DE102017126274B4 - Slip application unit and method for layer application for slip-based additive manufacturing - Google Patents

Abstract

An application device (10) for additive manufacturing, configured for at least one predetermined rectilinear movement direction (20) during application of a coating material (4), comprising a working volume for receiving the application material (4), wherein the working volume is at least laterally enclosed by a wall, and a bottom surface having a substantially rectangular opening (30) disposed in the bottom surface, the long sides of the substantially rectangular opening (30) extending in an orthogonal direction to the rectilinear moving direction (20) and edges defining the long sides being identical Have distances to a plane defined by the direction of movement (20).

Description

The invention is in the field of additive manufacturing and relates to an application device and layer application unit, in particular a double doctor blade, for the layered application of slurry on a job surface.

• - Aufbau einer Pulverschicht;
• - lokale Konsolidierung des Pulvers durch Einspritzen von Binder durch einen Druckkopf oder durch lokales Sintern mit einem fokussierten Laserstrahl;
• - Absenken der Bauplattform um die Schichtdicke.

Powder-based additive manufacturing is based on the stacking of individual powder layers and the local consolidation of the powder to the desired component. The layers can be applied by means of a flowable powder or a suspension with subsequent drying. The process can be described by the following three steps, which repeat repetitively:

• - Construction of a powder layer;
• local consolidation of the powder by injecting binder through a printhead or by local sintering with a focused laser beam;
• - Lowering the build platform by the layer thickness.

In the previously known LSD method (layer-wise sludge deposition), the buildup of a powder layer is carried out by applying a ceramic suspension (slip) and then drying this layer into a piece of broken glass. A technical problem is the layer order. This is done with a hollow blade that pushes a Schlickerberg in front of the hollow blade. The width of this Schlickerberg is not defined. Furthermore, due to the squeegee technology, the layer application can only take place by moving the squeegee from one side of the application surface. The squeegee must therefore drive once unused over the construction area to get back to the start after a completed shift order. In addition, precautions must be taken to prevent contamination of the previously applied layer by material falling from the squeegee during useless driving over.

In WO 00/78 485 A2 A device for supplying powder for a device for producing a three-dimensional object in layers is described. From DE 10 2014 010 951 A1 For example, there is taught a method and apparatus for dosing informal building material in a laminating process. DE 10 2015 003 372 A1 teaches a method and apparatus for producing 3D moldings from particulate building materials and particle loaded liquids with a double recoater. DE 10 2005 056 260 A1 teaches a method and apparatus for applying flowable material flatly. DE 10 2015 022 308 A1 teaches an apparatus and method for manufacturing a three-dimensional object with a heated powdered build material coater. Finally teaches WO 95/18715 A1 a method and apparatus for producing a three-dimensional object.

Against this background, a slip application unit according to claim 1 and a method for coating application according to claim 5 is proposed. Further embodiments, modifications, and improvements will become apparent from the following description of the appended claims and the attached drawings.

According to a first embodiment, a slip application unit comprising an application device for additive manufacturing is proposed, which is set up for at least one predetermined rectilinear movement direction during application of an application material. The application device comprises a working volume for receiving the application material, wherein the working volume is at least laterally enclosed by a wall, and has a bottom surface with an opening arranged in the bottom surface and substantially rectangular. Here, the long sides of the substantially rectangular opening extend in an orthogonal direction to the rectilinear moving direction, and the long sides of the substantially rectangular opening defining edges have identical distances to a plane defined by the moving direction. Furthermore, the slip application unit comprises an application surface, wherein the application device can be arranged above the application surface in such a way that a distance between the base surface and the application surface can be set to a constant value in a linear movement of the application device in a movement direction orthogonal to the long side of the substantially rectangular opening , The application surface comprises a surrounding edge surface and at least one parking station for the application device, wherein the parking station is arranged so that the substantially rectangular opening in the bottom surface of the application device during parking of the application device on the parking station is closed so that no application material from the Working volume can escape through the substantially rectangular opening, when a viscosity of the slurry is in a range of 0.1 Pa s - 5 Pa s.

Advantageously, when applying the application material with the described application device, the entire material emerging from the opening is introduced into the layer. The formation of a slip mountain before the application device is omitted. Thus, no loss of order material occurs. In addition, the applicator can apply a layer on the application surface when moving in two different directions. In order to the effectiveness of the layer structure over previously known types is significantly increased.

According to a development of the application device, a distance between long sides of the substantially rectangular opening is from 1 mm to 100 mm, preferably from 1 mm to 20 mm.

The layer formation takes place uniformly over the entire width of the application device. The working width of the applicator is defined by the length of the long sides of the substantially rectangular opening, which in the case of the application of a slurry is the slip exit opening or the slip exit slot.

According to a development, the substantially rectangular opening comprises the entire bottom surface of the working volume.

Advantageously, the slurry can pass unhindered over the entire width and length of the substantially rectangular opening. The exit speed of the application material (slurry) is determined so much for the given viscosity of the application material (slip) and given rate of progress alone by the level in the working volume.

According to a further embodiment, a height of the wall, measured from the bottom surface, is at least 50 mm.

Advantageously, this height allows many different fill levels of the application material, e.g. of a slip to provide in the working volume.

According to a further embodiment, a long side of the rectangular opening arranged in the bottom surface is at least 10-100 mm, typically at least 200-1100 mm.

An advantage of this embodiment results with an achievable maximum edge width of the component to be produced.

Advantage of this slip application unit is that when applying the application material with the slip application unit described, the entire material emerging from the opening of the applicator material is introduced into the layer. The formation of a slip mountain before the application device is omitted. Thus, no loss of application material occurs by pushing this Schlickerbergs of the order surface at the end of the shift order. In addition, the slip application unit can apply a layer on the application surface in each case in two opposite directions for each movement of the applicator. Thus, the effectiveness of the layer structure over previously known types is significantly increased.

According to a development of the aforementioned slip application unit, the constant value of the distance between the bottom surface of the application device and the application surface is from 20 μm to 1000 μm.

Advantageously, the sufficiently smooth outer contours of a produced green body.

According to a further embodiment, the slip application unit further comprises a linear motor for moving the application device over the application surface.

Advantageously, a linear motor can be adapted to different desired speeds of progression of the application unit over the application surface.

Advantageously, the edge surface described in claim 1 allows the formation of a clean edge of the applied layers and thus of the layer stack, since the edge surface, in contrast to the already applied to the application surface layers is not absorbent and thus no or very little material when passing over the opening is stored here. In addition, the distance between the edge surface can be adjusted independently of the working surface relative to the application device and minimized with the aim to deposit little material. In this context, distances smaller than 10 microns are advantageous.

According to a further embodiment, the edge surface is hydrophobic.

The wettability of the hydrophobic edge surface with the application material, ie the slip, is advantageously greatly reduced. Preferably, the typically aqueous slip does not wet the edge surface at all.

Advantageously, a loss of slip can be avoided by taking the parking position. During the consolidation step, the applicator remains operational, no slurry dries.

• - Bereitstellen einer Schlickerauftragseinheit gemäß zumindest einer der oben beschriebenen Ausführungsformen;
• - Anordnen der Auftragsvorrichtung (10) auf einer ersten Parkstation (9);
• - Befüllen eines Arbeitsvolumens der Auftragsvorrichtung (10) mit einem Schlicker (4), wobei eine Viskosität des Schlickers in einem Bereich von 0,1 Pa s - 5 Pa s liegt;
• - Bewegen der mit dem Schlicker (4) befüllten Auftragsvorrichtung (10) entlang einer Bewegungsrichtung (20) über die Auftragsfläche (6) mit einer konstanten Geschwindigkeit in einer Längsrichtung der Auftragsfläche (6) unter Einhalten eines konstanten Arbeitsabstands zwischen der im Wesentlichen rechteckigen Öffnung (30) der Auftragsvorrichtung (10) und der Auftragsfläche (6);
• - Anordnen der Auftragsvorrichtung (10) auf einer zweiten Parkstation (9), wobei die zweite Parkstation (9) an einer der ersten Parkstation (9) gegenüberliegenden Seite der Auftragsfläche (6) auf der die Auftragsfläche (6) umgebenden Randfläche (8) angeordnet ist, wobei die erste und die zweite Parkstation (9) eingerichtet sind, die rechteckige Öffnung (30) in der Bodenfläche der Auftragsvorrichtung (10) so zu verschließen, dass kein Schlicker (4) austreten kann.

Furthermore, a method for layer application for slip-based additive manufacturing is proposed. The method comprises:

• - Providing a slip application unit according to at least one of the embodiments described above;
• Arranging the applicator device ( 10 ) on a first parking station ( 9 );
• - Filling a working volume of the application device ( 10 ) with a slip ( 4 ), wherein a viscosity of the slurry is in a range of 0.1 Pa s - 5 Pa s;
• - moving the with the slip ( 4 ) filled applicator device ( 10 ) along a direction of movement ( 20 ) over the application area ( 6 ) at a constant speed in a longitudinal direction of the application surface ( 6 ) while maintaining a constant working distance between the substantially rectangular opening ( 30 ) of the application device ( 10 ) and the application area ( 6 );
• Arranging the applicator device ( 10 ) on a second parking station ( 9 ), the second parking station ( 9 ) at one of the first parking station ( 9 ) opposite side of the application surface ( 6 ) on which the application surface ( 6 ) surrounding edge surface ( 8th ), wherein the first and the second parking station ( 9 ), the rectangular opening ( 30 ) in the bottom surface of the applicator device ( 10 ) so that no slip ( 4 ) can escape.

In this case, the method is set up so that while moving with Schlicker ( 4 ) filled applicator device ( 10 ) a piece of broken glass ( 7 ) of a constant layer height on the application surface ( 6 ) is formed.

The above-described embodiments may be arbitrarily combined with each other.

In recent years, the demands on the manufacturing industry, especially in the field of development and prototype production have changed significantly. The increasing number of product variants, with greater complexity, is constantly increasing the need for prototypes. Under the heading "rapid prototyping" or "rapid manufacturing" a variety of new technologies have emerged, with the help of which the demand for more flexible production can be realized.

1. 1: Die Formgebung geschieht nicht durch Materialabtrag, sondern durch Zugabe von Material, oder durch den Phasenübergang eines Materials von flüssig nach fest bzw. es findet eine Kompaktierung eines pulverförmigen Ausgangsmaterials statt.
2. 2: Alle Verfahren bauen Teilgeometrien aus Schichten endlicher Dicke, die durch einen Slice-Prozess realisiert werden, direkt aus CAD-Daten auf.

The essential features of these methods are the creation of process control data from CAD geometry data with subsequent control of processing equipment. All of these methods share the following features:

1. 1: The shaping is done not by material removal, but by adding material, or by the phase transition of a material from liquid to solid or there is a compaction of a powdered starting material instead.
2. 2: All methods build part geometries from layers of finite thickness, realized by a slice process, directly from CAD data.

The currently available methods differ in the initial state of the materials (solid, liquid, pasty) in the layer addition or the construction process. There are a variety of methods that use a solid powdery material as the starting material, wherein when using free-flowing powder for the layer coating layers with only a low packing density of the powder particles are achieved, typically between 30 and 50% packing density.

There is a method which uses suspensions with a low content of organic additives for coating. This procedure is under US Pat. No. 6,827,988 B2 described. The LSD (Layer-wise Slurry Deposition) process applies ceramic green sheets via a process similar to film casting and, similar to selective laser sintering, uses a laser for local solidification / sintering of the ceramic green sheets. The green sheets have a packing density of the powder particles of over 60%. In combination with a print head, this coating order is also patent pending PCT / EP2012 / 060420 , international publication number WO 2012/164 078 A2 ,

The high packing densities of the powder particles in the powder bed cause the powder bed to form a free-standing block that encloses the component.

In the LSD process, suspensions of ceramic or metallic particles (hereafter called slip) are used to build up powder layers with a high packing density of the powder particles and to stack them with intervening local consolidation steps. On the typical square or rectangular working platform, a slip layer is applied and dried by means of a doctor blade. Subsequently, the powder particles are locally consolidated by laser sintering or injection of a binder.

In previous LSD technology, the slurry is applied via a hollow blade. The hollow blade comprises a gap in an elongate hollow doctor blade, the gap width being in the range of 250 to 2000 μm. The first doctor blade surface of the hollow blade has an edge (the front edge of the hollow blade, first edge) and the second doctor blade surface also has an edge, the trailing edge of the hollow blade, and the second edge. Based on the direction of movement of the hollow blade, the first edge is the while the second edge is the one following. The width of the gap formed between the first and second edge or between the leading edge and the trailing edge is usually 250 to 2000 μm, preferably approximately 500 μm. In the limited by the two edges cavity of the slurry is pumped. The hollow blade is connected to a pump, which builds up the necessary pressure to convey the slurry through the squeegee. The first and the second edge, respectively front and rear edge have different heights. The leading edge is a greater distance from the surface under the squeegee than the trailing edge. As a result, the slip is conveyed under the leading edge and a mountain slip forms in front of the leading edge. This Schlickerberg is pushed during the movement of the doctor blade over the application surface in front of the doctor blade - a bow wave comparable. The amount of slip in the Schlickerberg ensures a sufficient supply of slurry for the uniform layer application when moving the squeegee. The trailing edge of the squeegee determines the height of the respective slip layer applied during the movement of the squeegee, through its height to the surface or layer below the squeegee. Usually the layer height is between 50 and 200μm.

Against this background, the principle realized with the proposed layer application unit relates to a method which provides for the construction of a powder bed by means of the LSD technology, but has an improved doctoring and coating application technology beyond the prior art. The slip used here can be ceramic slip, for example silicate slip. Likewise suspensions of metallic particles can be used.

• 1 zeigt eine herkömmliche Hohlrakel im Querschnitt.
• 2 zeigt eine erste Ausführungsform der erfindungsgemäßen Auftragsvorrichtung (hier auch als Doppelrakel bezeichnet) im Querschnitt.
• 3 zeigt eine zweite Ausführungsform der erfindungsgemäßen Auftragsvorrichtung bzw. Doppelrakel im Querschnitt.
• 4 zeigt eine Aufsicht auf die hier vorgeschlagene Schichtauftragseinheit.

The accompanying drawings illustrate embodiments and, together with the description, serve to explain the principles of the invention. The elements of the drawings are relative to one another and not necessarily to scale. Like reference numerals designate corresponding parts accordingly.

• 1 shows a conventional hollow blade in cross section.
• 2 shows a first embodiment of the applicator device according to the invention (also referred to here as a double blade) in cross section.
• 3 shows a second embodiment of the applicator or double squeegee according to the invention in cross section.
• 4 shows a plan view of the proposed here layer application unit.

In particular shows 1 one from left to right on the application surface 6 moved hollow squeegee 1 comprising a first edge 2 or front edge 2 and a second edge 3 , or trailing edge 3 , The squeegee 1 transports the suspension used for coating, ie the slurry 4 , When moving the squeegee 1 during the shift order (in 1 from left to right) forms in front of the front edge 2 the squeegee 1 a slip mountain 5 off while the squeegee 1 over the application area 6 to be led. The slurry is continuously fed with a pump, so that during the shift job always a slip mountain is pushed in front of the squeegee. Preferably, the application surface is absorbent.

2 shows a first design of the applicator device proposed here 10 or layer application unit. This also transports the slip 4 , In contrast to the previously known squeegee 1 are the first edge 2 according to the leading edge 2 and the second edge 3 , according to the trailing edge 3 but both at the same distance from the absorbent application surface 6 arranged. As a result, in the case of the linear movement of the application device or the double doctor blade over the application surface, the slurry emerges in each case at that edge which lies behind the other edge in the direction of movement. The position of the leading edge and that of the following edge (tailing edge) thus results from the direction of movement of the applicator 10 or double squeegee 10 , At the edge in the direction of movement in front 2 In contrast to previously known doctor blades, it is no longer possible to form a slip mountain. The replenishment of the slurry takes place exclusively from the Schlickerreservoir the device 10 out and immediately beyond the typically wider slot here 30 , Typical gap widths a of the slot 30 be for example 1 mm to 2 cm. However, the slot can also be 100 mm wide. Preferably, a slot width a of 5 to 20mm. While the slot has the width a, the edges have a width b. According to the first design shown here, the width of the two edges b is less than the slot width a. The dosage of the slip 4 on the order surface 6 takes place at a typically constant hydrostatic pressure, which coincides with the accumulation height h of the slip in the application device or double doctor blade 10 results. Advantageously, the storage height h is adjustable to a constant value. For example, the layer application unit can be set up to allow a storage height of 10-100 mm, in particular to ensure an approximately constant filling level h of the slurry in the squeegee of 4 cm to 10 cm. The in the applicator or double squeegee 10 standing slip 4 (Liquid column of the suspension) thus ensures a continuous hydrostatic pressure at the gap above the application surface 6 , The presence of a vertical column of liquid and a constant hydrostatic pressure at the gap above the application surface is a typical feature of the applicator or double squeegee proposed here 10 , regardless of the type of construction. In contact with the absorbent application surface 6 sets under the applicator or double squeegee 10 the formation of a broken piece 7 on. In particular, the broken piece is under the slot and the rear edge of the applicator in the direction of movement 10 or double doctor blade formed.

So the slurry starts under the applicator or double squeegee 10 after contact with the absorbent application surface 6 , which may be, for example, a previously applied dry powder layer, with the body formation. Shard formation is proportional to the root of time. To contact the squeegee edges with the suspension 4 and not the shards 7 to ensure (for the definition of the layer height) and a collision of the applicator or double doctor blade 10 with the formed shards 7 To prevent the speed of the applicator or double squeegee 10 matched to the body formation rate of the slip. Among other things, the body formation rate depends on the particle size distribution of the powder in the slurry and its solids content. Furthermore, the body formation in the first layers is different due to the different absorbency of the absorbent application surface compared to a large number of already formed layers. The speed of the applicator or double doctor blade is therefore chosen so that the broken pieces 7 not yet grown to the entire layer height, while the applicator or double squeegee 10 over the application area 6 slides. If the body formation rate is very large, the applicator or double squeegee becomes 10 moves faster to collide with the broken pieces 7 to avoid. Typical speeds of the linear movement of the applicator or double squeegee 10 lie between 10 mm / s to 200 mm / s.

3 shows a second design of the proposed applicator or double doctor blade 10 , This also includes a standing liquid column of approximately constant height h. However, here the wall width b at the squeegee foot is greater than the slot width a. The same for both lower edges 2 and 3 (Brushing surfaces, faces) the same distance to the application surface 6 provides an always constant interaction distance between the opening 30 or the slip exit slot 30 the applicator 10 or double squeegee 10 and the application area 6 sicher.Typische distances, ie typical working distances between the doctor foot and the work surface are in the range of 20 to 1000 microns. For example, a preferred working distance may be 50 μm to 100 μm. At a given speed of movement of the applicator or double squeegee 10 results - as well as for the first design - a constant interaction time of the applicator or double doctor blade 10 provided suspension 4 with the application area 6 , The interaction duration and the absorbency of the application surface 6 for a given composition of slurry, define the formation of the shard 7 under the applicator or double squeegee 10 , A typical speed of the squeegee is 10 mm / s to 200 mm / s. During the movement of the applicator or double squeegee 10 over the application area 6 is at the slip exit slot 30 , ie at the slurry outlet opening 30 the applicator or double doctor blade 10 always new surface tracked, on the under formation of the broken pieces 7 the ready for subsequent consolidation powder layer is formed. According to a modification of this design, the applicator or double squeegee 10 also have a funnel shape in cross-section. The walls of the applicator or double squeegee 10 do not have to be parallel to each other. The slot typically has a rectangular shape when viewed from the application surface and has a width of 1 mm to 2 cm. However, the squeegee opening can also be up to 100 mm, as advantageous have widths of the squeegee opening a of 5 to 20 mm proved. The width b of the doctor blade wall on the doctor foot is typically 1 to 20 mm, preferably 2 to 5 mm.

4 shows a view of the proposed layer application unit. The applicator or double squeegee 10 becomes in a linear direction alternately from one side of the absorbent application surface 6 to the other side of the absorbent application surface 6 moved (see double arrow). The case not swept from the gap of the applicator, the absorbent application surface 6 surrounding edge surface is as a hydrophobic surface 8th educated. The edge surface is dense, non-absorbent, and constructed of or coated with hydrophobic material.

The proposed applicator or double squeegee 10 includes a first edge 2 , Front edge 2 and a second edge 3 , also trailing edge 3 called, both enclose a cavity, or a working volume and form a gap. In comparison to the commonly used hollow blade, however, this gap is wider. A typical width of the gap, ie a typical, over the lateral extent of the doctor blade constant distance between the first and second edge, ie between the leading edge 2 and trailing edge 3 the double blade is between 1 mm and 15 mm, preferably 5 to 20 mm. The double squeegee or applicator 10 can advantageously be filled without pressure, without a pump, with slip. The enclosed by the two spaced squeegee surfaces (blades) and two-sided side surfaces cavity of the Squeegee serves as a storage vessel or working volume for the slip 4 and provides enough slip for a homogeneous layer application of at least one layer. Refilling the applicator or double squeegee 10 may be carried out after the application of one or more layers, or preferably continuously. The geometry of the applicator or squeegee allows a transport of the slurry towards the gap, which is driven exclusively by gravity. As a result, during the movement of the application device or double doctor blade, the slip consumed in each case by the layer formation is replaced again directly beneath the application device or double doctor blade. This ensures a constant supply of the slip required for the layer application and enables a uniform layer application over the entire extent of the applicator or double doctor blade on the full width of the application surface. The time of interaction of the slurry directly fed with the squeegee and the absorbent application surface under the nip is determined at a constant speed of the squeegee by the width of the squeegee slot which defines the contact surface of the slurry with the sorbent application surface. Due to the capillary transport-driven withdrawal of the suspending agent, the body formation of the slip begins under the doctor blade, directly below the slip outlet slot. In other words, a powder layer with the typical packing density is formed from the slurry layer. The trailing edge and the leading edge of the proposed double doctor blade each have the same height above the application surface. In other words. The distance between a first edge (leading edge) of the double squeegee and the absorbent applicator surface equals the distance between the second edge (trailing edge) of the double squeegee and the absorbent applicator surface. The distance is for example in the range of 20 to 1000 microns. The double squeegee can thus apply slip in both directions at right angles to the leading edge and trailing edge of the double squeegee. The application device or double doctor blade moves in a movement in a first direction over the application surface and thereby contributes a first slip layer. This movement in the first direction ends above a parking station arranged at one end of the application surface 9 , The parking station 9 allows parking of the applicator 10 or double squeegee 10 during the consolidation step, and prevents slip from the slurry outlet (gap) 30 exit. The parking station 9 comprises a layer of spongy material or a gasket. The sponge or seal allows the applicator or double squeegee 10 to seal during parking.

The width b of the doctor wall at the foot of the applicator or double doctor blade 10 can be carried out differently to allow for different viscosities at the respective hydrostatic pressure (filling level) improved sealing of the applicator or double doctor in the parking position. Applicators or double squeegee with walls having any angle (eg, parallel or funnel shape) and spacers are also possible. Likewise, designs of the applicator or double squeegee are possible, which provide a different amount of slurry in the double squeegee at the same level h. Likewise, designs are possible by different ratios of the width a of the opening 30 the applicator or double squeegee to fill level h have.

A solids content of typically used slip is in the range of 40-80% by volume. The viscosity of the slurry is in the range of 0.1 to 5 Pa s.

According to a preferred embodiment, an application surface has in each case two parking stations, so that each movement of the application device or double squeegee ends over the application surface on a parking station. While the application device or double doctor blade is located at a parking station, a consolidation step typically follows. After the consolidation step, the work surface is lowered by the respective process-typical amount, for example by 100 μm, and the subsequent layer is applied. For this purpose, the applicator or double squeegee is now moved in the opposite direction.

The parking station allows the applicator to be parked during the consolidation step, with no slip flowing further to the side. For this purpose, the doctor blade is driven on a sponge-like material or a seal, which makes it possible to seal the applicator or doctor blade. Different embodiments of the double squeegee or applicator are possible: The squeegee wall on the squeegee b can be made in different widths, so that at different viscosities and different hydrostatic pressure complete sealing of the applicator or double squeegee in the parking position is possible. Applicators or double squeegee with walls having any angle (eg parallel or funnel shape) and spacers to vary at the same level h, the amount of slurry in the enclosed by the applicator or double squeegee working volume and with different ratios of the width of the Opening the doctor blade a, to the filling height h, are also possible from typically 1 to 1 to 1 to 100.

According to a modified embodiment of the proposed method, the Consolidation step also take place only after the successive application of two layers.

The second layer is thus applied by a change in the direction of movement of the doctor blade in a direction opposite to the second direction extending second direction, after the work surface has been lowered by the method typically selected value. In this way, for example, a 100 micron thick layer of two 50 micron thick layers can be generated.

Throughout the process, the applicator is held at a constant height above the application surface. Typically, the build platform is lowered by a motor by the layer thickness (for example by 100 microns), while the applicator remains fixed in height. Alternatively, a height-adjustable applicator or double squeegee and a fixed in height construction platform (application surface) can be combined.

In addition, the absorbent application surface 6 from a hydrophobic surface 8th surround. This prevents an order of the suspension next to the application surface.

In contrast to known LSD processes, slip transport in the proposed application device or double squeegee takes place without pressure. He is driven exclusively by the absorbent base and gravitation. The slip is thereby transported to the slot arranged above the application surface (i.e., the lower edge of the applicator or double squeegee). This leads to a non-pressurized, constant provision of the slurry under the applicator or double doctor blade for the uniform coating order. The body formation starts below the application device or double squeegee and not in a Schlickerberg forming in front of the squeegee. The interaction time of the slurry with the absorbent application surface is defined by the squeegee and not by the Schlickerberg in front of the squeegee. The proposed applicator or double squeegee can apply slip in both directions at right angles to the leading edge and trailing edge of the double squeegee. The application process is characterized by an absorbent pad circumferentially surrounded by a nonabsorbent, hydrophobic edge.

Due to the device and process features described, the time of interaction (interaction time) of the slurry with the absorbent substrate is better defined than heretofore and thus adjustable to a preferred value.

Since the applicator or double squeegee can now apply slip in two directions, an unused path to the starting point is eliminated, which advantageously allows the accelerated buildup of the layer stack.

By eliminating the time otherwise required for the return to the starting point of the shift order no drying of slurry on the doctor blade takes place. Thus, no cleaning of the applicator or double squeegee before the order of a follow-up layer is more necessary.

Advantageously, further, a loss of material during the construction of a layer stack can be avoided because no mountain slip is pushed in front of the squeegee, which is pushed down at the end of the application surface as excess slip from the construction area and so lost.

The squeegee no longer has to travel a useless path over the construction area. This eliminates the risk of contamination of the construction area by drops falling from the double squeegee. Further eliminates the need for a pump due to the pressure-free Schlickerförderung, due to the design-related wider slot in the applicator or double doctor blade.

The following explanation shall serve for the method of constructing a slip layer or a piece broken with the applicator or double squeegee described:

The slip begins under the applicator or double squeegee after contact with the absorbent pad, or a previously applied dry layer, with pitting. Shard formation is proportional to the root of time. In order to ensure a contact of the doctor blade edges with the suspension and not the shard (for the definition of the layer height) and to prevent a collision of the applicator or double doctor blade with the formed shards, the speed of the applicator or double doctor blade on the body formation rate of the slip Voted. Among other things, the body formation rate depends on the particle size distribution of the powder in the slurry and the solids content of the slurry. The speed of the applicator or double doctor blade is selected so that the cullet is not yet grown on the entire layer height, while the applicator or double squeegee is above the relevant section of the application surface. If the body formation rate is very high, the application device or double doctor blade is moved faster in order to avoid a collision with the body. Typical movement speeds are 10 mm / s - 200 mm / s. The described applicator or double doctor blade is advantageously moved by means of a linear motor.

In the normal case, the build platform is lowered by a motor by the layer thickness, typically by 100 .mu.m, while the applicator or doctor blade remains fixed in height. In the case of very large superstructures, which can become very heavy, a height-adjustable applicator or double squeegee and a mounting platform (application surface) fixed in height are advantageous instead. The lowering of the build platform can be done, for example, with a linear motor or with a stepper motor.

The absorbency of the application surface or the previously applied layers and the rate of advancement of the applicator or double doctor blade influence the collision-free layer application. Under a collision-free layer order is understood that no contact of the moving applicator or double doctor blade with freshly formed cullet takes place.

A high body formation rate means little time until the shards have formed over the entire layer height, this results in the requirement of a high speed of movement of the applicator or double doctor blade, for example, between 100 mm / s to 200 mm / s.

A low shard formation rate means more time until the shards have formed over the entire layer height and allows a low rate of progress, for example in the range of 10 mm / s to 50 mm / s. If a large layer thickness, be achieved from about 150 to 200 microns, so more time is required until the shards has formed over the entire layer height. This also means a lower speed of movement of the applicator or double doctor blade, for example in the range of 10 mm / s to 50 mm / s.

1. 1. Schichtauftrag einer Suspension keramischer und/oder metallischer Partikel auf eine saugfähige Unterlage mit definierter Wechselwirkungszeit von Suspension und Unterlage über die Breite eines Schlitzes.
2. 2. Rakel mit zwei gleichhohen Kanten, die in einem konstanten Abstand zu einer saugfähigen Auftragsfläche über diese saugfähige Auftragsfläche gefahren wird.
3. 3. Als Schlitz in einer Rakel ausgeführtes Schlickerreservoir.
4. 4. Verwendung der Rakel zur Herstellung von Pulverschichten hoher Packungsdichte.

The present invention may be briefly summarized with the following points:

1. 1. coating a suspension of ceramic and / or metallic particles on an absorbent pad with a defined interaction time of suspension and pad across the width of a slot.
2. 2. Squeegee with two equal high edges, which is driven at a constant distance to an absorbent application surface on this absorbent application surface.
3. 3. Schlickerreservoir designed as a slot in a squeegee.
4. 4. Use of the doctor blade for the production of powder layers of high packing density.

An alternative description of the claimed invention is the following:

Applicator device ( 10 ) for the additive manufacturing comprising a working volume for receiving a coating material, wherein the working volume is at least laterally enclosed by a wall and a bottom surface with an in the bottom surface arranged and substantially rectangular opening ( 30 ) having.

1. 1. Schlickerauftragseinheit umfassend eine Doppelrakel 10 und eine Auftragsfläche 6 für den Auftrag einer Folge von Schichten eines Schlickers 4 auf der Auftragsfläche 6, wobei die Doppelrakel 10 eine erste Rakelkante 2 und eine zweite Rakelkante 3 umfasst, welche einander gegenüberliegenden Längsseiten eines Schlickeraustrittsschlitzes 30 entsprechen, wobei ein Abstand der ersten Rakelkante 2 zur zweiten Rakelkante 3 eine Breite eines Schlickeraustrittsschlitzes 30 definiert, und die Doppelrakel 10 so über der Auftragsfläche 6 anordenbar ist, dass ein erster Arbeitsspalt zwischen der ersten Rakelkante 2 und der Auftragsfläche 6 identisch ist mit einem zweiten Arbeitsspalt zwischen der zweiten Rakelkante 3 und der Auftragsfläche 6, sodass mit einer Bewegung der Doppelrakel 10 über die Auftragsfläche 6 hinweg in einer zum Schlickeraustrittsschlitz 30 rechtwinkligen Bewegungsrichtung 20 und unabhängig von einer Richtung der Bewegung aus einem durch den Schlickeraustrittsschlitz 30 bereitstellbaren Schlicker 4 eine Schlickerschicht konstanter Schichtdicke ausschließlich im zweiten Arbeitsspalt formbar ist, indem der am Schlickeraustrittsschlitz 30 bereitstellbare Schlicker 4 den zweiten Arbeitsspalt füllt, ohne dabei den ersten Arbeitsspalt zu benetzen, wobei der erste Arbeitsspalt derjenige ist, welcher entlang der Bewegungsrichtung 20 vorn liegt, und wobei der zweite Arbeitsspalt derjenige ist, der in Bewegungsrichtung 20 hinten liegt.
2. 2. Schlickerauftragseinheit nach Aspekt 1, weiter umfassend eine die Auftragsfläche (6) umgebende Randfläche 8.
3. 3. Schlickerauftragseinheit nach einem der vorstehenden Aspekte, wobei die Randfläche 8 hydrophob ist.
4. 4. Schlickerauftragseinheit nach einem der vorstehenden Aspekte, wobei die Auftragsfläche 6 saugfähig für ein Suspensionsmittel des Schlickers 4 ist.
5. 5. Schlickerauftragseinheit nach einem der vorstehenden Aspekte, wobei die Auftragsfläche 6 ausgewählt ist unter einer Arbeitsbühne oder unter einer oberen Pulverschicht eines auf der Arbeitsbühne angeordneten Schichtstapels.
6. 6. Schlickerauftragseinheit nach einem der vorstehenden Aspekte, weiter umfassend zumindest eine auf der Randfläche 8 angeordnete Parkstation 9 für die Doppelrakel 10, wobei die Parkstation 9 eine Dichtungsfläche und/oder eine Schwammfläche umfasst und wobei eine flächige Ausdehnung der Parkstation 9 auf der Randfläche 8 zumindest einer Größe des Schlickeraustrittschlitzes 30 der Doppelrakel 10 gleicht, sodass ein Austreten des Schlickers 4 aus dem Schlickeraustrittschlitz 30 der Doppelrakel 10 verhinderbar ist.
7. 7. Schlickerauftragseinheit nach einem der vorstehenden Aspekte, wobei eine sich in einer Richtung der Bewegung der Doppelrakel 10 über die Auftragsfläche 6 hinweg erstreckende Breite der Parkstation 9 zumindest gleich oder größer ist als eine Summe, gebildet aus der Breite a des Schlickeraustrittsschlitzes und einem zweifachen Wert der Rakelkantenbreite b.
8. 8. Schlickerauftragseinheit nach einem der vorstehenden Aspekte, wobei ein Scherben 7 formbar ist, ohne dass während der Bewegung der Doppelrakel 10 über die Auftragsfläche 6 hinweg ein Schlickerberg 5 vor der Doppelrakel 10 ausgebildet wird.
9. 9. Schlickerauftragseinheit nach einem der vorstehenden Aspekte, wobei die Breite a des Schlickeraustrittschlitzes 30 zwischen 0,2 mm und 20 mm, bevorzugt zwischen 1 mm und 20 mm, weiter bevorzugt zwischen 5 bis 15 mm beträgt.
10. 10. Verfahren zum Schichtauftrag für die schlickerbasierte additive Fertigung, umfassend:
    • - Bereitstellen einer Schlickerauftragseinheit nach einem der Aspekte 1 bis 9;
    • - Anordnen der Doppelrakel 10 auf einer Parkstation 9;
    • - Befüllen eines Arbeitsvolumens der Doppelrakel 10 mit einem Schlicker 4;
    • - Bewegen der mit Schlicker 4 befüllten Doppelrakel 10 entlang einer Bewegungsrichtung 20 über die Auftragsfläche 6 mit einer konstanten Geschwindigkeit in einer Längsrichtung der Auftragsfläche 6 unter Einhalten eines konstanten Arbeitsabstands zwischen einer vorderen Querschnittsebene der Schlickeraustrittsöffnung 30 und der Auftragsfläche 6;
    • - Anordnen der Schlickerauftragseinheit auf einer zweiten Parkstation 9, wobei die zweite Parkstation 9 an einer der ersten Parkstation 9 gegenüberliegenden Seite der Auftragsfläche 6 auf einer die Auftragsfläche 6 umgebenden Randfläche 8 angeordnet ist,
    sodass während des Bewegens der mit Schlicker 4 befüllten Doppelrakel 10 eine Scherben 7 einer konstanten Schichthöhe auf der Auftragsfläche 6 ausgebildet wird.
11. 11. Verfahren nach Aspekt 10, wobei eine Viskosität des Schlickers in einem Bereich von 0,1 Pa s - 5 Pa s liegt.
12. 12. Verfahren nach einem der Aspekte 10 oder 11, wobei ein Feststoffgehalt des Schlickers 4 zwischen 40 bis 80 Volumen-% beträgt.
13. 13. Verfahren nach einem der Aspekte 10 bis 12, wobei das Bewegen der mit Schlicker 4 befüllten Doppelrakel 10 über die Auftragsfläche 8 mit einer Geschwindigkeit von 10 mm/s bis 200 mm/s, bevorzugt mit einer Geschwindigkeit von 10 bis 100 mm/s, insbesondere von 50 bis 100 mm/s erfolgt.
14. 14. Verfahren nach einem der Aspekte 10 bis 13, wobei der Arbeitsabstand einem gemeinsamen Abstand zwischen der Auftragsfläche 6 zu einer ersten Rakelkante 2 der Doppelrakel 10 und zu einer zweiten Rakelkante 3 der Doppelrakel 10 entspricht und im Bereich von 20 bis 300 µm, bevorzugt im Bereich von 50 µm bis 100 µm liegt.
15. 15. Verfahren nach einem der Aspekte 10 bis 14, wobei beim Bewegen der Doppelrakel 10 über die Auftragsfläche 6 der Scherben 7 jeweils zumindest teilweise unter derjenigen Kante 3, 2 der Doppelrakel 10 ausgebildet wird, die in einer Richtung der Bewegung der Doppelrakel 10 hinter der in Bewegungsrichtung 20 vorn liegenden Kante 2, 3 der Doppelrakel 10 liegt, während die in Bewegungsrichtung 20 vorn liegende Kante 2, 3 bevorzug nicht vom Schlicker 4 benetzt wird.

The aspects of the present invention are thus:

1. 1. slip application unit comprising a double squeegee 10 and an order surface 6 for the order of a succession of layers of a slip 4 on the order surface 6 , where the double squeegee 10 a first squeegee edge 2 and a second squeegee edge 3 includes which opposite longitudinal sides of a Schlickeraustrittsschlitzes 30 correspond, wherein a distance of the first doctor edge 2 to the second squeegee edge 3 a width of a slip exit slot 30 defined, and the double squeegee 10 so above the order surface 6 can be arranged that a first working gap between the first blade edge 2 and the application area 6 is identical to a second working gap between the second doctor edge 3 and the application area 6 so with a movement of the double squeegee 10 over the application area 6 away in a slip exit slot 30 right-angled direction of movement 20 and regardless of a direction of movement from one through the slurry exit slot 30 Provable slip 4 a slurry layer of constant layer thickness can be formed only in the second working gap by the slurry exit slot 30 Provable slip 4 fills the second working gap without wetting the first working gap, wherein the first working gap is the one which along the direction of movement 20 is at the front, and wherein the second working gap is the one in the direction of movement 20 lies behind.
2. 2. slip application unit according to aspect 1 , further comprising an order surface ( 6 ) surrounding edge surface 8th ,
3. 3. slip application unit according to one of the preceding aspects, wherein the edge surface 8th is hydrophobic.
4. 4. slip application unit according to one of the preceding aspects, wherein the application surface 6 absorbent for a suspension agent of the slip 4 is.
5. 5. slip application unit according to one of the preceding aspects, wherein the application surface 6 is selected under a work platform or under an upper powder layer of a stack of layers arranged on the work platform.
6. 6. slip application unit according to one of the preceding aspects, further comprising at least one on the edge surface 8th arranged parking station 9 for the double squeegee 10 , where the parking station 9 a sealing surface and / or a sponge surface comprises and wherein a planar extension of the parking station 9 on the edge surface 8th at least one size of Schlickeraustrittschlitzes 30 the double squeegee 10 is similar, allowing leakage of the slip 4 from the slip exit slot 30 the double squeegee 10 is preventable.
7. 7. slip application unit according to one of the preceding aspects, wherein one in a direction of movement of the double squeegee 10 over the application area 6 extending width of the parking station 9 is at least equal to or greater than a sum formed from the width a of the slurry exit slot and a double value of the doctor edge width b.
8. 8. slip application unit according to one of the preceding aspects, wherein a broken piece 7 is malleable without the double squeegee during movement 10 over the application area 6 away a slip mountain 5 in front of the double squeegee 10 is trained.
9. 9. slip application unit according to one of the preceding aspects, wherein the width a of the Schlickeraustrittschlitzes 30 between 0.2 mm and 20 mm, preferably between 1 mm and 20 mm, more preferably between 5 to 15 mm.
10. 10. A method of applying a layer for slip-based additive manufacturing, comprising:
    • - Providing a slip application unit according to one of the aspects 1 to 9 ;
    • - Arrange the double squeegee 10 on a parking station 9 ;
    • - filling a working volume of the double squeegee 10 with a slip 4 ;
    • - Move the with slip 4 filled double squeegee 10 along a direction of movement 20 over the application area 6 at a constant speed in a longitudinal direction of the application surface 6 while maintaining a constant working distance between a front cross-sectional plane of Schlickeraustrittsöffnung 30 and the application area 6 ;
    • - Arranging the slip application unit on a second parking station 9 , wherein the second parking station 9 at one of the first parking station 9 opposite side of the application surface 6 on one the order surface 6 surrounding edge surface 8th is arranged
    so while moving with the slip 4 filled double squeegee 10 a piece of broken glass 7 a constant layer height on the application surface 6 is trained.
11. 11. Method according to aspect 10 , wherein a viscosity of the slurry is in a range of 0.1 Pa s - 5 Pa s.
12. 12. Method according to one of the aspects 10 or 11 , wherein a solids content of the slip 4 between 40 to 80% by volume.
13. 13. Method according to one of the aspects 10 to 12 , moving with the slip 4 filled double squeegee 10 over the application area 8th at a speed of 10 mm / s to 200 mm / s, preferably at a speed of 10 to 100 mm / s, in particular from 50 to 100 mm / s.
14. 14. Method according to one of the aspects 10 to 13 , where the working distance is a common distance between the application surface 6 to a first blade edge 2 the double squeegee 10 and to a second squeegee edge 3 the double squeegee 10 corresponds to and is in the range of 20 to 300 microns, preferably in the range of 50 microns to 100 microns.
15. 15. Method according to one of the aspects 10 to 14 , wherein when moving the double squeegee 10 over the application area 6 the broken pieces 7 each at least partially under that edge 3 . 2 the double squeegee 10 is formed in a direction of movement of the double squeegee 10 behind in the direction of movement 20 forward edge 2 . 3 the double squeegee 10 lies while moving in the direction 20 leading edge 2 . 3 do not prefer the slip 4 is wetted.

While specific embodiments have been illustrated and described herein, it is within the scope of the present invention to properly modify the illustrated embodiments without departing from the scope of the present invention. The following claims are a first, non-binding attempt to broadly define the invention.

LIST OF REFERENCE NUMBERS

1

hollow knife

10

Applicator, double squeegee

2

first edge, leading edge, leading edge in the direction of movement

20

movement direction

3

second edge, trailing edge, edge lying in the direction of movement

30

essentially rectangular opening, slip outlet opening, slip exit slot

4

Application material, suspension, slip

5

Schlickerberg

6

Application area, if necessary absorbent

7

shards

8th

Edge surface, possibly hydrophobic

9

parking Lot

Claims (10)

Slip application unit comprising: - An application device (10) for additive manufacturing, adapted for at least one predetermined rectilinear movement direction (20) during application of a slurry (4), comprising a working volume for receiving the slurry (4), wherein the working volume at least laterally enclosed by a wall is, and has a bottom surface with a substantially rectangular opening (30) arranged in the bottom surface, the long sides of the substantially rectangular opening (30) extending in an orthogonal direction to the rectilinear moving direction (20) and the edges defining the long sides having identical distances to a plane defined by the direction of movement (20); and - An application surface (6), wherein the application device (10) is arranged above the application surface (6), so that a distance between the bottom surface and the application surface (6) in a linear movement of the applicator in a long side of the substantially rectangular Opening (30) orthogonal direction of movement (20) is adjustable to a constant value, wherein the application surface (6) comprises a surrounding edge surface (8), wherein the edge surface (8) comprises at least one parking station (9) for the application device (10), and the parking station (9) is arranged, the substantially rectangular opening (8). 30) in the bottom surface of the application device (10) so that no slip (4) can escape from the working volume through the substantially rectangular opening (30), if a viscosity of the slip in a range of 0.1 Pa s - 5 Pa s is located. Slip application unit according to Claim 1 , wherein the constant value of the distance is between 20 microns and 1000 microns. Slip application unit according to Claim 1 or 2 further comprising a linear motor for moving the applicator over the application surface (6). Slip application unit according to Claim 1 , wherein the edge surface (8) is hydrophobic. Method for layer application for slip-based additive manufacturing, comprising: - providing a slip application unit according to one of Claims 1 to 4 ; - Arranging the applicator device (10) on a first parking station (9); - filling a working volume of the application device (10) with a slurry (4), wherein a viscosity of the slurry is in a range of 0.1 Pa s - 5 Pa s; Moving the application device (10) filled with the slurry (4) along a direction of movement (20) over the application surface (6) at a constant speed in a longitudinal direction of the application surface (6) while maintaining a constant working distance between the substantially rectangular opening (FIG. 30) of the application device (10) and the application surface (6); - Arranging the applicator device (10) on a second parking station (9), wherein the second parking station (9) on one of the first parking station (9) opposite side of the application surface (6) on the application surface (6) surrounding edge surface (8) is, wherein the first and the second parking station (9) are arranged to close the rectangular opening (30) in the bottom surface of the application device (10) so that no slip (4) can escape, so that during movement with the slurry ( 4) filled applicator (10), a broken piece (7) of a constant layer height on the application surface (6) is formed. Method according to Claim 5 wherein a solids content of the slip (4) is between 40 and 80% by volume. Method according to one of Claims 5 or 6 wherein the moving of the application device (10) filled with slurry (4) over the application surface (6) takes place at a speed selected from: 10 mm / s to 200 mm / s, 10 to 100 mm / s, and 50 up to 100 mm / s. Method according to one of Claims 5 to 7 , wherein the working distance corresponds to a common distance between the application surface (6) to a forward edge (2) of the applicator (10) and to a rear edge (3) of the applicator (10) in the direction of movement and in a range of 20 to 300 microns, preferably in the range of 50 microns to 100 microns. Method according to one of Claims 5 to 8th , Wherein, when moving the applicator (10) over the application surface (6) of the shards (7) each at least partially under that edge (3, 2) of the Applicator (10) is formed, which in a direction of movement of the applicator (10) behind the front in the direction of movement (20) edge (2, 3) of the applicator (10), while in the direction of movement (20) leading edge (2, 3) is not wetted by the slip (4). Method according to one of Claims 5 to 9 wherein the first and second parking stations (9) are identical, and moving the applicator (10) filled with the slurry (4) comprises changing the direction of movement and moving the applicator (10) in two opposite directions.

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