for small and fast adjustment during the site-selective irradiation and the other type for slower and larger adjustment, in particular before a manufacturing process and / or during the manufacturing process and / or during an update of the construction field.

This makes it possible to adjust the focus and / or focus diameter, which is ideal for the current manufacturing process, by means of one type in each case to a minimum value, while by means of the second type a quick fine adjustment is preferably carried out in order to accommodate the geometrically different path lengths from the irradiation device to different areas of the construction area such as the center and corners and, in addition, to not work in the smallest focus for certain scan geometries. As a result, applications with different requirements in terms of focal length, i.e. minimal focus, can be carried out one after the other or even within a process in the same machine, but also on a component if the component has very filigree areas and coarser areas.

In preferred embodiments, in each changed focal length position, the minimum adjustable focus is kept constant in a certain path length range by a very rapidly dynamically movable lens according to the second type, in order to keep the focus constant in one plane, for example for a scanning system. By changing the position of this “fast lens”, however, it can also be defocused in this plane.

This can be used to reduce the energy input or the heating in some areas through slight defocusing and / or to make transitions between different ones Solidification areas, in particular areas with and without solidification to make sharper or less sharp.

For example, it can be advantageous to first move around the border of an area to be consolidated with a somewhat higher energy input. As a result, the boundary is more sharply defined and since the powder is still not solidified inside and outside the wall, the greater heat can also be better dissipated. When solidifying the inner edge of the border, a slight defocusing is often advantageous, for example because the lower heat dissipation capacity due to the existing border is compensated for and / or because larger areas can be covered and the inner surface can be solidified more quickly.

To adjust the minimum possible focus diameter, it is sufficient to adjust the focal length of the optical system.

The term “construction area” is preferably to be understood as the upper surface of the last prepared material powder layer, because this is where the heat input defined by the focus takes place to melt the metal or plastic powder used, i.e. the “building” or assembly of the object to be manufactured.

For example, the length of the beam path towards the construction field can be adjusted to a small extent by moving the base plate arrangement. Alternatively, the entire construction volume housing could also be moved.

A length of a beam path and / or a distance from a last optical element of the irradiation device and / or a radiation source of the irradiation device to the construction field, the base plate arrangement, the process space housing and / or the volume housing is preferably adjustable, in particular without adjusting the base plate arrangement, process space housing and / or build volume housing.

Such an adjustment is preferably carried out by a movable mounting and a movement by means of a drive. As a result, the distance can also be adjusted at short notice and during a manufacturing process.

However, in some embodiments it can also be provided that corresponding elements are releasably fastened at different heights above the construction field. For a new manufacturing process, the construction field and the process room housing and other components have to be serviced or set up for the next process. A corresponding detachable connection can also be released, the desired distance can be set and then a new connection can be established. This allows a simpler construction and the elimination of corresponding drive and storage means.

In particular, the length of a beam path from or a distance between an element influencing the focus and / or focal length, such as a lens, a lens system and / or an optics module, and the construction field is preferably adjustable.

Because in some embodiments the last optical element has no effect on the focal length, so that the distance between the last optical element and the construction field is not necessarily decisive, but the distance or length of the beam path from the last element influencing the focal length. In some embodiments, the distance and / or length of the beam path between the last element influencing the focal length and the construction field is consequently preferably adjustable.

An “optical element” is to be understood here as an element that does not simply allow the radiation to pass, but influences it in some other way, for example refracts, reflects, focuses, diffuses or the like. The “last optical element” thus identifies the last element of the irradiation device, which influences how and in which direction the radiation leaves the irradiation device in the direction of the construction field.

Preferably, there are no further optical elements between the last optical element of the irradiation device and the construction field, but at most windows and / or panes and the like that do not influence the radiation, or only slightly or at least in a non-adjustable manner. For example, a window and / or pane could also be provided, as a result of which the radiation is refracted in a known and possibly location-dependent manner. However, windows and / or panes, for example, which allow the radiation to pass through virtually unhindered and unaffected, are preferred.

By adjusting the beam path appropriately, in combination with adjusting the focal length or focus, the focus diameter can be flexibly set to the desired value. In this case, limits for maximum and minimum focus diameter may be given by the properties of the irradiation device and / or the possible adjustment range of the beam path.

The last optical element is preferably or comprises at least one mirror, in particular a deflecting mirror and / or a scanner mirror, which is preferably mounted so that it can be rotated and / or tilted and can be moved in a controlled manner that the radiation can be directed onto a large area, preferably onto any point of the construction site. The last optical element can, however, also comprise a plurality of movable mirrors which, through interaction, allow the radiation to be aligned over a large area of the construction field. For example, the last optical element can comprise two scanner mirrors, by means of which the deflection of the radiation can be adjusted in one spatial direction, the two spatial directions being orthogonal to one another.

Such mirrors allow the beam and thus the focus and thus the location of the greatest heat input to be guided relatively quickly over the entire construction field, so that complex structures can be built up relatively quickly.

An alternative is to move the last optical element essentially in the plane parallel to the construction field. It is also possible to move the entire irradiation device parallel to the construction field.

As a result, a large area or even every location of the construction site can be reached with radiation, but this is generally slower than the version with tiltable and rotatable scanner mirrors.

The last optical element can preferably be displaced perpendicular to the construction field, in particular by means of a linear drive.

This represents a technically simple solution for adjusting the beam path and / or the distance to the construction field.

Alternatively or additionally, however, other elements of the irradiation device can also be designed to be displaceable with respect to the construction field and / or the optical axis. For example, the radiation source or deflection mirror can be used for this. The length of the beam path can also be influenced by shifting such elements along the optical axis and / or perpendicular to the construction field.

“Optical axis” is here to be understood in the usual sense of optics as the axis of symmetry of a rotationally symmetrical optical system. This applies in particular to embodiments in which there is a straight beam path from the radiation source to the last optical element. In these cases, the optical axis is the axis of symmetry of the optical system starting from the exit of the radiation source (the radiation source is not necessarily designed to be rotationally symmetrical).

However, there are also design variants in which the radiation path goes from the radiation source to a deflecting mirror and from there to further deflecting mirrors and / or to the last optical element.

In this case, in the usual optics sense, there are preferably several optical axes angled to one another, because a respective section between the radiation source, deflection mirrors and / or the last optical element is preferably locally rotationally symmetrical. For example, in that only rotationally symmetrical elements are arranged within a section.

In simplified terms, however, within the scope of the invention, the term “optical axis” is to be understood as the entirety of the optical axes joined to one another at an angle in the sense of optics, which together form the beam path within the irradiation device.

Furthermore, within the scope of the invention, the term “optical axis” also includes the line in which a beam traveling on this line would hit the center of the focus area and / or the focal area. This conceptual meaning is particularly relevant for systems that do not generate a circular focus area, but an elliptical one, for example. Correspondingly, in embodiments with non-rotationally symmetrical optical systems, “optical axis” is to be understood as the line in which a beam traveling on this line would hit the center of the focal area and / or the focal area.

In some embodiments, in particular those without a scanner mirror, the last optical element is preferably also displaceable in all directions parallel to the construction field, preferably by two linear drives coupled to one another, aligned orthogonally to one another and aligned parallel to the construction field.

This allows a particularly precise grid of the construction area.

The process chamber housing is preferably closed and / or sealed on the top by a pane and / or window permeable to the radiation of the irradiation device, the irradiation device preferably being arranged at least partially above the process chamber housing, preferably completely above the process chamber housing. The last optical element of the irradiation device is preferably arranged above the process chamber housing.

As a result, elements of the irradiation device or the entire irradiation device can be moved and / or adjusted This is easier because, on the one hand, a collision with elements moving inside the process chamber housing is ruled out and, on the other hand, it is avoided that the irradiation device has to be moved within the sealed cavity, which could require a more complicated connection to the drive means / motors.

The irradiation device preferably comprises an optics module with at least one focus lens and / or at least one lens system, the optics module as a whole and / or the at least one focus lens or the lens system being movable along an optical axis in order to adjust the focal length and / or that of the irradiation device, wherein the at least one focus lens or the lens system is preferably designed as a plurality of focus lenses that are fixed relative to one another.

Moving the optics module along the optical axis changes the length of the beam path from the radiation source to the optics module and from the optics module to the construction field. This influences how far behind the last optical element the focus or the focal length of the irradiation device is and how large or small the possible focus diameter is. If the distance / beam path between the last optical element and the construction field is also adjusted appropriately, the focus diameter can be set to a desired value and lies exactly in or on the construction field.

In addition to the focus lens, the optics module preferably also comprises a fine focus lens movable along an optical axis and relative to the at least one focus lens for quick fine adjustment of the focal length and / or the focus and / or the focus diameter of the irradiation device, depending on the geometrically slightly different beam path lengths to compensate for the position on the construction field and possibly to scan certain geometries to be scanned with a slightly larger focus than the minimum adjustable.

As a result, the two different ways of adjusting the focal length, focus and / or focus diameter can be implemented in a technically simple manner.

In principle, both convex and concave lenses, as well as lenses of other types, and combinations of several different lenses for all lenses of a device according to the invention are possible. In particular, the focusing lens does not have to be a convex lens either. It can, for example, also be a combination of several lenses or also a convex lens which, in combination with further lenses and / or the lens system, leads to a focusing of the radiation.

In one possible embodiment, the optical module is preferably coupled to the last optical element for joint movement and / or separately controllable so movably that the relative position of the optical module to the last optical element remains the same or can be kept the same if the length the beam path and / or the distance between on the one hand the last optical element and / or the radiation source and on the other hand the construction field is adjusted, the beam path preferably running from a beam exit of the optical module to the last optical element parallel to the construction field, preferably along a straight line.

This mechanically ensures that any adjustment of the distance between the last optical element and the construction field represents a change in the length of the beam path, which ensures that the length of the beam path towards the construction field is complementary to a change in the focal length and / or the focus it can be changed that the focal length or focus lie exactly in the construction field.

The optics module and the last optical element are preferably arranged in or on a radiation housing, the radiation housing being movable perpendicular to the construction field in order to adjust the length of the beam path between the last optical element and the construction field. This can preferably be done by a linear drive.

In this way, the adjustment of the distance and / or the length of the beam path is technically easy to implement.

In another possible embodiment, the optical module is not coupled to the last optical element for joint movement, so that the relative position of the optical module to the last optical element changes when the length of the beam path between the last optical element and the construction field is adjusted.

This can be advantageous since the optics module mostly comprises movable lenses and / or a lens system. Their precise positioning and thus the accuracy of the beam guidance and focusing is more likely to be guaranteed if the optics module is moved less often and / or less far. Why decoupling from the last optical element can be useful if it is moved often and / or far.

In this embodiment, the last optical element and a deflecting mirror are preferred or arranged on a radiation housing, the beam path running from a beam exit of the optics module to the last optical element via the deflecting mirror and preferably further deflecting mirrors, in particular movable relative to the optics module.

The beam path can then be adjusted from the last optical element of the irradiation device to the construction field and / or from the beam exit of the optical module to the construction field without moving the optical module. In order to adjust the focus accordingly, the optics module then only has to be moved a little, with the result that the optics module is moved less overall.

This variant is therefore usually more optimal with regard to the service life or the precision of the optical module and / or other complex optical elements.

The device preferably comprises a data processing unit, a processor and / or a control unit which are designed and / or set up to adjust the beam path and / or the distance in particular between the last optical and / or the focus diameter when adjusting the focal length and / or the focus and / or the focus diameter. or to adjust the focal length influencing element and construction area accordingly so that a focal point and / or a focal plane lies on, in and / or on the construction field; and or
when adjusting the beam path and / or the distance, in particular between the last optical element and / or the element influencing the focal length and the construction surface, the focal length and / or the focus and / or the focus diameter are to be understood as corresponding, so that a focal point and / or a focal plane is in and / or on the construction site; and or
based on entered, fed in and / or transmitted information regarding the object to be manufactured focal length and / or focus and / or focus diameter and correspondingly to select and set the beam path and / or the distance in particular between the last optical element and the construction area.

This simplifies the operation of such a device and ensures that the focal plane and / or focus diameter are close to or in the construction field even when adjusted.

In devices according to the invention, the focus and / or the focus diameter are preferably adjustable between 1 μm and 1000 μm, preferably between 15 μm and 250 μm. The length of the beam path from a last optical element and / or the focal length influencing element of the irradiation device to the construction field and / or the distance between the last element and construction field can be adjusted between 10 mm and 3000 mm, in particular between 200 mm and 1000 mm.

The device according to the invention and / or the optics module is preferably designed in such a way that the fine focusing lens can be moved up to 10 mm along the incoming optical axis (axis in the direction of the x-mirror scanner). The device according to the invention and / or the optics module is preferably designed such that the optics module, the at least one focus lens and / or the lens system can be moved more than 5 mm along the optical axis, preferably 20 to 100 mm.

This means that most of the values required in practice can be set.

As an alternative or in addition, the displacement of the optical module and / or the at least one focus lens can also be replaced and / or supplemented by a displacement or displaceability of the radiation source in all embodiments. However, the movement of the optics module is technically usually simpler than the movement of the radiation source.

A glass fiber cable for guiding the radiation is preferably located in sections between the radiation source and the last optical element, particularly preferably between the radiation source and the optics module.

Particularly preferably, the fiber optic cable extends from the radiation source to a position that corresponds to the height of the last optical element and / or the optical module above the construction field, so that the radiation from the output of the fiber optic cable along the optical axis parallel to the construction area to the last optical Element and / or optics module runs.

Particularly preferably, the length and mounting of the fiber optic cable is designed and / or allows so much play that when adjusting the distance of the last optical element and / or the optical module to the construction field, the fiber optic cable can be moved up or down and the radiation can move the fiber optic cable further at the level of the last optical element and / or the optical module parallel to the construction field.

As a result, complex mirror constructions for the height-adjustable deflection of the radiation onto the optical module or the last optical element can be avoided.

• Verstellen der Brennweite und/oder des Fokus und/oder des Fokusdurchmessers der Bestrahlungseinrichtung; und dazu korrespondierende Verstellung des Strahlweges von dem letzten optischen und/oder die Brennweite beeinflussenden Element der Bestrahlungseinrichtung zu dem Baufeld und/oder des Abstandes des letzten optischen und/oder die Brennweite beeinflussenden Elements zu dem Baufeld, so dass ein Brennpunkt und/oder eine Brennebene auf, in und/oder am Baufeld liegt; und/oder die folgenden Schritte:
  • Verstellen des Strahlweges von dem letzten optischen und/oder die Brennweite beeinflussenden Element der Bestrahlungseinrichtung zu dem Baufeld und/oder des Abstandes des letzten optischen und/oder die Brennweite beeinflussenden Elements zu dem Baufeld; und dazu korrespondierende Verstellung der Brennweite und/oder des Fokus und/oder des Fokusdurchmessers der Bestrahlungseinrichtung, so dass ein Brennpunkt und/oder eine Brennebene auf, in und/oder am Baufeld liegt.

A method according to the invention for operating a device according to the invention with adjustable beam path or distance comprises at least the following steps:

• Adjusting the focal length and / or the focus and / or the focus diameter of the irradiation device; and corresponding adjustment of the beam path from the last optical and / or the focal length influencing element of the irradiation device to the construction field and / or the distance of the last optical and / or the focal length influencing element to the construction field, so that a focal point and / or a focal plane is on, in and / or on the construction site; and / or the following steps:
  • Adjustment of the beam path from the last optical and / or the focal length influencing element of the irradiation device to the construction field and / or the distance of the last optical and / or the focal length influencing element to the construction field; and corresponding adjustment of the focal length and / or the focus and / or the focus diameter of the irradiation device, so that a focal point and / or a focal plane lies on, in and / or on the construction field.

This ensures that the focal plane and / or focus diameter are close to or in the construction field even when adjusted.

• 1 zeigt in einer schematischen Schnittdarstellung einen prinzipiellen Aufbau einer erfindungsgemäßen Vorrichtung zur Herstellung von Gegenständen in einem Zustand mit großem Abstand zwischen letztem optischen Element und der Baufläche und mit großem Fokusdurchmesser.
• 2 zeigt in einer ebenso schematischen Schnittdarstellung die Vorrichtung aus 1 mit einem anders eingestellten Strahlweg/Abstand und anders eingestelltem Fokusdurchmesser.
• 3 zeigt in einer schematischen Schnittdarstellung einen prinzipiellen Aufbau einer weiteren erfindungsgemäßen Vorrichtung zur Herstellung von Gegenständen in einem Zustand mit großem Abstand zwischen letztem optischen Element und der Baufläche und mit großem Fokusdurchmesser.
• 4 zeigt in einer schematischen Schnittdarstellung einen prinzipiellen Aufbau einer weiteren erfindungsgemäßen Vorrichtung ähnlich zu 1 unter Verwendung eines Glasfaserkabels.

Embodiments of the invention are described below with reference to the attached 1 - 3 explained.

• 1 shows in a schematic sectional view a basic structure of a device according to the invention for the production of objects in a state with a large distance between the last optical element and the construction area and with a large focus diameter.
• 2 shows the device from FIG 1 with a differently set beam path / distance and a differently set focus diameter.
• 3 shows in a schematic sectional view a basic structure of a further device according to the invention for the production of objects in a state with a large distance between the last optical element and the construction area and with a large focus diameter.
• 4th shows in a schematic sectional illustration a basic structure of a further device according to the invention similar to FIG 1 using a fiber optic cable.

With 30th is in the 1 and 2 denotes an irradiation device which supplies laser radiation for remelting the material powder used. The irradiation facility 30th is above a process room housing 4th arranged. The process room housing 4th limited with its for radiation of the irradiation device 2 permeable upper disc 9 one as a combustion chamber 6th designated cavity above the exposure plane 7th that is also called a construction field 7th referred to as. The process room housing 4th mostly comprises or is mostly also connected to further elements, for example with a functional device with a powder layer preparation device (not shown) and with a protective gas supply device, which together form a production module. The powder layer preparation device usually comprises a powder feed device, not shown, which takes a respective quantity of material powder from a powder supply to form a respective material powder layer 20th on the construction field 7th applies. The powder layer preparation device further comprises a smoothing slide, not shown, for leveling the material powder to form a uniform material powder layer 20th on the construction site 7th . The smoothing slide can, for example, be a lip that is straight and horizontal on the underside and extends over the construction field 7th is moved away in order to distribute the powder deposited on it evenly.

The protective gas supply device preferably comprises protective gas inlet means for introducing protective gas, e.g. B. argon, in the combustion chamber 6th and protective gas discharge means for discharging protective gas and possibly process smoke from the combustion chamber 6th , wherein the protective gas inlet means and the protective gas outlet means can preferably be combined to form a protective gas circulation device which has gas filter devices.

A structural volume housing is located on a housing part of the device 16 with its peripheral wall 18th intended. Inside the building volume housing 16 is a base plate assembly 12th intended to support the construction site.

The one above the base plate assembly 12th intended inner volume of the structural volume housing 16 is made by lifting the perimeter wall 18th relative to a base plate assembly 12th with a base plate (and possibly a substrate plate arranged on it) larger. In the present exemplary embodiment, this is done by lowering the base plate arrangement by means of the lifting drive 15th .

The baseplate assembly 12th is on a building board carrier (elevator) 28 arranged, which is vertically movable by means of a controllable lifting drive to the base plate assembly 12th relative to the peripheral wall 18th raise or lower.

Such an arrangement of base plate arrangement 12th , Lifting drive 15th , Elevator 28 and build volume housing 16 with peripheral wall 18th is also known as a building cylinder.

On the base plate assembly 12th could still rest a substrate plate on which the molded body would be built. The baseplate assembly 12th could then remain intact and be used for a greater number of building processes. If necessary, several substrate plates could also rest on the base plate, e.g. B. side by side. This can be advantageous if several shaped bodies are produced in one work process, with each shaped body being able to be assigned its own substrate plate segment.

In the base plate arrangement 12th or / and in the peripheral wall 18th a respective heater could be integrated to warm up the building volume.

At the beginning of a construction process according to 1 is by means of the powder layer preparation device 10 a material powder layer 20th on the base plate assembly 12th or on the one on the base plate assembly 12th placed on the substrate plate and leveled. There is a solidification of desired areas within the material powder layer 20th by fusing the powder with the laser beam.

The the construction field 7th representing powder layer 20th is now by means of the irradiation device 2 irradiated, whereby the laser beam is deflected computer-controlled so that it hits the prepared powder layer 20th deliberately causes the areas to melt which a cross-sectional area of the object to be manufactured that is assigned to the relevant layer 24 corresponds to.

After the irradiation step, the elevator is then lowered 28 by an amount of height to the base plate assembly 12th relative to the peripheral wall 18th raise or lower. In other embodiments, the peripheral wall can also alternatively or additionally 18th or the volume housing 16 be designed to be movable around the base plate assembly 12th relative to the peripheral wall 18th raise or lower. Then it is usually the process room housing 4th also designed to be movable.

The amount of height corresponds to the layer thickness of the next powder layer. This is followed by the preparation and finally irradiation of this next powder layer in the manner explained. These processes are repeated until the desired item is obtained 24 is completed.

2 shows a similar intermediate stage in the manufacture of the article 24 how 1 with the main difference that the focal length and distance to the construction field 7th the irradiation facility 30th have changed. This results in a smaller focus diameter 35 than in 1 given, with which - as indicated schematically - a more filigree object can be produced.

At the same time, however, there is a smaller overall construction area due to the smaller distance. Because as indicated there is at the irradiation facility 30th an exit disk or exit window 31 , which is permeable or transparent for the laser beam. This limits the maximum exit angle of the laser beam and thus the maximum angle of the laser beam to the normal of the construction area 7th . At the same time, another limit can also be caused by the maximum tilt and / or rotation angle of a last optical element 34 be conditional.

This angle, in combination with the distance, determines the irradiation device 30th to construction site 7th the maximum area of the construction site that can be processed or irradiated 7th .

The device according to the invention thus allows different minimum focus diameters 35 to achieve, which go hand in hand with different advantages and disadvantages, with which the device according to the invention allows the setting of the focus diameter that is just optimal for the current application. As the focus becomes smaller, in the exemplary embodiment shown, the size of the possible construction field also decreases due to the maximum angle around the last optical element 34 can deflect the beam in relation to the vertical direction, which must be taken into account when selecting the minimum focus diameter and other process parameters. In other embodiments, however, this is achieved by shifting the entire optical module 36 in a plane parallel to the construction field (also called the XY plane), which means that you can work with a small minimum focus even in larger areas.

This is due to the design of the irradiation facility 30th enables. This includes a radiation source 42 to generate a laser beam. This is on a deflecting mirror 44 directed, which the laser beam on an optical module movable along the optical axis 36 diverts.

In this optics module 36 is a lens system 36b arranged, for example, three focus lenses 36b may include, which together produce a desired beam characteristic.

The optics module also includes 36 those along the optical axis 32 movable fine focus lens 36a namely also movable relative to the lens system 36b .

The position of the optics module 36 and / or the lens system 36b along the optical axis determines the focal length or the focus of the irradiation device 30th , i.e. the length of the beam path from the exit of the irradiation device 30th up to the focus point. The limits of the optical module 36 are shown schematically by dashed lines to the left and right of the lenses 36a , 36b indicated. This can be done by real slices similar to the exit slice 31 its or only theoretical limits for determining the overall optical properties and / or defining the possible range of motion of the movable fine focus lens 36a and / or the optics module 36 and / or the lens system 36b .

As can be seen the position of the lens system 36b or the optics module 36 in 1 and 2 differently. This is in 1 and 2 set a different focal length, resulting in a different focus diameter 35 or focus 35 results.

Since the focal length is in 2 is less, the distance between the exit of the irradiation device must 30th or the last optical element 34 and the construction site 7th be another.

Optical modules are used for this 36 , last optical element 34 and deflection mirror 44 in a radiation housing 40 arranged. This is done by means of the linear drive 38 perpendicular to the construction site 7th Movable up and down on the column, which is the radiation source 42 includes. A disk, indicated here by dashed lines, is usually on the top of the radiation housing 40 arranged so that the laser beam can enter and onto the deflecting mirror 44 can meet. Alternatively, the corresponding area can also simply be open, for example.

Because the deflection mirror 44 by arrangement in the radiation housing 40 always at the height of the optics module 36 and the last optical element 34 is independent of the adjustment by means of the linear drive 38 the laser beam is always suitable for the optics module 36 and finally over the last optical element 34 steered towards the construction site. This allows the distance and thus the beam path from the optics module 36 or the last optical element 34 to the construction site 7th within the through the top of the process room 4th and the bottom of the radiation source 42 set the specified limits (or a little less if the linear motor 38 and an associated guide are not designed to use the entire area anyway).

This allows within the scope of the adjustment of the optics module 36 or the lens system 36b of 1 to 2 at the same time adjust the vertical position of the radiation housing so that the focal length to the construction field again 7th corresponds or the focus / focus diameter 35 in or on the construction site 7th lies.

As a result, the device according to the invention allows the use of different focal lengths, foci and / or focus diameters.

The movement of the fine focus lens 36a on the other hand, is fast enough to compensate for the differences in the lengths of the beam path during a construction process, which result depending on whether the radiation is directed towards the center or the edge of the construction area.

Thus, the fine focus lens is 36a or their drive / movement device and thus a type of adjustment of the focus and / or the focal length designed for adjustment during a manufacturing process. The optics module is on the other hand 36 or its drive / movement device and thus the other type of adjustment of the focus and / or the focal length designed for adjustment outside of operation and preferably matched to an adjustment of the height of the last optical element above the construction field.

In 3 a device is shown which is relatively similar to that in FIG 1 and 2 is shown. Therefore, the same parts are also identified with the same reference numerals and - provided there are no differences - will not be explained again.

The irradiation facility 30th is structured a little differently. Here is the optics module 36 recorded as a whole within the column, which is also the radiation source 42 includes. The optics module also has the movable fine focus lens 36a and the movable lens system 36b on or the optics module 36 is movable itself, so that the focal length can be adjusted in two ways.

Although it could also be accordingly 1 and 2 following on the optics module 36 directly the deflection mirror 44 follow the laser beam onto the last optical element 34 diverts. However, then is the optics module 36 still directly affected by vibration when the radiation enclosure 40 is adjusted.

Therefore, in this exemplary embodiment designed for the least possible movement of the optics module, the radiation source is located in the 42 and the optics module 26th comprehensive column at the lower end of another deflecting mirror 44 , which directs the laser beam into the column on which the Radiation housing 40 by means of the linear drive 38 is movably mounted. This will be done through the movement of the radiation housing 40 resulting vibrations less easily on the optics module 36 transfer.

Another deflection mirror 44 in this column directs the laser beam onto the deflecting mirror 44 aiming the laser beam on the last optical element 34 diverts.

This ensures that upward and downward movements of the radiation housing 40 the least possible impact on the optics module 36 to have.

Thus, the device can be omitted 3 also similar to in 2 Set a different focus and, in particular, a different focus diameter, but the optics module 36 is less exposed to movement.

4th shows an embodiment essentially corresponding to that in FIG 1 The main difference is that the radiation comes from the radiation source 42 to the radiation housing 40 in a fiber optic cable 44a to be led. This has sufficient play in terms of length so that different heights of the irradiation housing can be set 40 above the construction field 7th is possible. In contrast to the embodiment in 1 can use it on the mirror 44 be waived.

In the embodiments shown, the last is optical element 34 a scanner mirror 34 which can be tilted and rotated in such a way that a considerable part of the construction area can be reached with the laser beam, so that the material powder layer is formed in a combination of switching the laser beam on and off and moving the scanner mirror appropriately 20th can be melted and thus solidified in the desired cross-sectional areas.

Alternatively, a combination of several scanner mirrors can also be used 34 be provided, of which, for example, one controls the deflection of the laser beam along the construction area in the plane of section of the figures and the other controls the deflection orthogonal to the plane of section of the figures.

QUOTES INCLUDED IN THE DESCRIPTION

This list of the documents listed by the applicant was 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.

Patent literature cited

• DE 19905067 A1 [0003]
• DE 10112591 A1 [0003]
• WO 98/24574 A [0003]
• DE 102009038165 A1 [0003]
• DE 102012221641 A1 [0003]
• EP 2052845 A2 [0003]
• DE 102005014483 A1 [0003]
• WO 2017/084781 A1 [0003]

Claims (15)

Device for the production of objects (24) by building up in layers from powdery, in particular metallic and / or ceramic material in a building process, comprising: - a building volume housing (16) with a lateral peripheral wall (18), - a base plate arrangement (12) for supporting a Construction field (7), the peripheral wall (18) and the base plate arrangement (12) being movable relative to one another by means of a drive arrangement in order to vary the inner volume of the construction volume housing (16) above the base plate arrangement, - a functional device with a powder layer preparation device for forming a respective one Material powder layer (20) for updating the construction area (7), - an irradiation device (30) for the location-selective irradiation of the material powder layer (20) prepared last for updating the construction area (7) in a cross-sectional area of the relevant object (24) assigned to this layer or, if necessary, . the relevant objects with radiation, in particular with laser radiation, the radiation causing the material powder in this cross-sectional area to fuse or possibly sinter by heating, and - an upper process chamber housing (4), the functional device preferably being part of the upper process chamber housing (4) in the upper process chamber housing (4) is arranged and / or the upper process chamber housing (4) is arranged to provide a cavity (6) above the construction field (7) which is sealed off from the external environment during a construction process, characterized in that a focal length and / or a focus and / or a focus diameter (35) of the irradiation device (30) is adjustable in two different ways, preferably one type with small but fast adjustment and the other type with slower but large adjustment, in particular one type preferably designed for adjustment during the location-selective Radiation and the other way to adjust to a m manufacturing process and / or during the manufacturing process and / or during an update of the construction field. Device according to Claim 1 , characterized in that a length of a beam path and / or a distance from a last and / or the focal length influencing optical element of the irradiation device and / or a radiation source of the irradiation device to the construction field, the base plate arrangement, the process room housing (4) and / or the Building volume housing is adjustable, preferably without adjusting the base plate arrangement, process room housing and / or building volume housing, the length of a beam path and / or a distance from an optics module (36) to the construction field (7) being preferably adjustable. Device according to Claim 2 , characterized in that the last optical element comprises and / or is at least one mirror, in particular a deflecting mirror and / or a scanner mirror, which is preferably rotatably and / or tiltably mounted and controllably movable that the radiation on a large Area and can preferably be directed to any point on the construction site. Device according to Claim 2 or 3 , characterized in that the last optical element can be displaced perpendicular to the construction field, in particular by means of a linear drive (38), with the last optical element and / or the optical module preferably also being displaceable in all directions parallel to the construction field, preferably by means of two mutually coupled, Linear drives aligned orthogonally to each other and parallel to the construction site. Device according to one of the preceding claims, characterized in that the process chamber housing (4) is closed on the top by a pane (9) which is transparent to the radiation from the irradiation device (2) and that the irradiation device (2) is arranged at least partially above the process chamber housing (4) is, preferably completely above the process chamber housing, with reference to Claims 2 or 3 preferably the last optical element of the irradiation device is arranged above the process chamber housing. Device according to one of the preceding claims, characterized in that the irradiation device (30) comprises an optics module (36) with at least one focus lens (36b), wherein the optics module (36) as a whole and / or the at least one focus lens (36b) along a The optical axis is movable to adjust the focal length and / or the focus and / or the focus diameter (35) of the irradiation device (26), wherein the at least one focus lens (36b) is preferably designed as a plurality of focus lenses (36b) that are fixed relative to one another. Device according to Claim 6 , characterized in that the optical module (36), in addition to the at least one focus lens (36b), also has a fine focus lens (36a) movable along the optical axis (32) and relative to the at least one focus lens (36b) for adjusting the focal length and / or the Focus and / or the focus diameter (35) of the irradiation device (26). Device according to at least one of the Claims 6 or 7th in their reference to one of the Claims 2 to 4th , characterized in that the optical module is coupled to the last optical element for common movement and / or is separately movable and controllable in such a way that the relative position of the optical module to the last optical element remains the same and / or is the same when the Length of the beam path and / or the distance between on the one hand the last optical element and / or the focal length influencing element and / or the radiation source and on the other hand the construction field is adjusted, the beam path from a beam exit of the optical module to the last optical element parallel to the construction field being preferred along a straight line. Device according to Claim 8 , characterized in that the optical module and the last optical element are arranged in or on a radiation housing (40), the radiation housing being movable perpendicular to the construction field in order to understand the length of the beam path between the last optical element and the construction field. Device according to at least one of the Claims 6 or 7th in their reference to one of the Claims 2 to 4th , characterized in that the optical module is not coupled to the last optical element for joint movement, so that the relative position of the optical module to the last optical element changes when the length of the beam path between the last optical element and the construction field is adjusted. Device according to Claim 10 , characterized in that the last optical element and a deflecting mirror are arranged in or on a radiation housing, the beam path running from a beam exit of the optical module to the last optical element via the deflecting mirror and preferably further deflecting mirrors, in particular movable relative to the optical module, so that the The beam path from the last optical element of the irradiation device to the construction field and / or from the beam exit of the optical module to the construction field can be adjusted without moving the optical module. Device according to one of the preceding claims, characterized in that the device comprises a data processing unit, a processor and / or a control unit which is designed and / or set up to adjust the beam path and / or the focus and / or the focus diameter when the focal length and / or the focus and / or the focus diameter are adjusted / or to understand the distance in particular between the last optical element and / or the focal length influencing element and the construction area corresponding to this, so that a focus and / or a focal plane lies on, in and / or on the construction field; and / or when adjusting the beam path and / or the distance, in particular between the last optical element and / or the element influencing the focal length and the structural area, the focal length and / or the focus and / or the focus diameter can be adjusted accordingly, so that a focus and / or a Focal plane is on, in and / or on the construction field; and / or based on information entered, fed in and / or transmitted with regard to the object to be manufactured focal length and / or focus and / or focus diameter and, corresponding thereto, the beam path and / or the distance in particular between the last optical and / or the focal length influencing element and the construction area and adjust. Device according to one of the preceding claims, characterized in that the focus and / or the focus diameter is adjustable between 1 µm and 1000 µm, preferably between 15 µm and 150 µm, the length of the beam path from a last optical element to the irradiation device being particularly preferred the construction field and / or the distance between the last optical element and the construction field is adjustable between 10 mm and 3000 mm, in particular between 200 mm and 1000 mm. Device according to one of the preceding claims, characterized in that the device comprises a glass fiber cable for guiding the radiation in sections, preferably arranged with play between a radiation source and a last optical element of the irradiation device. Method for operating a device according to one of the preceding Claims 2 to 14th , wherein the method comprises at least the following steps: adjusting the focal length and / or the focus and / or the focus diameter of the irradiation device (2); and corresponding adjustment of the beam path from the last optical element of the irradiation device to the construction field and / or the distance of the last optical and / or the focal length influencing element to the construction field, so that a focus and / or a focal plane on, in and / or on Construction field is located; and / or the following steps: adjusting the beam path from the last optical and / or the focal length influencing element of the irradiation device to the construction field and / or the distance of the last optical and / or the focal length influencing element to the construction field; and corresponding adjustment of the focal length and / or the focus and / or the focus diameter of the Irradiation device, so that a focal point and / or a focal plane lies on, in and / or on the construction field.

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