DE102020104633B4 - Carrier device for receiving a print head, additive manufacturing system and method for changing a print head on a carrier device - Google Patents

Abstract

Carrier device for receiving a print head for an additive manufacturing system for producing three-dimensional molded bodies, wherein the carrier device (1) has at least one carrier plate (2) which has at least one through opening in which the print head (3) can be at least partially arranged, wherein the print head (3) can be at least partially arranged on the carrier device (1), and wherein the carrier plate (2) further has at least one clamping unit for locking and/or clamping the print head (3) to the carrier plate (2), which is arranged concentrically to the opening and is designed as a rotatable bayonet catch (9), and the bayonet catch (9) has at least two projections extending radially to the center of the opening.

Description

An automatic tool changer for an additive manufacturing system is disclosed. A carrier device for holding a print head for an additive manufacturing system for producing three-dimensional molded bodies, an additive manufacturing system with at least one carrier device and a method for changing a print head on a carrier device in an additive manufacturing system are described.

background

There are currently additive manufacturing systems, commonly known as 3D printers or 3D printing systems, that have a print head and can only process one material with it. The corresponding material is applied layer by layer to a print bed - also called a build platform - and a three-dimensional molded body is created in the layer structure. In order to be able to produce objects that are made of different materials and therefore have different properties, it is necessary to be able to exchange these different materials during the manufacturing or printing process. In most cases, the material for 3D printing is available as filament. This filament is fed by an extruder into a so-called hot end, where it is melted and applied to the print bed or the object to be printed via a print nozzle.

Printing objects three-dimensionally with different materials opens up new possibilities for 3D printing technology in terms of design and mechanical properties. It is therefore very useful to be able to process different materials in one printing process.

State of the art

One way to change the material is to change the filament to be printed at the hot end. EN 10 2018 002 287 A1 describes, for example, a device that carries out an automatic filament change on a hot end, whereby the old filament is separated and a new filament is automatically inserted into the hot end. This procedure basically enables the processing of different materials during a 3D printing process. However, there are some disadvantages. First, the old, separated filament must be removed from the hot end. During this time, 3D printing is not possible. After the old filament has been removed from the hot end, the new filament is inserted. In order to be able to continue printing, however, sufficient pressure must first be built up in the print nozzle, which in turn costs time. Furthermore, it cannot be ruled out that residues of the old filament will be flushed out with the new filament. For this purpose, an object is usually printed on a certain spot on the print bed to be thrown away later, which only serves the purpose of cleaning the print nozzle. Another disadvantage arises from the different material properties that the different filaments can have, which in turn requires different print settings, calibrations and possibly different print nozzle geometries. In addition, the situation can arise that the old filament has a lower melting point than the new filament when changing. For example, the melting point of the old filament can be 200 °C and that of the new filament 250 °C. As already described, it cannot be ruled out that old filament is still present in the hot end when the new filament is inserted. If the filament is now heated to the higher melting point of the new filament, the old filament can decompose - in the case of a polymer, the decomposition of polymer chains - because its melting temperature is far exceeded. The decomposition products of the old filament can clog the hot end and the print nozzle.

Another option is to change the print head itself, which is already equipped with the corresponding material or filament. This approach initially leaves the disadvantages of changing the filament behind. There are various concepts for changing the print head. US 2019/0351617 A1 describes a 3D printer that has an effector in the form of a carrier device on which various print heads are arranged like a revolver. To change the material, the carrier device is rotated so that the print head with the corresponding material is brought into the printing position. The disadvantage here, however, is that all print heads must always be carried by the carrier device. This means that more mass has to be moved during the printing process, which has a negative effect on the positioning accuracy of the carrier device. In the worst case, this means that the tolerances with regard to the exact, specified printing position can be too large. It also means that the carrier device with the print heads moves more slowly, which also slows down the printing process overall.

In WO 2019/151147 A1 Another concept is described for printing different materials. It consists in the different print heads being arranged in a disk-shaped tool changer. Instead of the print head, the Print bed under the respective print head so that material can be applied to the print bed layer by layer. To change the material, the tool changer is rotated until the corresponding print head is in the printing position. The disadvantage here is the fact that the entire print bed, including the printed object, is moved three-dimensionally for the printing process. Weight is also a limiting factor here. More weight to be moved has a negative effect on positioning accuracy and printing speed. In addition, the travel speed of the print bed cannot be set arbitrarily high, as the object on the print bed may be moved from its original position or distorted by high acceleration forces. In the worst case scenario, the object slides off the print bed or tips over.

In the CN 2 04 997 998 U describes a 3D printer that can automatically replace a print head. The 3D printer has, among other things, a print head set that includes at least two print heads that are locked into place on a frame, and a lifting mechanism with a clamp seat, whereby the clamp seat can be moved by the lifting mechanism. To change the print head, the lifting mechanism can move the clamp seat under a print head and pick up and fix the respective print head from below. The print head is fixed to the clamp seat using a magnet. The disadvantage here is that a magnetic fixation does not represent a positive connection and thus possible slipping of the print head cannot be ruled out. Slipping would at least lead to a poor print result. Also, precise positioning based purely on magnetic forces is not nearly as precise as with, for example, positive locking. In addition, the magnetic forces can also act on other ferromagnetic components of the 3D printer, which can lead to undesirable attractions.

US 2016 / 0 136 893 A1 discloses a 3D printer which comprises a material shelf in which several material tubes can be accommodated. The material tubes in turn each have a pair of wings with which the material tube can be hung in corresponding positioning recesses. The print module of the 3D printer also has such positioning recesses. This allows the print module to pick up a material tube from the material shelf by means of a corresponding maneuver of the print module. The disadvantage here is that the material tube is only hung in. It hangs loosely over the pair of wings in the corresponding positioning recesses. It is not protected against slipping or jumping out. In the worst case, the object to be printed can be destroyed as a result.

The AT 518 789 A4 describes a device for the generative production of a molded body. Essentially, a 3D printer is disclosed which, among other things, has a positionable carrier for at least one push button, a positioning system for the carrier and an exchangeable unit with a print head, which has a receptacle for a material supply and a feed device for feeding material from a material supply to the print head. The print head can be fed to the carrier from the exchangeable unit via a gripper arm. For this purpose, the carrier approaches the print head, which is in a transfer position, from below. As a result, the print head is indirectly inserted into the intended print head receptacle of the carrier. Alignment and fixing takes place by means of a magnetic field of an electromagnet. The same disadvantages arise here that already existed with CN 2 04 997 998 U Fixing by magnetism can have undesirable side effects, such as attraction of other ferromagnetic components, and alignment of the print head using magnetic forces is not as precise as using form-fitting, for example.

Task

The task is now to overcome the aforementioned disadvantages of the prior art and to provide a carrier device that enables a quick and automatic print head change. Furthermore, the task is to present an additive manufacturing system with such a carrier device, with which a method for changing a print head on such a carrier device can also be carried out.

Solution

The above object is achieved by a carrier device for receiving a print head for an additive manufacturing system for producing three-dimensional molded bodies, at least having a carrier plate, which in turn has at least one through-opening. The print head can be arranged at least partially in this opening. This means that at least part of the print head protrudes through the opening. The print head protrudes from above through the opening in the carrier plate downwards.

The opening in the carrier plate is preferably round and runs vertically through the entire carrier device. Furthermore, the opening is preferably arranged centrally on the top side of the carrier plate.

The print head can be arranged at least partially on the carrier device at the same time. This means that the print head or parts of the print head rest on the carrier device, while at the same time another part of the print head protrudes through the opening or is arranged in the opening. Such another part is designed, for example, as a so-called hot end.

Furthermore, at least one clamping unit for locking and/or clamping the print head to the carrier plate is arranged on the carrier plate. This means that the carrier device also has a clamping unit. The clamping unit is arranged concentrically to the opening.

The clamping unit also functions as a locking unit that limits the print head's degrees of freedom. This means that the print head is not arranged so that it can be removed or detached from the carrier device, but is connected or locked to it.

This clamping unit connects the print head to the support device on which the print head sits or rests. The clamping is necessary in order to be able to work with the print head in a precise position. By clamping the print head to the support device, all movements of the support device are transferred directly to the print head. The clamping also ensures repeatability when positioning the print head on the support device. At the same time, tolerances are compensated. Tolerances are defined as dimensional tolerances on the print head and/or support device.

In a further advantageous embodiment, the clamping unit on the carrier device is designed as a rotatable bayonet lock, wherein the bayonet lock has at least two projections extending radially towards the center of the opening. In this case, the bayonet lock is designed in a ring shape, from which the projections extend radially inwards.

At the same time, the bayonet catch is arranged so that it can rotate concentrically to the opening. The bayonet catch is preferably ring-shaped.

In this case, the ring-shaped bayonet catch is mounted in at least two receptacles. The receptacles are arranged on the carrier plate around the opening, so that the ring-shaped bayonet catch is held by the receptacles on the carrier plate, with the receptacles each radially enclosing the ring-shaped bayonet catch. The bayonet catch is thus also arranged so that it can rotate concentrically to the opening.

It is also conceivable that the receptacles have an angular shape, preferably an L-shape, and at least partially surround the ring-shaped bayonet catch. An L-shaped receptacle has two legs that are orthogonal to each other. An L-shaped receptacle can thus be arranged with one leg perpendicular to the carrier plate, with the second leg of the L-shaped receptacle running horizontally, i.e. parallel to the carrier plate, and gripping under the ring-shaped bayonet catch.

It is also conceivable that the ring-shaped bayonet catch is arranged in another way so that it can rotate concentrically to the opening. In general, the ring-shaped bayonet catch is designed as a rotary connection to the carrier plate. For example, the bearing could be designed as a ball bearing ring which is arranged concentrically to the opening. The rotatable inner part of the ball bearing ring is concentrically attached to the bayonet catch and the outer part is arranged on or even in the opening. It is also conceivable that the inner part of the ball bearing ring itself is designed as a ring-shaped bayonet catch with at least two projections extending radially to the center of the opening.

In a further advantageous embodiment, the projections of the bayonet lock on the carrier device each have at least one inclined and/or curved surface for guiding the print head which is at least partially arranged in the opening.

The inclined and/or curved surfaces are not arranged parallel to the carrier plate. Mathematically speaking, the plane of the carrier plate and the plane of the inclined and/or curved surfaces would intersect. The intersection angle between these planes would be greater than 0° and less than 90°. The intersection angle would preferably be between 5° and 30°. The intersection angle is particularly preferably 9-11°. The inclined and/or curved surfaces and the carrier plate itself do not intersect, only the spanned planes.

For example, the projections can be wedge-shaped. In this case, the tapered end of a wedge-shaped projection is aligned in the mathematical sense or against the mathematical sense of the circumference of the opening. In this way, all projections are always aligned in the same circumferential direction of the opening.

The slanted and/or curved surfaces overlap at least part of the print head and force it onto a guide path that is defined by the surfaces of the projections. The projections overlap part of the print head when the ring-shaped bayonet catch has completed at least a partial rotation concentric to the opening in the carrier plate. If the projections overlap, this can be referred to as a closed bayonet catch or a clamping position. If the projections of the bayonet catch do not overlap parts of the print head, this can be referred to as an open bayonet catch or a clamping position. In the clamping position, the print head can be freely removed from the opening in the carrier plate.

In the clamping position, the inclined and/or curved surfaces over at least one part of the print head induce a force on the print head, which pushes the print head in a predetermined direction. This predetermined direction is preferably vertically downwards, along the axis of rotation of the bayonet lock. As the bayonet lock rotates, an increasing force is applied to at least one part of the print head. At the same time, as the force applied increases, a frictional connection can also occur between the projections of the bayonet lock and at least one part of the print head. The force applied by the bayonet lock and any frictional connection firmly clamp the print head in its position in the carrier device. Under these circumstances, a so-called self-locking effect occurs, which prevents the bayonet lock from turning back on its own.

In a further advantageous embodiment, the clamping unit is designed to be clamped and/or unclamped on the carrier device via a Bowden cable and/or the clamping unit has at least one spring for applying force to the clamping unit for clamping and/or unclamping the print head.

The Bowden cable has a Bowden hose and a core, whereby the core is guided through the Bowden hose. Furthermore, the core is designed to be movable in relation to the Bowden hose. The Bowden hose is fixedly arranged on the carrier device. The movable core is arranged on the rotatably mounted, ring-shaped bayonet catch. The core engages tangentially with the bayonet catch. By applying tensile force to the core of the Bowden cable, the bayonet catch is rotated concentrically to the opening. Preferably, at least one spring is arranged between the bayonet catch and the carrier plate in the opposite direction of the force to the Bowden cable. There are at least two types of arrangement.

The spring can be arranged in a tensioned state in the open position of the bayonet catch. The spring then exerts a restoring force on the bayonet catch and moves it into the tensioned position when the spring is released.

As an alternative to the above arrangement, the spring can be in a tensioned state in the clamping position, so that when the spring is relaxed the bayonet lock is opened and thus moved into the unclamping position.

To rotate the bayonet lock, the force is applied to the ring-shaped bayonet lock tangentially to the ring shape. This means that the Bowden cable and/or springs are preferably arranged tangentially to the ring-shaped bayonet lock. Furthermore, the Bowden cable and spring are preferably arranged in the opposite tangential direction of force to the bayonet lock.

In a further advantageous embodiment, the carrier plate of the carrier device has a centering unit for positive centering of the print head on the carrier device. The positive locking follows the lock-key principle.

For this purpose, at least two elevations are arranged on the carrier plate, which form a positive connection to at least part of the print head. The elevations each have recesses on the surface opposite the carrier plate, into which at least part of the print head can be inserted. The recess on the elevations and the at least part of the print head are designed to be congruent with one another. When at least part of the print head engages in the recesses of the elevations on the carrier plate, the print head is forced into a predeterminable position. This positive connection centers the print head.

However, it is also conceivable that the positive locking for centering the print head takes place via recesses on the carrier plate. The recesses are designed to be congruent with elevations on the print head, whereby when the print head is placed on the carrier plate, the elevations engage in the recesses in a form-fitting manner and thus force the print head into a predeterminable position. Centering bores/holes and Centering pins can be provided on congruently formed elevations on the print head.

The centering unit prevents the print head from moving and/or twisting on the carrier plate of the carrier device. Preferably, the recesses on the carrier plate and the elevations on the print head or the elevations on the carrier plate and the recesses on the print head are designed differently. This means that the recesses have a different geometric design to one another. Accordingly, the elevations would also be designed differently to be congruent with the recesses. The different geometric designs prevent the print head from being inadvertently positioned on the carrier plate in the wrong direction.

The above-mentioned object is also achieved by an additive manufacturing system which has at least one carrier device for receiving a print head for producing three-dimensional molded bodies, at least one carrier device guide for moving the carrier device in all three spatial directions, at least one print head which is clamped to the carrier device in the working state of the system, at least one electronic control for controlling the additive manufacturing system, at least one print bed on which at least one three-dimensional molded body is manufactured, and also at least one tool holder which holds at least one print head in a basic position.

The carrier device guide can have a so-called delta design or a Cartesian design. In a Cartesian design, the carrier device is arranged on a linear movement axis, which in turn is arranged on at least one linear movement axis, which in turn is arranged on at least one linear movement axis. All three linear movement axes are orthogonal to one another and form a kinematic chain. Preferably, the three movement axes simultaneously form the three coordination axes x, y and z of a Cartesian coordinate system. The linear movement axes are designed to be movable along their extent. This means that the carrier device arranged on the first linear movement axis can be moved to any location in the volume spanned by the linear movement axes.

The carrier device guide preferably has a delta design. The carrier device has at least three articulation points, at each of which at least one rigid connecting element is arranged so as to extend upwards. The end of the rigid connecting element opposite the articulation point on the carrier device is designed to be movable at least in the vertical direction. This end is, for example, articulated on a vertical rail and is simultaneously designed to be movable along this rail. The articulation points are preferably designed as ball joints. If the rigid connecting elements are moved upwards and/or downwards at their articulation points, which are opposite the articulation points on the carrier device, this movement in turn results in a movement of the carrier device in three-dimensional space, depending on the movements of the rigid connecting elements.

In the additive system, the electronic control takes over the control of electric motors, which generate the movements of the rigid connecting elements and thus also the movements of the carrier device. For this purpose, the system preferably also has an interface to a computer, whereby the control is designed to be connectable to the computer via the interface. According to control data that are present in the control, the carrier device is given precise movements or movement patterns in three-dimensional space via the movements of the rigid connecting elements.

The print bed is preferably designed to be heatable. A heatable print bed allows, for example, various thermoplastics to be processed. The heat of the print bed can create better or defined adhesion conditions for the material to be printed.

The tool holder also has at least one tool holder on which a print head can be arranged. The tool holder has a holding fork onto which a print head can be pushed. The holding fork engages under the print head so that it is held by the holding fork, or the holding fork is inserted into corresponding recesses in the print head or the print head is pushed onto the holding fork so that the print head is thereby held by the tool holder in a basic position.

If the tool holder has several tool holders, these can be designed to be movable. For example, the tool holder with its tool holders can be designed like a revolver.

In a further advantageous embodiment, the tool holder of the additive manufacturing system is vertical and/or horizontal in relation to the Plane which spans the printing bed, is designed to be movable and/or the tool holder has at least one movable tool holder.

This means that the tool holder is designed to be movable in three-dimensional space. This makes it possible to always move to a position that provides the shortest possible travel path from the carrier device to the tool holder for a tool change on the carrier device.

Preferably, the tool holder is always at the same height as the carrier device or slightly offset in height from the carrier device. It is particularly advantageous if the tool holder is arranged somewhat higher than the carrier device, since in order to change a print head, the carrier device must move lower than the lowest point of the print head to be changed on the tool holder and this can lead to a collision with the three-dimensional object to be printed.

The tool holder has a spindle drive, a drive via a toothed belt, a cable drive and/or a linear drive for vertical and/or horizontal movement. The tool holder is arranged on at least one vertical guide rail, along which the tool holder can be moved via a drive just mentioned.

The at least one tool holder is preferably arranged on a belt that runs around the tool holder, so that the tool holder is designed to be movable as the belt moves. The belt is in turn moved by a belt drive that is arranged inside and/or outside the tool holder.

In a further advantageous embodiment, the print head of the additive manufacturing system has a modular holder for holding printing and/or processing units, wherein the modular holder has outwardly protruding projections for clamping by means of the clamping unit of the carrier device and wherein the modular holder has outwardly protruding projections for placing on the carrier device and/or for centering via the at least one centering unit on the carrier device. These projections are also referred to as centering projections.

Various tools can be arranged on the modular holder. For example, a hot end or a laser for processing surfaces can be arranged on the modular holder. Furthermore, measuring probes for measuring object surfaces can be arranged on the modular holder. It is also conceivable to arrange a milling head on the modular holder. This means that the possible uses of the system are not only limited to additive manufacturing processes, but can also be expanded to include metrological and subtractive manufacturing processes. As a result, the term print head should not be seen as restrictive, but rather represents a term for a tool that is held by the modular holder. This means that a print head can also be used for measuring, laser processing, milling, etc. and is not just limited to printing.

A printing unit can be a so-called hot-end, for example. The hot-end is supplied with filament either via a directly connected extruder or via a Bowden tube, at the other end of which there is an extruder that pushes a filament into the Bowden tube. The hot-end is the part of a 3D printer that melts the material to be printed and pushes it out through a connected print nozzle for the printing process.

In addition to printing units, the modular holder can also have processing units, such as milling cutters. The milling cutter would remove material from an object in a defined manner. Another processing unit could also be a laser, which also works subtractively, i.e. by removing material. A measuring probe can also be understood as a processing unit. Such a measuring probe would be able to scan the object three-dimensionally by touching and/or optically the surface of an object and determine the three-dimensional positions of the object surface. Other processing units that could be used include cameras for 3D scanning or grippers. The modular holder thus forms the link between the printing or processing unit and the carrier device. The print head is clamped to the carrier device on the modular holder, which transfers the movements of the carrier device to the printing or processing unit.

The projections protruding outwards on the modular holder for placing on the carrier device and/or for centering via the at least one centering unit on the carrier device are preferably arranged in the upper region of the modular holder. The upper region of the modular holder is characterized in that this region is located on the side of the carrier device facing away from the print bed. Accordingly, the lower region of the modular holder is located diametrically opposite the upper region. ral opposite on the side of the support device facing the print bed.

In the event that the projections in the upper area of the modular holder engage in a form-fitting manner in the centering unit for centering, their shape is congruent with the recesses in the centering unit. They preferably engage in the recesses from above. The projections and the corresponding recesses in the centering unit advantageously have different geometric designs. This prevents positioning in the wrong direction.

The tools held by the modular holder are arranged in the lower area and/or upper area of the modular holder, depending on the tool to be held. Outwardly protruding projections for clamping by means of the clamping unit of the carrier device are also arranged in the lower area. These projections are preferably designed as pins and point radially outwards along their longitudinal or rotational axis. A pin has the shape of a solid cylinder. However, it is also conceivable that the projections are designed as wedges running radially outwards.

The above-mentioned object is also achieved by a method for changing a print head on a carrier device in an additive manufacturing system, which method has at least the steps of clamping and/or unclamping the print head. At least the steps of providing the print head in the tool holder, transferring the print head to the carrier device and at least partially passing the print head through the opening of the carrier device, aligning the print head in the opening of the carrier device by the centering unit by means of positive locking, and clamping the print head in the opening of the carrier device using the clamping unit, wherein the projections of the clamping unit at least partially overlap the print head in the working state, are carried out.

When the print head is provided in the tool holder, the at least one print head arranged on the tool holder is moved to a removal position. In this position, the print head is accessible to the carrier device by allowing the carrier device to move towards the print head from below. Alternatively, the carrier device moves towards the tool holder and the tool holder lowers from above towards the carrier device.

This means that the print head is at least partially guided through the opening of the carrier device. As already mentioned above, the carrier device can move towards the print head from below or the tool holder with the print head can be lowered from above towards the carrier device.

Shortly before the print head is placed on the carrier device, it is aligned by the centering unit in that the outwardly protruding projections of the print head engage in a form-fitting manner in recesses in the centering unit that are congruent with the projections, thus forcing the print head into a predetermined position. At the same time, the print head is seated on the carrier device.

Next, the print head is clamped in place by the clamping unit. The print head is clamped firmly to the carrier device. If the print head is clamped firmly to the carrier device, the print head can also be said to be in the working state. This state is characterized by the carrier device and the print head forming a rigid connection, so that all movements of the carrier device are transferred exactly to the print head without the print head moving relative to the carrier device.

When clamping, the bayonet catch of the clamping unit is rotated about its axis of rotation so that it is in a clamping position. The projections of the bayonet catch overlap at least part of the print head. As a result of the slanted and/or curved surfaces of the projections and the rotational movement of the bayonet catch, a force is exerted on the print head perpendicular to the axis of rotation of the bayonet catch, as the print head is pushed downwards by the slanted and/or curved surfaces of the projections of the bayonet catch. This presses the print head, which is immovably arranged in its position by the centering unit, onto the carrier device.

The rotational movement of the bayonet lock is carried out by a Bowden cable and/or a spring, whereby the Bowden cable and/or spring act tangentially on the bayonet lock, so that a linear movement of the Bowden cable or the spring becomes a rotational movement.

In a further advantageous embodiment of the method, the clamping unit is moved into an unclamping position and the carrier device for unclamping the print head moves with the print head unclamped by the clamping unit in the opening of the carrier device to the work tool holder. In the next step, the print head is moved into a home position on the tool holder.

For example, the print head is pushed or placed onto the tool holder by moving the carrier device. As soon as the print head is in the home position on the tool holder, the tool holder can either move upwards with the print head away from the carrier device or the carrier device can lower itself downwards with respect to the tool holder. In both procedures, the print head is preferably completely guided out of the opening of the carrier device so that another print head can be inserted and clamped into the opening of the carrier device.

Further advantages, features and design options emerge from the following description of figures of non-limiting embodiments.

Short description of the drawings

• 1 eine Trägervorrichtung mit Druckkopf von schräg oben,
• 2 eine Trägervorrichtung mit eingespanntem Druckkopf von schräg unten,
• 3 eine Verspanneinheit mit Bowdenzug und Federn in der Ansicht von unten,
• 4 einen Ausschnitt des oberen Teils des Druckkopfs mit Verspanneinheit von schräg oben,
• 5 eine perspektivische Ansicht einer additiven Fertigungsanlage,
• 6 eine Detailansicht der additiven Fertigungsanlage von schräg oben,
• 7 einen Werkzeughalter mit zwei Druckköpfen jeweils in der Grundposition von schräg oben,
• 8 einen modularen Halter ohne Werkzeug von schräg unten,
• 9 einen Druckkopf von schräg oben,
• 10 eine Zugvorrichtung für einen Bowdenzug und
• 11 ein Anlagenschema einer additiven Fertigungsanlage.

In the drawings shows:

• 1 a carrier device with print head from above,
• 2 a support device with a clamped print head from below,
• 3 a tensioning unit with Bowden cable and springs in the view from below,
• 4 a section of the upper part of the print head with clamping unit from above,
• 5 a perspective view of an additive manufacturing facility,
• 6 a detailed view of the additive manufacturing plant from above,
• 7 a tool holder with two print heads each in the basic position from above,
• 8th a modular holder without tools from below,
• 9 a print head from above,
• 10 a pulling device for a Bowden cable and
• 11 a plant diagram of an additive manufacturing plant.

In the drawings, elements provided with the same reference symbols correspond essentially to one another, unless otherwise stated. Furthermore, we refrain from showing and describing components that are not essential to understanding the technical teaching disclosed herein. In the following, the reference symbols are not repeated for all elements already introduced and shown, provided that the elements themselves and their function have already been described or are known to a person skilled in the art.

Detailed description of implementation examples

1 shows a carrier device 1 with a print head 3 in a view obliquely from above. The carrier device 1 is part of an additive manufacturing system for producing three-dimensional molded bodies. The central component of the carrier device 1 here is a carrier plate 2, which can be seen in the middle. The carrier plate 2 essentially has the shape of an isosceles triangle, the triangle tips of which are cut off. On the outer sides of the triangular carrier plate 2, a ball head 26 extending obliquely upwards is arranged at the outer ends of the respective triangle side or the respective outer side of the triangular carrier plate 2. This ball head 26 forms part of a ball joint, which is not shown here. A print head 3 is arranged in the middle of the carrier plate 2. A part of the print head 3 protrudes downwards through an opening on the carrier plate 2. The opening, which is arranged in the middle of the carrier plate 2, is covered by the print head 3. As a result, the opening is here in 1 and not visible in the following figures.

The print head 3 has a substantially cylindrical shape, the axis of rotation of which is aligned vertically, i.e. at the same time orthogonally to the carrier plate 2 of the carrier device 1. The cylindrical shape of the print head 3 is stepped several times towards the top, with the outer diameter of the cylindrical shape decreasing with each step. Print head feeds 8 are arranged at the upper end of the cylindrical shape of the print head 3. These print head feeds 8 have, for example, at least one Bowden tube 6 in which a filament is guided, and at least one cable for supplying electrical energy and/or for transmitting sensor data.

A hot-end 15 is arranged opposite the print head feeds 8 with respect to the vertical extension of the print head 3, which extends vertically downwards and is partially covered by the carrier plate 2, so that only the lower end of the hot-end 15 is visible.

The print head 3 further comprises at least two centering devices on its lateral surface projections 31, which in the embodiment shown are diametrically opposed and extend radially outward in their longitudinal extension away from the print head 3. More than two centering projections 31 can also be provided on the print head 3. The number of centering projections 31 on the print head 3 is not limited to just two centering projections 31. In the embodiment shown, the centering projections 31 have different widths. The width of a centering projection 31 is defined as an extension orthogonal to the longitudinal extension.

The centering projections 31 each rest on the centering units 4, which are designed as elevations and extend upwards from the carrier plate 2. At the top, the centering devices 4 have recesses that are designed to be congruent with the engaging centering projections 31 of the print head 3. The centering projections 31 engage in these recesses and are thereby forced into a certain position predetermined by the centering devices 4 in a form-fitting manner. Due to the different geometric configurations of the centering projections 31, only one positioning of the print head 3 is possible, so that the risk of incorrect positioning is excluded. In general, the centering projections 31 are to be understood as part of the print head 3.

Furthermore, a Bowden cable 5 is shown, which comes from the right in the figure and is arranged to run under the carrier plate 2. The Bowden cable 5 is used to transmit power for a tensioning unit, which is also arranged below the carrier device 1 and is covered by the carrier plate 2, which is why it cannot be seen in the embodiment shown. The structure of the Bowden cable 5 is also shown schematically, with a Bowden hose 6 running to the right, which is cut off on the right in the image. This section of the Bowden hose 6 only serves to illustrate the structure of the Bowden cable 5 and is not present in the technical implementation. A core 7 runs inside the Bowden cable 5 and is covered by the floor hose 6. The core 7 is preferably designed as a wire rope.

The 2 shows a carrier device 1 with a clamped print head 3 from below. It shows the carrier device 1 from the 1 from below at an angle, so that the underside of the carrier device 1 can be seen instead of the top. A modular holder 11 is arranged directly in the middle below the carrier plate 2. The modular holder 11 is part of the print head 3. The modular holder 11 has a cylindrical shape, the axis of rotation of which is aligned vertically downwards.

A hot end 15 is arranged in the middle of the modular holder 11, which is essentially cylindrical and extends downwards. A print nozzle 14 is arranged at the lower end of the hot end 15. During 3D printing, the material to be printed leaves the print head 3 through the print nozzle 14.

Pins 12 which have a cylindrical shape are arranged on the modular holder 11. The pins 12 each have a longitudinal extension which runs radially outwards from the outer surface of the modular holder 11. The pins 12 are generally to be understood as part of the print head 3.

A ring-shaped bayonet catch 9 is arranged concentrically around the modular holder 11. The bayonet catch 9 represents a clamping unit which clamps the print head 3 to the carrier plate 2 of the carrier device 1 via the pins 12. The ring-shaped bayonet catch 9 is mounted via receptacles 16 and is simultaneously arranged on the underside of the carrier plate 2 concentrically to the modular holder 11. The receptacles 16 are arranged in a circular arrangement concentrically to the modular holder 11. The receptacles 16 allow the ring-shaped bayonet catch 9 to be rotatably mounted on the underside of the carrier plate 2.

Projections 13 extend radially inwards from the ring-shaped bayonet catch 9 and overlap the pins 12. This means that the projections 13 are located between the carrier plate 2 and the pins 12. At the same time, the projections 13 each have an inclined and/or curved surface on the surface facing the respective pin 12. If the ring-shaped bayonet catch 9 is rotated, the projections 13 overlap the pins 12 and push them vertically downwards along the inclined and/or curved surface. The pins 12 rub along the projections 13. This can lead to a frictional connection, so that the surface friction between the pins 12 and the projections 13 causes a self-locking effect that prevents the ring-shaped bayonet catch 9 from rotating back into an open position - also known as the unclamping position. In the 2 the ring-shaped bayonet lock 9 can be seen in a closed position. This can also be referred to as a clamping position.

The ring-shaped bayonet catch 9 is rotated via a Bowden cable 5, whereby the Bowden hose 6 of the Bowden cable 5 is fixedly arranged on a holder 16 and the core 7 of the Bowden cable 5 is arranged tangentially on the ring-shaped bayonet catch 9. With tensile force Impact on the core 7 pulls the ring-shaped bayonet catch 9, causing it to rotate.

Two springs 10 are arranged on the ring-shaped bayonet catch 9, one end of which engages tangentially with the ring-shaped bayonet catch 9 and the other end of which is fixedly arranged on the holder 16. The force of the springs 10 acts tangentially to the ring-shaped bayonet catch 9 opposite to the core 7 of the Bowden cable 5. This generates a restoring force for the ring-shaped bayonet catch 9. When a tensile force is applied to the core 7, the springs 10 are tensioned. When the tensile force is removed from the core 7, the tensioned springs 10 pull the ring-shaped bayonet catch 9 back to the position it was in before the tensile force was applied by the core 7. The springs 10 preferably still have a pre-tension in the “relaxed” position.

The 3 shows a clamping unit with Bowden cable 5 and springs 10 in a view from below. The clamping unit is designed here as a ring-shaped bayonet catch 9. Three receptacles 16 are arranged concentrically around the ring-shaped bayonet catch 9 and radially surround the ring-shaped bayonet catch 9. The receptacles 9 serve here for the rotatable mounting of the ring-shaped bayonet catch 9.

Furthermore, a Bowden cable 5 is arranged on the ring-shaped bayonet catch 9, whereby the Bowden cable 5 consists of a core 7 and a Bowden hose 6 surrounding the core 7. The Bowden hose 6 is fixedly arranged at one end on a receptacle 16. The core 7 at this end is guided through the receptacle 16 and arranged on the ring-shaped bayonet catch 9. When a tensile force is applied to the core 7, it pulls the ring-shaped bayonet catch 9 towards the receptacle 16 in which the Bowden hose 6 is fixedly arranged. This generates a rotary movement of the ring-shaped bayonet catch 9.

Furthermore, two springs 10 are arranged on the ring-shaped bayonet catch 9. One end of each spring 10 is fixedly arranged on a holder 16. The opposite end of each spring 10 is arranged on the ring-shaped bayonet catch 9. The direction of force of the springs 10 is arranged tangentially to the ring-shaped bayonet catch 9, opposite to the core 7.

Three projections 13 extend radially inwards from the ring-shaped bayonet catch 9 and are arranged at equal distances from one another. The projections 13 each have a rectangular shape in their basic form, the longitudinal extension of which runs tangentially to the circumference of the ring-shaped bayonet catch 9. The projections 13 each have an inclined and/or curved surface, with the inclination or curvature running towards the viewer, so that they 3 cannot be seen.

The 4 shows a section of the upper part of the print head 3 with clamping unit from above. This figure essentially shows the object from 1 without carrier device 1. The print head 3 has a modular holder 11 in the upper part with a substantially cylindrical shape, from which two centering projections 31 extend outwards in the radial direction on the outer surface. The centering projections 31 are diametrically opposite each other. Below the modular holder 11, a ring-shaped bayonet lock 9 with receptacles 16 and Bowden cable 5 is concentrically connected. The Bowden cable 5 here also has a Bowden hose 6 and a core 7, with the Bowden hose 6 enclosing the core 7. Furthermore, springs 10 are arranged on the ring-shaped bayonet lock 9, as already shown in 3 was described.

The modular holder 11 has two recesses 17 above the centering devices 31, which are designed as round holes running parallel to one another. Furthermore, a hot end 15 is arranged below the modular holder 11, which extends vertically downwards and is partially covered by the ring-shaped bayonet lock 9 in this view.

The 5 shows a perspective view of an additive manufacturing system. The basic structure of this system is formed by a frame 24, which encloses all components of the system. Within the frame 24, a print bed 18 is arranged at the bottom, on which three-dimensional molded bodies can be manufactured. A carrier device 1 with a print head 3 is arranged above the print bed 18, the print head 3 being in a working position in the arrangement shown. The carrier device 1 is articulated to rigid connecting elements 30 in the form of rods. The articulation to the carrier device 1 takes place via the ball heads 26, which are in 1 The rigid connecting elements 30 extend obliquely upwards away from the carrier device 1. The ends of the rigid connecting elements 30 opposite the carrier device 1 are each arranged on the vertical sides of the frame 24 so that they can be moved in the vertical direction. This means that the rigid connecting elements 30 are, for example, hinged to vertically movable slides which can be raised and lowered individually. are designed to be movable. The support device 1 together with the rigid connecting elements 30 form a so-called delta design.

Furthermore, next to the arrangement of the carrier device 1 and rigid connecting elements 30, a tool holder 20 is arranged, which has two print heads 3 at the level of the carrier device 1. The print heads 3 held by the tool holder 20 are in a basic position.

Print head feeders 8 extend upwards from the print heads 3, which are shown here only schematically and are therefore cut off in the air.

In 6 is a detailed view of the additive manufacturing system from above. It essentially shows all the components that are also used in 5 are shown. Support device 1 and rigid connecting elements 30 form a delta design. A print head 3 is also arranged on the support device 1. In this arrangement, the print head 3 is in a working position. A print bed 18 is arranged below the support device 1 in the middle of the delta design.

A tool holder 20 is arranged to the side of the print bed 18, on which two print heads 3 are arranged. These print heads 3 are in a basic position in the arrangement shown. The tool holder has a spindle 19 in the middle, which runs vertically through the tool holder 20. The spindle 19 extends vertically upwards from the floor of the production system. The tool holder 20 also has a guide rail 23, which guides the tool holder 20 in a vertical direction. It is arranged to the side of the spindle 19. By rotating the spindle 19 about its own axis, the tool holder 20 can be moved up and down along the guide rail 23. The tool holder 20 and spindle 19 form a so-called spindle drive. The spindle 19 can be driven, for example, by an electric motor (not shown here).

The tool holder 20 also has a torsion shaft 32. It is arranged to the side of the spindle 19 and the guide rail 23. Like the spindle 19 and the guide rail 23, it runs vertically upwards from the floor of the production facility through the tool holder 20. The torsion shaft 32 has a square profile. At the point where the torsion shaft 32 passes through the tool holder 20, a driver is arranged, which has a recess designed to match the square profile. If the torsion shaft 32 is rotated along its axis of rotation, for example by an electric motor - not shown here - the driver rotates with it. The driver, which is arranged in the tool holder 20, can, for example, move various tool holders 21 arranged on the belt via a belt. In this case, the driver is the drive for the belt. In the embodiment shown, such a belt, which is hidden here, would run along the circumference of the tool holder 20.

Print head feeders 8 extend upwards from the print heads 3, which are shown here only schematically and are therefore cut off in the air.

In this view, a possible print head change can be easily understood. The carrier device 1 would move with the print head 3 arranged there to the tool changer 20 and bring the print head 3 into a home position on the tool changer 20.

The 7 shows a tool holder with two print heads, each in the basic position, viewed diagonally from above. The tool holder 20 has an elongated oval shape, with the ends of the longitudinal extension being semicircular. In this illustration, the tool holder 20 is made of 6 in detail. The spindle 19 runs vertically through the middle of the tool holder 20. The tool holder 20 and spindle 19 together form a spindle drive so that the tool holder 20 can be moved up and down by rotating the spindle 19 about its axis. The tool holder 20 is guided by a guide rail 23 in a vertical direction so that the tool holder 20 is simultaneously prevented from rotating about the axis of the spindle 19. Furthermore, a torsion shaft 32 is arranged opposite the guide rail 23.

Tool holders 21 are arranged on the side of the tool holder 20. These tool holders 21 extend radially outwards with respect to the tool holder 20. The tool holders 21 are also arranged so that they can be moved around the tool holder 20. The tool holders 21 are preferably arranged on a belt which is moved by a driver in the tool holder 20. The belt is preferably arranged in the tool holder 20 and is therefore hidden in this illustration. The driver is moved by rotating the torsion shaft 32.

A tool holder 21 forms a holding fork 25 at the outward-facing end. A print head 3 can be pushed onto this holding fork 25. In this case, a print head 3 with its recesses 17, which are 4 to see are pushed onto the prongs of the holding fork 25. A slight inclination of the holding fork 25 towards the tool holder 20 causes a pushed-on print head 3 to slide towards the tool holder 20 and thus remain in its home position. Furthermore, the prongs of the holding forks 25 are preferably designed to taper slightly towards each other in the direction of the tool holder 20. This allows the print heads 3 to experience a slight clamping effect when pushed on, which holds them in their home position through slight friction between the holding fork 25 and corresponding recesses on the print head 3.

The 8th shows a modular holder 11 without tools from below. The modular holder 11 has a substantially cylindrical shape with several steps.

Concentric to the rotation axis of the cylindrical shape of the modular holder 11, the latter has a continuous opening. The lower end of this opening is designed as a holder for a tool 27. In the embodiment shown, a hot end, for example, can be arranged in this holder for a tool 27.

On the lowest cylindrical step of the modular holder 11, three pins 12 extend radially outwards. On the uppermost cylindrical step, two recesses 17 are arranged in the form of two holes running parallel to each other. In these recesses 17, corresponding holding forks 25 are inserted, as they are used, for example, in 7 shown. Between recesses 17 and pins 12, two centering projections 31 also extend radially outward, which are also diametrically opposed. In 8th only one centering projection 31 is visible, since the opposite centering projection 31 is covered by the modular holder 11.

The 9 shows a print head from above. This illustration essentially shows a print head 3, as it is already shown in 4 can be seen in detail, but without the ring-shaped bayonet lock 9. The upper part of the print head 3 is formed by a modular holder 11. The modular holder 11 has recesses 17, centering projections 31 and pins 12, as already shown in the 8th are shown. The modular holder 11 is connected to a hot-end 15 which extends vertically downwards and is also arranged at the bottom of the modular holder 11. Print head feeds 8 lead upwards from the upper end of the modular holder 11. They supply the print head 3 with filament, electrical energy and transmit data.

The 10 shows a pulling device for a Bowden cable 5. The pulling device is designed as a housing in which an eccentric 28 is accommodated. A Bowden cable 5 is arranged on a housing wall, which is also guided through the housing wall into the interior of the housing. The core 7 of the Bowden cable 5 is connected to the eccentric 28. The Bowden hose 6 of the Bowden cable 5 is fixedly arranged on the housing wall.

The eccentric 28 is designed as a disk that has a pivot point offset from its center. The core 7 is arranged at this pivot point. If the eccentric 28 rotates, the core 7 is pulled out of the Bowden hose 6, whereby a tensile force can be transmitted with the core 7 via the Bowden cable 5. The core 7 can be attached to a driver, whereby the driver is moved via the pivot point on the eccentric 28. Due to its geometric design and arrangement in the housing, the driver is arranged so that it can be moved linearly in the pulling direction of the core 7. The driver is preferably cuboid-shaped and is guided in the housing, which is also preferably cuboid-shaped, along the longitudinal extension of the housing.

Preferably, the eccentric 28 is driven by an electric motor. The supply lines required for control signals and/or electrical energy are fed into the housing via a traction device feed 29.

The tensile force transmission is preferably used for the rotary movement of the ring-shaped bayonet lock 9, not shown here.

The 11 shows a system diagram of an additive manufacturing system. This diagram shows possible components of an additive manufacturing system in the form of a 3D printer and how they interact. The heated construction platform corresponds to a print bed 18, the tool holder to a modular holder 11 and the effector to a carrier device 1. The material to be printed is fed to the print heads 3, here understood as a combination of tool holder and hot end, via extruders. As can be seen in the system diagram, the tool holder holds a print head, shown here as a combination of tool holder and hot end, in a basic position. On the effector there is a print head, shown here as a combination of tool holder and hot end, which is located above the print bed, here marked as a heated construction platform, in a working position.

Although the invention has been illustrated and described in detail by the advantageous embodiments, the invention is not limited by the disclosed examples. Other variations can be derived from this by the person skilled in the art without departing from the scope of the invention. In particular, the invention is not limited to the combinations of features specified below, but other combinations and partial combinations that are obvious to the person skilled in the art can also be formed from the disclosed features.

List of reference symbols

1

Carrier device

2

Carrier plate

3

Printhead

4

Centering unit

5

Bowden cable

6

Bowden hose

7

Soul

8th

Printhead feeders

9

Bayonet lock

10

Feather

11

holder

12

Pin code

13

head Start

14

Pressure nozzle

15

Hot end

16

Recording

17

Recess

18

Print bed

19

spindle

20

Tool holder

21

Tool holder

23

Guide rail

24

Frame

25

Holding fork

26

Ball head

27

Recording

28

eccentric

29

Traction device feed

30

Connecting element

31

Centering projection

32

Torsion shaft

Claims (9)

Carrier device for receiving a print head for an additive manufacturing system for producing three-dimensional molded bodies, wherein the carrier device (1) has at least one carrier plate (2) which has at least one through opening in which the print head (3) can be at least partially arranged, wherein the print head (3) can be at least partially arranged on the carrier device (1), and wherein the carrier plate (2) further has at least one clamping unit for locking and/or clamping the print head (3) to the carrier plate (2), which is arranged concentrically to the opening and is designed as a rotatable bayonet catch (9), and the bayonet catch (9) has at least two projections extending radially to the center of the opening. Support device according to Patent claim 1 , characterized in that the projections of the bayonet closure (9) each have at least one inclined and/or curved surface for guiding the print head (3) arranged at least partially in the opening. Support device according to Patent claim 1 or 2 , characterized in that the clamping unit is designed to be clamped and/or unclamped via a Bowden cable (5) and/or the clamping unit has at least one spring (10) for applying force to the clamping unit for clamping and/or unclamping the print head (3). Support device according to Patent claim 1 , characterized in that the carrier plate (2) has at least one centering unit (4) for positively centering the print head (3) on the carrier device (1). Additive manufacturing plant comprising - at least one carrier device (1) according to at least one of the Patent claims 1 - 4 for producing three-dimensional molded bodies, - at least one carrier device guide for moving the carrier device (1) in all three spatial directions, wherein the carrier device guide has a delta design or a Cartesian design, - at least one print head (3) which is clamped to the carrier device (1) in the working state of the system, - at least one electronic control for controlling the additive manufacturing system - at least one print bed (18) on which at least one three-dimensional molded body is manufactured and furthermore - at least one tool holder (20) which holds at least one print head (3) in a basic position. Additive manufacturing plant according to Patent claim 5 , characterized in that the tool holder (20) is designed to be movable vertically and/or horizontally in relation to the plane which spans the printing bed (18) and/or the tool holder (20) has at least one movable tool holder (21). Additive manufacturing plant according to Patent claim 5 , characterized in that the print head (3) has a modular holder (11) for holding printing and/or processing units, wherein the modular holder (11) has outwardly projecting projections for clamping by means of the clamping unit of the carrier device (1), and that the modular holder (11) has outwardly projecting projections for placing on the carrier device (1) and/or centering via the at least one centering unit (4) on the carrier device (1). Method for changing a print head on a carrier device according to at least one of the Patent claims 1 - 4 in an additive manufacturing plant according to at least one of the Patent claims 5 - 7 comprising at least the steps for clamping and/or unclamping the print head: a) providing the print head (3) in the tool holder (20), b) transferring the print head (3) to the carrier device (1) and at least partially passing the print head (3) through the opening of the carrier device (1), c) aligning the print head (3) in the opening of the carrier device (1) by the centering unit (4) by means of positive locking and d) clamping the print head (3) in the opening of the carrier device (1) by means of the clamping unit, wherein the projections of the clamping unit at least partially overlap the print head (3) in the working state. Procedure according to Patent claim 8 , characterized in that the clamping unit is brought into an unclamping position and the carrier device (1) for unclamping the print head (3) with the print head (3) unclamped by the clamping unit in the opening of the carrier device (1) moves towards the tool holder (20) and by a movement the print head (3) is brought into a basic position on the tool holder (20).

Images