Patent ID: 12257777

It should be noted that items which have the same reference numbers in different Figures, have the same structural features and the same functions, or are the same signals. Where the function and/or structure of such an item has been explained, there is no necessity for repeated explanation thereof in the detailed description.

DESCRIPTION OF EMBODIMENTS

FIG.1schematically shows a fused filament fabrication device1according to an embodiment of the invention. The fused filament fabrication system1comprises a build plate2which is moveably arranged in a housing3of the system1. The system1comprises a number of print heads31, only one of which is shown inFIG.1. Each print head31comprises an extrusion channel (not visible inFIG.1) and a nozzle51at the end of the extrusion channel. Furthermore, the print head31comprises a heating element52arranged to heat part of the extrusion channel, sometimes referred to as melt chamber. A print head mount4is arranged for releasable connection with any of the print heads31.

A gantry5is arranged to move the print head mount4relative to the build surface2′ of the build plate2in an X, Y and Z direction. The gantry5is a guide rail system that is desirably configured to move the print heads31in a horizontal X-Y plane within build chamber based on signals provided from a control system25. The horizontal X-Y plane is a plane defined by an X-axis and a Y-axis, where the X-axis, the Y-axis, and the Z-axis are orthogonal to each other. In an alternative embodiment, build plate2may be configured to move along two axes within the housing3(e.g., X-Z plane or the Y-Z plane), and the loaded print head31may be configured to move along a single horizontal axis (e.g., the X-axis or the Y-axis). Other similar arrangements may also be used such that one or both of the build plate2and the loaded print head31are moveable relative to each other. Also, the build plate2may be replaced by a conveyer belt which comprises the build surface2′.

The system1further comprises a number of filament modules61only one of which is shown inFIG.1. Each of the filament modules61comprises a filament channel61C for passing through of a filament11. The filament modules61are arranged to be releasably connected to a respective one of the print heads31, wherein in a connected configuration, the filament channel61C is aligned with the extrusion channel of the print head31, as will be explained in more detail below.

The system1further comprises a number of filament docks71,72,72each of which arranged for docking one of the filament modules61. Furthermore, a print head dock8is arranged in the system for docking any of the print heads31. Each of the filament docks71,72,73comprises two pins90which can interact with two recesses in the filament module61. In this way, a filament module, such as the filament module61, can be releasably connected to a filament dock, such as filament dock71, or one of the others. It is noted that other types of male/female couplings are conceivable.

In this embodiment, at a back side of the system1, a number of filament feeders9is arranged, each of the filament feeders being connected via a Bowden tube61B to a respective one of the filament modules61and configured for feeding the filament11to the respective one of the filament modules61. For reasons of simplicity only one of the feeders and Bowden tubes is shown inFIG.1. The filament11is retrieved from a filament storage21. Each filament feeder9may comprise a housing, a channel, one or more idle wheels, one or more feeder wheels and an actuator for driving the feeder wheels. Alternatively, some or all of the filament feeders9may be part of a feeder system (not shown) which comprises multiple parallel channels but only one common actuator that is arranged to feed one of the filaments at a time by way of using a selector. The selector may comprise an arrangement that selectively presses filament onto the feeder wheel(s) by way of moving and removing idle wheels onto the filament. Such a feeder system will have a number of filament inputs and the same number of outputs which will then be connected by Bowden tubes to the respective filament modules61.

Each of the filament modules61is provided with a respective print head power supply cable61P, and comprises a releasable electrical connection (see e.g. number412inFIG.4A) to provide power to the connected print head31. The power supply cable61P may be connected to a power source that can be arranged in the control system25or separate from the control system25.

It is noted that fromFIG.1it seems that the filament module61is floating in air, whereas in practice the filament module61is attached to the print head31and/or docked into one of the filament docks71,72,73.

In this embodiment, the system1comprises a control system25arranged to control the gantry5so as to select one print head from the number of print heads, to obtain a selected print head31. The control system25may be arranged internal or external of the system housing3. Part or all of the control system25may also be located remote from the housing3.

FIG.1shows an opening27for giving access to the build plate2. It is noted that in this example the housing3is open at the top, but a further closure can be arranged on top to seal off the build chamber completely. In this example the system1also comprises a bar28to support the filament docks71,72,73and the print head dock8. The bar28may be fixed in the housing3, but alternatively it may be movably arranged within the housing3. In an embodiment, the bar28can be moved in the X-direction and/or the Z-direction.

FIG.2is a schematic top view of the embodiment ofFIG.1. InFIG.2, three filament module61,62,63are present, each of them docked in a corresponding filament dock71,72,73. Also three print heads31,32,33are shown. Each of the print heads31,32,33can be docked in the print head dock8, and alternatively, via one of the filament modules61,62,63, in any of the filament docks71,72,73. Docking of the print heads in these filament docks is possible since a print head can be attached to a filament module, which again can be attached to a filament dock.

FIG.2in fact shows a switching state wherein the first print head31is mounted onto the print head mount4without having a filament module attached. As can be seen fromFIG.2, the print head32and the print head33are docked in the filament docks72,73, respectively.

If the current print head31needs to be used in combination with a filament present in the filament module61, then the control system25will operate the gantry5in such a way that the print head31attached to the print head mount4is moved to the filament dock71, see arrow201.

If another print head, such as print head32, needs to be used, then the control system25will operate the gantry5in such a way that the print head31attached to the print head mount4is moved to the print head dock8, see arrow202.

FIG.3schematically shows the print head31after having picked up the filament module61from filament dock71. The arrow201indicates the docking action as was shown inFIG.2, and the arrow203indicates the undocking action. Before the undocking action, the filament module61is locked onto the print head31. Due to this locking the filament module61stays attached to the print head31during the retraction by the gantry. In an embodiment this locking is achieved by feeding the filament though the filament module61and, at least partly, into the extrusion channel of the print head31as will be explained in detail below. InFIG.3, reference102indicates the build chamber.

FIG.4Aschematically shows a perspective view of the filament module61according to an embodiment. In this embodiment, the filament module61comprises a wedge-shaped body having a through hole which is referred to as the filament channel61C. Two recesses401,402are arranged in the wedge-shaped body to receive the pins90of the filament dock71. The filament module61may also comprise a magnetic coupling410arranged to connect the filament module61to the filament dock71. For that purpose, the filament dock71may comprise a ferromagnetic side wall or a suitably placed magnetic coupling part cooperating with the magnetic coupling410. The magnetic coupling should be strong enough to retain the filament module61when an attached print head31is retracted from the filament dock61in the unlocked state. On the other hand, the magnetic coupling should be weak enough to let go of the filament module61when an attached print head31is retracted from the filament dock61in the locked state.

The filament module61may also comprise a releasable electric coupling412arranged to relay power to the attached print head31(see also number512inFIG.4B). Power is supplied via the power cable61P into the filament module61and through the electrical coupling412to the print head31. The same may account for control signals coming from the control system25and going to the print head31or vice versa.

FIG.4Bschematically shows a perspective view of the print head31according to an embodiment. In this embodiment, the print head31comprises a box shaped main body having a wedge shaped recess501at the top which extends from a docks facing side (i.e. the front side inFIG.4B) until a ridge82that is arranged at the top side of the print head31. The print head31comprises an extrusion channel with an entrance502as indicated inFIG.4B. The print head31comprises a nozzle which is not shown inFIG.4B. In the event that the print head31is moved towards the filament dock71having the filament module61ofFIG.4Bdocked therein, the filament module61is sliding in the recess501of the print head31. If the print head mount4is disconnected from the print head31and moved away from the print head31, the print head31will not fall down. This is due to the fact that a vertical movement is prevented because the wedge shaped filament module body is wider at the bottom as compared to its top part.

FIG.5Aschematically shows a cross section of an assembly of a print head31and a filament module61according to a further embodiment. In this embodiment, the filament module61has a rectangular cross section which co-operates with a rectangular shaped recess in the top of the print head31.FIG.5Bschematically show a cross section of an assembly of a print head31and a filament module61according to a further embodiment. In this embodiment, the filament module61has a C-shaped cross section which provides for sufficient support of the print head in case the print head31is parked in the filament dock71without being supported by the print head mount4.

FIG.6schematically shows a side view of the print head31, also referred to as the selected print head31, placed in a so-called parking state. In this parking state the selected print head31is docked in one of the filament docks71via the filament module61that is currently attached to the print head31. The print head31comprises an extrusion channel31E and in this embodiment also a feeder31F. Since the feeder31F is arranged directly within the print head31, this feeder is referred to as the direct feeder31F whereas the feeder9feeding the filament to the print head (seeFIG.1) via the Bowden tube61B (see alsoFIG.3) is then referred to as the prefeeder9. As can be seen fromFIG.6, the filament11if fed into the filament module61but not into the print head31.

FIG.7schematically shows the print head31and the filament module61being in the same parking state as inFIG.6but now the filament11is fed into the print head31, i.e. through the extrusion channel31E of the print head31. In order to be able to print, the filament11is fed all the through to the nozzle51from where it is deposited onto the build plate2.

Starting from the parking state shown inFIG.6, the print head31can be moved away from the filament dock71in the X-direction, seeFIG.8. Since the filament11is not (yet) fed into the extrusion channel31E, it will not prevent the movement of the print head31relative to the filament module61.FIG.8schematically shows that the print head31is separated from the currently attached filament module61. The filament module61will stay docked in the filament dock71. To avoid that the filament module61erroneously follows the print head31in the X-direction due to friction, a coupling force between the filament module61and the filament dock71can be increased by using e.g. magnetic couplings410as shown inFIG.4A.

Starting from the parking state shown inFIG.7, the print head31can be moved away from the filament dock71in the X-direction, seeFIG.9. Since the filament11is now fed into the extrusion channel31E, it will prevent the movement of the print head31relative to the filament module61.FIG.9schematically shows that the print head31is separated from the filament dock taking along the currently attached filament module61. The filament11locks the filament module61to the print head31at least in the X-direction.

It is noted that different types of filament can be used for the above described method. The filament11can have different diameters, such as 2.85 mm or 1.75 mm, and may be manufactured from different materials such as ABS, PLA, PVA, PC or any other type of material suitable for FFF. Such materials and diameters all provide for sufficient strength to be able to lock the filament module61to the print head and overcome possible counter forces originating from the magnetic couplings410or from friction between the recesses401,402in the filament module61and the pins90of the filament dock71, see alsoFIG.3.

Additionally, or alternatively, the locking of the filament module61to the print head31may be achieved using a locking mechanism arranged in the filament module61and/or the print head31.FIG.9shows an example of a locking mechanism78. It is noted that this locking mechanism78is not shown inFIGS.6-8. The locking mechanism78may comprise a ferromagnetic plunger79slidably arranged inside a solenoid80. The solenoid80can be controlled by signals received via the cable61P from the control system25. In this example, the plunger is received in a recess arranged in the filament module61. It is noted that the locking can be done the other way around wherein a recess in arranged in the top of the print head31. Other locking mechanisms are conceivable such as electromagnetic couplings that do not have any moving parts. It is noted that the locking mechanism78can support the filament at its locking function, meaning the locking mechanism78locks the filament module61to the print head31only in those situations wherein the filament also locks the mentioned modules. Alternatively, the locking mechanism78can perform the locking function by its own.

FIG.10shows a schematic side view of a part of the FFF system with the print head31mounted in the print head mount4. The print head31is attached to one of the filament modules61and moved towards one of the filament docks71. In this embodiment, the fused filament fabrication system1comprises a number of lifting modules101, each being arranged to lift one of the filament module docks, such as filament dock71or the print head dock8shown inFIGS.1and2. In this example, the lifting modules101are arranged at a top corner of the housing3. The lifting modules101are also referred to as lifting arrangements101. It is noted that the power cable leading to the filament module61is not shown in this figure. It should be noted that the housing3comprises on opening at the top in order to give way for the actions of the lifting module101. The housing3may have an even larger enclosure that is dimensioned so as to enclose the Bowden tubes and also the lifting modules101.

FIG.11shows the system in the situation wherein the print head31is lifted by means of the lifting module101and brought to a location out of the build chamber102. By removing the print head31from the build chamber102, more space is available to move the gantry for printing objects. As can be seen fromFIG.11, the print head mount4comprises a kinematic mount arranged to couple the print head31in a way appreciated by the skilled person. Other types of couplings are conceivable and known from the art.

The FFF system1may comprise a print head exchange dock105as shown inFIG.12which is arranged to connect to the selected print head31, remove the selected print head from the print head mount4, and to present the selected print head31to a user for removal of the selected print head31from the system1.FIG.12shows a top view of the FFF system1having three filament docks71,72,72arranged at a back side of the system1, whereas the print head exchange dock105is arranged at an opposing side. In this embodiment, the system1comprises a housing3enclosing the build space102and the printhead exchange dock105. The housing3comprises an opening106for external access to the printhead exchange dock105. In this way a user can load and unload a print head from the print head exchange dock105. In an embodiment, the print head exchange dock105can have a second function wherein it also functions as a print head dock for parking a print head without an intermediate filament module. In that case there is no need for the print head dock8shown inFIGS.1and2, which will leave room for arranging an additional filament dock if requested.

The printhead exchange dock105may be lifted by means of a lifting module107and placed into the print head mount4, seeFIG.13which shows a schematic side view of part of the FFF system1according to an embodiment.

FIG.14schematically shows a side view of an assembly of a print head31attached to the print head exchange dock105. The print head exchange dock105is arranged to slidably receive the print head31from a direction indicated by arrow141. For this purpose, the print head31may have a cross section as shown inFIGS.4B,5A and5B. It is noted that in the print head31inFIG.14does not contain a stopper such as the ridge82shown inFIG.4B.

A pivotable blocking lever142is arranged to block the movement of the print head31in order to avoid the user from pushing the print head too far into the FFF system. The pivotable blocking lever142may be pivotable around a pivot point143which may be coupled to the print head exchange dock105or an interfacing structure (not shown). In this embodiment, the print head31comprises a biased locking pin144which locks into a recess arranged in the print head exchange dock105. The locking pin144is arranged and biased in such a manner that the user can easily remove the print head31from the print head exchange dock105. To enable ergonomic unlocking, the pin144may have a rounded top, but other forms are possible as long as it enables unlocking of the print head31.

Once the print head31is docked into the print head exchange dock105for use in the FFF system, the print head31can be picked up by the print head mount4, seeFIG.15in which an arrow146indicates the movement of the print head31into the build volume102. Before the print head31can be moved through the build volume102by the gantry, the blocking lever142is pivoted so as to free the print head31. Pivoting of the blocking lever142can be performed using an activation mechanism such as an electrical driver (not shown), or it may be activated in a mechanical way during the lowering of the print head31in the build chamber by the lifting mechanism107shown inFIG.13.

FIG.16shows a top view of the FFF system1according to a further embodiment. In this embodiment the print head mount4is manoeuvred by means of a rail system with two static rails161,162and one moving rail163. The rail system or gantry is arranged to move the print head31in an X-direction and a Y-direction relative to a build plate2.

FIG.17shows a flow chart of a method170of fused filament fabrication according to an embodiment of the invention. The method comprises a step171of providing a fused filament fabrication system according to any one of the preceding claims, a step172of placing the print heads and the filament modules in the corresponding filament docks, a step173of feeding one or more filaments to the filament modules by means of the filament feeders, a step174of moving the gantry so that the print head mount is able to mount with a selected print head, and a step175of testing if the filament module that is attached to the selected print head is fed with a wanted filament. If this is the case, then the following steps are performed; locking176the selected print head to the attached filament module, and taking177the selected print head with the attached filament module from the filament dock, so as to be able to start a print task.

If it is decided from the testing step175that the filament module that is attached to the selected print head is not fed with a wanted filament, then the following steps are performed:unlocking178the selected print head from the attached filament module;placing179the selected print head into the print head dock;taking180the print head that is currently attached to the filament module having the wanted filament, and placing that print head into a filament dock without a docked print head;placing181the selected print head into the filament dock with the filament module having the wanted filament;locking182the selected print head to the filament module having the wanted filament,taking183the selected print head with the attached filament module from the filament dock, so as to be able to start a print task.

The present invention has been described above with reference to a number of exemplary embodiments as shown in the drawings. Modifications and alternative implementations of some parts or elements are possible, and are included in the scope of protection as defined in the appended claims. It should be noted that the above-mentioned embodiments illustrate rather than limit the invention, and that those skilled in the art will be able to design many alternative embodiments. In the claims, any reference signs placed between parentheses shall not be construed as limiting the claim. Use of the verb “comprise” and its conjugations does not exclude the presence of elements or steps other than those stated in a claim. The article “a” or “an” preceding an element does not exclude the presence of a plurality of such elements. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage.