EP3837105A1

EP3837105A1 - Closure device, 3d printing device and method for producing 3d mouldings

Info

Publication number: EP3837105A1
Application number: EP19765964.2A
Authority: EP
Inventors: Josef Grasegger; Bastian HEYMEL; Wolfgang MÜHLBAUER
Original assignee: Voxeljet AG
Current assignee: Voxeljet AG
Priority date: 2018-08-16
Filing date: 2019-08-15
Publication date: 2021-06-23
Also published as: US20210316507A1; WO2020035100A1; DE102018006473A1

Abstract

Closure device suitable for a 3D printing device and/or coater device, comprising a closure means (500), wherein the closure means is activatable and can be opened by activating means, wherein the activating means is an eccentric, a draw key and/or a slotted link (501). The invention also relates to a method and a device for producing 3D mouldings, wherein such a closure device is used.

Description

LOCKING DEVICE, 3D PRINTING DEVICE AND

METHOD FOR PRODUCING 3D MOLDED PARTS

The invention relates to a method and an apparatus for producing three-dimensional models by means of layer construction technology.

The European patent EP 0 431 924 B1 describes a method for producing three-dimensional objects from computer data. A thin layer of a particulate material is applied to a platform and this is selectively printed with a binder material using a print head. The particle area printed with the binder adheres and solidifies under the influence of the binder and, if necessary, an additional hardener. The platform is then lowered into a construction cylinder by a layer thickness and provided with a new layer of particle material which is also printed, as described above. These steps are repeated until a certain desired height of the object is reached. A three-dimensional object is created from the printed and solidified areas.

This object, which is made of solidified particle material, is embedded in loose particle material after its completion and is then freed from it. This is done, for example, by means of a sucker. All that remains are the desired objects, which are then removed from the residual powder e.g. can be freed by brushing.

An important step is the powder application. Correct dosing and targeted and controlled application of the powder material are important here. The coater speed or the

1

CONFIRMATION COPY The speed at which the particle material can be applied has a considerable influence on the manufacturing time of the components and thus on the economy of the machine used.

For better metering of the powder material, coaters can, for example, have an adjustable opening, often in the form of a gap. This gap can, for example, extend over a large part of the width of the coater.

A problem with known coaters using an adjustable slot or opening is that the gap size or the gap opening has to be enlarged in order to be able to dispense a larger quantity of particulate material. This may influence the controllability of the particle exit, because it can happen that the gap or slit can no longer be controlled, since particle material emerges even at a standstill.

This problem occurs in particular in the case of coaters which close the gap or slot by means of pouring cones and open them by means of a vibration and thus control the particle material outlet.

Examples of this are so-called oscillating blade coaters as described in DE10117875A1 or DE10216013A1.

In order to be able to form a pouring cone for closing in a large opening of the coater, the coater blade would have to be designed in dimensions that would be structurally problematic, since the usable coater dimensions would then make the construction site size uneconomical. In particular, a very long coater blade would have to be used in order to be able to build up a pouring cone which can cause the gap to close. However, a large-sized coater blade would reduce the buildable space and thus reduce economy. Another problem is the start-up speed or the delay in the gap opening of oscillating blade coater openings closed by pouring cone due to vibration and the associated quality problems due to insufficient

Particulate material application. The problem here is that the coater is moved or started at a certain speed. The coater travels a certain distance above the construction site, while the vibration in the vibrating blade coater causes the cone closure to collapse and particle material to flow out. However, it can happen that the particulate matter begins to flow out too late and that insufficient particulate matter is applied to a certain part of the construction site. As a result, it can result in either too little volume of particle material or no particle material being applied in certain areas of the construction field in this time window.

It was therefore an object of the present invention to provide constructive means which permit an improved 3D printing process or at least improve or completely avoid the disadvantages of the prior art.

Another object of the present invention was to modify a coater in such a way that a large amount of particulate material can be applied from a coater to the construction platform and at the same time the gap opening of the coater can be completely closed and the coater can still be moved at high speed can, in order to achieve advantageous and / or shortened manufacturing times.

A further object of the present invention was therefore to provide a method, a material system and / or a device which helps to reduce the disadvantages of the prior art or avoids or prevents them entirely. Brief summary of the invention

In one aspect, the invention relates to a closure device suitable for a 3D printing device and / or coating device, comprising a controllable closure means.

In a further aspect, the invention relates to a 3D printing device which comprises a controllable closure means.

In a further aspect, the invention relates to a method for producing 3D shaped parts, wherein particulate building material is applied in a defined layer by means of a coater to a construction field, is selectively solidified in order to obtain a 3D shaped part, the coater including a closure device, which comprises a controllable closure means.

Brief description of the figures

FIG. 1 a shows an aspect of the disclosure, wherein a coating container 105 with particle material 101 is shown. The coater blade 102 faces the building platform (not shown) and, with the adjustable diaphragm 103 (closure means), forms a coater gap 100 in which a pouring cone made of particle material 104 is formed to close the gap. The adjustable diaphragm 103 can be controlled by suitable means and the coater gap 100 can thus be opened further. In this way, for example, an increased amount of particulate material can be applied to the building platform (not shown) and the traveling speed of the coater can thus be increased. If the coater gap is to be closed again, the diaphragm 103 is actuated and the coater gap is reduced, so that a pouring cone can form again as soon as the oscillation of the coater blade 102 is set. FIG. 1b shows the process of applying the particulate material, the coater being moved in the feed movement 108. The coater blade 102 (see FIG. 1 a) is set in vibration with a swinging movement 109, so that the pouring cone opens and particle material flows out and a roller made of particle material 107 is formed and an applied layer of particle material 106 is applied.

2 describes another aspect of the disclosure.

2a shows a coater container 105 filled with particle material 101 and coater blade 102 and adjustable diaphragm 103 with closure plate 201 and control roller 200. In this position of the closure plate 201, no particle material can emerge from the gap.

In FIG. 2b, the control roller 200 is actuated and the closure plate 201 is moved in a direction 203 by rotation, and the coating container is thus opened, so that the outflowing particulate material 204 forms a powder roller and a particulate material layer

Driving over the coater over the build platform is formed on the build platform.

3a and 3b describe another aspect of the disclosure.

A coating container 105 with particle material 101 is shown, as is the closure device, which has an elongated blade 302, an adjustable diaphragm 103, prestressed closure plate 301,

Closure seal 300 and control roller 200 includes.

Fig. 4 describes another aspect of the disclosure, wherein the control, i.e. opening and closing the opening by means of

Sealing plate 201, is carried out by driving with a backdrop.

In Fig. 4a the gap is closed and in Fig. 4b the closure plate 201 is folded or moved in parallel and thus the gap of the coating container is opened. Here, a ball 400 is moved in the backdrop. FIG. 5 describes a further aspect of the disclosure, FIG. 5a showing a closed gap and FIG. 5b an open gap of the coating container. Here, a vertically movable diaphragm 500 and a horizontally movable backdrop 501 are used. 502 shows the cylinder connected to the diaphragm and 503 the link guide and 504 the link movement.

FIG. 6 describes a further aspect of the disclosure, wherein a simplified flow diagram for a double coater system is shown with the outflows of the controlled (active - according to the invention) and the non-controlled (passive - prior art) coater. It is clear that a larger volume can be applied to the construction platform with the closure system according to the invention.

Detailed description of the invention

According to the invention, an object on which the application is based is achieved in that a closure device is provided which is completely lockable and can release increased amounts of particulate material after start-up and can apply it to the building platform.

Some terms of the invention are first explained in more detail below.

“3D molded part”, “molded body” or “component” in the sense of the invention are all three-dimensional objects produced by means of the method according to the invention and / or the device according to the invention, which have a dimensional stability.

"Construction space" is the geometrical place in which the particle material bed grows during the construction process by repeated coating with particle material or through which the bed material passes in continuous principles Construction level, limited, with continuous principles usually exist Conveyor belt and delimiting side walls. The installation space can also be configured by a so-called job box, which represents a unit that can be extended and retracted into the device and allows batch production, a job box being extended after the process has ended and a new job box being able to be inserted into the device immediately, so that Manufacturing volume and thus the device performance is increased.

“Construction platform” or “construction field” in the sense of the disclosure is the area to which the particle material is applied and on which the particle material is selectively solidified in order to build up a predetermined three-dimensional molded part.

All materials known for powder-based 3D printing, in particular polymers, ceramics and metals, can be used as “particle materials” or “particulate building materials” or “building materials”. The particle material is preferably a dry, free-flowing powder, but it can also be a cohesive one cut-resistant powder or a particle-laden liquid are used. In this document, particle material and powder are used synonymously.

"Particle material application" is the process in which a defined layer of powder is generated. This can be done either on the construction platform or on an inclined plane relative to a conveyor belt using continuous principles. The particle material application is also referred to as "coating" or "recoating". called.

In the sense of the invention, “selective application of liquid” can take place after each application of particulate material or, depending on the requirements of the shaped body and for optimizing the manufacture of the shaped body, can also be carried out irregularly, for example several times with respect to an application of particulate material.

Any known 3D printing device can be used as the "device" for carrying out the method according to the invention required components. Common components include coater, construction field, means for moving the construction field or other components in continuous processes, dosing devices and heat and / or radiation means and other components known to the person skilled in the art, which are therefore not described in detail here.

“Closure device” or “closure unit” in the sense of the disclosure combines the positive features that can be achieved with a swinging blade construction and at the same time allows the coating device to be started up more quickly and larger particle material volumes to be applied. Such a "locking device" comprises or includes at least one oscillating blade and a locking means which can be controlled by suitable means, for example by means of an eccentric, a pulling wedge and / or a link.

The "packing density" describes the filling of the geometric space by a solid. It depends on the nature of the particle material and the application device and is an important starting variable for the sintering process.

The building material is always applied in a "defined layer" or "layer thickness", which is set individually depending on the building material and process conditions. It is, for example, 0.05 to 0.5 mm, preferably 0.1 to 0.3 mm.

“Gap” or “gap opening” in the sense of the disclosure means the agent through which particle material is applied from the recoater or onto the construction platform and by means of which the application amount of particle material can be controlled. The particle material emerges from the coater through the “gap” or the “gap opening” and flows onto the construction platform. The "closure" or "coater closure" controls the released amount of particulate material. A “coating blade” or “oscillating blade” in the sense of the disclosure relates to a means of a coating device facing the building platform, which means can be combined with other means to control the application of particulate material. The "coater blade" can form a gap with another part or means of the coater device, which is closed at standstill by a pouring cone. In the present disclosure, the "coater blade" is closed and opened with a controllable closure, for example a spring steel sheet, and so on Particle material application controlled on the construction site.

A “closure device” in the sense of the disclosure relates to the combination of coater blade, controllable closure and actuator in a particle material coater.

A “closure means” or “closure” or “coater closure” in the sense of the disclosure is a means that enables the gap of the coater to be closed and opened in a controlled manner. It can be, for example, a spring steel sheet.

A “control means” or “actuator” in the sense of the disclosure serves to open and close the closure means.

“Opening speed” in the sense of the disclosure means the length of time that passes until the closure means is actuated from its closed position to its maximum opening.

"Closure opening process" in the sense of the disclosure is the process in which the closure means is brought from its closed to its open position. Accordingly, a "closure closing process" is the reverse process.

“Travel speed” in the sense of the disclosure refers to the speed of the coater moving forwards or backwards. The travel speed and the opening speed are important variables, the process sequence, the production speed for 3D molded parts and the control of the start-up and the printing process influence. These variables therefore also influence the economy of a 3D printing device.

The aspects of the invention are described below.

In one aspect, the invention relates to a closure device suitable for a 3D printing device and / or coating device, comprising a closure means, preferably a steel sheet, for example spring steel sheet, the closure means being controllable and being able to be opened by a control means, the control means being an eccentric, is a pull wedge and / or a backdrop.

A particularly advantageous solution was provided with the method according to the invention in order to solve the problem on which the application is based.

With the inventive closure system and coater, it becomes possible to increase the powder throughput or the particle material application of the coater and thereby to achieve higher travel speeds and to increase the application speed and the application volume per unit of time.

With the device components shown above in the combination shown, very advantageous process results could surprisingly be achieved.

With the device according to the invention, the problems or disadvantages set out above are at least reduced or avoided entirely.

The closure device described here can be installed in 3D printing devices and / or coating devices that use and apply fluid, particulate material to build up the layer and build up the 3D molded parts. The coater can be a simple powder coater or a double coater. The closure device can contain a control means which serves to open the closure means, for example a steel spring plate, and / or to control the gap width (gap size). A closure device thus has at least one closure means, a coater blade and a particle material supply or a particle material container, the parts being connected to one another in such a way that an application to a construction site can take place in a controlled manner. The control means can open the closure means from 1 to 5 mm.

With the closure device, it is also possible to control the opening speed and to apply particulate material to the building platform in a targeted manner. The speed required to achieve a maximum opening of the closure means. The opening speed (maximum opening of the gap) can be from 0.5 / 10 to 3/10 seconds, preferably from 1/10 to 2/10 seconds.

With the coater and / or closure as described here, it is advantageously possible not only to better control not only the application quantity but also the start-up speed for dispensing particulate material. Furthermore, the problem of missing particle material application when starting up the coater can be avoided, which results in quality advantages in the components. This also increases profitability, since the scrap is reduced.

Furthermore, in known coaters, there will always be a large amount of waste particle material which cannot be recycled or can only be recycled with increased effort and the associated costs. With the coater or closure as described herein, these disadvantages of the prior art can be avoided or at least reduced. A closure as described here also facilitates the gradual arrangement of coaters as described in detail below.

In conventional vibratory coaters, the outflow can only be adjusted by mechanically adjusting the gap outside the process, while the device according to the invention enables the gap to be adjusted and even regulated during operation.

The closure device can be installed in a coater which has a coater opening in the direction of travel. It can essentially be an oscillating blade recoater as described in the prior art described above. It can also be a double coater which has an oscillating blade opening in each direction of travel and with which particle material can thus be applied to the construction field in both directions of travel.

In a further aspect, the disclosure relates to a 3D printing device and / or a coater device comprising a closure means as described above, the distance covered by the coater device when starting up or while driving over the construction field from the beginning of the closure opening process until the closure 2 opens cm to 10 cm, preferably 3 cm to 7 cm, with a travel speed of the coating device or the closure device of 350 mm / second.

The 3D printing device and / or coater device described here can comprise: a closure device as described above and a coater blade as described above.

The coater blade can be made of all suitable materials and preferably consists of a stainless steel sheet. The coater blade can be set in vibration by any means known to those skilled in the art. The vibration is generated using one or more eccentrics, for example.

In the 3D printing device and / or coating device described here, the powder material (particle material) can be released by means of a combination of the closing device described here and a vibration of the coating blade. This advantageously realizes the advantages of a vibrating blade coater and avoids the disadvantages of particle material volumes that can be applied to a limited extent.

The coater can be closed by covering the gap as well as by changing the pouring cone in the gap by changing the aspect ratio (i.e. the ratio of gap height to gap length) of the gap by suitable measures, preferably reducing the gap height by moving the screen.

In a further embodiment, the disclosure relates to a method for producing 3D molded parts, wherein a closure device or 3D printing device or as described above

Coating device is used.

Known printheads with suitable technology are used to apply the pressure fluid. The liquid can be selectively applied using one or more print heads. The drop mass of the print head or print heads is preferably adjustable. The print head or print heads can selectively apply the liquid in one or both directions of travel. In the process it is achieved that the particulate building material is selectively solidified, preferably selectively solidified and sintered.

During the construction process, building material and hydraulic fluid are applied cyclically. The construction site is lowered by the selected layer thickness or the application units are raised accordingly. These processes are repeated cyclically.

A closure as described here is particularly advantageous in combination with the method described below and / or the device arrangement and is characterized by various advantages:

The closure described above is combined with a method for producing three-dimensional models by means of a layer construction technique, particle-shaped construction material being applied in a defined layer to a construction field and a binder liquid being selectively applied to the construction material, a certain amount being moved and these steps being repeated, until the desired object is created, the application and application steps taking place substantially simultaneously.

The method as described above is characterized in that the particulate building material is applied with a coater and / or the binder liquid is applied with a printhead.

The method as described above can be characterized in that the device means printhead follows the device means coater at a defined distance, preferably at a distance of 1000 mm - 300 mm, more preferably 300 mm - 50 mm, even more preferably immediately , Furthermore, in the method as described above, the device means can be moved at a speed of 0.02 m / s to 1 m / s, preferably that the different device means are moved at the same or a different speed.

In one embodiment, the method as described above is characterized in that the device means are retracted and the device means returns in rapid traverse, preferably at a speed of 0.5 m / s to 5 m / s.

Another method, as described above, is characterized in that the application and the application take place in the forward and in the return.

The material application can be controlled particularly advantageously by the closure as described above, which has a positive effect on the process sequence and on the quality of the parts produced in this way.

Another method as described above is characterized in that several device means of the coater and metering unit, preferably each 2 to 20, more preferably 4 to 15, form several layers in one pass.

The method as described above can be characterized in that several device means form several layers in one pass both in the forward and in the return, preferably it is characterized in that several device means build up several layers on a continuously operating conveyor unit. The process as described above can also be characterized in that an oblique printing process, a batch process and / or a continuous process is used as the basic process.

Furthermore, the closure as described above can advantageously be combined in a device for producing three-dimensional models by means of a layer construction technique, the at least two, preferably 3 to 20, pressure means at least two, preferably 2 to 20,

Coating means arranged downstream, preferably which has at least two coating means and at least two pressure means, preferably which is characterized in that the pressure medium and the coating means are arranged on the same axis, preferably which is characterized in that the pressure medium is designed as a linehead, preferably that is characterized in that the pressure medium and the coating means can be moved at a speed of 0.02 m / s to 5 m / s, preferably which is characterized in that the pressure medium and the coating means so are arranged and designed so that they can work in the forward and in the return, preferably which is characterized in that the pressure medium and the coating means are adjustable in different planes, preferably in their height, preferably in the Z axis , preferably which is characterized in that the pressure medium (s) and the coater (s) are arranged offset, preferably that they are arranged such that they can apply and apply a plurality of layers one above the other, preferably which is characterized in that it has a continuously operating conveyor unit, preferably which is characterized in that it is a diagonal printer , a batch printer or a continuously operating printer, preferably which is characterized in that it is designed as an inclined printer or / and the device means are arranged in a vertical carousel or wheel-like. In one embodiment, the inventors were able not only to significantly increase a volume output with a satisfactory quality level, but also to make it even more controllable using a combination of methods and devices with the closure described above.

The parallelization of the processes of coating and printing described here can be controlled even more precisely by means of the closure described above. The various printing processes are carried out essentially simultaneously and can advantageously be controlled very precisely by using the closure described above, it being possible to arrange a plurality of coaters and printing units in succession and to deposit and selectively solidify several layers in one pass. This does not require increases in travel speeds or other measures that negatively affect the quality of the products produced.

LIST OF REFERENCE NUMBERS

Beschichterspalt

Particle material

application blade

adjustable aperture

Particle material cone

Beschichterbehälter

applied layer of particle material

(Cone limited) roller made of particle material feed movement

Swinging motion of the blade control roller

Sealing sheet

Control roller rotation

Movement of the locking plate

outflowing particle material sealing gasket

pre-tensioned closing plate

extended blade bullet

operating slide

Backdrop in the bezel vertically movable aperture

horizontally movable backdrop with cylinder connected to the aperture backdrop guide

setting movement

Claims

claims

1. Locking device suitable for a 3D printing device and / or coating device, comprising a locking means, preferably a spring steel sheet, wherein the locking means can be controlled and opened by a control means, the control means being an eccentric, a pulling wedge and / or a link.

2. Closure device according to claim 1, wherein the coating device is a powder coater, preferably a double coater.

3. Closure device according to claim 1 or 2, wherein the closure means can be opened by the control means of 1 to 5 mm in its maximum opening width.

4. Closure device according to claim 1, 2 or 3, wherein the

Opening speed (maximum opening) is from 0.5 / 10 to 3/10 seconds, preferably from 1/10 to 2/10 seconds.

5. 3D printing device and / or coating device, comprising a closure means according to one of claims 1 to 4, wherein the distance traveled by the coating device from the beginning of the closure opening process to the opening of the closure 2 cm to 10 cm, preferably 3 cm to 7 cm, at a travel speed of the coating device or the closure device of 350 mm / second.

6. 3D printing device and / or coater according to claim

5, comprising a closure device according to one of claims 1 to 4 and a coater blade.

7. 3D printing device and / or coating device according to claim

6, powder material using a combination of Closure device according to one of claims 1 to 4 and a vibration of the coater blade can be released.

8. A method for producing 3D molded parts, wherein a closure device according to one of claims 1 to 4 or a 3D printing device and / or coating device according to claim 5 is used.