WO2019091709A1

WO2019091709A1 - Slurry application unit and method for layer application for slurry-based additive production

Info

Publication number: WO2019091709A1
Application number: PCT/EP2018/078220
Authority: WO
Inventors: Jens GÜNSTER; Andrea ZOCCA; Jörg Lüchtenborg
Original assignee: Bundesrepublik Deutschland, Vertreten Durch Die Bundesministerin Für Wirtschaft Und Energie, Diese Vertreten Durch Den Präsidenten Der Bundesanstalt Für Materialforschung Und -Prüfung (Bam)
Priority date: 2017-11-09
Filing date: 2018-10-16
Publication date: 2019-05-16
Also published as: DE102017126274B4; DE102017126274A1

Abstract

The invention relates to an application device (10) for additive production, designed for at least one predetermined, linear direction of movement (20) during an applying of an application material (4), comprising a working volume for receiving the application material (4), wherein the working volume is enclosed at least laterally by a wall, and a base surface having an opening (30), which is arranged in the base surface and is substantially rectangular, wherein the long sides of the substantially rectangular opening (30) extend in an orthogonal direction relative to the linear direction of movement (20) and the edges defining the long sides have identical distances to a plane, which is defined by the direction of movement (20).

Description

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

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

The 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 by means of a flowable powder or a suspension with

subsequent drying can be applied. 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 (layerwise sludge deposition), the structure of a powder layer by the application of a ceramic suspension (slurry) 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, the layer order due to the doctor blade technology only by a

Movement of the squeegee made from one side of the job 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.

Against this background, an application device according to claim 1 is proposed. Further embodiments, modifications, and improvements will become apparent from the following description of the appended claims and the attached drawings. According to one embodiment, an application device for additive manufacturing is proposed, which is set up for at least one predetermined rectilinear movement direction during application of a job 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 a

Has bottom surface with an arranged in the bottom surface and substantially rectangular opening. 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.

Advantageously, when applying the application material with the applicator described the entire material emerging from the opening material 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

Application device when moving in two different directions apply a layer on the application surface. Thus, the effectiveness of the layer structure over previously known types is significantly increased.

According to one embodiment of the applicator, a distance between long sides of the substantially rectangular opening of 1 mm to 100 mm, preferably from 1 mm to 20 mm.

The layer formation is uniform over the entire width of the applicator. 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 one embodiment, the substantially rectangular opening comprises the entire bottom surface of the working volume.

Advantageously, the slip 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 heights of the

Application material, e.g. of a slip to provide in the working volume.

According to another embodiment, a long side of the arranged in the bottom surface rectangular opening 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.

According to a further embodiment, a slip application unit comprising an application device described above by way of example and an application surface, wherein the application device can be arranged above the application surface that a distance between the bottom surface and the application surface in a linear movement of the

Applicator can be set in a direction orthogonal to the long side of the substantially rectangular opening direction of movement to a constant value.

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 also no loss of order material occurs by pushing this Schlickerberg of the

Application area 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 one embodiment of the aforementioned slip application unit, the constant value of the distance between the bottom surface of the applicator and the application surface of 20 μιη to 1000 μιη.

Advantageously, the reasonably smooth outer contours of a green body produced allows. According to a further embodiment, the slip application unit further comprises a linear motor for moving the applicator device over the application surface.

Advantageously, a linear motor to different desired

Progress speeds of the order unit are adjusted over the order surface.

According to a further embodiment, the application surface comprises a surrounding edge surface.

Advantageously, the edge surface 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 here is filed. In addition, the distance of the edge surface independent of the working surface relative to

Adjustment device set and with the aim of little material to be minimized. In this context, distances smaller than 10 μm are advantageous.

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

Advantageously, the wettability of the hydrophobic edge surface with the

Application material, so the slip, greatly reduced. Preferably, the typically aqueous slip does not wet the edge surface at all.

According to a further embodiment, the edge surface comprises at least one parking station for the applicator and the parking station is arranged so that the substantially rectangular opening in the bottom surface of the applicator is closed during parking of the applicator on the parking station so that no

Application material from the working volume can escape through the substantially rectangular opening.

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

The embodiments described above can be combined with each other as desired. 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.

The essential features of these methods are the creation of

Process control data from CAD geometry data with subsequent control of

Processing devices. All of these methods share the following features:

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 powdery starting material instead.

2: All methods build part geometries of layers of finite thickness, which are realized by a slice process, directly from CAD data.

The methods available today differ in the

Initial state of the materials (solid, liquid, pasty) during the layer addition or the building 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 process is described in US 6,827,988 B2. 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.

The high packing densities of the powder particles in the powder bed result in the powder bed forming a free-standing block enclosing the component. In the LSD process, suspensions of ceramic or metallic particles (hereafter called slips) are used to build powder layers with a high packing density of the powder particles, and to stack 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 unit. Subsequently, the powder particles are locally consolidated by laser sintering or injection of a binder.

In the previous LSD technology, the slurry is applied via a hollow blade. The hollow blade comprises a gap in an elongated hollow doctor blade, wherein the gap width is in the range of 250 to 2000 μιη. 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 leading edge, while the second edge is that which follows. 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 about 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 is determined by the height of the squeegee

surface or layer, the height of each applied slip layer.

Usually, the layer height is between 50 and 200μιη.

Against this background, this relates to the proposed

Layer application unit realized principle a method which provides the structure of a powder bed by means of the LSD technology, but in addition to the state of the art has an improved doctor blade and layer application technology. The ones used here Slips can be ceramic slips, for example silicate slips. Likewise suspensions of metallic particles can be used.

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.

FIG. 1 shows a conventional hollow blade in cross section.

FIG. 2 shows a first embodiment of the invention

Application device (also referred to here as a double blade) in cross section.

FIG. 3 shows a second embodiment of the invention

Applicator or double squeegee in cross section.

FIG. 4 shows a plan view of the layer application unit proposed here.

In particular, Fig. 1 shows a moving from left to right on the application surface 6 hollow doctor blade 1, comprising a first edge 2 and front edge 2 and a second edge 3, or trailing edge 3. The doctor 1 transports the used for coating order Suspension, ie the slurry 4. During the movement of the doctor blade 1 during the

Layer application (in Fig. 1 from left to right) is formed in front of the front edge 2 of the doctor blade 1 from a slip 5, while the doctor blade 1 is guided over the application surface 6. The slurry is continuously fed with a pump, so during the

Shift job always a Schlickerberg is pushed in front of the squeegee. Preferably, the application surface is absorbent.

FIG. 2 shows a first design of the applicator device 10 or layer application unit proposed here. This also transports the slurry 4. In contrast to the prior art doctor blade 1, the first edge 2 corresponding to the leading edge 2 and the second edge 3, but according to the trailing edge 3 are both arranged at the same distance from the absorbent application surface 6. 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 (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. An each in the direction of movement at the front edge 2 can train in contrast to prior art squeegees no Schlickerberg more. The replenishment of the slurry takes place exclusively from the Schlickerreservoir the device 10 and directly over the here typically wider slot 30. Typical gap widths a of the slot 30, 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 metering of the slurry 4 onto the application surface 6 takes place at a typically constant hydrostatic pressure, which results with the accumulation height h of the slurry in the application device or double doctor blade 10. 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 slurry 4 (liquid column of the suspension) standing in the application device or double doctor blade 10 thus ensures a continuous hydrostatic pressure at the gap above the application surface 6. The presence of a stationary liquid column and a constant hydrostatic pressure at the gap above the application surface is a typical feature of the present invention proposed applicator or double doctor blade 10, regardless of the particular design. In contact with the absorbent application surface 6 sets under the applicator or double doctor blade 10, the formation of a piece of broken glass 7 a. In particular, the broken pieces under the slot and the in

Direction of movement of the rear edge of the applicator 10 or double doctor blade formed.

The slurry thus begins under the applicator or double doctor blade 10 after contact with the absorbent application surface 6, which may be, for example, a previously applied dry powder layer, with the body formation. The

Shard formation is proportional to the root of time. To contact the

Squeegee edges with the suspension 4 and not the shard 7 to make sure (for the

Definition of the layer height) and to prevent a collision of the applicator or double doctor blade 10 with the formed cullet 7, the speed of

Applicator or double doctor blade 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 Shards 7 has not yet grown to the entire layer height, while the

Applicator or double squeegee 10 slides over the application surface 6. Is the

Shard formation rate very large, the applicator or double doctor blade 10 is moved faster to avoid collision with the body 7. Typical speeds of the linear movement of the applicator or double doctor blade 10 are between 10 mm / s to 200 mm / s.

3 shows a second design of the proposed application device or double squeegee 10. This also comprises 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 distance for the lower surface 2 and 3 (strike surfaces, end faces), which is also the same here for the application surface 6, always ensures a constant interaction distance between the opening 30 and the slip exit slot 30 of the application device 10 or

Double doctor blade 10 and the application surface 6 sicher.Typisch distances, i. typical

Arbeitsab states between the doctor foot and the work surface are in the range of 20 to 1000 μιη. For example, a preferred working distance may be 50 μιη to 100 μιη. At a given speed of movement of the applicator or double doctor blade 10 results - as well as for the first design - a constant interaction effective time provided by the applicator or double doctor blade 10 suspension 4 with the

Application surface 6. The interaction duration and the absorbency of the application surface 6 define, for a given composition of the slurry, the formation of the body 7 beneath 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 doctor blade 10 on the application surface 6 is on

Slip exit slot 30, i. at the slip outlet opening 30 of the applicator or double squeegee 10 always new surface tracked on the formation of the cullet 7 which is prepared for subsequent consolidation powder layer is formed. According to a modification of this design, the applicator or double doctor blade 10 may also have a funnel shape in cross-section. The walls of the applicator or double doctor blade 10 need not be arranged 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 have proven advantageous widths of the squeegee opening a from 5 to 20 mm. The width b of the doctor blade wall on the doctor foot is typically 1 to 20 mm, preferably 2 to 5 mm.

FIG. 4 shows a plan view of the proposed layer application unit. The applicator or double doctor blade 10 is alternately in a linear direction of a Side of the absorbent application surface 6 to the other side of the absorbent application surface 6 moves (see double arrow). The edge surface which is not swept by the gap of the application device and which surrounds the absorbent application surface 6 is designed as a hydrophobic surface 8. The edge surface is dense, non-absorbent, and constructed of or coated with hydrophobic material.

The proposed applicator or double doctor blade 10 thus includes a first edge 2, front edge 2 and a second edge 3, also called trailing edge 3, 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, i. a typical constant distance between the first and second edge over the lateral extent of the doctor blade, i. between the leading edge 2 and trailing edge 3 of the double squeegee is between 1 mm and 15 mm, preferably 5 to 20 mm. The double doctor blade or applicator 10 can advantageously be filled without pressure, without a pump, with slip. The space enclosed by the two spaced doctor blade surfaces (blades) and two-sided side surfaces cavity of the squeegee serves as a storage vessel or working volume for the slurry 4 and provides enough slip for a homogeneous coating order at least one layer ready. A refilling of the application device or double doctor blade 10 can 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 directly under the application device or

Double squeegee replaced again. This ensures a constant supply of the

Layer order required slip and allows a uniform coating order 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 leading edge of the proposed Double squeegees are each the same height above the application area. In other words. The distance between a first edge (leading edge) of the double squeegee and the absorbent application surface is equal to the distance between the second edge (trailing edge) of the

Double squeegee and the absorbent application surface. The distance is for example in the range of 20 to 1000 μιη. 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 9 arranged at one end of the application surface. The parking station 9 permits parking of the application device 10 or double squeegee 10 during the parking

Consolidation step, and prevents slip out of the slurry outlet opening (gap) 30 emerges. The parking station 9 comprises a layer of sponge-like material or a gasket. The sponge or seal makes it possible to seal the application device or double doctor blade 10 during parking.

The width b of the doctor wall at the foot of the applicator or double doctor blade 10 can be made different to allow for different viscosities at the respective hydrostatic pressure (level) improved sealing of the applicator or double doctor in the parking position. Applicators or double squeegees with walls having any angle (e.g., parallel or funnel shape) and spacers are also possible. Likewise, types of the applicator device or

Double squeegee possible that provide a different amount of slip in the double squeegee at the same level h. Likewise, designs are possible which have different ratios of the width a of the opening 30 of the application device or double squeegee, to the filling level h.

A solids content of typically used slip is in the range of 40-80 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 in each case has 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 squeegee is located at a parking station, typically includes a

Consolidation step. After the consolidation step, the work surface is lowered by the respective process-typical amount, for example by 100 μιη and the applied subsequent layer. For this purpose, the applicator or double squeegee is now moved in the opposite direction.

The parking station allows the applicator device to be parked during the consolidation step without any 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 versions of the

Double squeegee or the 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. Application devices or

Double squeegee with walls which have any angle (eg parallel or funnel shape) and widenings to vary the amount of slurry in the working volume enclosed by the applicator or double squeegee at the same level h and with different ratios of the width of the squeegee opening a, to the filling level 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 can 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 typical method selected value. In this way, for example, a 100 μιη thick layer of two 50 μιη thick partial layers are generated.

Throughout the process, the applicator device is maintained at a constant height above the application surface. Typically, the build platform is lowered by a motor by the layer thickness (for example, by ΙΟΟμιη), while the

Application device remains fixed in height. Alternatively, a height-adjustable applicator or double squeegee and a fixed in height construction platform

(Order surface) can be combined.

In addition, the absorbent application surface 6 is surrounded by a hydrophobic surface 8. This prevents an order of the suspension next to the application surface. In contrast to known LSD method, the Schlickertransport takes place without pressure in the proposed applicator or double doctor blade. He is driven exclusively by the absorbent base and gravitation. The slurry is thereby to the arranged on the application surface slot (ie the lower edges of the

Applicator or double squeegee) transported. This leads to a non-pressurized, constant provision of the slurry under the applicator or double doctor blade for the uniform coating order. The shards begin below the

Applicator or double squeegee and not in a form before the squeegee Schlickerberg. 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 device 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 method is characterized by an absorbent pad, which is circumferentially surrounded by a non-absorbent, hydrophobic edge.

By the device and process features described, the time of interaction (interaction time) of the slurry with the absorbent surface 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, eliminating an unused path to the starting point, which advantageously allows the accelerated structure of the layer stack.

By eliminating the otherwise for the way back to the starting point of the

Shift job required time does not take place drying of slurry on the doctor blade. Thus, no cleaning of the applicator or double squeegee before the order of a follow-up layer is more necessary.

Advantageously, furthermore, a loss of material during the construction of a layer stack can be avoided because no mountain slip is pushed in front of the doctor, 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. Furthermore, omitted by a non-pressurized Schlickerförderung, due to the design-related wider slot in the applicator or double doctor blade the requirement of a pump.

To that described with the application device or double squeegee

executable method of building a slip layer or a piece of broken glass is to serve the following explanation:

The slurry begins under the applicator or double blade after contact with the absorbent pad, or a previously applied dry layer, with the body formation. Shard formation is proportional to the root of time. In order to ensure contact of the squeegee edges with the suspension and not the shard (for the definition of the layer height) and a collision of the

To prevent applicator or double doctor blade with the formed cullet, the speed of the applicator or double doctor blade is tuned to the body formation rate of the slip. The shard rate depends, among others, on the

Grain size distribution of the powder in the slurry and the solids content of the slurry from. The speed of the applicator or double doctor blade is chosen so that the body has not yet grown to the entire layer height, while the

Applicator or double squeegee is located above the relevant section of the application surface. If the body formation rate is very high, the application device or

Double squeegee moved faster to avoid collision with the broken piece. 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 ΙΟΟμιη, 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. Lowering the

Build-up platform can, for example, be made 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 with the moving application device or

Double squeegee with freshly formed shards 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

Progress speed, for example in the range of 10 mm / s to 50 mm / s. If a large layer thickness, for example from 150 to 200 μm, is to be achieved, then more time is required until the body 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.

The present invention can be scarce with the following points

be summarized:

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. Doctor with two equal edges, which is driven at a constant distance to an absorbent application surface on this absorbent application surface.

3. Schlickerreservoir designed as a slot in a doctor blade.

4. Use of the doctor blade for producing powder layers higher

Packing density.

An alternative description of the claimed invention is the following:

An application device (10) for additive manufacturing comprising

Working volume for receiving a job material, the volume of work at least is enclosed laterally by a wall and a bottom surface with a in the

Having bottom surface arranged and substantially rectangular opening (30).

The aspects of the present invention are thus:

1. slip application unit comprising a double doctor blade 10 and an application surface 6 for the application of a sequence of layers of a slurry 4 on the application surface 6, wherein the double doctor blade 10 comprises a first blade edge 2 and a second blade edge 3, which opposite longitudinal sides of a

Schlickeraustrittsschlitzes 30 correspond, wherein a distance of the first doctor blade edge 2 to the second blade edge 3 defines a width of Schlickeraustrittsschlitzes 30, and the double doctor blade 10 can be arranged above the application surface 6, that a first working gap between the first doctor edge 2 and the application surface 6 is identical to a second working gap between the second blade edge 3 and the

Application area 6, so that with a movement of the double squeegee 10 over the

Application surface 6 away in a direction perpendicular to Schlickeraustrittsschlitz 30 movement direction 20 and regardless of a direction of movement of a slidable through the Schlickeraustrittsschlitz 30 Schlicker 4 a

Slip layer of constant layer thickness can be formed exclusively in the second working gap by the slip 4 which can be provided at the slip exit slot 30 fills the second working gap without wetting the first working gap, the first working gap being the one which lies forward along the direction of movement 20, and the second working gap Working gap is the one that lies behind in the direction of movement 20.

2. slip application unit according to aspect 1, further comprising an edge surface 8 surrounding the application surface (6).

3. slip application unit according to one of the preceding aspects, wherein the edge surface 8 is hydrophobic.

4. slip application unit according to one of the preceding aspects, wherein the

Application surface 6 is absorbent for a suspending agent of the slurry 4. A slurry application unit according to any one of the preceding aspects, wherein the

Application surface 6 is selected under a working platform or under an upper powder layer of a layer stack arranged on the working platform.

Slip application unit according to one of the preceding aspects, further comprising at least one arranged on the edge surface 8 parking station 9 for the double doctor blade 10, wherein the parking station 9 comprises a sealing surface and / or a sponge surface and wherein a planar extension of the parking station 9 on the edge surface 8 at least one size the Schlickeraustrittschlitzes 30 of the double doctor blade 10 is equal, so that leakage of the slurry 4 from the Schlickeraustrittschlitz 30 of

Double squeegee 10 is preventable. A slip application unit according to any one of the preceding aspects, wherein a width of the parking station 9 extending in a direction of movement of the double doctor blade 10 across the application surface 6 is at least equal to or greater than a sum formed by the width a of the slip exit slot and twice the doctor blade edge width b. A slurry application unit according to any one of the preceding aspects, wherein a sheet 7 is malleable without causing the double blade 10 to overflow during movement

Application surface 6 away a slip mountain 5 is formed in front of the double doctor blade 10. A slip application unit according to any one of the preceding aspects, wherein the width a of the slip slit slit 30 is between 0.2 mm and 20 mm, preferably between 1 mm and 20 mm, more preferably between 5 and 15 mm. Method for layer application for slip-based additive manufacturing, comprising:

Providing a slip application unit according to one of the aspects

1 to 9;

Arranging the double doctor blade 10 on a parking station 9;

Filling a working volume of the double doctor blade 10 with a slurry 4;

Moving the filled with Schlicker 4 double doctor blade 10 along a

Movement direction 20 over the application surface 6 with 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 the slurry outlet opening 30 and the application surface 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 a the order surface 6 surrounding

Edge surface 8 is arranged so that a broken pieces 7 of a constant layer height is formed on the application surface 6 during the movement of the double blade 10 filled with slurry 4.

11. A method according to aspect 10, wherein a viscosity of the slurry is in a range of 0.1 Pa s - 5 Pa s.

12. The method according to any one of aspects 10 or 11, wherein a solids content of

Schlickers 4 is between 40 and 80% by volume.

13. The method according to any one of aspects 10 to 12, wherein the moving of the double blade 10 filled with slurry 4 over the application surface 8 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. The method according to any one of aspects 10 to 13, wherein the working distance a

common distance between the application surface 6 to a first doctor blade edge 2 of the double doctor blade 10 and a second blade edge 3 of the double doctor blade 10 and in the range of 20 to 300 μιη, preferably in the range of 50 μιη to 100 μιη.

15. The method according to any one of aspects 10 to 14, wherein when moving the double doctor blade 10 over the application surface 6 of the sherds 7 is at least partially formed under that edge 3, 2 of the double doctor blade 10 in a direction of movement of the double doctor blade 10 behind the lying in the direction of movement 20 forward edge 2, 3 of the double doctor blade 10, while the forward in the direction of movement 20 edge 2, 3 Favor is not wetted by the slip 4.

While specific embodiments have been illustrated and described herein, it is within the scope of the present invention to use those shown Modify embodiments appropriately 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 blade

10 application device, double squeegee

2 first edge, leading edge, forward edge 20 in the direction of movement

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

30 substantially rectangular opening,

Slip exit opening, slip exit slot

4 application material, suspension, slip

5 Schlickerberg

6 application area, if necessary absorbent

7 shards

8 edge surface, possibly hydrophobic

9 parking area

Claims

claims

An applicator (10) for additive manufacturing, arranged for at least one predetermined rectilinear movement direction (20) during application of an application material (4), comprising: a working volume for receiving the application material (4), wherein the working volume at least laterally from a wall is enclosed, and has a bottom surface with 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 the long sides defining edges have identical distances to a plane defined by the direction of movement (20).

The application device (10) according to claim 1, wherein a distance between long sides of the substantially rectangular opening (30) is 1 mm to 100 mm, preferably 1 mm to 20 mm.

3. application device (10) according to any one of claims 1 or 2, wherein the im

Essentially rectangular opening (30) the entire floor surface of the

Working volume has.

4. application device (10) according to one of claims 1 to 3, wherein a height of the wall, measured from the bottom surface, is at least 50 mm.

5. An applicator device (10) according to any one of claims 1 to 4, wherein a long side of the arranged in the bottom surface rectangular opening (30) is at least 10 mm, typically at least 200 mm.

A slip application unit comprising an application device (10) according to any one of claims 1 to 5 and an application surface (6), wherein the application device (10) is arranged above the application surface (6), so that a distance between the

Floor area and the application area

(6) in a linear motion of

Application device in a direction of the long side of the substantially rectangular opening (30) orthogonal movement direction (20) is adjustable to a constant value.

7. slip application unit according to claim 6, wherein the constant value of the distance between 20 μιη and 1000 μιη.

8. slip application unit according to claim 6 or 7, further comprising a linear motor for moving the applicator device over the application surface (6).

9. slip application unit according to one of claims 6 to 8, wherein the application surface (6) comprises an application surface (6) surrounding edge surface (8).

10. slip application unit according to claim 9, wherein the edge surface (8) is hydrophobic.

11. slip application unit according to one of claims 9 or 10, wherein the edge surface (8) at least one parking station (9) for the application device (10), and the parking station (9) is arranged, the substantially rectangular opening (30) in the Bottom surface of the applicator device (10) to close so that no

Application material from the working volume through the substantially rectangular opening (30) can escape.